The Logic Behind Einstein's Relativity of Time

[Boffin]

Relativity says that your local time is measured by clocks in your rest frame.

Thanks for clearing up some issues Tom. But one remains. If the commanders of the spaceship are getting the astronomical data while in their rest frame, for example they are seeing the light coming through a window of the spaceship, and their computer is also in their own rest frame, then wouldn't the celestial clock they are using be said to be operating in the spaceship commanders' rest frame? And in this case wouldn't the celestial clock would be showing a different time than the portable clock based on atomic vibrations they have along? So now there is going to be two different clocks with two different times but both in the commanders' rest frame?

 

[quantumdude]

OK, I was sloppy so let me clear it up. When I said,

Relativity says that your local time is measured by clocks in your rest frame.

what I meant was that your local time is measured by clocks whose rest frame is also your rest frame. Of course, every clock exists and operates in every rest frame. But not every clock has the same rest frame as the spaceship commander's. It is only those clocks that keep the correct time for that frame. Since the Earth-Sun system is not at rest with respect to the spaceship, it is not keeping the correct time in the frame of the ship.

 

[Ragnar Thor]

Let's put it like this.

1. The laws of nature are the same to every observer no matter what his frame of reference is.

2. No experiment can reveal in which frame of reference you are. It can only reveal your movement or position relative to someone else.

3. By changing velocity or heading you can change your frame of reference.

4. It is possible to abandon and join someone else's FR.

- - -

Now is the year 2525. The Rulers of the Earth have realized using their highly advanced computers that the Earth is in great danger. There is a 97,67% possibility that the invisible Venus-pushing evil fairy will crush Earth in 13,5 Earth years.

Since you can not easily stop invisible fairies 6 of the best space shuttles are manned and each is sent on a mission to a given place in space. Those places are to be possible amnesties for the human race.

It is imperative that all of the shuttles return at the same time, that is exactly 10 Earth years after departure. That is why command posts are put up as well as great navigators and mathematicians are put on the shuttle, each with his or her own super computer.

Each shuttle has its own frame of reference (or even one frame going out and another one coming back). At the moment they leave the earth’s frame they start two types of clocks. A regular clock and a computer clock which calculates Earth time.

Now exactly ten years later all the shuttles come back and all their information is downloaded onto Earth’s mega computer which calculates the best line of action.

At the very moment they came back to Earth's FR they stopped both the clocks onboard.

---

Now I think it would not only be logically correct but also in perfect harmony with our very notion of time to state that if two or more people leave the same FR at the same time and return to it simultaneously, then they have been away for the SAME AMOUNT OF TIME.

However this does in no way contradict that one of them might have aged more than the other(s).

In this case we would simply say so and so many minutes in one frame is the same time as so and so many minutes in another frame. It should be possible to account for every conceivable frame like this.

So we have

FE: (Earth’s frame of reference) 10 y = F2: 7 y = F3: 9,3 y = F4: 4,5 y ...

And those numbers are not relative in any sense of the word. As long as it is F2 you are in you need to speed your clock up by 30% to get the accurate time.

We can therefore define a Universal time. It doesn't have to be Earths, it could be anything, and then define time in every other FR in relation to this one.

---

We would then have a highly useful concept of universal time (if space travel will become a real possibility, not to speak of communications with beings far away, this will most certainly be done). It would also be logically correct because if two people can leave a FR and return to it at the same time they certainly have been away for the same amount of time.

And it would be the answer to the $65.4K question (or what ever it was).

 

[Ragnar Thor]

Now Tom.

You have again and again pointed at your writings at the philosophy formum.

I did read it and it simply confirmed what I already knew. You haven´t understood what I have been talking about.

This has absolutely nothing to do with Popper or falsificationism. This isn't about finding proof to contradict Einstein's claims.

The question is about logic and the definition of terms.

Einstein states that by making time relative you can show how the laws of nature are the same to everyone.

Which is a statement like this one.

A -> B

Now of course testing has showed B.

But that isn't enough to state A.

You yourself took this very example in the philosophy forum.

What I am saying is that by sticking to a Universal time and assuming that relativity is not about time but something else you might have the same results. Therefore:

C -> B

Since the results ARE the SAME we have no way of falsifying one rather than the other.

