The approximate explanation says that it is a Doppler shift. When an ambulance is moving toward you the pitch of its siren is higher than when the ambulance moves towards you. The motion of the ambulance "pushes" the wave crests of the sound closer togeter in the direction of motion and spreads them apart away from the direction of motion. This change alters the frequency of the sound and hence the pitch. A similar argument is propsed for why light from a galaxy that is moving away from us appears red.
Now here is a thought experiment to explain why this is a misconception when dealing with light. Imagine that you are travelling on a beam of light. When you get emitted from your host galaxy the universe is young, perhaps our galaxy has not even assembled itself yet. The expansion rate of the universe is low and so your "Doppler shift" will be quite low. By the time you reach my eye much time has passed. The expansion rate of the universe has increased and the redshift I measure is concurrent with that fact, not with the recession velocity of your host galaxy at the time that you were emitted. When then did your photon learn of the increase of the expansion of the universe?. The Doppler principle can not explain this. The correct answer comes from the metric of space and time itself. The semi-classical photon is intimately tied to space itself. (from here on in the explanation becomes touchy feely and I can only recommend looking at the maths and a proper derivation of the cosmological redshift.) I believe that the true answer will not come out until we have a quantum theory of gravity and it will be discovered that the boundary conditions of the photon are connected to the geometry of spacetime. This is certanly the effect we see at the moment with the redshift but that statement might be meaningless. If you imagine that it is true than you can almost imagine that the photon gets streched as spacetime expands because the photon is connected with the idea of measurement and length and the structure of spacetime. I can't really say much more than that.
In 1929, the American astronomer Edwin Powell Hubble linked the redshift visible in the spectra of distant galaxies, to the constant expansion of the universe.
Hubble suggested that this cosmological red shift is caused by the Doppler Effect, as the space through which the light travels, is stretched out. This would hence indicate the speed of recession of these galaxies -- and, by using Hubble's Law, the distances of the galaxies.
A second mechanism for red shift is the gravitational red shift, also called the Einstein shift. It was predicted by Albert Einstein with his general relativity theory -- According to which periodic processes are slowed down in a gravitational field. This Einstein Shift is noticeable in the spectra of massive, compact stars, such as white dwarfs.
Originally, there was to be a follow-up full LP, Blueshift, however internal problems at Java/Capitol caused the album to be permanently shelved, and for Splashdown to ultimately leave the label entirely.
This also ended up being the last official release of Splashdown anywhere. The group all went their separate ways (while reportedly staying "good friends") about two years after its release.
Track Listing
printable version chaos
Everything2 Help
