Question on Lorentz transforms and relativity of simultaneity

dlouth15

roosh wrote: »

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.

OK so the apparatus with the two detectors is stationary in a frame S and there is a moving frame S'. Is that the correct setup? I'll assume it is.

From the point of view of the stationary frame there is no problem and the two detectors will be activated simultaneously and the electrical signal will travel towards the centre and activate the central processing unit.

From the point of view of the S' (moving relative to S), the detectors will fire non-simultaneously, however applying the Lorentz transformation, the velocities of the electrical signals as well as the lengths those signals have to travel will be transformed in such a way that the signals still arrive at the central point at the same time. The central processing unit still flashes.

Therefore even though the light detectors viewed from S' are activated at different times, the observer in S' can see that Albert still perceives the events as simultaneous (i.e. the flash)

Now does any of this violate causality or physicality or whatever? No. It would only violate causality if either or both of the light detection events occurred before the flash. But this does not happen under the Lorentz transformation.

The other thing that would violate physicality would be if the any signal was observed to be travelling faster than the speed of light. Again this does not happen under the Lorentz transformation.

Every observer in every frame sees a plausible physical situation.

roosh

citrus burst wrote: »

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.

There is no need to treat any reference frame as special; the whole issue arises because we treat the description of retinae striking events, given by both reference frames as equally real, or equally physical.

As we have mentioned before, reference frames, of the type S and S', are mathematical depictions of physical events; observers are not phyiscally "in" the mathematical reference frames, the mathematical reference frames represent the physical observers using a set of co-ordinate labels. So Albert isn't in a "special frame", Albert is physically located on the embankment; this is only "special" to the degree that it represents the physical scenario.

S and S' describe event which physically happen to Albert, while he is physically standing on the embankment. There are certain things we know about how Albert's brain produces Albert's experiences, when photons physically strike his retinae. Using the information about the physical retinae striking events, from both S and S' - which we treat as being equally phyiscal - we can deduce how Albert's brain would process such events, because we know how his brain operates in the physical world; not some "special" mathematical reference frame.

Again, the issue appears to be that you are talking about how a relatively moving observer will, supposedly, measure Albert's brain activity and the conclusion he will, supposedly, draw about Albert's experience. We're not interested in that though, we're interested in how Albert's brain processes photons which physically strike his retinae, while he is standing on the embankment; we're interested in the physicality of the retinae striking events, as described by the mathematical reference frames; and we're interested in the order in which the photons physically strike Albert's retinae.

citrus burst wrote: »

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.

Again, Albert and Barry aren't physically "in" S and S', respectively; Albert is physically on the embankment and Barry is physically on the train; S and S' are mathematical representations of the physical events, which [are supposed to] aid both observers in any calculations they might try to make.

The description of events given by S', be they caluclations, measurements or whatever form they take, says that the photons physically strike Albert's retinae while he is physically standing on the embankment, in the order of one first, then the other; if this description corresponds to physical events, such that Albert's retinae are struck in the given order, while he is standing on the embankment, then Albert's brain will process them in that order; because that is how Albert's brain operates in the physical world, to produce Albert's experiences.

citrus burst wrote: »

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.

We can try and find another phrase if needs be, but I think serves the intended purpose here.

citrus burst wrote: »

Its unintuitive, and it should be. Its not an "optical illusion" but a part of the universe's nature.

And the nature of the brain is to process photons which physically strike an observer's retinae in the order they are received, when that observer is standing on an embankment, say, in the physical world.

citrus burst wrote: »

See above for proper treatment of reference frames and measurement.

See replies.

citrus burst wrote: »

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 understood that, but that wasn't what the statement said:

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 the information "as such", where "as such" means that light hits Albert's retinae simultaneously. The information that Barry's brain will process will be from the photons which physically impact his own retinae.

It doesn't matter either way, we are only interested in the physicality of the photons which strike Albert's retinae, and the order in which they physically strike Albert's retinae. The information that Barry has, says that the photons physically strike Albert's retinae in the order of one first, then the other. If this information is correct, and Albert's retinae are struck in the given order, the we know how Albert's brain will process the photons.

citrus burst wrote: »

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.

The issue is that, in the physical world, Albert is both a detector and an observer; that's the function his senses play; we can idealise Albert such that his senses are infallible, or we can idealise him such that he has been cryogenically frozen and re-animated in the future, with some of his sensory system replaced by infallible machinery.

Personalising it in this manner helps to crystalise it in the mind, I find; it's more difficult to dismiss an experience we ourselves could relate to; it makes it that much less abstract and that much more tangible. It also helps us avoid any philosophical assumptions about clocks and time.

citrus burst wrote: »

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.

I was thinking of a somewhat different thought experiment also, that didn't necessarily involve an observers experience, but I don't think it is neecssary. We can idealise Albert and stick with him; as I mentioned, I think it makes it that much more tangible.

roosh

dlouth15 wrote: »

OK so the apparatus with the two detectors is stationary in a frame S and there is a moving frame S'. Is that the correct setup? I'll assume it is.

