Question on Lorentz transforms and relativity of simultaneity

roosh

I'm not entirely sure how to even phrase this question, but I'll try to make sense; maybe someone will understand what I'm trying to get at and can make sense of it.

Events
To get the co-ordinates for an event in a relatively moving reference frame we perform a Lorentz transform on the co-ordinates from the frame at which we are at rest, is that correct?

We, ourselves, could also be considered to be an event; that is, "me at a given time and place" could be represented by co-ordinates, just like any other event, is that also correct?

Simultaneous
Now, using the standard relativity example of the simultaneous lightning flashes in one reference frame being non-simultaneous in another, we can also include the "me at a given time and place event".

If the two lightning flashes are simultaneous in the frame in which I am at rest, then they are simultaneous with a specific "event of me", or are simultaneous with the "me at a given time and place" event.

When we subject the co-ordinates for the 3 events to a Lorentz transform, the "me at a given time and place" event - which must be the same event (just with different co-ordinates in the relatively moving frame) - will no longer be simultaneous with the lightning flashes.


Consequences
This is the bit I'm struggling with, I'm not entirely sure how to reason through the consequences; can this be taken as an indication that RoS must imply that "my past self" and/or "my future self" co-exists with "my present self"?

Morbert

roosh wrote: »

I'm not entirely sure how to even phrase this question, but I'll try to make sense; maybe someone will understand what I'm trying to get at and can make sense of it.

Events
To get the co-ordinates for an event in a relatively moving reference frame we perform a Lorentz transform on the co-ordinates from the frame at which we are at rest, is that correct?

We, ourselves, could also be considered to be an event; that is, "me at a given time and place" could be represented by co-ordinates, just like any other event, is that also correct?

Simultaneous
Now, using the standard relativity example of the simultaneous lightning flashes in one reference frame being non-simultaneous in another, we can also include the "me at a given time and place event".

If the two lightning flashes are simultaneous in the frame in which I am at rest, then they are simultaneous with a specific "event of me", or are simultaneous with the "me at a given time and place" event.

When we subject the co-ordinates for the 3 events to a Lorentz transform, the "me at a given time and place" event - which must be the same event (just with different co-ordinates in the relatively moving frame) - will no longer be simultaneous with the lightning flashes.


Consequences
This is the bit I'm struggling with, I'm not entirely sure how to reason through the consequences; can this be taken as an indication that RoS must imply that "my past self" and/or "my future self" co-exists with "my present self"?

If the lightning bolts are simultaneous in a given reference frame, it simply means the t coordinate is the same for both strikes.

roosh

Morbert wrote: »

If the lightning bolts are simultaneous in a given reference frame, it simply means the t coordinate is the same for both strikes.

I understand that, but what I'm trying to get at is somewhat different.

As you've mentioned in other discussions, we can be considered events; that is, we can give spacetime co-ordinates for ourselves just as we can for any other event.

Let's say that in the FoR in which I am at rest, two lightning strikes are simultaneous with the striking of midnight, which just happens to be the exact moment I turn 50. In my rest frame, the lightning strikes are simultaneous with me turning 50 - I'm sure in thought experiments like this we can make such assumptions about the aging process can we; it is essentially just a time co-ordinate, isn't it?


In a frame moving relative to me, at a given fraction of the speed of light, my turning 50 will not be simultaneous with both flashes of lightning; for arguments sake, one flash of lightning will happen when I'm still somwhere in the 49 age bracket, while the other will occur after I've turned 50 - as opposed to at the precise moment I turn 50.


I'm having difficulty reasoning what this means for the existence of "my past self", "my present self" and "my future self".

ceejay

In both frames of reference there is a progression from past self -> present self -> future self. The different frames of reference will just have different views of what is simultaneous to the various instants of self, if that makes sense

That's my understanding of it anyway!

roosh

ceejay wrote: »

In both frames of reference there is a progression from past self -> present self -> future self. The different frames of reference will just have different views of what is simultaneous to the various instants of self, if that makes sense

That's my understanding of it anyway!

The events of each reference frame are supposed to be equally valid, aren't they? So, the event that is 50yr old me, in the relatively moving reference frame, is supposedly equally as real as the me in the reference frame in which I am at rest; equally conscious, and equally capable of experience.

If 50yr old me, in my rest frame, observes the two lightning strikes as being simultaneous; but the equally valid 50yr old me, with co-ordinates from the relatively moving reference frame, doesn't witness the events as simultaneous, doesn't that have some serious implications for cause and effect; wouldn't 55yr old me have conflicting memories of those events?

citrus burst

roosh wrote: »

The events of each reference frame are supposed to be equally valid, aren't they? So, the event that is 50yr old me, in the relatively moving reference frame, is supposedly equally as real as the me in the reference frame in which I am at rest; equally conscious, and equally capable of experience.

If 50yr old me, in my rest frame, observes the two lightning strikes as being simultaneous; but the equally valid 50yr old me, with co-ordinates from the relatively moving reference frame, doesn't witness the events as simultaneous, doesn't that have some serious implications for cause and effect; wouldn't 55yr old me have conflicting memories of those events?

If 50 year old you is in both reference frames then maybe you have an argument. However 50 year old you is not in both reference frames so there isn't an problem. For reasoning see the post you made about twins and memory.

roosh

citrus burst wrote: »

If 50 year old you is in both reference frames then maybe you have an argument. However 50 year old you is not in both reference frames so there isn't an problem. For reasoning see the post you made about twins and memory.

In the reference frame in which I am at rest, the event that is me turning 50 is simultaneous with the two flashes of lightning; in the relatively moving reference frame, the event that is me turning 50 is not simultaneous with the lightning flashes. If the events in the relatively moving reference frame are as equally valid, and equally real, as those in the reference frame in which I am at rest, then I should remember the events as being both simultaneous and non-simultaneous.

Uless there is an inequality between reference frames, and the events in one aren't as valid as the events in another.

citrus burst

roosh wrote: »

In the reference frame in which I am at rest, the event that is me turning 50 is simultaneous with the two flashes of lightning; in the relatively moving reference frame, the event that is me turning 50 is not simultaneous with the lightning flashes. If the events in the relatively moving reference frame are as equally valid, and equally real, as those in the reference frame in which I am at rest, then I should remember the events as being both simultaneous and non-simultaneous.

