S03E08: The Adhesive Duck Deficiency

Tonight’s episode of The Big Bang Theory begins with Howard, Raj, and Leonard camping out in anticipation of the Leonid meteor shower.   True to the writers’ comic timing, the Leonid meteor shower is upon us right now.   The number of meteors per minute will peak tonight (at 5:30A.M. California time, check your local listings.)

But the story really started much earlier than tonight’s opening scene in the desert….it begins November 13, 1833.   Late that night,  insomniac Americans were greeted with a sky filled with streaks of light.  This was not just a meteor shower, but a rare event with so many meteors that it is called a “meteor storm”, so named whenever the number of meteors exceeds 1000 per hour.  That night in 1833 the number of meteors exceeded 1000 per minute!

A traveling preacher,  Samuel Rogers, already awake at 3am to prepare for a journey westward, gave an eyewitness account:

Some of those wandering stars seemed as large as the full moon, or nearly so, and in some cases they appeared to dash at a rapid rate across the general course of the main body of meteors, leaving in their track a bluish light, which gathered into a thin cloud not unlike a puff of smoke from a tobacco-pipe. Some of the meteors were so bright that they were visible for some time after day had fairly dawned. Imagine large snowflakes drifting over your head, so near you that you can distinguish them, one from the other, and yet so thick in the air as to almost obscure the sky; then imagine each snowflake to be a meteor, leaving behind it a tail like a little comet; these meteors of all sizes, from that of a drop of water to that of a great star, having the size of the full moon in appearance: and you may then have some faint idea of this wonderful scene.

Similar stories were reported from across the country.  There was no Moon that night, yet the sky was bright enough to read by.

Theories proliferated quickly.   But it was an observation that explained the phenomenon, 33 years later.  In early 1866,  the U.S. Civil War had just ended a few months earlier, allowing the young naval paymaster Horace Tuttle to take up a post at the U.S. Naval Observatory.  There he returned quietly to his lifelong pursuit of comet hunting.  He soon  found a new one that passed directly through the Earth’s orbit, precisely where the Earth would be in mid-November.   (Since this is an American blog, I’ve  conveniently ignored the fact that Ernst Tempel, a European comet-hunter, already found it two weeks earlier.)    Tuttle’s measurements showed that every 33 years,  this comet, Comet 5P/Tempel-Tuttle, leaves its cold home in the asteroid belt beyond Mars, where it spends most of its time.  It speeds up, passes close to the Sun and returns.    But comets are basically dirty snowballs.  When Comet 5p/Tempel-Tuttle approaches the Sun, the heat of the Sun frees material from its icy core, leaving behind a debris field in space.

The debris orbits the Sun in the same path as the comet, in what is called a “meteoroid swarm”.  Raj tells us what happens next,  “The meteors don’t get here. The earth is moving into their path.” Every year, in mid-November, we Earthlings on our “Spaceship Earth” pass right through the debris field left behind by Comet 5p/Tempel-Tuttle.    The meteoroids in the debris are not stationary, they travel in their own orbit, following the comet’s trajectory.   The meeting of Earth and meteoroids is a classic T-bone traffic accident:

The cause of the Leonid meteor shower: (1) Comet 5P/Temple-Tuttle breaks up a little as it approaches the heat of the Sun, (2 & 3) The debris forms a meteoroid swarm, and (4) The Earth passes through the meteoriods forming the Leonid meteor shower. (Figure from Chaisson & McMillon: A Beginner's Guide to the Universe.)

The meteoroids are mostly tiny, like specks of sand.  Only when the enter the Earth’s atmosphere, at speeds around 40 miles per second into the air do they glow and burn up.  The bright light, the “meteor”, is due to the hot air and hot silicon and other metals in the meteoroid itself glowing from the heat.  Note the terms here:  The speck of sand is a “meteoroid”—it does not become a “meteor” until it is hot and glowing in the Earth’s atmosphere.   If a small rock-like object reaches the ground, that is then called a “meteorite”.  And despite what 5-year-olds might tell you, they are definitely not “falling stars”.

It does not take much air to cause the meteor to glow.   When you see the meteors, they are so high that the air there is less than one part in 100,000 as dense as the air we breathe.   We live in the lowest level of the atmosphere, where the densest air and weather is, called the “troposphere”.   Airplanes fly at around 35,000 feet at the top of the troposphere, a bit below the stratosphere.  A very high level of the atmosphere lies around 275,000 feet.  This layer, the “mesosphere” is where the meteors form. Scientists give it another name though:  “The Ignorosphere”.  That  is because it is barely studied.  It is too low to fly satellites in since the friction from the small amount of air would destroy their orbits.  But it is too high for flying scientific balloons, because there is not enough air to provide buoyancy.    A friend of mine studies it the only way to get there, by sending up sounding rockets.  But such rockets spend only about 5-10  minutes in that region before falling down, so we have precious little direct data.   (My friend was not very  happy during Season One when Sheldon took great offense at his sister calling him a rocket scientist.)