I would clarify this somewhat and say that Albert - the apparatus with the two detectors - is standing on the embankment; the mathematical reference frames, S and S', reflect this physical situation; both label him as at rest relative to the platform and in motion relative to Henry, on the train.

citrus burst wrote: »

From the point of view of the stationary frame there is no problem and the two detectors will be activated simultaneously and the electrical signal will travel towards the centre and activate the central processing unit.

From the point of view of the S' (moving relative to S), the detectors will fire non-simultaneously, however applying the Lorentz transformation, the velocities of the electrical signals as well as the lengths those signals have to travel will be transformed in such a way that the signals still arrive at the central point at the same time. The central processing unit still flashes.

Therefore even though the light detectors viewed from S' are activated at different times, the observer in S' can see that Albert still perceives the events as simultaneous (i.e. the flash)

The key point is that we are not interested in how the observer moving relative to Albert will, supposedly, measure Albert's brain function, nor are we interested in the conclusion he will, supposedly, arrive at about Albert's experiences. We are interested in how Albert's brain processes photons which physically strike his retinae, to process his experiences; we know that his brain processes photons which physically strike his retinae in the order in which they physically strike his retinae, while he is standing on the embankment.

We are interested, however, in the physicality of the photon striking events, as described by S'; we are interested in this because we know how Albert's brain will process photons which physically strike his retinae, while he is standing on the embankment.


According to the description of physical event given by S', 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 the photons physically strike Albert's retinae in this order, while he is standing on the embankment, then his brain will process them as an ordered experience.

citrus burst wrote: »

Now does any of this violate causality or physicality or whatever? No. It would only violate causality if either or both of the light detection events occurred before the flash. But this does not happen under the Lorentz transformation.

The other thing that would violate physicality would be if the any signal was observed to be travelling faster than the speed of light. Again this does not happen under the Lorentz transformation.

Every observer in every frame sees a plausible physical situation.

It probably isn't a violation of causality, but extrapolating this to your set-up where the light flashes, it means that the light should both flash and not flash; which would seem to represent a paradox.

citrus burst

roosh wrote: »

I would clarify this somewhat and say that Albert - the apparatus with the two detectors - is standing on the embankment; the mathematical reference frames, S and S', reflect this physical situation; both label him as at rest relative to the platform and in motion relative to Henry, on the train.

So S is the platform and S' is the train?

roosh wrote: »

The key point is that we are not interested in how the observer moving relative to Albert will, supposedly, measure Albert's brain function, nor are we interested in the conclusion he will, supposedly, arrive at about Albert's experiences. We are interested in how Albert's brain processes photons which physically strike his retinae, to process his experiences; we know that his brain processes photons which physically strike his retinae in the order in which they physically strike his retinae, while he is standing on the embankment.

If this is the case, then the light will hit his eyes as per our experiment set up. If the two mirrors are the same distance apart then the light will arrive simultaneous. If we move one of the mirrors, the light will arrive non-simultaneous. And that's pretty much it. Albert's memories are affected as per postulate one.

roosh wrote: »

We are interested, however, in the physicality of the photon striking events, as described by S'; we are interested in this because we know how Albert's brain will process photons which physically strike his retinae, while he is standing on the embankment.

But as you said, we don't care about what an observer in S' says, so S' is null and might as well not exist. Our problem is solved.

roosh wrote: »

According to the description of physical event given by S', 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 the photons physically strike Albert's retinae in this order, while he is standing on the embankment, then his brain will process them as an ordered experience.

But there is nothing in S' to make an observation/measurement and/or we are choosing to ignore it.

roosh wrote: »

It probably isn't a violation of causality, but extrapolating this to your set-up where the light flashes, it means that the light should both flash and not flash; which would seem to represent a paradox.

I don't remember saying this??

Yes the two photons will interfere?

I don't know what you mean

dlouth15

Roosh, I was going to reply to your previous post but I think at this point it would be best if we start again with a clear description of the current setup. It is hard to figure out what is going on by reading through the thread. I'm getting very confused and its a confusing subject to begin with. One thing I think is important is that things are discussed in terms of observable spacetime events (i.e. something that occurs at a particular point at a particular time (wrt whatever frame of reference). A basic picture too will help.

dlouth15

citrus burst wrote: »

I don't remember saying this??

Yes the two photons will interfere?

I don't know what you mean

It was me that said that. I proposed a setup with two light detectors and a central flash that goes when a signal from each arrives at the central point. Unfortunately you were attributed to the quote.

roosh

citrus burst wrote: »

So S is the platform and S' is the train?

The co-ordinates of S are used to describe the position and motion of the relatively moving train, and observer, so S cannot simply refer to the physical platform; similarly, the co-ordinates of S' describe Albert's position on the platform, and the platform itself, so it cannot simply be the train.

citrus burst wrote: »

If this is the case, then the light will hit his eyes as per our experiment set up. If the two mirrors are the same distance apart then the light will arrive simultaneous. If we move one of the mirrors, the light will arrive non-simultaneous. And that's pretty much it. Albert's memories are affected as per postulate one.

