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-   -   Does light speed apply to all waves traveling in vacuum? (http://www.physicsforums.com/showthread.php?t=230871)

 Crazy Tosser Apr23-08 02:13 PM

Does light speed apply to all waves traveling in vacuum?

Seriosly, waves have different frequencies, and light is somewhere in the middle of the EM spectrum, then maybe the right or left side could travel faster than c

 lzkelley Apr23-08 02:36 PM

Light is generally the term used to refer to electromagnetc waves in the visual spectrum (but its really the same as other E&M waves, just at different energies).
They all behave generally the same, i.e. all E&M waves travel at the speed of light.

 Phlogistonian Apr23-08 05:23 PM

All massless waves (and all massless particles) travel at the speed of light.

 Danger Apr23-08 06:03 PM

That includes gravity, by the way.
I think that in one regard, you can say that not all waves travel at c in vacuum, but I'm not sure if my reasoning applies. It seems to me that the matter waves associated with a particle can't do so, since the particle itself can't.

 _Mayday_ Apr24-08 10:33 AM

CT, all EM waves travel at the same speed in a vacuum. As far as I am aware this is not the case when dealing with a medium in which the waves are travelling slower.

Quote:
 Quote by Phlogistonian (Post 1702759) All massless waves (and all massless particles) travel at the speed of light.
If by speed of light you mean around $3\times10^8$ then I can't see how that is correct.

 Lojzek Apr24-08 11:08 AM

Quote:
 Quote by Crazy Tosser (Post 1702467) Seriosly, waves have different frequencies, and light is somewhere in the middle of the EM spectrum, then maybe the right or left side could travel faster than c
The phase velocity of a wave is a product of the frequency and wavelength:

L*f=v

The electromagnetic wave equation has solutions with different frequences, but the wavelength must be inversely proportional to the frequency, so the product is always the same:

L*f=c

 bassplayer142 Apr24-08 11:11 AM

Quote:
 Quote by Danger (Post 1702805) That includes gravity, by the way. I think that in one regard, you can say that not all waves travel at c in vacuum, but I'm not sure if my reasoning applies. It seems to me that the matter waves associated with a particle can't do so, since the particle itself can't.

Has it been experimentally proven that gravity waves travel at the speed of light.

 Phlogistonian Apr24-08 11:35 AM

Quote:
 Quote by _Mayday_ (Post 1703482) If by speed of light you mean around $3\times10^8$ then I can't see how that is correct.
The original question was about waves in a vacuum.

 _Mayday_ Apr24-08 11:43 AM

Quote:
 Quote by Phlogistonian (Post 1703538) The original question was about waves in a vacuum.
That doesn't make what you said correct.

 Phlogistonian Apr24-08 11:58 AM

Quote:
 Quote by _Mayday_ (Post 1703552) That doesn't make what you said correct.
You can think what you want. I won't engage in a pointless argument over semantics.

 Crazy Tosser Apr24-08 01:59 PM

Well, how about traveling slower than the speed of light? If you are in a car that's goin at 100mph and you light a flashlight backwards, does the light travel at c-(100mph)?

 ZapperZ Apr24-08 02:03 PM

Quote:
 Quote by Crazy Tosser (Post 1703735) Well, how about traveling slower than the speed of light? If you are in a car that's goin at 100mph and you light a flashlight backwards, does the light travel at c-(100mph)?
Please refer to the basics on relativistic velocity addition.

http://hyperphysics.phy-astr.gsu.edu...iv/einvel.html

The speed of light is constant in all inertial frames, no matter the speed of the source.

Zz.

 rbj Apr24-08 02:37 PM

Quote:
 Quote by bassplayer142 (Post 1703513) Has it been experimentally proven that gravity waves travel at the speed of light.
only to within 20%, IIRC.

 Severian596 Apr24-08 03:43 PM

Quote:
 Quote by Crazy Tosser (Post 1703735) Well, how about traveling slower than the speed of light? If you are in a car that's goin at 100mph and you light a flashlight backwards, does the light travel at c-(100mph)?
Excellent question, CT, and the answer is very important (ZapperZ already mentioned it). Make sure to keep reading every text you can get your hands on, because we've all asked this question at one time or another; if you can accept the true answer it will blow your mind.

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