why can nothing go faster than the speed of light?

Question

i understand Einsteins theory of relativity, how its impossible to travel faster than light because the energy used is leading up to infinity, but why is it that 2 objects traveling towards each other at the speed of light only pass at the speed of light rather than twice the speed of light?

Answer 1

When viewed from an independent frame of reference, two objects can appear to be closing their distance at faster than the speed of light. This is especially true for jets from quasars at the centers of other galaxies:

http://www.stsci.edu/ftp/science/m87/press.txt

"The term `superluminal motion' is something of a misnomer. While it accurately describes the speeds measured, scientists still believe the actual speed falls just below the speed of light."

There was also some work done with lasers in cesium chambers that produced an apparent paradox, but on further investigation this was explained within Einstein's framework as well:

http://www.discover.com/web-exclusives-archive/score-another-win-for-einstein1106/

Answer 2

Einstein's Theory of Relativity says that you cannot ACCELERATE something to the speed of light because the energy required would approach infinity because the mass of the object would approach infinity.

Thus far there is nothing that says that "things" cannot go faster than the speed of light if they're already travelling at the speed of light - ie photons.

If you look at the math, once you pass beyond light speed, the energy required for further acceleration might actually ~decrease~.

Answer 3

When the speed of an object is increased the value of 1m length and 1 second time changes as follows.

V: speed, L: length and T: time.
C is the speed of light in vacuum.
When V = 0.5 C, L =0.8666 m and t = 0.8666 s
When V = 0.6 C, L =0.8m and t = 0.8 s
When V = 0.7 C, L =0.71 m and t = 0. 71 s
When V = 0.8 C, L =0.6 m and t = 0. 6 s
When V = 0.9 C, L =0.0.435 m and t = 0.0.435 s
When V = 0.95 C, L =0.31225 m and t = 0.31225 s
When V = 0.99 C, L =0.141 m and t = 0.141 s
When V = 0.999 C, L =0.04471 m and t = 0.0.04471 s
When V = 0.9999 C, L =0.014141 m and t = 0.014141 s
When V = 0.99999 C, L =0.00447 m and t = 0.00447 s
When V = 0.999999 C, L =0.00141 m and t = 0.00141s
When V = 1 C, L =0m and t = 0s
L= 0 and t=0 is meaning less and hence any object cannot move with a speed equal to C.
When V> C , L and T becomes imaginary which is also not possible.

Answer 4

Read tattie_he--the operative phrase is "..as far as we know." (Why you got a thumbs down on this great question is something on which I won't even speculate.) I don't agree that it's impossible to travel faster than light, & I won't give any brilliant reasons. "Infinity" is also a key word here. Who can comprehend it? Not even Einstein. What a fantastic mind journey we could take, "speculating." Would we go "back" to the past? How would this impact the concept that only the present is reality? So many dimensions. I watched two incredible thingees on CSpan, about the string theory. (I find physicists the most fascinating--open-minded.) A great experience for the little grey cells that aren't operating on full capacity. That's why I love people with extrasensory perception. Shoot. Once it was TOTALLY accepted that the earth was flat, (as an example). Who KNOWS? Tomorrow & tomorrow creep in this petty pace..so very nice to "run across" a good question. Now let's look at the answers! I betcha I know.......

Answer 5

Say a car going 10 mph hits another head on going 20 mph the resulting crash is from a 30 mph collision right? wrong! Einstein proved that even things at slow speeds don't add up in the way we see them everything is reletive to the speed of light the only true constant. This is what Einstein beleived and was the guiding principal in his theories. He wrote another theory proving that nothing can exceed the speed of light if you wish to understand perhaps you should look that theory up. Regardless nothing can be accelerated to the speed of light since its mass would be come infinite and technically speaking it would become light. To add to the confusion if we could travel faster than the speed of light we would actually be going so fast that we would begin traveling back in time an interesting thought to say the least. Anyway Einstein was indeed ahead of his time and all I can say is that you attempt to locate his theory on why things can't move faster than the speed of light.

Answer 6

Tachyons travel no less than the speed of light. There may well be a whole family of hyper light particles.

If you want to understand the interaction of intersecting photons you will need to take into account the particle mass and it's effect on the time/distance relation. Since mass affects time, consider how the interacting mass changes the relative experience of the photons.

I hope this helped. Good Luck!

Answer 7

The concept of nothing going faster than the speed of light was a conclusion backed in to. No one knows exactly why.

Einstein could tell that these light beams that should speed up did not. This let him to see that the closer you get to the speed of light the slower time became. This led him to how anything going faster than the speed of light would go through infinite mass.

As to why light, it has not been definitively proved.

Answer 8

Avatar:-
A little knowledge is, Dangerous!
Two objects travelling at the speed of light, pass each other at the speed of light.
One object looking at the second object, has the RELATIVE perception of travelling at twice the speed of light.
Nothing can travel faster than the speed of light, as far as we know!

Answer 9

If one were able to move information or matter from one point to another faster than light, then according to special relativity, there would be some inertial frame of reference in which the signal or object was moving backwards in time. This is a consequence of the relativity of simultaneity in special relativity, which says that in some cases different reference frames will disagree on whether two events at different locations happened "at the same time" or not, and they can also disagree on the order of the two events (technically, these disagreements occur when spacetime interval between the events is 'space-like', meaning that neither event lies in the future light cone of the other).[7] If one of the two events represents the sending of a signal from one location and the second event represents the reception of the same signal at another location, then as long as the signal is moving at the speed of light or slower, the mathematics of simultaneity ensures that all reference frames agree that the transmission-event happened before the reception-event.[7] However, in the case of a hypothetical signal moving faster than light, there would always be some frames in which the signal was received before it was sent, so that the signal could be said to have moved backwards in time. And since one of the two fundamental postulates of special relativity says that the laws of physics should work the same way in every inertial frame, then if it is possible for signals to move backwards in time in any one frame, it must be possible in all frames. This means that if observer A sends a signal to observer B which moves FTL in A's frame but backwards in time in B's frame, and then B sends a reply which moves FTL in B's frame but backwards in time in A's frame, it could work out that A receives the reply before sending the original signal, a clear violation of causality in every frame. An illustration of such a scenario using spacetime diagrams can be found here.

It should be noted that according to relativity it would take an infinite amount of energy to accelerate a slower-than-light object to faster-than-light speeds, and although relativity does not forbid the theoretical possibility of tachyons which move faster than light at all times, when analyzed using quantum field theory it seems that it would not actually be possible to use them to transmit information faster than light[8], and there is no evidence for their existence.

Answer 10

Because they are moving towards each other, one is traveling to the other, both going the speed of light. It is like two cars, one car is going 65 miles towards the other car, while the other car is also going 65. In this case light is moving three times ten to the eighth power meters seconds, and the other light the same.