Which experimental set-up are you referring to here? The one we've been discussing is where S describes the retinae striking events as simultaneous; the Loretnz transform gives us the co-ordinates of those events in S'; according to S' the events are non-simultaneous; that is, S' says that the photons physically strike Albert's retinae in the order of one first, then the other. If they physically strike his retinae in that order, then that is how his brain will process them.

citrus burst wrote: »

But as you said, we don't care about what an observer in S' says, so S' is null and might as well not exist. Our problem is solved.

We're not interested in how he measures Albert's brain activity, becuase Albert's brain doesn't produce Albert's experiences from the perspective of a relatively moving observer.

We are interested in the physicality of the retinae striking events, however, because Albert's brain does process photons which physically strike his retinae.

citrus burst wrote: »

But there is nothing in S' to make an observation/measurement and/or we are choosing to ignore it.

We can have the light reflect from Albert's retinae to the relatively moving observer, this won't change the fact that S' says the photons physically strike Albert's retinae in the order of one first, then the other. Using only the co-ordinates of S we can get the co-ordinates of S', without any observer necessary, because we can calculate what he would measure; and we calculate that he would conclude that the photons physically strike Albert's retinae in a given order.

citrus burst wrote: »

I don't remember saying this??

Yes the two photons will interfere?

I don't know what you mean

Apologies, it was dlouth that said that; but we can apply his formulation to make the result less observer centred.

We can speak about re-animated Albert, after the cryogenic freezing and the surgery to replace his visual network with dlouths simplistic yet precice network; we can even attach a light bulb to him, such that it switches on if, and only if, the signals from his two retinae arrive at the idealised "processing centre" simultaneously, or "tied for first place"; as opposed to in the order of one first, then the other.

If the photons physically strike his retinae in the order as specified by S', then the light doesn't switch on; if they physically strike in the order specified by S, then it does.

Relativity says both are equally true; that is, that the photons physically strike his retinae in the order of one first, then the other, while he is physically standing on the embankment; and, they physically strike his retinae "tied for first place", while he is physically standing on the embankment.

If this is true then the light should both turn on, and not turn on. We can have it such that it detonates a bomb also, if we want to make it more dramatic; such that a building both gets demolished and doesn't get demolished.

roosh

dlouth15 wrote: »

Roosh, I was going to reply to your previous post but I think at this point it would be best if we start again with a clear description of the current setup. It is hard to figure out what is going on by reading through the thread. I'm getting very confused and its a confusing subject to begin with. One thing I think is important is that things are discussed in terms of observable spacetime events (i.e. something that occurs at a particular point at a particular time (wrt whatever frame of reference). A basic picture too will help.

Hey dlouth, I can understand that it's getting confusing alright. I think it is fair to discuss things by referring to observable spacetime events, as long as we relate it back to the physical world, where the events occur.

Set-up
The set-up is quite simple really, we can take the diagram you drew earlier and say that it represents Albert's replaced visual network - after he was cryogenically frozen and re-animated. We can also attach the light to Albert's head, as per your network, so we can have the best of both worlds.

Essentially, the '%' in your diagram can represent Albert's retinae; the '*' can represent the processing centre which produces both Albert's experience and the signal to switch on the light on Albert's head.


Albert is standing on an embankment, located midway between two lasers, A and B; he is positioned in such a way that his left retina is the same distance from A as his right retina is from B.

Albert's brain
I think it is important to set out how Albert's brain functions, in the physical world, to produce Albert's experiences. As far as Albert's brain is concerned, the time it takes for a signal to travel form % to * (retina to processing centre) is the same for both % (retinae); this is how it produces Albert's experiences, while Albert is physically standing on the embankment.

Albert's brain will process photons which physically strike his retinae, while he is standing on the embankment, in the order they strike his retinae.

Reference frames
The mathematical reference frames, S and S', can be used to describe events which happen in the physical world; the co-ordinates of S can be used to ascertain the co-ordinates of S', using the Lorentz transform, and vice versa.

According to the reference frame S, the photons physically strike Albert's retinae together, or "tied for first place", while Albert is physically standing on the platform.

According to S', the photons physically strike Albert's retinae in the order of one first, then the other, while he is standing on the embankment.

If both of these descriptions correspond to physical events, it means 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; and they physically strike his retinae together, or "tied for first place".

Knowing what we do about how Albert's brain will process photons, which physically strike his retinae while he is standing on the embankment, if both these descriptions represent physical events, then the light on Albert's head should both light up and not light up.

dlouth15

roosh wrote: »

According to S', the photons physically strike Albert's retinae in the order of one first, then the other, while he is standing on the embankment.

If both of these descriptions correspond to physical events, it means 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; and they physically strike his retinae together, or "tied for first place".

Knowing what we do about how Albert's brain will process photons, which physically strike his retinae while he is standing on the embankment, if both these descriptions represent physical events, then the light on Albert's head should both light up and not light up.

