Exploring the Paradox of Relative Truth in Special Relativity

[name123]

I'm a little confused about the sausage versus pastry thing, but in terms of two accelerating rockets, there are two different frames to consider: (1) the frame of someone on board the rocket (the rocket frame), (2) the frame of someone who is not accelerating (the inertial frame)

If the distance between rockets is constant as measured in the rocket frame, then

1. The acceleration felt by the rear rocket will be greater than that of the front rocket
2. The distance between rockets is shrinking as measured in the inertial frame

If the distance between rockets is constant as measured in the inertial frame, then

1. The acceleration felt by the two rockets is the same
2. The distance between rockets is growing as measured in the rocket frame.

Well from what I quoted from Janus in post #68 I assume Janus was considering it to be the first case. But what case do you think it will be for the following scenario.

There are two spaceships (the "sausage" segments) inside a large tubular spaceship (the "pastry"). They are separated by a distance of 10 light years. All the clocks are synchronised. The two spaceships then at the same point in time (from the "pastry" frame of reference) accelerate to 0.6c.

 

[name123]

You are assuming a step, resynchronization of Pastry's clocks, that doesn't happen.

I wasn't assuming a re-synchronisation, it was that you had written:

However if the crew in the front and in the back of Sausage compared their wristwatches, they could be hours off.

You wrote:

Each Pastry crewman would see, using his wristwatch, that the acceleration started at 0.00s, and ended at say 0.001s. Then they started to decelerate at 0.800s and finished at 0.801s. Again, each crewman would see the same.
But if, during the way (the 0.8s they are moving), they looked around, they would "see" (rather "compute" or "estimate") the wristwatches toward the front showing some time in the past, and the wristwatches behind as some time in the future.

Originally the "pastry" ship was at rest, but I see you have changed them around. So you are saying that the accelerating ship would "compute" the wristwatches at the front showing some time in the past. But they would be wrong, as the clocks at the front would have measured the acceleration to have stopped at the same time, and the journey at 0.6c to have been for the same amount of time. Events would be measured as occurring at the same time.

If everyone resynchronized their wristwatches when they started to move, they would need to agree on a master clock, say the central one. So the crewman in the middle would keep the wristwatch at 0.001s, but those in front would move it from 0.001s to say -750 and those in the back to say +750.
(If the trip never stopped, they could now walk around, comparing wristwatches, and they would agree that indeed all their clocks show the same time.)
Then the trip would stop at 0.8s central clock, -749.2 front clock, 750.8 rear clock. Again, after stopping, they would realize that the clocks are not synchronized any more, and would need to adjust them again.

You seem to be saying that if they synchronised their clocks, then in their inertial frame (when it is cruising at 0.6c) events would be measured as taking place at different times (such as the time each segment started to decelerate). And strangely, those at the front would seem to be stating that the re-synchronisation happened for them say 750 seconds before it did for the clock in the middle. And that the 0.8 second trip ended for them roughly 741.2 seconds before it started for the middle clock, even though they agree that they had all set off at the same time.

Without the resynchronization,
Front Pastry clock: 0.800s
Sausage clock nearest to Pastry's front: 1.000s
Back Pastry clock: 0.800s
Sausage clock nearest to Pastry's end: 1.000s
Note: Pastry is the accelerating/decelerating one.

And presumably here, when the ship decelerates a difference in clock times would be measured. The clocks on the ship that did the accelerating having ticked less. The longer it had traveled for the greater the difference between the clocks.

I find this slightly confusing also, and I'll explain why. Supposing there were 7 ships, A, B, C, D, E, F, G. They are all at rest with each other. And they are all tubular. B fitting in A, C fitting in B, D fitting in C and so on. And all several hundred light years long.

A remains at rest and B accelerates to 0.1c, Presumably B's clock would have ticked less than A's if after its journey it returned to A's rest frame.
C accelerates to 0.2c. Presumably C's clock would have ticked less than B's if they both stopped (with respect to A).
and so on until F and G which both accelerate to 0.6c. Presumably both would have ticked less than the A, B, C, D and E ships if they all came to rest with A.

But now imagine F and G were in fact the "pastry" and "sausage" ship we were referring to. So when G accelerates to be at rest with A, wouldn't it actually be F's clock that is ticking slower than G's. Such that if G stayed at rest with A for a few years, and the accelerated to be at rest with F, F's clock would show the lower amount of time passing, not the other way around?

