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Question on Lorentz transforms and relativity of simultaneity

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  • #62
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    You continue to blatantly ignore everything I have said. Here is the important point again: In S', the experience processed by the brain is still of being blinded in both eyes simultaneously. This is because in S', brain activity itself exhibits RoS. So even though the Albert isn't struck simultaneously in S', his brain will still register simultaneous strikes for the same reason two clocks would register simultaneous strikes. You are consistently ignoring this point.

    So in your new, completely superfluous and irrelevant augmented thought experiment, both reference frames would agree that Albert blows up the bridge.
    I'm not ignoring it, it just doesn't address the issue.

    Do you disagree with the following:
    if two photons physically hit his retinae simultaneously, while he is standing on the embankment, then his brain will produce a simultaneous experience; if two photons hit his retinae non-simultaneously, while he is standing on the embankment, then his brain will produce a non-simultaneous experience?


  • #63
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    I'm not ignoring it, it just doesn't address the issue.

    Do you disagree with the following:
    if two photons physically hit his retinae simultaneously, while he is standing on the embankment, then his brain will produce a simultaneous experience; if two photons hit his retinae non-simultaneously, while he is standing on the embankment, then his brain will produce a non-simultaneous experience?

    Yes I disagree. The above is true in S but not in S'.


  • #64
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    Yes I disagree. The above is true in S but not in S'.
    We're not talking about either S or S' and we haven't specified which photons we're talking about; we're talking about how Albert's brain processes sensory information, that leads to Albert's experiences.

    Maybe if we personalise it a bit;
    do you agree, that if two photons physically hit your retinae simultaneously, while you are standing on an embankment, at rest relative to it, that your brain will produce a simultaneous experience?

    Do you agree that if two photons physically hit your retinae non-simultaneously, while you are standing on an embankment, at rest relative to it, that your brain will produce a non-simultaneous experience?

    Is this true or false for all physical photons?


  • #65
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    We're not talking about either S or S' and we haven't specified which photons we're talking about; we're talking about how Albert's brain processes sensory information, that leads to Albert's experiences.

    Yes we are talking about S and S'. What is and isn't "simultaneous" depends on what reference frame you are using.
    Maybe if we personalise it a bit;
    do you agree, that if two photons physically hit your retinae simultaneously, while you are standing on an embankment, at rest relative to it, that your brain will produce a simultaneous experience?

    Do you agree that if two photons physically hit your retinae non-simultaneously, while you are standing on an embankment, at rest relative to it, that your brain will produce a non-simultaneous experience?

    Is this true or false for all physical photons?

    Which reference frame are you referring to? If the strikes are simultaneous, as defined by S, then my brain will produce a "simultaneous" experience. The same is not true for simultaneous strikes as defined by S', however.


  • #66
    ceejay
    Registered Users, Registered Users 2 Posts: 456 ✭✭ceejay


    Consider this - for the brain to determine whether or not the retinas were stimulated by the photons at the same time or not, a signal must pass from each retina to some location in the brain which performs whatever operation is needed to compare two signals. So whether you're talking about retinas being stimulated and being assessed by an organic brain or some other light detecting devices with maybe some electronics comparing the signals, my point is that the comparison and the experience of simultaneity happens at a single location, and not two physically distinct locations. So the maths earlier show that the perception of the event will be that it is simultaneous no matter what reference frame you're using.

    Think of it more abstractly in terms of information, and how you could come to a decision about two pieces of information - you need to have the two pieces of info to hand to make a determination. The maths effectively show that if you observe the events simultaneously in your rest frame, other moving observers will also conclude that you observe them simultaneously, though not at the same moment in time. The light hitting the retinas is not enough for an observation, there has to be additional time for information to be passed somewhere to check for simultaneity.

    Also consider Occam's Razor applied to the situation: If your reasoning was sound then you could pick an infinite set of reference frames which would create whatever variation in time between events which in one particular frame of reference you would agree that they are simultaneous, and so in real life we would have many (possibly infinite) conflicting experiences of when things happen and in what order. Clearly that is not the case (at least not for me!), so therefore your reasoning is not sound, and humans do not experience multiple conflicting versions of events.

    You don't seem to want to accept what the maths says, that if two photons arrive at a point in space at the same time as expressed in one frame of reference, then all other reference frames will show that the two photons will still meet at that point in space at some instant, it's just when that instant is that won't be the same in the different frames of reference.


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  • #67
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    ceejay wrote: »
    Consider this - for the brain to determine whether or not the retinas were stimulated by the photons at the same time or not, a signal must pass from each retina to some location in the brain which performs whatever operation is needed to compare two signals. So whether you're talking about retinas being stimulated and being assessed by an organic brain or some other light detecting devices with maybe some electronics comparing the signals, my point is that the comparison and the experience of simultaneity happens at a single location, and not two physically distinct locations. So the maths earlier show that the perception of the event will be that it is simultaneous no matter what reference frame you're using.

    Think of it more abstractly in terms of information, and how you could come to a decision about two pieces of information - you need to have the two pieces of info to hand to make a determination. The maths effectively show that if you observe the events simultaneously in your rest frame, other moving observers will also conclude that you observe them simultaneously, though not at the same moment in time. The light hitting the retinas is not enough for an observation, there has to be additional time for information to be passed somewhere to check for simultaneity.

    Also consider Occam's Razor applied to the situation: If your reasoning was sound then you could pick an infinite set of reference frames which would create whatever variation in time between events which in one particular frame of reference you would agree that they are simultaneous, and so in real life we would have many (possibly infinite) conflicting experiences of when things happen and in what order. Clearly that is not the case (at least not for me!), so therefore your reasoning is not sound, and humans do not experience multiple conflicting versions of events.

    You don't seem to want to accept what the maths says, that if two photons arrive at a point in space at the same time as expressed in one frame of reference, then all other reference frames will show that the two photons will still meet at that point in space at some instant, it's just when that instant is that won't be the same in the different frames of reference.
    What we're interested in here, is not necessarily what other observers will conclude, we're interested in how Albert's brain processes his experiences.

    Let's ignore the issue of relativity of simultaneity for a second, and focus on how Albert's brain processes physical stimuli, when those stimuli reach him in his position on the platform.

    Let's say a photon hits his right retina first, and then five minutes later, a photon hits his left eye; will his brain process the information and produce a simultaneous experience? No, it won't, it will produce a non-simultaneous experience. This is because Albert's brain processes physical stimuli in the order they are received. This must be true for all photons which physically strike his retinae, or else we can conclude that there is a difference in the physicality of the photons.


    Now, back to RoS. S' says that the photons physically hit Albert's retinae non-simultaneously; now, as above, Albert's brain should process a non-simultaneous experience, if those photons are real, and physical.

    If we say that they only strike hit retinae non-simultaneously from the perspective of a relatively moving observer, then we are denying the physicality of the events as they strike Albert's retinae; because, as we have seen above, Albert's brain processes stimuli in the order they are received to produce his experiences, not the experience of a relatively moving observer.


    The point about Occam's Razor is simply evidence that the photons don't strike his retinae both simultaneously and non-simultaneously; because, if they did, they would produce two discordant experiences.


    It might be helpful to imagine yourself on the embankment, and imagine two photons striking your retinae simultaneously; ask yourself, how would your brain process the experience for you?

    Now imagine that two photons strike your retinae non-simultaneously; ask, how would your brain process the experience for you - not for some relatively moving observer?


  • #68
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    roosh wrote: »
    Let's say a photon hits his right retina first, and then five minutes later, a photon hits his left eye; will his brain process the information and produce a simultaneous experience?


    No, this is what happens. Your brain creates the illusion of simultaneity. Because your brain response are so slow relative to different nerve responses in your body. Your brain knows that you need the illusion of simultaneity, so your world doesn't fell wobbly - so that's the illusion it gives you.

    If I hit your knee, with a hammer, and you could see me do it. You would feel pain simultaneously to the hammer strike - this is your brain creating an illusion. If I did the hammer strikes without you seeing, you'd feel the pain 100, to even 200 milliseconds later - which sounds short but is really noticeable. Your brain cooks things up, so they look simultaneous even when they are not.

    Simultaneity, even within a frame, is a illusion.


  • #69
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    krd wrote: »
    No, this is what happens. Your brain creates the illusion of simultaneity. Because your brain response are so slow relative to different nerve responses in your body. Your brain knows that you need the illusion of simultaneity, so your world doesn't fell wobbly - so that's the illusion it gives you.

    If I hit your knee, with a hammer, and you could see me do it. You would feel pain simultaneously to the hammer strike - this is your brain creating an illusion. If I did the hammer strikes without you seeing, you'd feel the pain 100, to even 200 milliseconds later - which sounds short but is really noticeable. Your brain cooks things up, so they look simultaneous even when they are not.

    Simultaneity, even within a frame, is a illusion.
    If we ignore the thought experiment for a moment and just talk about how the brian processes information; if we take two random photons which physically hit our retinae non-simultaneously; that is, the left retina first and then the right retina. Our brain will process this sensory information in the order they are received. We know this, because not every single sensory experience is processed as a simultaneous events.

    So, we know that the brain will process sensory information in the order it is received, in general; we can, of course, use idealised observers and instruments in our thought experiments, so that we can avoid conclusions such as, relativity is true because our senses deceive us. But we know anyway, that all experiences aren't processed as simultaneous, so we know that there is an ordering anyway - I don't think the reflex analogy is the same as light being received through the retinae, anway, because the light has to travel the same distance to be processed in both cases.


    Knowing that our brain will process photons, which are physically received through the retinae, in the order they are received, we can ask, is this true for all photons, or just for some?


  • #70
    citrus burst
    Registered Users, Registered Users 2 Posts: 147 ✭✭citrus burst


    roosh wrote: »
    What we're interested in here, is not necessarily what other observers will conclude, we're interested in how Albert's brain processes his experiences.
    If this is the case, then the following is redundant.
    roosh wrote: »
    Let's ignore the issue of relativity of simultaneity for a second, and focus on how Albert's brain processes physical stimuli, when those stimuli reach him in his position on the platform.
    Usually in the order it is received.
    roosh wrote: »
    Let's say a photon hits his right retina first, and then five minutes later, a photon hits his left eye; will his brain process the information and produce a simultaneous experience? No, it won't, it will produce a non-simultaneous experience. This is because Albert's brain processes physical stimuli in the order they are received. This must be true for all photons which physically strike his retinae, or else we can conclude that there is a difference in the physicality of the photons.
    No because there is a time difference between the two photons. So why would he think they happened at the same time?
    roosh wrote: »
    Now, back to RoS. S' says that the photons physically hit Albert's retinae non-simultaneously; now, as above, Albert's brain should process a non-simultaneous experience, if those photons are real, and physical.
    See now you have thrown in an extra reference frame. At the start you just wanted to know what Albert observed. Albert makes his observation in S and as such has memories accordingly. How would S' have any bearing on Albert's memory/observation etc?

    Drop something on a train, you see it fall in a straight line (you're on the train by the way). I'm on the platform. I see if fall in a parabolic fashion. How does my observation/memory in any way affect yours?

    Now expand this to light and high velocities and once again what S' observes should have no bearing on what S observes.
    roosh wrote: »
    If we say that they only strike hit retinae non-simultaneously from the perspective of a relatively moving observer, then we are denying the physicality of the events as they strike Albert's retinae; because, as we have seen above, Albert's brain processes stimuli in the order they are received to produce his experiences, not the experience of a relatively moving observer.
    No we are not. Like you said "Albert's brain processes stimuli in the order they are received to produce his experiences." They are observed, in this case, where Albert makes his measurement, simultaneous in S. Therefore Albert's brain is stimulated in such a way that his memory recalls being hit by both photon at the same time.

