How Light Travels Across Space at Velocity C

In summary, the conversation discusses the concept of time and space for objects moving at the speed of light, specifically a photon. It is argued that for a photon, time does not exist and space becomes a single point. The idea of length and time contraction also breaks down for photons. The photon's frame of reference is non-inertial and the spacetime interval between events on its worldline is 0, making it neither timelike nor spacelike.
  • #1
DB Katzin
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In another post there is an example of a vessel moving close enough to the speed of light that the journey to the galaxy Andromeda 2.5M light years takes only 4 hrs on the vessel's clock. In its own frame of reference the vessel is moving just above 600K LY/hr. Yet a photon that left at the same instant would arrive before the vessel and always be measured as traveling at velocity c with respect to the vessel. As the velocity of the vessel S/T approaches the speed of light T (actually delta t) approaches 0, ie the 2.5 M LY trip takes, 3 hrs, 1 hr, 1 minute, 1 second, etc as v approaches c. At c, T (delta t) = 0, for all distances S, implying that time does not exist for a photon. In the photon's frame of reference its arrival and departure and the trip in between are simultaneous, its velocity is effectively infinite and since no time passes it doesn't age no matter how "old" it is--how long ago it was emitted.
 
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  • #2
Yes, time does not exist for an electron, it does not "age".
 
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  • #3
"In the photon's frame of reference"
This does not exist.
 
  • #4
Space also becomes a point.
 
  • #5
Coto said:
Space also becomes a point.

Why doesn't space become a two dimensional surface, given that length is only contracted along the direction of movement?
 
  • #6
I was just ragging.

IMHO, the ideas of length and time contraction breakdown for photons. But that's just an opinion with no justifying science behind it.

Edit: Sweet, that was my 100th post.
 
  • #7
The photon's frame of reference is non-inertial and poorly defined, but the spacetime interval between any two events on the photon's worldline is indeed 0. You cannot really say that this interval represents either proper time or proper distance since it is neither timelike nor spacelike.
 

1. How does light travel through space?

Light travels through space as a combination of both waves and particles. This is known as the wave-particle duality of light. It travels in a straight line and has a constant velocity of approximately 299,792,458 meters per second, also known as the speed of light.

2. What is the speed of light?

The speed of light is approximately 299,792,458 meters per second, which is equivalent to about 670,616,629 miles per hour. This is the fastest speed at which anything can move in the universe.

3. How does light travel through a vacuum?

Light travels through a vacuum by propagating as an electromagnetic wave. In a vacuum, there are no particles or atoms to slow down the light's movement, so it can travel at its maximum speed.

4. Can light travel forever in space?

Yes, light can travel forever in space. As long as there is no obstruction or absorption, light can continue to travel through space at its constant velocity. This is why we can see light from stars and galaxies that are billions of light-years away.

5. Does light always travel at the same speed in space?

Yes, light always travels at the same speed in space, regardless of the direction or the observer's frame of reference. This is a fundamental principle of Einstein's theory of relativity.

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