Uless there is an inequality between reference frames, and the events in one aren't as valid as the events in another.

Yes, but like I said you are not in both reference frames. Roosh "sees" the lightning strikes being simultaneous in his reference frame R. Roosh' "sees" the lightning strikes as two distinct separate events in his reference frame R'.

Roosh'' can only have one set of memories of which they came from Roosh or Roosh' memories. So Roosh remembers much to his great satisfaction that as he turned 50, two towers outside were hit by lighning. OR Roosh remembers much to his great satisfaction that the last moment of his 49th year alive was heralded by a strike of lightning on one tower and the first moment of his 50th year was greeted by a lightning strike on a separate tower. Roosh does not remember both.

Roosh however has a friend, who happened to be travelling at a very high/low speed relative to Roosh and I stress very. At low speeds relative to each other they will agree. Roosh and his friend should never agree upon the timing of the lightning strike. Both are right.

This is an idea based off two very simple postulates, but leads to a very complicated, unintuitive and controversial theory known as "the Theory of Special Relativity."

1. All reference frames are equally valid
2. The speed of light is the same in all reference frames

Where do we get these postulates from? Well 1 comes from the fact that the universe should be the same every where. An experiment carried out on Mars is as equally valid as an experiment carried out anywhere else in the universe. How can you justify one set of observed data being "more right" then another set of data in a different reference frame? Assuming they were carried out the same.

This postulate has other repercussion's as well, seemingly ruling out the concept of absolute motion/rest, in doing so remaining self consistent.

2. At the time was a bit of a bold move made by Einstein, however, probably would have been figured out by the scientific community within a decade or so. Maxwell's equations to be consistent with experimental results seem to require a constant (or two). One particular constant when calculated out came to be about 3 x 10^8 in units of meters per second. This just so happened to be about the same as the speed of light.

This also has repercussion's assossiated with it as well. If one thing is to remain constant in all reference, then to be self consistent other things must change and as it happens length and time are just some of things that are not constant in all reference frames.

So with these two postulates, when you work out all the maths, paradoxes and make everything self consistent you end up with rather strange results, that would seem to go against all other experimental data. Data gathered over the course of the earths history. Bearing in mind that the max average speed a human ever moved up until about 50 years ago was +/- 30 x 10^0 m/s, a comparable 0.000000001% of the speed of light, it is no wonder that the predictions made by this theory are strange.

Even in itself this theory isn't the full picture. It only works in the special case of constant linear velocity. Any change in velocity and hence acceleration just simply are too advanced.

Any way, to try and answer your question about what consequences this has on your past, present, future self; not much is the short answer, taking into consideration that you can only be in one reference frame and hence only observe one of the given scenarios. Now if you had a friend in a different galaxy, you might get into a bit of an argument over when a star went supernova, however, armed with your Lorentz transforms you may come to some agreement.

You should look up "proper time" and "proper length." These may help you figure out what is going on

roosh

citrus burst wrote: »

Yes, but like I said you are not in both reference frames. Roosh "sees" the lightning strikes being simultaneous in his reference frame R. Roosh' "sees" the lightning strikes as two distinct separate events in his reference frame R'.

Roosh'' can only have one set of memories of which they came from Roosh or Roosh' memories. So Roosh remembers much to his great satisfaction that as he turned 50, two towers outside were hit by lighning. OR Roosh remembers much to his great satisfaction that the last moment of his 49th year alive was heralded by a strike of lightning on one tower and the first moment of his 50th year was greeted by a lightning strike on a separate tower. Roosh does not remember both.

Roosh however has a friend, who happened to be travelling at a very high/low speed relative to Roosh and I stress very. At low speeds relative to each other they will agree. Roosh and his friend should never agree upon the timing of the lightning strike. Both are right.

This is an idea based off two very simple postulates, but leads to a very complicated, unintuitive and controversial theory known as "the Theory of Special Relativity."

1. All reference frames are equally valid
2. The speed of light is the same in all reference frames

Where do we get these postulates from? Well 1 comes from the fact that the universe should be the same every where. An experiment carried out on Mars is as equally valid as an experiment carried out anywhere else in the universe. How can you justify one set of observed data being "more right" then another set of data in a different reference frame? Assuming they were carried out the same.

This postulate has other repercussion's as well, seemingly ruling out the concept of absolute motion/rest, in doing so remaining self consistent.

2. At the time was a bit of a bold move made by Einstein, however, probably would have been figured out by the scientific community within a decade or so. Maxwell's equations to be consistent with experimental results seem to require a constant (or two). One particular constant when calculated out came to be about 3 x 10^8 in units of meters per second. This just so happened to be about the same as the speed of light.

This also has repercussion's assossiated with it as well. If one thing is to remain constant in all reference, then to be self consistent other things must change and as it happens length and time are just some of things that are not constant in all reference frames.

So with these two postulates, when you work out all the maths, paradoxes and make everything self consistent you end up with rather strange results, that would seem to go against all other experimental data. Data gathered over the course of the earths history. Bearing in mind that the max average speed a human ever moved up until about 50 years ago was +/- 30 x 10^0 m/s, a comparable 0.000000001% of the speed of light, it is no wonder that the predictions made by this theory are strange.

Even in itself this theory isn't the full picture. It only works in the special case of constant linear velocity. Any change in velocity and hence acceleration just simply are too advanced.

Any way, to try and answer your question about what consequences this has on your past, present, future self; not much is the short answer, taking into consideration that you can only be in one reference frame and hence only observe one of the given scenarios. Now if you had a friend in a different galaxy, you might get into a bit of an argument over when a star went supernova, however, armed with your Lorentz transforms you may come to some agreement.

You should look up "proper time" and "proper length." These may help you figure out what is going on

Cheers citrus, I have become fairly familiar with the postulates of relativity, and how they lead to concepts, or conclusions such as relativity of simultaneity. It is the concept of RoS that this question is intended to look at, and the idea that all reference frames are equally valid; that is, the events in one reference frame are as equally valid as another.


