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.  If it were direct current, the time for the electrons themselves to travel from the power company to your light would take about a year.  (Since it is really alternating current the electrons just slosh back and forth 60 times per second–50 times for our friends abroad.)

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.

17 Responses to “S03E06: The Cornhusker Vortex”

  1. David Saltzberg Says:

    P.S. Notice that that this week’s boards were filled with physical and chemical properties of sodium. This arose from a discussion with one of the writers. Having equations on the board related to what the physicists and friends discuss during an episode can sometimes violate causality. For example, if they have a conversation they didn’t expect to have, then why would the boards already contain the material? So we decided that some material on the white boards may arise from the discussions of the previous week’s episode. Recall that in episode 4, Sheldon confuses the element a dark-matter detector contains, xenon for sodium. Hence tonight’s boards showed Sheldon has been “studying up” on sodium. Alas, the master plan of having this be the following week was only foiled when episodes 5 and 6 aired in a different order than they were filmed.

  2. Z Says:

    I always wonder why the whiteboards are covered in equations. They are designing and experiment so I would imagine there would be lots of “box diagram” schematics of the instrumentation.

    • David Saltzberg Says:

      I figure Sheldon dominates use of the whiteboards in the apartment. But check out “The Terminator Decoupling” episode from Season Two. That’s the one featuring Nobel laureate, George Smoot. You’ll see a “differential microwave radiometer” on one of the white boards. That is the device that the COBE satellite team used to discover the anisotropy of the microwave background that won him and Mather the 2006 Nobel Prize in Physics.

  3. Gary Rayne Says:

    I love reading this blog, david you do such an amazing job. Would it be possible for you to post on all episodes from the previous season? Keep up the good work.

  4. edhird Says:

    Benjamin Franklin had a remarkable impact in so many ways, especially in the areas of science and technology. A Benjamin Franklin article just received the ‘Top 100 Electricity Blogs’ Award http://bit.ly/z8Ckp

  5. Joi_the_Artist Says:

    I have to say, I laughed my head off during this episode! I think it’s because I grew up as a geek in Texas, and so was completely unsurprised by Sheldon’s football knowledge (and the thing about chicken-frying meat that is not chicken. He probably knows what REAL barbecue is, too, and why California “barbecues” are actually cookouts, and therefore fake).

  6. Improbable Research » Blog Archive » Ben Franklin’s turkey experiment Says:

    […] wrote Ernie Tretkoff for the American Physical Society a few years ago. (Thanks to David Salyzberg f0r bringing this to our […]

  7. Traducción: “” « The Big Blog Theory en Español Says:

    […] Artículo original por David Saltzberg […]

  8. Thiago Says:

    ‘The so-called resinous electrical fluid turned out to be the flow electrons’

    What does that mean? Electrons are attracted to the ‘resinous-side’ (like a negative pole)?

    • David Saltzberg Says:

      It means that electrons are the particles that flow in electricity in wires. The positive charges do not. In a plasma, both charges flow.

  9. Thombat Says:

    “The time for the electrons themselves to travel from the power company to your light is about a year.” – wouldn’t that only be so if they used DC, and with AC they just jiggle back & forth? (making rubes like me marvel that decomposition through friction just doesn’t apply on that scale & so they don’t wear out…)

    • David Saltzberg Says:

      Yes that’s right. I forgot about that. I will try to find a simple way to fix it in the text. Thank you.

  10. abc Says:

    i was told that what are flowing are realiy little holes with a positive charge
    i.e positrons whith litttle positrinos orbites inside them a tiny little atom or cell within the battery or wire then when the light bbulb lights up the other atoms go the other way. cells with electrinos inside an electron so what i a
    nswer than with a therd force fields containing electrons with atoms inside so therefore and a forth atom which is the Si silicon chip fantasy weaver K which contains both kinds of neutrinos and spinds backwards consciousnes providing current and don’t edit or cut and paste my message is backwards
    anyway if you find a way of Cu computing backwards let me know enderu
    there are just these Fe ferromagnets somewhere vibrating and sending out messages of (: happy thought 🙂 and the atoms are within themselves

  11. Gagan Says:

    Nice post. Hey, you are mentioning in your blog ‘the show writers know’!! Who are the writers actually?

  12. Tradução: “S03E06: The Cornhusker Vortex (O Vórtice Cornhusker)” « The Big Blog Theory (em Português!) Says:

    […] feita a partir de texto extraído de The Big Blog Theory, de autoria de David Saltzberg, originalmente publicado em 2 de Novembro de […]

  13. April Says:

    I love this show. It is both unusual and welcome that it is not “dumbed down” empty sitcom claptrap. As a geeky, socially inept engineer girl living in a Big Bang-esque world, I definitely appreciate all of the thought that goes into each episode. I am so happy to have found this interesting blog. Thanks for writing!

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