An argument I hear a lot is that the Big Bang is the process of something coming from nothing, and therefore can't be correct. There are several problems with this view, not the least of which is exactly what the nothing actually consists of.
First of all, whatever existed "before" the first few seconds of our universe, let me warn you that prepositions don't apply. Before, after, during, below, behind, etc., because whatever it was, it didn't have space or time to describe it. To the best of my admittedly shallow knowledge on the topic, we don't know what it was. It wasn't nothing, that's fairly certain, but at the same time, nothing exists now that even comes close- everything we know exists in our universe, but we are talking about the origin of that universe. Everything that ever has or will exist, at least in a rudimentary sense, existed in the singularity*. What it exists "in" is likely unfathomable by even our greatest minds. This is because the terms we must use to describe it don't apply- it is simply our language, or our minds, failing us. How can we assign a time to a time when time was irrelevant and a location where places didn't exist?
How do we know about the big bang? Well, there's a lot to that question. One of the best forms of evidence we have is the red shift of the rest of the universe. There are literally billions of galaxies all around us- and they are all moving away from us. Think about ripples in an infinite pond- if we watch them long enough, we can deduce where the pebble initially hit. It's the same thing with galaxies- and they all point to the same place. If you want to know more about how we know this, google the Doppler Effect. I could ramble about it for hours.
Consider the degree of evidence, here- billions of galaxies to measure, and every one checked fits into a neat little one inch formula. And they all point back to a single instant in time, a single point in space, a single event in space-time.
Space-time is another fascinating topic, and important to understanding the difference between "something from nothing" and "something from nothing you can even imagine". Consider this. You and I are walking along an old train track. I see something shiny off in the grass and run off, let's say 50 meters into the grass. You're standing on the tracks waiting to see what I procure, facing me. Then something happens. Two lightning bolts strike. One strikes 25 meters behind you (A), and one strikes 25 meters between you and I (B). You see A and B, and hear them, simultaneously. But I see B as happening a fraction of a second before A. Which of us is right? Well, both.
Simultaneity, in other words, the times of events that occur relative to each other, is also relative to the observer.
Another example that may be easier to grasp is this: open a new document in a word processor. Now, copy this blog and paste it into the document. OK, consider this your singularity. Now, in MS Word**, open the find and replace dialog, type ? in the find box and in the replace box type "^&^l", without the quotes. Check use wildcards underneath and then hit replace all. This is the equivalent of typing return after every character in the document. You can keep hitting replace all, it just keeps getting bigger and bigger (after 1 time, I was up to about 70 pages- twice and it went to 200+). The striking thing about this is that the information stays the same, but space expands to match it. This is what the universe did, kick-started by dark energy. Consider the replace all button dark energy.
To quote J. B. S. Haldane, "Now my own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose."
*It's entirely possible that there wasn't so much a singularity as there was the observable portion of our universe compressed (or unexpanded) into a tiny size. We do know the universe is much larger than we can see, we just don't know how much.
**I'm sure a similar method exists in OpenOffice or Word Perfect, I just don't have them installed on my computer.
Now playing: Disturbed - "Another Way To Die" Lyric Video