I don't think your statement, that I am not in both reference frames, is entirely accurate; I think what is true is that I am not at rest in both reference frames. Insofar as I am an event which can be assigned spacetime co-ordinates in any reference frame, I am as much in any reference frame as the flashes of lightning; I might be moving through those reference frames, but I am certainly an event within those reference frames - although the idea of actually being in a mathematical reference frame is a separate philosophical discussion, insofar as Einsteinian relativity is concerned, I am an event in the relatively moving reference frame as much as the flashes of lightning are.


Equally valid
So, if we get back to the idea of reference frames being equally valid; in the relatively moving reference frame, 50yr old me is not simultaneous with the two lightning flashes; while 50yr old me is simultaneous with them, in my rest frame.

If the events of the relatively moving reference frame are equally valid, equally physical, and equally real*, then 50yr old me, which is moving through that reference frame should experience the flashes non-simultaneously, and thus should remember them as such. On the other hand, in my rest frame, 50yr old me sees the flashes simultaneously and thus remembers them accordingly.

Now, if the events in all reference frames are equally valid, equally physical, equally real, and are the same events, not different ones, then post 50yr old me should have conflicting memories of the events.

If post 50yr old me doesn't, it implies that there is an inequality between the reference frames, that the event that is 50yr old me is different across both reference frames; that somehow, the person the relatively moving observer sees is not me.





*where relativity of simultaneity isn't attributable to some form of optical illusion

citrus burst

roosh wrote: »

Cheers citrus, I have become fairly familiar with the postulates of relativity, and how they lead to concepts, or conclusions such as relativity of simultaneity. It is the concept of RoS that this question is intended to look at, and the idea that all reference frames are equally valid; that is, the events in one reference frame are as equally valid as another.

Well for one I do hope you agree that all reference frames are equal? You'd have an awful tough job explaining how they are not.

RoS exists even at Newtonian or Galilean relativity just in a different sense. You've probably been to a football game and seen someone kick a ball before you hear them? Or even thunder and lightning. These two events are analogous to the special relativistic case of observers disagreeing on the time of something. Albeit in a much more simple way.

roosh wrote: »

I don't think your statement, that I am not in both reference frames, is entirely accurate; I think what is true is that I am not at rest in both reference frames. Insofar as I am an event which can be assigned spacetime co-ordinates in any reference frame, I am as much in any reference frame as the flashes of lightning; I might be moving through those reference frames, but I am certainly an event within those reference frames - although the idea of actually being in a mathematical reference frame is a separate philosophical discussion, insofar as Einsteinian relativity is concerned, I am an event in the relatively moving reference frame as much as the flashes of lightning are.

Maybe I need to clarify more. You are only physically in one reference frame, unless there are two of you? You can only be on the train, or on the platform, or in your bed, or at your desk. You are correct in saying you are not at rest in all reference frames, but reference frames are only arbitrary. But you are at rest in the most important one (for you), your reference frame. Now you could go change your reference frame, ie by going for a jog or a drive, and still be at rest in that reference frame. What consequences do you think that will have?

roosh wrote: »

Equally valid
So, if we get back to the idea of reference frames being equally valid; in the relatively moving reference frame, 50yr old me is not simultaneous with the two lightning flashes; while 50yr old me is simultaneous with them, in my rest frame.

But like I said 50 year old you is not physically in the relatively moving reference frame and in the rest frame at the same time. It should be pointed out again that the choice of what is the moving frame and what is the rest is only arbitrary. So if your argument is based off the idea that one reference frame can be written in terms of another and as such causes the breakdown of relativity due to events not lining up as they should, then it doesn't really hold water.

roosh wrote: »

If the events of the relatively moving reference frame are equally valid, equally physical, and equally real*, then 50yr old me, which is moving through that reference frame should experience the flashes non-simultaneously, and thus should remember them as such. On the other hand, in my rest frame, 50yr old me sees the flashes simultaneously and thus remembers them accordingly.

So here, maybe you might not have noticed, but you have found a rather nice way of describing the same situation in two different ways, as far as I can tell. Ask yourself, before you even start thinking about relativity, whats the difference between the two sentences above? They both contain you, as a 50 year, moving relative to some other frame, so in other words two reference frames. Now like I said rest frames are arbitrary, so it doesn't matter if we use your rest frame or another one, its more a matter of convenience. In the first part you made yourself be the moving frame and in the second part you are the rest frame. So you are right in that the two reference frames should disagree on that timing of the event. However how can the same reference frame experience a difference?

roosh wrote: »

Now, if the events in all reference frames are equally valid, equally physical, equally real, and are the same events, not different ones, then post 50yr old me should have conflicting memories of the events.

Like I said, he can only ever be physically in one reference frame. He can be described by an infinite number, but eventually they will all coalesce into one frame. I mean a point in 3-D space can be described by any set of vectors (ax, by, cz). a,b,c are just arbitrary numbers that come from how the coordinate system was set up. x,y,z are just unit vectors pointing in a direction. You might call a point (3x, -8y, 70z) due to how you set up your coordinate system, I might call it (0x, 0y, 0z). Both point to the same point, both are equally valid, they just use different arbitrary coordinate systems.

You can very easily get between one system to another and it is similar for reference frames

roosh wrote: »

If post 50yr old me doesn't, it implies that there is an inequality between the reference frames, that the event that is 50yr old me is different across both reference frames; that somehow, the person the relatively moving observer sees is not me.

It is different across both reference frames. However 50 year old you only has one reference frame, described an infinite number of ways

roosh wrote: »

*where relativity of simultaneity isn't attributable to some form of optical illusion

This makes me laugh

roosh

citrus burst wrote: »

Well for one I do hope you agree that all reference frames are equal? You'd have an awful tough job explaining how they are not.

I would agree that they are all equal, in that they are all arbitrary, mathematical constructs which can be used to make predictions; I think there can be differences between the phyiscal objects which they describe, however.

citrus burst wrote: »

RoS exists even at Newtonian or Galilean relativity just in a different sense. You've probably been to a football game and seen someone kick a ball before you hear them? Or even thunder and lightning. These two events are analogous to the special relativistic case of observers disagreeing on the time of something. Albeit in a much more simple way.

