S03E21: The Plimpton Situation

In the music world, the death of a star is  precipitated by sex, drugs and rock-n-roll.  In the Universe, the death of a star is precipitated by extinguishing the nuclear fusion reactions in its stellar furnace.  The end result is often one of the most fascinating objects in the universe,  a pulsating neutron star,  “pulsar” for short.

Shortly after discovering pulsars (while still a graduate student in 1967) Jocelyn Bell was told "Miss Bell, you have made the greatest astronomical discovery of the twentieth century".

Neutron stars hold the key to what Dr. Elizabeth Plimpton had written on her hand in this episode.

Dr. Plimpton has the coordinates to what?

The life of a star is a constant tug-of-war.  The force of gravity never ceases pulling all the star’s material inward, attempting to make it smaller and denser.  But a denser star would accelerate the nuclear fusion reactions, raising the star’s temperature.  Like heating a pan of jiffy-pop, the heat causes an outward pressure, trying to making the star larger.   For much of a star’s life the forces strike a balance and stars such as our own stay pretty much the same size for billions of years.

But gravity always wins.  Fo now,our own Sun shines largely by turning hydrogen into helium.  By making a more tightly bound nucleus in this reaction, energy is left over and produces the light and heat of the Sun.   About 5 billion years from now, after its hydrogen is used up, our Sun will turn to alternative energy, fusing  helium into carbon and oxygen, becoming much larger and growing briefly into a Red Giant star (while engulfing Mercury and Venus, and incinerating the Earth) in the process.   But that’s all folks.   Our  Sun will finally run out of energy, and puff off all the excess material.  The Sun’s now naked core will quietly cool.   Gravity will pull it tighter and tighter until the electrons in the Sun resist being pushed any closer together.  The remaining ember of carbon and oxygen is incredibly dense.  A white dwarf  with the mass of the Sun will be the size of only the Earth.  It really isn’t even much of  star any more since it is no longer producing its own energy.  It only glows by  radiating the energy from its former life, a cosmic Zsa Zsa Gabor.

But a star more massive than our Sun face a different fate.    A larger star does not go quietly but often blows off material in a dramatic supernova explosion followed by a gravitational collapse of the remaining core.  The inward pressure due to gravity is so great that the electrons that hold up a White Dwarf are “pushed into” the remaining protons to form neutrons.   The stellar material now moves even further inward under the force of gravity to make an object as dense as an atomic nucleus.  Since it is mostly made of neutrons, it is called a neutron star.   A neutron star 3 times the mass of Sun is so small and dense, it is smaller than Los Angeles.

A typical neutron star is smaller than Los Angeles and more massive than the Sun.

It is so dense, that one teaspoonful of neutron star material here on Earth would weigh as much as a mountain.   As Dr. Plimpton says in the episode, if you went even close to its surface you’d be crushed by its strong gravity.   That is if not first ripped limb-from-limb first by the differences in its strong force of gravity on different sides of your body.

But a neutron star’s useful life is far from over.  While a graduate student Jocelyn Bell and her thesis advisor Anthony Hewish discovered regular bursts, from seconds to fractions of a second, of radio static from specific points in the galaxy.  These turned out to be the fast spinning remnant neutron stars.  Just as when a slowly rotating Olympic skater pulls his or her arms inward to speed up, the small neutron star remnant of a star that probably rotated about once per few weeks, now  rotates every few seconds or even faster.   When the poles of the neutron star point at us on Earth we see a burst of radio and other light.   Just as the spinning lamp in a lighthouse produces a flash of light to those at sea, we on Earth see a bursts of energy from the pulsar as it rotates.  For this and her career’s work, Dr. Bell-Burnell was awarded the highest rank an British citizen can attain, Dame of the Britsh Empire.

And just as the spinning lamps in a lighthouse  produce a regular flash of light for ships, cosmic voyagers would see these pulsars, spinning neutron stars,  as regular and bright beacons from afar.   The Pioneer spacecrafts launched in the 1970s are now leaving the solar system.  With them they take our calling card on a gold-plated plaque.    To instruct whoever or whatever discovers them how to find us, we show them the Earth relative to pulsars, cosmic beacons that will be visible throughout our portion of the Milky Way.

The plaques carried on the Pioneer spacecrafts out of our solar system shows our location relative to 14 neutron stars (pulsars)

I’m told Carl Sagan caught hell for putting naked pictures in space.  So for the subsequent Voyager spacecrafts, now the farthest spaceprobe from Earth, we instead  sent “the golden record”…

The "Golden Record" (click to hear) riding on the Voyager spacecrafts includes "The Sounds of Earth". The cover still includes the location of Earth relative to nearby pulsars...but without the naughty pictures.