The Leonids storm of 1833 played a major role in our understanding that meteorites in space caused meteors.  Some suspected that meteors were an atmospheric phenomenon, and doubted there were  rocks or pebbles in space.  When two Northern farmers claimed that they saw a meteoroid  fall from their sky to their farm, Thomas Jefferson remarked:

I  would rather believe that two Yankee farmers lied than to believe that rocks fall from the sky.

Yet the meteors of the 1833 storm came from a spot on the sky that moved with the stars.   In fact, from the direction of the constellation Leo, hence the name  “Leonids”.   Since their point of origin did not stay fixed in the atmosphere, but rotated with the Earth,  that showed the meteors to be initiated by objects from space.  Don’t feel bad for Thomas Jefferson though, it was just one of many things he had wrong.

Astronomers predict that this year’s Leonids will put on an excellent show tonight.  Try to get out of the city and see them.  Camp overnight if you can.  Just watch out!  There will be science teachers  out there.

S03E07: The Guitarist Amplification

“Hiding in my bedroom blaring a Richard Feynman lecture”, Sheldon tells us is where he could be found when he was hiding from difficult situations as a child.   He may have done this often, since there are over 100  hours of recordings of Feynman’s famous lectures delivered to Caltech freshmen in 1961-3.    The lectures were transcribed and edited into a famous three volume set aptly titled “The Feynman Lectures on Physics.”  Open the book and on the first page of your journey, you will be greeted with a perhaps unexpected  image of an author of a physics textbook:

Richard Feynman: physicist, Nobel laureate, teacher, bongo drummer

Every physics major should own a copy.  I keep a set at my office and home so as not to be at a loss.

Being part of a physics faculty, when I foolishly don’t walk fast enough down the hallway I am sometimes called upon to help decide what textbook we should use in our first-year courses.  Writing a general physics textbook is heroic undertaking and I greatly admire the work of  those authors. Yet, the texts are remarkably (probably necessarily) similar in organization and content.   Even  if you look at a first-year physics textbook from 50 years ago, you will not find it much different than one we use today.  (Except most modern books add distracting colors and take about twice as many pages to get it said.  If you are a physics major, you can do yourself a big favor by finding a used copy of “University Physics” by Sears and Zemansky dating from the 1950’s.)  By contrast,  Feynman’s lectures are unique.  His take on everything is his own.   Even after all these years, his lectures are astounding in their freshness.  His lectures do more than explain the physics (which they do beautifully), but Feynman uses them to teach how to approach physics as a physicist.  He often leads the reader to seeing the essential question about a topic.  They are just inspirational.

While intended for first-year undergraduate students, The Feynman Lectures come into their own for graduate students in physics.  Many physics graduate programs have a big exam for graduate students at the end of their first year.  It is administered over several days and often even has an oral-exam component in front of a panel  of professors.  The students must pass it to stay and enter the university’s Ph.D. program.  For the students spending a summer studying for this exam, The Feynman Lectures are rarely out of arm’s reach.   (Students understandably dread this exam, but when it is all over, they  look back fondly and say it was a wonderful way to spend a summer.)   I went through the same ritual and to this day, whenever I am stuck understanding a concept while teaching a first-year class, I turn to Feynman and invariably find the answer in his lectures.

Unfortunately, a  first approach the Feynman Lectures can be a bit daunting.   A common criticism is that they were even above the heads of their target audience of Caltech physics majors.  Fortunately, physics fans  can still get a excellent sample of Richard Feynman, the lecturer, since Microsoft’s Project Tuva recently made available a copy of Feynman giving “The Messenger Lectures.”

Feynman lectures on gravity (Click image for videos.)

Much has been written of Feynman, especially by himself.   Richard Feynman was a hero of many young students interested in physics growing up.  Not because he won a Nobel Prize–many physicists have done this–but  for his stories of a life in physics.  A classic that I first encountered and devoured while in high school is his hilarious and slightly subversive memoir  Surely You’re Joking, Mr. Feynman! If you were to read just one thing about Feynman, or any scientist for that matter, I recommend that book.  If you hunt around, you will  find many more hours of audio tapes of the master himself recounting these stories in preparation for the book.

It’s a wonder Sheldon ever came out of his bedroom.

S03E06: The Cornhusker Vortex

American readers of this blog can be forgiven for considering Benjamin Franklin (1706-1790) primarily as a statesman.  Admittedly he did some minor things along this line:  helping draft the United States’ Declaration of Independence and serving as the ambassador to France where he secured support for the American War of Independence.  Franklin was even the country’s Postmaster General at a time when the postal service was important, not delivering mostly junk-mail.  But the show’s writers know what Sheldon knows, that Benjamin Franklin was a major physicist.