Thanks for your patience by the way. As you can see I am still finding what are presumably basic things still quite confusing.

 

[SlowThinker]

Well from what I quoted from Janus in post #68 I assume Janus was considering it to be the first case.

If they accelerate simultaneously by the same amount, it must be scenario 2.

But what case do you think it will be for the following scenario.

You are introducing 3rd or so scenario in the same thread. It won't help you at all. Understand one and move to the next.

In particular, it seems you still haven't quite understood what happens when a short train starts moving along a track that has a clock mounted every meter. While you answered the questions correctly, you aren't applying that in other places.

Also I think the Pastry used to be the accelerating ship.

 

[name123]

If they accelerate simultaneously by the same amount, it must be scenario 2.

So when Janus wrote:

This is a lot more complicated than it seems. If you arranged things so that in the sausage frame, the spacing between segments remained constant and all the segments started and stopped accelerating at the same moment, then according to the pastry ship, the segments and thus the distance between them was shrinking due to length contraction during this whole acceleration. But this also means that, at any given moment the Leading segment was traveling at a lower speed relative to the rear segment and thus its clock was exhibiting a greater time dilation rate. In other words, according to the pastry ship, the clocks in the segments wouldn't be ticking at the same rate.

I presume he had changed the scenario which caused me some confusion.

You are introducing 3rd or so scenario in the same thread. It won't help you at all. Understand one and move to the next.

In particular, it seems you still haven't quite understood what happens when a short train starts moving along a track that has a clock mounted every meter. While you answered the questions correctly, you aren't applying that in other places.

Also I think the Pastry used to be the accelerating ship.

The scenario is pretty similar to the one in post #34 accept that the clocks start in synch and one ship undergoes acceleration. In post #34 the pastry ship was the one that was being considered to be analogous to the track, though then given the symmetry in the space it allowed it to be relative which one was considered moving. But in post #47 for example where there is acceleration, it seems as though the sausage ship was being considered to be the one accelerating. But it may have changed throughout the conversation.
.

 

[ZapperZ]

I don’t recognize “relative truth” as a standard term in SR. Do you mean “reference frame”?

Your scenario is simply a bunch of twin paradoxes in parallel. The resolution is exactly the same:

http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_paradox.html

This is definitely late, but I agree with this. In light of Giuliani's idiotic "Truth isn't truth" comment, maybe this thread should be re-titled with something more appropriate, especially considering that "relative truth" is never popularly used in Relativity.

Zz.

 

[SlowThinker]

Originally the "pastry" ship was at rest, but I see you have changed them around.

Sorry, the thread is running for too long and on iPad it's sometimes not possible to review older posts while typing.

So you are saying that the accelerating ship would "compute" the wristwatches at the front showing some time in the past. But they would be wrong

The resynchronized timing would not be wrong. If they didn't do it, and the crewmen from the head of the ship went to meet those at the tail, they would notice that their wristwatches are off.
It's simply a different reference frame. If the clocks are showing the same time in one, they won't be in the other.

You seem to be saying that if they synchronised their clocks, then in their inertial frame (when it is cruising at 0.6c) events would be measured as taking place at different times (such as the time each segment started to decelerate). And strangely, those at the front would seem to be stating that the re-synchronisation happened for them say 750 seconds before it did for the clock in the middle. And that the 0.8 second trip ended for them roughly 741.2 seconds before it started for the middle clock, even though they agree that they had all set off at the same time.

No. They started at the same time in the, uh, Pastry time. But let's have crewman Head who does this:
clock shows 0; I set the clock to 750; wait for 0.8s; what's the time now?
Crewman Tail does this:
clock shows 0; I set the clock to -750; wait for 0.8s; what's the time now?
In their life, they might say that it all took 0.8s, but really, they stopped at different times because their clocks were showing different numbers.

I find this slightly confusing also, and I'll explain why.
...
wouldn't it actually be F's clock that is ticking slower than G's. Such that if G stayed at rest with A for a few years, and the accelerated to be at rest with F, F's clock would show the lower amount of time passing, not the other way around?

