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Possible Supernova In Nearby Spiral Galaxy 69

Posted by Soulskill
from the sorry-about-your-luck-aliens dept.
New submitter Zburatorul writes "In an electronic telegram to the IAU, an Italian astronomer reports his discovery of a possible supernova (magnitude R = 15) near spiral galaxy M95 on images taken March 16th. Many more independent and confirming observations are trickling in. The Bad Astronomer, Phil Plait, has a more layman-friendly article about it. The bad news: it won't be visible with the naked eye. The good news: it's not going to kill us."
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Possible Supernova In Nearby Spiral Galaxy

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  • by niftydude (1745144) on Tuesday March 20, 2012 @11:17PM (#39423249)
    Hey Bad Astronomer, do you think this has a chance of being a big enough explosion for the LIGA gravity wave interferometers to detect?
  • by Black Parrot (19622) on Wednesday March 21, 2012 @03:56AM (#39424501)

    This has always hurt my brain: from our frame of reference, if this supernova is ~40Mly away, is it happening now or did it happen 40M years ago?

    Well, according to the most popular view of QM, a wave function doesn't collapse until an observation is made. So unless there are alien species that live closer to it and watch the skies, it has spent the last 40My in a superposition of "went nova" and "didn't go nova". So in some sense it "happened" just now.

    Or maybe 40My into the future, since it will take that long for the fact that we have observed it to propagate back to the star.

    Hope that makes you brain hurt less.

  • Re:Relativity (Score:5, Interesting)

    by stevelinton (4044) <sal@dcs.st-and.ac.uk> on Wednesday March 21, 2012 @04:59AM (#39424765) Homepage

    No there really is no absolute present in relativity. We can calculate that this supernova occurred 40 million years ago, simultaneously with some event on Earth, but an alien whose spaceship was flying past Earth 40 million years ago at near light speed and who later sees the light from the supernova would not calculate that those two events were simultaneous. Neither it, nor we, is wrong. Simultaneity depends on how you are moving.

    What relativity does, indepdendently of how you are moving, is divide the universe into five parts:

    * your past -- events from which you could have received a slower-than-light message by now
    * your past light cone -- events from which a light-speed signal is just now arriving
    * your future light cone -- events which might receive a light-speed signal if your send it now
    * your future -- events which could receive a slower-than-light message from you
    * the rest

    No observer will disagree (except by mistake) about which of these parts any given event is in with respect to you.

    The supernova is on our past light cone. In our stationary reference frame it's about 37 million years away, but again, a moving observer would come up with a different number.

  • by msevior (145103) on Wednesday March 21, 2012 @06:00AM (#39425061)

    Back of the envolope calculation follows:

    Distance to SN1987a = 1.9x10^5 light years
    Distance to M95 = 4x10^7 light years

    Ratio of neutrino flux SN1987a / M95 = (1.9/400)^2 = 2.2x10^-5

    Number of neutrinos detected at Kamiokanda from SN1987a = 10
    Sensitivity of Super-Kamiokanda (Super-K) = 20x that of Kamiokanda

    Expected number of nu's from M95 at Super-K = 20x10x2.2x10^-5 = 0.004 :-(

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