PHYSICIST Benjamin Franklin on U.S. currency

Franklin’s interest in electricity began with  electrocuting turkeys for his friends’ amusement, but after once shocking himself unconscious he concentrated on more scientific endeavors.  In tonight’s episode, Sheldon enumerated three of Franklin’s inventions:   Using the principles of thermodynamics,  Franklin invented the “Franklin stove”, which transfers more warm air to a room than an ordinary fireplace, while still satisfying the important detail that the poisonous exhaust exit the chimney.   Using the principles of optics, Franklin made “bifocal lenses”, which contain glass with its upper and lower parts ground with different curvatures so that they bend light at steeper or narrower angles.  Such different focusing powers allow the wearer of spectacles to focus on either near or far work without changing glasses–while efficiently allowing us the rest of us to identify people over the age of 43.   Franklin’s “flexible urinary catheter” is an invention best left to the websites that focus on such things specifically.

Electrocuted turkeys notwithstanding, Franklin’s most significant scientific work was in the field of electricity.   In Franklin’s time, two distinct forms of electricity were known and identified as two separate fluids: vitreous and resinous, named after the material it came from.  Vitreous electricity can be produced by rubbing glass with silk (“vitreum” being Latin for “glass”) and resinous electricity charge can be produced by amber resin with fur (“resin” being English for “resin”).   Franklin noticed a conservation law between the two types of fluids whenever they were generated.  He speculated that rather than creating two separate electrical fluids with rubbing, a single electrical fluid was in all material and merely redistributed by rubbing.  He speculated that vitreous electricity was an excess of this single fluid and resinous its deficit.   A one-fluid theory is correct for  nearly all electricity we encounter.  The so-called resinous electrical fluid turned out to be the flow electrons while the so-called vitreous fluid is just the remainder of the atoms left behind.  For example, in the copper wires in your house, the fluid that flows is really electrons.  But there was one “gotcha”.  Franklin had a 50/50 chance to guess which fluid was the excess and which the deficit—and he got it wrong.  Ever since, the sign physicists apply to the charge of an electron is negative.  In a circuit, the flow of the electrons  is exactly opposite what is labeled the electric current.  That tricky minus sign survives to this day,  allowing me and my colleagues to confuse a new set of physics students every year.

The speed of the fluid in copper, that is the speed of the electrons in a copper wire, is a remarkably slow quarter-inch per second.  Yet when you turn on the light switch in a room, the lights appear immediately.  So, how can a light switch work so fast?  The analogy I give my students is turning on the hot water faucet in their shower.  The water immediate flows because the pipes are full of water, but notice the water starts cold.   It still takes up to a minute for the hot water, which has to flow from the  hot water heater, to reach the shower.  The same is true for electrons in your house wiring.  The copper wires are filled with with electrons and the the power company’s generator is pushing on the electrons at its end of the wire.  When the switch is closed (“turned on”), that push on the long line of electrons pushes on the electrons in your lightswitch, and in turn in the wire inside the lightbulb, producing light.   The push is what matters.  The time for the electrons themselves to travel from the power company to your light is about a year.

Ultimately, the two-fluid model turned out not to be wrong.   Modern experiments, such as those of Barry Kripke, Sheldon’s nemesis, produce materials called plasmas.  Plasmas are created when you heat a material so high that the negative electrons break free of the positively charged  atomic nucleus in each atom and even the atomic nuclei break free of each other.   In a plasma, both the negatively charged electrons and the positively charged nuclei in a plasma move freely.  Plasma physics experiments like Kripke’s manipulate both types of electrical fluids.

At the time, Franklin described his reaction to his discoveries as “Chagrin’d a little that we have hitherto been able to discover nothing  in this way of use to mankind”.  Given how important electricity is to modern life, his words remind us that the fruits of fundamental research to humanity are not always immediately apparent.

Wolowitz wraps up their Benjamin Franklin discussion with “To learn more about our founding fathers visit your local public library.”   That was highly appropriate since Franklin founded the first lending library in America, the predecessor to our free public libraries.  Franklin’s electrical work is honored to this day by the naming of the official unit of charge (in the centimeters-grams-seconds system) as the “franklin” (Fr).  To learn more about electricity, visit your local public library.

S03E05:The Creepy Candy Coating Corollary

In Catch-22, Airman Dunbar spends all his free time with people he doesn’t like.  That makes time go by slower so he can enjoy life longer.

Physicists have their own way of slowing time.    Moving clocks tick slower than ones at rest.  Not because something goes wrong with the mechanism of a moving clock, but rather the passage of time itself slows down.  This effect, called “time dilation” is sufficiently familiar that the writers used it in joke by Leonard about a double-date that couldn’t end soon enough:  “Approaching the speed of light doesn’t slow down time. Approaching them does.”

It is tempting to use this as a launching point to discuss how a little-known patent clerk in Switzerland spent all his free time in 1905 thinking about physics problems (there was no internet or video games) and predicted all this.   That was Einstein and this was his special theory of relativity.  Normally, I love teaching special relativity.   I especially love teaching it to freshmen since so little math is required: just  distance equals rate times time and how a right-triangle works.  Yet,  I won’t do it here because it really isn’t because of the theory of relativity that we believe time goes slower for moving objects.  True, the theory of relativity is beautiful and Einstein was a one of the smartest guys ever.  But physics departments’ trash cans are full of beautiful theories and many brilliant people are long forgotten.  The real reason we believe in time dilation  is because experiments say it is so.  It is better to delve into one of them.