This isn't quite the same issue

citrus burst wrote: »

Maybe I need to clarify more. You are only physically in one reference frame, unless there are two of you? You can only be on the train, or on the platform, or in your bed, or at your desk. You are correct in saying you are not at rest in all reference frames, but reference frames are only arbitrary. But you are at rest in the most important one (for you), your reference frame. Now you could go change your reference frame, ie by going for a jog or a drive, and still be at rest in that reference frame. What consequences do you think that will have?

A reference frame is an arbitrary, mathematical construct which is used to describe all physical objects and events; in that sense, all physical objects are in all reference frames, just with different co-ordinates.

To say that I can only be on the train is fine, if we are only discussing objects in the mathematical reference frame that describes the train; but we're discussing a mathematical reference frame which takes in the embankment and the train. In that reference frame both the train and the embankment are present, but in one mathematical representation the train is moving, while the embankement is labeled as "in motion" in the other. It is supposed to be the same, equally valid, equally physical train and embankment in both.

citrus burst wrote: »

But like I said 50 year old you is not physically in the relatively moving reference frame and in the rest frame at the same time. It should be pointed out again that the choice of what is the moving frame and what is the rest is only arbitrary. So if your argument is based off the idea that one reference frame can be written in terms of another and as such causes the breakdown of relativity due to events not lining up as they should, then it doesn't really hold water.

"50yr old me" isn't really present in any reference frame, because "50yr old me" is physical and a reference frame is a mathematical representation of the physical world, which includes all objects - or at least, all objects under consideration. In that sense, "50yr old me" is present in both reference frames, just with different co-ordinates, and labeled as moving in one but stationary in another. These reference frames are used to make predictions and deductions about the physical world.

When we take the co-ordinates of the simultaneous events, me and the lightning flashes, from my rest frame and do a Lorentz transform to get the co-ordinates of those events in the relatively moving refernce frame, we find that the events are no longer simultaneous. This means that "50yr old me" no longer observes simultaneous flashes of light.

Now, if the representation of the events in the relatively moving reference frame are the same, and as equally valid, as those represented by my rest frame; that is, if they represent the same phyiscal events and no one representation of them is more true than the other; then it means that "50yr old me" should have conflicting experiences of the lightning events; because the event that is "50yr old me" in the relatively moving reference frame is every bit as valid a the event that is "50yr old me" in the rest frame.

Alternatively, the events described in one reference frame do not correspond to the physical world, while the events described in the other do; meaning that one reference frame is more valid than the other.

citrus burst wrote: »

So here, maybe you might not have noticed, but you have found a rather nice way of describing the same situation in two different ways, as far as I can tell. Ask yourself, before you even start thinking about relativity, whats the difference between the two sentences above? They both contain you, as a 50 year, moving relative to some other frame, so in other words two reference frames. Now like I said rest frames are arbitrary, so it doesn't matter if we use your rest frame or another one, its more a matter of convenience. In the first part you made yourself be the moving frame and in the second part you are the rest frame. So you are right in that the two reference frames should disagree on that timing of the event. However how can the same reference frame experience a difference?

The issue is that, according to one reference frame, the event that is "50yr old me" is simultaneous with the two flashes of lightning, while in the other "50yr old me" isn't. If the events described by both reference frame are indeed the same events; if the events described by both reference frames both correspond equally to the physical world; if the events described by both reference frames are equally valid, then I should have conflicting experiences of those events; and not just those, but every event that has ever occurred, given the number of relatively moving reference frames that exist in the universe.

citrus burst wrote: »

Like I said, he can only ever be physically in one reference frame. He can be described by an infinite number, but eventually they will all coalesce into one frame. I mean a point in 3-D space can be described by any set of vectors (ax, by, cz). a,b,c are just arbitrary numbers that come from how the coordinate system was set up. x,y,z are just unit vectors pointing in a direction. You might call a point (3x, -8y, 70z) due to how you set up your coordinate system, I might call it (0x, 0y, 0z). Both point to the same point, both are equally valid, they just use different arbitrary coordinate systems.

As mentioned, we can't physically be in any reference frame, because reference frames are mathematical in nature; we can only exist in one location at a time, but a reference frame can take the entire universe into consideration, labeling some things as "in motion" and other as "at rest". I can only physically be in the train or on the embankment, but not both, but I can be represented by a mathematical reference frame that takes either as being the rest frame; that is, in am represented in both the reference frame that takes the emankment as the rest frame and the one that takes the train as the rest frame.

When we perform a Lorentz transform on the co-ordinates we find that "50yr old me" is simultaneous with the flashes of lightning in one reference frame, but not in the other.

If both are supposed to be equally valid representations of the physical world; if the events represented in one are as physical as those represented in the other; if one reference frame isn't a more true representation of the physical events than another, that is, if all reference frames are equally valid, then I should have conflicting experiences of those events.

You can very easily get between one system to another and it is similar for reference frames

citrus burst wrote: »

It is different across both reference frames. However 50 year old you only has one reference frame, described an infinite number of ways

This has, hopefully, been addressed above.

krd

roosh wrote: »

If 50yr old me, in my rest frame, observes the two lightning strikes as being simultaneous; but the equally valid 50yr old me, with co-ordinates from the relatively moving reference frame, doesn't witness the events as simultaneous, doesn't that have some serious implications for cause and effect; wouldn't 55yr old me have conflicting memories of those events?

You know I really hate some examples of relativity, because they really confuse people (like me)

But it's confusing anyway.

Simultaneity, as in witnessing a signal - an experiment you could do. Put two large speakers, 100m apart. Then from your stereo, which is connected to both speakers, you play a loud mono metronome, with the same signal going to each speaker. Let's call the speakers A and B.

If you start at A, speaker B, will sound out of sync, with A. Walk towards speaker B and they will gradually begin to sync, they will sync at 50m. Keep heading towards B, and they're out of sync. The simultaneity of events is relative to where you are, but causality is never effected. Doing this with light is different, but the bits that are the same are not the special bits that make special relativity special.

