Bubbles, dimensions, and black holes

One of the weirder claims of modern physics, which I first ran into when I was reading about string theory a few years ago, is that the universe could have more than three spatial dimensions -- but the extra ones are "curled up" and are (extremely) sub-microscopic.

I've heard it explained by an analogy of an ant walking on a string.  There are two ways the ant can go -- back and forth on the string, or around the string.  The "around the string" dimension is curled into a loop, whereas the back-and-forth one has a much greater spatial extent.

Scale that up, if your brain can handle it, to three dimensions of the back-and-forth variety, and as many as nine or ten of the around-the-string variety, and you've got an idea of what the claim is.

The problem is, those extra dimensions have proven to be pretty thoroughly undetectable, which has led critics to quote Wolfgang Pauli's quip, that it's a theory that "is not even wrong," it's unverifiable -- which is synonymous to saying "it isn't science."  But the theorists are still trying like mad to find an indirect method to show the existence of these extra dimensions.

To no avail at the present, although we did have an interesting piece added to the puzzle a while back that I somehow missed the first time 'round.  Astronomers Katie Mack of North Carolina State University and Robert McNees of Loyola University published a paper in arXiv that puts a strict limit on the number of macroscopic dimensions -- and that limit is three.

So sorry, fans of A Wrinkle in Time, there's no such thing as the tesseract.  The number of dimensions is three, and three is the number of dimensions.  Not four.  Nor two, unless thou proceedest on to three. 

Five is right out.

The argument by Mack and McNees -- which, although I have a B.S. in physics, I can't begin to comprehend fully -- boils down to the fact that the universe is still here.  If there were extra macroscopic spatial dimensions (whether or not we were aware of them) it would be possible that two cosmic particles of sufficient energy could collide and generate a miniature black hole, which would then give rise to a universe with different physical laws.  This new universe would expand like a bubble rising in a lake, its boundaries moving at the speed of light, ripping apart everything down to and including atoms as it went.

"If you’re standing nearby when the bubble starts to expand, you don’t see it coming," Mack said.  "If it’s coming at you from below, your feet stop existing before your mind realizes that."

This has been one of the concerns about the Large Hadron Collider, since the LHC's entire purpose is to slam together particles at enormous velocities.  Ruth Gregory of Durham University showed eight years ago that there was a non-zero possibility of generating a black hole that way, which triggered the usual suspects to conjecture that the scientists were trying to destroy the universe.  Why they would do that, when they inhabit said universe, is beyond me.  In fact, since they'd be standing right next to the Collider when it happened, they'd go first, before they even had a chance to cackle maniacally and rub their hands together about the fate of the rest of us.

"The black holes are quite naughty," Gregory said, which is a sentence that is impossible to hear in anything but a British accent.  "They really want to seed vacuum decay.  It’s a very strong process, if it can proceed."

"No structures can exist," Mack added.  "We’d just blink out of existence."

Of course, it hasn't happened, so that's good news.  Although I suppose this wouldn't be a bad way to go, all things considered.  At least it would be over quickly, not to mention being spectacular.  "Here lies Gordon, killed during the formation of a new universe," my epitaph could read, although there wouldn't be anyone around to write it, nor anything to write it on.

Which is kind of disappointing.

Anyhow, what Mack and McNees have shown is that this scenario could only happen if there was a fourth macroscopic dimension, and since it hasn't happened in the universe's 13.8 billion year history, it probably isn't going to.

So don't cancel your meetings this week.  Mack and McNees have shown that any additional spatial dimensions over the usual three must be smaller than 1.6 nanometers, which is about three times the diameter of your average atom; bigger than that, and we would already have become victims of "vacuum decay," as the expanding-bubble idea is called.

A cheering notion, that.  Although I have to say, it's an indication of how bad everything else has gotten that "We're not dead yet" is the best I can do for good news.