There is really no "slower" clock, in particular each of them is slower than the other. Distance is important. Sausage moves to meet new Pastry's clock, that, despite running slower, are already showing higher time.
What I said about Sausage and Pastry clocks doesn't change if there is ship A flying around. But A's crew might say that neither Sausage nor Pastry clocks are properly synchronized.

If you want to define a new scenario with ships A, Sausage and Pastry, you need to specify how they synchronize the clocks along each ship, in which frame the acceleration appears to be simultaneous, and other things.
If Sausage starts to move, Pastry waits a second, then accelerates to match Sausage, it's the same scenario as with Sausage slowing down instead.

 

[Sorcerer]

This is definitely late, but I agree with this. In light of Giuliani's idiotic "Truth isn't truth" comment, maybe this thread should be re-titled with something more appropriate, especially considering that "relative truth" is never popularly used in Relativity.

Zz.

According to the link below, Einstein wanted it to be called the theory of invariance.

http://www.f.waseda.jp/sidoli/MI404_23_Einstein.pdf

 

[name123]

No. They started at the same time in the, uh, Pastry time. But let's have crewman Head who does this:
clock shows 0; I set the clock to 750; wait for 0.8s; what's the time now?
Crewman Tail does this:
clock shows 0; I set the clock to -750; wait for 0.8s; what's the time now?
In their life, they might say that it all took 0.8s, but really, they stopped at different times because their clocks were showing different numbers.

I accept that it is "pastry time" that they all started off together. But when crewman Head's clock is set to -750, is not crewman Head of the opinion that the middle clock will not show 0.8 seconds until 750.8 seconds have passed, because when it does it will do so simultaneously to crewman Head's clock showing 0.8 seconds? What I am also not clear on is what crewman Head would be thinking the middle clock was showing simultaneous to it's clock showing -750.

Edit: Sorry for being so slow here, I assume the answer is that the paradox of crewman Head claiming that it is true that crewman Head and crewman Middle accelerated at the same time, and claiming that it is true that both it and crewman Middle decelerated 0.8s after each of them accelerated, while also claiming that it is true that crewman Middle won't decelerate until 750 seconds after crewman Head did comes about because the statements involve different frames of reference, and that the truth is relative to the frame of reference (in the special relativity interpretation of the Lorentz transformations).

If you want to define a new scenario with ships A, Sausage and Pastry, you need to specify how they synchronize the clocks along each ship, in which frame the acceleration appears to be simultaneous, and other things.
If Sausage starts to move, Pastry waits a second, then accelerates to match Sausage, it's the same scenario as with Sausage slowing down instead.

If they synchronise the clocks in the frame of rest frame A. Then presumably G and F's clocks will appear to tick 0.8s for each tick of 1s in rest frame A at the point they are both cruising at 0.6c. And when G comes to rest with A then presumably it is back to a 1:1 tick with A. And so F's clock will tick 0.8s for each 1s tick of G's.

But is it that G and F are cruising at 0.6c and they then both synchronise their clocks, and then G comes to rest with A, that G's clock will tick 0.8s for each 1s tick of F's?

If so then I do find it strange that adjusting the time of F for example in the synchronisation event would alter the relative tick rate.

Edit 2: As a side note, presumably if what I experience corresponds to my neural state, then what my neural state was at a given point in time would vary depending on the frame of reference of the observer. What neural events were simultaneous would vary. Would the variations in simultaneity not imply variations of experience?

 

[SlowThinker]

because the statements involve different frames of reference

Yes, start and end is in Pastry frame while the cruise is in Sausage frame. Either the clocks are left running, in which case they are, in a sense, showing meaningless value during the cruise. Or you can resync them, but in this new clock scheme the trip starts at different times for different crewmen.

But is it that G and F are cruising at 0.6c and they then both synchronise their clocks, and then G comes to rest with A, that G's clock will tick 0.8s for each 1s tick of F's?

As seen from F, yes. As seen from A or G, it would be the F clock running slower.

If so then I do find it strange that adjusting the time of F for example in the synchronisation event would alter the relative tick rate.

Right, it doesn't. It's the motion of the observer that changes the numbers. Your own time is always the fastest.

 

[name123]

Right, it doesn't. It's the motion of the observer that changes the numbers. Your own time is always the fastest.

Ok but earlier you wrote:

The Sausage crew would see the newly nearest Pastry clock as all showing 1.00s. Their own wristwatch would show 0.80s.