Particle accelerators (a.k.a. atom smashers) are great places to find things moving near the speed of light.     In the 1990’s I worked at the world’s largest particle accelerator, an international scientific laboratory called CERN, as a “post-doc”.  (A post-doc is the few years in a physicist’s life just after receiving a doctorate but before taking on a permanent post.  Although it has never been stated in the show, I think Leonard, Sheldon and Raj are all post-docs.)   While I was working at CERN,  my friends and I needed particles to test and align our detector.  The accelerator division kindly  sent us a beam of particles called muons.  Muons are just like electrons but they are heavy and undergo radioactive decay quickly, living on average for only 2.2 millionths of a second (0.0000022 seconds).  Even though these muons moved at nearly the speed of light, even light traverses only 2200 feet in 2.2 millionths of a second.  You might think that when being sent from one side of the (large) lab to the other,  you would lose most of them to decay before they arrived.  Yet,  “time dilation” came to our rescue.  The muons we needed to calibrate our detector moved at 99.9999% the speed of light and we saw their internal clocks slow down by a factor of 1000, meaning they lived 1000 times longer.   It was no problem to bring them a safe, long distance from the accelerator, down to our experiment, where we made good use of them.

CERN. The world’s largest and most powerful particle accelerator. Its longest beampipe crosses between two countries, France and Switzerland

If you could ask them, what would the muons say happened?  They likely would say that they were are at rest the whole time and rather it was me, my friends,and the whole lab moving towards them at 99.9999% the speed of light.  They are not moving so they would still measure their own average life as 2.2 millionths of a second; so how did they get across the lab to our detector without decaying?  If asked, the muons would report the distance across the lab to our experiment was 1000 times shorter than we would.  Moving near light speeds, moving objects become much shorter.  Such “length contraction” is an experimental fact.   While the muons and I may have disagreed why they reached my experiment without decaying, we both agree on the important part:  They did.

Could speed be the secret to Dunbar’s quest for longevity?  Can physicists make fountain of youth by the slowing down time with speed?  Yes…but there’s a catch.  Even if we put you on a fast rocket ship, since time slows down, your metabolic rate slows as well.  Everything around you undergoes the same slower passage of time as witnessed by the rest of us.  So Leonard has it exactly right.   He would experience time unfolding just as if he were at rest.  In fact, Leonard could well say that he really is the one at rest and it is everyone else that is moving.

That’s some catch, that Catch-0.0000022 .

S03E04: The Pirate Solution

In tonight’s episode Raj works alongside Sheldon on “The Dark Matter Problem”.   In my opinion this is the biggest problem in physics today that we have a hope of solving.

Vera Rubin discovers galactic dark matter.

Physicists love it when theories have problems. Like pulling a stray thread on a sweater, it might give you just a tuft of yarn, or it might unravel the whole thing.  The best thing that can happen to a scientist is to ruin somebody’s sweater.

One of the biggest problems of the 19th century was the age of the Earth appeared much larger than the age of the Sun.  Geologists argued (correctly) that the Earth’s age was measured in billions of years based on sedimentation rates.  Meanwhile physicists calculated that for any known energy source, the Sun would have burned out after at most 20 million years.  The physicists’ arguments were convincing and screwed up geology for a century.  Ultimately the problem was resolved by a major change in the way we understand energy.   The advent of nuclear physics in the 1930’s explained that sunshine is powered by nuclear reactions.  By converting mass into energy, a previously unknown energy source, nuclear reactions are nearly a million times more powerful than chemical reactions.  They allow us a 4.5 billion-year old sun.

Maybe that is a bad example to encourage pursuing problems.  Although the Sun-versus-Earth’s age problem signaled a misunderstanding of utmost importance, it was solved only because of work in a completely different subject than astronomy and geology.  This story is typical.

Often physicists just find things out by having a lucky break while toiling away on some other problem.  This happened to physicists in Japan working underground with a big tank of water they called “Kamiokande”.  I remember as a kid reading an essay by Isaac Asimov about their experiment: “After Many a Summer Dies the Proton”, describing their search for a decaying proton.  The theorists said they should find it, since it would solve some of their theoretical problems. Asimov’s title was premature—now, more than twenty-five years later, neither the Japanese nor any other experiment has ever seen a single proton decay.  Meanwhile, the Kamiokande physicists had to study particles called neutrinos crossing their detector since they were a source of noise.  They found while studying this noise an amazing effect called “neutrino oscillations”, which revealed essential properties of neutrinos.  The Japanese physicists had made the biggest scientific discovery in particle physics in decades.  (During that time I was in  Geneva also looking for “neutrino oscillations” with parameters the theorists said were more likely.  We found nothing.)  Had the Kamiokande experiment not been built to chase down this wrong proton-decay prediction by theorists, we wouldn’t have this important discovery.