That's our news from the world of scientific research -- particle collisions, expanding black holes, and vacuum decay.  Myself, I'm not going to worry about it.  I figure if it happens, I'll be gone so fast I won't have time to be upset at my imminent demise, and afterwards none of my loved ones will be around to care.  Another happy thought is that I'll take Nick Fuentes, Tucker Carlson, Elon Musk, Stephen Miller, and Andrew Tate along with me, which might almost make destroying the entire universe worth it.

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False vacuum catastrophe

It's odd how enamored people are of things that could destroy the entire universe.

I mean, on one level I get it.  The sheer power of the natural world is pretty awe-inspiring, and as I've mentioned before, if I hadn't become a mild-mannered novelist, I definitely would have been a a tornado chaser.  That same love of extreme danger (especially when it's not you experiencing it) explains shows like The Deadliest Catch and the innumerable quasi-documentaries wherein divers swim around in chum-filled waters and still act surprised when they're attacked by sharks.

But on a larger scale, there's a real curiosity about things that could wipe out pretty much everything.  A while back, I wrote a piece about people sounding gleeful that we might be looking down the gun barrel of a gamma-ray burster (we're not), and over and over we've heard alarmists suggesting that CERN was going to create a black hole that would eat the Earth (it's not).  But that doesn't begin to exhaust the ways in which we all could die in horrible agony.

Which brings us to the concept of the false vacuum.

Sounds harmless enough, doesn't it?  Well, this is in the long tradition of physicists giving seriously weird things cutesy names, like "strange quarks" and "glueballs."

The idea of the false vacuum is that the universe is currently in a "metastable state."  What this means is that right now we're in a locally stable configuration, but if something destabilizes us a little bit, we might find ourselves suddenly plunging into a more stable state -- a "true vacuum."  The situation, then, would be similar to that of the little ball in the graph below:

As long as nothing disturbs the status quo, the ball is stable; but if something gives it a push up the hill in the middle, it'll crest the hill and find itself rushing downward into a more stable position -- the "true vacuum."

Why this concerns anyone but the physicists is that the result of our reconfiguring into a true vacuum would be that a bubble would form, rushing outward at the speed of light, and destroying everything in its path.

The Standard Model of Particle Physics suggests that from the mass of the Higgs boson and the top quark, an estimate could be made of just how likely this is.  Writer Robert Walker concludes, from the research of Joseph Lykken and others, that the answer is "not very:"

[I]f it could happen, then you’d expect it to have happened already in the first 1/10,000,000,000th of a second along with the other symmetry breaking when gravity split off from the other forces, when it was tremendously hot...

 
Since that hasn’t happened, the false vacuum has to be very stable, or else, probably as we find new physics we find out that it is not in a false vacuum state at all.

 
And yes, on the basis of the measured mass of the Higgs boson, the false vacuum has to be very stable.  Joseph Lykken says that an event that triggers a patch of true vacuum, if the theory is correct, happens on average once every ten thousand trillion, trillion, trillion, trillion, trillion, trillion, trillion, trillion years.

 
That means it is nothing to be worried about.

Walker, who is a mathematician, says that the likelihood of a true vacuum bubble occurring in any given century is less than the likelihood of purchasing tickets for twelve consecutive Euromillions lotteries, and winning the jackpot for all of them.

So "don't worry about it" seems to be an understatement.

However, that hasn't stopped the alarmists from freaking out about it, probably largely due to the fact that if it did happen, it would be pretty catastrophic.  Also, because a lot of them seem to feel that the physicists (for this, read "mad scientists") are actively trying to trigger the creation of a true vacuum, which would be an idiotic thing to do even if it were possible because they'd be the first ones to get vaporized, and wouldn't even have the pleasure of standing around rubbing their hands together and cackling maniacally for more than about a nanosecond.

But then there are the ones who think that it could happen accidentally (again, because of CERN, of course), and the physicists are simply being reckless, not suicidal.  I tend to agree with Walker, though.  I'm way more worried about the idiotic things humans are currently doing to the environment, and our determination to slaughter each other over things like who has the best Invisible Friend, than I am about triggering the Scary Bubble of Death.

Anyhow.  That's our Terrifying Thing That Can Kill you for today, along with some soothing words about why it's not very likely.  Now ya'll'll have to excuse me, because I'm gonna go have a pint of beer and watch Twister for the seventeenth time.

