The universe could vanish at any moment – why hasn’t it?

Cloud cosmology accepts an act of creation which shapes matter and introduces TIME.  Scaling decline induces Quantum.

Scale limits surely block the possibility of a BIG SLURP.  Recall that mathematical infinity does not exist in our empirical universe.  Any deep dive into quantum must run into this limiting factor.

By the way, the best evidence that this is right is the mere existence of gravity.

The universe could vanish at any moment – why hasn’t it?

A cataclysmic quantum fluctuation could wipe out everything at any moment. The fact that we’re still here is revealing hidden cosmic realities

By Miriam Frankel

19 November 2024

Kevin Lucbert

https://www.newscientist.com/article/mg26435180-800-the-universe-could-vanish-at-any-moment-why-hasnt-it

Billions, perhaps trillions, of years from now, long after the sun has engulfed Earth, cosmologists expect the universe will end. Some wrestle with whether it is more likely to collapse under its weight in a big crunch or keep on expanding forever into an infinitely empty big freeze. Others reckon our cosmic endgame will be decided by a mysterious kind of energy that shatters the universe in a big rip.

But there is a more immediate cataclysm that may already be barrelling towards us at the speed of light: they call it the big slurp.

The slurp in question starts with a quantum fluctuation that sets a bubble rolling across the universe like a cosmic tidal wave, obliterating everything in its path. We should take this possibility seriously, says John Ellis at King’s College London. In fact, it is less a matter of if this apocalypse will play out, but when. “It could happen while we’re talking,” he says.

Theorists like Ellis are actually surprised that such a catastrophe hasn’t already occurred in the observable universe. But rather than taking our precarious existence for granted, they are using the plain fact we are still here as a tool. The thinking is that there could be some exotic physics preserving us.

This kind of existential cosmology is even helping physicists filter through their myriad models of the universe, and could tell us how the cosmos began in the first place. “You may need something that stabilises [the universe], and it could be a new physics,” says Arttu Rajantie at Imperial College London.

Quantum fields are the fundamental building blocks of the universe, which then give rise to the more familiar particles and forces of the standard model of particle physics. Chief among them is the Higgs field, associated with the Higgs boson, which permeates the universe and gives elementary particles their mass.

The Higgs had been hypothesised for decades, but we were in for a surprise when the particle was finally measured at CERN’s Large Hadron Collider (LHC) near Geneva in 2012. The result suggested that the Higgs field isn’t stable because it isn’t in its lowest possible energy state. We know that objects like atoms or particles tend to want to minimise their energy, so in theory the Higgs could suddenly drop to its lowest possible state in a process known as a phase transition.

This is similar to the phase transition that occurs when liquid water boils to make steam. If you look inside a saucepan of near-boiling water, you will see tiny bubbles of gas nucleating at the bottom. Similarly, a phase transition in the Higgs field would create bubbles of its lowest possible energy.

These bubbles would contain very strange physics. As a bubble formed, the quantum fields inside would suddenly shift, effectively rewriting the laws of physics and creating chaos. Terrifyingly, the bubbles would expand at light speed, swallowing everything around them.

The appearance of this apocalyptic bubble comes down to chance. As an analogy, imagine the Higgs field is a ball at the top of a hill that has several valleys of differing heights beneath it. The ball could roll down into one of the higher valleys and stay there happily, while still not being at the lowest possible point. This is the situation the Higgs field is in now, which we call a “metastable state”. A ball in such a valley can’t roll out of it without a kick. But because this field conforms to the rules of the quantum world, it can mysteriously “tunnel” to a lower valley, or energy state. This is a quantum process akin to a ghost walking through a wall. We can make estimates for how likely the Higgs field is to do this in a given time period, but we can’t predict exactly when it will occur.

The stability of the Higgs field (or the shape of the valleys in our analogy) depends on the complex way that other elementary particles interact with it. Particles called bosons, which carry the fundamental forces, tend to make the field more stable. In contrast, particles known as fermions – the constituents of matter, such as quarks – make the field less stable, raising the risk of a phase transition.

