What is Red Shift and Dark Energy in regards to space expansion??

Answer 1

When objects (such as stars) move away from an observer at great speed - as happened according to the Big Bang theory - their light shifts frequencies, increasing wavelengths.

Visible light is part of the electromagnetic spectrum and, like a rainbow, violet is at one end, red at the other. Red has a longer frequency than the normal colour of a star, which might be yellow or orange.

Think of the wavelength being a piece of string attached to an object you throw away - the string gets taut and any kinks (waves) are straightened out. It's a variation of Doppler theory, which you'll encounter everyday an emergency vehicle passes you. the siren changes pitch as the vehicle passes - in this case the sound has changed wavelength.

Dark energy is a cosmological hypothesis which explains how the universe can continue to increase its rate of expansion. Basically, there is not enough matter present in the universe to allow for this to happen, but the presence of dark matter would allow for the observed effects.

The existence of Dark Matter has yet to be proved, but if it was, then it would probably be one of the most important discoveries in cosmology since background radiation from the Big Bang.

Answer 2

The RED SHIFT is the change of frequency for the electromagnetic waves coming to the Earth from far galaxies. As the galaxies are receding, the Doppler Effect increases the wavelength (and reduces the frequency). The farther is a galaxy, the lower would be the frequency (The red color have less frequency than the other colors).
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The dark energy (DE) is a hypothetical energy but nobody knows how it works... For me is like the Einstein repulsion constant.... =bs
Where is the DE? Did the DE move? If yes, what is its speed? Where is it going? Did the DE have weight? >=< 0? The gravity affect the DE? The Doppler Afect the DE?

Answer 3

Red shift is caused by the Doppler effect where things moving away from you tend to stretch out light and shift it a little to the red. This can be seen in spectrographic studies of absorption lines that are shifted to the red side. See---
http://en.wikipedia.org/wiki/Redshift
This shows that the universe is expanding.
Scientists think that it should be expanding faster. Dark matter may explain this and a bunch of other things that don't fit the model. On the other hand some think the universe is expanding to fast for the model or is sort of pulsing and they think dark energy is behind this effect.
See---http://en.wikipedia.org/wiki/Dark_energy
My guess is that we need better equipment to study all this. And a few more years of observation, like maybe 1000 years. The sample we have is just to small, good work takes time. Its all so confusing when the best scientists can't even agree.

Answer 4

Red shift is a shifting toward the red end of the spectral lines of visible light from bodies that that are moving away from us at great speed. Dark Energy is only a proposal by scientists to explain the continuing expansion of the universe.

Answer 5

There is a lot of misunderstanding about redshift - even from qualified astronomers!

The red-shift of starlight is a decrease in the energy of the light. This energy decrease results in a lengthening of the wavelength of the light, measured with an instrument called a spectrometer. Red is the rainbow color with the longest wavelength, hence the name "red-shift." Stars do not actually become red in appearance since the wavelength change is usually slight. Almost every star and galaxy is found to be red-shifted. The following list summarizes some of the alternative explanations for the origin of this stellar red-shift.

1. Stellar Motion. If a star moves outward from the earth, its light energy will be reduced and its wavelength stretched or red-shifted. Stars and entire galaxies show varying amounts of red-shift, therefore implying a variety of speeds for these objects. Police actually use this same effect with radar to measure the speed of cars. Stellar motion is often taken as evidence in support of the Big Bang theory. Stars are assumed to be speeding outward as a result of the explosion.
Einstein’s theory of general relativity says that in an expanding space, the lengths of light waves should be stretched out right along with the stretching-out of the medium they are moving through. Light coming from distant objects would have experienced more such stretching than light from nearby objects, so such redshifts would increase with distance.
Today, most cosmologists think that the observed redshift is an expansion redshift, not a Doppler shift.
This is not the only explanation of red-shift, however.
2. Gravitation. As light leaves a star, the star's gravity may slightly lengthen the wavelength of the light. A gravitational red-shift could also result from starlight passing near a massive object in space, such as a galaxy. As the light escapes from a strong gravity field, it loses energy, similar to what happens to a person struggling to the top of a mountain.
3. Second-Order Doppler Effect. A light source moving at right angles (tangentially) to an observer will always be red-shifted. This can be observed in the laboratory by using a high-speed turntable. A detector is placed in the center and a gamma radiation source is placed on the outside edge. The gamma energy is seen to decrease, or "red-shift," as the turntable speed increases. This is an intriguing explanation for stellar red-shift. When applied to stars, it implies that the universe may be in circular motion instead of radial expansion.
4. Photon Interaction. It is possible that light waves exchange energy during their movement across space and lose some energy in the process. A loss of light energy is equivalent to a "reddening" of its light. A theoretical understanding of this proposed "tired light" process has not yet been developed.

Any of these four explanations, alone or in combination, may be responsible for red-shift. We do not know enough about space to be certain of the source of stellar red-shift.

http://www.creationontheweb.com/content/view/3842#66

technical:
http://www.creationontheweb.com/content/view/1570

Answer 6

Red shift refers to a change of wavelenght on the red end of the visible radiation spectrum .A blue shift would refer to a change of radiation at the high end of the radiation frequency of the visible spectrum.

It is caused by the following possible scenarios ;
Blue shift due to high gravity field density in space.
Doppler effect of the motion of light.
Dispersion effect of the medium of space

Dark energy is the result of the Power stored in the substance of space identifed as dark matter.
Space does not really expand . it is the Galaxies that ether expand or contract their radius vector inside the finite volume of the Universe.
So dark matter is responsible for both expansion or contraction depending on the Density of the Vaccum energy density of the substance of space.

It very vely simple

Answer 7

Red shift indicates stuff is getting farther away because it's expanding. If it was collapsing, there would be a blue doppler shift. If it was steady size, there would be no doppler shift. Dark energy is a theory explaining why space isn't expanding as fast as it seems like it should be.