What evidence do you have to support the big bang?

Answer 1

The evidence that the space that constitutes our Universe has been expanding since about 13.7 billion years ago is overwhelming.

1) all galaxies outside our Local Group are red-shifted, meaning the distance between these galaxies and us is increasing.The size of this red shift is directly proportional to the distance between us and those galaxies. The time when all of the visible (to us, anyway) matter was compacted as far as we can understand, is called the Big Bang. Calculation of the Hubble Constant gives that time at about 13 billion years ago. Interestingly, this time agrees with the ratio of slow-decaying elements AND the age of the oldest known stars.

2) this hypothesis predicted, in 1946, the existence of an isotropic and uniform microwave radiation whose spectrum would match that of a black-body at 3.7 K. The cosmic microwave background radiation was found eighteen years later and corresponds perfectly with the prediction.

3) the hypothesis predicts that all parts of our Universe would constitute 90% hydrogen and 10% helium -- exactly as seen.

No other hypotheses can explain (2) or (3) better than saying, "That's just the way our Universe is -- we can't explain why."

4) Long-evolved galaxies are seen close to us, but none are seen far from us. This is impossible to explain EXCEPT with the simple idea that, at a far distance from us, we can ONLY see galaxies that have not had time to evolve for a long time.

Edwin Hubble discovered that the distances to far away galaxies were generally proportional to their redshifts-an idea originally suggested by Lemaître in 1927. Hubble's observation was taken to indicate that all very distant galaxies and clusters have an apparent velocity directly away from our vantage point: the farther away, the higher the apparent velocity.

Answer 2

The #1 evidence seems to be the redshift of distant galaxies, usually attributed to the Doppler effect. Another piece of evidence is the cosmic background radiation, which is in close agreement to models about the Big Bang.

Answer 3

The most commonly cited evidence is the metric expansion of space. It is inferred from Hubble's law that the Universe is expanding faster and faster with time, due in roughly equal proportions to the Inertia of Galaxy Super clusters
Galaxies are NOT moving away from each within space due to a force or because momentum carries them -- it is SPACE ITSELF that is expanding, and matter is simply going along for the ride.

If we backtrack on this idea, we come to the conclusion that all of this matter must have originated at the same point at one instant in time, and started moving apart at another.




When the big bang first went "bang," all matter was in the form of elementary particles, such as electrons, protons and neutrons. This was all at a very high temperature, so when the young universe exploded outward, the pressure drop caused the temperatures to drop low enough that the protons and neutrons can 'recombine' with electrons to form neutral atoms.
When doing the calculations, Big Bang Cosmology predicts that, in this early time of our Universe, our Universe would end up about 20% helium and about 80% hydrogen. That's exactly what is observed in all parts of our Universe, which is impossible to explain UNLESS Big Bang Cosmology is true.

Answer 4

For more details, I suggest you check the Wikipedia article on Big Bang. But briefly:* The Second Law of Thermodynamics suggests that the Universe must have had a start.

* Calculations show that the Universe can't remain stable - sooner or later, it must either expand, or contract.

* Galaxies generally move away from one another, as evidenced by their redshift.

* The percentage of individual elements, as well as isotopes, matches the expectations of the Big Bang quite closely.

* The cosmic background radiation closely matches the expectations of the Big Bang.