    Again as you said "not the experience of a relatively moving observer." So why would his memories be in any way affected by S'. This line here pulls down your whole argument and logic.
    roosh wrote: »
    The point about Occam's Razor is simply evidence that the photons don't strike his retinae both simultaneously and non-simultaneously; because, if they did, they would produce two discordant experiences.
    They do in fact produce an infinite amount of experiences, not just two, but we are only using two reference frames. Why would the observations of one reference frame affect the observations of another and hence memory? Or as you put it:
    roosh wrote: »
    Albert's brain processes stimuli in the order they are received to produce his experiences, not the experience of a relatively moving observer.

    So either you do not understand the concept fully or you are arguing for the sake of arguing. You've managed to pick apart your own argument, yet still refuse to accept what you've been told countless times in this thread alone.
    roosh wrote: »
    It might be helpful to imagine yourself on the embankment, and imagine two photons striking your retinae simultaneously; ask yourself, how would your brain process the experience for you?

    You've already answered this yourself. The point of relativity of simultaneity is that in general, something that is simultaneous in one reference frame will not be simultaneous in another.

    This has absolutely no bearing on the physicality of observed events. Just the order in which they happen, as observed by a reference frame.
    roosh wrote: »
    Now imagine that two photons strike your retinae non-simultaneously; ask, how would your brain process the experience for you - not for some relatively moving observer?
    Again you've answered this yourself.


  • #71
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    Now, back to RoS. S' says that the photons physically hit Albert's retinae non-simultaneously; now, as above, Albert's brain should process a non-simultaneous experience, if those photons are real, and physical.

    I have already addressed this. S' says the photons hit Albert's retinae non-simultaneously. But since the brain is an extended object, S' also says simultaneity in brain activity is not the same as in S. Hence, S' says the photons hit non-simultaneously, and S' says Albert experiences this as being simultaneously blinded in both eyes.

    So both S and S' agree with what physically happens.


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  • #72
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Morbert wrote: »
    I have already addressed this.


    You just like going around in circles.


  • #73
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    This post is quite long, so it might be possible to take a different line, which starts with a very, very simple premise; a premise I presume you'll have no choice but to agree with; namely:

    Albert is an observer in Albert's reference frame.

    We can take that an progress from there if needs, be, but I've addressed the points raised below.

    citrus burst wrote: »
    If this is the case, then the following is redundant.
    Not necessarily, because are are interested in the physicality of the events as described by other reference frames.
    citrus burst wrote: »
    Usually in the order it is received.
    OK, so when photons make physical contact with Albert's retinae, his brain will process them in the order they are received.
    citrus burst wrote: »
    No because there is a time difference between the two photons. So why would he think they happened at the same time?
    We're just establishing a few things first about how Albert's brain processes photons which physically make contact with his retinae.

    Also, we don't need to worry about the "time" difference between the photons, we only need to consider that non-simultaneous means that one physically makes contact with the retinae before the other, such that we could label them in the order they are received i.e. 1 and 2.
    citrus burst wrote: »
    See now you have thrown in an extra reference frame. At the start you just wanted to know what Albert observed. Albert makes his observation in S and as such has memories accordingly. How would S' have any bearing on Albert's memory/observation etc?
    In the beginning we just wanted to establish how Albert's brian processes photons which make phyiscal contact with his retinae; as you said above, usually in the order they are received.

    We introduce the second reference frame because we are interested in the physicality of the events in that reference frame; bearing in mind how Albert's brain processes photons which make physical contact with his retinae.
    citrus burst wrote: »
    Drop something on a train, you see it fall in a straight line (you're on the train by the way). I'm on the platform. I see if fall in a parabolic fashion. How does my observation/memory in any way affect yours?
    This is a somewhat different example, because it doesn't involve photons making physical contact with our retinae - we can felsh it out so that it does, but then we have the same issue as we have been discussing.

    citrus burst wrote: »
    Now expand this to light and high velocities and once again what S' observes should have no bearing on what S observes.
    No, but the physicality of the events does have a bearing on what the "stationary" observer, or Albert observes; given what we know about how Albert's brain will process photons which physically make contact with his retinae.
    citrus burst wrote: »
    No we are not. Like you said "Albert's brain processes stimuli in the order they are received to produce his experiences." They are observed, in this case, where Albert makes his measurement, simultaneous in S. Therefore Albert's brain is stimulated in such a way that his memory recalls being hit by both photon at the same time.
    We can put away the metre sticks and clocks, because we're not interested in what Albert measures with his measuring instruments, we are interested in how his brain processes his experiences. As we have established, Albert's brain will process photons which physically make contact with his retinae, in the order they are received.

    According to S', the photons physically make contact with Albert's retinae non-simultaneously; that is, one physically makes contact with the right retina, for arguments sake, before the other physically makes contact with the left retina.

    Given what we know about how Albert's brain processes photons which physically make contact with his retinae - in the order they are received - if the photons physically make contact with his retinae in such a way that one physically makes contact before the other, Albert's brain should process them in that order and produce a non-simultaneous experience.

    Remembering that as far as Albert's brain is concerned, when it is processing Albert's experiences, the distance and time it takes for all photons which physically make contact with his retinae, or the signals which originate in the retinae, to reach any idealised "processing centre", is the same for both retinae; such that, if a pair of photons make physical contact with Albert's retinae, such that one arrives first and the other second, then his brain will process them to produce a non-simultaneous experience.

    citrus burst wrote: »
    Again as you said "not the experience of a relatively moving observer." So why would his memories be in any way affected by S'. This line here pulls down your whole argument and logic.
    Or so it would seem; but it's the physicality of the events as described by S' which we are interested in; S' says that the photons make physical contact with Albert's retinae non-simultaneously, in the physical world, where Albert is standing on the embankment.

    We know how Albert's brain processes all photons, which make physical contact with his retinae, to produce his experiences - as opposed to how a relativley moving observer will - supposedly - measure Albert's brian activity and the conclusion that relatively moving observer will - supposedly - arrive at, with regard to Albert's experiences.


    citrus burst wrote: »
    They do in fact produce an infinite amount of experiences, not just two, but we are only using two reference frames. Why would the observations of one reference frame affect the observations of another and hence memory? Or as you put it:
    Not for the same observer, as we can reason they should, given how we know how an observers brain processes physical stimuli which make physical contact with their retinae, for example.

    The observations of one reference frame would affect the experiences of another if the observations of that other "reference frame" pertain to photons which make physical contact with the other observers retinae.
    citrus burst wrote: »
    So either you do not understand the concept fully or you are arguing for the sake of arguing. You've managed to pick apart your own argument, yet still refuse to accept what you've been told countless times in this thread alone.
    I understand the concept, I'm just highlighting an example of how it cannot correspond to the physical world.

    citrus burst wrote: »
    You've already answered this yourself. The point of relativity of simultaneity is that in general, something that is simultaneous in one reference frame will not be simultaneous in another.
    and that all events as represented by the various reference frames correspond to real, physical events; such that, one reference frame says that photons make physical contact with an observers retinae simultaneously the other says that they make physical contact non-simultaneously.

    We know how an observers brain processes photons which make physical contact with the observers retinae, in the physical world, and that is how we arrive at our conclusion.

    The only question is, do the events in S' correspond to real physical events; that is, do the photons physically make contact with Albert's retinae in the order of one first, then the other? Because if they do, then this is the order in which Albert's brain will process them, to produce Albert's experiences; because that is how Albert's brain processes ALL photons which make phyiscal contact with his retinae.
    citrus burst wrote: »
    This has absolutely no bearing on the physicality of observed events. Just the order in which they happen, as observed by a reference frame.
    No, but the physicality of events, and the order they are received, does have a bearing on how an observer's brian will process them; in fact, it dictates how the brain will process them.
    citrus burst wrote: »
    Again you've answered this yourself.
    And hopefully any other perceived issues.


  • #74
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    I have already addressed this. S' says the photons hit Albert's retinae non-simultaneously. But since the brain is an extended object, S' also says simultaneity in brain activity is not the same as in S. Hence, S' says the photons hit non-simultaneously, and S' says Albert experiences this as being simultaneously blinded in both eyes.

    So both S and S' agree with what physically happens.
    And I have addressed this already, but I've no problem trying to clarify it until it is understood.

    We know how Albert's brian processes Albert's experiences; if photons make physical contact with his retinae, then his brian will process them in the order they arrive. For Albert's brain, when it is producing Albert's experiences, the distance and time it takes for physical stimuli to reach an idealised "processing centre" is the same for both retinae. This is how Albert's experiences are produced, by Albert's brain, while he is physically standing on the embankment.

    The only question which remains pertains to the physicality of the photons which make physical contact with his retinae, in the physical world, while he is physically standing on the emabnkment.

    S' says the photons physically make contact with Albert's retinae in a particular order, one first, then the other; given what we know about how Albert's brain operates, to produce Albert's experiences, if the photons make physical contact with Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment, then his brain will produce a non-simultaneous experience; from it's cosy position "in Albert's reference frame".

    The only question to be answered is, do the photons make physical contact with Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment?


  • #75
    ceejay
    Registered Users, Registered Users 2 Posts: 456 ✭✭ceejay


    roosh wrote: »
    S' says the photons physically make contact with Albert's retinae in a particular order, one first, then the other;

    Yes, we all agree with that
    roosh wrote: »
    given what we know about how Albert's brain operates, to produce Albert's experiences, if the photons make physical contact with Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment, then his brain will produce a non-simultaneous experience; from it's cosy position "in Albert's reference frame".

    Yes, in S that is true. However, in your argument you are ignoring the effects of relativity in the processing that the brain has to do when viewed from the perspective of S'. Your statements are saying that everything up to the retina will change in S' compared to S, but once the electrical impulses start flowing from the retinas into the brain and are being processed that this will be the same in S' and S - that is not correct. You have to consistently apply the Lorenz transformation to everything, you can't pick and chose what's affected and what's not.
    Morbert wrote: »
    But since the brain is an extended object, S' also says simultaneity in brain activity is not the same as in S. Hence, S' says the photons hit non-simultaneously, and S' says Albert experiences this as being simultaneously blinded in both eyes.

    So both S and S' agree with what physically happens.

    You can't treat the brain as a point object and everything that happens after the light hitting the retinas as a being instantaneous. The optic nerve is maybe 5cm in length, so even at the speed of light the fluctuations in the electric fields in the nerve will take 165 picoseconds to propagate, and then there's whatever other brain activity which may be located in physically separate parts of the brain requiring additional time for signals to pass, etc., plus then processing to compare the signals from each eye. All of this will experience relativistic effects, with the net effect that even though in S' the photons hit the retinas non-simultaneously, the experience for Albert in S' will be that they are simultaneous.

    Effectively the scenario can be represented by the original mathematical representation such that at x=0 the light is experienced as simultaneous at t=1 in S, and simultaneous at t=y in S'. The retinas and brain processing are just adding some equal steps to each leg of the journey of the information about each photon getting to x=0.


  • #76
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    ceejay wrote: »
    Yes, we all agree with that
    The question which then arises from that is, does the description of the events, as given by S', accurately correspond to the physical world?

    In the physical world, Albert is physically located on the embankment; so, do the photons physically hit Albert's retinae non-simultaneously, while Albert is physically standing on the embankment; that is, while Albert is standing on the embankment, do the photons physically hit his retinae in the order of, for arguments sake, right first and then left?
    ceejay wrote: »
    Yes, in S that is true. However, in your argument you are ignoring the effects of relativity in the processing that the brain has to do when viewed from the perspective of S'. Your statements are saying that everything up to the retina will change in S' compared to S, but once the electrical impulses start flowing from the retinas into the brain and are being processed that this will be the same in S' and S - that is not correct. You have to consistently apply the Lorenz transformation to everything, you can't pick and chose what's affected and what's not.
    It might be worth highlighting that I'm not saying that everything up to the retina will change in S', I'm simply asking if the events as described by S' correspond to the physical world; that is, do the photons physically hit Albert's retinae in the order of one first, then the other? Because, if they do, we can deduce how Albert's brain should process Albert's experience, based on how it processes other photons which physically hit his retinae, while he is standing on the embankment.

