# Evidence for infinites at light speed.

1. Jul 23, 2009

### Researcher X

What evidence is there that at light speed things such as time dilation, and mass/energy, actually reach infinity?

2. Jul 23, 2009

### mathman

There is plenty of evidence that the Lorentz transformations are valid. However it is impossible to reach the speed of light, so reaching infinity is impossible.

3. Jul 23, 2009

### Pengwuino

To add to that, infinity is not something that can be reached, it is undefined. A seemingly popular example of time dilation is how GPS satellites must compensate for time dilation (using a 3rd or 4th satellite) due to the precise calculations that must be made to determine your position on Earth. There's also a popular high energy physics example I can't quite remember but it has to do with the fact that a certain particle's decay is so quick that it can't be detected unless you speed the particle up enough so that the decay takes long enough in our reference frame that it can be detected. I can't remember the specifics though.

4. Jul 23, 2009

### Researcher X

Maybe I'm misreading it, but it's a paradox to think of something moving at the speed of light, because of time dilation curving to infinity.

If it takes you 2 seconds from your reference frame to take a journey encompassing several years from another, that's all well and good, but when it stops being fractions of the speed of light, and you "reach" the infinity point, all journey times from that frame become zero, which is a paradox, because a time period of zero can't even take place at all, and in the frame outside of the hypothetical transport, an infinite amount of time has occurred! You might as well have arrived before you took off for all the sense that makes.

Is it not possible that the speed of light actually makes this effect just ridiculously large instead of infinite?

5. Jul 23, 2009

### Staff: Mentor

No, it isn't. Particle accelerators have tested the theory to an extremely high energy, getting extremely close to C. The equation holds.

6. Jul 23, 2009

### Staff: Mentor

Sure, but all experimental data so far has fit curves which go off to infinity as v --> c. We go by the data that we have in hand. If someone finds something different, then theorists will go off and look for a new theory that either modifies or fundamentally replaces relativity.

There are actually physicists who are working on replacements for current relativity theory, but those theories are pretty much speculative right now, for lack of experimental data.

7. Jul 23, 2009

### Staff: Mentor

Yes, although I would use the word "nonsense" or "non-physical" rather than "paradox".

that is why it is nonsense. You cannot "reach the infinity point". It is not even a point, let alone a reachable one.

What this infinity means is that there is no finite amount of energy which will accelerate a particle to c. So far, we have never found an exception.

8. Jul 23, 2009

### markonline

the faster that one travels the more force is need to travel faster, if one is traveling at .99c time is 7x slower therefore he must have 7x more force to accelerate, as this number goes up and up it will take more and more effot to reach c making it impossible.

9. Jul 23, 2009

### Phrak

Which sort of infinity are you talking about? Is 1/0 infinity, or undefined? Is 1/0=2/0 ?

10. Jul 24, 2009

### HallsofIvy

Staff Emeritus
Yes, which means that it can't happen. Far from being "evidence is there that at light speed things such as time dilation, and mass/energy, actually reach infinity" What you just quoted means it can't happen. The can't be "evidence" of something that can't happen! There is, on the other hand, plenty of evidence for time dilation, mass increase, etc. for objects moving at a very high relative speed.

11. Jul 25, 2009

### Rebel

I see more probable that theorists would look at this supossed new findings and study what is wrong with the experiment.

12. Jul 25, 2009

### Staff: Mentor

Huh?

13. Jul 26, 2009

### HallsofIvy

Staff Emeritus
There have been experiments with "mass increase" or "time slowing" with very fast particles that have verified the formulas of relativity. But, of course, there can't be any experiments that show the "the mass of a particle moving at light speed is infinity" and relativity doesn't say that it would be. Relativity says that a particle's "mass" increases without bound as its speed approaches that of light.

14. Jul 26, 2009

### HallsofIvy

Staff Emeritus
I don't know why so many people think scientist have some kind of "stake" in maintaining a theory. A scientist would become far more famous by verifying something that violates relativity than by finding an error in the experiment. Scientist are always hoping for anomalous results!

15. Jul 26, 2009

### Staff: Mentor

Actually, I would say that it's not an "either-or" situation. In general, theorists will take both approaches, some doing one, some doing the other, some doing both. After the first experiment comes along with these "new findings," most of the emphasis will be on analyzing the experiment and looking for flaws. If more experiments come along with similar results (preferably using different techniques!), emphasis will shift towards re-evaluating, modifying, and/or replacing the theory.

16. Jul 26, 2009

### Rebel

Of course, I just pointed out the position respect to the overwhelming experimental support for relativity.

17. Jul 26, 2009

### Staff: Mentor

Right, the initial mix of emphasis on checking the experiment versus modifying the theory depends on how solidly established the theory is, based on previous experiments. Also, I expect, on whether the "new findings" are in an area (of energy / velocity / whatever) that has previously been tested, or well outside a previously-tested area, or what.

18. Jul 26, 2009

### markonline

ok...

lets say that time dialation increases as an exponential rate as velocity increases. now to reach the speed of light, time dialation must equal infinite. while infinity may not be a real number a possible very very large number that goes on forever could take its place

19. Jul 26, 2009

### DaveC426913

What is the point in this line of thought? Is there some reason you find our current understanding of the universe to be too consistent for your liking?

We have a theory, we have a formula and we have a preponderance of evidence that points to a very consistent universe in the context of SR, where all the puzzle pieces fit together beautifully. Is there some reason why you think that it should be only mostly consistent? Why you think a single puzzle piece should have a tab that sticks out like a flap of dead skin?

20. Jul 26, 2009

### markonline

to my liking, hmm. the question being what is the evidence of infinite. that was my answer. and yes i believe it to be consistently inconsistent. why don't you just put everything on the forum about SR. and you can just leave it at that.