How does a redshift give evidence to the Big Bang Theory?

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Trippy Share
Nov 24, 2015

Answer:

More information in the explanation.

Explanation:

In the beginning(or well, before the beginning), the Universe was nothing but a blob, an infinitely small point. And suddenly, that point started expanding exponentially and has been expanding and accelerating ever since, expanding into what it is now and what will be in the future.

Well, how can a redshift of light, or Doppler Effect, give evidence to the Big Bang Theory?

To understand what the Doppler Effect is, let's use this analogy which is generally used to understand the concept:

Imagine you have an ambulance with a siren on coming towards you, as the ambulance approaches you, the siren sounds high-pitched, as the sound waves are very compressed, but as the ambulance goes past you, the siren becomes ever more low-pitched, as the sound waves become more stretched.

That's essentially the Doppler Effect, in this case with light, if the object is coming towards you, it appears to be blueshifted, as the wavelenght is very compressed and at the blue end of the spectrum, however, if the object is moving away from you, the light becomes redshifted, as the wavelenght is stretched and on the red end of the spectrum. To achieve these effects though, the object must be moving at high speeds.

Now that we have the notion of Doppler Effect, let's tackle the question.

If we were to observe the Universe, and were expecting the Universe to be somewhat static, we'd see the roughly the same number of red-shifted galaxies as blue-shifted ones. However, through observations, which were done for the first time by Hubble, we know that most galaxies are actually red-shifted, meaning that they're all moving away from us, and eachother, as the galaxies farther away from us are actually the ones moving faster away from us.

This means that the Universe is indeed expanding, and at a fast rate, from what we observe from Red-shifting. And well, the model of The Big Bang suggests that from a small singularity, an expansion started, and has been ever since. Therefore, red-shifting gives evidence to support The Big Bang Theory.

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Dec 7, 2016

Answer:

The red shift indicates that the universe is expanding outward at an ever increasing rate of expansion.

Explanation:

When Hubble determined that the vast majority of stars and galaxies had a red shift, he created a major shift in the world view or paradigm that dominated science. The universe before Hubble was thought to have eternally existed, a so called steady state universe.
After Hubble the presently observed universe could no longer be consider to be eternal.

A red shift in light indicates that the object is moving away from the observer. This is called the doppler shift. or effect. Stand by a railroad track and listen to the train whistle. As the train is moving toward you the sound is higher ( the waves are closer together) when the train passes the sound changes to a lower pitch ( the waves are further apart) blue light has waves that are closer together and red light has waves that are further apart.

The logic is that if the universe is observed to be moving apart it must have been closer together in the past. The big bang theory is that the universe is moving apart from a central point that once existed. In classical Big Bang theory this central point is proposed to have been a superdense ball of matter. The superdense ball was so dense that it was unstable and exploded. This explosion caused the universe that we presently observe.

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