    Bear in mind, Albert's brain doesn't process Albert's experiences form the perspective of a relatively moving observer; Albert's brain doesn't apply the Lorentz transformation to its own neuronal activity; as far as Albert's brian is concerned, the length of time it take for signals from the retinae to reach the "processing centre" is the same for all photons which physically strike Albert's retinae, while Albert is standing on the embankment.

    That is why we ask the question, do the events, as described by S' correspond to the physical world; do the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment?
    ceejay wrote: »
    You can't treat the brain as a point object and everything that happens after the light hitting the retinas as a being instantaneous. The optic nerve is maybe 5cm in length, so even at the speed of light the fluctuations in the electric fields in the nerve will take 165 picoseconds to propagate, and then there's whatever other brain activity which may be located in physically separate parts of the brain requiring additional time for signals to pass, etc., plus then processing to compare the signals from each eye. All of this will experience relativistic effects, with the net effect that even though in S' the photons hit the retinas non-simultaneously, the experience for Albert in S' will be that they are simultaneous.
    We don't treat the brain as a point object, or at least I don't; we idealised the "processing centre" for the sake of argument; we also don't treat everything that happens after the light hitting the retinae as being instantaneous, we treat it how Albert's brian processes Albert's experiences.

    If Albert is standing on the embankment and two photons physically strike his retinae, right first and then the left; Albert's brain will process them in that order; the time it takes the signal from each retina to reach the "processing centre" will be the same for both eyes, such that, if the photons strike in the order of one first, then the other, Albert's experience will reflect this.

    ceejay wrote: »
    Effectively the scenario can be represented by the original mathematical representation such that at x=0 the light is experienced as simultaneous at t=1 in S, and simultaneous at t=y in S'. The retinas and brain processing are just adding some equal steps to each leg of the journey of the information about each photon getting to x=0.
    The issue is that we're not concerned with how a relatively moving observer will measure Albert's brain functions, and the conclusions he will draw about Albert's experiences.

    We are interested in how Albert's brain processes sensory stimuli, to produce Albert's experiences; we know that when Albert's brain is producing Albert's experiences, it will process physical stimuli in the order they are received; that is, if two photons physically strike Albert's retinae, in the order of one first, then the other, then his brain will produce a non-simultaneous experience.

    Knowing this we are only interested in the physicality of the events as described by S', and how they correspond to the physical world. S' says that the photons physically arrive at Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment. If this is true, the Albert's brain will process the photons which physically strike his retinae, the same way it processes ALL photons which phyiscally strike his retinae, in the order they are received; because this is how Albert's brain produces Albert's experiences.


    Some things that might be worth remembering ar that Albert's brain doesn't produce his experiences from the perspective of a relatively moving observer, and physical events don't happen "in" reference frames, because reference frames are constituted of mathematical co-ordinates which don't exist a priori in nature; reference frames are used to describe events which happen in the physical world, events don't happen "in" reference frames.


  • #77
    ceejay
    Registered Users, Registered Users 2 Posts: 456 ✭✭ceejay


    roosh wrote: »
    I'm simply asking if the events as described by S' correspond to the physical world; that is, do the photons physically hit Albert's retinae in the order of one first, then the other?

    The point is that there is no one definitive description of the sequence of events in "the physical world". The description of the events using S as the reference frame says the photons hit the retinas simultaneously and Albert experiences that as simultaneous, the description of events using S' as the reference frame says that the photons don't hit the retinas simultaneously but that Albert does still experience them simultaneously. Using the Lorenz transformations we can show that these descriptions are actually consistent with each other taking into account the relative velocity of the reference frames. Neither description is "more real" than the other, or than any other arbitrary reference frame.

    The reference frames are more than arbitrary mathematical constructs. They are how reality and the sequence of events appear to an observer at rest with respect to that reference frame. If we start talking about a reference frame, we are implicitly talking about how events would be perceived by an observer in that reference frame - and that perception will be different for observers in other reference frames.

    In our thought experiment there are two events where the photons hit each retina. An observer in S would describe them as simultaneous, an observer in S' would not. That is all. There are not four events - two simultaneous in S, and a different two non-simultaneous in S'. They are the same two physical real events, just experienced by different observers in S and S' as happening at different times.

    As you say yourself:
    roosh wrote: »
    Bear in mind, Albert's brain doesn't process Albert's experiences form the perspective of a relatively moving observer;

    Albert is in S and he experiences them as simultaneous.

    Some other observer (Barry) is in S' and they would experience them as non-simultaneous.

    Barry can use the Lorenz transformations to determine how the events would be experienced by an observer in S such as Albert, and would conclude that Albert would experience them as simultaneous.

    Equally Albert can use the transformations to work out how the events would be experienced by an observer in S' such as Barry and would conclude that Barry would experience them as non-simultaneous.

    roosh wrote: »
    Albert's brain doesn't apply the Lorentz transformation to its own neuronal activity; as far as Albert's brian is concerned, the length of time it take for signals from the retinae to reach the "processing centre" is the same for all photons which physically strike Albert's retinae, while Albert is standing on the embankment.

    Absolutely, and this is all about how things are percieved in S. The Lorenz transformations would only need to be applied to the neuronal activity etc. when Barry in S' is trying to work out how Albert in S would perceive the experiences.
    roosh wrote: »
    That is why we ask the question, do the events, as described by S' correspond to the physical world;
    Yes they do.
    roosh wrote: »
    do the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment?
    The description of the timing of the photons hitting Albert's retinas depends on the relative motion of the observer doing the describing relative to Albert. An observer standing still beside Albert would agree with Albert that they hit simultaneously. An observer moving quickly relative to Albert would say they hit at different times. Albert still sees them as simultaneous.

    roosh wrote: »
    If Albert is standing on the embankment and two photons physically strike his retinae, right first and then the left; Albert's brain will process them in that order;
    Yes, if that timing of the events is as described in Albert's frame of reference.
    roosh wrote: »
    the time it takes the signal from each retina to reach the "processing centre" will be the same for both eyes, such that, if the photons strike in the order of one first, then the other, Albert's experience will reflect this.
    Yes, again as described in Albert's frame of reference.
    roosh wrote: »
    The issue is that we're not concerned with how a relatively moving observer will measure Albert's brain functions, and the conclusions he will draw about Albert's experiences.
    But that is exactly the point - the relatively moving observer describes the events happening differently to how Albert describes them, but can use the maths to find how Albert would describe them.
    roosh wrote: »
    We are interested in how Albert's brain processes sensory stimuli, to produce Albert's experiences; we know that when Albert's brain is producing Albert's experiences, it will process physical stimuli in the order they are received; that is, if two photons physically strike Albert's retinae, in the order of one first, then the other, then his brain will produce a non-simultaneous experience.
    Yes, if that's how the sequence of the events is described in Albert's frame of reference.
    roosh wrote: »
    Knowing this we are only interested in the physicality of the events as described by S', and how they correspond to the physical world. S' says that the photons physically arrive at Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment.
    Correct so far, and the events are still the same two physical events, just described in S' with different timings.
    roosh wrote: »
    If this is true, the Albert's brain will process the photons which physically strike his retinae, the same way it processes ALL photons which phyiscally strike his retinae, in the order they are received; because this is how Albert's brain produces Albert's experiences.
    But the point is that how you describe "the order that they are received" is totally dependent on the frame of reference that you are using, and since Albert's experiences are tied to his frame of reference, "the order that they are received" for Albert is simultaneous. It doesn't matter how the events would be described by any other relatively-moving observer, since that doesn't change the fact that for Albert the events happen simultaneously. You can't take the sequence of hitting one retina first and then the other retina as described in S' and use it directly as-is in S without applying the Lorenz transformations, and when you do, the events become simultaneous in S.

    roosh wrote: »
    Some things that might be worth remembering ar that Albert's brain doesn't produce his experiences from the perspective of a relatively moving observer,
    Exactly! :)
    roosh wrote: »
    and physical events don't happen "in" reference frames, because reference frames are constituted of mathematical co-ordinates which don't exist a priori in nature; reference frames are used to describe events which happen in the physical world, events don't happen "in" reference frames.
    That is true, they are all the same events, the reference frames just give us different perspectives on when they happen - but no one description is more right/valid than another.


  • #78
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Again, thanks for the comprehensive reply ceejay.

    I think it is necessary to clarify a couple of things which are central to the question. The first thing is, we are not interested in how a relatively moving observer will measure Albert's brain activity, and the conclusion he will draw about Albert's perception; we are interested in the physical process which leads to Albert's brain producing Albert's experiences or perception - we can extrapolate this to a more precise "machine' later, but for the time being we can stick with Albert.

    The second point directly pertains to the following paragraph:
    ceejay wrote: »
    The reference frames are more than arbitrary mathematical constructs. They are how reality and the sequence of events appear to an observer at rest with respect to that reference frame. If we start talking about a reference frame, we are implicitly talking about how events would be perceived by an observer in that reference frame - and that perception will be different for observers in other reference frames.

    When we speak about reference frames, we are referring to the set of co-ordinate labels which are used to describe the events which occur in the physical world. The co-ordinate labels do not exist a priori in nature, so the reference frames that we refer to are mathematical constructs; that is, they are "mathematical things", not physical. These reference frames are used to describe the events which occur in the physical world and to describe how physical observers measure those events.

    In that sense, we cannot really say that events occur "in" a reference frame, because that would be to ascribe physical properties to mathematical reference frames; more accurately we should say that the reference frames describe the physical events, or the events as described in, or by, the reference frames. This, I think, is part of the issue because it can cloud our reasoning if we aren't clear on it.

    In a separate discussion on the same issue, a "proponent of Einsteinian relativity" - making the very same point that you are making in the response below - stated that "Albert isn't really an observer in Albert's reference frame", in the sense of Albert the physical person; when we say Albert in Albert's reference frame, we mean the co-ordinates which represent Albert in a given reference frame - this is an important distinction which we will discuss below.
    ceejay wrote: »
    The point is that there is no one definitive description of the sequence of events in "the physical world". The description of the events using S as the reference frame says the photons hit the retinas simultaneously and Albert experiences that as simultaneous, the description of events using S' as the reference frame says that the photons don't hit the retinas simultaneously but that Albert does still experience them simultaneously. Using the Lorenz transformations we can show that these descriptions are actually consistent with each other taking into account the relative velocity of the reference frames. Neither description is "more real" than the other, or than any other arbitrary reference frame.
    Indeed, relativity says that the events described by any particular reference frame are not "more real" than those described by any other; the events described in every rerference frame are as real, and as physical, as those described in every other reference frame. This is what relativity says, but what we want to do is relate these descriptions of events back to the physical world.

    Albert's Brain
    Let's start with what we know about how Albert's brain processes Albert's experiences; let's say that Albert is standing on the embankment, it's pitch black and his assistant hasn't arrived with his instruments yet, but someone is testing the lasers that will be used in the experiment; so we're not talking about the simultaneous/non-simultaneous events just yet.

    Standing on the embankment, Albert sees two flashes of light, but they don't seem to flash together; Albert sees the one from the right first, and then the one from the left - this must be because the tester has fired them in this order, although that is not necessarily relevant for this line of reasoning.

    We know that Albert sees the one from the right first and then the one from the left; we are interested in why this is. Knowing how Albert's brain operates, when producing Albert's perceptions, we can deduce that the reason he sees the right flash first and then the left, is because the photons from the right laser must have physically hit his right retina first and the photon from the left laser must have physically hit his left retina second; such that the order of the physical contact between the photons and Albert's retinae must have been right first and left second. The time difference between them doesn't matter here, we are only interested in the order.

    This means that Albert's brain processes photons which physically strike his retinae, in the order in which they make physical contact wth the retina, or cornea, or, for simplicity sake, eye.

