Who hasn't looked up into the heavens and wondered where it all came from?
That, undoubtedly, is The Mother of All Mysteries. And it probably is an impenetrable mystery.
You see, I think that in the present universe there is no information regarding its true origin. If it's true that "a black hole has no hair", then the only information coming out of whatever banged in the Big Bang is its mass, spin and charge, and any information regarding whatever happened before that is irretrievably lost.
Why and how is the universe here? Not only is it incomprehensibly huge but it is also almost impossibly complex. The laws that govern its behavior are beautiful and mathematically precise. At they same time they are strange. If quantum mechanics rules the universe, then it is a universe beyond human intuition. Why are those laws what they are? How did they come into existence? Is there only one possible set of rules?
Human logic does not limit the workings of the universe. At the extremes our logic seems to fail. At very high velocities relativity overpowers Newtonian physics and things happen which we simply must accept. At the quantum level there is strangeness at every turn. Perhaps human logic is fundamentally flawed but we have no way of knowing how.
About 15 (10 TO 20) billion years ago an object exploded giving birth to the universe we know. That object seems to have had zero-volume and the entire mass-energy of our universe was concentrated in it.
A mathematical point of infinite density suddenly decided to explode? And where the heck did that fat little point come from?
That the Big Bang happened is nearly certain. The expansion of the universe and the microwave background radiation pretty much confirm it. The Big Bang Theory has its flaws, but it's the best we have so far.
Was all the information for forming the universe, laws, evolution, etc., somehow contained in that fat little point?
We don't know if the Universe is finite or infinite. We sort of desperately try to make it finite (closed), maybe because the concept of an infinite (open) universe is yet another one beyond our comprehension. We're not sure if there's enough matter to close the universe and make it collapse upon itself, reversing the current expansion.
And guess what? We can't even find 90% of the mass of the universe. Galactic clusters are bound together by the gravitational attraction of the matter contained within them, but only 10% of the necessary amount of matter is in the stars themselves. The rest is in the form of "dark matter", the nature of which is unknown.
To me, a pulsating universe seems to be more symmetric. We would not have to worry about explaining what came before the Big Bang because it would simply be another one of an infinite number of oscillations. And in the future, it would continue to cycle in the same manner forever. Large-scale events would be pretty much repetitive, unless the laws of physics change with each cycle.
Of course, a cyclic universe would not answer the fundamental questions of how or why it exists.
Unfortunately for the pulsating idea, evidence has recently been found which seems to support the notion that the universe will expand forever. In fact, the expansion of the universe is accelerating rather than slowing down.
That, my friends, is not supposed to be happening!
It may be that Einstein's infamous cosmological constant, which he called his greatest blunder, may have a role in physics after all. Either that or there is a "dark energy" which cosmologists call quintessence, a sort of "ether" which pervades the universe and provides a way for repulsive gravitational forces to exist.
I really hate this because it means that there probably was an absolute beginning. No pulsating universe, no symmetry.
And I really love this because it gives us hope. The impenetrable mystery of the true origin of the universe is one which nobody can dismiss... atheist and believers alike.
So much for those who sometimes think we have discovered all there is to know in physics. Every now and then nature shocks us into humility.
It's almost funny. A few years ago we thought we pretty much "knew" what the large-scale behavior of the universe was. We thought the universe would either collapse in a Big Crunch under its own gravity, slow down to a grinding halt, or expand forever but always slowing down the expansion.
Nobody expected the bizarre surprise which was in store for us...
In 1998 two teams of astronomers trying to measure the rate of change of the rate of expansion expected to find that the expansion was slowing down. They just wanted to measure the deceleration. They used type 1a supernovas which not only are extremely bright but have the same intrinsic brightness everywhere. This allowed them to estimate their distance by their apparent luminosity, and their speed of recession by their red shift.
Fantastically, they found that the rate of expansion is accelerating.
Now we are looking for answers...
We'll probably concoct a theory to explain this, but I think there is no reason to think that whatever we conclude is the final answer. Who is to say that in a couple of decades or a couple of billion years scientists won't discover that another effect actually will collapse the universe after all?
Einstein thought the universe to be static. To prevent it from collapsing under its own gravity a repulsive force would be needed. Enter his cosmological constant. We could say it is a sort of fudge factor which he arbitrarily introduced to make the universe static.
We now know the universe is expanding. We think that, right after the Big Bang, there was a period of rapid inflation and then it settled down to a more leisurely rate of expansion.
But everyone thought the rate of expansion would be slowing down, although we didn't know if it would expand forever or eventually implode. It was "obvious" that the gravity of all the matter and energy in the universe would slow it down.
Nothing is set in stone but various other explanations aren't cutting it. Some propose that intervening dust could make these exploding stars seems dimmer than they are, but no evidence of dust has been found. Others think that the quantum mechanical vacuum energy might explain what's happening, but the calculations yield 120 orders of magnitude more energy than needed. This means the universe would be ripped apart by such a force.
But where the heck did the universe suddenly come from???
Some have theorized that the universe came from nothing. Some sort of quantum oscillation allowed by the Uncertainty Principle. Perhaps it'll go back into nothing. I guess given enough time anything can happen.
But you know what? I think "NOTHING" means "NOTHING". There would be no such thing as Uncertainty Principle to begin with. No laws, no space, no time,...NOTHING!
Nothing except... Mathematics?
I think it's very difficult to grasp the concept of nothingness. Within our flawed human logic it seems impossible to have a universe spring from true nothingness. So the other alternative is that there has ALWAYS been SOMETHING.