Indeed this is a minor theory of relativity:

If two clocks show different times relative to each others you will have no way of saying which is true:

A: time passes at different rates
B: the clocks work at different speeds

If you define time as the speed of the clock you still are not out of the loop. You could turn it around and say: That which clocks measure is relative. You call it time. You can do that but that is trivial.

Time is something else and such a time is both a useful and relevant concept.

 

[selfAdjoint]

Einstein states that by making time relative you can show how the laws of nature are the same to everyone.

Which is a statement like this one.

A -> B

Now of course testing has showed B.

But that isn't enough to state A.

Not so.

Enstein stated that

A. Local physics is the same in all inertial frames.
and
B. The speed of light is the same in all inertial frames.

And from these two postulates he proved (derived logically)

C. "Time is relative" - i.e both simultenaity and rate of time passage depend on your inertial frame.

This is a statement of the form A ^ B -> C.

C has been observed experimentally (e.g. lifetime of atmospheric muon). Other experimental observations by the thousand in accelerators give us further confidence in A and B. There does not appear to be anything logically wrong with the derivation of C from A and B, and the experimental evidence gives us confindence that the mathematico-logical model correctly represents reality to a workable level of accuracy.

 

[Ragnar Thor]

Not so.
Enstein stated that
A. Local physics is the same in all inertial frames.
and
B. The speed of light is the same in all inertial frames.
And from these two postulates he proved (derived logically)
C. "Time is relative" - i.e both simultenaity and rate of time passage depend on your inertial frame.
This is a statement of the form A ^ B -> C.
C has been observed experimentally (e.g. lifetime of atmospheric muon). Other experimental observations by the thousand in accelerators give us further confidence in A and B. There does not appear to be anything logically wrong with the derivation of C from A and B, and the experimental evidence gives us confindence that the mathematico-logical model correctly represents reality to a workable level of accuracy.

I dare to disagree.

You could just as well say that Einstein simply expanded Galileo's relativity and said:

All physics (including the findings of Maxwell and the speed of light) is the same to...

Which can be written simply as A -> B

But please have in mind that it really is the other way around when put up as a logical example.

If time is relative -> the laws of physics...

I am simply saying that it seems to me that you don't have to give up the idea of Universal time to agree with what Einstein derived from time being relative. You might take another path. And then come up with:

C -> B

And if both

A - > B

and

C -> B

can be correct it would be a logical fallacy to claim that the existence of

B

proves

A

rather than

C.

And before Tom gets wound up over this quoting Popper, just think about it. The theory of relativity is not an a posteriori scientific theory. It is just as much a priori theory then validated by physical evidence.

Since what I am saying is that both A and C could explain B (and really that we would have no way of claiming one rather than the other) you can't falsify one without doing the same to the other.

I have never claimed that Einstein was wrong. I have simply said that it seems as a logical fallacy to me to choose time as the variant when you could have chosen something else.

 

[russ_watters]

Now I think it would not only be logically correct but also in perfect harmony with our very notion of time to state that if two or more people leave the same FR at the same time and return to it simultaneously, then they have been away for the SAME AMOUNT OF TIME.

According to the clock on Earth, yes.

However this does in no way contradict that one of them might have aged more than the other(s).

True.

In this case we would simply say so and so many minutes in one frame is the same time as so and so many minutes in another frame. It should be possible to account for every conceivable frame like this.
So we have
FE: (Earth’s frame of reference) 10 y = F2: 7 y = F3: 9,3 y = F4: 4,5 y ...
And those numbers are not relative in any sense of the word. As long as it is F2 you are in you need to speed your clock up by 30% to get the accurate time.

Sure, you could do that...

We can therefore define a Universal time. It doesn't have to be Earths, it could be anything, and then define time in every other FR in relation to this one.

You could also call it "arbitrary earth-time", which would be a more descriptive name for it anyway. Calling it "Universal time" doesn't make it any more truly universal tham the universal time (UT/GMT) that we already use. It would only be "unversal" insofar as you force people to use it all the time.

We would then have a highly useful concept of universal time (if space travel will become a real possibility, not to speak of communications with beings far away, this will most certainly be done).

