Is the universe a stable quantum system?

September 10, 2014 by Brian Koberlein, One Universe at a Time

According to legend, when Damocles declared that his king, Dionysius, must have a posh and easy life, Dionysius offered to trade places with Damocles. There was only one catch. Dionysius decreed that a sword be suspended over the throne by a single horse hair, so that Damocles would always know the peril of being king. Since then the Sword of Damocles has come to represent a threat of doom that could strike without warning. While the prospect of living under a hanging sword doesn't seem pleasant, stories of impending doom are quite popular, particularly within popular science.

Every now and then some science news story will hit the press trumpeting the latest Damocles sword. Giant asteroid could wipe out life on Earth! Nearby supernova could kill us all! Solar flares could destroy civilization! Geomagnetic reversal! Rogue black holes! And on and on. The latest doomsday news to hit the press stems from a claim by Stephen Hawking that the existence of the Higgs boson means that the universe could spontaneously collapse at any moment. Game over, Man! Game over!

Like most such hype, the real story is both less sensational and more interesting. It all starts with a long-known property of quantum mechanics, that quantum systems don't always have to settle in their most stable configuration. They can instead find themselves in a locally stable state (known as a metastable state). We see this, for example, with electrons in an atom. The stable state of an electron in an atom is its lowest possible , but an electron can be in a higher energy level for a while. Eventually it can drop to a lower energy level, which releases a photon. This effect is why we see line spectra in stars and interstellar clouds.

With the discovery of the Higgs field, one question we can ask is whether the universe as a quantum system it is in a stable, low-energy state, or in a metastable higher energy state. According to the standard model of particle physics, the answer depends upon the masses of the top quark and the Higgs boson. The more massive the Higgs boson, the more likely the universe is to be stable. The more massive the top quark, the more likely the universe is to be metastable, or even unstable. From our current measurements of the top and Higgs masses, it seems that our universe is metastable.

Is the universe a stable quantum system?
Measures of the top quark vs Higgs boson masses, compared to stability calculations. Credit: Sean Carroll

If our understanding is correct, then the universe as a whole could be in a locally , but it could also jump to a lower energy state through a process of quantum tunneling. If that happened, the universe would collapse and we'd all go bye bye. So to our best understanding, it is possible for the universe to collapse. Of course by the same process it is also possible that if you run toward a wall the atoms in your body will quantum tunnel through the wall and you'll find yourself on the other side. The chances of that actually happening is negligible at best.

Of course if the were too stable, that could lead to other problems, such as the idea that we are actually just Boltzmann brains. Being metastable could actually be a good thing rather than a sign of impending doom.

So there's no need to cancel your vacation plans, or stop saving for retirement. Even if there is a cosmic sword of Damocles, the quantum thread holding it is much stronger than you might suspect.

Explore further: Should the Higgs boson have caused our Universe to collapse?

Provided by: One Universe at a Time

0 shares

Related Stories

Could the Higgs mass determine the end of the universe?

February 28, 2013

You may have heard in the recent media that the world was going to end. Uh, again. Worse still, the devastation wasn't limited to Earth; the whole universe might end. Bad news, right? And you thought 2012 was the year to ...

Interview: CERN chief firmer on Higgs boson

January 27, 2013

The world should know with certainty by the middle of this year whether a subatomic particle discovered by scientists is a long-sought Higgs boson, the head of the world's largest atom smasher said Saturday.

Higgs quest deepens into realm of 'New Physics'

July 2, 2014

Two years after making history by unearthing the Higgs boson, the particle that confers mass, physicists are broadening their probe into its identity, hoping this will also solve other great cosmic mysteries.

What is Nothing?

August 22, 2014

Is there any place in the Universe where there's truly nothing? Consider the gaps between stars and galaxies? Or the gaps between atoms? What are the properties of nothing?

Recommended for you

A decade on, smartphone-like software finally heads to space

March 20, 2019

Once a traditional satellite is launched into space, its physical hardware and computer software stay mostly immutable for the rest of its existence as it orbits the Earth, even as the technology it serves on the ground continues ...

Tiny 'water bears' can teach us about survival

March 20, 2019

Earth's ultimate survivors can weather extreme heat, cold, radiation and even the vacuum of space. Now the U.S. military hopes these tiny critters called tardigrades can teach us about true toughness.

Researchers find hidden proteins in bacteria

March 20, 2019

Scientists at the University of Illinois at Chicago have developed a way to identify the beginning of every gene—known as a translation start site or a start codon—in bacterial cell DNA with a single experiment and, through ...

Turn off a light, save a life, says new study

March 20, 2019

We all know that turning off lights and buying energy-efficient appliances affects our financial bottom line. Now, according to a new study by University of Wisconsin-Madison researchers, we know that saving energy also saves ...

31 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

grondilu
5 / 5 (7) Sep 10, 2014
> The stable state of an electron in an atom is its lowest possible energy level, but an electron can be in a higher energy level for a while. Eventually it can drop to a lower energy level, which releases a photon.

They make it sound as if the atom generates energy out of nothing. It doesn't. If an atom can leave the lowest energy state, it's only because it gets energy from its surrounding environment. And it can always do that as long as the temperature of the environment is not zero.

I mean, quantum mechanics is weird, but it's not *that* weird. It does comply to energy conservation.
Jixo
Sep 10, 2014
This comment has been removed by a moderator.
Jixo
Sep 10, 2014
This comment has been removed by a moderator.
Whydening Gyre
5 / 5 (2) Sep 10, 2014
Universe stability DEPENDS on metastable quasi states that allow constant balancing/rebalancing.
Neros Fiddle
1.3 / 5 (4) Sep 10, 2014
Perhaps Black Holes are quantum tunneling.
TomTerrific
1 / 5 (5) Sep 10, 2014
Meow! (let's see how many true nerds are here)
Whydening Gyre
5 / 5 (7) Sep 10, 2014
At least they're calling it a quantum system...

