Thought Experiments

[Dekan]

Hello studiot, are you being wilfully obtuse

[studiot]

 

Posted Today, 10:34 PM

Hello studiot, are you being wilfully obtuse

 

Um, how do you make that out?

 

Does "mach 1" not have any units?

[xyzt]

 

Um, how do you make that out?

 

Does "mach 1" not have any units?

m/s

[studiot]

 

Does "mach 1" not have any units?

 

 

m/s

 

 

Funny I could have sworn it was a dimensionless number last time I looked.

 

http://en.wikipedia.org/wiki/Mach_number

Edited September 19, 2014 by studiot

[xyzt]

 

Funny I could have sworn it was a dimensionless number last time I looked.

 

http://en.wikipedia.org/wiki/Mach_number

 

 

Nope

[studiot]

Well if you want to use comic book references I don't see how it pertains to special relativity.

 

And it doesn't alter the fact that although we colloquially talk of the train 'being in one frame' and the platform being in another, the truth is that both are 'in' both frames.

And I'm sure you know this perfectly well.

[swansont]

He only claims that the mind experiment in question does not explain the real observations that we make, not that the data from these observations are false. I agree with him, whatever the way you turn that mind problem around, there is no way out, so why not admit that there might be something that we do not understand about motion yet?

 

Relativity is mathematically self-consistent, so if there is a conflict in a thought problem, it is because one has assumed something that over-constrains the problem and prevents a solution, i.e. something unphysical has been assumed, or two conflicting things that can't both be true have been assumed. IOW, he is wrong. Further, he has made claims that are factually incorrect and others that are logically flawed. IOW, he is wrong.

 

Wrong positions are to be discarded, not given equal consideration.

[Le Repteux]

You may be right, but how to tell? There are so many discussions on relativity, and so many not discussing the data but the logic, that it is normal to doubt. These do not happen about the laws of gravitation, or about the laws of electromagnetism. When will Relativity become a law so that we stop arguing about it?

[xyzt]

You may be right, but how to tell? There are so many discussions on relativity, and so many not discussing the data but the logic, that it is normal to doubt. These do not happen about the laws of gravitation, or about the laws of electromagnetism. When will Relativity become a law so that we stop arguing about it?

Cranks have always have had doubt directed at relativity. To a lesser extent they have had doubts directed at QM.

They doubt what they cannot understand.

Edited September 20, 2014 by xyzt

[Le Repteux]

Hi xyzt, does the name Howard tell you something? He also chases cranks on another scientific forum, proudly exhibiting their heads on the top of its car as if they were deers. You may understand maths, but you certainly do not understand individuals. What you do is not intelligent, it is instinct.

Edited September 20, 2014 by Le Repteux

[studiot]

 

He also chases cranks on another scientific forum, proudly exhibiting their heads on the top of its car

 

 

Don't all cars have cranks?

 

[xyzt]

Hi xyzt, does the name Howard tell you something? He also chases cranks on another scientific forum, proudly exhibiting their heads on the top of its car as if they were deer. You may understand maths, but you certainly do not understand individuals. What you do is not intelligent, it is instinct.

So others have exposed your fringe ideas. Good.

[imatfaal]

!

Moderator Note

 

OK - Everyone

 

Please address the arguments of other posters - do not characterise their motives, attack their person, or use insulting language/nomenclature.

 

This thread is close to being locked. Do not respond to this moderation

 

[christopherkirkreves]

Hello again.

 

I understand that you all think I’m just blinded to the truth that has been clearly laid out here before me by everyone in this thread due to me be so wedded to my own odd interpretation of this theory I can’t see anything other than my own ideas.

 

Okay.

 

There is an old trick in therapy (and perhaps this thread needs some therapy) where the one party is required to say what he (or she) believes the other party is saying.

 

One of the hardest parts for me in this thread is that I’m being told that I’m wrong by several different people, but they are telling me that I am wrong for several different reasons, and those different reasons don’t necessary correspond with one another.

 

And so, what follows is my attempt to say what I believe you all are saying, and to put these various ideas into one argument, and to then also include what I believe is the consequences of these arguments.