    This is how Albert's brain will process ALL photons which physically make contact with his eyes; namely, in the order they are received. From here, we are only interested in the order in which the photons make physical contact with Albert's eyes and the physicality of any descriptions which describe the order in which the photons hit Albert's eyes - because we know that Albert's brain will process ALL photons in the order they are received, to give Albert the consequentially ordered perception.
    ceejay wrote: »
    In our thought experiment there are two events where the photons hit each retina. An observer in S would describe them as simultaneous, an observer in S' would not. That is all. There are not four events - two simultaneous in S, and a different two non-simultaneous in S'. They are the same two physical real events, just experienced by different observers in S and S' as happening at different times.

    As you say yourself:


    Albert is in S and he experiences them as simultaneous.

    Some other observer (Barry) is in S' and they would experience them as non-simultaneous.

    Barry can use the Lorenz transformations to determine how the events would be experienced by an observer in S such as Albert, and would conclude that Albert would experience them as simultaneous.

    Equally Albert can use the transformations to work out how the events would be experienced by an observer in S' such as Barry and would conclude that Barry would experience them as non-simultaneous.
    Here we come across the issue that was alluded to above, the issue of saying that physical observers are "in" mathematical reference frames. If we say that "Albert is in S", then by extension Albert's retinae are in S, such that, any event which occurs on the surface of Albert's retinae must necessarily occur in S, or "in Albert's reference frame"; so, if S' says that the photons physically strike Albert's retinae non-simultaneously, they must necessarily strike them non-simultaneously "in Albert's reference frame" or in S.

    But we know that that is not what relativity says, so there must be an issue with our statement "Albert is in S"; the issue is addressed when we acknowledge that Albert isn't "in" S, and the photons don't strike his retinae "in" S, but that S is a mathematical representation of the events which occur in the physical world. Similarly, S' is a mathematical representation of the measurements of a relatively moving observer. This just brings us back to the question of how the relatively moving observer's measurements correspond to the physical world and the physical events. Do the photons physically strike Albert's retinae non-simultaneously? Because if they do, we know how Albert's brain will process them to create Albert's experience, in the physical world, on the embankment. Again, we are not interested in how a relatively moving observer will, supposedly, measure Albert's brain activity, and the conlcusion he will, supposedly, arrive at, with respect to Albert's experiences - we are interested in Albert's experiences, not the relatively moving observers; here the physicality of the non-simultaneous retinae striking events is key.


    ceejay wrote: »
    Absolutely, and this is all about how things are percieved in S. The Lorenz transformations would only need to be applied to the neuronal activity etc. when Barry in S' is trying to work out how Albert in S would perceive the experiences.
    How things are perceived by Albert "in" S depends on how his brain processes physical stimuli which make physical contact with his retinae; we know that his brain processes photons in the order in which they make physical contact with his retinae.

    We are not interested in how Barry, supposedly, measures Albert's brain activity and what his, supposed, perception of Albert's experience will be.

    ceejay wrote: »
    Yes they do [correspond to the physical world].
    If they correspond to the physical world, then it means that photons physically strike Albert's retinae in the order of one first then the other, while Albert is standing on the embankment. If this is true, then Albert's brain will process them in that order and produce a non-simultaneous perception.

    ceejay wrote: »
    The description of the timing of the photons hitting Albert's retinas depends on the relative motion of the observer doing the describing relative to Albert. An observer standing still beside Albert would agree with Albert that they hit simultaneously. An observer moving quickly relative to Albert would say they hit at different times. Albert still sees them as simultaneous.
    The question we are interested in is, is the description of events, as described by the relatively moving observer accurate, and do they correspond to the physical world; that is, the relatively moving observer says that, while Albert is standing on the embankment, photons make physical contact with his retinae in the order of one first, then the other; we want to know whether or not the photons do make physical contact with Albert's retinae, in the order of one first, then the other, while Albert is standing on the embankment; because if they do, then this is how Albert's brain will process them, and the perception or experience it produces will be a non-simultaneous one.

    ceejay wrote: »
    Yes, if that timing of the events is as described in Albert's frame of reference.

    Yes, if that's how the sequence of the events is described in Albert's frame of reference.
    Albert's brain operates in the physical world; it will process physical photons which physically strike his retinae in the order they are received, while he is standing on the embankment. If reference frames don't reflect this fact, then they do not describe the physical world.
    ceejay wrote: »
    Yes, again as described in Albert's frame of reference.
    Again, this is how Albert's brain will process Albert's experiences, while Albert is physically standing on the embankment; we are not interested in how Barry will, supposedly, measure Albert's brain activity, or what Barry's, supposed, perception of Albert's experience will be.
    ceejay wrote: »
    But that is exactly the point - the relatively moving observer describes the events happening differently to how Albert describes them, but can use the maths to find how Albert would describe them.
    We are just interested in the physicality of the events as described by the relatively moving observer; that is, do the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is standing on the embankment? If they do, we know how Albert's brain processes ALL photons which make physical contact with his retinae in the order of one first then the other.

    ceejay wrote: »
    Correct so far, and the events are still the same two physical events, just described in S' with different timings.
    Indeed, this is the idea; as described by S', the photons, supposedly, make physical contact with Albert's retinae in the order of one first then the other; if this is true, then this is how Albert's brain will process them to produce Albert's experience; because Albert's brain processes ALL photons, which make physical contact with his eyes, in the order they are received.
    ceejay wrote: »
    But the point is that how you describe "the order that they are received" is totally dependent on the frame of reference that you are using, and since Albert's experiences are tied to his frame of reference, "the order that they are received" for Albert is simultaneous. It doesn't matter how the events would be described by any other relatively-moving observer, since that doesn't change the fact that for Albert the events happen simultaneously. You can't take the sequence of hitting one retina first and then the other retina as described in S' and use it directly as-is in S without applying the Lorenz transformations, and when you do, the events become simultaneous in S.
    Albert's experiences aren't tied to any mathematical description of physical events; Albert's brian operates in the physical world and it will process ALL photons, which physically strike his eyes, in the order they are received.

    Again, we are interested in the physicality of the events described by the reference frames; we want to know if the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment. If they do, then Albert's brain will process them in that order.

    ceejay wrote: »
    That is true, they are all the same events, the reference frames just give us different perspectives on when they happen - but no one description is more right/valid than another.
    Indeed, no one is more valid than the other, all are, supposedly, equally physical. If the events as described by S' are physical, then it means that photons physically strike Albert's retinae in the order of one first then the other; if this is true, then Albert's retinae will process them in that order, and produce a non-simultaneous experience.


  • #79
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Apologies, I forgot to reply to this post.
    Morbert wrote: »
    Yes we are talking about S and S'. What is and isn't "simultaneous" depends on what reference frame you are using.
    We don't need to reference any reference frames initially, we can just establish how Albert's brain processes physical stimuli. We know that, while Albert is physically standing on the embankment, his brain will process all photons, which physically strike his retinae, in the order they are received; that is, if photons physically strike his retinae in the order of one first then the other, while he is standing on the embankment, his brian will process them in that order.

    From there we are only interested in the physicality of events as described by the different reference frames. S' says that, while Albert is physically standing on the embankment, two photons physically strike his retinae in the order of one first then the other; if this is true, then knowing how Albert's brain processes photons which physically strike his retinae, his brain should produce an experience of light flashing in the order of one side first, then the other.
    ceejay wrote: »
    Which reference frame are you referring to?
    If the strikes are simultaneous, as defined by S, then my brain will produce a "simultaneous" experience. The same is not true for simultaneous strikes as defined by S', however.
    I'm referring to the physical world; if photons physically strike your retinae in the order of one first then the other, while you are standing in your front garden, at rest relative to the garden, will your brain process them in that order?

    Bearing in mind that the order of events doesn't depend on how they are described by mathematical reference frames. The mathematical reference frames can help us deduce how one observer will, supposedly, measure the events, given the co-ordinates of the events in another reference frame.

    We are then interested in how these descriptions relate back to the physical world; that is, if, according to S', the photons strike Albert's retinae in the order of one first then the other, while he is standing on the embankment, do they physically strike his retinae in the order of one first then the other?

    If they do, then we know how Albert's brain processes photons which physically strike his retinae in the order of one first, then the other, while he is standing on the embankment.


  • #80
    citrus burst
    Registered Users, Registered Users 2 Posts: 147 ✭✭citrus burst


    I don't think any one here is debating whether the order in which information is received, is the order in which it is processed.
    roosh wrote: »
    Again, thanks for the comprehensive reply ceejay.

    I think it is necessary to clarify a couple of things which are central to the question. The first thing is, we are not interested in how a relatively moving observer will measure Albert's brain activity, and the conclusion he will draw about Albert's perception; we are interested in the physical process which leads to Albert's brain producing Albert's experiences or perception - we can extrapolate this to a more precise "machine' later, but for the time being we can stick with Albert.
    So you only want to know how one observer in one reference frame will determine physical observations? In this case; our lovely test subject Albert sitting on an embankment. Well we have clarified many times that he will determine processes to occur in the order he receives them, no?

    That is to say he doesn't perceive things "backwards" in a sense that, a plate is broken on the ground, recombines and the then flies back up to the top of a table, is considered "backwards" as that's not how the event actually happened. He actually received the information as the plate falling, breaking and lying in pieces.

    Next thing to add on is that, if he receives two pieces of information at the same time, he perceives these things to happen at the same time, no? But this does not mean that he is correct. Events can be spatially or temporally separated. For example he might receive the information of a star going supernova and a green light signal at the same time and consider that they both "physically" happened at the same time. But the star went supernova millions of years ago, it just took the light that long to get to him.

    roosh wrote: »


    When we speak about reference frames, we are referring to the set of co-ordinate labels which are used to describe the events which occur in the physical world. The co-ordinate labels do not exist a priori in nature, so the reference frames that we refer to are mathematical constructs; that is, they are "mathematical things", not physical. These reference frames are used to describe the events which occur in the physical world and to describe how physical observers measure those events.

    Well no I think we need to lend a bit more physical structure to reference frames in the that they are real. True, yes the labels we use are arbitrary and only mathematical concepts physicists use to make their problems easier and therefore don't exist in nature. But the actual reference frame itself, where "things can happen" do exist in nature. I mean trains, planes, boats, cars and spaceships are real in nature and are designed to "exist" in different reference frames then the earth in order to allow faster movement between the arbitrary points on the earth's surface that we use to describe location. The points aren't real, but the reference frames are there. Unless you are denying the fact that we exist etc but I don't think we need to debate existence at this point.
    roosh wrote: »
    In that sense, we cannot really say that events occur "in" a reference frame, because that would be to ascribe physical properties to mathematical reference frames; more accurately we should say that the reference frames describe the physical events, or the events as described in, or by, the reference frames. This, I think, is part of the issue because it can cloud our reasoning if we aren't clear on it.
    Well no they don't occur in the arbitrary points (x,y,z,t) that we use to "locate" the reference frame. But they do occur in physical parts where the experiment, whatever happened.

    No one is denying here that, the mathematical reference part is just an address given to something, so that it can be used to gain data from, pretty much.
    roosh wrote: »
    In a separate discussion on the same issue, a "proponent of Einsteinian relativity" - making the very same point that you are making in the response below - stated that "Albert isn't really an observer in Albert's reference frame", in the sense of Albert the physical person; when we say Albert in Albert's reference frame, we mean the co-ordinates which represent Albert in a given reference frame - this is an important distinction which we will discuss below.
    Sure, ok.
    roosh wrote: »
    Indeed, relativity says that the events described by any particular reference frame are not "more real" than those described by any other; the events described in every rerference frame are as real, and as physical, as those described in every other reference frame. This is what relativity says, but what we want to do is relate these descriptions of events back to the physical world.
    Well if there are real, they must be physical? They might contradict each other, but they are still physical. I mean how can a radio in the same reference frame be loud and quiet?
    roosh wrote: »
    Albert's Brain
    Let's start with what we know about how Albert's brain processes Albert's experiences; let's say that Albert is standing on the embankment, it's pitch black and his assistant hasn't arrived with his instruments yet, but someone is testing the lasers that will be used in the experiment; so we're not talking about the simultaneous/non-simultaneous events just yet.
    Ok, you can mess around with your thought experiment as much as you like, as long as you give us the same freedom.
    roosh wrote: »
    Standing on the embankment, Albert sees two flashes of light, but they don't seem to flash together; Albert sees the one from the right first, and then the one from the left - this must be because the tester has fired them in this order, although that is not necessarily relevant for this line of reasoning.
    So what can we deduce straight away from this? Not just necessarily that they were fired at different times.