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Condensation and inflation

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I still recall my astonishment when one of my physics professors in college said, "We understand the physics of the universe fairly well back to about one-trillionth of a second after the Big Bang.  Before that, though, things are a little dicey."

To me, that sounded like having a pretty good handle on things, but that first one-trillionth of a second was pretty spectacular.  There were some extraordinary things going on very early along in that tiny time span -- from about 10⁻³⁶ to sometime between 10⁻³³ and 10⁻³² seconds after the initial singularity.  For those of you who are not mathematical types, this is the time between:

0.000000000000000000000000000000000001 seconds, and

0.0000000000000000000000000000001 seconds following the Big Bang.

This era is called the "inflationary period," a term that was coined by Alan Guth (then at Cornell) and Andrei Linde of Stanford, way back in 1979, who were investigating the question of why there are no magnetic monopoles (magnetic particles with only a north or south pole, but not both) and stumbled upon a phenomenon called a false vacuum that accounted for the known properties of matter and the universe.  The problem was, the mathematics of the false vacuum required a period extremely early on in the universe's history when it underwent exponential expansion.  If you thought the time duration of inflation defied the imagination, the size expansion is worse -- in that minuscule fraction of a second, the universe increased in volume by a factor of 10⁷⁸ -- one followed by 78 zeroes.

(Regular readers of Skeptophilia may remember that a while back, I wrote about a rather hysterical article that was making the rounds, speculating about the likelihood of our false vacuum state being superseded by a true vacuum -- which would rapidly destroy the entire universe.  The general conclusion of the physicists is that the risk of this is close enough to zero that you shouldn't be losing any sleep over it.)

[Image licensed under the Creative Commons Original: Drbogdan Vector: Yinweichen, History of the Universe, CC BY-SA 3.0]

As crazy as this sounds, it's been borne up by the evidence.  The vast majority of the research done on this topic is far beyond me even considering my B.S. in physics, but suffice it to say that most physicists accept inflation as a reality.  It accounts for a number of interesting phenomena, including isotropy -- that the universe looks homogeneous no matter what direction you look, which begs an explanation unless you think that the Earth is located in the dead center of the universe, a possibility that is even less than our risk of being destroyed by a true vacuum.  So it may sound hard to believe, but apparently, this enormous expansion in an unimaginably tiny fraction of a second actually happened.

Just last week there was another piece of evidence added to all of this, wherein scientists at the University of Maryland created a peculiar form of matter called a Bose-Einstein condensate that exhibited the properties of cosmic inflation, albeit (and fortunately) on a much smaller scale.  Emily Conover, over at Science News, describes the experiment as follows:

Shaped into a tiny, rapidly expanding ring, the condensate grew from about 23 micrometers in diameter to about four times that size in just 15 milliseconds.  The behavior of that widening condensate re-created some of the physics of inflation, a brief period just after the Big Bang during which the universe rapidly ballooned in size (SN Online: 12/11/13) before settling into a more moderate expansion rate. 

In physics, seemingly unrelated systems can have similarities under the hood. Scientists have previously used Bose-Einstein condensates to simulate other mysteries of the cosmos, such as black holes (SN: 11/15/14, p. 14).  And the comparison between Bose-Einstein condensates and inflation is particularly apt: A hypothetical substance called the inflaton field is thought to drive the universe’s extreme expansion, and particles associated with that field, known as inflatons, all take on the same quantum state, just as atoms do in the condensate.

Another point in favor of this research having recreated on some level the early expansion of the universe is that sound waves sent through the condensate increased in wavelength -- just as light has been red-shifted by the expansion of the space it's traveling through.

I'd be lying if I said I understood last week's paper on anything but the most rudimentary level, but it still gives me a sense of wonder that we can peer into the distant past -- into a time that lasted almost no time at all -- and use that information to draw conclusions about why the universe has the properties it does.   The progress we've made in expanding scientific understanding, in just the last twenty years, is mind-boggling.

