# Describing entanglement collapse with absolute time

• I
• kurt101
In summary: There is no agreed-upon definition of a light-second. So it's impossible to say for certain how long it would take for entanglement to collapse.
kurt101
TL;DR Summary
Why can't all time and distance in the universe be described in light seconds?
Why can't absolute time be used to describe events? Previously I tried to describe entanglement collapse on this forum in terms of absolute time, but I was told more or less this was not valid. I don't understand why.

If the proper time that we use is based on the fact that the speed of light in vacuum is constant no matter where we measure it then shouldn't we be able to describe any point in our universe relative to all other points in the universe in terms of light seconds where a light second is defined as the distance that light travels in free space in one second?

Can't we effectively use light seconds as both our absolute time and absolute position to describe the universe? In other words after N light seconds of time passing in the universe, I should be able to describe the distance between every point in the universe in light seconds.

Shouldn't I be able to make the statement that entanglement collapse happens in 0 light seconds and avoid the confusing language of saying that observers can't agree when an event really happened and avoid the confusing language of retro-causality?

kurt101 said:
Summary: Why can't all time and distance in the universe be described in light seconds?

Why can't absolute time be used to describe events? Previously I tried to describe entanglement collapse on this forum in terms of absolute time, but I was told more or less this was not valid. I don't understand why.

If the proper time that we use is based on the fact that the speed of light in vacuum is constant no matter where we measure it then shouldn't we be able to describe any point in our universe relative to all other points in the universe in terms of light seconds where a light second is defined as the distance that light travels in free space in one second?

Can't we effectively use light seconds as both our absolute time and absolute position to describe the universe? In other words after N light seconds of time passing in the universe, I should be able to describe the distance between every point in the universe in light seconds.

Shouldn't I be able to make the statement that entanglement collapse happens in 0 light seconds and avoid the confusing language of saying that observers can't agree when an event really happened and avoid the confusing language of retro-causality?
Your question is puzzling. What do you mean by absolute time ? Which clock shows absolute time ?
A light-second is a unit of distance, there is nothing special about it.

Mentz114 said:
Your question is puzzling. What do you mean by absolute time ? Which clock shows absolute time ?
A light-second is a unit of distance, there is nothing special about it.

A light-second can be used as a unit of distance between points when combined with a 3 dimensional direction vector. A light-second can be used as a unit of time when considered as a 1 dimensional direction vector that only goes forward.

Another way to think of this is that I can simulate the universe on my computer by using light-seconds for my time and light-seconds for my distance and completely describe everything. In my simulation, I can say after N light-seconds of running the simulation what the distance in light-seconds between each object is.

kurt101 said:
A light-second can be used as a unit of distance between points when combined with a 3 dimensional direction vector. A light-second can be used as a unit of time when considered as a 1 dimensional direction vector that only goes forward.

Another way to think of this is that I can simulate the universe on my computer by using light-seconds for my time and light-seconds for my distance and completely describe everything. In my simulation, I can say after N light-seconds of running the simulation what the distance in light-seconds between each object is.
So what ? One could use any units and it would make no difference. Why not use light-milliseconds ?

kurt101 said:
In my simulation, I can say after N light-seconds of running the simulation what the distance in light-seconds between each object is.
You can, but the simulation will only be accurate from the point of view of a simulated observer who is not moving. The problem here is that there is no universal observer-independent notion of the distance between objects that are in motion relative to one another.

kurt101 said:
Shouldn't I be able to make the statement that entanglement collapse happens in 0 light seconds
A meter of time is the amount time it takes for light to travel a distance of one meter, so you could say that a light-second of time is the amount of time it takes for light to travel a distance of one light-second - but then you might just as well call it a second instead of a light-second.

But no matter what names you use for your units, there is a basic problem with saying that “collapse happens in 0” units of time. That’s tantamount to saying that the collapse happens at the same time at different locations in space, which conflicts with relativity of simultaneity.