Our precarious cosmos

Recent measurements of these particles at the LHC aren’t comforting. Aside from the Higgs itself, the heaviest known fundamental particle, called the top quark, has the greatest influence on the stability of the Higgs field. The heavier it is, the less stable the field is. In recent years, as measurements of the top quark mass have become more precise, it has become clearer that the Higgs is – according to the standard model – metastable. “The measurements are now so good that we pretty much know that we are in that metastable range,” says Rajantie.

Assuming there’s no mistake, the universe is doomed – we just don’t know when the big slurp will happen. Based on the shape of these valleys, it is likely to be in billions of years. But it could be tomorrow.

What we do know is that we are still here. That is proving a useful insight for physicists weighing up the many models of the cosmos that proliferate today, says Rajantie. Some invoke unproven entities that could spark a catastrophic phase transition, while others may be keeping us hanging in the balance.

In particular, strong gravitational fields can “seed” the Higgs field, making it more likely to transition sooner rather than in billions of years’ time. “When you’re boiling water, if there are any impurities in the water, then that’s where the bubbles tend to form,” says Rajantie. These triggers include cosmic strings and other defects in space-time. Black holes, which are so massive that not even light can escape, are also good candidates to seed the Higgs field and provoke the big slurp.

Primordial black holes

Some black holes are better at seeding than others. In 2014, theorists including Ruth Gregory at King’s College London and Ian Moss at Newcastle University, UK, calculated that since smaller black holes have a larger space-time curvature at their outer edge, they are more likely to provoke a phase transition. The gravitational field of these small black holes is concentrated in a tiny point, rather than spread out as in the case of a supermassive black hole. Small black holes “seem a lot more likely to cause the end of the universe”, says Moss.

Indeed, it is the tiniest black holes, called primordial black holes, that we should fear the most. Although they have never been directly detected, primordial black holes are often included in cosmological models – added to explain dark matter, for instance, or the origin of supermassive black holes. They are thought to have formed when extremely dense clouds of plasma in the early universe collapsed.

Our continued existence is an argument for why primordial black holes can’t exist

Like all black holes, primordial black holes evaporate by emitting radiation. But the diminutive size of primordial black holes means they emit radiation more quickly and create “hot spots”, which have a much higher temperature than the surrounding space. This higher temperature could provoke a phase transition bubble, as the Higgs field is more likely to receive a thermal kick that pushes it out of one valley into a lower, more stable valley, according to research published in September by Lucien Heurtier at King’s College London and his colleagues.

In fact, because smaller black holes have stronger gravitational fields at their outer edge, primordial black holes get more dangerous as they evaporate. “It means that the risk for a Higgs phase transition increases with time,” says Heurtier. Our continued existence, he says, is an argument for why primordial black holes can’t exist and why cosmological models built on them should be scrapped too.

Primordial black holes are among the most likely candidates to seed a bubble that rewrites the laws of physics

There is, however, an alternative explanation for why the Higgs field hasn’t transitioned. Despite the precise measurements of the top quark and the Higgs boson, we can’t be certain that the Higgs is in a precarious metastable state after all. It might be that there are unknown particles and forces stabilising the Higgs field in a way that protects us from the big slurp. “If there’s some other particle that comes into play at some higher energy, then that will change the story again – we just don’t know yet,” says Katy Clough at Queen Mary University of London.

For example, a hypothesis called supersymmetry posits that every particle we know of has a much heavier “superpartner”, and if these really exist, they would have a stabilising effect on the Higgs field. However, so far, the LHC has failed to find any evidence for these superpartners. “Supersymmetry is one way of avoiding the problem – the Higgs field metastability is a pro-supersymmetry argument,” says Ellis. “I retain my enthusiasm for supersymmetry, but I am somewhat disappointed that my love for it hasn’t been requited yet.”

The alternative, he says, is to resort to “special pleading” arguments, whereby most of the cosmos already flopped into its lowest-energy state, but a few regions, such as ours, were left in a metastable state on the brink of collapse. In this view, a metastable state is necessary for life, so we must find ourselves living in one of these precarious patches.