 

The easy response to this is to say “Christopher, you’re just saying the same thing over and over and not listening.” And you may very well be justified in saying that because you really believe that I’m not trying to create some daylight in this discussion where we can really point out our disagreements and then discuss them.

 

I’m trying.

 

-----

 

This is what I think you all are saying (and the consequences):

 

When

it comes to the “Two Lightning Bolt Strikes” thought experiment

if

by stipulating that the two lightning bolt strikes occur simultaneously

in one inertial frame of reference

then

this means the man in that inertial frame of reference will see the two

flashes of light at the same time

and

this means the man in the other inertial frame of reference will see

(encounter) one flash of light before the other

then this means

the man in the one frame of reference is actually at rest

and

the man in the other frame of reference is actually in motion

and so

the “Two Lightning Bolt Strikes” thought experiment is a test

of absolute rest

because

for the one man to encounter the two flashes of light at the same time

he must remain at rest at the midpoint between where the two flashes

of light occurred

and

for the other man to encounter one flash of light before the other he must

move away from the midpoint

unless

by stipulating that the two flashes of light occur simultaneously in one

inertial frame of reference

means also

stipulating that the two flashes of light do not occur simultaneously for the

man in the other inertial frame of reference

and so

neither man moves

and so

this is then not a test of absolute rest

but rather

it is the two flashes of light that move to both men

but since

it was stipulated that the two flashes of light occurred simultaneously for the

one man and this also means it is stipulated that the two flashes of light do not

occur simultaneously for the other man

and so

the two flashes of light travel equal distances at equal velocities to both men,

but for the one man they left their points of origin at the same time, and so he

encounters them at the same time, while for the other man they left their points

points of origin one before the other, and so he will encounter one before the

other

but this means

the conclusion of this thought experiment (“events which are simultaneous in one

inertial frame of reference are not simultaneous in another”) is also a stipulated

to premise of this thought experiment.

 

For those of you who think that the “Two Lighting Bolt Strikes” thought experiment does not prove anything but is just a demonstration of how Relativity works will be just fine that this thought experiment assumes as one of its premises “events which are simultaneous in one inertial frame of reference are not simultaneous in another.”

 

But if you think that this thought experiment proves something then the above logic shows that the “Two Lightning Bolt Strikes” thought experiment does not work, because it either leads to a test of absolute rest (which is unacceptable) or it assumes it conclusion (which is also unacceptable).

 

Either way, whether Einstein intended prove or did not intent to prove “events which are simultaneous in one inertial frame of reference are not in another” he does not.

 

And so, with many of you I am in agreement, he does not prove this.

 

However, Comstock’s “One Light Bulb in a Moving Car” thought experiment, given the four axioms, does prove (in the sense of the thought experiment) “events which are simultaneous in one inertial frame of reference are not simultaneous in another.” And he only needs to assume the four axioms to do this and not also to assume the conclusion “events which are simultaneous in one inertial frame of reference are not in another” to do this. And in his thought experiment both men remain at rest and so there is no danger of having to say one is actually at rest and the other is actually in motion and so becoming a test of absolute rest.

 

Now, if any of you who agree with me that Einstein’s “Two Lightning Bolt Strikes” thought experiment does not prove “events which are simultaneous in one inertial frame of reference are not in another” (because he did not intend to (or even though he intended to)) also think that Comstock’s thought experiment does not prove “events which are simultaneous in one inertial frame of reference and not simultaneous in another” in the same way as Einstein’s does not, then make you case. Let’s switch roles. You make an affirmative case as to why Comstock failed, and I will take on your role as the critiquers.

 

And, of course, you could always just respond with “Christopher, you just don’t listen, so you wrong, but I’m just done wasting my time.”

 

Okay.

 

I think I’m listening. I think I’m trying very hard to understand your various, and at time conflicting, critiques of me. And where I have agreed I have admitted to be wrong, and where I have disagreed I have tried to state the reason(s) why. And where I have felt like I have been told I’m wrong for the same reason over and over, I have tried to vary my responses to try to get to a clearer understand of our differences.

