Pop quiz: States of matter

[unixronin]

OK, folks, let's test your scientific knowledge.

[Poll #1278483]

Most grade school science classes still teach that there are three states of matter — solid, liquid, and gas.  But there are several others.

• If you heat and compress any substance beyond its thermodynamic critical point, the result is a supercritical fluid that behaves in many respects like a liquid and like a gas simultaneously.  If you drink decaf coffee, it's likely it was decaffeinated using supercritical carbon dioxide.
• If you pump sufficient energy into any substance possessing atomic structure, its electrons become dissociated from the atomic nuclei, forming a plasma, a highly energetic cloud of free electrons and nuclei.  Plasmas behave like gases in most respects, but have several useful additional properties.  Fluorescent lights (including CFLs) and neon tubes employ plasmas, as do the various experimental fusion reactors that rely on magnetic confinement.
• Compress any normal atomic matter enough, and its atomic structure collapses.  This gets us into a whole class of states of matter known collectively as degenerate matter.  The most common form of degenerate matter is probably the electron-degerate matter believed to compose white dwarf stars, while the best known is what used to be called neutronium, now more correctly termed neutron-degenerate matter.  Weirder, possibly speculative members of the family include strange matter, quark matter (aka QCD matter), and possibly preon matter.
• As several people have reminded me, if you cool a substance sufficiently, slowing its atomic motion until the atoms are essentially at rest, their position becomes uncertain due to Heisenberg's uncertainty principle, and the wave functions of the atoms spread out accordingly. If you can cool therm enough that their wave functions overlap, you get a Bose-Einstein condensate — a cloud of atoms all in exactly the same quantum state, acting as though they were one giant atom.  (However, the atoms you start with have to be bosons.)

So if you answered "Six or more", you're correct.  Probably.  As far as we know.  For now.  And remember, this isn't an exhaustive list.

Comments

[hugh-mannity.livejournal.com]

Hmmmm... It's obviously far too long since I was in high school.

[glitch25.livejournal.com]

Good stuff. I always remembered the traditional 3 plus plasma. but yeah.. this day and age, there is all kinds of interesting stuff.

[gdmusumeci.livejournal.com]

Superconductors are also considered to be a separate state in some theoretical regimes. Also, quark-gluon plasmas (aka QCD) was very likely been experimentally generated at CERN in 2000....

Matter! It's what's for dinner!

[unixronin.livejournal.com]

I think considering superconductors to be a separate state of matter is rather stretching the definition, especially since superconductivity is a property that seems to appear in several widely different classes of materials under several different sets of conditions (and since we're not even entirely certain yet that the same basic mechanism underlies it in all cases).

[cipherpunk.livejournal.com]

Actually, superconductors aren't just considered to be a separate state — they're definitively known to be a separate state. (Or, at least, the current flowing down them is known to be.)

In most conventional superconductors, superconductivity forms as the result of electrons forming Cooper pairs as they travel along the circuit. Cooper pairing is the electron analogue to superfluidity and/or Bose-Einstein condensates, all of which are really just different facets of a different phase of matter.

[unixronin.livejournal.com]

That was sort of my point. The superconducting current flow is an altered phenomenon able to occur in an unaltered material below a critical temperature, but crossing that critical temperature doesn't (as far as we yet understand) create any actual changes in the material itself.

We need to understand a lot more about superconductivity than we do. Discovering Cooper pairs was only part of the puzzle.

[dr-nebula.livejournal.com]

And of course - there's the mysterious 'dark matter' that composes over 95% of the universe.

When I was a teacher - I taught the standard 4 states (s/l/g +plasma) in 9th grade and covered degenerate matter states in 12th grade physics.

[unixronin.livejournal.com]

And of course - there's the mysterious 'dark matter' that composes over 95% of the universe.

Though so far, nobody seems to be able to quite agree either on exactly what it is, or how much of it there is — and for that matter, at present even our arguments for its existence at all are based entirely on inferential evidence. We have observations that don't fit classical theories, so we infer that something else is there, but we don't really know what it is.

