Is stringy physics capable of saving the cosmos from a cataclysmic transformation?

Our cosmos might be inherently unstable. The vacuum of space-time may find a new ground state in an instant, sparking a catastrophic alteration of the universe's mechanics. Or not. String theory-inspired research suggests that our universe may be more stable than previously imagined. The cosmos suffered a series of dramatic phase shifts within the initial microseconds of the Big Bang. The four natural forces of electromagnetism, gravity, the strong nuclear force, and the weak nuclear force were formerly combined to form a single force. Physicists do not know the nature or behavior of this force, but they do know it did not persist long.


As the cosmos expanded and cooled, gravity initially separated from the remaining three. The powerful nuclear force thereafter became self-sufficient. Finally, electromagnetism and the weak nuclear force were the final two forces to divide. That final splitting is really within experimental reach: we can reproduce the circumstances of the early cosmos and acquire the energy required to (briefly) reunite those two forces within our greatest particle accelerators. Everything has been quite stable since then. The four natural forces have remained the four natural forces. Nuclei, atoms, and molecules were formed from fundamental particles. Stars eventually formed, and planets sprang from their ashes. In comparison to the initial few microseconds of the Big Bang, the last 13.8 billion years have been completely uninteresting.


However, the universe's seeming stability owing to its great duration may be an illusion. Each phase change that happened in the young cosmos totally rewrote the nature of reality, wiping away the old order and introducing new forces and particles. By measuring the mass of the Higgs boson, scientists may assess the current stability of the vacuum of space-time. The Higgs boson pervades all of space and time and performs a critical function. It not only provides mass for numerous basic particles, but it also acts as a wedge between the weak nuclear force and the electromagnetic force. In other words, the Higgs remained in the background during the early, hot, dense cosmos, allowing the two forces to combine. The Higgs grew stronger and separated the two as the cosmos cooled. (What mechanism separated the other forces of nature is a current area of study in contemporary physics.)

The cosmos is obviously not unstable; otherwise, it would have changed to a new reality long ago. However, the mass of the Higgs can tell us whether the cosmos is entirely stable or just metastable, which means it is stable for the time being until something produces a random phase shift. Current Higgs mass measurements show that we are on the verge of a new phase transition: the universe looks to be metastable and might tip over at any time. To suggest that a phase transition to a new ground state of space-time vacuum would be disastrous is an understatement. A random quantum fluctuation might induce the phase change at any time. It would then spread like an inflating soap bubble from there. Life and the cosmos would continue as usual outside the bubble. However, once within the bubble, a totally new set of physical rules would emerge.


Given that our entire existence is dependent on the stability of nature's rules, the arrangement of forces, and the menagerie of known particles, if the phase transition swept over us, we would just... vanish.


Or not. After all, this is all extremely speculative physics. A recent report released to the preprint archive arXiv offers a slightly more hopeful picture. Our understanding of physics is limited. Because of our work with the Higgs, we now understand how the electromagnetic and weak nuclear forces interact. However, scientists have yet to discover a consistent, coherent theory explaining how the strong nuclear force interacts with the others. A fully unified force, with gravity included in a thorough quantum explanation of nature, is well beyond our comprehension. String theory, on the other hand, is one effort to bring all of the forces together under a single framework. String theory views the underlying components of our existence as a collection of microscopic, vibrating threads.


While string theory is not yet complete (and some say that it will never be), it does allow academics to create tools for studying difficult topics, such as the physics of the phase transition that might destroy the universe. The authors of the new research investigated a form of string theory with nonlocal effects, which implies that strings in one region of space might appear to impact strings in another region of space despite their distance. (If you're wondering how far-fetched this is, consider that quantum entanglement is also a nonlocal phenomena.)


When the bubble grew, the nonlocal effects in this form of string theory tended to smooth out the bubble wall, according to the researchers. The bubble wall became so stretched out in some cases that it totally disintegrated. That is, if our reality was metastable and went through a random phase transition, the underlying stringy physics of the universe would prevent the phase transition from enveloping the entire universe; the bubble would explode before it could extend beyond tiny scales. This is still very speculative physics, but it can bring some solace while we continue to learn about the underlying workings of the world.

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