How are the two frames S and S' moving relative to Albert?

roosh

dlouth15 wrote: »

How are the two frames S and S' moving relative to Albert?

It depends on what you mean by "Albert".

Albert, the physical observer standing on the embankment, is not moving relative to the co-ordinate labels of either S or S', because those co-ordinate labels do not exist a priori in nature; they're not physical, so physical observers cannot move relative to them.

If you mean the co-ordinate labels which represent Albert in both reference frames, then the co-ordinate labels which represent Albert are labeled as "at rest" relative to the co-ordinate lables which constitue S, but are labeled as "in motion" relative to S'.

Albert is not physically in S or S', because S and S' are not physical; S and S' prime attempt to describe events which happen in the physical world. Albert is physically standing on the embankment, at rest relative to it, and both mathematical reference frames reflect this. The photons do not strike Albert's retinae "in" the mathematical reference frame, the reference frames describe how the photons strike Albert's retinae, while he is standing on the embankment.

S' says 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 the photons physically strike Albert's retinae in that order, while he is standing on the embankment, then his brain will process an ordered experience; because that is how his brain processes photons which physically strike his retinae, in that order.

dlouth15

roosh wrote: »

S' says 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 the photons physically strike Albert's retinae in that order, while he is standing on the embankment, then his brain will process an ordered experience; because that is how his brain processes photons which physically strike his retinae, in that order.

From the perspective of S', yes indeed the light will appear to impinge on the retinaes one after the other. But from this same perspective, the velocities of the signals to the processing area (and the distance they need to travel) will be such that they still arrive at the central point at the same time. So the light will still go on.

Regardless of the frame of reference, Albert always perceives a single event.

Morbert

Roosh, you are ignoring the corrections to the mistake you are making.

Simultaneity is not physical. It is frame-dependent. The claim that the photons struck simultaneously is no more or less physically valid than the claim that the photons struck non-simultaneously. What is physical is the causal relation between events. All reference frames agree with what signals in the brain were induced due to detection, and the interrelations between those signals that cause Albert to experience blindness in both eyes simultaneously.

citrus burst

roosh wrote: »

The co-ordinates of S are used to describe the position and motion of the relatively moving train, and observer, so S cannot simply refer to the physical platform; similarly, the co-ordinates of S' describe Albert's position on the platform, and the platform itself, so it cannot simply be the train.

Here's a crudely drawn picture of what is happening. Let me know if you agree with it

roosh

dlouth15 wrote: »

From the perspective of S', yes indeed the light will appear to impinge on the retinaes one after the other. But from this same perspective, the velocities of the signals to the processing area (and the distance they need to travel) will be such that they still arrive at the central point at the same time. So the light will still go on.

Regardless of the frame of reference, Albert always perceives a single event.

Albert's brain doesn't process photons from that perspective; in the physical world Albert's brain processes photons which physically strike his retinae, in the order they are received, to produce his experiences while he is standing on the embankment.

So, it is a question of whether the photons only "appear" to strike his retinae in the order of one first, then the other, while he is standing on the embankment; or if they physically strike his retinae in the order one first, then the other, while he is physically standing on the embankment; afterall, appearances can be deceptive.

roosh

Morbert wrote: »

Roosh, you are ignoring the corrections to the mistake you are making.

Simultaneity is not physical. It is frame-dependent. The claim that the photons struck simultaneously is no more or less physically valid than the claim that the photons struck non-simultaneously. What is physical is the causal relation between events. All reference frames agree with what signals in the brain were induced due to detection, and the interrelations between those signals that cause Albert to experience blindness in both eyes simultaneously.

The order in which photons physically strike Albert's retinae, while he is physically standing on the embankment - something which will dictate his experience - is most definitely physical. Those are the physical events, which happen in the physical world.

If you are suggesting that the photons do not physically strike his retinae in the order of one first, then the other, while he is physically standing on the embankment, then any reference frame which describes the events in this manner does not correspond to the physical world.

roosh

citrus burst wrote: »

Here's a crudely drawn picture of what is happening. Let me know if you agree with it

your first diagram appears to show Albert facing two lasers which come from the same direction; the set-up we are talking about is similar to the traditional thought experiment where lightning strikes two poles to the left and right of the observer (Albert) in the middle of them.

dlouth15

roosh wrote: »

Albert's brain doesn't process photons from that perspective; in the physical world Albert's brain processes photons which physically strike his retinae, in the order they are received, to produce his experiences while he is standing on the embankment.

So, it is a question of whether the photons only "appear" to strike his retinae in the order of one first, then the other, while he is standing on the embankment; or if they physically strike his retinae in the order one first, then the other, while he is physically standing on the embankment; afterall, appearances can be deceptive.

But it is not the order in which the light strikes the retinas but the order in which the signals pass to the processing unit. If the two signals arrive at the same time then it will be processed as simultaneous. I think this is the nub of the issue.