[cipherpunk.livejournal.com]

The dark matter skeptics, such as myself, find unusual parallels between dark matter and luminiferous ether. In the case of the ether, we concluded it existed, that it must exist, because the alternative was that our understanding of physics was totally bogus.

Then along came Einstein, who showed us that Newtonian physics was totally bogus.

It's still quite possible the same will happen with dark matter. I'm not persuaded by arguments from necessity. The universe is not required to refrain from upending our theories. :)

[unixronin.livejournal.com]

Neither am I.

First, there was dark matter. Then, the CDM theorists had to invent dark energy because they couldn't explain everything with dark matter. And then there's the Bullet Nebula, which was at first trumpeted as proof of dark matter, but then the CDM theorists realized they actually couldn't explain it even using both dark matter and dark energy, so at least one CDM group decided it was necessary to invent a fifth basic force whose properties are completely undefined except that it makes the calculations on the Bullet Nebula work (i.e, match the observations).


"Would you like epicycles with that?"

[smandal.livejournal.com]

I'd like to see the paper for that makes this claim.

AFAIK, the cold dark matter model is completely consistent with the Bullet Cluster; dark energy ("Lambda" in "Lambda-CDM") is not relevant here, as its effect is negligible on such a small scale.

WMAP observations of the cosmic microwave background are concordant with the dark matter fraction given by lensing, mass-to-light measurements and rotation curves, as well as the dark energy fraction inferred by the acceleration of supernovae.

MOND is ruled out because it is not consistent with tests of general relativity, which come up null. TeVeS is still alive, but only (IMHO) tendentiously. Much of the motivation is gone since the Bullet Cluster observation, as the whole point was to make baryons create the same gravitational effects that are conventionally explained by CDM and Lambda. Well, lensing by the Bullet Cluster shows there is a lot more mass that behaves just like CDM with the baryons trailing far behind in the shockwave from the collision.

[ithildae.livejournal.com]

The ironic thing is that epicycles actually work. If you think of them as coefficients of a Fourier series with circles as the orthogonal basis vectors, it all works. The only real problem is that you need an infinite sequence of coefficients. (How many digits do you really need for calculations? In Tycho's day they used about fourteen.)

[rosencrantz23.livejournal.com]

huh. I knew the traditional solid/liquid/gas -- plasma states, but hadn't run across the other states you mentioned. Thanks for the info!

/colours self enlightened

[lwj2.livejournal.com]

Same here.

[argonel.livejournal.com]

I'm reasonably familiar with the standard 4 and as a metallurgisy I'm also familier with those parts of phase diagrams where the distinctions are basically dotted lines. As such I'm not sure that supercritical fluids should count as another state of matter. I should read up on them sometime and see what the more detailed arguments boil down to. Degenerate matter is another one of those cases that are fuzzy enough that I'm not sure it should count as a state of matter or as an exception. Based on the physics and and second or third hand observations we can be pretty confident that they exist, but without an atomic structure should they really count as matter? After some thought I'll provisianally classify them as matter since they have both mass and volume, but they definately don't fit into nice neat little niches.

[cipherpunk.livejournal.com]

Gravitational singularities are degenerate matter consisting of mass but no volume. I'm not sure if this is an argument for or against degenerate matter being counted as a distinct phase, but I figured the data point of "not all degenerate matter has volume" should be thrown out.

[skellington.livejournal.com]

Bose-Einstein Condensate is another new one they've discovered recently. (I did the classic 3, plus plasma and BEC for my vote of 5.)

The wikipedia entry lists 11 possible states, depending on what you consider.

Personally, as a purely definitional question, any state that most atoms can't enter, or that consists of particles other than atoms, doesn't qualify as "matter" to me.

[unixronin.livejournal.com]

So what, then, would you say that neutronium (or neutron-degenerate matter) is, if not matter? It's not composed of atoms, and complete atoms cannot enter that state without becoming no longer composed of atoms. The same also applies to an electron cloud or a quark-gluon fluid.

Are you proposing a third basic category alongside, but separate from, matter and energy?

[skellington.livejournal.com]

I'd normally consider an electron cloud or stream of electrons, a form or state of energy because when it interacts with "normal" matter, it will do so as electrical energy. As a practical matter, as a computer geek, that's probably a reasonable abstraction for the world I inhabit.

