Hard to wrap my mind around this one. Anyone have any good analogies that fit?
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The incorrect conception is that there was this big void of “space” and somewhere in that void a big bang occurred which “threw” stuff out and created the universe.
The slightly more correct view is that everything including what we call “space” was created in the big bang. All that space did not exist prior to the big bang. There is no eternal space which was empty “before” the big bang and the big bang just filled it up with stuff. Time and space were created from a very small point which we call the big bang and that space itself inflated (as it continues to) over time. So everything that we experience including distance and time and all matter was created in the big bang.
Everything and everywhere was infinitesimally small.
Saying it started as a single point doesn’t make sense because there was nothing else.
Everything was contained within the big bang.
It’s a little better if you can see it.
But imagine a grid with a bomb in it. The bomb explodes at a point and goes outward. The grid doesn’t move. That’s bangs as we’re used to.
The big bang is more like a grid that’s so close together you can’t see any space between the lines, and the whole gridpaper is just chock-full of stuff. The grid explodes and the space between the lines gets bigger and all the stuff spreads out.
That’s the universe at about 1 nanosecond. The big bang is that scenario, just reversed by 1 nanosecond and all the grid lines aren’t just super-close, they’re on top of each other. Things get really trippy and our understanding of physics breaks down before the first picosecond (10^−12). “Everywhere” used to all be at the same point.
The thing that’s tricky about it is that we sort of can’t help but visualize it from the outside, looking at a tiny point that blew up and turned into stars and space and all that stuff, but the reality of the situation is that the perspective we’re imagining didn’t, and couldn’t, exist.
There was literally nowhere for us to “stand” to get this perspective. There was no “where” outside that tiny initial point. “Everywhere” was within some really tiny distance of everywhere else. So when that tiny point started expanding, it necessarily happened everywhere, because that’s all the “where” there was.
Hopefully that didn’t confuse you further.
There aren’t any great analogies, in the sense that none of the analogies you’re going to encounter are actually fully analogous. As human beings, we’ve never experienced in our lives anything even approximately accurate to what happened during the Big Bang.
The most straightforward analogy is the balloon analogy. Imagine you have a balloon and you use a Sharpie to put a tiny dot on that balloon. That dot represents the entire universe at the beginning of the Big Bang. Now imagine blowing up the balloon. The dot gets bigger. But it doesn’t get bigger from expanding away from a particular location. All of the little tiny ink particles in the dot are moving away from all of the other tiny ink particles and it doesn’t matter where you are in the dot at the beginning, you see the same amount of expansion as you’re blowing up the balloon. If you imagine sitting on top of one of these tiny ink particles, no matter where you are, all of the other ink particles you see are moving away from you at the same rate.
There are some flaws to this analogy, but I’m not going to mention them because it might actually make it easier for you to understand if I avoid pointing out some of the holes.
Neither is scientific. The only correct thing to say is that we don’t know beyond a certain era of time.
That said, one of the most accepted and evidence driven hypotheses that you are probably referring to is the inflationary epoch. This is not equivalent to the big bang, and the best ELI5 is assume many places in the universe have a bowl with a moving ball in them. For places where the ball jumped out of the bowl, the universe in that region of space expanded faster. In places where it didn’t, it expanded slower.
This happened after the big bang, but not super long after. We don’t have direct evidence of it, but it is theorized to involve an inflation field with properties like that ball in a bowl: as long as the ball remained in the bowl it was stable, but if it got knocked out however it did, it would never jump back in. This is in more advanced terms called a false vacuum state, and the ball falling out of the bowl went to the true vacuum state (the bowl being the false vacuum state, and the table it sits on being the true vacuum state).
It did happen at a single location, but since every thing in the universe was also at that location everything in the universe was in the big bang so the “debris from the explosion” is everywhere at once so from the point of view of the debris there is no single point of origin. In theory if you were to step outside the universe and able to observe it (how this would happen regarding speed of light is impossible to say) there would be a single location where it could be said to be spreading out from.
