Before the Big Bang? a new study (Origins)

by David Turell , Wednesday, January 31, 2024, 17:39 (87 days ago) @ David Turell

Involves a magnetic field and a false vacuum:

https://mail.google.com/mail/u/0/#inbox/FMfcgzGwJvnTGKrrQvzpmpxMBqGCwCJM

"So far, this has all been theory. But a new experiment has now for the first time observed that quantum fluctuations can actually trigger a transition like that, luckily not for the entire universe, but for a small and safe test-setting in the laboratory with ultracold gases.

"You’d think that empty space is about as boring as it gets. But the question of just what it means for space to be empty is more difficult than you might think. You see, physicists believe that our entire universe was in some sense created from empty space. And if the empty space which we find around us now is not a true but a “false vacuum”, then it will eventually decay, too.

"These vacuum decays are similar to phase transitions that we can observe in nature around us.

"A good example of such a phase transition is chemical handwarmers like this one that I dug out of my children’s room. These handwarmers contain a liquid which is supercooled with a thin metal plate in it. That it’s supercooled means that it’s at a temperature below its freezing point, yet it isn’t a solid.

"Such a supercooled liquid contains energy that it wants to release by switching into another more stable solid state. You can trigger this transition by a large enough perturbation, for example pressure or a small electric spark by twisting this metal plate. The liquid then suddenly makes a transition to a solid, and the energy is released. This makes it warm up, which is why the thing is used as a handwarmer.

***

"Normally such phase transitions are caused by external forces. But theoretically they can also happen by quantum fluctuations in which case the system tunnels from the metastable to the stable state. These quantum fluctuations need no external cause. They just happen all by themselves.

"And this is one of the theories for how our universe might have been created with all that stuff in it. Once upon a time there was a false vacuum. It decayed and released a lot of energy that energy turned into matter. Some billions of years passed and now there’s us, the leftovers of that energy from the false vacuum.

***

"All of this is theory, mathematics equations. So far no one has actually seen a quantum fluctuation trigger such a phase transition or a bubble nucleation. And this is now what the new paper is about.

"They didn’t look at vacuum decay, but a phase transition triggered by quantum fluctuations and the bubble nucleation. For this they used a cloud of sodium atoms cooled to near absolute zero and put it into a magnetic field. The sodium atoms have spins, and they want to align themselves along the magnetic field. They also want to align themselves towards each other though. This creates a metastable state in which the atoms are all aligned in the same direction but not ideally aligned with the external field. Increase the strength of the external field and they’ll start flipping. They don’t flip on the borders because the magnetic field is weaker there.

***

"What does that mean? It means they have confirmed that these theories of quantum triggered phase transitions are correct and they also measured the dependence of the probability of the decay as a function of the energy. They’re now planning to do more experiments."

Comment: from a Hossenfelder video. Physicists hate 'something from nothing'. So, they invent possibilities. Note they used a magnetic field to influence the atoms. False vacuum is one invention and magnetic field another. That they could setup their experiment and succeeded only shows what works in the current universe. Guth et. al. showed we have no idea about the 'before', the first entry in this discussion.