The wikipedia article on "matter" points out that this is a layman's term, and generally physicists will refer to "mass, energy, and particles".

http://en.wikipedia.org/wiki/Matter

(They also point out that some objects that have mass aren't necessarily matter, such as W and Z bosons, so that isn't a useful distinction.)

States of baryonic matter (i.e. protons and neutrons) would probably be closest to my definition of the question, which excludes degenerate matter and electron clouds (and quark-gluon fluids). But it would include plasmas, BEC, and the other various exotic states.

[robbat2.livejournal.com]

I wouldn't really consider BEC to be that "new". I actually remember a radio news announcement about it, in 1995, while still living in South Africa (age 13). At the time, I was just getting in the car in St Augustine's hospital, after having gone for a checkup.

[skellington.livejournal.com]

Basic science trivia that has changed since I graduated college counts as "new" in my world. I need a grumpy old man icon. :-)

[dafydd.livejournal.com]

*snerk* I overthought. "Normal" matter, degenerate matter, and plasmas... :p

[otherbill.livejournal.com]

I said six. I could only come up with five, but figure there's at least one we haven't discovered yet.

(On a completely unrelated note, would you mind weighing in here (http://otherbill.livejournal.com/360284.html)?)

[unixronin.livejournal.com]

I saw that, but couldn't really come up with a better suggestion than VNC, which you'd already mentioned. It works well, it's fast, and it's free.

[otherbill.livejournal.com]

How much should I worry about security here? gundo said to wrap it in ssh, but I don't know how to do that.

If it's sitting behind a reasonably-secured wireless router, will the free version be sufficient, or should I shell out the $30 for the Personal Edition (w/ security/encryption)?

[unixronin.livejournal.com]

Well, that's not necessarily a simple thing to do. Basically it means you have to create an ssh tunnel either to the box in question, or to some other machine in between that can gateway for you. This means the remote end of your tunnel needs to have an sshd, which for most purposes means it has to be some flavor of *nix box.

The basic concept is like this: You tell ssh on your box that it is to establish a persistent SSH connection to a specified port on the remote machine, listen for connections to port X, and forward them over that SSH connection. Meanwhile, the remote machine has been told that packets coming in over that SSH connection are to be forwarded to the VNC port on the target machine. (And vice versa in the other direction.) You open a VNC connection to the designated port on your own machine, and through the magic of ssh tunnelling, the other end of the connection gets attached to the target machine.


As for the second question, that's really unanswerable without knowing how secure you need it to be. My first reaction, though, is that wireless connections are slow to start with. VNC over an encrypted wireless connection is likely to be agonizing. It'll be usable in an emergency, but I wouldn't want to do work over it on a regular basis.

[smandal.livejournal.com]

I answered six or more. Yay, they won't kick me out of grad school!

[databeast.livejournal.com]

fuckit. I forgot superfluids, and I didnt even think that strange matter really counted (since, AFAIK, we've never seen any of it)

[unixronin.livejournal.com]

Strange matter is definitely in the speculative category.

[metahacker.livejournal.com]

I counted solid, liquid, gas, plasma; BEC; superfluids. Missed degenerate matter, though if I gave it time, perhaps.

I don't think strange or quark matter can exist, but perhaps it's just a matter of the right conditions. (This is due to my understanding of what quarks are, or rather, what they aren't -- separable entities. But then I'm sure that's what 19th C physicists said about neutronium.)

[micheinnz.livejournal.com]

You're also forgetting Bose-Einstein Condensate.

[ithildae.livejournal.com]

I pick three. It is certain that we can produce more, but the ones we interact with in our environment are, solid, liquid, gas. I will give you plasma. Hitting a triple point is interesting. (Try putting dry ice in a soda bottle. You will end up with solid, liquid and gas CO2 in the same container. Open the bottle very carefully!)

There are things like BEC, that become very interesting. It is clear that we do not understand matter at the level we need to in order to interact with the universe constructively. There is just too much that we are finding that we don't know. If we look at the potential possibilities, six just seems far too limiting.