When you think of a bang you think of a dense cluster of matter and then all the chunks of matter flying away from their starting point. That is perfectly reasonable and makes complete sense in every single bang is like this in physical reality.
The Big bang had no bang. The name was a joke created by a man who hated the theory.
According to the standard model there was a time where how our universe had no volume and no matter. This cannot be proven because we can’t see that far back. The farthest back we can see is cosmic microwave background radiation. Everything else is modeled.
However, the background radiation itself gives you a good idea of what you are looking for. Before the cosmic microwave background radiation the entire universe was full of stuff and there was no point in the universe that was even remotely Empty. Energy was so packed together that it could not form stable atoms.
Picture an entire universe absolutely packed with a dense soup of energy. That is the Big bang theory at some point after the big bang moment.
Cosmic microwave background radiation happened when the density of all the stuff in the universe got sufficiently low so that if a stable atom formed it would not immediately be destroyed. The entire universe essentially went from ions to atoms and the photons that were still in transit. At that moment we’re not immediately reabsorbed by the ions and were therefore for allowed to continue to exist.
Those photons that existed right before the universe went transparent to photons, due to the universe being comprised of stable atoms rather than ions which absorb the photons immediately, are what we call cosmic microwave background radiation and this was the proof of the theory of the big bang.
So to answer your question, the reason you were having hard time picturing the big bang happening everywhere is because you were picturing a bang. Instead, picture the entire universe tightly packed with stuff and pictures of volume of the universe increasing over time without any change to the amount of stuff existing in the universe. That is the process of the expansion of the universe according to the Big bang theory.
According to the Big bang theory, the volume of the universe changes without real motion. So don’t picture a bang where anything moves instead. The mechanism of the big bang is that increase in volume. This is called metric expansion of space.
Another way to picture it which is much easier is to imagine the entire universe is the size it is now. Instead of metric expansion of space, we will have metric contraction of matter.
Imagine at the moment of the big bang at the Planck’s constant is infinitely large and therefore all particles are infinitely large. Now. Imagine all the particles in the universe shrinking over time.
At the start of this process the entire universe would be absolutely packed with stuff because everything takes up all the space. Over time the particles take up less space and at some point there is enough space in the universe for stable atoms to exist. As time continues and particles drink the atoms condense into galaxies and stars and whatnot and we get to the point we are today.
I offer this mental picture only because the concept of the volume of the universe increasing over time is more difficult than the concept of matter and particles shrinking over time.
Some explanations depend on different theories you might subscribe to. I personally prefer the dark energy, infinite cosmos explanation
Imagine a flat spacetime, accelerating almost infinitely fast in all directions. WAYYY faster than the speed of light. But because space is always fluctuating with energy, at some point it’s destined to pop open a bubble of energy somewhere. Then you take that 100% pure energy bubble that’s infinitesimally small and expand it by unbelievable magnitudes at breakneck speed. The universe was the size of a marble at around 10^-31 seconds and grew faster in ONE second than the following 14 billion years of cosmic expansion that followed it. And after that 1 second, it was still 100% pure energy. 100% full, at literal cosmic scales. That should give you an idea of just how much “stuff” there is. Because matter bends space, you get gravity, and then gravity helps slow down a lot of that expansion. But eventually dark energy wins over and expansion happens again. Not at inflation rates – that’s way in the future/past depending on how you view time.
Because spacetime now is accelerating in all directions, eventually our universe will result in “heat death” which is basically everything goes super far away from each other and everything just decays away as the universe keeps expanding and expanding faster and faster. We’re eventually left with an ever expanding flat universe with basically nothing in it – Which sounds awfully similar to our initial starting condition. Which is why I think it’s true. It’s just a cyclic model.
Maybe you can think about it like a balloon.
The balloon is space, and you blowing up the balloon is basically the big bang. It happens all over the balloon and expands it into a sphere, but the balloon started as basically a single small place, but that whole balloon is now entirety of space. In that way big bang happen all over the balloon.
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