A good friend and colleague of mine sent me the following question:
"I have always been fascinated with "Space' and questions such as "Where does the Universe begin and where does it end?" Any comment?
Here is what I sent back to him and I thought I would share it with you:
Yeah, space is something else and it challenges us. Beyond the "big questions" it is so beautiful and peaceful to enjoy.
The questions you ask are indeed "big" and I will try to give you a simple answer. Our current best theory is that the Universe is 13.7 billion years old - having been created in an event we call the "Big Bang" - the moment in which all space and time erupted from literally out of nothing. Was there anything before the Big Bang? Some say this is a non-sensical question as the Big Bang created everything from a single event....others pursue the question on a purely mathematical basis.
The end of the Universe is a vexing question as we are still discovering new things all the time. Right now we know that the Universe is made of the stars and galaxies and people that we can see but that this is only a fraction of the mass (5%)that makes up the Universe. There exists far more Dark Matter (23%) than ordinary matter and we do not know for sure what Dark Matter is. There also exists Dark Energy (72%) - an unknown force that is accelerating the expansion of the Universe caused by the Big Bang.
Current theory states that the Universe is "flat" which means that it will expand "forever" and there will come a time when we will see no other galaxies due to the accelerating expansion. Stars have a finite life, and there is only so much raw material (gas and dust) to create new stars and planets, so at some point in the very distant future, all of the stars will have ended their lives and the Universe will grow dark. There is also a possibility that matter as we know it - atoms, electrons, quarks - has a finite life as well so the Universe ends up being nothing but a dark, vast graveyard of exotic ghost particles. Depresssing, indeed.
So, while there is light and life in the Universe we must make the most of it. Our own Sun will cease to exist in about 5 billion years as it will have used all of its hydrogen fuel and will become a Red Giant star, most probably enveloping our own Earth. Indeed, ashes to ashes, dust to dust will be the Earth's ultimate fate.
What do YOU think about this? I would like to know your opinion.....
Sky Guy in VA