Computer Performance Evaluation (CPE)

[for_more_ken]

I would like to know if there are any Physics Instructors or Professors who may believe that Queuing Theory as well as Relativity Theory may be relevant to CPE where communications platforms are moving at relativistic velocities with respect to (wrt) each other?

 

[Klystron]

Perhaps an intermediate question in an approriate forum under Other Sciences such as
"How Information Theory (IT) influences error analysis" might establish foundation?

 

[for_more_ken]

Perhaps an intermediate question in an approriate forum under Other Sciences such as
"How Information Theory (IT) influences error analysis" might establish foundation?

Thanks for the tip. I will try posting under Information Technology (IT) as well as this CPE thread.
However, for this post I would like to rephrase my question as follows:
"I would like to know if there are any Physics PhD's, Instructors or Professors who may believe that Relativity Theory may be relevant to the performance of communications platforms that are moving at relativistic velocities with respect to (wrt) each other?

 

[Nugatory]

Thanks for the tip. I will try posting under Information Technology (IT) as well as this CPE thread.
However, for this post I would like to rephrase my question as follows:
"I would like to know if there are any Physics PhD's, Instructors or Professors who may believe that Relativity Theory may be relevant to the performance of communications platforms that are moving at relativistic velocities with respect to (wrt) each other?

There is one large-scale example of communication platforms moving relative to one another in which relativistic effects are relevant: the GPS system with its multiple orbiting satellites. Many physics professors (and non-professors but with the same level of understanding of relativity) were involved in the development of this system; and studying it will bring you up to the state of the art in this area.

This is all pretty general stuff, but then again you've asked a pretty general question. You may get better answers if you can come up with some more specific questions.

 

[for_more_ken]

This is all pretty general stuff, but then again you've asked a pretty general question. You may get better answers if you can come up with some more specific questions.

OK, I have two specific question: There are two synchronized atomic clocks b and d moving along the Earth's orbital path at Earth's orbital velocity vector (v} with respects to (wrt) point a that is fixed on the Earth's orbital path with wrt the inertial frame of our local fixed stars (including our Sun). Point b is moving on the Earth's orbital path and the Path Length between points b and d (PLbd) is perpendicular to the velocity vector (v).

Special Relativity predicts that the two clocks at b and d will tick at the same rates and remain to be in synchronization during a process where a transmission wave front is sent from point b when b passes point a, is then reflected from a mirror at point d and returned to point b. In this process Special Relativity predicts that a timestamp by clock d when the wave front reaches point d will be half way between a timestamp by clock b when the transmission is sent and a timestamp at point b when the reflection from the mirror at d is received at b.

My first question is: "Do these timestamps obey and prove the validity of the Principle of Relativity". That is, will a transmission from point b to a mirror at point d and back to point b when at rest have a "one-way" send response time component that is equal to the "one-way" receive response time component?

My second question is: will such "one-way" send transmission response time component always be equal to the "one-way" receive transmission response time component regardless of the orientation of PLbd (e.g. may PLbd also be aligned with and overlay the velocity vector (v))?

 

[Klystron]

Thanks for the tip. I will try posting under Information Technology (IT) as well as this CPE thread.
However, for this post I would like to rephrase my question as follows:
"I would like to know if there are any Physics PhD's, Instructors or Professors who may believe that Relativity Theory may be relevant to the performance of communications platforms that are moving at relativistic velocities with respect to (wrt) each other?

Thank, you. The admins tell me 'Please, do not cross post'. They can move or merge threads as required. I've been researching and thinking about queues since your original post.

Nugatory's suggestion ...[snip]...significant transmission delays?

[edit: I see the subject line now says 'computer' not network. I'll bow out. ]

 

[Nugatory]

Special Relativity predicts that the two clocks at b and d will tick at the same rates and remain to be in synchronization during a process where a transmission wave front is sent from point b when b passes point a, is then reflected from a mirror at point d and returned to point b. In this process Special Relativity predicts that a timestamp by clock d when the wave front reaches point d will be half way between a timestamp by clock b when the transmission is sent and a timestamp at point b when the reflection from the mirror at d is received at b.

It does, if we make several additional assumptions:
1) We are ignoring the effects of gravity from both the Earth and the sun; that is, we're effectively doing the experiment in empty space.
2) We are ignoring that "moving along the Earth's orbital path" implies moving on a curved path; that is we're assuming straight-line motion. It takes fully six months for the Earth to change its direction by 180 degrees, so straight-line is a pretty good approximation when the clocks are separated by only a few light-seconds.
3) We synchronized the clocks so that they both read zero at the same time according to an observer who is at rest relative to the clocks. (It also works if the synchronization is done by an observer moving perpendicular to the line between the two clocks, although in this case the synchronization procedure is more complicated without contributing any additional insight into the physics involved).
Without these assumptions, the clocks won't in general be synchronized. But even with these assumptions, so that the clocks are synchronized...

My first question is: "Do these timestamps obey and prove the validity of the Principle of Relativity". That is, will a transmission from point b to a mirror at point d and back to point b when at rest have a "one-way" send response time component that is equal to the "one-way" receive response time component?

Yes, the timestamps will come out that way.

This result results "obeys" the principle of relativity and the postulate that the one-way speed of light is equal to the round-trip speed. However, it does not "prove" anything. Our synchronization procedure will necessarily have assumed these postulates (depending on the details, the assumption may be well-hidden, but it's there) so all we've shown is that when we assume something is true we can get results consistent with that assumption.

My second question is: will such "one-way" send transmission response time component always be equal to the "one-way" receive transmission response time component regardless of the orientation of PLbd (e.g. may PLbd also be aligned with and overlay the velocity vector (v))?

Yes, provided that the clocks are synchronized as in #3 above. The easiest way to see this is to analyze the problem in a frame in which the two clocks are at rest; now the possibility that someone else is moving in some direction at some speed is clearly irrelevant to the behavior of the clocks.

 

[Nugatory]

It begs the question: "how does Ethernet operate in space as distance among network nodes increase?".

Not very well, but this has nothing to do with relativity, it's more a matter of designing protocols that work well under conditions of high latency and low bandwidth. Googling for "TCP/IP Earth orbit" or "ethernet Earth orbit" will find a bunch of interesting discussion.

 

[PeterDonis]

Since the OP is unwilling to provide valid sources, this thread is closed.