Which seems to be suggesting that the sausage crew would have seen their own time as slower.

Also I previously added an edit which would have been after you started responding:

As a side note, presumably if what I experience corresponds to my neural state, then what my neural state was at a given point in time would vary depending on the frame of reference of the observer. What neural events were simultaneous would vary. Would the variations in simultaneity not imply variations of experience?

The point being would there be disputes about what you were experiencing given the interpretation, but an absolute truth with regards to the evidence as to what you were experiencing?

 

[SlowThinker]

Ok but earlier you wrote:

The Sausage crew would see the newly nearest Pastry clock as all showing 1.00s. Their own wristwatch would show 0.80s

Which seems to be suggesting that the sausage crew would have seen their own time as slower.

Just before deceleration, the Pastry clock nearest at the time of start, now 0.6*0.8=0.48 light seconds away, would indeed be showing only 0.8*0.8=0.64s. But the new clock, that jumped ahead to 0.36 when the Sausage suddenly accelerated, despite running slower, still show 1.00s when they arrive nearby.
(I'm not sure if I made a mistake in the numbers but it seems reasonable).

The point being would there be disputes about what you were experiencing given the interpretation, but an absolute truth with regards to the evidence as to what you were experiencing?

I'm not sure what you're talking about. The theory of relativity describes the one objective truth (as far as we can tell). It is very logical and consistent.

One of the consequences of relativity is that you can't really use the concept of "now" for things that are far away.
You can talk about how much time elapsed on someone's clock, which is the same as what they experienced (if they didn't adjust the clock).
You might use "now" if you don't change your speed and you're in an empty universe, but someone else may disagree with what you say (e.g. clock X showing time Y). Both of you are right. The Theory of relativity says how your claims are related.

 

[stevendaryl]

Well from what I quoted from Janus in post #68 I assume Janus was considering it to be the first case. But what case do you think it will be for the following scenario.

There are two spaceships (the "sausage" segments) inside a large tubular spaceship (the "pastry"). They are separated by a distance of 10 light years. All the clocks are synchronised. The two spaceships then at the same point in time (from the "pastry" frame of reference) accelerate to 0.6c.

I'm assuming that the large spaceship is not accelerating?

In that circumstance, then we're in the second situation:

1. Both smaller spaceships feel the same acceleration.
2. The distance between the spaceships remains constant as viewed in the frame of the large spaceship.
3. The distance between the spaceships grows as viewed in the frame of either smaller spaceship. To those on board the smaller spaceships, the ships seem to be getting farther and farther apart.

 

[stevendaryl]

If so then I do find it strange that adjusting the time of F for example in the synchronisation event would alter the relative tick rate.

In Special Relativity, you have to be very careful what you mean by something like "the relative tick rate".

Lets look at our two different scenarios from the point of view of discrete jumps, instead of continuous. That might help explain what's going on.

Instead of firing the rocket continuously, assume that the way the acceleration works is that there is a schedule: At time t=0, rockets are fired to accelerate to speed 10% the speed of light. At time t=1 (according to the clocks on board the spaceships), rockets are fired again to accelerate to 10% of the speed of light relative to the first speed. Etc.

So let's assume that the initial distance between the spaceships is $L$.

The rear spaceship fires its rockets at event $e_1$ with coordinates $(x_1, t_1)$ (using the coordinates of the inertial frame of the larger ship).
The second spaceship fires its rockets at event $e_2$ with coordinates $(x_2 = x_1+L, t_2 = t_1)$. (Same time, different location.)

Now, after accelerating, the spaceships are (momentarily, until the rockets fire again) at rest in a new frame. This new frame has a different coordinate system, $x', t'$ related to the first coordinate system through:

$x' = \gamma (x - vt)$
$t' = \gamma (t - \frac{vx}{c^2})$

where $v$ is 10% of the speed of light. So in this new coordinate system, $e_1$ has the coordinates:

$x_1' = \gamma (x_1 - v t_1)$
$t_1' = \gamma (t_1 - \frac{v x_1}{c^2})$

$e_2$ has the coordinates:

$x_2' = \gamma (x_2 - v t_2) = \gamma (x_1 + L - v t_1)$
$t_2' = \gamma (t_2 - \frac{v x_2}{c^2}) = \gamma (t_1 - \frac{v x_1}{c^2} - \frac{v L}{c^2})$

