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Mini-Black Holes and Stars Winking Out

  1. Feb 17, 2007 #1
    Isaac Asimov, in his 1979 book A Choice of Catastrosphes: The Disasters That Threaten Our World, raised the possibility that mini-black holes created with the Big Bang may burrow into stars and cause them to wink out (pp. 92-96).

    Stephen Hawking in 1974 suggested that (to quote Asimov) "... in the first moments of the formation of the universe, innumerable black holes of all masses from that of a star down to tiny objects of a kilogram or less" were produced. The smaller ones Hawking dubbed "mini-black holes."

    I have two questions related to the above:

    1) What is the current thinking about mini-black holes, including the creation of black holes of any size or mass with the Big Bang?

    2) Has anyone seriously looked for missing stars?

    WRT (2), astronomers constantly search for any unusual variation or brightness (e.g., supernova) in any stellar object. Some researchers have also looked for brown dwarfs eclipsing background stars in the Milky Way or the nearby companion galaxies.

    However, has anyone actively compared past and current surveys of star fields for missing stars?
  2. jcsd
  3. Feb 17, 2007 #2
    can a really small hole be black??
    as it needs a lot of mass to trap light
    and kilo is not enuff no matter how small and dence
    or even a solar mass

    can a small BH eat a star?
    wouldn't it just pass thru eating some but not a lot of mass
    and keep going at about the same speed it came with
    unless the BH was really moving slow and is trap in a inside the star orbit

    if a BH did eat a star don't we get a light show pluss X-rays
    kinda like a mini quasar? and thats hard to miss
  4. Feb 17, 2007 #3


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    It seems the smallest mass needed for a mini BH would be in the order of Planck mass.
  5. Feb 17, 2007 #4
    No matter how small a singularity may be, it would be black, just on a much smaller scale. Regardless of its initial size, it would grow as it comes into contact with matter. If a mini-black hole existed within our solar system, it would itself not likely be visible but only discernible through its gravitational interactions with the members of the solar system.

    Yes, depending on how fast it is moving relative to the star. If it is fast moving and strikes a glancing blow, it probably would not do serious, lasting damage. If it is fast moving and punches through the nuclear center, it could severely disrupt if not extinguish the fusion process there. The star may take some time to recover, during which interval the star's energy output would be substantially reduced.

    If the black hole is slow moving and did become trapped in the nuclear center, then it may well consume the star, and the star would fade out, quite literally here today, gone tomorrow. And it is precisely for that scenario that I wonder if anyone ever checked for missing stars.

    The light show occurs with rapidly spinning black holes around which an accretion disk forms. It may be a necessary prerequisite for black holes of any size to be rapidly spinning, but I do not know for sure. If that light show is taking place within a star, it won't be visible. See, for example http://antwrp.gsfc.nasa.gov/apod/ap951226.html" [Broken].
    Last edited by a moderator: May 2, 2017
  6. Feb 17, 2007 #5
    X rays will get out as will other effects
    remember the hole is small and eating slowly
    Last edited by a moderator: May 2, 2017
  7. Feb 17, 2007 #6


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    Not quite. You have to take Hawking radiation into consideration. The smaller the black hole, the greater the output of Hawking radiation and the greater the hole's Hawking Temperature.

    For example, a mini-black hole with the mass of 2e19 kg (about the mass of the Saturn satellite Hyperion) would have a Hawking temp of around 6000°K, which is close to the surface temp of the Sun. It would actually glow in the visible light spectrum.
  8. Feb 18, 2007 #7


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    And Janus pointed out a compelling argument against miniature black holes - there are none in the 'hood'. Hawking has also backed off this prediction by correctly noting the gamma ray background radiation is insufficient to support the existence of such objects in meaningful quantities. BTW, the planck mass black hole eating the earth is a preposterous idea. First of all, it would evaporate almost before it formed, second, its gravitational attractive force would be exactly that of a planck mass - immeasurably insignificant.
  9. Feb 18, 2007 #8
    Chronos how could a planck mass black hole be black
    I understand there dought they exist
    and may not live long if they do
    but how can a small mass be black [not allow light to excape]

    and if in a billion to one chance
    a black hole was traped inside a star
    what would we see happen
    mini quasar? x-rays ? nothing?
  10. Mar 1, 2011 #9
    "2) Has anyone seriously looked for missing stars?"

    There a report exists which describes a German star catalog
    of the 19th century with hundred thousands of cataloged
    stars a n d the missing of more than 70 stars.

    Star catalogue: Bonner Durchmusterung, see
    Documentation for the Computer Readable Version
    W.H. Warren, p. 12, 13, Table 9.
    The missing stars are listed by the names of
    the catalogue-entry.
  11. Mar 1, 2011 #10


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    Black holes are misunderstood and ascribed mythological powers in the popular press. The LHC will not cause the demise of earth by producing tiny black holes that sink to the core of the earth and eat it from the inside out. Earth has been bombarded by high energy cosmic rays since it formed. The energy of these particles make LHC energies look like an ice cube in a blast furnace. However many tiny black holes were created by these monumental collisions, earth has not yet been consumed.
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