Mentz114 said:
So what ? One could use any units and it would make no difference. Why not use light-milliseconds ?
I don't understand your counter-reply. The constant of speed of light seems like the best source for a universal tick. Whether we use for the units, light-seconds or light-milliseconds is irrelevant to my point and overall question which is why can't we describe events (like entanglement collapse) in terms of absolute time?

Nugatory said:
You can, but the simulation will only be accurate from the point of view of a simulated observer who is not moving.
You mean like God (the programmer)?

Nugatory said:
The problem here is that there is no universal observer-independent notion of the distance between objects that are in motion relative to one another.
If I pause the simulation, each object is going to have a specific distance in light-seconds between every other object. If I run it for a bit and then pause it, I can see exactly how each moving object changes relative to one another. So for all practical purposes it seems the "universal observer-independent notion" is extremely useful in understanding what is actually happening.

And again, if I can model everything in the universe accurately using absolute time, why shouldn't we use it in discussions?

kurt101 said:
I don't understand your counter-reply. The constant of speed of light seems like the best source for a universal tick. Whether we use for the units, light-seconds or light-milliseconds is irrelevant to my point and overall question which is why can't we describe events (like entanglement collapse) in terms of absolute time?You mean like God (the programmer)? If I pause the simulation, each object is going to have a specific distance in light-seconds between every other object. If I run it for a bit and then pause it, I can see exactly how each moving object changes relative to one another. So for all practical purposes it seems the "universal observer-independent notion" is extremely useful in understanding what is actually happening.

And again, if I can model everything in the universe accurately using absolute time, why shouldn't we use it in discussions?
There is no absolute time. Are you thinking of parameter time ? Are you familiar with special relativity ?

kurt101 said:
If I pause the simulation, each object is going to have a specific distance in light-seconds between every other object.
Right, but pausing the simulation and looking at it is basically the same as recording where all the objects are at the same time, and the definition of “at the same time” is inherently frame-dependent.

PeroK
Nugatory said:
A meter of time is the amount time it takes for light to travel a distance of one meter, so you could say that a light-second of time is the amount of time it takes for light to travel a distance of one light-second - but then you might just as well call it a second instead of a light-second.
Obviously time can be translated between seconds and light-seconds, but one is a constant for all objects and the other can only be defined via an equation relative to that constant. For simplicity and understanding it makes more sense to choose the constant.

Nugatory said:
But no matter what names you use for your units, there is a basic problem with saying that “collapse happens in 0” units of time. That’s tantamount to saying that the collapse happens at the same time at different locations in space, which conflicts with relativity of simultaneity.
This point keeps being brought up and it is my understanding that the moderators on this forum don't agree on this. And those that do agree to this point can't effectively back it up other than to say in principle it conflicts, but never explains how in practice it conflicts. And maybe I am wrong on this perception that you can't back it up this in practice, but than I ask you to demonstrate this again in the most straight forward way possible, because I seem to miss it. Or point me to a previous solid explanation. Thanks!

Mentz114 said:
There is no absolute time. Are you thinking of parameter time ? Are you familiar with special relativity ?
I am familiar with special relativity and have read through basic proofs of it. For example I most recently have been reading through the proof from the book "Physics from Symmetry" by Jakob Schwichtenberg. The proof seems mostly straight forward and is based on how different observers in relative motion observe light reflected off a mirror. Even though this seems proof seems simple, I struggle at understanding all aspects of it, and I am open to the possibility that I am misunderstanding.

kurt101 said:
I am familiar with special relativity and have read through basic proofs of it. For example I most recently have been reading through the proof from the book "Physics from Symmetry" by Jakob Schwichtenberg. The proof seems mostly straight forward and is based on how different observers in relative motion observe light reflected off a mirror. Even though this seems proof seems simple, I struggle at understanding all aspects of it, and I am open to the possibility that I am misunderstanding.
I do not know that book. What proof are you referring to ?
There is no such thing as 'at the same time' for all observers.

kurt101 said:
The constant of speed of light seems like the best source for a universal tick.
Realize that the speed of light is constant with respect to the observer of the light. Imagine a pulse of light. I measure the speed with respect to me to be "c". You measure the speed with respect to you to be "c". But according to my measurements, the speed of the pulse of light relative to you will be something other than "c".

kurt101 said:
I am familiar with special relativity...