All of which makes me wonder what the next twenty years will bring.  I'm hoping it's a warp drive, but that might be a forlorn hope, given that the General Theory of Relativity is strictly enforced in most jurisdictions.

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False vacuum catastrophe

It's odd how enamored people are of things that could destroy the entire universe.

I mean, on one level I get it.  The sheer power of the natural world is pretty awe-inspiring, and as I've mentioned before, if I hadn't become a mild-mannered high school biology teacher, I definitely would have been a a tornado chaser.  That same love of extreme danger (especially when it's not you experiencing it) explains shows like The Deadliest Catch and the innumerable quasi-documentaries wherein divers swim around in chum-filled waters and still seem surprised when they're attacked by sharks.

But on a larger scale, there's a real curiosity about things that could wipe out pretty much everything.  A while back, I wrote a piece about people sounding gleeful that we might be looking down the gun barrel of a gamma-ray burster (we're not), and over and over we've heard alarmists suggesting that CERN was going to create a black hole that would eat the Earth (it's not).  But that doesn't begin to exhaust the ways in which we all could die in horrible agony.

Which brings us to the concept of the false vacuum.

Sounds harmless enough, doesn't it?  Well, this is in the long tradition of physicists giving seriously weird things cutesy names, like "strange quarks" and "glueballs."

The idea of the false vacuum is that the universe is currently in a "metastable state."  What this means is that right now we're in a locally stable configuration, but if something destabilizes us a little bit, we might find ourselves suddenly plunging into a more stable state -- a "true vacuum."  The situation, then would be similar to that of the little ball in the graph below:

As long as nothing disturbs the status quo, the ball is stable; but if something gives it a push up the hill in the middle, it'll crest the hill and find itself rushing downward into a more stable position -- the "true vacuum."

Why this concerns anyone but the physicists is that the result of our reconfiguring into a true vacuum would be that a bubble would form, rushing outward at the speed of light, and destroying everything in its path.

The Standard Model of Particle Physics suggests that from the mass of the Higgs boson and the top quark, an estimate could be made of just how likely this is.  Writer Robert Walker concludes, from the research of Joseph Lykken and others, that the answer is "not very:"

[I]f it could happen, then you’d expect it to have happened already in the first 1/10,000,000,000th of a second along with the other symmetry breaking when gravity split off from the other forces, when it was tremendously hot... 

Since that hasn’t happened, the false vacuum has to be very stable, or else, probably as we find new physics we find out that it is not in a false vacuum state at all. 

And yes, on the basis of the measured mass of the Higgs boson, the false vacuum has to be very stable.  Joseph Lykken says that an event that triggers a patch of true vacuum, if the theory is correct, happens on average once every 10, 000, trillion, trillion, trillion, trillion, trillion, trillion, trillion, trillion years. 

That means it is nothing to be worried about.

Walker, who is a mathematician, says that the likelihood of a true vacuum bubble occurring in any given century is less than the likelihood of purchasing tickets for twelve consecutive Euromillions lotteries, and winning the jackpot for all of them.

So "don't worry about it" seems to be an understatement.

However, that hasn't stopped the alarmists from freaking out about it, probably largely due to the fact that if it did happen, it would be pretty catastrophic.  Also, because a lot of them seem to feel that the physicists (for this, read "mad scientists") are actively trying to trigger the creation of a true vacuum, which would be an idiotic thing to do even if it were possible because they'd be the first ones to get vaporized, and wouldn't even have the pleasure of standing around rubbing their hands together and cackling maniacally for more than about a microsecond.

But then there are the ones who think that it could happen accidentally (again, because of CERN, of course), and the physicists are simply being reckless, not suicidal.  I tend to agree with Walker, though.  I'm way more worried about the idiotic things humans are currently doing to the environment, and our determination to slaughter each other over things like who has the best Invisible Friend, than I am about triggering the Scary Bubble of Death.

Anyhow.  That's our Terrifying Thing That Can Kill you for today, along with some soothing words about why it's not very likely.  Now you'll have to excuse me, because I'm gonna go have a pint of beer and watch Twister for the 17th time.