Posts Tagged ‘S02E23’

S02E23: The Monopolar Expedition

September 20, 2009

In this epsiode, the season-two finale, Sheldon wins a National Science Foundation grant to go to the Arctic and look for a magnetic monopole.   He’s excited because if he finds them, he would finally win his Nobel Prize.

What is a magnetic monopole?  “Mono” is Greek for “alone”, but every magnet ever made or found always has at least two poles, called North and South.   As a child I would play with magnets that had two poles and looked like this:

dipole-b

The North pole of a magnet is always attracted to another’s South Pole and like poles (North-North and South-South) always repel.

If anyone ever discovers a magnetic monopole, a Nobel prize is assured.  So it’s worth a try.  What if you tried to be clever and make a monopole by cutting the magnet above in half?  You can try this at home with a hacksaw and a friend’s magnet:

two-dipoles-b

Too bad. You’ve just made two smaller magnets each with their own North and South poles.   Try again. The same thing keeps happening:

four-dipoles-b

Ad infinitem (or more precisely, whatever Latin is for “to the smallest”).   At some point you will cut the magnet so small that you will have cut down to the size of a single  atom.  (Atom being Greek for “do not cut”.)   Even then, a single atom often behaves as a magnet, but always with both a North and South pole, and you can’t cut it any finer.  Well, with a lot of money, you can cut even the atom into to subatomic particles:  protons, neutrons and electrons, but even these little magnets still always have one  North and South magnetic pole.   With a pile more money, you can cut the proton and neutrons into their smallest parts, quarks, you will still have magnets with North and South poles.  Nobody knows if it is possible to cut an electron or quark but particle physicists keep trying.

Magnetic monopoles have been tantalizing physicists for over a century.  In the late 19th century, the Scottish theorist James Clerk Maxwell summarized everything that was known about electricity and magnetism with just four simple equations.  (They weren’t so simple the way he wrote them, but we’ve cleaned them up since then.)   These equations displayed a beautiful symmetry of form between electricity and magnetism.    In fact one point where they lacked symmetry between electricity and magnetism  led Maxwell to add a term and as a result he (correctly) predicted how light is comprised of just oscillating electric and magnetic fields.  This was one of the most amazing moments in all of physics.

But there is one glaring obvious lack of symmetry remaining in Maxwell’s equations.  Electric monopoles are everywhere you look: Electrons are a monopole of one charge and protons are a monopole with the other charge.    Yet not a single magnetic monopole is ever found.  We are forced to put a zero in Maxwell’s equations that breaks their otherwise  symmetrical treatment of electricity and magnetism.  Now, over one hundred years later, modern theories such as string theory predict the existence of magnetic monopoles.  However, since there is little that string theory does not predict, the question remains to be proven by experiment, perhaps Sheldon’s experiment….

Scientists have looked for magnetic monopoles, in particular in the 1980’s when they were predicted by a Grand Unified Theory which was beautiful, theoretically compelling, and wrong.  Sheldon’s idea was to take his motivations from string theory and improve on the old experimental technique by using the Earth’s magnetic field to increase his chances.   Much like you can collect more rain and more accurately measure the rainfall by putting a funnel over a cylinder,  Sheldon’s idea was to use the Earth’s magnetic field as a funnel for magnetic monopoles.  Oddly enough, the Earth’s  “North” magnetic pole is the “South” pole of the Earth’s magnet, and vice-versa.  That means “North” magnetic poles would be directed to the Arctic, and South magnetic poles would be directed to the Antarctic.    (There is a loophole that the monopoles can’t be moving to fast.  Listen carefully to the dialogue and you’ll hear Sheldon say “slow-moving magnetic monopoles”.)  The show’s writers knew that the Antarctic is inaccessible in May (the time the season finale aired) so sent Sheldon and his friends to the Arctic.

The National Science Foundation’s polar programs helps scientists, including me, move themselves and their gear into the polar regions to conduct their science.  They give us the gear, training, and support so we don’t kill ourselves out in the field.  For this episode, the NSF gave the show their official logo to use, which you can see on all the boys’ shipping crates.  The boys’  clothing are exactly the same ones that are issued to the scientists in the real polar program:  Their red parkas are extremely warm and nick-named “Big Red” by polar scientists.  Even their big white (sometimes blue)  insulated boots, which scientists call “bunny boots” are issued to real scientists by the NSF.  Here’s a picture of our science team wearing the gear on the ice:

group-on-ice

Physicists on ice.

A fun fact to impress your friends when watching this episode in re-runs:  The diagrams on the whiteboard in Sheldon and Leonard’s apartment show classic equations and diagrams describing magnetic monopoles.


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