    1) as you say the hatch on laser A was opened first and then the hatch on laser B was opened.
    2) the hatch on both lasers was opened at the same time. Laser A is just closer then laser B.
    3) the light from laser A is faster then the light from B.

    Now we can throw away 3 straight away as every modern day physics theory is based on the speed on light being constant.

    Again as you said, its dark so Albert doesn't know which of one or two is different. We can specify in the experiment which is the case.
    roosh wrote: »
    We know that Albert sees the one from the right first and then the one from the left; we are interested in why this is. Knowing how Albert's brain operates, when producing Albert's perceptions, we can deduce that the reason he sees the right flash first and then the left, is because the photons from the right laser must have physically hit his right retina first and the photon from the left laser must have physically hit his left retina second; such that the order of the physical contact between the photons and Albert's retinae must have been right first and left second. The time difference between them doesn't matter here, we are only interested in the order.
    Because, like I said earlier, either situation 1 or 2 is set up. And like we have all said earlier, Albert's brain perceives information in the order it is received. I don't know why you keep bringing this point up since no one is debating it?

    Why do we not care about the time of the events? Order depends on the timing of the events,no? Depending on the timing they could be simultaneous, or not.
    roosh wrote: »
    This means that Albert's brain processes photons which physically strike his retinae, in the order in which they make physical contact wth the retina, or cornea, or, for simplicity sake, eye.
    So can we now make this a postulate of your argument and assume it is now true in all cases?
    roosh wrote: »
    This is how Albert's brain will process ALL photons which physically make contact with his eyes; namely, in the order they are received. From here, we are only interested in the order in which the photons make physical contact with Albert's eyes and the physicality of any descriptions which describe the order in which the photons hit Albert's eyes - because we know that Albert's brain will process ALL photons in the order they are received, to give Albert the consequentially ordered perception.
    But order depends on (x,t), so it is not as simple as you say.
    roosh wrote: »
    Here we come across the issue that was alluded to above, the issue of saying that physical observers are "in" mathematical reference frames. If we say that "Albert is in S", then by extension Albert's retinae are in S, such that, any event which occurs on the surface of Albert's retinae must necessarily occur in S, or "in Albert's reference frame"; so, if S' says that the photons physically strike Albert's retinae non-simultaneously, they must necessarily strike them non-simultaneously "in Albert's reference frame" or in S.
    See, this is where you lose me. Up until you say "so, if S' says that the photons physically" is fairly self evident. But I have no idea what you mean after, where you get you argument and logic from.

    How do you draw the conclusion that what S' perceives is what S should perceive? You said it yourself "If we say that "Albert is in S", then by extension Albert's retinae are in S, such that, any event which occurs on the surface of Albert's retinae must necessarily occur in S, or "in Albert's reference frame"

    This basically means we are obliged to use the same coordinate system for all of S. We also have to use a different coordinate system for S'. This for me is a pretty big problem and one you should look to address and make self consistent. Or in the very least explain it in a better, easier to understand way, as simply as possible.
    roosh wrote: »
    But we know that that is not what relativity says, so there must be an issue with our statement "Albert is in S"; the issue is addressed when we acknowledge that Albert isn't "in" S, and the photons don't strike his retinae "in" S, but that S is a mathematical representation of the events which occur in the physical world. Similarly, S' is a mathematical representation of the measurements of a relatively moving observer. This just brings us back to the question of how the relatively moving observer's measurements correspond to the physical world and the physical events. Do the photons physically strike Albert's retinae non-simultaneously? Because if they do, we know how Albert's brain will process them to create Albert's experience, in the physical world, on the embankment. Again, we are not interested in how a relatively moving observer will, supposedly, measure Albert's brain activity, and the conlcusion he will, supposedly, arrive at, with respect to Albert's experiences - we are interested in Albert's experiences, not the relatively moving observers; here the physicality of the non-simultaneous retinae striking events is key.
    The only issue so far that we have encountered is your comments in the previous.

    The issue isn't addressed when we say Albert isn't "in" S. He might as well be. He's on an embankment on the earth. Earth can be moving at any arbitrary speed, but we might as well say its not moving, because we'll have to "add" its initial speed onto the relatively moving observer.

    We use the tags S and S' to show that they are in different frames. The photons physically hit his eyes on the earth. This is described by S. The photons then have to travel to S', in order to be observed by the relatively moving observer. Due to the motion of S' the light will be received differently then how it was received in S. But like you said we don't care about how S' observed the light.


    roosh wrote: »


    How things are perceived by Albert "in" S depends on how his brain processes physical stimuli which make physical contact with his retinae; we know that his brain processes photons in the order in which they make physical contact with his retinae.
    Your postulate again
    roosh wrote: »
    We are not interested in how Barry, supposedly, measures Albert's brain activity and what his, supposed, perception of Albert's experience will be.
    Ok, but, why are we sometimes interested?
    roosh wrote: »

    If they correspond to the physical world, then it means that photons physically strike Albert's retinae in the order of one first then the other, while Albert is standing on the embankment. If this is true, then Albert's brain will process them in that order and produce a non-simultaneous perception.
    Your postulate.
    roosh wrote: »
    The question we are interested in is, is the description of events, as described by the relatively moving observer accurate, and do they correspond to the physical world; that is, the relatively moving observer says that, while Albert is standing on the embankment, photons make physical contact with his retinae in the order of one first, then the other; we want to know whether or not the photons do make physical contact with Albert's retinae, in the order of one first, then the other, while Albert is standing on the embankment; because if they do, then this is how Albert's brain will process them, and the perception or experience it produces will be a non-simultaneous one.
    So now we are interested in S' again? It is accurate and does correspond to the physical world.
    roosh wrote: »
    Albert's brain operates in the physical world; it will process physical photons which physically strike his retinae in the order they are received, while he is standing on the embankment. If reference frames don't reflect this fact, then they do not describe the physical world.
    So does mine, and it also follows your postuale.
    roosh wrote: »
    Again, this is how Albert's brain will process Albert's experiences, while Albert is physically standing on the embankment; we are not interested in how Barry will, supposedly, measure Albert's brain activity, or what Barry's, supposed, perception of Albert's experience will be.
    So now we are not interested in S'?
    roosh wrote: »
    We are just interested in the physicality of the events as described by the relatively moving observer; that is, do the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is standing on the embankment? If they do, we know how Albert's brain processes ALL photons which make physical contact with his retinae in the order of one first then the other.
    Yup your postulate seems to be true.
    roosh wrote: »
    Indeed, this is the idea; as described by S', the photons, supposedly, make physical contact with Albert's retinae in the order of one first then the other; if this is true, then this is how Albert's brain will process them to produce Albert's experience; because Albert's brain processes ALL photons, which make physical contact with his eyes, in the order they are received.
    So now we are interested in S' again? You've got to remember that for S' the light hits Albert and then gets detected by S'. It has a longer path to take then in S. Albert gets hit in the reference frame, as described mathematically by S.
    roosh wrote: »
    Albert's experiences aren't tied to any mathematical description of physical events; Albert's brian operates in the physical world and it will process ALL photons, which physically strike his eyes, in the order they are received.
    No they are described by them. Language is no way tied to the letters that are used to describe it, yet you don't seem to be debating it.
    roosh wrote: »
    Again, we are interested in the physicality of the events described by the reference frames; we want to know if the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is physically standing on the embankment. If they do, then Albert's brain will process them in that order.
    So you want to test your postulate?
    roosh wrote: »
    Indeed, no one is more valid than the other, all are, supposedly, equally physical. If the events as described by S' are physical, then it means that photons physically strike Albert's retinae in the order of one first then the other; if this is true, then Albert's retinae will process them in that order, and produce a non-simultaneous experience.

    So what you are saying does the moon, which is moving relative to the earth affect, my measurement, on earth? Since the moon measures an event that was simultaneous on earth not simultaneous due to its relative motion?

    I would take exception to the line "If the events as described by S' are physical, then it means that photons physically strike Albert's retinae in the order of one first then the other; if this is true, then Albert's retinae will process them in that order, and produce a non-simultaneous experience."

    How did you deduce this? Well not deduce, how did you put these two together and get 4? Please try and explain this to me


  • #81
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    citrus burst wrote: »
    I don't think any one here is debating whether the order in which information is received, is the order in which it is processed.
    That's great. The important point then is photons physically making contact with the retinae of an observer constitutes "receiving information".

    citrus burst wrote: »
    So you only want to know how one observer in one reference frame will determine physical observations? In this case; our lovely test subject Albert sitting on an embankment. Well we have clarified many times that he will determine processes to occur in the order he receives them, no?

    That is to say he doesn't perceive things "backwards" in a sense that, a plate is broken on the ground, recombines and the then flies back up to the top of a table, is considered "backwards" as that's not how the event actually happened. He actually received the information as the plate falling, breaking and lying in pieces.

    Next thing to add on is that, if he receives two pieces of information at the same time, he perceives these things to happen at the same time, no? But this does not mean that he is correct. Events can be spatially or temporally separated. For example he might receive the information of a star going supernova and a green light signal at the same time and consider that they both "physically" happened at the same time. But the star went supernova millions of years ago, it just took the light that long to get to him.
    On the basis of seeing both lights at the same time, and no other information, if Albert concludes anything more than that he saw the lights at the same time, then he is potentially setting himself up to be incorrect. What he can conclude is that photons from both events struck his retinae at the same time, and this is why his brain processed the flahses as occurring together.

    The breaking plate example is somewhat different to the question we are considering, but it isn't one that is disputed.

    citrus burst wrote: »
    Well no I think we need to lend a bit more physical structure to reference frames in the that they are real. True, yes the labels we use are arbitrary and only mathematical concepts physicists use to make their problems easier and therefore don't exist in nature. But the actual reference frame itself, where "things can happen" do exist in nature. I mean trains, planes, boats, cars and spaceships are real in nature and are designed to "exist" in different reference frames then the earth in order to allow faster movement between the arbitrary points on the earth's surface that we use to describe location. The points aren't real, but the reference frames are there. Unless you are denying the fact that we exist etc but I don't think we need to debate existence at this point.
    We don't need to lend more physical structure to the mathematical co-ordinates, I think that is part of the underlying issue. We can treat the mathematical co-ordinate systems as they are, a means of describing what occurs in those physical reference frames you mention, the car, the boat, the spaceship etc. It can cloud our reasoning if we don't make this distinction, because we start to make statements such as "it occurs in this reference frame but not in that"; this is made clearer when we talk about photons making physical contact with the retinae of an observer. If we say they make physical contact in a certain order in one reference frame, but not in the other, then we are suggesting that an observers retinae can be both in a reference frame and not in a reference frame.

    When we make explicit reference to the physical location of the observer we can avoid this conflation. When we say that one reference frame describes the physical events in such a way that it says the photons make physical contact with the observers retinae, in the order of one first then the other, while he is standing on the embankment, then we can make deductions based on what we know about how an observers brain will process photons which physically strike the observers retinae i.e. in the order that they physically hit the retinae.

    citrus burst wrote: »
    Well no they don't occur in the arbitrary points (x,y,z,t) that we use to "locate" the reference frame. But they do occur in physical parts where the experiment, whatever happened.

