Some people dream of making babies, others dream of creating baby universes. Seriously? Yes, seriously. How is that supposed to work? What does it take to create a new universe? And if we do one, what do we do with it? That’s what we’ll talk about today.
At first glance, it seems impossible to create a new universe, because where would you get all that stuff if not from the old universe? But it turns out you don’t need a lot of stuff to create a new universe. And we know that from Albert Einstein. Yeah, the guy again.
Firstly, Albert Einstein taught us, as is well known, that mass is actually only one type of energy, E is mc square and so on. But more importantly, Einstein also taught us that space is dynamic. It can bend and curve and it can expand. It changes over time. And when the space changes over time, the energy is not preserved. I explained this in more detail in a previous video, but here’s a quick recap.
The simplest example of energy failure is the cosmological constant. The cosmological constant is the reason that the expansion of our universe is getting faster. It has units of energy density – that is, energy per volume – and, as the name suggests, is constant. However, if the energy per volume is constant and the volume increases, the total energy increases with the volume. This means that in an expanding universe you can get a lot of energy out of nowhere – if you only manage to expand the space fast enough. I know that sounds completely crazy, but that’s how it works in Einstein’s general theory of relativity. Energy is simply not saved.
So, okay, we don’t need a lot of matter, but how do we create a baby universe that is expanding? Well, you are trying to create conditions similar to those that created our own universe.
There is a little problem with that, namely that no one really knows how our universe was created in the first place. There are many different theories for this, but none of them have observational support. However, one of these theories has become very popular among astrophysicists, it’s called “eternal inflation” – and while we don’t know it’s right, it might be right.
In perpetual inflation, our universe arises from the breakdown of a false vacuum. To understand what a false vacuum is, let’s talk first about what a true vacuum is. A real vacuum is in a state of minimal energy. You can’t get energy from it, it’s stable. It just sits there. Because it already has minimal energy, it cannot do anything and you cannot do anything with it.
A fake vacuum is one that temporarily looks like a real vacuum, but eventually breaks down into a true vacuum because it still has energy left and that extra energy flows into something else. For example, if you throw jelly on a wall, it will stick there for a moment, but then it will fall off. That moment when it sticks to the wall is like a false vacuum state. It’s unstable and eventually breaks down into the true vacuum when the jelly falls to the ground and the extra energy splatters it all over the place.
What does this have to do with the creation of our universe? Imagine you have a lot of false vacuum. In this false vacuum there is a stain that breaks down into a true vacuum. The true vacuum has lower energy, but it can have higher pressure. When it has a higher pressure, it expands. This is how our universe could have started. And in principle, you can recreate this situation in the laboratory. You “only” have to create this false vacuum condition. Then part of it crumbles into a true vacuum. And when the conditions are right, this true vacuum will expand quickly. As it expands, it creates its own space. It doesn’t grow into our universe, it makes a bubble.
This universe creation only works when you have enough energy or mass in the original blob of false vacuum. How much do you need? Depends on some parameters of the model that physicists do not know exactly, but in the most optimistic case it is about 10 kilograms. This is what it takes to create a new universe. 10 kilograms.
But how do you create 10 kilograms of false vacuum? Nobody has a clue. Plus, ten pounds might not sound like a lot if you’re a rocket scientist, but that’s a terrible amount for particle physicists. The mass equivalent with which even the largest particle accelerator at the moment, the large hadron accelerator, works is 10 to minus 20 grams. If you collide large atomic nuclei instead of protons, you can increase that by a few orders of magnitude, but 10 kilograms is nothing that high-energy physicists can do will work in my life. Nobody will create a new universe anytime soon.
But in principle we could do it theoretically. If you believe this story with the wrong vacuum and so on. Assuming for a moment that this is correct, what would we do with these universes? Would we potty her and send her to cosmic kindergarten?
Well, no, because unfortunately these little baby universes don’t stay connected to their mother universe for long. Their connection is like the neck of a wormhole, it becomes unstable and breaks in a split second. So they would give birth to these universes, they would grow, but then, blip, they are gone. From the outside, they would look like tiny black holes.
Incidentally, that could happen all the time without particle physicists doing anything. Because we don’t really understand the quantum properties of space. So some people think that space really makes a lot of quantum fluctuations. These fluctuations occur at distances so short that we cannot see them, but they could sometimes create one of these baby universes.
If you want to know more about this topic, Zeeya Merali wrote a very nice book on baby universes called “A Big Bang in a Little Room”.