…which sends our regards with more puritanical messages.  The record is our ultimate mix tape to our alien friends.   If we humans were to launch such a space probe now, I fear it would only have a golden MP3.  Voyager 1 has left the Solar System and is about 110 times further than the Earth is from the Sun and is our most distant space probe.  It will leave our solar system around 2015 and carry out message into interstellar space.

But as Steven Hawking points out, this might not have been such a good idea.  Just ask the ancient Aztecs how much they benefited from the visits of the Spanish explorers.   Even if we are visited by a species that is not violent, visitors  may inadvertently bring microbes we’ve never been exposed to before that wipe us out.    This may even be an inevitable by-product of all such contacts.   If you haven’t read it, I highly recommend the masterpiece Guns Germs & Steel written by Jared Diamond (also at UCLA) who gives a scientific basis to the unfolding of such historical events.   But the sword cuts both ways…  In H.G. Wells’s War of the Worlds, it is our own microbes that ultimately killed the Martian visitors.

So it was the location of a new pulsar, a new neutron star, that Elizabeth Plimpton had written on her hand for tonight’s episode.  A brand-new one  (a “Soft Gamma-ray Repeater” at RA 4h40m, Dec 55035′, which is effectively its longitude and latitude on the sky) was announced on the  The Astronomer’s Telegram before the episode was taped.   In another easter-egg to the High-Def enabled,  note the shout-out to Brian Greene’s excellent popular science book, in the title of Dr. Plimpton’s book:  The Effervescent Universe.

No matter how much we hide, our radio and television transmissions are already giving us away, at the speed of light.   Even tonight’s episode is already beyond Mars.   The extra-terrestrials can easily find us, and may already be on their way.

19 Responses to “S03E21: The Plimpton Situation”

  1. anon Says:

    Just as the spinning lamp in a lighthouse produces a flash of light to those at see

  2. Ben Says:

    I was really hoping tonight’s post would be on the extragalactic distance ladder. Neutron stars are good, too.

    • David Saltzberg Says:

      Yeah, after watching the show again, I think that would have been better.

  3. threeoutside Says:

    I for one got a big kick out of the sexually adventurous female science geek (I’m female, btw). I was more concerned that young, shy boys might think guzzling NyQuil would make them confident with women – but then, I suspect if they tried it, it would just conk them out like it does me.

    • Tony Says:

      threeoutside Says:”I for one got a big kick out of the sexually adventurous female science geek”

      It’s a terrible, terrible thing, when you consider popular culture. There’s a big problem in convincing smart young women that they are welcome in science fields, and this extends all the way down to influences in elementary school. Some of us have been working hard in outreach projects, to try to change these perceptions. It’s an absolute travesty to represent a top female scientist as a sexually promiscuous nutcase. It’s basically reinforcing the wrong idea that science is a man’s world, and women will be their toys. Saltzberg doesn’t have a clue about the cultural damage that these representations can cause.

  4. wsa Says:

    Good suggestion, Guns Germs and Stell is one of the best books I’ve ever read

  5. Uncle Al Says:

    About 5 billion years from now, after its hydrogen is used up

    Earth has 1.36 megayears remaining, tops.

    If New World indigens had shouldered their RPGs when Columbus showed… A civilization is begging to be stomped if it diverts its resources to genetic, developmental, and behavioral trash; reproductive warriors, religious hind gut fermenters, drug addicts, Enviro-whiner Luddites; the stupid, the pathetic, and the Officially Sad.

    America did not save WWII Europe as morality. Agricultural backwater America plundered the entirety of German industry: Otto Ruelen, Ruhrchemie A.G., and Technical Advisory Committee Report A1ML-1 (declassified).

    Be inhospitable to organized strangers.

  6. jg Says:

    Wow – as Penny would say, whack-a-doodle!

  7. jackd Says:

    The alien disease scenario doesn’t work.

    Most diseases don’t cross from one species to another.

    As Diamond lays out in G.G.&S., the diseases that depopulated the Americas were the product of large numbers of humans living in close quarters, along with their livestock. Bacteria and viruses had ample opportunity to mix and jump from species to species. But we are talking about diseases jumping mainly from one large mammalian species to another, and in some cases between mammals and birds. The underlying physiology is very similar.

