Another Way the LHC Could Self-Destruct 367
KentuckyFC writes "Just when you thought it was safe to switch on the LHC (though it won't be for a while yet), another nightmare scenario has emerged that some critics worry could cause the particle accelerator to explode. The culprit this time is not an Earth-swallowing black hole but a 'Bose supernova' in the accelerator's superfluid helium bath. Physicists have been playing with Bose Einstein Condensate (BECs) for over 10 years now. But in 2001, one group discovered that placing them in a powerful magnetic field could cause the attractive forces between atoms to become repulsive. That caused their BEC to explode in a Bose supernova — which they called a 'Bosenova,' a name that fortunately did not catch on. This was little more than a curiosity when only a microscopic blob of cold matter was involved. But superfluid liquid helium is also BEC. And physicists have suddenly remembered that the LHC is swimming in 700,000 liters of the stuff while being zapped by some of the most powerful magnetic fields on the planet. So is the LHC a Bose supernova waiting to go off? Not according to the CERN theory division, which has published its calculations that show the LHC is safe (abstract). They also point out that no other superfluid helium handling facility has mysteriously blown itself to pieces."
bad physics, bad press (Score:5, Informative)
An expanding BEC isn't anywhere close to a supernova. This would be similar to snapping the valve off of a liquid helium tank. The guys at CERN could blow themselves up with this, but that's about it. They could blow themselves up lots of ways.
It was called a "bosenova" because it shrinks before it expands, not because it's super destructive.
Worser (Score:5, Informative)
Could it be worse than melting a 40-ton magnet, which actually happened?
Re:First Law? (Score:5, Informative)
Re:Phase change (Score:5, Informative)
also, lolwtfsig
Cassandra's predictions were right (Score:5, Informative)
That's the point of the myth: Apollo granted her the gift of prophesy, then cursed her by making it so nobody would ever believe her predictions.
Re:More Cassandra warnings... (Score:5, Informative)
Uh huh. And the various (admittedly foolish) motorcycle drivers I see riding on their bikes at 80mph without helmets are just holding their breath?
Re:First Law? (Score:5, Informative)
In addition, magnets have been run at that temperature before.
Re:More Cassandra warnings... (Score:3, Informative)
Re:LHC Joke of the Day! (Score:2, Informative)
If he's cleaning the inside of it, then he's not a janitor, he's a vacuum cleaner.
- RG>
Re:Phase change (Score:4, Informative)
Re:More Cassandra warnings... (Score:2, Informative)
That isn't a very good example either. Hurricanes typically gust up to 100+ MPH. Sustained winds are often less than that, 60% or so of the maximum gust speed. But more importantly, nobody really rides out a hurricane unshielded, and if anything, you can turn 180 degrees away from the winds if you need to breathe inside a storm. It's a little difficult to turn 180 degrees in a car, not to mention dangerous. I guarantee you'll have trouble breathing behind the wheel of a car without a windshield at 30MPH.
Regardless, the car analogy is inappropriate. The physical effects of high levels of stress on the human body have been well studied for many centuries now. It hasn't necessarily been well understood, and there haven't been latin-based names for every little phenomena, but the effects have been known.
With the LHC, we're entering uncharted territory, and not in the sense of parting the next clump of bushes to see what's behind. It is uncharted territory in the sense that we're charging through the next clump of bushes to see what's on the other side when we're legally blind and have left our glasses at home. It's probably more trees on the other side, but there's always a chance of a cliff. And while it's not that easy to fall even if there was a cliff, it's possible to slip on some wet foilage or trip on a low branch or root.
Re:I was worried, but am ok now (Score:5, Informative)
I don't know how this FUD even came up. It's such a ridiculous idea to begin with.
No Bosenovas in liquid helium (Score:2, Informative)
Magnetic fields of precisely tuned strengths (not particularly strong fields) can make certain atoms in an ultra-cold, ultra-low-pressure gas attract each other. It is only at much lower temperatures than that of liquid helium, in the more-than-icy stillness of nanokelvin gases, that the gentle collapse and rebound caused by sudden atomic attraction could ever be considered an explosion. 'Bosenova' was an apt name, but only by remote analogy.
The attraction effect does not work on helium, because there are no He-2 molecular states to provide a Feshbach resonance. And it does not work on liquids, because in a liquid the ordinary interactions between atoms are so much stronger anyway than anything this Feshbach effect would induce. It has nothing to do with superfluidity per se; it's a phenomenon of cold, dilute gases, which happen also to become superfluid in some cases. So no LHC liquid helium is going to go Bosenova.
Superconducting magnets themselves are quite dangerous if not handled properly. They can indeed explode: look up 'superconducting magnet quench'. The risk scale here is that of wrecking LHC equipment, however, not of turning the big ring into a crater. And it has nothing to do with Bosenovas.
Bull (Score:3, Informative)
Also, people have been constantly working on this stuff since then, with even larger currents (hence larger magnetic fields) and I think it's pretty safe to assume that the LHC is gonna be fine (at least this part of the machine).
Bose Nova at Wikipedia (Score:2, Informative)
A bosenova or bose supernova is a very small, supernova-like explosion, which can be induced in a Boseâ"Einstein condensate (BEC) by changing the magnetic field in which the BEC is located, so that the BEC quantum wavefunction's self-interaction becomes attractive.
In the particular experiment when a bosenova was first detected, this procedure caused the BEC to implode and shrink beyond detection, and then suddenly explode. In this explosion, about half of the atoms in the condensate seem to have disappeared from the experiment altogether, remaining undetected either in the cold particle remnants or in the expanding gas cloud produced.
That's actually pretty interesting. So, it won't happen unless the magnetic field is changed in such a way that the quantum wavefunction becomes self-attractive (whatever that means.) So, don't do that and we're all set? Though, the part about it making atoms disappear is pretty cool. I wonder what actually happens to them...
Re:Phase change (Score:2, Informative)
Helium Bose Nova are Impossible. (Score:3, Informative)
It's impopssible for superfluid helium to 'go nova'. This impossibility is well understood by theory - It's not that there's a miniscule-but-nonzero chance, as there is that the LHC could spontaneously produce tiny dragons - In this case it's *impossible*.
Here's the explanation:
http://anticrackpot.blogspot.com/2008/09/there-will-be-no-bose-novae-at-lhc.html
And a personal request: Take a second to look some of this stuff up before you post an article like this that fuels unfounded (indeed, indefensible) fears.