Some Matter is Strange, but that’s okay

“People fear death even more than pain. It’s strange that they fear death. Life hurts a lot more than death. At the point of death, the pain is over. Yeah, I guess it is a friend.” –Jim Morrison


Yes, Jim Morrison, some people are quite strange, too.

People Are Strange
But that’s not what I’m talking about. You see, one of the “doomsday” scenarios people are talking about over at the Large Hadron Collider (LHC) — in addition to black holes — are out-of-control strangelets.

Let’s talk about what these things are, what people are afraid of, and whether there really is anything worth fearing.

Over at the LHC, they take ultra-high-energy protons and collide them into other ultra-high-energy protons, moving almost (but not quite) at the speed of light. These collisions, when they take place, produce a huge shower of particles — some stable, some unstable — and that’s why we have the giant detectors that we do!

After all, we are trying to make some new, undiscovered-as-of-yet states of matter, such as the Higgs Boson. We’ve already discovered all of the quarks (up, down, strange, charm, bottom, and top), but we haven’t discovered all of the possible combinations of them. Yet.

Here’s something you might not know, though. The LHC, by smashing protons into protons, won’t be able to make some of these states!

For some of them, you need many, many more protons than simply one-at-a-time. So we can smash heavy ions together, such as gold or lead nuclei, instead of protons! One accelerator, RHIC, has already been studying this.

And this is great for physics! Not only are we studying high energies, we’re also studying high densities at the same time; conditions that aren’t around anywhere except at the centers of extreme stars and when the Universe is less than one second old!

Normal matter — protons and neutrons — are made up only of up and down quarks. These are the lightest and most stable quarks, but particle accelerators allow us to replace one, two or even all three of these with a strange quark. And when we do this, we get a new, short-lived (a fraction of a microsecond) particle!

But instead of just making a single one (or simply a few) of these particles, if we do something like collide gold into gold, we have around four hundred of these nucleons in one place, and they can form — instead of Lithium, Beryllium, Boron, Carbon, etc. — strange versions of them!

In other words, nuclei with a strange quark replacing one of the up or down quarks! Well, one of the new states of matter they hope to create at the LHC, by colliding heavy nuclei at these ultra-high speeds, is a miasma of up, down, and strange quarks, known as a strangelet.

And just like carbon-12 is more stable than three helium-4s, and just like a helium-4 is more stable than a single proton, there’s hope that these bound, heavy, strange-quark-carrying particles will live longer than a single, highly unstable one.

This would be neat; we could create them, study them, and perhaps discover a new state of matter that might have been present when the Universe was just a microsecond old, or that might be present today at the core of collapsed stars, like neutron stars!

But that doesn’t stop people convinced that the LHC will destroy the world from crying out that maybe “death by strangelet” is what’s going to be in our future.

How do they state it could happen?

That if heavier, strange elements are more stable than light ones, it could grow out of control, eating more and more matter until the entire Earth becomes one giant strangelet.

And what I offer to you, in opposition to this point of view, is a little education about how nuclear physics actually works. Yes, heavier elements are more stable; that’s why you can fuse lighter elements into heavier ones (like our Sun does) and still release energy.

But you can also split very heavy elements into lighter ones, releasing energy, and that’s what nuclear fission is!

In other words, you can only get up to a certain point before you get less stable! For things made up of up and down quarks only, the most stable element is Iron, element 26, with 30 neutrons and 26 protons. Anything with more neutrons or protons in there is less stable!

And guess what? Strange quarks — or nuclei with strange quarks in them — are always less stable than ones with only up or down quarks! In other words, things with strange quarks in them will always decay, in a tiny fraction of a second, into something with just up and down quarks.

We see this all the time, and it’s the same for charm and bottom quarks too, as this sample decay shows.

So you can either be afraid of strangelets eating the world and destroying it, or you can learn how nuclear physics actually works, and realize that a super-heavy mass of up, down, and strange quarks will be unstable, and decay into things — like normal elements — that are stable.

This is great stuff to study, and to discover, and to learn how it works. But to fear it? Save that for my Halloween costume, coming to you this weekend! (Here’s last year’s, for those who can’t wait.) Happy Halloween!