Quantum gravity

In the absence of direct evidence of new particles, Rajantie thinks we should investigate what we can learn about cosmology if we just assume the Higgs field is metastable. He is using this supposition to weigh in on models of quantum gravity, which seek to unify quantum theory with general relativity, the two central pillars of modern physics.

For example, we don’t know exactly how the Higgs field and gravity affect each other in these models. Physicists describe this interaction with a parameter called non-minimal coupling, but it is complicated to determine because the Higgs and gravitational fields are so different in nature. Neither can we measure it, because gravitational fields in the universe today are so weak.

But Rajantie has used our cosmic existential crisis to focus in on the strength of this parameter by eliminating the impossible. We know the parameter can’t be negative; if it were, the Higgs field would be so unstable that it would have triggered a phase transition during inflation – a sudden period of rapid expansion early in the universe’s history – which clearly didn’t happen. And if the parameter is greater than 10, then the phase transition would have been triggered at the end of inflation. “We can say that it must be between 0 and 10 because otherwise the universe would not have survived inflation,” says Rajantie. Many current models of quantum gravity are in line with this, he says, suggesting they are on the right track – and any new models put forward must follow suit.

It is incredibly likely that a catastrophic bubble has already happened and it just hasn’t reached us yet

We should take heart that the big slurp doesn’t seem to have occurred in the universe’s ancient past. Back then, there was a lot more energy around to kick the Higgs field into a deeper valley, making a phase transition more likely to occur in a given time period, says Rajantie. In that sense, our cosmos making it to the ripe age of 13.8 billion years old is something to celebrate. “Today, it’s very difficult to achieve a phase transition due to relatively low energies,” he says.

But for this same reason, Rajantie believes a bubble has probably already been created somewhere, just not within our visible universe. “It is incredibly likely that it has already happened in the early universe and it just hasn’t reached us yet,” he says. Where in the vast expanse of the unobservable universe this might have happened is anyone’s guess – leaving us, once again, in the dark about when our time might be up.

Superfluid universe

Faced with uncertainties like these, existential cosmologists are eagerly awaiting the results of an experiment at the University of Cambridge that Moss and Gregory are involved with. Excitingly, this experiment aims to create a laboratory analogue of a universe phase transition, which could help researchers refine their ideas about what is most likely to cause the big slurp.

That’s because the equations describing a quantum phase transition in the universe can, in some circumstances, be equivalent to those describing a phase transition in a kind of strange matter called a Bose-Einstein condensate, which consists of atoms at extremely low temperatures. The latter would also produce bubbles, effectively simulating a cosmic phase transition.

The experiment could even simulate a seeded phase transition, where the seed is an imperfection engineered in the system rather than, say, a real primordial black hole. Researchers would be able to explore the difference in the rates of bubble creation with and without seeds – potentially giving us a better idea of how much danger we are in.

Ultimately, how long we have left may be a matter of luck, says Ellis. Unless, that is, we accidentally provoke the Higgs field to transition in a particle collider experiment on Earth.

In 2019, Moss and Gregory calculated how particle collisions, either from cosmic rays or in experiments like the LHC, could create tiny back holes that seed a phase transition. For their part, they doubt experiments on Earth could push us over the edge, as these kinds of collisions were prevalent in the early universe and, as far as we know, didn’t cause it to end.

More research is required to be certain, though, says Moss. For example, when it comes to phase transitions, it is important to consider the area of the particles colliding as well as their energy. “We’re fine to collide protons [as we do at the LHC], but we know less about the effects of colliding very large nuclei,” he says.

But for all that the end of the universe depends on the whims of the Higgs, we may well owe our existence to it in the first place. Last year, Clough and her colleagues published research suggesting that quantum tunnelling effects could prevent a contracting universe from collapsing in a big crunch. In their model, this contraction squeezes a Higgs-like field in such a way that its lowest-energy state becomes negative. This would cause a collapsing universe to bounce outwards, creating a new, expanding universe perhaps not unlike our own.