Morbert

roosh wrote: »

The order in which photons physically strike Albert's retinae, while he is physically standing on the embankment - something which will dictate his experience - is most definitely physical. Those are the physical events, which happen in the physical world.
.

No it is not. This is an elementary feature of the relativity of simultaneity.

http://en.wikipedia.org/wiki/Relativity_of_simultaneity
"In physics, the relativity of simultaneity is the concept that simultaneity–whether two events occur at the same time–is not absolute, but depends on the observer's reference frame."

If you are suggesting that the photons do not physically strike his retinae in the order of one first, then the other, while he is physically standing on the embankment, then any reference frame which describes the events in this manner does not correspond to the physical world.

Close. Any reference frame is an arbitrary labelling of the physical events. As before, the events are physical, the causal relation between them is physical (in this case they are separated by a space-like interval), but the coordinates we use when we label one event happening before the other, or both happening simultaneously, is not physical.

Morbert

dlouth15 wrote: »

But it is not the order in which the light strikes the retinas but the order in which the signals pass to the processing unit. If the two signals arrive at the same time then it will be processed as simultaneous. I think this is the nub of the issue.

We can even generalise this. If a single location for a processing unit is considered too abstract or unphysical, we can consider an extended mesh of neurons connecting different locations of interactions within the brain, and we will get the same result.

Basically, since all reference frames agree on what events in the brain are co-incident (occurring at the same place and time), all reference frames will agree on what interactions occur in the brain, and what conscious experience the brain will produce.

roosh

dlouth15 wrote: »

But it is not the order in which the light strikes the retinas but the order in which the signals pass to the processing unit. If the two signals arrive at the same time then it will be processed as simultaneous. I think this is the nub of the issue.

From the perspective of Albert's brain, the time it takes for each signal to travel from the retina to the processing centre, is the same for each retinae. Albert's brain will process all photons, which physically strike his retinae, in this manner. 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. If this is the case, then his brain will process them in that order.

roosh

Morbert wrote: »

We can even generalise this. If a single location for a processing unit is considered too abstract or unphysical, we can consider an extended mesh of neurons connecting different locations of interactions within the brain, and we will get the same result.

Basically, since all reference frames agree on what events in the brain are co-incident (occurring at the same place and time), all reference frames will agree on what interactions occur in the brain, and what conscious experience the brain will produce.

We can keep as the single location for processing, that doesn't matter; indeed, we can hypothesise that Albert is cryogenically frozen and re-animated in the future, where he has had his visual system replaced with such a simply circuit; we can attach a light to it, as per dlouth's original concetualisation.

This doesn't change the fact that, as far as Albert's brain is concerned, when it is processing the physical stimuli which will result in his experience, the time it takes a signal to travel from the photo-receptor to the processing centre is the same for both retinae. This is how Albert's brain will process all photons which physically strike his retinae.

Bearing in mind that Albert's perspective, or perception, is created by his brain processing photons, for example, which physically strike his retinae. 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 they do physically strike his retinae in this manner, then his brain will process an ordered experience.

Morbert

roosh wrote: »

We can keep as the single location for processing, that doesn't matter; indeed, we can hypothesise that Albert is cryogenically frozen and re-animated in the future, where he has had his visual system replaced with such a simply circuit; we can attach a light to it, as per dlouth's original concetualisation.

This doesn't change the fact that, as far as Albert's brain is concerned, when it is processing the physical stimuli which will result in his experience, the time it takes a signal to travel from the photo-receptor to the processing centre is the same for both retinae. This is how Albert's brain will process all photons which physically strike his retinae.

Bearing in mind that Albert's perspective, or perception, is created by his brain processing photons, for example, which physically strike his retinae. 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 they do physically strike his retinae in this manner, then his brain will process an ordered experience.

[edit]-Ignoring your incorrect use of the word "physical", which I previously addressed in post #109: The time it takes a signal to travel from the photo-receptor to the processing centre is only the same for both retinae in S. In S', it takes longer for one signal to travel from the receptor to the centre than the other.

I should also point out that, if you consider the processing centre to be a single location, my derivation in post #13 can be fairly simply modified to incorporate any retinae.

roosh

Morbert wrote: »

No it is not. This is an elementary feature of the relativity of simultaneity.

http://en.wikipedia.org/wiki/Relativity_of_simultaneity
"In physics, the relativity of simultaneity is the concept that simultaneity–whether two events occur at the same time–is not absolute, but depends on the observer's reference frame."

Photons which physically strike Albert's retinae are physical. If Albert sees a flash of light from the left, and then sees a flash of light from the right, it is because the photons coming from the left physically hit his retinae first and the photons from the right physically hit his retinae second.

If a photon strikes one eye before the other, then we can say they physically strike in the order of one first, then the other. This is how it happens in the physical world, where Albert is physically standing on the embankment.

Morbert wrote: »

Close. Any reference frame is an arbitrary labelling of the physical events. As before, the events are physical, the causal relation between them is physical (in this case they are separated by a space-like interval), but the coordinates we use when we label one event happening before the other, or both happening simultaneously, is not physical.

