The Birth of the Universe
In The Beginning
Space has always fascinated me because it reminds me how much more there is besides little ol' me on this world of ours. And boy is it beautiful as seen in the picture above. This article was inspired by an article that popped up on my screen from Live Science.
The photo above is an artist's depiction of what the Big Bang, how science thinks we came into existence, might have looked. In science and in logic, one of the ways to prove something is true, is to demonstrate the opposite cannot be true. (It is really more difficult than that, but will do for starters.)
The Big Bang theorizes that everything we know and can observe to as well as all that we don't know or are able to observer started out as a "singularity"1 in time and space. The attached article supposes that "we" began about 13.8 billion years ago, give or take. and that the size of the universe was the size of a peach that was 1 trillion degrees hot (doesn't make much difference if we are talking about Fahrenheit, Celsius, or Kelvin at that scale)
Others take that beginning back about 3 minutes earlier when everything, literally everything, was tucked into an infinitely small space which, for some unknown reason, exploded. I have covered in other hubs what happened in the nanoseconds, minutes, and hours after this "big bang". Here, I want to explore why there can't be any other explanation, even though the details are still being worked out.
1 a point at which a function takes an infinite value, especially in space-time when matter is infinitely dense, as at the center of a black hole.
The Infinite Universe
If the Universe didn't start with the Big Bang, what are the alternatives? One possibility is that the universe has no beginning and time has no beginning. Another might be there was a pre-universe that collapsed on itself into a singularity which then exploded and produced us. A third is that a god of some sort created everything out of whole cloth and a good imagination. Besides these three, there aren't too many, if any, other possibilities are there?
We can set aside the third possibility because it is not provable through testing (which any theory must be able to do to remain viable). The concept of god is a matter of faith, not science. So let's move on to the first possible alternative - we, writ large, have always been here. This is one of the topics on the Live Science article.
We know a few things to help us out here. We know light, photons shooting around in space, have a speed limit. We know through observation the galaxies and stars are moving away from each other right now. We know stars come and go every few billion years or so. Given this, let's think about what we might see in the night sky IF there was no beginning and time is infinite.
Assume that stars are being born, emitting light, and then dying. Assume further that this has been going on ... well ... forever. And finally, assume that space has no boundary. Now pick a direction to look, what is the probability you will see a star?
The answer is - almost 100%. Why? Assume you are focused on a point one light-year away. There is going to be some extremely small probability that that a star is,or was there. Now pick a point two light-years away. Now three, now four, and so on and so on. Since the universe is infinitely big, then there are an infinite number of small probabilities added together that give you a total probability of seeing a star - at any point in time. The sum of an infinite number of finite probabilities must approach 1 or 100%. Bottom line - you are going to see a star.
Now move your head a fraction of a degree and look again. Guess what? Another star. Move your gaze one more time and now you are looking at yet a different star. The point is, in this scenario, no matter where you look you will see a star. As a result, the night sky must end up being a glow rather than points of light.
But what do we observe? Points of light. This fact mitigates against the possibility that the Universe is infinitely big and infinitely old.
So How About a Bouncy Universe?
This one is a little harder to crack. An expanding and contracting universe would at least explain the Big Bang theory because once a previous universe collapsed on itself, what are you left with? A singularity all set to explode again.
This theory was quite popular because it helped explain, to some degree, what was "before" the Big Bang (until a few years ago that is)? What was before? Another universe of course. Even still, you have the ultimate problem, what came before the first universe? (Who the hell knows.)
Einstein's Theory of General Relativity is not specific as to whether the universe is ever expanding at an expanding rate, ever expanding at an ever decreasing rate2, cyclical (big bang-big crunch, or steady-state. What ultimately happens depends on the results of observing how dense the universe is.
To determine density you have to consider four things (which we won't go into any detail, thankfully): 1) known energy, 2) known matter, 3) dark matter, and 4) dark energy. "Dark" matter and energy are interesting because even though you can't see or feel them (at least until recently) they must exist in order to make mathematics we think are correct work.
Of course, just because they are needed doesn't make them so. Consequently, much scientific energy is being spent trying to prove or disprove the existence of these "dark" substances. At this point in time, the evidence is very conclusive about the reality of dark matter; while they can't see it, they can see the effect of it.
What is still being questioned is dark energy, supposedly the largest, by far, component of the universe. While the jury is still out, evidence is mounting pointing toward dark energy being all around us.
All of the observations to-date are pointing strongly to a universe whose density is such that our universe will keep expanding at an ever increasing rate, never to return to its beginnings.
2 If you walk toward a wall and each step you take is 1/2 the distance between you and the wall, you always get closer to the wall, but never reach it.
Has the Universe Changed Over Time?
For alternatives to the Big Bang to be true, the universe could not have been insignificantly small and immensely dense. One of the outcomes of this scenario, given today's known Universe, is that there would be evidence of change; first it was small and now it is big. Other alternatives more than likely cannot have evolved this way, especially if the scenario is that time and space are infinite.
So what evidence, if any, is there that the universe is different today than it was 13.8 billion years ago? The answer is Quasars, quasi-stellar radio source, discovered in the 1950s. Quasar's were very distant but uncommonly bright, active galaxies. The key is here is the "were" part. You see, if we are talking about some sort of static universe, we would see there "are" somewhat close and uncommonly bright active galaxies.
When astronomers look out to the sky what don't they see? You guessed it, Quasars
All of the science we have to-date point toward the picture you see above. An ever expanding universe where stars come and go with the distance between galaxies ever growing. Current theory has us beginning with the Big Bang from a singularity that contained the plan for the Universe, including the mechanisms for probabilistic outcomes that lead to two interesting phenomenons. One is an "almost" but not quite deterministic material universe and human "free will".
The end-state is a bit depressing, however. If the current theory and entropy holds, our universe will become ever more less energetic (fainter as it were) as its density approaches, but never reaches, zero.
Even though it may seem there will be almost nothing left eons from now, there is no reason why our progeny still won't be around. Granted, Earth will be incinerated in about five billion years, there is no reason not to believe we will have figured out how to jump to another, newer galaxy by then, and then another, and then ....