Now, if we subtract the coordinates, we get:

$\Delta x' = x_2' - x_1' = \gamma L$
$\Delta t' = t_2' - t_1' = - \gamma \frac{vL}{c^2}$

Note: In this new reference frame, we find two weird things:

1. The distance between the rockets has grown from $L$ to $\gamma L$.
2. The two rocket firings were not simultaneous. Since $\Delta t' < 0$, that means that, according to this new reference frame, the front rocket fired earlier than the rear rocket. What that means is that the way things look in this new frame, first the front rocket fires, when its clock shows time $t_1$. Then a time $\Delta t'$ later, the rear rocket fires when its clock shows time $t_1$. So in this frame, the clock in the front rocket is ahead of the clock in the rear rocket by an amount $\Delta t'$, since that's how long it has been at rest in this frame waiting for the rear rocket to fire.

So at this point, you can see that pattern: If every second according to the clock aboard the two rockets, the rockets fire, then the rockets will drift farther and farther apart (as measured by those aboard the rockets) and the clock in the front rocket will get farther and farther ahead, also.

If the two rockets want to keep the same distance, then it's necessary for the front rocket to fire either less frequently, or with less intensity.

 

[name123]

Just before deceleration, the Pastry clock nearest at the time of start, now 0.6*0.8=0.48 light seconds away, would indeed be showing only 0.8*0.8=0.64s. But the new clock, that jumped ahead to 0.36 when the Sausage suddenly accelerated, despite running slower, still show 1.00s when they arrive nearby.
(I'm not sure if I made a mistake in the numbers but it seems reasonable).

So when a member of the sausage crew passes a member of the pastry crew, the sausage crew member will see the pastry crew members clock as showing 1s and their own to be showing 0.8s?

I'm not sure what you're talking about. The theory of relativity describes the one objective truth (as far as we can tell). It is very logical and consistent.

One of the consequences of relativity is that you can't really use the concept of "now" for things that are far away.
You can talk about how much time elapsed on someone's clock, which is the same as what they experienced (if they didn't adjust the clock).
You might use "now" if you don't change your speed and you're in an empty universe, but someone else may disagree with what you say (e.g. clock X showing time Y). Both of you are right. The Theory of relativity says how your claims are related.

I thought that with the theory of relativity there is an eternal universe idea, and that there is no changing "now" in an eternal universe model. There is only what event is simultaneous with what event and the answer to that would be relative. I also did not know that the theory of relativity was an objective truth because is it not a metaphysical theory that shares mathematics with theories such as LET or neo-LET theories.

What I was talking about was the idea that your experience is based on your neural state. With the theory or relativity an observer passing at a high velocity would disagree with an observer in the same rest frame as you with regards to which of your neural events were simultaneous could they not? So what your neural state was would be a relative observation.. So would it not entail a claim that the truth regarding what you were experiencing was relative?

 

[name123]

In Special Relativity, you have to be very careful what you mean by something like "the relative tick rate".

Lets look at our two different scenarios from the point of view of discrete jumps, instead of continuous. That might help explain what's going on.

Instead of firing the rocket continuously, assume that the way the acceleration works is that there is a schedule: At time t=0, rockets are fired to accelerate to speed 10% the speed of light. At time t=1 (according to the clocks on board the spaceships), rockets are fired again to accelerate to 10% of the speed of light relative to the first speed. Etc.

So let's assume that the initial distance between the spaceships is $L$.

The rear spaceship fires its rockets at event $e_1$ with coordinates $(x_1, t_1)$ (using the coordinates of the inertial frame of the larger ship).
The second spaceship fires its rockets at event $e_2$ with coordinates $(x_2 = x_1+L, t_2 = t_1)$. (Same time, different location.)

