Travelling (at) the speed of light away from a lightsource

In summary, the question is asking what would happen if there was no frame moving at the same speed as the photons leaving the frame. If the photons are massless and have no mass, then they would still leave the frame at the same speed, which would be the same as the speed of light. However, if the photons have mass, then they would slow down as they traveled away from the screen.
  • #1
lolcopters
3
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Hi all,
I was trying to figure out the following:
Say I am standing right in front of a movie playing on a screen. Then, at time t0, I immediately am traveling at the speed of light away from this non-moving screen. Say I looked back while traveling away. Would I see an image (the frame the screen was showing at t0), or would I see a movie, because the speed of light is constant in all frames?

Also, to those who alter the question to "you can't travel at c, now say you were traveling at .99c...", then assume I'm massless, and have working massless eyes, and am traveling at c
 
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  • #2
lolcopters said:
Also, to those who alter the question to "you can't travel at c, now say you were traveling at .99c...", then assume I'm massless, and have working massless eyes, and am traveling at c
You cannot get around physics by wishing and assuming that it worked differently. You either want an answer to a well defined question within the current working theory or you want a fairy tale.
 
  • #3
Asking what would happen in circumstances that are not physically possible is a bit of a risk, but I'll have a go at it.
You propose traveling away from the screen at the same velocity as photons are traveling away from it.
Thus if you had any way to observe the photons (which you won't) you would see a still frame picture of what was on the screen at the time of your departure
 
  • #4
This is an example of proof by contradiction (reductio ad absurdum).

Assumption: there is such a thing as a massless eye moving at ##c##.

Conclusion: As seen by the eye, the movie would be frozen and the movie would not be frozen.

The conclusion cannot be true; it contradicts itself. Therefore the assumption must be false.
 
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Likes rootone
  • #5
I guess what I was trying to get at was: would the result of it being a movie/picture be affected by the fact that the speed of light is constant in all frames? Say that there is no eye. There is just light from the screen traveling through space. From a reference frame moving at speed of light c away from the screen, is it a movie, because c is constant, or is it a picture, because the frame is traveling at the same speed as the light leaving the frame?
I know it's non-physical, but I asked this question because I want to better understand the implications that c is constant in all frames.
 
  • #7
lolcopters said:
I know it's non-physical, but I asked this question because I want to better understand the implications that c is constant in all frames.
If you know it is non-physical, why do you ask the question in a physics forum? There is no reference frame moving at the speed of light! In fact, no reference frame can be said to have a particular velocity unless it is in relation to another reference frame.

With PAllen's post, I am going to close this thread as it is not going any further.
 

FAQ: Travelling (at) the speed of light away from a lightsource

How fast is the speed of light?

The speed of light in a vacuum is approximately 299,792,458 meters per second. This is often denoted as "c" in scientific equations.

Can anything travel at the speed of light?

According to the theory of relativity, nothing with mass can travel at the speed of light. Only massless particles, such as photons, can reach the speed of light.

What happens to time when travelling at the speed of light?

According to the theory of relativity, time slows down for objects travelling at the speed of light. This means that time passes slower for an object moving at the speed of light compared to an object at rest.

Is it possible to physically travel at the speed of light?

Based on our current understanding of physics, it is not possible for an object with mass to reach the speed of light. However, scientists continue to research and explore the possibilities of faster-than-light travel.

How does travelling at the speed of light affect an object's mass?

As an object approaches the speed of light, its mass increases exponentially. This is due to the effects of time dilation and the object's increased energy. At the speed of light, an object's mass would theoretically become infinite.

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