    A space alien is going to come from a completely different evolutionary line. Compared to an alien, a black widow spider is your cousin and pangolin might as well be your brother.

    Think of it this way: If you’re confronted with a spiny monstrosity from the vicinity of a black smoker, you might worry about it biting or clawing you, but you don’t worry about catching its version of the measles.

    • kcs_hiker Says:

      might take a look at the excellent book “Parasite Rex” by Carl Zimmer

  8. What happens to forces inside an atom when a proton is added? What if a neutron is added? | TV drama Says:

    […] S03E21: The Plimpton Situation « The Big Blog Theory […]

  9. Dennis Gorelik Says:

    1) How fast would sun expand to Venus’s orbit?
    I doubt it would take just a few seconds as this animation shows

    2) If produce Helium->Carbon&Oxygen fusion produces so much energy — why it didn’t start yet?

    • David Saltzberg Says:

      1) That was a “time lapse” movie. The transition from a “main-sequence” star (what the Sun is now) to Red Giant takes about 100 million years.

      2) The hydrogen and carbon nuclei have more protons in them (2 and 6) than hydrogen, only 1 proton. So there is a larger electrostatic repulsion between helium nuclei than hydrogen. . While the hydrogen is fusing into helium the temperature and density of the star’s core, 10 million degrees kelvin, are not high enough to overcome this repulsion between helium nuclei so they generally are never close enough to fuse. But after the hydrogen “burns out”, the stellar core contracts due to gravity and becomes hotter and denser, eventually enough, 100 million degrees kelvin, to start fusing helium into heavier elements.

  10. Dennis Gorelik Says:

    1) If it takes 100 million years to transform from “main-sequence” start to Red Giant star, then advanced enough civilization would be able to move Earth to the higher solar orbits, right?

    2) These are interesting and quite consistent explanations of how internal star processes work out.
    Gravity vs temperature balance is quite logical.
    “Higher protons number -> higher electrostatic repulsion -> higher fusion temperature” chain is logical too.
    When (how many years ago) this theory was developed?

    • David Saltzberg Says:

      1) It would take an enormous energy to move Earth in its orbit. Perhaps an easier option would be to move all life and some water to Mars or Ceres. See “When Worlds Collide” (1951), on of my favorites on the 4:30 movie when I was a kid.

      2) It took a half-century of measurements and theory to understand how stars shine and evolve. A major step, around 1910, was measuring the properties of many stars and placing them as points on a scatter plot of luminosity vs. temperature. This famous plot, is now called the Hertzsprung-Russell diagram. A star will be in a different location on this diagram as it ages. The HR diagram lends some order to what is the zoology of stars which Arthur Eddington used to develop models of stellar structure. This was particularly impressive since nobody yet knew where stars’ energy came from. By 1920 Eddington understood how nuclear energy could be the energy source based on Einstein’s E=mc^2 and guessed correctly that it was the fusion of protons into hydrogen that dominated. In the late 1930’s as more nuclear physics was understood as a result of data from the cyclotrons of the world, Hans Bethe and others proposed at least two of the main nuclear reactions that could fuel stars. The measurement of neutrinos from the Sun begun by Ray Davis in the 1960s indicated that the main nuclear reaction in our Sun was the fusion of hydrogen into helium. Modern studies use helioseismology to understand the finer details of the structure of the Sun.

    • feldfrei Says:

      Ad (2): In addition to David’s reply I like to mention the work by Fred Hoyle (summarized in the 1957 review paper by Burbidge, Burbidge, Fowler and Hoyle) – see here:

      Concerning solar (and stellar) neutrinos: Contemporary neutrino experiments are able to detect almost completely the solar neutrino flux:

      Neutrinos in general play an important role for a star’s stability: they provide efficient cooling of the core due to their negligible interaction on the way out. But I’m sure David can tell you more profoundly about that.

  11. Tradução: “S03E21: The Plimpton Situation (A Situação de Plimpton)” « The Big Blog Theory (em Português!) Says:

    […] feita por Hitomi a partir de texto extraído de The Big Blog Theory, de autoria de David Saltzberg, originalmente publicado em 10 de Maio de […]

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  13. Plimpton situation | Alatisedesigns Says:

    […] S03E21: The Plimpton Situation « The Big Blog TheoryMay 10, 2010 … In the music world, the death of a star is precipitated by sex, drugs and rock-n-roll. In the Universe, the death of a star is precipitated by … […]

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