Now, after accelerating, the spaceships are (momentarily, until the rockets fire again) at rest in a new frame. This new frame has a different coordinate system, $x', t'$ related to the first coordinate system through:

$x' = \gamma (x - vt)$
$t' = \gamma (t - \frac{vx}{c^2})$

where $v$ is 10% of the speed of light. So in this new coordinate system, $e_1$ has the coordinates:

$x_1' = \gamma (x_1 - v t_1)$
$t_1' = \gamma (t_1 - \frac{v x_1}{c^2})$

$e_2$ has the coordinates:

$x_2' = \gamma (x_2 - v t_2) = \gamma (x_1 + L - v t_1)$
$t_2' = \gamma (t_2 - \frac{v x_2}{c^2}) = \gamma (t_1 - \frac{v x_1}{c^2} - \frac{v L}{c^2})$

Now, if we subtract the coordinates, we get:

$\Delta x' = x_2' - x_1' = \gamma L$
$\Delta t' = t_2' - t_1' = - \gamma \frac{vL}{c^2}$

Note: In this new reference frame, we find two weird things:

1. The distance between the rockets has grown from $L$ to $\gamma L$.
2. The two rocket firings were not simultaneous. Since $\Delta t' < 0$, that means that, according to this new reference frame, the front rocket fired earlier than the rear rocket. What that means is that the way things look in this new frame, first the front rocket fires, when its clock shows time $t_1$. Then a time $\Delta t'$ later, the rear rocket fires when its clock shows time $t_1$. So in this frame, the clock in the front rocket is ahead of the clock in the rear rocket by an amount $\Delta t'$, since that's how long it has been at rest in this frame waiting for the rear rocket to fire.

So at this point, you can see that pattern: If every second according to the clock aboard the two rockets, the rockets fire, then the rockets will drift farther and farther apart (as measured by those aboard the rockets) and the clock in the front rocket will get farther and farther ahead, also.

If the two rockets want to keep the same distance, then it's necessary for the front rocket to fire either less frequently, or with less intensity.

Thanks for that, I can see how there would be disagreements in which events were simultaneous.

I was thinking that special relativity allow for clocks to have objectively ticked less than other clocks, for example in the Hafele-Keating experiments. But in the example I gave I think I should have considered the situation using Minkowski space diagrams. I think I was making the same mistake I was making earlier in this thread, which I recognised and then subsequently forgot. Thanks for you patience and detailed response.

 

[Dale]

With the theory or relativity an observer passing at a high velocity would disagree with an observer in the same rest frame as you with regards to which of your neural events were simultaneous could they not? So what your neural state was would be a relative observation..

Neural states form and change far too slowly for relativistic effects to be relevant. For the time scales at which neural states change the brain can easily be considered a point.

 

[SlowThinker]

So when a member of the sausage crew passes a member of the pastry crew, the sausage crew member will see the pastry crew members clock as showing 1s and their own to be showing 0.8s?

Yes. (Assuming they didn't mess with the clocks after start).

I also did not know that the theory of relativity was an objective truth

I meant it in the sense that both Pastry and Sausage crew's observations are correct and precise, yet they disagree on the clock rates etc. Theory of relativity explains that both are simply different views of the same reality. To my knowledge, it doesn't explain why.

What I was talking about was the idea that your experience is based on your neural state. With the theory or relativity an observer passing at a high velocity would disagree with an observer in the same rest frame as you with regards to which of your neural events were simultaneous could they not?

They may disagree on relative ordering of events that are far away from each other, so their ordering doesn't really matter.
Obviously if both observers know Theory of relativity, they will agree on pretty much everything.

 

[name123]

Neural states form and change far too slowly for relativistic effects to be relevant. For the time scales at which neural states change the brain can easily be considered a point.

I was considering that if one neuron was in a different state it would be a different neural state, and I wasn't aware of a minimal time delay between different neurons firing. I didn't think all fired synchronous to a brainwave.

 

[name123]

They may disagree on relative ordering of events that are far away from each other, so their ordering doesn't really matter.
Obviously if both observers know Theory of relativity, they will agree on pretty much everything.

How far away do they have to be? Could there not be a difference in simultaneity if things were 15cm apart if one observer was moving fast and the other was at rest?

 

[SlowThinker]

How far away do they have to be? Could there not be a difference in simultaneity if things were 15cm apart if one observer was moving fast and the other was at rest?

Of course anything farther than 0 has its timing shifted. It depends on the precision which you can achieve. If you can measure nanosecond delays, 15cm is far enough. If you measure in miliseconds, 100km is close. If the observers move slowly relative to each other, the whole Solar system can be considered small. Lorentz transformation quantifies actual time (and space) shifts.

