This is the best way the world ends: not with a bang, however with a quantum vacuum decay of the bottom state of the universe to its true minimal.
The universe underwent radical phase transitions previously. These transitions ultimately led to the division of the four fundamental forces of nature and the panoply of particles we all know immediately. All of that occurred when the universe was lower than a second previous, and it has been steady ever since.
But it may not final eternally.
A divided cosmos
To perceive the soundness of the universe, first we have to speak about phase transitions. Phase transitions are when a substance undergoes a speedy, radical transformation. They occur on a regular basis. You boil water, and it transforms from a liquid right into a gasoline. You cool that very same water, and it turns right into a block of ice.
Perhaps essentially the most unique phase transitions are those who occur to quantum fields. Quantum fields are the elemental constructing blocks of the universe. Every sort of particle — say, a photon or an electron — is basically only a native manifestation of an underlying area. That area soaks all of space and time like bread dipped in olive oil. The method these fields work together and talk with one another makes up the forces and physics of our existence.
That existence is predicated on 4 basic forces: gravity, the weak power, electromagnetism and the robust power. But it hasn’t at all times been this fashion. In the earliest moments of the cosmos, these forces had been united. As the universe expanded and cooled, the quantum fields underwent phase transitions, splitting aside one after the other.
The final phase transition occurred when the electromagnetic power cut up from the weak power. That splitting gave rise to the photon and the W and Z bosons, the carriers of these two forces.
Since that occasion, which occurred when the universe wasn’t even a second previous, the whole lot’s been steady — no extra splitting, no extra phase transitions. The 4 forces of nature went on to form and sculpt the evolution of the cosmos for billions of years.
As far as the whole lot appears to be like, it is all steady — for now, anyway.
Not so steady in any case
The stability of the universe is difficult to measure. Sure, it has been over 13 billion years since something as attention-grabbing as a phase transition has occurred. Yes, 13 billion years is a very very long time, however on this planet of quantum fields, something can occur.
Our finest guess at probing the soundness of the universe is thru the mass of the Higgs boson. The Higgs is a really attention-grabbing area; its presence within the universe is what separated the electromagnetic power from the weak power and what maintains that cut up immediately. Without the Higgs boson, these forces would merge proper again collectively.
In quantum physics, the extra large an entity is, the extra unstable it’s. Massive particles shortly decay into lighter ones, for instance. So, if the Higgs could be very large, it may not be as steady because it appears, and it’d decay into one thing else sometime. But if the Higgs is mild sufficient, it is doubtless to hang around eternally, and there is nothing extra to say about the way forward for the quantum fields of the universe.
Measurements of the Higgs have discovered that its mass places the universe smack in between the “really, honestly stable” and “Oh no, it looks a little unstable” regimes. Physicists name this state “metastable” — a scenario that’s steady for now however might shortly deteriorate if one thing had been to go mistaken.
Searching for stability
The obvious metastability of the quantum fields of the universe is a bit unsettling. Although it might imply that the universe might persist for billions, even trillions, of years with out something going mistaken in any respect, it might additionally imply that the universe is already starting to rework. All it will take is one little shake within the mistaken course, in some random patch of the universe, the place the Higgs falls aside and the underlying quantum fields discover a new, extra steady configuration. That area of “new” universe would then propagate outward at practically the speed of light by the “old” universe.
This sort of phase transition is named a “false vacuum decay.” It references the concept the vacuum of our universe is a “false” one — it’s not as steady as it’d seem, and it’ll sometime decay into one thing new.
By the time we obtained any info that the phase transition was upon us, it will already be taking place.
What can be on the opposite aspect of that new universe? It’s unimaginable to say. It is perhaps completely mundane, with the brand new quantum fields trying precisely just like the previous quantum fields and nothing amiss. It might be only a slight adjustment, like a bit tuning to the character of dark energy or a slight adjustment to the plenty of neutrinos. Or, it might be radically totally different, with a universe crammed with brand-new forces, fields and particles — which might make life (and chemistry and atomics) as we all know it unimaginable.
Of course, we’re not even 100% certain in regards to the metastability criterion. We know that the Standard Model of particle physics is incomplete. An entire model might rewrite our understanding of quantum fields and the place the “stable-unstable” line is drawn.
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