Speed of light question.?

Question

I know that it is not possible to exceed the speed of light relative to another object. However, I cant help but think, given the vastness of the universe that we are moving at the speed of light relative to 'something' in the universe (be it an atom, a star, etc.).

Is this a rational thought? It sounds like a stupid question to even me, the asker! Im sure that there is a simple answer, though I supose I am wrong, but why?

An answer such as "no mass can move at c m/s" will not do as an explanation.

Answer 1

It's a very good question.

Ready for this one though?

If you were standing at the center of the universe you would see the left side moving away from you at the speed of light and the right side would be moving away from you in the opposite direction also at the speed of light.

So obviously the difference in speed is 2 times the speed of light, right?

(Here's the good part)

Wrong, if you were riding a light wave at the edge of the universe and you looked across at the other edge, it would only be moving away from you at the speed of light not twice it as you may have suspected.

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ANSWER TO YOUR QUESTION BELOW:
All that aside, it is not possible that we are moving from anything at the speed of light. At least not when you use the Lorentz invariant formula for the addition of velocities. The reasoning behind this has to do with inertial references frames.

In the simple case of velocity additions that we use for every day purpose it is just V1+V2=V3, but for relativistic speeds it is V3,1=(V1+V2)/(1+(V1*V2)/C^2)

That is to say, the speed at which the two objects seperate with respect to the first object V3,1 is equal to the sum of the velocities divided by 1 plus the ratio of the product of the objects' velocities with the square of the speed of light.

The reason we use this Lorentz invariant form is more complicatred but suffice it to say the math of everything works out a lot better.

Though it is true that scientist have forced the group velocity of light to travel several time faster than C, the wave front velocity has never breached C itself. This is why physics questions should only be answered by physicists.

Answer 2

It's a nice thought, and while it makes sense that if nothing can move faster than the speed of light, maybe two objects, both travelling toward each other at 0.6 c (or 60% of the speed of light) as observed by some outside third point of view, they can be said to be moving towards each other with a combined speed of 1.2 c.... except for two things:

1) Relativity states that your sensation or measurement of motion is, indeed, relative, dependant on your frame of reference. So you can't move toward another object faster than the speed of light, because relativistic effects would prevent it.

2) More practically, there's not much out there in our experience which travels at even a significant fraction of the speed of light (okay, sure, whole galaxies travel at millions of miles an hour... away from us) At least on our scale, in our little local area, nothing travels that fast, so the experiment could never really be conducted.

I'm sure there are others with a bit more physics background who might be able to shed a little more light on why this is so...

Answer 3

Only photons move with speed of light relative to us. May be some other massless particles too. Everything else is slower. Vastness of space has no relevance here. Chose any object (as far from us as you wish) and consider Earth and that object.

There is no theory that would reasonably allow moving faster than light and without internal contradictions. And there is no single observation of anything moving faster than light. This does not leave much to say.

Answer 4

Well, it sounds simple, and I'm no physicist, but I think relative to a photon, we are traveling the speed of light all the time. The problem with that analogy is that the reference and the measurement belong to the same object, which is invalid.

However, the edge of the universe is moving at the speed of light. Then again, we're getting into the electromagnetic spectrum again. Oops!

Answer 5

I would not call it a "stupid" question; it is just a common misunderstanding of the principles of the theory of relativity.
When dealing with relativistic velocities (velocities close to the speed of light), one cannot simply add velocities together as one can in Galilean relativity.

For example (all speeds measured with respect to the ground unless otherwise stated),
If you are in a car moving at 70 mph in one direction and you throw a ball in the opposite direction of motion at 40 mph, then to you in the car, the ball looks like it is traveling at 110 mph away from you.
Now if instead of 10 mph, you were traveling at 70% of the speed of light and you threw the ball at 40% of the speed of light...to you in the car, the ball would NOT look to be going faster than light....it would still be going some percentage slower than c.

No matter the reference point, nothing with mass can ever travel at, or faster than, the speed of light.

Take another example,
There are three planets lined up...we will call the middle planet "Earth" for convenience, and the other two planets, "A" and "B".
If planet "A" is moving away from Earth at 60% of the speed of light in one direction and planet "B" was moving away from Earth at 60% of the speed of light in the other direction, neither planet as seen from Earth is exceeding the speed of light, that is plain to see. But what is not so plain to see is that any observer on either planet "A" or "B" looking at the other two planets would still not see the others moving faster than light either.

