# Why is there a universal speed limit, c, and why is it what it is?

by CosmicVoyager
Tags: limit, speed, universal
 P: 134 AS ONE APPROACHES 'c' THE MASS OF GIVEN PARTICLE START'S INCREASING, GIVEN BY: M=Mrest/(sqrt(1-(v2/c2))) SO AS ONE APPROACHES c, v2/c2 INCREASES & WILL TEND M TO INFINITY.SO THIS IS THE SIMPLEST REASON WHY ONE CANNOT MATCH 'c' WITHOUT HAVING INFINITE ENERGY(WHICH IS NOT POSSIBLE).PARTICLE ACCELERATOR'S HAVE GONE TO "0.99c" (WITH SMALL PARTICLES LIKE ELECTRON) BUT NOT 'c'.
P: 70
 Quote by 1994Bhaskar AS ONE APPROACHES 'c' THE MASS OF GIVEN PARTICLE START'S INCREASING, GIVEN BY: M=Mrest/(sqrt(1-(v2/c2))) SO AS ONE APPROACHES c, v2/c2 INCREASES & WILL TEND M TO INFINITY.SO THIS IS THE SIMPLEST REASON WHY ONE CANNOT MATCH 'c' WITHOUT HAVING INFINITE ENERGY(WHICH IS NOT POSSIBLE).PARTICLE ACCELERATOR'S HAVE GONE TO "0.99c" (WITH SMALL PARTICLES LIKE ELECTRON) BUT NOT 'c'.
We all undrestand this, the problem is that the formula you have used is a result of the postulate that c is the speed limit. The question was: why the speed limit is c ? and you shouldn't try to answer it by using the fact that c is the speed limit...
 P: 134 THANKS atomthick. I think einstein did all this just to back michelson-morley experimental data.Only EXPERIMENTS can give evidence concerning true properties of space & time.Maybe we should not break our head on an experimental fact.It's just like to think that why gravitation is ATTRACTIVE & not REPULSIVE!!
 Mentor P: 17,526 Bhaskar, please turn off all caps. It is considered "shouting".
 P: 134 so sorry about that.I'm quite new to this forum.
 Mentor P: 17,526 No worries, thanks for going back and editing. I was not expecting you to do that, but that is especially considerate!
 P: 28 Some may find this link interesting - http://www.phys.unsw.edu.au/einstein...well.htm#light Take this brother and may it serve you well, Q
 P: 1 Hi all, On the moment i'm learning about special relativity in College and there is a fairly good explanation for the cosmic speed limit, indeed caused by causality (which comes from second law of thermodynamics). I included 3 photo copies of my textbook that explain the relevant part. After reading i think you will understand why nothing can travel faster than the speed of light, and so why it is the cosmic speed limit. On the other hand there is one thing i don't understand, and that is why we would not be able to travel at the speed of light, since the book tells we can only travel at near the speed of light and only information can travel at the speed of light. But on the otherhand it says that we could be the information. If somebody understand out of this text why we cannot travel at the speed of light, please post. The page come from Six ideas that shaped physics Unit R by T.A. moore Very good step by step explanation of special relativity. happy reading, Thanks. Attached Thumbnails
P: 3,188
 Quote by zyap Hi all, On the moment i'm learning about special relativity in College and there is a fairly good explanation for the cosmic speed limit, indeed caused by causality (which comes from second law of thermodynamics). I included 3 photo copies of my textbook that explain the relevant part. After reading i think you will understand why nothing can travel faster than the speed of light, and so why it is the cosmic speed limit. On the other hand there is one thing i don't understand, and that is why we would not be able to travel at the speed of light, since the book tells we can only travel at near the speed of light and only information can travel at the speed of light. But on the otherhand it says that we could be the information. If somebody understand out of this text why we cannot travel at the speed of light, please post. The page come from Six ideas that shaped physics Unit R by T.A. moore Very good step by step explanation of special relativity. happy reading, Thanks.
Thanks, it's a nice text; but as you already discovered, one weakness is that it fails to explain why we cannot travel at the speed of light. For that you need to look at other, more physical explanations - and probably that has already been done earlier in this thread.

Harald
 P: 108 Light is Electromagnetic so if light travels at diffrent speeds in different frames then Laws of Electromagnetism will also vary giving different results in different frames..but thats not possible so c is constant!!
Math
Emeritus
Thanks
PF Gold
P: 39,682
 Quote by sahil_time Light is Electromagnetic so if light travels at diffrent speeds in different frames then Laws of Electromagnetism will also vary giving different results in different frames..but thats not possible so c is constant!!
Okay, so no explain why it is trivial (more obvious than the fact that c is constant) that the Laws of Electromagnetism can NOT give different results in different frames.
P: 848
 Quote by sahil_time Light is Electromagnetic so if light travels at diffrent speeds in different frames then Laws of Electromagnetism will also vary giving different results in different frames..but thats not possible so c is constant!!
sahil_time, why is that not possible?
P: 108
 Quote by bobc2 sahil_time, why is that not possible?
Because doing so may change the whole concept of Forces!!Like if C was different for different observers then epsilon/permeability would be different and hence the electric field and magnetic pheneomenon would be different for different observers!!Like Electric field at a point could have infinite possible values!!
Well thats what i think!!

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