    No one is denying here that, the mathematical reference part is just an address given to something, so that it can be used to gain data from, pretty much.
    Indeed, S' says that, while Albert is physically standing on the embankment, photons physically strike his retinae in the order of one first, then the other. Given our postulate, we know how Albert's brain should process any photons, which make physical contact with his retinae, to produce his experience, while he is standing on the embankment

    citrus burst wrote: »
    Well if there are real, they must be physical? They might contradict each other, but they are still physical. I mean how can a radio in the same reference frame be loud and quiet?
    If the events as described by S' are real, physical, valid, or however we wish to describe them; if they correspond to the physical world, then it means that photons physically strike Albert's retinae in the order of one first, then the other, while he is physically standing on the embankment. If this is true, given our postulate, we know how Albert should process photons which physically strike his retinae, while he is standing on the emabnkment.

    citrus burst wrote: »
    Ok, you can mess around with your thought experiment as much as you like, as long as you give us the same freedom.
    We mess around with the thought experiment solely to establish the postulate to which you have agreed. But, of course, the same freedom must be extended.
    citrus burst wrote: »
    So what can we deduce straight away from this? Not just necessarily that they were fired at different times.

    1) as you say the hatch on laser A was opened first and then the hatch on laser B was opened.
    2) the hatch on both lasers was opened at the same time. Laser A is just closer then laser B.
    3) the light from laser A is faster then the light from B.

    Now we can throw away 3 straight away as every modern day physics theory is based on the speed on light being constant.

    Again as you said, its dark so Albert doesn't know which of one or two is different. We can specify in the experiment which is the case.
    What we can also deduce, and which is the important point for the issue in question, is that the photons from one laser physically struck his retinae in the order of A first, then then B.

    citrus burst wrote: »
    Because, like I said earlier, either situation 1 or 2 is set up. And like we have all said earlier, Albert's brain perceives information in the order it is received. I don't know why you keep bringing this point up since no one is debating it?

    Why do we not care about the time of the events? Order depends on the timing of the events,no? Depending on the timing they could be simultaneous, or not.
    We're not interested in the timing because there are a near infinite range of time values which can result in a given order of events, we are only interested in the order in which the photons make physical contact with Albert's retinae, because we know that is how his brain will process them.

    citrus burst wrote: »
    So can we now make this a postulate of your argument and assume it is now true in all cases?
    True for all photons which make physical contact with an observers retinae?

    citrus burst wrote: »
    But order depends on (x,t), so it is not as simple as you say.
    I would be more inclined to say that (x,t) depend on the order; that is, I would ascribe the causal influence to the physical events, not the mathematical co-ordinates.

    citrus burst wrote: »
    See, this is where you lose me. Up until you say "so, if S' says that the photons physically" is fairly self evident. But I have no idea what you mean after, where you get you argument and logic from.

    How do you draw the conclusion that what S' perceives is what S should perceive?
    The logic is quite simple. We have the agreed postulate which tells us how Albert's brain will process all photons which make physical contact with Albert's retinae, while Albert is physically standing on the embankment; that is, in the order they make phyiscal contact with his retinae.

    S' says that the photons make physical contact with Albert's retinae, in the order of one first, then the other, while Albert is physically standing on the embankment. If this is valid, then Albert's brain should process them in that order, given the agreed upon postulate.

    citrus burst wrote: »
    You said it yourself "If we say that "Albert is in S", then by extension Albert's retinae are in S, such that, any event which occurs on the surface of Albert's retinae must necessarily occur in S, or "in Albert's reference frame"

    This basically means we are obliged to use the same coordinate system for all of S. We also have to use a different coordinate system for S'. This for me is a pretty big problem and one you should look to address and make self consistent. Or in the very least explain it in a better, easier to understand way, as simply as possible.
    This is just highlighting the issue of making such statements as "the photons strike Albert's retinae simultaneously 'in Albert's reference frame'" or "the photons strike Albert's retinae non-simultaneously 'not in Albert's reference frame'".

    If Albert is in Albert's reference frame, then so are his retinae; if photons physically strike his retinae then they necessarily strike them "in Albert's reference frame". So if S' says they strike Albert's retinae non-simultaneously, then they must, necessarily, strike Albert's retinae non-simultnaeously "in Albert's reference frame" if Albert and his retinae are "in Albert's reference frame".

    We can avoid this issue by simply acknowledging the mathematical reference frames for what they are; attempted descriptions of physical events.

    We can say that S' says that that the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is physically located on the embankment. We can say that this is what a relatively moving observer will, supposedly, measure. We can then relate these back to the physical world. Given our postulate, we know how Albert's brain will process photons which physically make contact with his retinae, while he is standing on the embankment. If the description of events, as given by S', correspond to physical events, then Albert's brain should process them as a non-simultaneous event. In other words, if the relatively moving observers measurements, of the photons which physically strike Albert's retinae, accurately correspond to physical events i.e. if the photons do physically strike Albert's retinae in the order of one first, then the other, while he is physically standing on the embankment, then we know how his brain should process them, to form Albert's experience.

    citrus burst wrote: »
    The only issue so far that we have encountered is your comments in the previous.

    The issue isn't addressed when we say Albert isn't "in" S. He might as well be. He's on an embankment on the earth. Earth can be moving at any arbitrary speed, but we might as well say its not moving, because we'll have to "add" its initial speed onto the relatively moving observer.

    We use the tags S and S' to show that they are in different frames. The photons physically hit his eyes on the earth. This is described by S. The photons then have to travel to S', in order to be observed by the relatively moving observer. Due to the motion of S' the light will be received differently then how it was received in S. But like you said we don't care about how S' observed the light.
    We don't care about how the observer on the train will observe the light, we are interested in what the observer on the train says about how the photons will physically strike Albert's retinae, while Albert is standing on the embankment. Does his description of events correspond to the physical world? He says that the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is standing on the embankment. If the photons physically strike Albert's retinae in the order of one first, then the other, while he is standing on the embankment, then given our postulate, his brain will process an experience where light flashes from one direction first, then the other.



    citrus burst wrote: »
    Ok, but, why are we sometimes interested?
    ...
    So now we are interested in S' again? It is accurate and does correspond to the physical world.
    ...
    So now we are not interested in S'?
    We are interested in how S' corresponds to the physical; that is, the physicality of the photon striking events, because we know how Albert's brain will process photons which physically strike his retinae.

    citrus burst wrote: »
    So does mine, and it also follows your postuale.
    Sorry, I'm not sure what you mean by "so does mine", do you mean, "so does my brain [process photons in the order they are received]?

    citrus burst wrote: »
    So now we are interested in S' again? You've got to remember that for S' the light hits Albert and then gets detected by S'. It has a longer path to take then in S. Albert gets hit in the reference frame, as described mathematically by S.
    Yes, but S' says that Albert's retinae get struck in the order of one first then the other; if this is physically accurate, then Albert's brain will process them in that order.

    citrus burst wrote: »
    No they are described by them. Language is no way tied to the letters that are used to describe it, yet you don't seem to be debating it.
    We could debate the issue of language, but I don't think we need to; we can stick to talking about reference frames and how they correspond to the physical world.

    citrus burst wrote: »
    So what you are saying does the moon, which is moving relative to the earth affect, my measurement, on earth? Since the moon measures an event that was simultaneous on earth not simultaneous due to its relative motion?
    We are interested in how your brain processes your experiences, and what affects your experiences is how sensory information is taken in by your sensory organs; for example, how photons physically strike your retinae. If an observer on the moon says that photons physically strike your retinae in the order of one first, then the other, then this will have direct consequences for how your brain processes those photons; assuming the measurements of the observer on the moon correspond to physical events; that is, if he says photons physically strike your retinae in the order of one first then the other, while you are standing in your front garden, and if his measurement accurtely reflect the physical world, then your brain should process the photons in that order, to produce your experience.


    citrus burst wrote: »
    I would take exception to the line "If the events as described by S' are physical, then it means that photons physically strike Albert's retinae in the order of one first then the other; if this is true, then Albert's retinae will process them in that order, and produce a non-simultaneous experience."

    How did you deduce this? Well not deduce, how did you put these two together and get 4? Please try and explain this to me
    We start with our postulate, which tells us how Albert's brain processes photons which physically strike his retinae, while he is standing on the embankment.

    S' says that the photons physically strike his retinae in the order of one first, then the other, while he is standing on the embankment.

    If the events, as described by S', correspond to the physical world; that is, if photons strike Albert's retinae in the order of one first, then the other, while he is standing on the embankment, then given our postulate, Albert's brain should process them in the order of one first, then the other, and produce an ordered experience.


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  • #82
    citrus burst
    Registered Users, Registered Users 2 Posts: 147 ✭✭citrus burst


    So lets get some common ground. S says that the two photons hit Albert's eyes simultaneous? Albert's memories reflect this as per the postulate?

    S' is moving relative to S?

    S' detects one photon before the other, after they have reflected off Albert's eyes?

    Somehow Albert's memories are affected by this?

    I would like to add in another observer in Albert's frame, or as you like, standing next to Albert. Or at least, have Albert observing something.
    roosh wrote: »

    The breaking plate example is somewhat different to the question we are considering, but it isn't one that is disputed.
    This was just to show that we can trust Albert's memory.
    roosh wrote: »
    We don't need to lend more physical structure to the mathematical co-ordinates, I think that is part of the underlying issue. We can treat the mathematical co-ordinate systems as they are, a means of describing what occurs in those physical reference frames you mention, the car, the boat, the spaceship etc. It can cloud our reasoning if we don't make this distinction, because we start to make statements such as "it occurs in this reference frame but not in that"; this is made clearer when we talk about photons making physical contact with the retinae of an observer. If we say they make physical contact in a certain order in one reference frame, but not in the other, then we are suggesting that an observers retinae can be both in a reference frame and not in a reference frame.
    Well we need to make the distinction that some things are moving relative to other things. We can do it whatever we're comfortable with.

    I assume the photons make contact with some sort of detector, can be detected by all all observers etc.
    roosh wrote: »
    If we say they make physical contact in a certain order in one reference frame, but not in the other, then we are suggesting that an observers retinae can be both in a reference frame and not in a reference frame.

    Sorry can you clarify what you mean by this?
    roosh wrote: »
    When we make explicit reference to the physical location of the observer we can avoid this conflation. When we say that one reference frame describes the physical events in such a way that it says the photons make physical contact with the observers retinae, in the order of one first then the other, while he is standing on the embankment, then we can make deductions based on what we know about how an observers brain will process photons which physically strike the observers retinae i.e. in the order that they physically hit the retinae.
    And treat their observations correctly.
    roosh wrote: »
    Indeed, S' says that, while Albert is physically standing on the embankment, photons physically strike his retinae in the order of one first, then the other. Given our postulate, we know how Albert's brain should process any photons, which make physical contact with his retinae, to produce his experience, while he is standing on the embankment
    S also says he is standing on the embankment. But S says that they "physically" strike his retinas simultaneous.
    roosh wrote: »
    If the events as described by S' are real, physical, valid, or however we wish to describe them; if they correspond to the physical world, then it means that photons physically strike Albert's retinae in the order of one first, then the other, while he is physically standing on the embankment. If this is true, given our postulate, we know how Albert should process photons which physically strike his retinae, while he is standing on the emabnkment.
    But this leads nothing to your argument.

    roosh wrote: »
    What we can also deduce, and which is the important point for the issue in question, is that the photons from one laser physically struck his retinae in the order of A first, then then B.
    No they physically struck each other at the same time.
    roosh wrote: »
    We're not interested in the timing because there are a near infinite range of time values which can result in a given order of events, we are only interested in the order in which the photons make physical contact with Albert's retinae, because we know that is how his brain will process them.
    Fair enough
    roosh wrote: »
    True for all photons which make physical contact with an observers retinae?
    Yes, I guess.
    roosh wrote: »
    I would be more inclined to say that (x,t) depend on the order; that is, I would ascribe the causal influence to the physical events, not the mathematical co-ordinates.
    But as we are debating, order is relative to velocity.
    roosh wrote: »
    The logic is quite simple. We have the agreed postulate which tells us how Albert's brain will process all photons which make physical contact with Albert's retinae, while Albert is physically standing on the embankment; that is, in the order they make phyiscal contact with his retinae.
    At this point, I'm just going to stop and throw in another postulate. Albert's brain stops detecting photons after they are detected. This ok?
    As in it only detects a photon once.

