Apr 18, 2025 05:56 PM
(This post was last modified: Apr 18, 2025 06:00 PM by C C.)
Is our Universe fundamentally unstable, and will it decay?
https://bigthink.com/starts-with-a-bang/...-unstable/
EXCERPTS: There are certain properties about the Universe that for better or worse we take for granted. The laws of physics, we presume, are the same at other locations in space and other moments in time as they are in the here-and-now. The fundamental constants that relate various physical properties of our Universe are assumed to truly possess the same, constant value at every time and place. The fact that the Universe appears to be consistent with these presumptions — at least, to the limits of our observations — seems to support this view, placing great constraints on how much it’s possible these various aspects of reality have evolved.
Wherever and whenever we can measure or infer the fundamental physical properties of the Universe, it appears that they do not change over time or space: they are the same for everybody. But earlier on, the Universe underwent transitions: from higher-energy states to lower-energy ones. Some of the conditions that arose spontaneously under those high-energy conditions could no longer persist at lower energies, rendering them unstable.
It’s important to recognize that unstable states all have one thing in common: they decay. And in one of the most terrifying realizations of all, we’ve learned that the fabric of our Universe itself may inherently be one of those unstable things as well. Here’s what we know, today, about how precarious our continued existence is.
[...] It had long been assumed, although it was untested, that because we do not know how to calculate the energy inherent to empty space — what quantum field theorists call the vacuum expectation value — in any way that doesn’t yield complete nonsense, it probably all just cancels out. But the measurement of dark energy, and that it affects the expansion of the Universe and must have a positive, non-zero value, tells us that it cannot all cancel out. The quantum fields permeating all of space give a positive, non-zero value to the quantum vacuum.
[...] Now, here’s the big question: is the value that we’re measuring for dark energy, today, the same value that the Universe recognizes as its “true minimum” for the contributions of the quantum vacuum to the energy density of space?
If it is, then great: the Universe will be stable forever and ever, as there’s no lower-energy state for it to ever quantum tunnel into.
But if we’re not in a true minimum, and there is a true minimum out there that actually represents a more stable, lower-energy configuration than the one we currently find ourselves (and the entire Universe) in, then there’s always a probability that we’ll eventually quantum tunnel into that true vacuum state.
This latter option, unfortunately, is not so great. The vacuum state of the Universe, remember, depends on the fundamental laws, quanta, and constants that underlie our Universe. If we spontaneously transitioned from our current vacuum state to a different, lower-energy one, it isn’t just that space would now take on a different configuration. In fact, by necessity, we’d have at least one of:
Wherever the quantum vacuum transitioned from this false vacuum state into the true vacuum state, everything that we recognize as a bound state of quanta — things like protons-and-neutrons, atomic nuclei, atoms, and everything that they make up, for example — would immediately be destroyed. As the fundamental particles that compose reality rearrange themselves according to these new rules, everything from molecules to planets to stars to galaxies would come undone, including human beings and any living organisms.
[...] Even with the Universe expanding, and even with that expansion accelerating due to dark energy, if a vacuum decay event such as the one envisioned here occurred anywhere within 18 billion light-years of us, at present, it would eventually reach us, destroying every atom at the speed of light in a Ghostbusters-level event when it did... (MORE - missing details)
https://bigthink.com/starts-with-a-bang/...-unstable/
EXCERPTS: There are certain properties about the Universe that for better or worse we take for granted. The laws of physics, we presume, are the same at other locations in space and other moments in time as they are in the here-and-now. The fundamental constants that relate various physical properties of our Universe are assumed to truly possess the same, constant value at every time and place. The fact that the Universe appears to be consistent with these presumptions — at least, to the limits of our observations — seems to support this view, placing great constraints on how much it’s possible these various aspects of reality have evolved.
Wherever and whenever we can measure or infer the fundamental physical properties of the Universe, it appears that they do not change over time or space: they are the same for everybody. But earlier on, the Universe underwent transitions: from higher-energy states to lower-energy ones. Some of the conditions that arose spontaneously under those high-energy conditions could no longer persist at lower energies, rendering them unstable.
It’s important to recognize that unstable states all have one thing in common: they decay. And in one of the most terrifying realizations of all, we’ve learned that the fabric of our Universe itself may inherently be one of those unstable things as well. Here’s what we know, today, about how precarious our continued existence is.
[...] It had long been assumed, although it was untested, that because we do not know how to calculate the energy inherent to empty space — what quantum field theorists call the vacuum expectation value — in any way that doesn’t yield complete nonsense, it probably all just cancels out. But the measurement of dark energy, and that it affects the expansion of the Universe and must have a positive, non-zero value, tells us that it cannot all cancel out. The quantum fields permeating all of space give a positive, non-zero value to the quantum vacuum.
[...] Now, here’s the big question: is the value that we’re measuring for dark energy, today, the same value that the Universe recognizes as its “true minimum” for the contributions of the quantum vacuum to the energy density of space?
If it is, then great: the Universe will be stable forever and ever, as there’s no lower-energy state for it to ever quantum tunnel into.
But if we’re not in a true minimum, and there is a true minimum out there that actually represents a more stable, lower-energy configuration than the one we currently find ourselves (and the entire Universe) in, then there’s always a probability that we’ll eventually quantum tunnel into that true vacuum state.
This latter option, unfortunately, is not so great. The vacuum state of the Universe, remember, depends on the fundamental laws, quanta, and constants that underlie our Universe. If we spontaneously transitioned from our current vacuum state to a different, lower-energy one, it isn’t just that space would now take on a different configuration. In fact, by necessity, we’d have at least one of:
- a different set of physical laws,
- a different set of quantum interactions that could occur,
- and/or a different set of fundamental constants.
Wherever the quantum vacuum transitioned from this false vacuum state into the true vacuum state, everything that we recognize as a bound state of quanta — things like protons-and-neutrons, atomic nuclei, atoms, and everything that they make up, for example — would immediately be destroyed. As the fundamental particles that compose reality rearrange themselves according to these new rules, everything from molecules to planets to stars to galaxies would come undone, including human beings and any living organisms.
[...] Even with the Universe expanding, and even with that expansion accelerating due to dark energy, if a vacuum decay event such as the one envisioned here occurred anywhere within 18 billion light-years of us, at present, it would eventually reach us, destroying every atom at the speed of light in a Ghostbusters-level event when it did... (MORE - missing details)
