amitmis said:
hello,
i'm amit from israel, and i'd love to be an activated member in your forum.
my first question - are there other theories about the beginning of the univers. except of "the big bang" (not religion)?
thanks,
amit
Hello amit from Israel, I'm Garth from England, welcome to these Forums!
You will get the opportunity to ask many questions here because that is how we learn!
There is strong evidence that the universe went through a period of intense compression and temperature from which it has expanded, the Big Bang.
The three main pieces of evidence are:
1. The Hubble Red shift, interpreted as a Doppler shift of the other galaxies and quasars, which are receding from us as the consequence of that expansion.
2. The Cosmic Microwave Background which is an all-surrounding bath of radiation at a temperature of 2.7
0K. This if you like is the 'echo' of the BB, received not as a sound but as a 'flash' of radiation now much red shifted into the microwave region of the electromagnetic spectrum.
3. When all the nucleosynthesis that has gone on inside stars has been taken into account it seems that the original mix before our galaxy and its stars existed was about 3/4 hydrogen and 1/4 helium (by mass). How can this be explained? When the BB is considered as a vast nuclear explosion and the nuclear reactions worked out it transpires that what should come out of the BB should be 3/4 hydrogen and 1/4 helium (by mass)! This agreement is very difficult to explain otherwise.
The accepted and tested theory of gravity, General Relativity, allows one to predict back from the present into the very first moments of the BB and GR on its own does not allow an alternative to an initial singularity (zero volume, infinite mass density and temperature). However at some stage GR must break down as the entire universe is then compressed into a region over which quantum effects would predominate. It is possible that such effects might (when predicting backwards in time) enable the BB singularity to be avoided. There might have been a 'bounce' from an earlier universe. The BB certainly is a beginning of our universe but of conjecture about other universes there is no end, unfortunately we can't see any of them!
So there are different theories about the beginning of the universe. Of course it also all depends on what units of mass, length and time you use, and how you make measurements at the other end of the universe. But such approaches are probably a bit advanced for now!
Garth