 

And he above piece of logic is, yet again, an attempt at a varied response.

 

-------------

 

To studiot:

 

“I do not like holding discussion with those who declare "whatever you are going to say is irrelevant", without knowing what I actually want to say.”

 

Really?

 

I believe I have put up with a lot of unnecessary hate and rudeness in this thread that did not in any way advance the discussion.

 

And I believe I answered your questions the first time you asked them.

 

And while it may have been rude of me to anticipate your response and so then also give my response (“it is irrelevant”) to your anticipated response when answering your question again (“It is all in the embankment”), are you, a denizen of the Internet and this forum, saying that what I did was so rude (and I’ll admit there was some rudeness to it) and so far beyond what is commonly found in this and other forums that your sensibilities keep you from stating the “explanation of the relativity of simultaneity” that you had already ready for me, but you just needed to know the “all important” point of where I believed the two lightning bolt strikes occurred (which is “in the embankment”)?

 

--------

 

To swansont:

 

“Certainly not 1905, when Einstein derived them from the postulate of invariant c,”

 

You are right.

 

At various times Einstein constructed his theory is various ways.

 

And you are right, in 1905, in “On The Electrodynamics of Moving Bodies,” he proves “clocks synchronized in one inertial frame of reference are not synchronized in another,” based on the postulate of the invariant nature of light for all observers, and then by proving length contraction.

 

“Observers moving with the moving rod would thus find that the two clocks were not synchronous while the observers in the stationary system would declare the clocks to be synchronous.” (see A. Einstein, “Zur Elektrodnamik bewegter Koper,” Annalen der Physik, 17, 1905)

 

But by 1916 he had changed the structure of his theory. In his 1905 thought experiment he had to rely on clocks to prove the relativity of simultaneity. And in his 1905 thought experiment he had to first work though a small bit of simple math, and then first prove “length contraction,” to then prove the relativity of simultaneity.

 

In his 1916 book (as well as in his 1916 paper) he seems to be doing what Comstock had done, and he seems to think he is doing it better (because he eliminated the need to clocks).

 

So, yes, you can go through the various papers published by Einstein and make the argument that the Lorentz transformations are not based on the relativity of simultaneity.

 

But, in his book, that was, I think, without argument, his most prominent construction of his theory, and which he continued to stick to for the rest of his life (lasted edited by him in 1952 three years before he died in 1955), he is, I believe, in his theoretical construction, in this theoretical construction, basing the Lorentz transformations on the relativity of simultaneity (as well as saying this is what he is doing in his 1916 paper).

 

But, you are right, there are lots of different papers out there, and if you want to pull quotes from them and say he is really overall, or more prominently, or more generally, constructing his theory in other way, if you make your case based on his other writings, then we can debate.

 

“That “every inertial frame of reference has its own particular time”? That's a conclusion of the Lorentz transform, which is derived from the invariant c postulate.”

 

If you believe that the way he constructed his theory in his book is not his main and final constructed form of his theory, but rather, there a better way to say that his theory is constructed, then, yes, and I’d love to see your outline of how he constructed his theory.

 

But, if you believe that the final and main form of his theory can be found in his 1916 book, then at the end of the “Two Lightning Bolt Strikes” thought expedient he concludes with “We thus arrive at the important result: Events which are simultaneous with reference to the embankment are not simultaneous with respect to the train and vice versa (relativity of simultaneity). Every reference-body (co-ordinate system) has its own particular time; unless we told the reference-body to which the statement of time refers, there is not meaning in the statement of the time of an event.” (pp. 30-31)

 

Now, to me, it seems clear that he believes he has just proven, via the “Two Lightning Bolt Strikes” thought experiment, that “events which are simultaneous in one inertial frame of reference are not simultaneous in another” [my paraphrase], and then, upon proven this, he then immediate makes the logical deduction “Every reference-body … has its own particular time.”

 

I don’t believe that when he says “Every reference-body … has its own particular time,” that he is expecting that the reader will realize that he is referring to his 1905 proof; especially sense he does not refer to it.