(Asimov’s essay was just  one of many he wrote about science for the monthly “Fantasy and Science Fiction Magazine”. While I was in junior high school, Asimov’s science article was always the first thing I read when the magazine arrived, not the science fiction stories.  Perhaps that foretold why I am now only a science consultant instead of a writer.)

Our century’s problem, the dark matter problem, has many facets, but the most glaring is the speed of our solar system.  Just as Earth and other planets in our solar system revolve around the Sun, our whole Solar system orbits  the center of the Milky Way galaxy.  While every year the Earth goes around the Sun, every “galactic year” (250,000,000  Earth years, or  nearly 2 billion dog years) the whole solar system makes a full galactic orbit.   Every planet that goes around the Sun does so as described by Newton’s laws of mechanics.  The farther out a planet is from the Sun, the slower it should move, given fairly precisely by the square root of the distance.    For example, Saturn is about 9.5 times farther from Sun than the Earth is from the Sun, and so moves square-root(9.5)=3.1  times as slowly as Earth.    This works because the gravitational pull of the Sun keeps the planets moving in near-circles.   By adding up all the objects that astronomers see, the core of the galaxy should cause the stars in the rest of the galaxy to undergo orbits analogous to the planets’ motion around the Sun.  However, when astrophysicist Vera Rubin made the measurements,  she measured no drop in speed at all. Since astronomers can only count what they can see, what is light, we suspect there is dark matter filling the galaxy that pulls stronger on our solar system and other stars.   So 250,000,000 years may be a long time, but without dark matter it would be much longer.

Speed of stars vs distance from the center of the Milky Way. The Earth and Sun are located at about 8 on the x-axis.

The discovery of dark matter has told us that we don’t even know what 90% of the matter is in the universe.  While we may all be hoping Sheldon gets a Nobel Prize, let’s hope Dr. Rubin is honored as well.

Physicists would love other proof of dark matter, but we don’t even know what it is.  That is what Sheldon and Raj were working on.  Some physicists try to find it in space.  If the dark matter is made of particles that can collide and annihilate, they will give up very energetic light called gamma-rays.  This light is more powerful than even X-rays.  Gamma-ray telescopes around the world are looking for evidence of these dark matter collisions. If you look carefully at the white board, you will see the name of one gamma-ray telescope friends of mine built called “VERITAS”.  You’ll also see a sketch of how it works:  gamma rays hit the upper atmosphere and produce small amounts of light detected by big curved mirrors on the ground.   Meanwhile other physicists are competing to be the first find the dark matter by observing directly the extremely small amount of energy a dark matter particle might deposit in a detector as they pass through Earth.   Some experiments use Sodium (which has an atomic mass 23) and other use Xenon (with atomic mass 131).  Now you know why Raj crosses out 131 and changes it to 23.  Sheldon was calculating the rate for the wrong target material, xenon not sodium.

Tune in next week in two weeks to watch  the apartment’s whiteboards for Sheldon catching up by studying sodium.

S03E03:The Gothowitz Deviation

In tonight’s episode of The Big Bang Theory, the writers dared to go where most physicists will not,  to the philosophical underpinnings of quantum mechanics.  When Penny asks Sheldon to dance with her, he replies:

To tackle a description of the Many Worlds Theory of quantum mechanics (more often called an “Interpretation” rather than “Theory”), we first need to delve into quantum mechanics itself.

Before physicists realized that quantum mechanics was necessary, their view of the world held that the outcome of any event could be completely determined–as long as you had precise enough measurements beforehand.    If you dropped a rose petal into a hurricane, all you needed was the positions and velocities of every molecule of air at just one moment and then you could calculate the final location of the rose petal with certainty.   (OK, you would also need to know all about all the birds and pieces of vinyl siding flying around too.)  As a practical matter, you could never really do this, but at least in principle it would have been possible.

This view changed forever with the discovery of quantum mechanics in the 1920’s and its experimental tests over the following decades.  The outcome of  many situations can never be predicted with certainty.  Take for example carbon-11, a radioactive atom used in life-saving medical imagers called PET scanners.   That carbon atom’s “half-life” is 2 minutes, meaning that half the carbon-11 atoms you possess at any one time will decay and disappear in 2 minutes.  But what if you had only one atom of carbon-11?  No physicist can ever say when it will decay with certainty.  The best we can do is say  that it has a 50% chance of still being around 2 minutes from now; a 25% chance 4 minutes from now; and 1 in a billion chance of being around an hour from now.   To know the exact fate of any one atom  is not a matter of not being able to see well enough inside the atom.  There is no way of ever knowing.

This fundamentally probabilistic description of nature bothered some physicists.   Even Albert Einstein objected famously:  “I am convinced that He [God] does not play dice”.   Convinced as he may have been, and as brilliant as he may have been, experiment trumps genius.    Clever experiments have shown that there is no room for what Einstein was sure of:  hidden deterministic variables that underlie the probabilistic laws of quantum mechanics.