Now, that whole lightening strike thing, replace the lightening with photons. If you're moving, think what your movement would do to their wavelength relative to you. The speed of light is constant in all frames. If you're moving, one photon will have a shorter wavelength and the other a longer one relative to you. YOU MAY HAVE TO KEEP THINKING ABOUT THIS FOR A LONG TIME........if wavelength X frequency = the speed of light c.........And c is constant in all frames.....then the wavelength (space) can not be constant, and the frequency (time) can not be constant either.

If you're moving and it's lightening strikes, both will happen at different times, one will be brighter than the other. And both will have a slightly different colour.

But special relativity has no influence on cause and effect.


In general relativity, (which I don't know much about), you can theoretically go back in time by bending gravity, but there may be some kind of universe limit that stops this from being possible.

Morbert

roosh wrote: »

The events of each reference frame are supposed to be equally valid, aren't they? So, the event that is 50yr old me, in the relatively moving reference frame, is supposedly equally as real as the me in the reference frame in which I am at rest; equally conscious, and equally capable of experience.

If 50yr old me, in my rest frame, observes the two lightning strikes as being simultaneous; but the equally valid 50yr old me, with co-ordinates from the relatively moving reference frame, doesn't witness the events as simultaneous, doesn't that have some serious implications for cause and effect; wouldn't 55yr old me have conflicting memories of those events?

Try the transformations explicitly yourself. Let's say the rods a and b are each 1 lightsecond (ls) away from the observer in the middle. In the reference frame of the observer, we have:

Time of strikes is Ta =Tb = 0 s
Position of rod a is Xa = 1 ls
Position of rob b is Xb = -1 ls
Time strike a is witnessed is ta = 1 s
Time strike b is witnessed is tb = 1 s
The strikes are both witnessed at position x = 0 ls

Now let's transform the coordinates to a reference frame travelling at v relative to the observer. We'll use natural units, so that c = 1.

The time of strikes are

Ta' = γ(Ta-vXa) = -γv
Tb = γ(Tb-vXb) = γv

But the strikes are witnessed at

ta' = γ(ta-vx) = γ
tb' = γ(tb-vx) = γ

So you see that, even though the strikes are not simultaneous, all reference frames will agree that you witness both strikes simultaneously. Hence, causality is preserved.

roosh

Morbert wrote: »

Try the transformations explicitly yourself. Let's say the rods a and b are each 1 lightsecond (ls) away from the observer in the middle. In the reference frame of the observer, we have:

Time of strikes is Ta =Tb = 0 s
Position of rod a is Xa = 1 ls
Position of rob b is Xb = -1 ls
Time strike a is witnessed is ta = 1 s
Time strike b is witnessed is tb = 1 s
The strikes are both witnessed at position x = 0 ls

Now let's transform the coordinates to a reference frame travelling at v relative to the observer. We'll use natural units, so that c = 1.

The time of strikes are

Ta' = γ(Ta-vXa) = -γv
Tb = γ(Tb-vXb) = γv

But the strikes are witnessed at

ta' = γ(ta-vx) = γ
tb' = γ(tb-vx) = γ

So you see that, even though the strikes are not simultaneous, all reference frames will agree that you witness both strikes simultaneously. Hence, causality is preserved.

That's a neat little trick; but, by taking the time of one light-second, all you have succeded in demonstrating is that I am equidistant from the rods in each reference frame; that is, I am one light-second away from the rods in both reference frames; and the light will take one light-second to reach me from each rod. It says nothing about the simultaneity of receiving each flash. If it takes the light from rod A one light second to reach me, and it takes the light from rod B one light second to reach me, but the strike occurs at rod B before it occurs at rod A, the light from rod B will necessarily reach me first.

To put it in simpler terms; if I am equidistant from the rods in both frames, and light travels at the same finite speed in all directions; if the flash occurs at B before it occurs at A, then, by necessity, I must see the light from B before I see the light from A.

If I don't it implies that: a) I'm not equidistant from both rods, or b) light doesn't travel at the same finite speed in both directions.

citrus burst

roosh wrote: »

That's a neat little trick; but, by taking the time of one light-second, all you have succeded in demonstrating is that I am equidistant from the rods in each reference frame; that is, I am one light-second away from the rods in both reference frames; and the light will take one light-second to reach me from each rod. It says nothing about the simultaneity of receiving each flash.

I would like you to take at the line in Morbert's post
"Time of strikes is Ta =Tb = 0 s"
And perhaps rethink your argument

roosh

citrus burst wrote: »

I would like you to take at the line in Morbert's post
"Time of strikes is Ta =Tb = 0 s"
And perhaps rethink your argument

If I am equidistant from the rods where the lightning strikes, and at rest relative to them; and if the light travels at the same finite speed in all directions, and the light strikes one of the rods before the other; how is it possible that the light reaches me at the same time from both rods?

EDIT:By using one light second the ta' and tb' times only show that the rods are one light second away from me, and that the light takes one light second to travel from the rods to me; if the strikes occur at different times, then it necessarily follows that the light will reach me at different times.

citrus burst

roosh wrote: »

If I am equidistant from the rods where the lightning strikes, and at rest relative to them; and if the light travels at the same finite speed in all directions, and the light strikes one of the rods before the other; how is it possible that the light reaches me at the same time from both rods?

EDIT:By using one light second the ta' and tb' times only show that the rods are one light second away from me, and that the light takes one light second to travel from the rods to me; if the strikes occur at different times, then it necessarily follows that the light will reach me at different times.

Well the line "tA=tB=0 means that the strikes happened at the same time, arbitrarily chosen to be 0. You based an argument based on this not being the case.

roosh

krd wrote: »

You know I really hate some examples of relativity, because they really confuse people (like me).

But it's confusing anyway.

When we encounter something that conflicts with our existing beliefs, the result is confusion, as we try to make sense of the new information.

krd wrote: »

Simultaneity, as in witnessing a signal - an experiment you could do. Put two large speakers, 100m apart. Then from your stereo, which is connected to both speakers, you play a loud mono metronome, with the same signal going to each speaker. Let's call the speakers A and B.

