Relativity Paradox: Is Moving at Speed of Light Possible?

In summary: If there's a light source/emitter/whatever, and you're moving towards or away from it, then you will see the light source as moving faster than you are... but if you're stationary, then the light will appear to be moving at the same speed as you.
  • #1
jaydnul
558
15
Well its a paradox to me haha. If light has a maximum speed but yet every one object in the universe is moving relative to another... 1. Wouldnt I technically be moving at the speed of light since the light emitted from my iphone are zooming past me at 300,000,000 m/s?

2. If no, then there has to be a way to have absolutely no directional motion in space, right? (Not on Earth of course)
 
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  • #2
you can't assume light ray to be stable...
since it is the basis of relativity that a photon moves wid the velocity which is actually 299792458 m/s irrespective of the speed of the observer...

reply ur comments
 
  • #3
lundyjb said:
Wouldnt I technically be moving at the speed of light since the light emitted from my iphone are zooming past me at 300,000,000 m/s?

No, because you cannot use light as a reference frame for measuring other velocities. When we say something like "A's reference frame" or "relative to A" we mean the reference frame in which A is stationary. Light travels at speed c in all inertial reference frames, so there is no frame in which light is stationary. Therefore we cannot speak of velocities "relative to light."
 
  • #4
Wow, so if you were moving at say, 200,000,000 m/s, then a photon would appear to be moving 300,000,000 FASTER than you are?
 
  • #5
lundyjb said:
If light has a maximum speed but yet every one object in the universe is moving relative to another... 1. Wouldnt I technically be moving at the speed of light since the light emitted from my iphone are zooming past me at 300,000,000 m/s?

2. If no, then there has to be a way to have absolutely no directional motion in space, right? (Not on Earth of course)

1) When we say that speed is always relative to something, that's a short way of saying that we can pick a frame of reference in which the speed of an object is zero, or any other speed we please. Use the ground as the frame of reference, and the car is moving past at 60 mph; choose the car and we'd say it was at rest while the road and the scenery were moving backwards at 60mph; meantime the guy watching from Mars and considering himself at rest says that the earth, the road, the car are all moving at a few miles a second relative to him.

But (many threads over in the relativity sub forum - search for "rest frame of a photon") light moves at speed c in all frames; there is no frame in which light is at rest or even moving at any other speed than c.

Therefore, you can say that the light from your iPhone is moving at c relative to you, but you cannot say that from the point of the light, it is at rest and you're moving relative to it. Light doesn't have a rest frame or "point of view".

2) No, that is not right. It would be right if we could find a frame in which the light was at rest... But we can't.

[Edit: Looks like I don't type fast enough, or I type too much :smile: Jtbell said the same thing while I was still keying in my response. Silly iPad :smile;]
 
  • #6
lundyjb said:
Wow, so if you were moving at say, 200,000,000 m/s, then a photon would appear to be moving 300,000,000 FASTER than you are?
Not really.

If you were traveling at 200,000,000 m/s with respect to some reference frame, a photon would still travel at 300,000,000 m/s with respect to that frame. (And it will also travel at that speed with respect to your frame, in which you are at rest.)
 
  • #7
lundyjb said:
Wow, so if you were moving at say, 200,000,000 m/s, then a photon would appear to be moving 300,000,000 FASTER than you are?

200,000,000 m/s relative to WHAT?

But the answer to your question, after we make it more precise, is "yes".
Try this: two spaceships are flying in the same direction through empty space. They are moving at 200,000 m/s relative to each other. Both will measure the speed of a passing flash of light to be c. Yes, that merits a "wow", and you will also want to google for "relativistic velocity addition" or look for the many threads on this topic in the relativity forum.
 
  • #8
lundyjb said:
Wow, so if you were moving at say, 200,000,000 m/s, then a photon would appear to be moving 300,000,000 FASTER than you are?
What do you mean by "appear"? How do you plan to watch a photon?
 
  • #9
ghwellsjr said:
What do you mean by "appear"? How do you plan to watch a photon?

As funny as that is, it's a great point / question...at any speed.
 

FAQ: Relativity Paradox: Is Moving at Speed of Light Possible?

What is the Relativity Paradox?

The Relativity Paradox refers to the concept in Einstein's theory of relativity where time and space are relative and can be affected by an object's velocity. It raises the question of whether it is possible for an object to travel at the speed of light, as it would result in time dilation and other paradoxical effects.

Is it possible to move at the speed of light?

According to Einstein's theory of relativity, it is not possible for an object with mass to travel at the speed of light. As an object approaches the speed of light, its mass increases infinitely and would require an infinite amount of energy to accelerate further. Therefore, it is impossible for an object to move at the speed of light.

What is time dilation?

Time dilation is a phenomenon predicted by Einstein's theory of relativity where time appears to pass slower for an object in motion relative to an observer. As an object's velocity increases, time for that object appears to slow down. This is due to the fact that the speed of light is constant for all observers, and as an object's velocity approaches the speed of light, time for that object slows down relative to an observer at rest.

How does the Relativity Paradox affect space travel?

The Relativity Paradox has significant implications for space travel. As an object approaches the speed of light, time for that object slows down, which means it would take longer for an astronaut to age compared to someone on Earth. This could potentially lead to scenarios where an astronaut travels for a short period of time but returns to Earth to find that much more time has passed.

Is the Relativity Paradox proven by experiments?

Yes, the Relativity Paradox has been proven through numerous experiments, including the famous Hafele-Keating experiment and the Michelson-Morley experiment. These experiments have shown that time dilation and other effects predicted by Einstein's theory of relativity do occur in the real world, providing evidence for the validity of the theory.

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