 

[Dale]

I was considering that if one neuron was in a different state it would be a different neural state,

A single neuron’s single action potential is 1 ms so that would mean relativistic effects are irrelevant for brains less than about 300 km in size. However, the state of the brain doesn’t change as fast as the state of a single action potential (neurons encode strength in the frequency of action potentials). A better upper limit for that frequency would be the rate of the gamma waves in an EEG, which tops out at about 150 Hz. That would correspond to a brain size of about 2 million m before relativistic effects would be relevant. The human brain is about 20 cm, so essentially a point compared to the relevant length scales.

 

[name123]

A single neuron’s single action potential is 1 ms so that would mean relativistic effects are irrelevant for brains less than about 300 km in size. However, the state of the brain doesn’t change as fast as the state of a single action potential (neurons encode strength in the frequency of action potentials). A better upper limit for that frequency would be the rate of the gamma waves in an EEG, which tops out at about 150 Hz. That would correspond to a brain size of about 2 million m before relativistic effects would be relevant. The human brain is about 20 cm, so essentially a point compared to the relevant length scales.

I can see your point, but I am not sure that the issue is how often a single neuron could fire, or how long it took. I thought it might be the brain state.

If there were say 100 billion neurons in the brain, and say 10% were firing in any given second and that each of those that fired, fired on average 5 times per second. Then there would be 50 billion neural firings per second, and the number of neurons starting to fire any given nanosecond would be about 50 and the number of neurons ceasing to fire for any given nanosecond would be about 50. Also the firings are not "on" "off" affairs, and the action potential will vary over the firing. How significant it would be to the experience I do not know. But presumably it would be slightly significant else if you counted each ns step as equivalent to the next then when considering the sum of lots of such differences you would consider it to make no difference. In the sense that if e₁ = e₂ and e₂ = e₃ and e₃ = e₄ and so on such that e_n = e_n+1 then e₁ = e_n+1. I have ignored brain waves and the extent to which some of the firings might be "synchronised".

Could the experience not be thought to reflect the simultaneity of neural events?

 

[name123]

Of course anything farther than 0 has its timing shifted. It depends on the precision which you can achieve. If you can measure nanosecond delays, 15cm is far enough. If you measure in miliseconds, 100km is close. If the observers move slowly relative to each other, the whole Solar system can be considered small. Lorentz transformation quantifies actual time (and space) shifts.

I was not thinking about measurement, but theoretical implications. Is what you are experiencing a relative truth?

 

[SlowThinker]

I was not thinking about measurement, but theoretical implications. Is what you are experiencing a relative truth?

I really have no idea where this neurobiology talk comes from.
The brain of an astronaut orbiting Earth works just as well as down here, and neither is affected at all by an alien flying around at 0.9c. Also the alien's brain works just fine. Everyone's viewpoint is equally correct.

 

[Dale]

I can see your point, but I am not sure that the issue is how often a single neuron could fire, or how long it took. I thought it might be the brain state.

I can dig up my neurobiology textbook and find references, but this is standard well known stuff in the field. From a neural signaling perspective an action potential is an all-or-nothing event and the information is encoded in the frequency of action potentials.

the number of neurons starting to fire any given nanosecond would be about 50 and the number of neurons ceasing to fire for any given nanosecond would be about 50.

And there would be a million bazillion molecules jiggling in thermal motion and quantum fluctuations and other things that are irrelevant to “the truth regarding what you were experiencing”. Your own subjective experience should confirm that “what you were experiencing” simply doesn’t change on the scale of nanoseconds and even one nanosecond is about 30 cm at c which is already larger than the brain.

Could the experience not be thought to reflect the simultaneity of neural events?

Not in the sense of the relativity of simultaneity.

 

[name123]

I really have no idea where this neurobiology talk comes from.
The brain of an astronaut orbiting Earth works just as well as down here, and neither is affected at all by an alien flying around at 0.9c. Also the alien's brain works just fine. Everyone's viewpoint is equally correct.

The issue is whether what you are experiencing corresponds to the simultaneous brain activity or not. Perhaps you could make your position clear on this matter.

 

[name123]

Could the experience not be thought to reflect the simultaneity of neural events?

Not in the sense of the relativity of simultaneity.

So if what you are experiencing does not reflect the simultaneity of neural events, what were you thinking it does reflect?