 

It seems to me he is doing something very different here than he did in 1905.

 

And it seems to me what he is doing here is proving “events which are simultaneous in one inertial frame of reference are not in another” on page 31 and this using this, implicitly, as a justification of the premises of the Lorentz transformations on page 34.

 

But, again, I agree, if you go through all of his papers, you can make the case that he constructed his theory otherwise.

 

“and who are you to say this wouldn't be intuitive for anyone but yourself”

 

When people first come to studying the Theory of Relativity, whether that is a brilliant young sixth grader who will eventually go onto to get a Ph.D. in this field, I believe he and all of the rest of us first come to this theory with the common sense ideas that simultaneous events and length and time do not change if you are in motion relative to them.

 

If you believe that some people, before studying the Theory of Relativity, have the “common sense” notion that “events which hare simultaneous in one inertial frame of reference are not in another” then okay, you must hang with a different crowd of people than I do.

 

And so, only for my crowd then and not yours, is this counterintuitive and so must be justified.

 

---------------

 

To pzkpfw:

 

“We've been over that. This is where I give up”

 

Well, you could make the argument that since the two lightning bolt strikes do occur in the embankment and since they do occur “at the same time” Einstein is stipulating that the two lightning bolt strikes occur simultaneous in the embankment frame while leaving whether they are or are not simultaneous in the train frame, at this point in the thought experiment, unknown or undetermined.

 

(I don’t remember you making this argument, but if you did, I’m sorry.)

 

However, if this this your argument, you then make the additional argument (in my opinion of your argument) that Einstein then reasons that since the two men are at two different points when the flashes of light reach them, then logic dictates, that if they are simultaneous for the man on the embankment then they are not simultaneous for the man in the train.

 

At no point in Einstein’s language can I find him making (can I read into it him making ) the argument that “logic then dictates that the other man must see the one flash of light before the other because he will be at a different point than the man on the embankment when the flashes of light reach him” (or anything to that effect)).

 

What I see Einstein doing is saying the man in the train is actually in motion and the man on the embankment is actually at rest. “Now in reality (considered with reference to the railway embankment) he is hastening towards the beam of light coming from B, while he is riding ahead of the beam of light coming from A” (p. 30); which is beyond any of the most flexible and open-minded aspect of my logic to see as anything other than a statement, by Einstein, of motion, and of who is and who is and who is not in actual motion.

 

If you can read that statement quoted in another way that does not necessarily mean motion, then please let me know.

 

And so, if by saying Einstein stipulates who sees the two flashes of light simultaneously and then logically deduces that the other man cannot see them simultaneously, this means also stipulating who is actually at rest and who is actually in motion, then this thought experiment is a test of absolute rest.

 

(And this must be the case. For one man to see the two flashes of light at the same time, and given that they occurred at equal distances from him, then he cannot move. And for one man to see the one flash of light before the other, and given that they occurred at equal distances from him, then he must move. And so then we know who is actually in motion and who is actually at rest in this thought experiment. Thus absolute rest. And the only other way out of this logic is to assume the conclusion (which those who think that this thought experiment does not prove anything happily do), and so we end up with Einstein’s “Two Lightning Bolt Strikes” thought experiment does not prove “events which are simultaneous in one inertial frame of reference are not simultaneous in another” while Comstock’s “One Light Bulb On A Moving Car” thought experiment does prove “events which are simultaneous in one inertial frame of reference are not simultaneous in another” as was detailed out above).

 

-------

 

To Le Repteux:

 

Thank you.

 

And if any of them take up the challenge to disprove that Comstock, unlike Einstein, proves “events which are simultaneous in one inertial frame of references are not in another” it will be interesting to see the kind of thinking that ensues when it is I critiquing their affirmative stance.

 

--------

 

To studiot:

 

“The point is that the lightning (along with everything else in the universe) is not in any frame at all.”

 

When a bolt of lightning moves from a thunder cloud at rest relative to Earth (or, in other words, rotation along in the atmosphere along with the rotation of Earth) to the planet, it is in the inertial frame of reference of the Earth (ignoring the curved rotational aspects).