Philosophical questions arise when you put the atom in a box for say 2 minutes and let no one check on it.  Meanwhile the condition of the atom during that time can still affect other measurements, so descriptions of the atom during this time turn out to be both important and open to interpretation.   The founders of quantum mechanics, working largely in Copenhagen, believed that the best way to view the situation was that the atom was simultaneously in a decayed and un-decayed state.   They said that only after some observer comes along and looks in the box would the atom be forced into one state or another.   In the Copenhagen Interpretation, the act of observation changes the universe.  Such is the typical training that physicists such as myself received as undergraduates.

The Copenhagen Interpretation raises difficult, perhaps unanswerable questions:  How large does something have to be to constitute an observer?  If the atom bounces into  another atom that detects its presence, is that other atom an observer?  Is a large, complicated detector a valid observer?  Must the observer possess consciousness?  Must it be human consciousness or can it be a cat’s?  Does another observer that does not know the outcome possess a different “reality”?  The most likely answer to such question is “Shut up and calculate!”.

Thus things stood for decades.  An alternative, the so-called “Many Worlds Interpretation”, emerged from the 1957 Ph.D. thesis of Hugh Everett at Princeton.  Everett never labeled his interpretation “Many Worlds” but rather originally titled his paper   “Wave Mechanics without Probability” ( “wave mechanics” meant “quantum mechanics”)  He later changed the title to something more abstruse to placate his Ph.D. committee.

In Everett’s interpretation, the probabilities were only a consequence, not an elemental part of the theory.   Not only is the state of the atom described by the equations of quantum mechanics, so are all the detectors and observers in the world.   When an object and observer meet, the two affect each other according to the usual rules of quantum mechanics.  No new process happens at the moment of observation.    Of course when an experimentalist observes the atom he or she perceives it as decayed or not; but the experimenter is now part of the system including the atom, experiencing only an “inside” view.  Meanwhile someone else, with an “outside” view, still entertains all outcomes.  The interpretation does not rest on dice.

The persistence of both outcomes in Everett’s interpretation is often described as two different worlds that propagate forward and independently in time:   one where the atom decayed and one where it did not.   Had the life of a cat  hinged on outcome of the decay,  it is often said that our world branches into two worlds, one with a live cat and one with a dead cat.  (Here we are adopting  Schrodinger’s cat, described in the season-one finale, S01E16.  These are hypothetical experiments only—no cats were harmed.)  The critical question of why we experience the world as 100% live or dead cats, never as a mixture,  was left by Everett as an exercise for the reader.

Soon after completing his Ph.D. thesis, Everett ventured to Copenhagen to explain his ideas to Niels  Bohr.  He failed miserably.  Everett left academia, never to return. The world took little notice of his work.

But times have changed.  At a recent meeting of quantum physicists, the Many Worlds Interpretation received more votes than the old Copenhagen interpretation as the picture closest to the participants’ own views.  Still, physics is not a popularity contest.   These were personal opinions, much like Einstein’s unsubstantiated claim about dice.   For the debate to be meaningful there needs to exist some prediction for which the two differ.   Hope exists in some quarters to find such tests, but I can find no specific experiment put forward.   It remains that no matter how opposed the views of two physicists on the topic, they will all calculate exactly the same outcomes of experiments.  Without an experimental prediction that differs, the fight is just a war of words not physics.  A distinction without a difference.

Except for one.  Science fiction writers and physicists alike have entertained one intrepid experiment.   The means of distinction rely on an experimenter having no fear of  approaching quantum suicide–by playing a game of quantum  Russian Roulette.  The observer  shoots a gun at his or her own head with a 50% chance of having a bullet vs. a blank.  After many trials the physicist will know if Many-Worlds is favored, since there is no experiencing a world where you are dead.  Many Worlds predicts that the observer will eventually live in a world having survived the game 100 times or more.  Unfortunately, we can never can never know what result our brave physicist friend found.  There is no way for the survivor(s), if any, to tell us.

I’ve done some stupid things for physics…

but I won’t be volunteering for the quantum suicide experiment.  It violates my university’s ethics protocols for experiments involving human subjects.

In the Many Worlds Interpretation, some measurements can encompass an infinite number of final states, or as Sheldon characterizes it:  an infinite number Sheldons in an infinite number of universes.   Luckily for us, the number of Sheldons is not just an ordinary infinity, but an even larger one called  uncountably infinite number of Sheldons.

(Full disclosure: I am a novice to this subtle and deep discussion that physicists have been having for decades. The full story is far more complex than described here.  At best, I’ve given the reader a sense of the issues, while–I hope–saying nothing that is actually wrong.   I very much welcome an email or comment on any incorrect matters of fact.)

S03E02: The Jiminy Conjecture

I fear that this episode may have disappointed over 10 million people—because there was no physics in it.   It has biology: crickets chirping, entomology, and even a discussion of the neurobiology of alcohol’s effect on the brain.  But apparently no physics.

