Suppose a group of scientists was assigned the task of creating a video that depicted the big bang and the next billion years. they would be backing away from the core faster than it expanded. The video would be 1 hour long. How fast would they be backing away? I got something like 277,000 light years per second. Is something like this depict able?
The universe has no “core”. The horizon of what’s visible would still be centered around wherever “you” are at.
That is, the “Big Bang” happened everywhere, and is and was expanding equally everywhere, from every point. As far as we know.
I had no idea, I thought it started with something the size of a pea.
As for being depicatable, why couldn’t you always zoom it enough to keep it the same size in the viewing frame. It might end up looking pretty boring for most of the hour, because the changing scale would completely cancel out the expansion, but why couldn’t it be done?
That’s kind of the point. There was an age of the universe when everything, all together, the entire universe, was the size of a pea. But there’s no outside of it, at least not in the sense of a physical place you could get to from the inside of it.
They’ve done better than that - “A Journey To The End Of Time” (time lapse where the time scale doubles every 5 seconds, making it a practical demonstration of what “exponential speedup” really means).
As one commenter put it: “Huge respect for the cameraman who have recorded all these dangerous things for us to see”
Warning: It is about a half hour long and once you start watching it is very hard to stop.
I really enjoyed that
It’s kinda hard to wrap your head around the concept, but imagine that you are from flatland, where everything is 2-D. So the entire universe is like a big sheet of paper. You can go in the X and Y directions, anywhere along the surface of the paper, but there is no Z direction (up).
Now imagine that instead of a piece of paper, the universe is a balloon. But it’s not a 3-dimensional balloon. It’s a 2 dimensional balloon. So the balloon starts out small, and everything is close together. But then the balloon gets bigger and bigger. What point on the surface of the balloon is the center of the balloon? There isn’t one. All of the points are on the surface. This gets confusing, because we want to naturally think of the balloon as having 3 dimensions, but remember, this is 2-D. You can only go along the surface of the balloon. You can’t go inside the balloon and you can’t go up off of the surface. All you can do is go around the surface of the balloon.
The way they teach the Big Bang, people often picture all of the mass of the universe crunched up into a tiny ball. And then the ball explodes, sending all of the mass out into a 3-dimensional space that already existed. This is the point. That space did not exist. The space was all squished up into that ball too.
Looking at it another way might help. Imagine you take a flag, and you stick it at a point in space, and that flag never, ever, ever moves from that point. Now pick another point in space and put a second flag there. That flag also never moves. What you find is that the two flags move apart from each other, even though neither flag moves. The flags aren’t moving. The space in between them is getting bigger.
Now rewind that, back to the beginning of the universe. The two flags haven’t moved at all, but now they are squished down to the same point. Pick a spot 4 billion light years away. That’s also squished down to the same spot. Pick a point on Mars. That point is squished down to the same spot. Those points in space haven’t moved at all, but the points of space itself are all squished down to a single spot.
There is no core. There is no center of the universe. The point where you are was right next to every other point, and the points themselves expanded out, not just the bits of matter, but space itself.
Getting back to your video, wherever you stick your magic video camera, the entire universe expands away from that point. Put the camera where you are now, and the rest of the universe expands away from it. Put the camera somewhere near Alpha Centauri, and the rest of the universe expands away from it. It’s all points on the surface of a balloon, except in 3 dimensions instead of 2.
We tend to think of space as being fixed, like graph paper. The X and Y coordinates are fixed. But they aren’t. It’s better to think of it as the graph paper itself is stretchy. You can still count 3 squares over and 2 squares up on your graph paper, but the paper itself keeps getting bigger.
I’m sure I’m not the only one who checked that your post had occurred at least a half hour after peccavi’s. 
I am not even aware of that thread
I posted that on my facebook page and was getting likes in less than 5 minutes.
As I picture it, it’s just the known universe that was compressed down to the size of a pea. I could be wrong about this part, but if the universe is indeed infinite in space, then it couldn’t ever be anything but always infinite in size? But the density of space at T[sub]0[/sub] was infinitely dense, and the Big Bang is just the expansion of this density?
You understanding is correct, except it’s not the known universe but rather the observable universe. We don’t know how big he universe is, but it’s much bigger than the observable universe. Probably much bigger, perhaps even infinite,
Perhaps the main problem with understanding the BB is the name. It makes it sound like an explosion. It wasn’t one. Better names would be something like the Big Stretch or Big Expansion.
Unless you were a 4(physical) dimensional creature. Is that correct?
Not really. Where are these extra dimensions (which have not been detected) supposed to be, if not in the universe?
No matter how I try I can’t comprehend space not existing even if nothing else existed. Is science positive that space did not exist?
I doubt anyone today is “positive” how things work when space/time is infinitely dense.
ETA there have also been eternal inflation models…
That’s what the math says.
I generally think of it as if the universe is a piece of paper with stuff printed on it. The print is the matter of the universe; the whitespace is the space. Before the paper came into existence the whitespace didn’t exist either.
I also think of time as being tracked along the long axis of the paper, like frames on a roll of film; before the paper existed time didn’t exist either.
You can ask “where is the paper”, but there isn’t necessarily anything else surrounding the paper, or anything else preceding the paper. If you require such things then you’re just creating a surrounding theorized universe with its own space and timeline, and it ends up being turtles all the way down (until the turtles stop, and that universe has no surrounding area or preceding time).
In that video, they have the sun killing off all life on earth in just 1 billion years!:eek: I thought we had at least 4 times as long. As humans, we need to stop competing against each other and figure out how to get to, and live, elsewhere.