    So in this case. Laser fired, hits Albert's eye, detected, some is reflected and detected by S'.
    roosh wrote: »
    S' says that the photons make physical contact with Albert's retinae, in the order of one first, then the other, while Albert is physically standing on the embankment. If this is valid, then Albert's brain should process them in that order, given the agreed upon postulate.
    Yes but if we use are new postulate, Albert's brain stop detecting the photons before they reached S'.
    roosh wrote: »

    This is just highlighting the issue of making such statements as "the photons strike Albert's retinae simultaneously 'in Albert's reference frame'" or "the photons strike Albert's retinae non-simultaneously 'not in Albert's reference frame'".
    Ok
    roosh wrote: »
    If Albert is in Albert's reference frame, then so are his retinae; if photons physically strike his retinae then they necessarily strike them "in Albert's reference frame". So if S' says they strike Albert's retinae non-simultaneously, then they must, necessarily, strike Albert's retinae non-simultnaeously "in Albert's reference frame" if Albert and his retinae are "in Albert's reference frame".
    No they are detected none simultaneous.
    roosh wrote: »
    We can avoid this issue by simply acknowledging the mathematical reference frames for what they are; attempted descriptions of physical events.
    Or we could avoid this issue, by only using mathematical reference frames. You assume the problem arises from the use of them, after reading "physically strike Albert's retinae in the order of one first" 30+ times in one post it gets a bit tiresome and we can be forgiven for taking short cuts like using S instead of "Albert's rest frame"
    roosh wrote: »
    We can say that S' says that that the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is physically located on the embankment. We can say that this is what a relatively moving observer will, supposedly, measure. We can then relate these back to the physical world. Given our postulate, we know how Albert's brain will process photons which physically make contact with his retinae, while he is standing on the embankment. If the description of events, as given by S', correspond to physical events, then Albert's brain should process them as a non-simultaneous event. In other words, if the relatively moving observers measurements, of the photons which physically strike Albert's retinae, accurately correspond to physical events i.e. if the photons do physically strike Albert's retinae in the order of one first, then the other, while he is physically standing on the embankment, then we know how his brain should process them, to form Albert's experience.
    But if we use postulate 2, Albert's brain stopped detecting the photons after they hit his eye.
    roosh wrote: »

    We don't care about how the observer on the train will observe the light, we are interested in what the observer on the train says about how the photons will physically strike Albert's retinae, while Albert is standing on the embankment. Does his description of events correspond to the physical world? He says that the photons physically strike Albert's retinae in the order of one first, then the other, while Albert is standing on the embankment. If the photons physically strike Albert's retinae in the order of one first, then the other, while he is standing on the embankment, then given our postulate, his brain will process an experience where light flashes from one direction first, then the other.
    Well, now how on observer on a train, observes the light will directly influence what they say about how the light physically strikes Albert. Do you agree with this? He says what he says, because he "physically" receives the information in a certain order, just like Albert. So his observations can't really be thrown away because they don't fit your argument. In fact I think this is the missing link.

    roosh wrote: »

    We are interested in how S' corresponds to the physical; that is, the physicality of the photon striking events, because we know how Albert's brain will process photons which physically strike his retinae.
    Well if we assume postulate 1 is right, S' will process the information like Albert process information, in the order it is received.
    roosh wrote: »
    Sorry, I'm not sure what you mean by "so does mine", do you mean, "so does my brain [process photons in the order they are received]?
    I meant my brain follows postulate 1.
    roosh wrote: »
    Yes, but S' says that Albert's retinae get struck in the order of one first then the other; if this is physically accurate, then Albert's brain will process them in that order.
    But S says that the light hit Albert's simultaneous, and as such Barry's brain will process the information as such, if this is physically accurate.

    roosh wrote: »


    We start with our postulate, which tells us how Albert's brain processes photons which physically strike his retinae, while he is standing on the embankment.
    Yes
    roosh wrote: »
    S' says that the photons physically strike his retinae in the order of one first, then the other, while he is standing on the embankment.
    Yes
    roosh wrote: »
    If the events, as described by S', correspond to the physical world; that is, if photons strike Albert's retinae in the order of one first, then the other, while he is standing on the embankment, then given our postulate, Albert's brain should process them in the order of one first, then the other, and produce an ordered experience.
    No


  • #83
    dlouth15
    Registered Users, Registered Users 2 Posts: 1,169 ✭✭✭dlouth15


    I would suggest a simplified version of the above. Instead of two eyes and a brain we have two photodetectors connected by two wires to a central unit that emits a flash of light when an electrical signal is simultaneously (and only simultaneously) received from the two photodetectors.

    This is oriented as below
    S' (the moving frame)

y
^
|
|        d'      d'
|    %-------*-------%
|
|
O'-----------------------------------> x

Velocity V--->
    The two light detectors (%) are at a distance d' from the light flasher (*).

    The whole frame moves with velocity V relative to a stationary frame and the electrical signal travels with velocity v' as measured in the moving frame.

    To an observer in the moving frame S' light simultaneously hits the detectors and two electrical signals travel towards the centre. The two signals arrive simultaneously and the flash goes off.

    Now the question is what happens when observed from the stationary frame?

    Roosh, is this a reasonable simplification?


  • #84
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    citrus burst wrote: »
    So lets get some common ground. S says that the two photons hit Albert's eyes simultaneous? Albert's memories reflect this as per the postulate?

    S' is moving relative to S?

    S' detects one photon before the other, after they have reflected off Albert's eyes?

    Somehow Albert's memories are affected by this?
    No, Albert's memories are affected by the order in which the photons physically make contact with his retinae.

    The relatively moving observer doesn't just say that the light reflected from Albert's eyes arrives at him, the relatively moving observer, non-simultaneously, he says that the light hits Albert's eyes in the order of one first, then the other, and is reflected in that order.
    citrus burst wrote: »
    I would like to add in another observer in Albert's frame, or as you like, standing next to Albert. Or at least, have Albert observing something.
    By all means.
    citrus burst wrote: »
    This was just to show that we can trust Albert's memory.
    Ah, OK; yes, we can idealise Albert so that his memories and experiences are infallible; or we can replace him with a less complicated, but more precise machine; I just think it helps to personalise the issue, because it can make the consequences more tangible.
    citrus burst wrote: »
    Well we need to make the distinction that some things are moving relative to other things. We can do it whatever we're comfortable with.

    I assume the photons make contact with some sort of detector, can be detected by all all observers etc.
    Indeed, "things" move relative to other "things", not relative to mathematical co-ordinates. As long as this is reflected in our reasoning there shouldn't be an issue.

    citrus burst wrote: »
    Sorry can you clarify what you mean by this?
    It might be easier to address this point with a question; if Albert's retinae are in S - because Albert is an observer in S - how can photons physically strike his retinae and those events don't occur in S?

    Bearing in mind that the measurements of S', say, supposedly correspond to the physical world and imply that the photons physically strike Albert's retinae in the order of one first, then the other.

    citrus burst wrote: »
    And treat their observations correctly.
    Yes, by relating them back to the physical world.

    citrus burst wrote: »
    S also says he is standing on the embankment. But S says that they "physically" strike his retinas simultaneous.
    Indeed, this is why Albert should have discordant experiences, and why the apparent paradox arises.

    citrus burst wrote: »
    But this leads nothing to your argument.
    If we know how Albert's brain processes photons which physically strike his retinae, we then only need to know the order in which photons physically strike his retinae.

    S' says the strike in the order of one first, then the other, S says they strike together, "tied for first place"; given how Albert's brain processes photons which physically strike his retinae, this should lead to discordant experiences.


    citrus burst wrote: »
    No they physically struck each other at the same time.
    Look at the formulation again, we are talking prior to the original thought experiment where Albert sees the flashes simultaneously; in this pre-experiment testing of the lasers, he sees the flashes happen in the order of one first, then the other; this means that the photons struck his retinae in that order, not together.

    citrus burst wrote: »
    Yes, I guess [it's true for all photons which make physically contact with an observers retinae].
    S' says that the photons make physical contact with Albert's retinae in the order of one first, then the other; so his brain should process an ordered experience which reflects this.
    citrus burst wrote: »
    But as we are debating, order is relative to velocity.
    Not necessarily, because we can consider two photons which arrive in the given order "in Albert's rest frame", where the velocity of a relatively moving observer doesn't matter; this is just to establish how Albert's brain processes photons which make physical contact with his retinae.

    citrus burst wrote: »
    At this point, I'm just going to stop and throw in another postulate. Albert's brain stops detecting photons after they are detected. This ok?
    As in it only detects a photon once.
    I don't see any real problem with this, as long as it doesn't lead to us having to consider photons which physically hit Albert's retinae "in one frame", as being different to photons which strike Albert's retinae "in a different reference frame".

    citrus burst wrote: »
    So in this case. Laser fired, hits Albert's eye, detected, some is reflected and detected by S'.
    Yes, but S' says that the photons physically hit Albert's retinae in the order of one first, then the other, and were reflected in that order.

    If they physically hit Albert's retinae in that order, then his brain will process them as an ordered experience.
    citrus burst wrote: »
    Yes but if we use are new postulate, Albert's brain stop detecting the photons before they reached S'.
    Albert's brain doesn't process photons which strike the retinae of a relatively moving observer.

    That is part of the problem with saying "before they reached S'"; S' isn't something physical which the photons reach; S' describes the physical events mathematically. "Albert" is also "in" S', to the extent that he is represented by co-ordinates in S'.

    citrus burst wrote: »
    No they are detected none simultaneous.
    S' says that the photons physically strike Albert's retinae non-simultaneously, or at least, he calculates that they do; by taking the flight time of the light reflected from Albert's retinae. If his measurements are correct, then the conclusion is that the photons physically struck Albert's retinae in the order of one first, then the other.
    citrus burst wrote: »
    Or we could avoid this issue, by only using mathematical reference frames. You assume the problem arises from the use of them, after reading "physically strike Albert's retinae in the order of one first" 30+ times in one post it gets a bit tiresome and we can be forgiven for taking short cuts like using S instead of "Albert's rest frame"
    I could empathise alright, but the issue is that taking such short cuts can cloud our reasoning; we need to be clear on what it is that is being said.
    citrus burst wrote: »
    But if we use postulate 2, Albert's brain stopped detecting the photons after they hit his eye.
    Indeed, but S' says they physically struck Albert's retinae in the order of one first, and then the other, and that they were refelected in this order. The order in which they physically strike Albert's retinae determines his experiences.
    citrus burst wrote: »
    Well, now how on observer on a train, observes the light will directly influence what they say about how the light physically strikes Albert. Do you agree with this? He says what he says, because he "physically" receives the information in a certain order, just like Albert. So his observations can't really be thrown away because they don't fit your argument. In fact I think this is the missing link/
    But he calculates back and determines, on the basis of his measurements, that the events, which were simultaneous in S, are non-simultaneous in S'; that is, his measurements lead him to the conclusion that the photons physically struck Albert's retinae in the given order.

    If they didn't physically strike Albert's retinae in the given order, then the relatively moving observers observation of non-simultaneous events is an optical illusion.

    citrus burst wrote: »
    Well if we assume postulate 1 is right, S' will process the information like Albert process information, in the order it is received.
    Indeed, the observer in S' will; but if the description of events, or the calucations that the observer in S' performs are deemed to be accurate, then the implication is that the photons physically struck Albert's retinae in the given order; if they struck Albert's retinae in that order, then Albert's brain will process an ordered experience.

    citrus burst wrote: »
    I meant my brain follows postulate 1.
    Ok, I was thinking that, but wasn't 100% on it.
    citrus burst wrote: »
    But S says that the light hit Albert's simultaneous, and as such Barry's brain will process the information as such, if this is physically accurate.
    Barry's brain won't process photons which hit Albert's retinae, only phtons which hit his; if photons hit his retinae simultaneously, then his brain will process a simultaneous experience - that would just represent the other side of the same paradox-coin.


    citrus burst wrote: »
    No
    Why not, it follows from our postulate.


