[yor_on]

Yeah, that was what I thought, but seeing the answer I got unsure..
It felt like if I had missed something really basic for a while there

[Geezer]

Is it true that, while the speed is constant for all observers, the frequency is not?

[JP]

Is it true that, while the speed is constant for all observers, the frequency is not?

I do believe that if you apply the equations for the waves, you should easily find this is true.

[yor_on]

"Sherlock!"

"Yes Wattson"

"They are stealing our mojo"

[JP]

More seriously, wavelength and frequency can change with observer, since measurements of time and space won't necessarily agree.  The speed of light is the same for everyone in a vacuum (that's one of the postulates of special relativity).

In a medium, all three can vary from observer to observer.

[Geezer]

Arn't there really only two variables? Doesn't frequency always have to be consistent with wavelength?

[JP]

Yes, it will satisfy a dispersion relation, which is the relationship of frequency and wavelength to speed of the light, so if you know the dispersion relation and two of the three parameters, you can get the third.

[Bill S (OP)]

The propagation of light in a vacuum is allowed by properties of the vacuum itself, which are different from those of matter.  This is why the speed of light in a vacuum ends up being constant for all observers, while in a medium it isn't.

Thanks JP.  Obviously, the trick is finding the kernels among all the nuts.  [^]

[Ron Hughes]

JP said, "The propagation of light in a vacuum is allowed by properties of the vacuum itself, which are different from those of matter.". Properties (vacuum) which are man made definitions. There is no way to directly look at those properties except by how radiation performs in it. In of words they don't have a clue as to what is space.

[Geezer]

JP said, "The propagation of light in a vacuum is allowed by properties of the vacuum itself, which are different from those of matter.". Properties (vacuum) which are man made definitions. There is no way to directly look at those properties except by how radiation performs in it. In of words they don't have a clue as to what is space.

Ron, I don't think the definitions are intended to define what it "is" exactly. They are more a pretty accurate description of what it "does" based our observation of radiation, and possibly, other things. I think it's fair to say it is not a form of matter as matter is usually defined.

How space manages to do what it apparently does is quite fascinating to me. I hope I live long enough to get a better sense of how it works, although I'm not too optimistic about that.

[Ron Hughes]

If we define space as the electric field of every charged particle in the Universe would that be a fair description of it?

[yor_on]

Not if you can't prove electricity getting 'stored' in it. To build an expression of a 'electromagnetic' space you will need to prove it existing. And as light only exist in a interaction?

[Ron Hughes]

yor-on, does the electron and proton have an electric field that has been expanding since their creation? Yes. Therefore I submit that space is that electric field.

You said, "And as light only exist in a interaction?", yes just as JJ Thompson showed that interaction as a change from where that field was to where it is now. http://www.thenakedscientists.com/forum/index.php?topic=34333.0;topicseen