Not so fast.   Physicists work on biological problems all the time.   So much so that at my own university, UCLA, there is a popular undergraduate major in biophysics.   The fundamental equation of the episode,  the rate of chirps of a cricket versus temperature, as Sheldon tells us, was given by A. E. Dolbear in 1890.  Dr. Dolbear was a professor of physics at Tufts College, not biology.   If you look carefully, you will see his equations describing temperature (in Fahrenheit) versus the number of cricket chirps per minute on the whiteboard in the boys’ apartment.

Dolbear's Law: Equation describing how a cricket's chirps per minute (N) is related to the ambient temperature (T).

Of course it must be given separately for the common field cricket (FC) as well as the Snowy Tree Cricket (STC)  and even Katydid (K).  Each chirp is made when the cricket rubs its right forewing against its left forewing that is covered with ridges.  In the process, the creation of this sound is much like running your fingernail over the teeth of a comb.  For insects, the behavior is called stridulation.  For a person strumming a comb, it is probably just called annoying.

The alert viewer no doubt noticed that one digit was different on the whiteboard in the episode than above.  Also, Prof. Dolbear’s first name was Amos, not Emile.  So much for the fact checking by the show’s consultant.

Modern biophysics looks different from Dolbear’s time.  Physicists work on fundamental biological problems, such how a cell works using the special points of view and tools they they have been trained with.   For example,  proteins drive much of the activity of a cell and the subtle folding and unfolding of proteins that occur versus temperature are key to the cellular activity.  Using statistical mechanics, non-linear dynamics, and laboratory techniques borrowed from the physical sciences, physicists are characterizing this key aspect of proteins and thereby understanding the inner workings of a cell.   In another example, a friend of mine tries to understand how our inner ear manages to be such a good amplifier, allowing us to hear both extremely quiet and loud sounds entirely with a small hair that moves only one billionth of a meter and produces very little extraneous noise.

Several years earlier Dolbear had previously done very important work as a physicst.  In 1885 he performed the first wireless telegraphy—several years before Guglielmo Marconi.

New York Times article, Oct 6 1899

So Dolbear was the first to perform wireless telegraphy.  Without wireless telegraphy we’d have no radio.  Without radio we’d have neither the technology for television, nor the first sit-coms written for radio.  And without either, we’d have no show The Big Bang Theory.

S03E01: The Electric Can Opener Fluctuation

Sheldon, Leonard, Raj and Howard have finally returned from their National Science Foundation expedition above the Arctic Circle, having  been away from the apartment (and us) for the past three months.  Even the whiteboards in their apartment have not changed–they are as they were left in the season finale.  Sheldon is ecstatic about their trip, convinced the data he’s collected will win him a Nobel Prize.   Sheldon has finally observed a signal of magnetic monopoles.

Or has he?  Sheldon is a theorist, not an experimentalist.  We saw Sheldon’s experimental skills on display back in the fighting robots episode–he could not even open the toolbox.   An experimentalist is always on the lookout for stray signals, or “noise”.  Every discovery is not initially met with shouting and champagne as one might expect, but close consideration of every recorded signal as a mundane process that could possibly be noise fooling the apparatus.  The process can take years.

A few years ago, I was taking data with some electronics we set up with scientists from the Jet Propulsion Lab in the pedestal of their large (230-foot diameter) radio telescope.   We designed the electronics to look for neutrinos, but by design the apparatus  would record a signal, most likely an uninteresting background, about once every six minutes.   But there was something else going on.  Sometimes we would see a burst of signals recorded at once.   Could it be that neutrinos were arriving in bursts?   Ultimately it turned out to occur whenever someone sat in a particular chair. When its wheels passed over a speck of dirt on the floor,  the weight would compress it slightly and cause a tiny spark, much like how a piezoelectric cigarette lighter works.  That was a source of electrical noise.   With a quick tweak to the electronics, we were on our way with no more chair-trigger  events.

Coming back to Sheldon’s experiment, some time ago an experiment at Stanford saw a beautiful magnetic monopole candidate.  The induced current in a loop of superconducting wire took a sudden jump, as measured by the magnetic flux through the loop.  The event became famous:

Other experiments sometimes noticed that such jumps could be produced by ordinary electrical noise:  interference, perhaps from spark plugs, or,  as Sheldon eventually finds out,  from a nearby small motor.    An electric motor constantly makes and breaks electrical contact with small brushes that carry the current from a spinning wheel.  These interruptions  in the circuit can make a very tiny spark, and thus produce a spurious electrical signal, noise.   You can sometimes hear these on your AM radio as static.   Still, the Stanford event was special because the change in current was exactly the value expected from a magnetic monopole.  The experimenters were absolutely first-rate and took pains to show they were not subject to stray electrical noise.   A monopole was never seen again.  But the world’s one candidate has never been disproved either.

