Strange matter, as scientists call it, is unarguably weird. It's unlike any matter on Earth. For one, it's heavier than our matter, but that's just the beginning. Our beloved matter is organized. It's made of atoms, which contain nuclei packed with protons and neutrons. Indeed, our quarks, which are basic particles, stay neatly packaged inside the protons and neutrons. But in strange matter, there are no boundaries; it's just a lump in which the quarks run amok, roaming top to bottom and end to end.
Did we mention that strange matter isn't known to exist anywhere in the universe? That's an important detail. Physicists came up with the idea of strange matter in the 1970s when they wondered what would happen if protons and neutrons were squished superhumanly hard [source: Freedman].
Let's repeat a similar version of their theoretical experiment, imagining we have an iron atom, plus a piston able to squish it with enormous force. By compressing the nucleus of the iron atom, we add energy to its 26 protons and 30 neutrons. If we press hard enough, the protons and neutrons will burst apart into what they're made of: smaller particles called quarks. We'll then have a mess of quarks -- the type of quarks called "up" and "down," which have certain masses and are the only kinds found in matter on Earth. Squishing even more, we'll stress the up and down quarks so much that some change their identities. Some will get a lot heavier and become strange quarks. Our familiar iron atom will be long gone. We will have squished it into an equal mix of up, down and strange quarks -- in other words, into a strangelet. A strangelet is a small piece of strange matter.
Physicists found it too irresistible not to keep playing with strange matter. They wondered what would happen if they released the pressure on the newly made hypothetical strangelet. Would it immediately transform back into the orderly iron atom? Edward Witten of the Institute for Advanced Study suggested maybe the strangelet would stay around. In fact, maybe it would be more stable than the iron atom or any matter on Earth.
On the next page, our story will turn from strange to scary.
Can Strange Matter Attack Me in the Street?
Could strange matter be on Earth now? Physicists have considered it. They've sampled our water and other matter, finding nothing. They've considered the possibility of creating strange matter in particle accelerators like the Large Hadron Collider, since it could slam atomic nuclei together hard enough to knock the quarks out of the atoms and potentially convert some of them to strange quarks. But safety reviewers concluded that particle accelerators create so much heat that they would melt potential strangelets. The likelihood of creating strange matter in a particle accelerator would be as low as making "an ice cube in a furnace," the reviewers concluded [source: Ellis].
Physicists have also considered whether strange matter could exist in space. They've nixed the idea that it could've been made in the early universe and stayed around [source: Farhi]. They're skeptical of it being made by heavy atoms, which are hurled through space by violent astrophysical processes, hitting other heavy atoms in the process [source: Jaffe].
Edward Farhi, an MIT physicist who researched strangelets, thinks the most likely place to find strange matter is in neutron stars. These collapsing stars compress their interiors forcefully. "At the core, you have densities and pressures large enough to form strange matter. If strange matter formed in the core, it would eat its way out and consume the star," says Farhi. Underneath its crust, the star would become a lump of strange matter, or a strange star. If two strange stars collided, they could send strange matter careening toward Earth, says Farhi.
How could strange matter be dangerous? Under special circumstances, it "eats" other matter. In order for this to happen, the strange matter has to be more stable than the matter it meets and not repel it. If those conditions are met, the other matter will "want" to convert to strange matter, and contact between the two will get things going. The result would be an ever-growing ball of strange matter, burning through matter like a fireball.
For such a disaster scenario to occur on Earth, strange matter would have to remain for more than a fraction of a second at earthly pressures, and we don't know if it can do that. It would also have to be negatively charged.
In fact, potential strange matter would probably be positively charged, says Farhi. And since the matter on our planet (including us) has positively charged atomic nuclei, it would repel strange matter. "If you had a little lump on the table, it would just sit there," says Farhi.
The scenario would change if strange matter were negatively charged, and a ball of it was madly rolling around on Earth. "You would probably know it because it would be growing and consuming everything at its border," says Farhi. Attracted to your atomic nuclei, the ball of strange matter would suck you in, and you'd be finished. Kind of like a modern-day incarnation of the Blob.
Have you counted the "ifs" we've thrown at you so far? If strange matter existed in space, if it were hurled at Earth, if it were stable at the pressures in space and on Earth, if it were more stable than our matter and if it were negatively charged -- it could turn you into a lump of unruly quarks. So no, you probably shouldn't be afraid of strange matter, but it's fun to think about.
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More Great Links
- Ellis, John et al. "Review of the Safety of LHC Collisions." 2008. (12/11/2008). http://lsag.web.cern.ch/lsag/LSAG-Report.pdf.
- Farhi, Edward. Personal interview. Conducted 12/11/2008.
- Freedman, Barry and Larry McLerran. "Quark Star Phenomenology." Physical Review D. Vol. 17, No. 4. Feb. 15, 1978.
- Jaffe, Robert et al. "Review of Speculative "Disaster Scenarios" at RHIC." Review of Modern Physics. Vol. 72, No. 4. October 2000.