To add relativistic speeds,
u’ = (v- u) / (1 – uv/c^2)
Where u, v, u’, and v’ are velocities as measured from different reference frames of the two objects and c is the speed of light in a vacuum.
In order to solve these questions, you need to decide just what frame of reference you want to use and what you want to call it since there are no “absolute” speeds or positions in the universe; it is all relative to the observer.
http://math.ucr.edu/home/baez/physics/Relativity/SR/velocity.htm

Answer 6

Yes. There are.
"Faster-than-light" observations and experiments

It has long been known theoretically that it is possible for the "group velocity" of light to exceed c. One recent experiment made the group velocity of laser beams travel for extremely short distances through caesium atoms at 300 times c. However, it is not possible to use this technique to transfer information faster than c: the velocity of information transfer depends on the front velocity (the speed at which the first rise of a pulse above zero moves forward) and the product of the group velocity and the front velocity is equal to the square of the normal speed of light in the material.

Answer 7

Whether one is moving toward a beam of light or away from a beam of light and whether you are moving very slowly toward the beam or as fast as the speed of light, the measurement of speed of light yields the same value.

This is the theory of relativity and is supported by much experimental verification like Michelson- Morley experiment.

Keeping this in mind, let us imagine that we are moving with the speed, little less than the speed of light, say 0.9999C, with respect to some fixed star.

We measure the speed of light - whether the light is coming toward us or away from us -while we are moving with the speed of light.

Our measurement must yield the same value as if we were not moving.

How is it possible?

The length of the meter scale will reduce to 0.14 times its original length when we go with such a speed.
The time will be slowed to 0.14 times its original value.

As the length and time are reduced by the same factor, we will measure the speed of light as C, the value which we measured when we were at rest.

If we move exactly with the speed of light again we will have to measure the speed of light as C. But this time the length has become zero and time is also zero. How to measure the speed of light with no length and no time?

This is the reason that one says that material objects cannot move with the speed of light.


But no one can prevent one’s imagination of moving with speed of light ignoring other factors.

If any theory claims that objects can move faster than light then it must explain why meaurements of speed of light yields the same value irrespective of its speed.

Answer 8

I do believe that there is no real proof that says nothing moves faster the the speed of light.
So far observation indicate that the Universe expands faster then the speed of light.
Note the theory of autodynamics indicates that gravity causing particles are moving faster than light.
so I am in the same boat as you are =who do we believe what are the tests?Most of us just repeat what we are told about Einstein's relativity but many of
its proof are not quite a propos and do not relate to the possibility that there could exit entites that move much faster than the speed of light.

Answer 9

Maybe if you were moving at 1/2 the speed of light left and something else were moving at 1/2 the speed of light right, the relative speed each of you would have receding from each other would be the speed of light.

However, other than photons, quarks, gravitons, and various other electromagnetic phenomena, I don't know of anything moving anywhere close to .5c.

And it would take a prohibitive amount of fuel to get up to even 1/2 lightspeed.

Answer 10

solid adequate. Time does now no longer circulate slower for speedy products. evidently to you, assuming you ought to be table sure, that factor is passing slower for speedy products. If there are not any accelerations reward - each thing is continuously shifting on the equivalent speeds relative to one yet another - then there is not any thank you to tell who's moving and who's at rest. Now the twin paradox, which you form of paraphrased right here, has 3 accelerations in it. you start up from entertainment and accomplish an exceedingly extreme speed. After a time, you turn around this suggests which you sluggish down, you momentarily stop, and you speed as much as a extreme speed back. for this reason you attain earth and sluggish to a stop. At each acceleration, you adventure a stress which the earthbound individual does not so it is clean who's in circulate and who's at rest. subsequently, you are going to return after 10 years a while superior to seek for out that a plenty longer time has exceeded on the planet. Now celebrity trek assumes there is the thank you to adventure exterior of the 4 dimensional area that defines the universe - the so-usual as subspace. in this subspace, relativity does not persist with - that's exterior the universe rather plenty - so which you ought to circulate from factor to element in a finite quantity of time and, the time it takes to traverse the hollow as measured via the starship's clock stands out as the time that elapses in the universe - style of no longer likely even nonetheless crucial in case you're writting one hour long television episodes. there is not any evidence for the fashion of holiday use in widespread individual trek.