Is this mike live?

Rosie asked me on the train back from Marburg, apropos nothing in particular,how much a piece of neutron star the size of a grain of sand would weigh. Does anyone know? Rupert?

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11 Responses to Is this mike live?

  1. Jon h says:

    The usual unit of neutron star weight comparison is the spoonful. At least, that’s how it seems to me.

    So just do a search for neutron start + spoonfull, and then figure out how many grains of sand fit in a spoon, and divide.

    Though I doubt you’ll get a spoonfull value that can be meaningfully divided like that.

  2. Andrew says:

    All the comparisons I can easily find on the web use “teaspoon” as their unit. This is very little help. Do they mean heaped, flat, or rounded? There is a difference of several million tonnes involved.
    “One thimbleful of this stuff would weigh as much as all the skiscrapers in Manhattan!” squeaks an excited set of lecture notes. How much is is that supposed to be? Has anyone a clear idea of how much all the skysscrapers in Manhattan actually weigh? Fortunately, there is also a hard figure: 10^17 kg/cubic metre.

    Assume one grain of sand is a cubic millimetre and, er, I get 10^6 kilos to every grain of sand. Which sounds reasonable, in a mad kind of way.

  3. jonathan says:

    The major variation is not in the the web’s conception of a teaspoon. Flat or rounded is a mass factor of less than two, and even those stupid collectable christening spoon type spoons are probably only half the size and within an order of magnitude the mass of regular.

    The more serious problem is in getting Rosie to specify what she means by sand. According to the Wentworth 1922 phi scale she could be envisaging anywhere in the 60 to 2000 x 10^-6 metre size range, which corresponds to a difference of mass of 4 orders of magnitude. [I got between a thousand and thirty million metric tonnes for a grain of neutron star]. If you could negotiate her down to silt size you might be able to hire a man and van to carry it.

    Once you get this far, you start being amused by the fact that Googling for ‘neutron star teaspoon’ also reveals statements varying by over three orders of magnitude for the teaspoon weight quantity, which is coming I think from density estimate variation. [Precision in theoretical physics is not always all it is cracked up to be, but I don’t know if that is a transmission-to-web error].

    ps to Andrew: I bought Darwin Wars because of this blog. Encouraging, huh? (And I liked Darwin Wars so much I, erm, sat in a Borders play area for an hour reading the Worm book).

  4. jonathan says:

    Rereading that postscript, it sounded unintendedly mean. I loved the real engagement with the science and with the people in Darwin Wars (and the gossip). And I would buy the worm book if it was in a rational medium like paperback.

  5. Andrew says:

    Your chance will come, then, in September. But I have to say that I think there is a hell of a lot more science in the Worms than DW, which is mostly about philosophy. In fact, that’s why I wrote worms: I realised that I had done a whole book on “genes” with no very clear idea of what one loojks like.

    Still, if you hurry, you might well find a signed copy in the Cambridge Waterstones.

  6. Rupert says:

    Sorry, I missed this one. Something to do with another three of my pals getting laid off at work, and my blood pressure being dangeriously raised by the news that those antediluvian apes behind Gateshead Emmanuel College are getting the dosh from Tony to do another six schools. Can we not do something about this?

    In any case, the neutron star material in the grain of sand will be heavily outweighed by the World that’s in there already (assuming it’s even a modest World, such as our own, and clocks in at around 6×10^24 kilo). Blake had no truck with teaspoons, and I feel this is a correct approach.

    R

  7. jonathan says:

    Blake is not a helpful companion in the context of your first point. To Blake, “Newton, Bacon and Locke with their emphasis on reason were nothing more than ‘the three great teachers of atheism, or Satan’s Doctrine’. “, says the Tate.

    He would presumably have more truck with post-Newtonian reason since only by travelling past the grain of sand at the speed of light, could we fit its eternity into an hour as required before the World appears.

  8. Rupert says:

    Nonsense! It’s not the abandonment of reason that exercises me so — I’m all for it. It’s the cloaking of irrationality in the cloth of science that riles this bear and here MC Billy B is, I believe, unimpeachable.

    Which is more than you can say for Ike (*), although he does have the excuse of living in the 17th century before such things were quite so polarised.

    R

    (Newton, not Walton, as I feel I should amplify in this forum. I have no idea what Isaac Walton’s opinion was on the density of neutron stars)

  9. Jonathan says:

    Somewhat suspicious of the fact that two different NASA estimates differ by 900 million tonnes per teaspoon, I did some research on this which actually went as far getting a book out of the library. Answer: (1) it depends where in the neutron star you collect your grain from, and, (2) remarkably, web pages can be wrong.

  10. Jonathan says:

    Somewhat suspicious of the fact that two different NASA estimates differ by 900 million tonnes per teaspoon, I did some research on this which actually went as far getting a book out of the library. Answer: (1) it depends where in the neutron star you collect your grain from, and, (2) remarkably, web pages can be wrong.

  11. Jonathan says:

    Somewhat suspicious of the fact that two different NASA estimates differ by 900 million tonnes per teaspoon, I did some research on this which actually went as far getting a book out of the library. Answer: (1) it depends where in the neutron star you collect your grain from, and, (2) remarkably, web pages can be wrong.

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