The physical events are the photons physically striking Albert's retinae, while he is physically standing on the embankment. The reference frames [attempt to] describe these physical world events; that is, the co-ordinate labels are used to represent the physical world events and represent what different observers would, supposedly, measure. The description of events given by both reference frames supposedly correspond to the physical world.

S' describes the physical scenario - of the photons physically striking Albert's retinae - in such a way that the conclusion is 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; that is, the, supposed, measurements of the relatively moving observer, which supposedly correspond to the physical world, imply that the photons physically strike Albert's retinae while he is standing on the embankment.

We know how Albert's brain processes photons which physically strike his retinae, to produce Albert's experience - as opposed to how a relatively moving observer will. supposedly, measure Albert's brain activity and the conclusion he would, supposedly, draw about Albert's experience.

Morbert wrote: »

[edit]-Ignoring your incorrect use of the word "physical", which I previously addressed in post #109:

I'm using the word "physical" to refer to the physical body of Albert physically standing on the physical embankment, in the, so-called, phyiscal world.

Your point above was with regard to the physicality of simultaneity, which has been addressed.

Morbert wrote: »

The time it takes a signal to travel from the photo-receptor to the processing centre is only the same for both retinae in S. In S', it takes longer for one signal to travel from the receptor to the centre than the other.

S and S' are mathematical reference frames, consisting of co-ordinate labels which do not exist a priori in nature; as such, it doesn't take the signals any length of time to travel "in" them, because signals travel in the physical world, not in mathematical reference frames. The mathematical reference frames represent what different observers will, supposedly, measure.

What you are saying here is that a relatively moving observer will, supposedly, measure Albert's brain activity in the manner described above. We're not interested in how a relatively moving observer will, supposedly, measure Albert's brain activity and the conlcusion he would, supposedly, draw about Albert's experience. We are interested in how Albert's brain processes photons which physically strike his retinae, to produce his experiences - from it's own perspective - while he is physically standing on the embankment. This we have established already in the thread.

We are also interested in the physicality of the retinae striking events, because Albert's experiences are determined by the order in which photons physically strike his retinae; and his brain will process photons which physically strike his retinae in the order they physically strike them.

S' says that the photons physically strike in the order of one first, then the other; so Albert's brain should process an ordered experience, because that is how his brain processes all photons which physically strike his retinae, while he is standing on the embankment.

Morbert wrote: »

I should also point out that, if you consider the processing centre to be a single location, my derivation in post #13 can be fairly simply modified to incorporate any retinae.

I should probably point out that the conversation has progressed from there to here, and that would just lead us back to this exchange, because it won't change the nature of the point.

Morbert

roosh wrote: »

Photons which physically strike Albert's retinae are physical. If Albert sees a flash of light from the left, and then sees a flash of light from the right, it is because the photons coming from the left physically hit his retinae first and the photons from the right physically hit his retinae second.

If a photon strikes one eye before the other, then we can say they physically strike in the order of one first, then the other. This is how it happens in the physical world, where Albert is physically standing on the embankment.

The physical events are the photons physically striking Albert's retinae, while he is physically standing on the embankment. The reference frames [attempt to] describe these physical world events; that is, the co-ordinate labels are used to represent the physical world events and represent what different observers would, supposedly, measure. The description of events given by both reference frames supposedly correspond to the physical world.

S' describes the physical scenario - of the photons physically striking Albert's retinae - in such a way that the conclusion is 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; that is, the, supposed, measurements of the relatively moving observer, which supposedly correspond to the physical world, imply that the photons physically strike Albert's retinae while he is standing on the embankment.

We know how Albert's brain processes photons which physically strike his retinae, to produce Albert's experience - as opposed to how a relatively moving observer will. supposedly, measure Albert's brain activity and the conclusion he would, supposedly, draw about Albert's experience.

The events are physical. The simultaneity, or lack-of, between the two events is not physical. This is what you consistently ignore.

S and S' are mathematical reference frames, consisting of co-ordinate labels which do not exist a priori in nature; as such, it doesn't take the signals any length of time to travel "in" them, because signals travel in the physical world, not in mathematical reference frames. The mathematical reference frames represent what different observers will, supposedly, measure.

Now you're just being deliberately truculent. You know well what I mean by "in S".

What you are saying here is that a relatively moving observer will, supposedly, measure Albert's brain activity in the manner described above. We're not interested in how a relatively moving observer will, supposedly, measure Albert's brain activity and the conlcusion he would, supposedly, draw about Albert's experience. We are interested in how Albert's brain processes photons which physically strike his retinae, to produce his experiences - from it's own perspective - while he is physically standing on the embankment. This we have established already in the thread.

We are also interested in the physicality of the retinae striking events, because Albert's experiences are determined by the order in which photons physically strike his retinae; and his brain will process photons which physically strike his retinae in the order they physically strike them.

S' says that the photons physically strike in the order of one first, then the other; so Albert's brain should process an ordered experience, because that is how his brain processes all photons which physically strike his retinae, while he is standing on the embankment.

