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FrozenGate by Avery

Doppler effect with light






Lets test this theory... *picks up IR laser and shines it past friend*

Me - "Is it still IR?"

Him - "Yes..."

Case closed...
 
VW said:
Lets test this theory... *picks up IR laser and shines it past friend*

Me - "Is it still IR?"

Him - "Yes..."

Case closed...
Click to expand...
You got it all wrong. The laser itself has to travel very, and I mean VERY fast while lasing towards the obsever to make it work. I think.
 
Yeah thats right FireMyLaser, the laser its self would need to be traveling at great speeds towards the observer in order for the effect to take place, same idea as the siren on a police car, only because sound travels slower the vehicle doesnt have to travel all that fast for the effect to take place.

Diachi
 
It's not like you just look at the laser and it changes colour.  The effect is called red shifting, astronomers used this technique to discover that the universe was expanding.  When they use a prism, the light from a particular star/galaxy etc gives off an imprint of elements on the light spectrum, sort of like a bar code.  Strangely, those elementary marks shift towards the red end of the spectrum if the object is accelerating away from us.  If it's moving towards us, those elemtary marks will shift to the opposite end of the spectrum.  Indeed, it is similar to the doppler effect, but it is vastly different in reality.  
 
how is it 'similar 'to the doppler effect but vastly different. It is exactly the doppler effect, it is no different.



If you are interested in the speed and wavelength shift you can use this

New wavelength = emitted wavelength * speed of light / (speed of light -/+ speed of emitter)
 
This works and happens every day all around us, though the shifts in wavelength over the distances and speeds of everyday objects is probably only enough to shift the color a few millionths of a nm, so it's not like a car that accelerates towards you is going to suddenly turn blue... it's only really noticeable on the scale of gigantic stars trillions of miles away traveling at millions of miles per hour.
 
likewhat said:
how is it 'similar 'to the doppler effect but vastly different. It is exactly the doppler effect, it is no different.



If you are interested in the speed and wavelength shift you can use this

New wavelength = emitted wavelength * speed of light / (speed of light -/+ speed of emitter)
Click to expand...
Are you trying to say sound and light are the same thing?  Try traveling at the same speed as the object and then tell me if they are the same.

http://www.youtube.com/watch?v=JQnHTKZBTI4

The effects light has at great speeds are way greater than that of sound. You have so much more to concider, like light is a constant for example and even relativity it's self...
 
VW said:
[quote author=likewhat link=1214677024/36#37 date=1215582232]how is it 'similar 'to the doppler effect but vastly different. It is exactly the doppler effect, it is no different.



If you are interested in the speed and wavelength shift you can use this

New wavelength = emitted wavelength * speed of light / (speed of light -/+ speed of emitter)
Click to expand...
Are you trying to say sound and light are the same thing? Try traveling at the same speed as the object and then tell me if they are the same.

http://www.youtube.com/watch?v=JQnHTKZBTI4

The effects light has at great speeds are way greater than that of sound. You have so much more to concider, like light is a constant for example and even relativity it's self...[/quote]


Yes, they are the same as far as the doppler effect is concerned. The speed of an emitter relative to the speed of a receiver, that is the doppler effect in a nutshell. When the relative speed becomes and appreciable fraction of the speed of light there is a correction for it to be relativistically correct. But for common uses of the doppler effect and lasers (laser cooling is the most common one) relativity doesnt enter.

The equation I put above works for sound too, just change the speed of light to the speed of sound.
 
Indeed, you are right. I guess the point I was getting at was that people didn't know light was an electromangetic wave untill the time of James Clerk Maxwell, quite a while after the time of Christian Doppler. It's because of this the doppler effect is commonly reffered to sound more so than light. Indeed the doppler effect is universal across waves, but light and sound do have their individual properties/uses in every day, and not so every day life.

For example if a laser flew past you at the speed of light, you wouldn't really see anything at all. It would be a lot harder to disdinguish the doppler effect through light than it would be through sound. In every day life, the front of a car doesn't turn blue and the back of a car doesn't turn red. Because of their individual speeds and the ways at which you can test the two , they are a lot different from each other in practice.
 
Everything happens and is observed relative to only the other observables. Everything else you don't observe, causes your observation. ;)
 
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