When Einstein discovered relativity, did he already know that C was the same for any observer, moving or not moving? If not, would it have been possible to discover relativity without this information? I understand why time dilation could be the only explanation for a constant C, but why exactly is C constant? It has been proven, but has anyone ever explained WHY exactly C is the same for any observer? Time dilation, yes, but then why is there time dilation in the first place?

eh heh. too many questions on that last post. I guess I am just looking for an answer to this one: Why is C the same for any observer, and if the answer is time dilation, why is there time dilation?

constant c is not proved by relativity, it is an axiom of relativity based on sound logical, physical and mathematical arguements. Also constant c is predicted from maxwells equations.

Here's what Einstein did:

1. Assume c is constant for all observers.
2. Work out the theoretical consequences (e.g. time dilation is one consequence of this assumption).
3. Check to see if experiment matches the predicted consequences. (It does.)

But am I correct in assuming that the theory of relativity was based around explaining how C could be constant? (i.e. Einstein reasoned that if C was constant both from a moving observer and from a stationary one, then they must be experiencing length contraction and time dilation)

No you are not correct Reinstein. Einstein did not prove c to be constant, he assumed c to be constant and derived the equations from this starting point.

By the way, it is an assumption which entirely agrees with nature.:)

ryans,

In your earlier post when you said I was incorrect, i think you misunderstood because your statement immediately after that was actually what i ment. I know Einstein didn't discover that c was constant, I was asking if this was sort of like the one thing that made Einstein say 'hum, something unexplained is going on here, i wonder if i can figure it out.'

But i still don't feel that my original question has been answered. Yes, there have been experiments to verify a constant c and i don't disagree their validity, but I am asking WHY. Can anyone tell me WHY C is constant and WHY time slows down?

Originally posted by Reinstein
ryans,

In your earlier post when you said I was incorrect, i think you misunderstood because your statement immediately after that was actually what i ment. I know Einstein didn't discover that c was constant, I was asking if this was sort of like the one thing that made Einstein say 'hum, something unexplained is going on here, i wonder if i can figure it out.'

But i still don't feel that my original question has been answered. Yes, there have been experiments to verify a constant c and i don't disagree their validity, but I am asking WHY. Can anyone tell me WHY C is constant and WHY time slows down?

there is a perfectly good explanation for why c is the same for any observer.

what is c? the speed of light.

what is light? electromagnetic radiation.

how do we describe electromagnetic radiation? with maxwell s equations.

now look at maxwell s equations. they need to be valid in any reference frame. and they are unambiguous about the speed. it is c. in any reference frame. that s what einstein was the first to realize.

now what about time dilation? well if you want to measure the speed of light the same in any reference frame, no matter how fast you re moving, time dilation must occur, to keep everything consistent. same with length contraction.

Has time dilation been observed? If so, what was the experiment?

Time dilation is observed all the time in particle accelerators. Particles at rest decay faster than particles which are moving. This has also been observed in muons entering the Earth's atmosphere and in experiments performed with very accurate atomic clocks.

Reinstein,

I would respond to your post again, but I guess it would just be deleted again. Anyway, good luck in trying to understand relativity....

Tom:

Your previous reply was not deleted. The thread was split, according to the "Alternative theories policy" (see the relevant thread, which is sticky).

Your post can be found in the "C - alternative explanations" thread.

JamesR.,

Good show. I too thought censorship had occured.

James,

Your previous reply was not deleted. The thread was split, according to the "Alternative theories policy" (see the relevant thread, which is sticky).

It makes no difference whether my post was deleted or moved. I was responding to Reinstein regarding his/her post. If I couldn't find my post after you moved it, I'm pretty sure that Reinstein didn't find it either. So unless you believe that I was talking to myself, typing my response to Reinstein's post was just a waste of my time.

Tom

James R.,

Tom has a point. I think you should enter a note when posts are moved so that others could puruse the matter at their choosing.

Originally posted by Prosoothus
James,



It makes no difference whether my post was deleted or moved. I was responding to Reinstein regarding his/her post. If I couldn't find my post after you moved it, I'm pretty sure that Reinstein didn't find it either. So unless you believe that I was talking to myself, typing my response to Reinstein's post was just a waste of my time.

Tom

prosoothus, the original poster asked for an explanation of why c is constant, not for experimental evidence of it. the fact is, the michaelson-morley experiment, whether it was null or not, does not say anything about why the speed of light should be constant.

your post was off-topic, and clearly intended to engulf the thread into another debate of crackpot stature.

look, if you have issues with site policy, take them to the site policy forum. in this thread, it is off-topic. this is a physics/math forum, remember?

It is a fair point that I should have left a note in the thread saying that it had been split. In future I will do that.

lethe,

your post was off-topic, and clearly intended to engulf the thread into another debate of crackpot stature.

You're wrong. My post was not off-topic. Look at one of Reinstein's questions:

It has been proven, but has anyone ever explained WHY exactly C is the same for any observer?

Reinstein made an incorrect assumption that it has been proven that the speed of light is constant for all observers, while experiments show that the speed of light is close to c for stationairy observers on the surface of the Earth. Even though my post didn't answer his question, I tried to point out that his assumption may not be true.

For example, if I asked "Why are neutrons made of two quarks?", would you try to explain to me why neutrons are made of two quarks, or would you tell me that neutrons are made out of three quarks? If you did tell me that neutrons are made of three quarks, would your reply be off-topic since that wasn't the question I was asking?

Tom

James,

It is a fair point that I should have left a note in the thread saying that it had been split. In future I will do that.

OK. Thanks.