If you start at A, speaker B, will sound out of sync, with A. Walk towards speaker B and they will gradually begin to sync, they will sync at 50m. Keep heading towards B, and they're out of sync. The simultaneity of events is relative to where you are, but causality is never effected. Doing this with light is different, but the bits that are the same are not the special bits that make special relativity special.

This example isn't representative of the issue, however; if the same person were experiencing hearing the speakers both in sync and out of sync, then it would represent the issue.

krd wrote: »

Now, that whole lightening strike thing, replace the lightening with photons. If you're moving, think what your movement would do to their wavelength relative to you. The speed of light is constant in all frames. If you're moving, one photon will have a shorter wavelength and the other a longer one relative to you. YOU MAY HAVE TO KEEP THINKING ABOUT THIS FOR A LONG TIME........if wavelength X frequency = the speed of light c.........And c is constant in all frames.....then the wavelength (space) can not be constant, and the frequency (time) can not be constant either.

If you're moving and it's lightening strikes, both will happen at different times, one will be brighter than the other. And both will have a slightly different colour.

But special relativity has no influence on cause and effect.

In both reference frames I am at rest relative to the poles, where the lightning strikes; the difference is that, in one, the strikes are simultaneous with "50yr old me", in the other they aren't; this means that "50yr old me" should have discordant experiences of the lightning events.

We can try to crystalise the issue a little further by adding another event; let's say that the observer moving relative to me fires a gun at me, such that it wounds my arm; let's say that the event of the bullet hitting my arm is simultaneous (in the relatively moving reference frame) with the event of the light from rod B reaching my retina. In this case the wounding of my arm will be simultaneous with only one flash of light, while both flashes are simultaneous in my rest frame. This will make for an unmistakeably discordant experience of the same events.

roosh

citrus burst wrote: »

Well the line "tA=tB=0 means that the strikes happened at the same time, arbitrarily chosen to be 0. You based an argument based on this not being the case.

tA=tB=0 demonstrates that the flashes are simultaneous in the rest frame, it says nothing about the relatively moving frame. When we take one light second as the measure of the distance of the rods, and the time of the light hitting my retina, then all that has been demonstrated by the Lorentz transform is that the rods are equidistant from me in both frames, and that light takes one second to reach me from each rod; it says nothing of the strikes being non-simultaneous in the relatively moving thread.

But I am also basing my argument on a more basic, and more obvious fact, that doesn't really allow for mathematical tricks; if I am equidistant from the rods, and light travels at the same finite speed in all directions, and if the light hits one rod before it hits another, how is it possible for the light from both rods to reach me simultaneously?

citrus burst

roosh wrote: »

tA=tB=0 demonstrates that the flashes are simultaneous in the rest frame, it says nothing about the relatively moving frame.

Yup

roosh wrote: »

When we take one light second as the measure of the distance of the rods, and the time of the light hitting my retina,

Yup, Morbert's post said that

roosh wrote: »

then all that has been demonstrated by the Lorentz transform

Nothing so far has been transformed. We still only have one frame.

roosh wrote: »

is that the rods are equidistant from me in both frames,

Still only one frame

roosh wrote: »

and that light takes one second to reach me from each rod;

Yup

roosh wrote: »

it says nothing of the strikes being non-simultaneous in the relatively moving thread.

Yup it only talks about one frame

roosh wrote: »

But I am also basing my argument on a more basic,

I'd love to hear it. In your own words, pictures and all

roosh wrote: »

and more obvious fact,

Apparently not, what is it?

roosh wrote: »

that doesn't really allow for mathematical tricks;

What tricks? What don't you like about maths? You want to see mathematically trickery, you should study electrodynamics or quantum mechanics. In comparison to some of the trickery you need there, special relativity is just basic geometry algebra.

roosh wrote: »

if I am equidistant from the rods, and light travels at the same finite speed in all directions, and if the light hits one rod before it hits another, how is it possible for the light from both rods to reach me simultaneously?

Because you wear a monocle, which slows the light from one rod down just enough to let the light from the other to catch up.
Joking aside, it isn't possible if you aren't moving relative to the rods.

krd

roosh wrote: »

If I am equidistant from the rods where the lightning strikes, and at rest relative to them; and if the light travels at the same finite speed in all directions, and the light strikes one of the rods before the other; how is it possible that the light reaches me at the same time from both rods?

Your statement doesn't make sense. If you're at rest relative to the two rods, and equidistant, then when you witness the strike, both strike will be simultaneous to your frame of reference.

And if your claiming the frame as a rest frame (you, the two sources are at rest relative to each other, you will not witness any special relativity effect)

If all bodies are at rest, relative to each other, then Euclidean geometry holds within the frame. There is no distortion in space or time, as long as none of the bodies start to move relative to each other.

roosh

citrus burst wrote: »

Yup

Yup, Morbert's post said that

Nothing so far has been transformed. We still only have one frame.

Still only one frame

Yup


Yup it only talks about one frame

I'd love to hear it. In your own words, pictures and all

Apparently not, what is it?

What tricks? What don't you like about maths? You want to see mathematically trickery, you should study electrodynamics or quantum mechanics. In comparison to some of the trickery you need there, special relativity is just basic geometry algebra.

Because you wear a monocle, which slows the light from one rod down just enough to let the light from the other to catch up.
Joking aside, it isn't possible if you aren't moving relative to the rods.

You may have already been replying when I added the edit to one of the posts above, but I'll re-post it here again:

EDIT:By using one light second the ta' and tb' times only show that the rods are one light second away from me, and that the light takes one light second to travel from the rods to me; if the strikes occur at different times, then it necessarily follows that the light will reach me at different times.

krd

roosh wrote: »

We can try to crystalise the issue a little further by adding another event; let's say that the observer moving relative to me fires a gun at me, such that it wounds my arm; let's say that the event of the bullet hitting my arm is simultaneous (in the relatively moving reference frame) with the event of the light from rod B reaching my retina. In this case the wounding of my arm will be simultaneous with only one flash of light, while both flashes are simultaneous in my rest frame. This will make for an unmistakeably discordant experience of the same events.