 

[SlowThinker]

The issue is whether what you are experiencing corresponds to the simultaneous brain activity or not. Perhaps you could make your position clear on this matter.

I don't understand your question. My brain is always at rest with respect to itself, and so its parts are always simultaneous in the same way, whether I'm in my bed, or flying an airplane.

 

[name123]

I don't understand your question. My brain is always at rest with respect to itself, and so its parts are always simultaneous in the same way, whether I'm in my bed, or flying an airplane.

Well it depends upon what you mean by simultaneous. Let me put it another way. Are you thinking that the truth of what you are experiencing is relative or is there an absolute truth about the matter?

 

[Dale]

So if what you are experiencing does not reflect the simultaneity of neural events, what were you thinking it does reflect?

Neural events simply don’t happen fast enough for the relativity of simultaneity to matter. Simultaneity in the relativistic sense can never cause anything so it also cannot cause “what you were experiencing”.

 

[name123]

Neural events simply don’t happen fast enough for the relativity of simultaneity to matter. Simultaneity in the relativistic sense can never cause anything so it also cannot cause “what you were experiencing”.

You seem to have avoided answering the question. You seem to have denied that what you are experiencing reflects the simultaneity of neural events, but haven't stated what you think it does reflect. Does it reflect something, and if so, what in the model interpretation that you favour?

Which brings me back to the point I made in post #92

But presumably it would be slightly significant else if you counted each ns step as equivalent to the next then when considering the sum of lots of such differences you would consider it to make no difference. In the sense that if e₁ = e₂ and e₂ = e₃ and e₃ = e₄ and so on such that e_n = e_n+1 then e₁ = e_n+1. I have ignored brain waves and the extent to which some of the firings might be "synchronised".

If you state there is no difference in experience between the slightly different neural events, then it is a slippery slope. If you state that there is no difference that you could distinguish (for example there are RGB numbers we cannot distinguish), then there still is a difference, just not one we can distinguish. And how can the difference not actually be different, how could e₁ = e_n+1 for example.

You also have the problem of not knowing what events would be distinguishable and when they would be distinguishable over time. For example if on RGB events, some R changed later than B in some perspective, maybe it would cross the distinguishable boundary..

Regardless you still haven't explained what your experience reflects.

 

[SlowThinker]

Well it depends upon what you mean by simultaneous. Let me put it another way. Are you thinking that the truth of what you are experiencing is relative or is there an absolute truth about the matter?

Maybe you're misunderstanding the "relativity" in Theory of relativity.

Let's imagine you and I go to view some play in a theater. Your seat is more to the left, mine is more to the right. We both see the same thing, yet it looks different. Both of our views are equally correct. There is no "the one correct" view of the play.

Can you use this example to explain what you mean?

 

[name123]

Maybe you're misunderstanding the "relativity" in Theory of relativity.

Let's imagine you and I go to view some play in a theater. Your seat is more to the left, mine is more to the right. We both see the same thing, yet it looks different. Both of our views are equally correct. There is no "the one correct" view of the play.

Can you use this example to explain what you mean?

Yes two people are looking at you and from their perspectives estimate your experience . If they have differing opinions can they both be right, is it relative, or is what you were experiencing absolute. Can there be experiential scenarios (perhaps put forward by observers moving relative to you at a high speed and an extreme distance) that were simply false. You never experienced those. Is the truth about what you experienced relative?

 

[PeterDonis]

You seem to have denied that what you are experiencing reflects the simultaneity of neural events

That's right; it doesn't. Causal influences can't travel faster than light, and whatever you experience is causally influenced by neural events.

What you experience is that some events in the outside world seem to be simultaneous with some other events. But all of those appearances are constructed by your brain based on information in your past light cone, i.e., information that traveled to you at the speed of light or slower. You never experience anything from events which are actually simultaneous with you, because those events are outside your past light cone and you can't have received any information from them.

 

[SlowThinker]

Yes two people are looking at you and from their perspectives estimate your experience . If they have differing opinions can they both be right, is it relative, or is what you were experiencing absolute.

Maybe one of them saw what's behind me, and neither I nor the other observer saw it.
If the two observers are somewhat intelligent, they'll undestand that they only view some part of the full truth. So do I. But their view may be more complete and more correct than mine.