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is there really a speed of light?
yes 76%  76%  [ 13 ]
nobody knows for sure 0%  0%  [ 0 ]
why the hell does this bother you? 24%  24%  [ 4 ]
Total votes : 17
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PostPosted: Thu Aug 05, 2004 10:10 pm 
Given:
The speed of light in vacuum is 186,000 miles per second.
The earth is moving very fast, it spins, tilts, and wobles, orbits the sun, our solar system moves withen our arm of the galaxy, it is also moving up and down in the galaxy, our arm of the galaxy is orbiting the center of the galaxy, our galaxy is probably moving relitive to the other galaxies in the local group and the local group is moving away from other galaxies, and more I'm sure

So given all that why isn't the speed of light faster in one direction than another?
This question has been bothering me for years and I don't know who to ask for an answer.


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PostPosted: Thu Aug 05, 2004 11:16 pm 
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http://en.wikipedia.org/wiki/Special_relativity

Basically:

1. there is no single universal reference frame from which all things are measured.
2. all the inertial reference frames have the same laws of physics.
3. the speed of light... is a law of physics.

Reconciling the third with the first two (known as Galilean or Newtonian relativity) requires the Lorentz transformations, which entails using length contraction and time dilation - basically as something moves faster relative to you, it becomes shorter in the direction of motion and its clocks move slower... but at the same time you become shorter in the direction of motion and your clock slows down, as seen from an observer on the fast moving thing.

Vorn


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PostPosted: Sun Aug 08, 2004 10:16 pm 
Kitty_Stew wrote:
---snip---The earth is moving very fast, it spins, tilts, and wobles, orbits the sun, our solar system moves withen our arm of the galaxy, it is also moving up and down in the galaxy, our arm of the galaxy is orbiting the center of the galaxy, our galaxy is probably moving relitive to the other galaxies in the local group and the local group is moving away from other galaxies, and more I'm sure---snip---


Thanks a bunch, now I'm permanantly dizzy.

The short (math-free) answer is that the frequency of the emitted light changes if the source is moving relative to you. This is called the Doppler Effect, and it is easy to observe with using a source of sound that is moving relative to you.

So with a moving omnidirectional light source the light going forward actually has a shorter wavelength than the light coming out of the rear of the source.


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PostPosted: Mon Aug 09, 2004 12:52 am 
True. It works with sound as well. Car, plane etc noises rise in pitch when they approach, and drop in pitch when they fly away from you.


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PostPosted: Mon Aug 09, 2004 3:37 am 
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BBlalock wrote:
Kitty_Stew wrote:
---snip---The earth is moving very fast, it spins, tilts, and wobles, orbits the sun, our solar system moves withen our arm of the galaxy, it is also moving up and down in the galaxy, our arm of the galaxy is orbiting the center of the galaxy, our galaxy is probably moving relitive to the other galaxies in the local group and the local group is moving away from other galaxies, and more I'm sure---snip---


Thanks a bunch, now I'm permanantly dizzy.

The short (math-free) answer is that the frequency of the emitted light changes if the source is moving relative to you. This is called the Doppler Effect, and it is easy to observe with using a source of sound that is moving relative to you.

So with a moving omnidirectional light source the light going forward actually has a shorter wavelength than the light coming out of the rear of the source.



So if you were in a car going 99% the speed of light, and you flicked your headlights on, then you'd probably end up subjecting the poor schmoe in front of you to a terrible burst of gamma rays.

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PostPosted: Mon Aug 09, 2004 3:54 am 
Ogredude wrote:
So if you were in a car going 99% the speed of light, and you flicked your headlights on, then you'd probably end up subjecting the poor schmoe in front of you to a terrible burst of gamma rays.

That sounds about right. I hate tailgaters.


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PostPosted: Mon Aug 09, 2004 1:26 pm 
That explains why people behind me are always blinding me on the freeway at night.

Or maybe that's just because the assholes are using their high-beams.


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PostPosted: Mon Aug 09, 2004 3:13 pm 
So is somebody going to answer this guy's question or not?


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PostPosted: Mon Aug 09, 2004 3:21 pm 
The General wrote:
So is somebody going to answer this guy's question or not?


Vorn did in the first response.


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PostPosted: Mon Aug 09, 2004 7:19 pm 
gwalla wrote:
The General wrote:
So is somebody going to answer this guy's question or not?


Vorn did in the first response.


Yeah, but then people started talking about the Doppler effect for some reason.


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PostPosted: Sun Aug 15, 2004 7:34 pm 
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The General wrote:
gwalla wrote:
The General wrote:
So is somebody going to answer this guy's question or not?


Vorn did in the first response.


Yeah, but then people started talking about the Doppler effect for some reason.


Well, the question was answered, and so people start talking about... whatever.

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PostPosted: Tue Sep 21, 2004 2:06 pm 
Doppler effect:
yes, this does apply to light waves, it is responsable for the red shift we see in other galaxies.

Speed problem:
The speed of light in a vacume is a wavefront moving across space-time. attempting, (rather clumsily) to put this in simple terms even I can understand, light "appears" to be moving at that speed, relative to the viewer. as your own speed approaches Cee, Time around the subject is also distorted, so that from thier point of view, oncoming or outgoing light continue to appear to move at the same speed.

ok, I give up. Reading Stephan Hawkings books made my head spin, and trying to explain the concepts that laid the foundations for his theories also makes my head spin.

Read "The Universe in a nutshell". Once you finish that book, you should be able to accept this theory just fine. Although I still struggle with a few other concepts contained therein.


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PostPosted: Sat Jul 30, 2005 2:08 am 
right Special Relativity, thats what I have a problem with, this part

forgive me I forgot how to quote, but right from wikipida:

Special Relativity rejects the idea of any absolute ('unique' or 'special') frame of reference; [and] physics must look the same to all observers travelling at a constant velocity (inertial frame).

physics must look the same and there is no universal frame, I cant believe they can say that in the same sentance. It seems to me you can have one or the other but not both. How can the speed of light be a constant if there is only local frames?

Dam it I'll come back in a year or so and try to explain my problem with time dilation, and ask for help understanding the relationship between time, mass, gravity and speed, but for now Im too tired to think about this

I can never just sit down and type all this out at once it seems

how do we know physics must look the same and time needs to be warped to accomplish this effect? Are we scewing up 13billion cubic light years worth of universe by observing it? Or is the time dilation God's way of keeping us from observing things outside our local frame?
ANd why doesn't light move faster in one direction?


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PostPosted: Sat Jul 30, 2005 3:27 pm 
Anonymous wrote:
physics must look the same and there is no universal frame, I cant believe they can say that in the same sentance.


Why can't you believe it? It's what they're explaining.

Quote:
It seems to me you can have one or the other but not both. How can the speed of light be a constant if there is only local frames?


Because of time dilation. Time flows differently for each inertial frame.


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