Scientists:(preferably cosmologists)- i have questions?

Question

Hello people. i have a couple questions

1. what is the theory of general relativity? how does it proof that the universe is finite? (i tried to research it, but couldn't really understand it. i'm 16 and science isn't my strong point) . so please explain it as simply as you can.

2. also, the second law of thermodynamics states that the universe is running out of usable energy. i don't understand that concept. please explain it to me.

3. before the Big Bang, there was no space time or matter, there was nothing. and then the universe just popped out of nothing. where did first matter come form? matter couldn't have just existed without time and space, so where did the time and space come from? Time and space couldn't have always existed. if something has always existed then it's eternal. but space and time aren't eternal. eternity is when there is no space and no time.

and if before the big bang there was a vacuum, a quantum vacuum isn't absolutely nothing. it is fluctuating energy. so where did this energy come from?

Answer 1

Wow, one could write a book about these questions. Several books!

1) General Relativity is the theory of gravity as developed by Einstein. Applied to the Universe as a whole and using the observation that the Universe is expanding, the most likely solutions then indicate a Universe with a finite mass.

2) The second law of Thermodynamics says that temperature differences between systems in contact with each other tend to even out and that work can be obtained from these differences.  This means that a closed system like the Universe will eventually come to have the same temperature everywhere so that no longer any work is possible.

3) The scientific theory is that the Universe started as a fluctuation of the vacuum. Such vacuum fluctuations make appear a small amount of energy, for a small time. This phenomenon is responsible for the existence of forces, that hold the Universe and matter together.

Normally the bigger the energy fluctuation, the smaller the time it is in existence.

Not so the Big Bang. That was a HUGE fluctuation. So big that a lot of energy came to appearance in the form of mass, elementary particles. These particles started expanding, before the vacuum could reclaim the energy.