we can tell what a substance is made from by the spectrum of light it produces, so why, if the speed of light is constant, does the light move into the red, or green spectrum if the galaxy is moving away, or toward us?
2006-07-24 07:36:13 · 9 answers · asked by caprilover79 3 in Science & Mathematics ➔ Astronomy & Space
To expand on the previous answers,
When something is moving away from you, the light from it gets 'red shifted'. That means the frequency is shifted towards the red direction.
When something is moving towards you, the light from it gets 'blue shifted'. This means the frequency is shifted towards the blue direction.
Frequency shift does not necessarily mean there is a speed shift.
The relation is that if the speed is constant, then as Energy increases so does the frequency. The frequency is inversly related to wavelength.
Look at the Astronomy section in the source link
2006-07-24 07:57:13 · answer #1 · answered by Vicente 6 · 1⤊ 0⤋
C is light speed in a vaccuum. Light like sound moves at different speeds in different substances. Different parts of light are slowed down to greater or lesser degress due to their wavelength, thats why light "bends" when it hits the surface of a substance at an angle. Red shift (which im not so sure of) works in the same way as the sound of a car coming towards you changes when it moves away. The wave "catchs up" with itself coming towards you and "spreads apart" moving away. Changing the wavelength. Thats what I think anyway. Youll have to try a science textbook or online resource for a proper answer I think.
2006-07-24 08:30:19 · answer #2 · answered by pinkyandbunty 2 · 0⤊ 0⤋
Many of the answers above relating to the red shift and blue shift are correct.
In simple terms, a supersonic plane is emitting sound waves. When it reaches a critical speed the emitted sound waves in front are progressively 'compressed' until the plane is above the speed of sound and the plane can not be heard approaching.
The speed of light is constant but it either 'shifts' towards the red or blue spectrum depending upon whether the light is approaching or receding. i.e. Light waves being compressed or extended.
Sometimes referred to as the 'Doppler Effect'.
2006-07-24 09:39:14 · answer #3 · answered by CurlyQ 4 · 0⤊ 0⤋
Firstly its red shifted or blue shifted, no green. Think of the doppler effect whereby a train travelling towards you will have a sound which gets higher in pitch the closer it gets and then gets lower in pitch as it moves away again. This is purely the listeners perception of the sound increasing in frequency and then decreasing in frequency.
The same applies to light, the light you are seeing itself is constant but where you are viewing the light from alters your own perception of that light.
2006-07-24 07:43:45 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Speed of light depends on the speed of its constituents. For all practical purposes, the speed of light is constant and does not change. The shifting effect is as already stated due to the wavelenghts.
But, the question here is, can you speed up light? If you speed it up, will it still be light? If you think of light as photons, it can be speeded up theoretically. The dual nature of light makes it difficult to speed up light.
2006-07-25 02:42:19 · answer #5 · answered by si11y13yte 2 · 0⤊ 0⤋
Because when a galaxy moves away or towards us the light emitted changes its wavelength not its speed.
2006-07-24 08:34:39 · answer #6 · answered by Dirk Wellington-Catt 3 · 0⤊ 0⤋
Once the speed of light is slow enough, light behaves like a liquid. Scientists have actually stopped and reversed light.
2006-07-24 09:22:41 · answer #7 · answered by Anonymous · 0⤊ 0⤋
galaxy is moving way from us and light is shifting to the red.
2006-07-24 08:04:31 · answer #8 · answered by rinjam 2 · 0⤊ 0⤋
Ummmm, because light is female and hence fickle.......?
2006-07-24 08:19:41 · answer #9 · answered by Anonymous · 0⤊ 0⤋