There is a distance between your arm and eye......

The "observer" in Euclidean space, is a single point. Not every point in the "frame" of reference. The "frame" never really exists. An observer who sees a bullet hit your left arm, and a light flash hit your left eye simultaneously, will see a light flash hit your right eye later, then the left eye. If you are in a point frame, equidistant to both eyes, you'll see the light flash hit both eyes simultaneously. But the bullet will hit the arm later. These are not good examples.

And even if, Mr. Roosh, the light struck both eyes simultaneously as a bullet striking your arm, it would take at least a 100 milliseconds for you to register being shot in the arm. And you would say "but the bullet hitting my arm, and the length of time it takes the signal from the nerves to reach my brain has nothing to do with relativity"....but Oh yes it does.

roosh

krd wrote: »

Your statement doesn't make sense. If you're at rest relative to the two rods, and equidistant, then when you witness the strike, both strike will be simultaneous to your frame of reference.

And if your claiming the frame as a rest frame (you, the two sources are at rest relative to each other, you will not witness any special relativity effect)

If all bodies are at rest, relative to each other, then Euclidean geometry holds within the frame. There is no distortion in space or time, as long as none of the bodies start to move relative to each other.

If both reference frames, S and S' are equally valid, and the events they describe are equally physical, equally real, and equally representative of the physical world they attempt to describe, then we can deduce that I should have discordant experiences of the events.

In S, the lightning strikes simultaneously, and given that I am equidistant from the rods, and that light travels at the same speed in all directions, I observe the flashes simultaneously; that is "50yr old me" observes the flashes simultaneously.

When we transform the co-ordinates for these events into S', we find that "50yr old me" no longer observes the flashes simultaneosly; because, according to S', I am equidistant from the rods, light travels at the same speed in both directions, but, the flashes occur non-simultaneously, so the light reaches me non-simultaneously in S'.

If S' is as valid as S, then I should have discordant experiences of the lightning events.

roosh

krd wrote: »

There is a distance between your arm and eye......

The "observer" in Euclidean space, is a single point. Not every point in the "frame" of reference. The "frame" never really exists. An observer who sees a bullet hit your left arm, and a light flash hit your left eye simultaneously, will see a light flash hit your right eye later, then the left eye. If you are in a point frame, equidistant to both eyes, you'll see the light flash hit both eyes simultaneously. But the bullet will hit the arm later. These are not good examples.

And even if, Mr. Roosh, the light struck both eyes simultaneously as a bullet striking your arm, it would take at least a 100 milliseconds for you to register being shot in the arm. And you would say "but the bullet hitting my arm, and the length of time it takes the signal from the nerves to reach my brain has nothing to do with relativity"....but Oh yes it does.

We can have the bullet hit my retina, and make the event simultaneous with the light hitting my retina; or slightly before, or slightly after; it doesn't have to be a bullet either, just something that impairs my vision; bird droppings on my glasses, or whatever. We can increase the distances between the rods too, to allow for the effect to be more noticeable.

krd

roosh wrote: »

This example isn't representative of the issue, however; if the same person were experiencing hearing the speakers both in sync and out of sync, then it would represent the issue.

It is possible for person to hear the speakers in sync with one ear, and out of sync with the other ear.

But if you take it to a finer level, your hearing can pick up on tiny differences and locate the direction a sound is coming from.

krd

roosh wrote: »

We can have the bullet hit my retina, and make the event simultaneous with the light hitting my retina; or slightly before, or slightly after; it doesn't have to be a bullet either, just something that impairs my vision; bird droppings on my glasses, or whatever. We can increase the distances between the rods too, to allow for the effect to be more noticeable.

In reality, neither of your eyes ever experience events as simultaneous. Your brain doesn't notice. In fact your brain takes two images where there is a difference due to parallax and merges them into a single coherent image, with a sense of depth. Which is an illusion created by the brain.

Our whole sense of simultaneity is an illusion. It can take 140 milliseconds for the signal you've stubbed you toe to reach your brain - even if you've witnessed it, it seems simultaneous, but this is just your brain giving you an illusion that the events were simultaneous.

roosh

krd wrote: »

In reality, neither of your eyes ever experience events as simultaneous. Your brain doesn't notice. In fact your brain takes two images where there is a difference due to parallax and merges them into a single coherent image, with a sense of depth. Which is an illusion created by the brain.

Our whole sense of simultaneity is an illusion. It can take 140 milliseconds for the signal you've stubbed you toe to reach your brain - even if you've witnessed it, it seems simultaneous, but this is just your brain giving you an illusion that the events were simultaneous.

This is fair enough, but in terms of causality, the simultaneous arrival of light at my eyes would have a different effect than light arriving non-simultaneously.

This means there is an apparent inconsistency in the theory.

Morbert

roosh wrote: »

That's a neat little trick; but, by taking the time of one light-second, all you have succeded in demonstrating is that I am equidistant from the rods in each reference frame; that is, I am one light-second away from the rods in both reference frames; and the light will take one light-second to reach me from each rod. It says nothing about the simultaneity of receiving each flash. If it takes the light from rod A one light second to reach me, and it takes the light from rod B one light second to reach me, but the strike occurs at rod B before it occurs at rod A, the light from rod B will necessarily reach me first.

To put it in simpler terms; if I am equidistant from the rods in both frames, and light travels at the same finite speed in all directions; if the flash occurs at B before it occurs at A, then, by necessity, I must see the light from B before I see the light from A.

If I don't it implies that: a) I'm not equidistant from both rods, or b) light doesn't travel at the same finite speed in both directions.

No offence roosh, but it is clear that you are not thinking things through. This is not a neat little trick. This is the explicit transformation that you should be studying. You should, for example, have remembered that since this transformation preserves the speed of light in all reference frames, the centre of the expanding spheres of light from the flash will remain stationary in all reference frames. In the reference frame where you are moving, you will be moving towards one sphere of light and away from the other, but since the two strikes occur at different times in that frame, both spheres meet you at the same time.

ceejay

roosh wrote: »

When we take the co-ordinates of the simultaneous events, me and the lightning flashes, from my rest frame and do a Lorentz transform to get the co-ordinates of those events in the relatively moving refernce frame, we find that the events are no longer simultaneous. This means that "50yr old me" no longer observes simultaneous flashes of light.