See, if I were to take your attitude, I would say something like "S' can't say anything. Coordinate labels can't talk." but I won't.

Not only is the bit in blue a non sequitur, it is flat out wrong. What part of the following don't you understand: "All observers agree that Albert's brain will produce an experience of simultaneously being blinded in both eyes."

I should probably point out that the conversation has progressed from there to here, and that would just lead us back to this exchange, because it won't change the nature of the point.

You said in a recent post that you're fine with assuming the brain approximated at a single location. Then my derivation is as relevant as always.

roosh

Morbert wrote: »

The events are physical. The simultaneity, or lack-of, between the two events is not physical. This is what you consistently ignore.

I'm not ignoring it, I'm simply stating what is physically true. If an observer sees a flash of light from one direction first and a subsequent flash of light from the other direction second, then we can conclude that the photons from one source physically struck one retinae first and the photons from the other source physically struck the other retina second, because that is the only way the observers brain could process such an ordered experience.

We can, therefore, say that the photons physically struck the observers retinae in the order of one first, then the other.

If you are talking about a different kind of mathematical simultaneity that doesn't correspond to the physical world, then that just supports the contention being made.

Morbert wrote: »

Now you're just being deliberately truculent. You know well what I mean by "in S".

No, I have mentioned previously that part of the issue is ascribing physical characteristics to mathematical reference frames; statements like "such and such happens in S but not S'" is an example of such; it only serves to cloud the issue.

Morbert wrote: »

See, if I were to take your attitude, I would say something like "S' can't say anything. Coordinate labels can't talk." but I won't.

That would be a case of being deliberately truculent, because making the statement "S' says" is just a short hand way of saying "S' represents the measurements that a relatively moving observer would make, and from these measurements the implication is that"; it doesn't cloud the issue in the manner of saying "in S'".

Morbert wrote: »

Not only is the bit in blue a non sequitur, it is flat out wrong. What part of the following don't you understand: "All observers agree that Albert's brain will produce an experience of simultaneously being blinded in both eyes."

There's nothing in that I don't understand. What part of the following do you not understand:
- we are not interested in how a relatively moving observer would, supposedly, measure Albert's brain activity

- we're not interested in what he would, supposedly, conclude about Albert's experience, and whether or not he would agree.

- we are interested in how Albert's brain processes photons which physically strike his retinae, to produce his experience, in the physical world.

- we know Albert's brain processes photons, which physically strike his retinae, in the order they are received, while he is standing on the embankment.

- we are interested in how the description of the retinae striking events, as described by S', corresponds to the physical world; that is, do photons physically strike Albert's retinae in the order of one first, then the other, while he is standing on the embankment.

- with the two pieces of information - how Albert's brain processes photons which physically strike Albert's retinae, and the physicality of the photon strikes which occur in the order of one first then the other - we can deduce how Albert's brain should process Albert's experience, in the physical world, while he is standing on the embankment; no "in" either S or S'.

Morbert wrote: »

You said in a recent post that you're fine with assuming the brain approximated at a single location. Then my derivation is as relevant as always.

Indeed, and from your derivation we find ourselves here.

EDIT: just to clarify, your derivation is just a mathematical representation of the argument you and others have been making in this thread already; it gives us the co-ordinates for the convergence of the signals on the processing centre in S'. To relate that to the physical example we have been discussing; it is telling us how a relatively moving observer will, supposedly, measure Albert's brain activity and the conclusion he will, supposedly, arrive at about Albert's experience; again, however, we are not intersted in the relatively moving observers opinion on Albert's experience, and whether or not he will agree. We are interested in how Albert's brain will process photons which physically strike his retinae, while he is physically standing on the embankment, to produce Albert's experiences.

dlouth15

Here's where I think the problem lies, Roosh. You believe that if the photons strike the retinas at different times, that the perception must be of non-simultaneous events.

This is not necessarily the case, however. In order to determine whether the central processing unit measures simultaneity we must model the physical setup.

The signals from each retina must travel to some other point to be processed and this can't happen instantaneously. Velocities v1 and v2 and distances d1 and d2 are involved.

But these are subject to the Lorentz transformation.

If there was instantaneous transmission of information to the central processing unit then there would be a problem. However this is not the case (and indeed would be breaking a physical law in its own right if it were so).

The apparent paradox is solved by assuming that normal physical processes are involved in perception and then applying the Lorentz transformation to these processes just like everything else.

In summary, Albert perceives simultaneous events regardless of the frame of reference. Light impinging on the retinas are two events in spacetime (which can appear simultaneous or not depending on the frame of reference) but the perception of simultaneity is a single event in spacetime. A single event is observed as a single event regardless of the frame of reference.

roosh

dlouth15 wrote: »

Here's where I think the problem lies, Roosh. You believe that if the photons strike the retinas at different times, that the perception must be of non-simultaneous events.

This is not necessarily the case, however. In order to determine whether the central processing unit measures simultaneity we must model the physical setup.

