# Speed of light? Or velocity of free space?

1. Nov 20, 2005

### dgoodpasture2005

Light travels at approximately 186,000 m/s. as long as it is in its "natural" environment(space)... but put it in a vacuum and things change. So tell me then... Why do we call it the speed of light still? How about the velocity of space. So now... let's discuss this... please do not lock this thread, it is completely feasible.. and is not coming from a speculative pedestrian.. so i think it fits inside the S&D forum guidelines.

Last edited: Nov 20, 2005
2. Nov 20, 2005

### GOD__AM

How so? Space is a vacuum, or at least the closest thing we have to a vacuum. Even when light is interacting with matter it still travles at the same velocity. We only say the speed is different because the atoms absorb then re-emmit the photons causing a delay in the propigation.

Unless you can prove that the vacuum of space is made of some kind of "substance" I dont see how we can give it a velocity. What it the velocity of nothing?

3. Nov 20, 2005

### dgoodpasture2005

Yes, this is my point... when placed in an artificial vacuum light acts/interacts and travels at different speeds... let light flow in space and it flows back at 186,000 m/s. Space must be made of some substance.(energy/atoms/molecules, make up) Can you prove it's not? "...the velocity of nothing?" this is what i'm trying to get at. Right now it's nothing.. unfortunately i cannot blast off into space and do experiments.. I'd much like that :) The way light acts and loses its characteristics when placed in a vacuum(or taken out of space) would lead one to believe that, yes... space has a unique make up that gives light its unique properties in that environment. It's not light that is allowing light to travel at 186,000 m/s, it's space.

Last edited: Nov 20, 2005
4. Nov 20, 2005

### dgoodpasture2005

Theories are never complete, laws are made to be broken, the only thing that never changes is a constant, and the only thing constant is change.

5. Nov 20, 2005

### Ivan Seeking

Staff Emeritus
The speed of light in vacuum is ~186,000 mps. If a photon encounters something in space such as a hydrogen atom, it is absorbed, or absorbed and re-emitted. In the case that it is re-emitted, a propogation delay results but the speed in between atoms is still the 186,000... So in reality the speed of light is always the same.

Again, if you have science questions then please post to a regular physics forum. If you wish to post a theory, then please review the independent research posting guidelines.