General relativity tells us that time is influenced by the presence of mass. Time on Earth moves more slowly than time on a GPS satellite in space. So what could be an absolute clock?

Further: if collapse of entanglement were physical, it would still appear instantaneous regardless of reference frame. And if there were some preferred reference frame, this paper would be relevant:

https://arxiv.org/abs/0808.3316

kurt101 said:
Why can't absolute time be used to describe events?

Because there is no such thing.

kurt101 said:
This point keeps being brought up and it is my understanding that the moderators on this forum don't agree on this.

Your understanding is incorrect. There is no disagreement whatever on the fact that there is no "absolute time" in our best current theory of spacetime, which is General Relativity.

There is also no disagreement whatever on the fact that quantum entanglement cannot be used to send information between spacelike separated events (which is the correct technical way to say what is often sloppily said as "faster than light").

What there is disagreement on is the interpretation of quantum mechanics. But all interpretations of quantum mechanics make the same predictions for the results of all experiments, including experiments on entangled particles. So no QM interpretation disagrees on the two statements I made above.

vanhees71
Doc Al said:
Realize that the speed of light is constant with respect to the observer of the light. Imagine a pulse of light. I measure the speed with respect to me to be "c". You measure the speed with respect to you to be "c". But according to my measurements, the speed of the pulse of light relative to you will be something other than "c".
Take the simple thought experiment of a photon reflecting off of a mirror with observers A and B. Observer B is stationary relative to the photon origin and mirror. Observer A starts at the photon origin and moves perpendicular to the origin and the mirror.

Observers A and B disagree about the time it took for the photon to reflect off of the mirror and come back to its origin, but they both assert that the photon traveled at the constant speed of light. Hopefully at this point I have not said anything incorrect or controversial; I am just repeating the thought experiment and derivation from the textbook in front of me "Physics from symmetry" which I assume is similar to many other derivations.

Now do you or anyone else disagree that at any point during this experiment that I as an independent all knowing observer can assign a distance in light-seconds between any two observers in this experiment? You should not disagree since it is assumed in the derivation that the speed of light is constant between any two points in order for the derivation to work.

If I as an all knowing observer can assign a distance in light-seconds between any two observers and all observers share the same value C then I should be able to pause the universe and make a single unique configuration where this has to be true. I should be able to unpause the universe, run it for a while, and after n * C ticks later do this again. If I can accurately model the universe as an all knowing independent observer, shouldn't we acknowledge that thinking in terms of absolute time is a completely legitimate and more importantly a useful way to think of the universe?

To the best of ability to understand; it seems like those who say absolute time does not exist is because they don't want to think in terms of an independent all knowing observer even though the universe can accurately be modeled this way and reproduce all of the same predictions. Is this correct? Or what mistake am I making in coming to this conclusion?

kurt101 said:
Take the simple thought experiment of a photon reflecting off of a mirror with observers A and B. Observer B is stationary relative to the photon origin and mirror. Observer A starts at the photon origin and moves perpendicular to the origin and the mirror.
This description is a bit confusing. I assume you are describing the standard "light clock" derivation, that is repeated in Section 2.1 of "Physics from Symmetry"?
kurt101 said:
Observers A and B disagree about the time it took for the photon to reflect off of the mirror and come back to its origin, but they both assert that the photon traveled at the constant speed of light. Hopefully at this point I have not said anything incorrect or controversial; I am just repeating the thought experiment and derivation from the textbook in front of me "Physics from symmetry" which I assume is similar to many other derivations.
In that book, A, B, and C represent events, not observers. Nonetheless, you can certainly have a light clock in one frame (where the mirrors are at rest) that is also observed from another frame. Yes, the two observers will disagree on the time it takes for the photon to reflect off the mirror and return.
kurt101 said:
Now do you or anyone else disagree that at any point during this experiment that I as an independent all knowing observer can assign a distance in light-seconds between any two observers in this experiment? You should not disagree since it is assumed in the derivation that the speed of light is constant between any two points in order for the derivation to work.
I don't know what you mean by the distance between two observers in this context. (Why not refer to the book, since I have it as well?) What two observers? Anyway, there's nothing special about you and your frame of reference. Any observer can "measure" the distance between two "observers" at a given time and express that distance in light-seconds. Different observers will measure different distances, in most cases. So what?