Now, if the representation of the events in the relatively moving reference frame are the same, and as equally valid, as those represented by my rest frame; that is, if they represent the same phyiscal events and no one representation of them is more true than the other; then it means that "50yr old me" should have conflicting experiences of the lightning events; because the event that is "50yr old me" in the relatively moving reference frame is every bit as valid a the event that is "50yr old me" in the rest frame.

I think these two paragraphs, and especially the last sentence, highlight an assumption which is where I think you're going wrong. Essentially the moving observer is not you, it is something else which is moving relative to you and has a moving frame of reference relative to you in your rest frame of reference, and it is observing three events: the lightning strikes and you turning 50. So to that observer the three events are not simultaneous, but to you they are.

You cannot be both the observer at rest and the observer moving relative to yourself at the same time!

You see the flashes simultaneously with turning 50 because you are at rest, and someone else moving relative to you would describe the situation differently due to relativity. You cannot be both at rest and moving at the same time, so you cannot experience both descriptions of the events at the same time, and hence there is no way for you to remember both descriptions as you seem to be asserting.

A way of thinking about it which may help clarify it is this:

You are with a friend Alex who is standing still right beside you when you turn 50. At the same time your other friend Brian is speeding past at a significant fraction of the speed of light. You see the two flashes of lightning striking just as you turn 50, and you say "wow did you see that, those flashes of lightning happened just as I turned 50!"

Alex would agree with you and says "yes, amazing!" (if we ignore the very slight difference in when he would perceive the light flashes due to the slight difference in position of him versus you - it would be extremely small and probably not humanly discernible anyway).

Later you talk to Brian after he has finished speeding around the place, and he disagrees with the description that you and Alex agree on, saying that he saw one flash, then you turning 50, and then the second flash. Here I'm assuming there's some external visible manifestation of you turning 50 that Brian can detect - maybe all your hair turned grey at that moment!

Neither you, Alex, or Brian have any set of superimposed memories of both descriptions, since you each experienced the events according to your own frames of reference. However using the Lorenz transformations and Brian's information of the speed he was travelling at relative to you and Alex, you can work out that the two descriptions are actually consistent.

You and Alex would be able to visualise what it must have looked like for Brian, including accurately determining the time between the three events as he perceived them, and Brian would be able to visualise that the events would have appeared as simultaneous for you and Alex.

That last bit is important, and as has been shown in other posts: Brian wouldn't see the events as simultaneous, but he can work out that you would have seen them as simultaneous in your frame of reference. This means that while the first part of your assertion is correct,

roosh wrote: »

When we take the co-ordinates of the simultaneous events, me and the lightning flashes, from my rest frame and do a Lorentz transform to get the co-ordinates of those events in the relatively moving refernce frame, we find that the events are no longer simultaneous.

(which is true from the perspective of an observer in the moving frame of reference), your next part is incorrect

roosh wrote: »

This means that "50yr old me" no longer observes simultaneous flashes of light.

since the moving observer can do the transformation in reverse to determine that "50 yr old you" would have seen them as simultaneous.

All the events, objects, individuals, etc. in the scenario are real and happen. However observers moving at significant speeds relative to each other will have different descriptions of when exactly the events occur. No observer can directly experience the sequence events of another observer moving relative to them, but they can work out using the Lorenz transformations what it would be like for them.

Does any of that help?

roosh

Morbert wrote: »

No offence roosh, but it is clear that you are not thinking things through. This is not a neat little trick. This is the explicit transformation that you should be studying. You should, for example, have remembered that since this transformation preserves the speed of light in all reference frames, the centre of the expanding spheres of light from the flash will remain stationary in all reference frames. In the reference frame where you are moving, you will be moving towards one sphere of light and away from the other, but since the two strikes occur at different times in that frame, both spheres meet you at the same time.

Hey, no offence taken; it's all in the way of a good natured debate.

I think the above, though, just highlights an inconsistency in the theory; or an unfortunate consequence perhaps; that of giving consciousness a seemingly causal effect on the behaviour of light.

Two more events
We can amend the thought experiment slightly, by introducing two more events, which should hopefully help demonstrate the issue further. If we add two light detectors and position them so that they are just in front of the observer at rest in S. We can actually give the observer special headgear that has the detectors attached, such that the detectors are located just in front of each retina. The detectors can be located at a point on the expanding sphere of light that makes them symmetrical with the retinae of the observer; this will ensure the simultaneity of the events.

So, the flashes occur simultaneously in S; the light travels towards the observer located midway between A and B; the light hits each detector simultaneously and results in two more events.

Relatively moving
There is a relatively moving observer, at rest in S'; performing a lorentz transform we find that the flahses do not occur simultaneously in S', and neither do the events where the light hits the photo receptors.

So, if we conclude that the light receptor events are non-simultaneous, but conclude that the light reaches the observer simultaneously, there must be something about the consciousness of the observer that causes the difference.

The non-simultaneity of the ligth receptor events may be miniscule, but it is sufficient to be an issue.


Laser eye surgery
We may be able to formulate the thought experiment in such a way that it demonstrates the issue better.

Again, we can use the bones of the traditional thought experiment, but just alter it slightly; let's say there is an observer located midway between two rods, A and B; atop the rods are two lasers which will blind the observer if it comes into contact with his eye; the observer is positioned in such a way that his left retina is the same distance from the laser at A, as his right retina is from the laser at B.

In frame S, the lasers on A and B fire simultaneously; the lasers hit each retina simultaneously and can be considered two separate events; the observer is blinded in both eyes simultaneously.


There is a relatively moving observer, who is at rest in S'; performing the Lorentz transform we find that the lasers fire non-simultaneously in S'; we also find that the other two events, of the laser hitting each retina of the observer, occurs non-simultaneously; blinding him in one eye, before the other.


Thus, if both S and S' are equally valid, or accurate, representations of the physical world, the observer should have discordant experiences.