  • #85
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    dlouth15 wrote: »
    I would suggest a simplified version of the above. Instead of two eyes and a brain we have two photodetectors connected by two wires to a central unit that emits a flash of light when an electrical signal is simultaneously (and only simultaneously) received from the two photodetectors.

    This is oriented as below
    S' (the moving frame)

y
^
|
|        d'      d'
|    %-------*-------%
|
|
O'-----------------------------------> x

Velocity V--->
    The two light detectors (%) are at a distance d' from the light flasher (*).

    The whole frame moves with velocity V relative to a stationary frame and the electrical signal travels with velocity v' as measured in the moving frame.

    To an observer in the moving frame S' light simultaneously hits the detectors and two electrical signals travel towards the centre. The two signals arrive simultaneously and the flash goes off.

    Roosh, is this a reasonable simplification?
    Hey dlouth, we can simplify it using the observer also; we can idealise the observer to say that this is how his brain functions; that there is a "centre of processing" where signals from the retinae must travel to to be processed, with the dimensions of your circuit above.

    Personally, I think it helps to make it a bit more tangible if we speak about the experiences produced by the brain; even if it is an idealised version of it. We could perhaps speak about an observer having been cryogenically frozen and then being re-animated in the future, where his visual network is replaced by this simplistic circuitry.

    dlouth15 wrote: »
    Now the question is what happens when observed from the stationary frame?
    This is the issue; we're not interested in how a relatively moving observer will measure Albert's brain activity, or the conclusion he will draw about Albert's experiences; we are interested in how Albert's brain processes photons which physically make contact with his retinae. We know that his brain processes them in the order they make physical contact with his retinae, and this holds true for our simplified visual network.

    The only pertinent question then is, do the photons physically strike his retinae in the order of one first, and then the other, while he is standing on the embankment? If they do, then his brain will process them as an ordered experience.


  • #86
    dlouth15
    Registered Users, Registered Users 2 Posts: 1,169 ✭✭✭dlouth15


    roosh wrote: »
    Hey dlouth, we can simplify it using the observer also; we can idealise the observer to say that this is how his brain functions; that there is a "centre of processing" where signals from the retinae must travel to to be processed, with the dimensions of your circuit above.

    Personally, I think it helps to make it a bit more tangible if we speak about the experiences produced by the brain; even if it is an idealised version of it. We could perhaps speak about an observer having been cryogenically frozen and then being re-animated in the future, where his visual network is replaced by this simplistic circuitry.
    I've no problem with that. The important thing is that we've reduced it to three spacetime events. 1) the left detector firing; 2) the right detector firing and 3) the central point receiving the signals.
    This is the issue; we're not interested in how a relatively moving observer will measure Albert's brain activity, or the conclusion he will draw about Albert's experiences; we are interested in how Albert's brain processes photons which physically make contact with his retinae. We know that his brain processes them in the order they make physical contact with his retinae, and this holds true for our simplified visual network.

    The only pertinent question then is, do the photons physically strike his retinae in the order of one first, and then the other, while he is standing on the embankment? If they do, then his brain will process them as an ordered experience.
    I agree. If light hits one retina and then the other in Albert's frame (whether stationary or moving), he will experience two events. This is because the eyes, the transmission mechanism and the brain (which we're considering to be point-like) are all fixed within Albert's frame.


  • #87
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    dlouth15 wrote: »
    I've no problem with that. The important thing is that we've reduced it to three spacetime events. 1) the left detector firing; 2) the right detector firing and 3) the central point receiving the signals.
    Cool.
    dlouth15 wrote: »
    I agree. If light hits one retina and then the other in Albert's frame (whether stationary or moving), he will experience two events. This is because the eyes, the transmission mechanism and the brain (which we're considering to be point-like) are all fixed within Albert's frame.
    Photons don't physically strike Albert's retinae "in 'Albert's' reference frame", because "Albert's reference frame" is a set of mathematical co-ordinates which don't exist a priori in nature. Photons only physically strike Albert's retinae in the physical world, where Albert is standing on the embankment.

    The mathematical reference frames [attempt to] describe events in the physical world; "Albert's reference frame", or S, says that the photons physically strike Albert's retinae together, or "tied for first place", while Albert is standing on the embankment; "not Albert's reference frame", or S', says that the photons physically strike Albert's retinae in the order of one first then the other, while Albert is standing on the embankment.


    In the physical world, Albert's brain processes photons, which physically strike his retinae, in the order they strike his retinae, while he is standing on the embankment.

    S' says that the photons physically strike his retinae in the order of one first, then the other, while he is physically standing on the embankment; if the description given by S' corresponds to the physical world, such that the photons do physically strike his retinae in the order of one first then the other, while he is standing on the embankment, then his brain will process an ordered experience.


  • #88
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    Apologies, I forgot to reply to this post.

    We don't need to reference any reference frames initially, we can just establish how Albert's brain processes physical stimuli. We know that, while Albert is physically standing on the embankment, his brain will process all photons, which physically strike his retinae, in the order they are received; that is, if photons physically strike his retinae in the order of one first then the other, while he is standing on the embankment, his brian will process them in that order.

    The above is not true, as the order is reference-frame dependent. Instead, it is the causal structure of events that defines what Albert perceives. All reference frames agree on the causal structure of events.


  • #89
    dlouth15
    Registered Users, Registered Users 2 Posts: 1,169 ✭✭✭dlouth15


    roosh wrote: »
    Cool.


    Photons don't physically strike Albert's retinae "in 'Albert's' reference frame", because "Albert's reference frame" is a set of mathematical co-ordinates which don't exist a priori in nature. Photons only physically strike Albert's retinae in the physical world, where Albert is standing on the embankment.

    The mathematical reference frames [attempt to] describe events in the physical world; "Albert's reference frame", or S, says that the photons physically strike Albert's retinae together, or "tied for first place", while Albert is standing on the embankment; "not Albert's reference frame", or S', says that the photons physically strike Albert's retinae in the order of one first then the other, while Albert is standing on the embankment.


    In the physical world, Albert's brain processes photons, which physically strike his retinae, in the order they strike his retinae, while he is standing on the embankment.

    S' says that the photons physically strike his retinae in the order of one first, then the other, while he is physically standing on the embankment; if the description given by S' corresponds to the physical world, such that the photons do physically strike his retinae in the order of one first then the other, while he is standing on the embankment, then his brain will process an ordered experience.
    Could you draw a simple diagram for your setup? I think the problem is easy to solve but I don't want to get bogged down in confusion over this or that detail. The thread is a bit hard to follow.


  • #90
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    dlouth15 wrote: »
    Could you draw a simple diagram for your setup? I think the problem is easy to solve but I don't want to get bogged down in confusion over this or that detail. The thread is a bit hard to follow.
    The diagram you drew is perect; we just need to relate it back to the physical world. Imagine that your '%' are Albert's retinae and the '*' is the "processing centre" of the brain, in Albert's futuristic visual network. We then just need to imagine Albert standing on an embankment and then imagine two photons physically striking his retinae; where they come from is not necessarily important, all that is important is the order in which they physically strike the retinae.


    I'm guessing your solution is to say that, from the perspective of a relatively moving observer, the signals from the retinae will converge on the processing centre simultaneously, even if they strike the retinae asynchronously. The issue is that we aren't interested in how a relatively moving observer will, supposedly, measure Albert's brain activity, or the conclusion he will, supposedly, arrive at with regards to Albert's experience.


    What we are interested in is how Albert's brain processes Albert's experiences, or more pointedly, how Albert's brain will process photons which physically strike his retinae, while he is standing on the embankment.

    We know that Albert's brain will process photons which physically strike his retinae, while he is standing on the embankment, in the order they physically strike his retinae; because this is how Albert's brain processes Albert's experiences in the physical world - as opposed to what a relatively moving observer will, supposedly, measure.


    S' says that the photons physically strike Albert's retinae in the order of one first, then the other, while he is physically standing on the embankment; if this is accurate, then Albert's brain will process an ordered experience.


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  • #91
    citrus burst
    Registered Users, Registered Users 2 Posts: 147 ✭✭citrus burst


    roosh wrote: »
    But he calculates back and determines, on the basis of his measurements, that the events, which were simultaneous in S, are non-simultaneous in S'; that is, his measurements lead him to the conclusion that the photons physically struck Albert's retinae in the given order.

    Think about what you are saying here. Barry in S' receives information about an event that was at rest to him. Uses some means to determine, how that event happened, in the place that is at rest to him. Therefore reasons that this is wrong and he is right, since this is how he measured it. That Albert's measurement of simultaneous light strikes was incorrect and his was correct. That Albert's measurement is invalid, because Barry is in a "special frame" of higher importance then Albert's. That Albert's memories should follow that he was not, in fact blinded in both eyes, but rather in one first, then the other, despite, what Albert thinks.

    This is to me is a big hole in your argument. You have put one reference frame on a plate and declared it special. You may not have meant it, but from your explanation, you have confirmed it. This is in contradiction to what Galileo, Newton and later Einstein did and said that all reference frames are equal. Special relativity postulate one.

    What actually happens is Barry, in S', receives information from S, that the light struck Albert's eyes non-simultaneous, according to his reference frame. He then calculates back, knowing the speed he is moving relative to Albert and the timing between the two light strikes, that in Albert's frame S, the light "physically" hit Albert simultaneously, as per what Albert measured. There is no contradiction between Albert's memories and his measurements.

    roosh wrote: »
    If they didn't physically strike Albert's retinae in the given order, then the relatively moving observers observation of non-simultaneous events is an optical illusion.
    See optical illusion is a bad choice of words and makes me laugh. How can what our number one sensory organ detect be an "illusion." It gets the information, its up to the brain to process the information. Its the brain that makes false conclusions, that seem to cause the optical illusion.

    The classic example being a mirage. The optical illusion is that the brain thinks it sees water. What it actually see's is the reflection of the sky, but it determines it is water, in a vain attempt to save its life.

    The illusion in this case, I guess is that we think that events are simultaneous for us, should be simultaneous for everywhere. But due to the finite speed of light, this might not the case.

    Its unintuitive, and it should be. Its not an "optical illusion" but a part of the universe's nature.
    roosh wrote: »
    Indeed, the observer in S' will; but if the description of events, or the calucations that the observer in S' performs are deemed to be accurate, then the implication is that the photons physically struck Albert's retinae in the given order; if they struck Albert's retinae in that order, then Albert's brain will process an ordered experience.
    See above for proper treatment of reference frames and measurement.
    roosh wrote: »
    Barry's brain won't process photons which hit Albert's retinae, only phtons which hit his; if photons hit his retinae simultaneously, then his brain will process a simultaneous experience - that would just represent the other side of the same paradox-coin.

    Well I was assuming that some of the photons, bounce of Albert's eyes, in order to be detected by another reference frame. If all the photons fired by the laser were detected by Albert, then the whole experiment would be null and void.

    I don't like that we use Albert as both a detector and an observer, it adds a certain complication that we don't really need.

    I'd prefer to have one laser, that's beam is split and reflected by two mirrors. The light from the two lasers is redirected to two arbitrary points that are equidistant apart. The whole point of the set up is to make sure that the beams are in phase with each other and travel the same distance.

    Then Albert, in the same frame as the set up, using some experimental set up, determines the time interval between the light from the two beams hitting the two arbitrarily chosen points.

    Barry, moving relative to Albert also has an identical set up to Albert to determine the time interval between the two beams hitting the two arbitrary points.


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