Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Fluid_thinker on 14/03/2009 13:42:49

Title: Speed of light
Post by: Fluid_thinker on 14/03/2009 13:42:49

We quote the speed of light in a Vacuum.

But space is not a vacuum it is full of dust, gas etc etc.....

Or is it that our definition of a vacuum takes into account a non perfect vacuum.

How does this effect light travelling to us from distant galaxies?

Title: Speed of light
Post by: Vern on 14/03/2009 14:18:07

The mods are asking us to pose topic titles as questions. This is so that the search engines will pick up on them and give them more exposure.

Quote

How does this effect light travelling to us from distant galaxies?

Space debris consists of electrons, ions, atoms, chunks of mass of all sizes, and an unknown amplitude and mix of frequencies of electromagnetic radiation. Your question is very interesting. Maybe we should take the construct of space into account when we measure incoming light from distant sources.

Title: Speed of light
Post by: swansont on 14/03/2009 18:14:45

Quote from: Fluid_thinker on 14/03/2009 13:42:49

We quote the speed of light in a Vacuum.

But space is not a vacuum it is full of dust, gas etc etc.....

Or is it that our definition of a vacuum takes into account a non perfect vacuum.

How does this effect light travelling to us from distant galaxies?

Even with all of the dust, etc., space is still a pretty good vacuum.  The index of refraction of a complete physical vacuum is 1.  By comparison, the index of refraction of air at STP is 1.00029.   Space  has 18-19 orders of magnitude lower concentration of atoms.