kurt101 and Mentz114
Doc Al said:
In that book, A, B, and C represent events, not observers.
Sorry, yes of course you are correct. I am not sure why I used A and B to refer to the observers. I was just going from what was in my head and not directly from the book when I named the observers.

Doc Al said:
I don't know what you mean by the distance between two observers in this context. (Why not refer to the book, since I have it as well?) What two observers?
Yes, please use first and second observer, like the book does going forward. First observer is at rest with respect to the origin and second observer is moving with a constant velocity u to the left of the origin.

Doc Al said:
Anyway, there's nothing special about you and your frame of reference. Any observer can "measure" the distance between two "observers" at a given time and express that distance in light-seconds. Different observers will measure different distances, in most cases. So what?
I am thinking hard on this. Thanks.

kurt101 said:
I am thinking hard on this.
Good! Keep at it. (I get the feeling that you think that measuring distances using "light-seconds" somehow makes it universally agreed upon. Not so!)

Get your understanding of special relativity under control before worrying about describing entanglement.

kurt101 said:
do you or anyone else disagree that at any point during this experiment that I as an independent all knowing observer can assign a distance in light-seconds between any two observers in this experiment?

Yes, I disagree. There is no such thing as "absolute distance" any more than there is "absolute time". Nor is there any such thing as an "independent all knowing observer" whose distance and time observations have some sort of privileged or absolute status.

kurt101 said:
You should not disagree since it is assumed in the derivation that the speed of light is constant between any two points in order for the derivation to work.

Yes, it is assumed that the speed of light is constant. That does not mean there is an absolute distance or an absolute time.

kurt101 said:
it seems like those who say absolute time does not exist is because they don't want to think in terms of an independent all knowing observer even though the universe can accurately be modeled this way and reproduce all of the same predictions. Is this correct?

No.

kurt101 said:
what mistake am I making in coming to this conclusion?

The mistake of assuming that there is an absolute distance and time and that there is such a thing as an "independent all knowing observer".

Doc Al
Doc Al said:
Get your understanding of special relativity under control before worrying about describing entanglement.

This is good advice. And with it, this thread is closed since all we are doing at this point is repeating the same things.

## 1. What is entanglement collapse?

Entanglement collapse is a phenomenon observed in quantum mechanics where two or more particles become connected in such a way that the state of one particle affects the state of the other(s), regardless of the distance between them. This connection is known as quantum entanglement.

## 2. How does absolute time play a role in entanglement collapse?

Absolute time refers to a universal time scale that is independent of any observer or frame of reference. In the context of entanglement collapse, absolute time is used to describe the precise moment at which the entangled particles become correlated. This helps us better understand the dynamics of entanglement and its collapse.

## 3. What are the implications of describing entanglement collapse with absolute time?

Describing entanglement collapse with absolute time allows us to better understand the fundamental principles of quantum mechanics and how entanglement works. It also has potential applications in quantum information processing and communication, as well as in the study of the origins of the universe.

## 4. Can entanglement collapse be reversed?

While entanglement collapse is a well-established phenomenon, it is still an active area of research whether or not it can be reversed. Some studies have shown that it is possible to partially reverse entanglement collapse, but fully reversing it remains a challenge.

## 5. How can we measure the collapse of entanglement with absolute time?

There are several proposed methods for measuring the collapse of entanglement with absolute time, including using quantum clocks and measuring the entanglement entropy of the system. However, these methods are still being developed and refined, and further research is needed to fully understand and measure entanglement collapse with absolute time.

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