The signals from each retina must travel to some other point to be processed and this can't happen instantaneously. Velocities v1 and v2 and distances d1 and d2 are involved.

But these are subject to the Lorentz transformation.

If there was instantaneous transmission of information to the central processing unit then there would be a problem. However this is not the case (and indeed would be breaking a physical law in its own right if it were so).

The apparent paradox is solved by assuming that normal physical processes are involved in perception and then applying the Lorentz transformation to these processes just like everything else.

In summary, Albert perceives simultaneous events regardless of the frame of reference. Light impinging on the retinas are two events in spacetime (which can appear simultaneous or not depending on the frame of reference) but the perception of simultaneity is a single event in spacetime. A single event is observed as a single event regardless of the frame of reference.

The issue with applying the Lorentz transformation is that you, essentially, end up with what a relatively moving observer would, supposedly, measure of Albert's brain activity. That is, we end up with the relatively moving observers perspective. We're not interested in what a relatively moving observer would, supposedly, measure though. We are interested in how Albert's brain processes Albert's experiences.

Albert's brain processes photons which physically strike his retinae to produce Albert's experiences; as far as Albert's brain is concerned, when it is processing Albert's experiences, it doesn't apply the Lorentz transform to itself. It will, indiscriminately, process all photons, which physically strike Albert's retinae, in the order they are received, while he is standing on the embankment.

EDIT: as far as Albert's brian is concerned, the travel time for both signals is the same from both retinae.

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 they do physically strike his retinae in this order, then Albert's brain will process them as it does every photon which physically strikes his retinae.

dlouth15

roosh wrote: »

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 they do physically strike his retinae in this order, then Albert's brain will process them as it does every photon which physically strikes his retinae.

The way I think you need to look at things is in terms of a single spacetime. This is the physical reality where events occur. The various frames of reference are merely perspectives on this single spacetime.

Would you agree that from the point of view of observable events in spacetime, there is no problem; that even if, from a particular frame, the photons arrive non-simultaneously the signals will travel to the central processing unit and arrive in unison?

Would you agree that if we're dealing with a simple piece of machinery (the two light detectors, wires connected to a simple processor that flashes if the signals are received at the same time) that there is no issue and that a single flash happens regardless of the frame of reference?

roosh

dlouth15 wrote: »

The way I think you need to look at things is in terms of a single spacetime. This is the physical reality where events occur. The various frames of reference are merely perspectives on this single spacetime.

Would you agree that from the point of view of observable events in spacetime, there is no problem; that even if, from a particular frame, the photons arrive non-simultaneously the signals will travel to the central processing unit and arrive in unison?

Would you agree that if we're dealing with a simple piece of machinery (the two light detectors, wires connected to a simple processor that flashes if the signals are received at the same time) that there is no issue and that a single flash happens regardless of the frame of reference?

In effect we have been looking at it from a single spacetime; we've been looking at is as it is formulated in Einsteinian relativity; we've just been relating it back the physical, observational world.

Looking at it from a single spacetime, Albert's brain still processes photons which physically strike his retinae in the order they strike, while he is standing on the embankment. As far as his brain is concerned, it will still take the same amount of time for signals, from each retina, to arrive at the processing centre. S' will still say that the photons strike his retinae in the order of one first, then the other, while he is physically standing on the embankment.

But if you can propose how looking at it from a single spacetime will change any of the details, it's certainly something we would have to consider.

dlouth15

roosh wrote: »

In effect we have been looking at it from a single spacetime; we've been looking at is as it is formulated in Einsteinian relativity; we've just been relating it back the physical, observational world.

The problem is you are continually reverting to Albert's frame, i.e. the frame within which Albert is stationary.

Looking at it from a single spacetime, Albert's brain still processes photons which physically strike his retinae in the order they strike, while he is standing on the embankment. As far as his brain is concerned, it will still take the same amount of time for signals, from each retina, to arrive at the processing centre. S' will still say that the photons strike his retinae in the order of one first, then the other, while he is physically standing on the embankment.

Again this is a description from Albert's frame. The order in which the photons strike is an artifact of that particular frame of reference.

There's a conceptual problem I think you're having here. The cause of it I believe is that that some of the events under consideration are Albert's conscious perceptions. This forces the mind into privileging one frame of reference over another. We can't observe Albert's perceptions from another frame of reference. Only he can perceive them and he's stuck in his own frame of reference.

If we replace Albert with a simple physical system with photon detectors and a light that goes on, then this problem goes away. I think you need to examine why you are insisting on a conscious entity rather than a simple physical system.

But if you can propose how looking at it from a single spacetime will change any of the details, it's certainly something we would have to consider.

Because it forces you out of any particular frame. You mention in your post relating spacetime back to the physical observable world, but spacetime is the physical observable world. When you say "we've just been relating it back the physical, observational world.", what you mean is relating it to a particular frame of reference. It looks to me like whenever you talk about Albert's perceptions you are unwittingly reverting a frame of reference in which he is stationary.