S02E23: The Monopolar Expedition

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:

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:

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

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:

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.

Welcome to The Big Blog Theory

The science of The Big Bang Theory is revealed!  (Of the sit-com that is, not the theory of the origin of the universe.)  Last season, I was discussing possible titles for this blog with the writers of the show, who had lots of  terrific ideas.  After all, that’s what writers do.   One of the lead actors passed by, overheard us,  and  gave us this title over his shoulder,  just as he was walking into a scene.

The title “The Big Bang Theory”  was originally a name of derision.   (Of the theory of the origin of universe that is, not the sit-com.)  Starting in the 1940’s, Fred Hoyle and other proponents of a theory they called the “Steady State Theory” of the  universe,  took the observation that  the universe  expanding as discovered by Edwin Hubble in the 1920’s, and proposed that the universe was constantly generating new matter to fill the new space.  They went further to say the new matter was generated at exactly the rate to keep the universe always looking the same at all times.

The Steady-Staters dubbed this idea  “the perfect cosmological principle”.  “Perfect” because their universe was the same at all times, compared to the more prosaic “cosmological principle”,  whose universe is merely the same in all places (homogeneity) and in all directions (isotropy).    Some readers may complain that such a cosmological principle is clearly not true.  Of course standing on Mars your immediate neighborhood would look quite different than to someone standing (briefly) in the central core of Jupiter.  However, the cosmological principle applies only to the universe only on its largest scales, distances crossing many hundreds  of galaxies.  The principle is an empirical observation,  something subject to change if observations ever dictate it.  There are even some tantalizing hints in recent data to that effect.

A view of the Universe on the largest scales ever observed. Every dot is a galaxy. Although features like walls and voids are visible, on the largest scales (hundreds of millions of light years) the universe appears homogenous and isotropic.

Their rival theory originated a couple of decades earlier, in the 1920’s.  A Belgian priest, Georges Lemaître, took  guidance from the (then) recent theory of General Relativity by Einstein and  proposed that all the matter and energy in the universe was created in a single event and the universe became less dense as it expanded.    Perhaps Lemaître, a priest,  was pleased with the creation event implicit in the model.  The Steady-Staters disagreed with the  idea that so much matter and energy could be created in a single event and Hoyle poked fun at Lemaître’s theory by giving it the moniker “The Big Bang” during a radio interview in 1949.

The Steady-State and Big-Bang models each were plausible and provided a good description of the history and evolution of the universe.   But at least one had to be wrong.  Fortunately, like all useful theories,  each made definite and distinct predictions which could be tested by observation.   It took several decades, but by now, the Steady-State idea is in conflict with a wide variety of data.  For example, the two theories predict a different number of distant galaxies, and the numbers found by astronomers agree with the Big Bang Theory and disagree with the Steady State Theory.    Moreover, the relative abundance of  elements such as deuterium, helium and lithium compared to hydrogen can be measured.  The data are explained well by the entire universe having been a nuclear reactor when it was between about 3 and 20 minutes old, a state which the Big Bang Theory implies the universe must have gone through, but never existed in the Steady State model.   The final death knell of the Steady State theory occurred in the 1960’s when a microwave radiation was observed coming from all directions in the sky.  This radiation, now known to be the oldest light in the universe is called the “Cosmic Microwave Background”.  It was produced when the early universe was hot and opaque, a period that never existed in the Steady State model and which it could not explain.

A more advanced summary of problems with the Steady State idea is given by my friend Ned Wright in his terrific cosmology tutorial.

The Steady-Staters were not crack-pots, and they were certainly not dumb. Quite the contrary, Fred Hoyle was the first to describe how heavy elements were synthesized from hydrogen and helium in stars.   Many of the observations which eventually favored the Big Bang Theory took a long time to become convincing.  For example, it took decades to unravel what fraction of lithium observed was primordial and what was generated later in cores of stars.   The initially predicted age of the universe by the Big Bang Theory made it younger than the oldest stars, a situation only fixed when the difficult to measure expansion rate was finally pinned down.

Even after most of the scientific community favored the Big Bang Theory,  Hoyle tried to keep the Steady State theory alive.  While some have ridiculed his stance, there is a healthy place in scientific discorse for a few serious-minded skeptics.  Hoyle continued to mold the Steady-State Theory to explain the data although the theory necessarily became more and more baroque.    Ever the skeptic, later in life Hoyle challenged that biological evolution could be driven by natural selection.   However, one of his basic ideas, panspermia, that the building blocks of life may have come to Earth on comets was for a time  a serious contender.   At least two views of such contrariness can be taken:  Perhaps his skepticism caused a sharpening of the mainstream arguments, overall serving science by making its arguments stronger.   Or perhaps we are left to take comfort in the adage:   Funeral by funeral science marches on.

Perhaps most importantly, had the Steady State Theory been right, the theme song to the show would have been nowhere near as interesting:

The whole universe was in a Steady State.

And nearly 14 billion years ago, nothing special happened, wait…

…