Jixo.
If Hawking changed his opinion 360 degrees, isn't that the same as not changing it at all?

Grondilu.
Thanks for that excellent synopsis.
Aligo
Sep 10, 2014
This comment has been removed by a moderator.
Whydening Gyre
5 / 5 (2) Sep 10, 2014
If Hawking changed his opinion 360 degrees, isn't that the same as not changing it at all?

Yep, you were upvoted for correction. But it's still possible, Hawking lives in 4D space and what we can see it's just a projection of his spin...

Making it half spin off to the left....
telltheworldtheword
4 / 5 (4) Sep 10, 2014
now prove we are not brains in vats, in another dimension.
orti
1.2 / 5 (5) Sep 10, 2014
Everything comes to an end so often. Not to be left out, I predict that a green slime big enough to consume the world, the universe, the multiverse, and maybe even Hawking's ego will do it.
Whydening Gyre
5 / 5 (1) Sep 11, 2014
now prove we are not brains in vats, in another dimension.

Why? This one is much more fun....
kochevnik
4 / 5 (3) Sep 11, 2014
Jixo.
If Hawking changed his opinion 360 degrees, isn't that the same as not changing it at all?
Only the photons and phonons he uses to communicate. His electron potentials would still be precessed as they must spin 720 degrees
Urgelt
5 / 5 (3) Sep 11, 2014
Hawking is smarter than me. But he also has difficulty communicating his ideas when speaking to the public.

He hasn't successfully communicated this one.

He's talking about a phase-change propagating at the speed of light across the entire universe from a single quantum event: a single Higgs bosun changes to a lower energy state via quantum tunneling.

Hawking hasn't explained - in lay terms - why the Higgs can't change energy states locally without triggering a phase change in the entire universe. Other particles do it all the time.

No doubt there's some abstract reasoning behind this notion of a phase change in the entire Higgs field triggered by a single quantum event. But whatever that reasoning is, it's not reaching our ears. That's a communications fail.
Murtagh
3 / 5 (2) Sep 11, 2014
"Making it half spin off to the left..."
...and a step to the ri-i-i-i-ight!!
Blakut
3.7 / 5 (3) Sep 11, 2014
" Higgs bosun" - Raise that mass mateys! YARRR!
DocEigen
5 / 5 (3) Sep 11, 2014
That's it, the nail is in the coffin, we're toast... I'm selling off all my investments and giving the money to... well, to commenters on this list... yes, all of you can now get a chunk of bucks!!

Just show up 1 nanosecond after the universe collapses, and pick up a check.
seanhoran
1 / 5 (4) Sep 11, 2014
I (using very basic models) worked out the odds of tunnelling through the grate wall of china and also bouncing back of a cliff. Neither had a high probability
antialias_physorg
5 / 5 (3) Sep 11, 2014
> The stable state of an electron in an atom is its lowest possible energy level, but an electron can be in a higher energy level for a while. Eventually it can drop to a lower energy level, which releases a photon.

They make it sound as if the atom generates energy out of nothing. It doesn't. If an atom can leave the lowest energy state, it's only because it gets energy from its surrounding environment. And it can always do that as long as the temperature of the environment is not zero.

What they are saying is that we may be currently in the 'excited' state. It's not that the universe would need to make a jump to an higher energy level. It would fall to a lower on.
If I read it correctly then we'd be talking about another symmetry-breaking event. And these events do tend to leave nothing untouched.
Jixo
Sep 11, 2014
This comment has been removed by a moderator.
Jixo
Sep 11, 2014
This comment has been removed by a moderator.
TomTerrific
5 / 5 (3) Sep 11, 2014
Meow! (let's see how many true nerds are here)


Awwww, I guess no one got it. I can sum up the article in five words. We are all Schrodinger's cat.
Jixo
Sep 11, 2014
This comment has been removed by a moderator.
Whydening Gyre
5 / 5 (2) Sep 11, 2014
Meow! (let's see how many true nerds are here)


Awwww, I guess no one got it. I can sum up the article in five words. We are all Schrodinger's cat.

Y'know, Tom - I just thought that was too easy to be the desired response...
zouguyrocks15
1.3 / 5 (3) Sep 11, 2014
Just wondering how you can tell if something is stable or metastable when its moving faster than light? Perhaps 100's of times the speed of light?
Aligo
Sep 12, 2014
This comment has been removed by a moderator.
DDBear
4 / 5 (1) Sep 12, 2014
So even if the universe could collapse in this manner, this would not be any stranger than the concept of the big bang, or the inability to explain qualia of consciousness, and so on. The only aspect that will give credibility (or not) is the physics behind it, not whether it is strange that the universe is on the edge of instability, or the philosophical and insurance problems with it potentially collapsing.
Jixo
Sep 12, 2014
This comment has been removed by a moderator.
nigel_reading
1 / 5 (2) Sep 13, 2014
Metastable states. I can't help but be reminded of self-organised criticality and the thermodynamics of extended, transient entities performing universal Church-Turning computation on the edge of chaos. Perhaps the universe is such a system, an extended-transient dissipative structure, locally lowering it's entropy at all scales by exporting it into a global environment, be it at atomic, planetary or universal scales? That entropy export process and the geometries of those flows are described by the Constructal law of Design in Nature, complimented by the Asynsis principle of how Form follows Flow.
http://asynsis.wordpress.com
http://www.scoop....l-design
http://www.scoop....ctal-law
Neodim
not rated yet Sep 15, 2014
if the universe would be unstable, it would have already collapsed
Aligo
Sep 15, 2014
This comment has been removed by a moderator.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.