Sure, and such concepts are already in use with the GPS system - the clocks on the satellites are pre-programmed to run at a rate that keeps them synchronized with earth-based clocks.

And it would be the answer to the $65.4K question (or what ever it was).

No, the $64k question is why would we want to rewrite the laws of physics to always use the earth-based reference frame for time. Your example - and the GPS system - may be a specific case where we would want to use Earth as a "home base frame", but they don't answer the $64k question of why would you always want to do that (that's what it means to rewrite the laws of physics to include it). There are an infinite number of scenarios where it would not make sense to reference a time to Earth's frame. For example, if one of those astronauts in your scenario asks when lunch is, what do you tell him? Three weeks?

 

[quantumdude]

Rangar, I am going to answer two of your posts at once.

Now I think it would not only be logically correct but also in perfect harmony with our very notion of time to state that if two or more people leave the same FR at the same time and return to it simultaneously, then they have been away for the SAME AMOUNT OF TIME.

Yes, you can say that. But you can only say it because the start and stop points of every ship's journey is the same. When there is no spatial separation in the clocks upon starting and stopping, then according to relativity all inertial observers will agree that the starting and stopping of the clocks is simultaneous. All inertial observers will agree that the ships have been gone for the same amount of time.

They will just disagree on what that time was.

We can therefore define a Universal time. It doesn't have to be Earths, it could be anything, and then define time in every other FR in relation to this one.

No, you couldn't define it on that basis. You haven't taken into account what happens when two clocks don't start and stop at the same location. If an observer in one inertial frame says that the starting and stopping of the clocks is simultaneous, then no other inertial observer will agree with him. So your "universal time" isn't so universal after all.

Next post...

Now Tom.

You have again and again pointed at your writings at the philosophy formum.

I did read it and it simply confirmed what I already knew. You haven´t understood what I have been talking about.

I have never seen such a clear cut case of the pot calling the kettle black. You say that you read the links I gave you, so it must be the case that you didn't understand what you read.

This has absolutely nothing to do with Popper or falsificationism. This isn't about finding proof to contradict Einstein's claims.

You are the one who brought up the fallacy that arises from confirmation theory, you are the one who noted that scientists can only prove others wrong rather than prove themselves right, and you are the one who was confused about the "logical trap" that one falls into when applying confirmation theory to scientific invesitgation. I was merely responding to those points of yours. I am sorry that you cannot see how the information I gave you is relevant, but I think it is perfectly obvious that you don't really understand what you want to talk about.

The question is about logic and the definition of terms.

Einstein states that by making time relative you can show how the laws of nature are the same to everyone.

No, he didn't and if you make one more crackpot post like this I am going to lock this thread and issue a formal warning. I gave you a link to Einstein's paper which says exactly how he developed relativity, and this isn't it. Either read the paper or drop the subject.

Which is a statement like this one.

A -> B

Now of course testing has showed B.

But that isn't enough to state A.

You yourself took this very example in the philosophy forum.

This is not the logical structure of relativity. See selfAdjoint's post for the correct structure. The rest of this post, as well as your last post, is equally off base so I am going to skip it.

 

[Ragnar Thor]

Actually on page 2 the Now for the 65.4K question was asked. And then it was simply this:


"Why the blazes would anyone want to do that?"

Nothing about always.

However this is not entirely the point.

The point is this:

Instead of saying TIME is relative you could say that THINGS in the Universe are relative.

That is: define their relative speed and headings and then state: In the SAME AMOUNT OF TIME (no mention of Earth time rather than any else) bodies in FR 1,2,3,4,5 will have the relative aging of: 1:1,3:1,5:2,4:3.

Just as we can say that if a person smokes it can speed up aging x%.

We don't have to deny that Universal time exists to accept every conclusion of Einstein. Frankly time is always measured against "some things happening" (and has been so at least from the day of Aristotle) and there is no way to see which of the two happened:

A: Time slowed down.
B: I sped (?) up.

Unless of course you define "time" as the "speed of me".

But a multitude of things can speed me up (such as smoking) so this is in no way the only definition of time.

 

[quantumdude]

And with that, we are done. I think we have been patient enough.