 

It is moving from one object to another in one inertial frame of reference.

 

It is only when, in Einstein’s thought experiment, the moving flashes of light are moving to objects that may be consider moving or not moving relative to the moving flashes light that the problems arise.

 

--------------

 

To Le Repteux:

 

“He only claims that the mind experiment in question does not explain the real observations that we make, not that the data from these observations are false.”

 

Right. I have not questioned any of the empirical evidence that confirms this theory. I am only saying that I think there is a problem with the theory (specifically part of the theoretical structure) itself.

 

-------

 

 

Thank you all!

 

Cheers!

 

- Christopher

[xyzt]

 

This is what I think you all are saying (and the consequences):

 

When

it comes to the “Two Lightning Bolt Strikes” thought experiment

if

by stipulating that the two lightning bolt strikes occur simultaneously

in one inertial frame of reference

then

this means the man in that inertial frame of reference will see the two

flashes of light at the same time

and

this means the man in the other inertial frame of reference will see

(encounter) one flash of light before the other

then this means

the man in the one frame of reference is actually at rest

and

the man in the other frame of reference is actually in motion

and so

the “Two Lightning Bolt Strikes” thought experiment is a test

of absolute rest

There is no test for "absolute rest" because .... there is no such thing as "absolute rest". It is refreshing to see that you will never understand not only the special relativity but also its predecessor, the galilean relativity. Of course, none of this will stop you from posting and re-posting the same misconceptions over and over in ever longer posts.

Edited September 20, 2014 by xyzt

[swansont]

 

But by 1916 he had changed the structure of his theory.

 

No, he expanded the applicability of relativity to include gravitation, but special relativity did not change.

[pzkpfw]

I am utterly mystified as to why, after multiple explanations, you cannot understand the meaning of the words I've underlined for you. ...

 

...

What I see Einstein doing is saying the man in the train is actually in motion and the man on the embankment is actually at rest. “Now in reality (considered with reference to the railway embankment) he is hastening towards the beam of light coming from B, while he is riding ahead of the beam of light coming from A” (p. 30); which is beyond any of the most flexible and open-minded aspect of my logic to see as anything other than a statement, by Einstein, of motion, and of who is and who is and who is not in actual motion.

 

If you can read that statement quoted in another way that does not necessarily mean motion, then please let me know.

...

He continues that paragraph with "Observers who take the railway train as their reference-body ...". Section 9 also has near the start: "People travelling in this train will with a vantage view the train as a rigid reference-body (co-ordinate system); they regard all events in reference to the train.". Clearly there is no absolute motion involved. Both observers may consider themselves as at rest, and the other as in motion. That's a cornerstone of relativity.

 

You seem to have the same problem (selective reading) with ...

 

Are two events (e.g. the two strokes of lightning A and B) which are simultaneous with reference to [ 31 ] the railway embankment also simultaneous relatively to the train?

You've twisted that in several ways, also.

Edited September 21, 2014 by pzkpfw

[Phi for All]

I have not questioned any of the empirical evidence that confirms this theory. I am only saying that I think there is a problem with the theory (specifically part of the theoretical structure) itself.

 

!

Moderator Note

You don't question the evidence, which means you don't question the math.

 

BUT... you question the theory based on a thought experiment, which you've been told repeatedly can't EVER be used to disprove a theory. The mathematical consistency should scream out to you that you're focusing an inordinate amount of effort on a physics dilemma that only appears when you ignore the language of physics in favor of the less precise language of thought.

 

Please consider that, if what you say above is true, you acknowledge that the theoretical structure of relativity is mathematically sound. So the real problem you have is that you can't easily check the math to resolve your misunderstanding, which keeps leading you into more rabbit-holes.

 

This thread doesn't seem to be helping you understand. It seems very important to you and we all respect that, but discussing it like this hasn't done any good (for 8 pages!). Don't open any more threads on the subject. Other than learning the math involved, I don't know any other approach that will help. I just know discussion about it has failed.

 

Thread closed.