[…] Our observable Universe caps out at about 92 billion light-years in diameter, less than a thousand times as large in all directions as our previous scale. It contains some 1080 atoms, clumped together in maybe a trillion galaxies, each with typically hundreds of billions of stars. But one of the most remarkable things about the Big Bang is that all of this, some 13.8 billion years ago, was once contained in a very small region of space, a region much smaller than our Solar System is today!
The thing that you might immediately wonder is whether there’s more Universe beyond the part that’s observable to us today, and — if so — how far does it go on? And what does it look like? And what are the physical laws in that part of the Universe?
Based on our observations of everything we’ve been able to see, from stars to galaxies to the leftover glow from the Big Bang to the matter in intergalactic space, we can learn some amazing things.
The part of the Universe that’s unobservable to us — filled with more planets, stars, galaxies, clusters and voids — is at least 150 times the size of the part that is observable! The fundamental constants look to be the same at all locations and at all times in our observable Universe, and our true Universe appears to be at least many millions of times the volume of the part we can see.
All of this, too, began in the same Big Bang that created all the matter-and-radiation in our hot, dense expanding Universe some 13.8 billion years ago. But that wasn’t even the very beginning.