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Space

Astronomers Successfully Predict Appearance of Supernova 86

schwit1 writes: For the first time ever astronomers have been able to predict and photograph the appearance of a supernova, its light focused by the gravitational lensing caused by a galaxy and the dark matter that surrounds it: "The NASA/ESA Hubble Space Telescope has captured the image of the first-ever predicted supernova explosion. The reappearance of the Refsdal supernova was calculated from different models of the galaxy cluster whose immense gravity is warping the supernova's light." What makes this significant is that the prediction models were based on the theory of gravitational lensing and required the presence of dark matter to work. That they worked and were successful in predicting the appearance of this gravitationally bent light (bent by the dark matter it passed through) is a very strong confirmation of both concepts.
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Astronomers Successfully Predict Appearance of Supernova

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  • Prediction of What? (Score:5, Informative)

    by tinkerton ( 199273 ) on Saturday December 19, 2015 @07:38AM (#51149461)

    They didn't predict that a supernova was about to happen. They'd already seen the supernova happening in its ghost image created by gravitational lensing. They predicted where another image of the supernova would turn up.

  • by Henning Rogge ( 4024165 ) on Saturday December 19, 2015 @07:51AM (#51149477)

    It is a quite interesting thing being able to "re-watch" a Supernova from the beginning because the light has multiple paths towards Earth so we got a "warning" when it will happen.

    The problem with a lot of Supernova explosions is that we often don't know what happened in the early phase (until it became bright enough to be noticed in wide-field pictures). It is most likely "a little bit" too far away to learn what type of star has exploded, but it still a great opportunity.

    • Re: (Score:2, Interesting)

      by KGIII ( 973947 )

      I'm just waiting for someone to pipe up that DM doesn't exist while not actually knowing what DM is. There are a few people who have valid opinions on it but almost all of the ones that I've noticed don't actually know what it is. (It's not really anything too specific yet, but we've got some ideas and some math. It's a placeholder.)

      • by tomhath ( 637240 )

        I'm just waiting for someone to pipe up that DM doesn't exist while not actually knowing what DM is...(It's not really anything too specific yet, but we've got some ideas and some math. It's a placeholder.)

        Since nobody knows what it is, anyone who says it doesn't exist would not know what it is.

        • by KGIII ( 973947 )

          Sort of true. I mean, yeah, it could turn out to be an effect caused by purple unicorn farts and it would still be dark matter.That's unlikely, and all, but it could happen. Something is causing this effect. Of course, some people seem inclined to not know the difference between dark energy and dark matter but that's a topic for another day.

          I am not a physicist. I am a mathematician. I do find it fascinating but it's just a hobby.

          • It could also be those massive magnetic fields that we know exist but refuse to acknowledge any possible source for.
      • Why would you wait for ignoramus posts? And why tell us that's what you are doing? Starting the argument because no one else yet had? You are nonsense and noise.

        • by KGIII ( 973947 )

          Pfft... Have you not seen the past half dozen, or so, threads where DM was mentioned? I'm awaiting it for the amusement factor. Why else would I be here? You've gotta be new here.

      • I'm just waiting for someone to pipe up that DM doesn't exist while not actually knowing what DM is.

        I seem to recall that nobody knows what dark matter is, thus anyone saying anything about dark matter doesn't actually know what DM is.

        • by KGIII ( 973947 )

          It is just a title to use, a placeholder, to describe the results we're seeing. It could be purple unicorn farts and it would still be dark matter. Though, I presume, they'll change the name if it turns out to be purple unicorn farts. I find the choice of title to be rather silly, it's like the "God Particle" all over again.

    • It is a quite interesting thing being able to "re-watch" a Supernova from the beginning because the light has multiple paths towards Earth so we got a "warning" when it will happen.

      I though we were able to notice supernovas a short time in advance of when they occurred visually because neutrinos from the explosion make it out of the star well in advance of the other stuff. (So we see a few neutrinos and can tell the supernova is about to be visible).

      Can someone confirm or deny? It's been a long time since I took astrophysics.

      • Re: (Score:2, Informative)

        by Anonymous Coward

        We can ... in theory. The trouble is that our neutrino detectors aren't as sensitive as our optical telescopes. We can detect optical supernovae billions of light-years away, but we can only detect the neutrinos from a supernova within a few hundred thousand light-years.

        The most recent supernova that was close enough to detect in neutrinos was in 1987 ( SN1987A [wikipedia.org]). Three detectors spotted neutrinos from it a few hours before the optical supernova, but they only noticed this coincidence after the fact.

        We're

    • There's one thing I don't get: TFA says that "While the light from the cluster has taken about five billion years to reach us, the supernova itself exploded much earlier, nearly 10 billion years ago".

      I think someone's mixing up definitions of time and space here, or getting different reference frames into a tangle, because that doesn't make any sense to me.

      • by Anonymous Coward

        That's perfectly sensible. The cluster is five billion light-years from us, so the light from it has taken five billion years to reach us. The supernova is behind the cluster, at a distance of ten billion light-years, so it exploded ten billion years ago, and the light from it has taken ten billion years to reach us. (Five billion years to reach the cluster, and another five billion years to travel the rest of the way.)

        You can do things in another reference frame, of course, and get different answers, bu

  • by Anonymous Coward on Saturday December 19, 2015 @09:32AM (#51149677)

    ESA Hubble Space Telescope has captured the image of the first-ever predicted supernova explosion. ... What makes this significant is that the prediction models were based on the theory of gravitational lensing and required the presence of dark matter to work.

    The important part here seems like confirmation of testable predictions made by Dark Matter theories. That's how science works: you have to make a falsifiable theory that makes testable predictions. Those predictions are then tested, to lend evidence toward or against the theories. This is key evidence in favor of Dark Matter.

    • I don't see how this supernova business relates at all to Dark Matter. The supernova happened in a galaxy already known to be gravitationally lensed by this other galaxy. Therefore it is predicted to show up in the gravitationally lensed image. The only involvement of Dark Matter is that, yes, we still need it for galaxy gravity to match our estimates of galaxy mass and gravitational strength. Just like it was needed to match galaxy rotation speed and non-supernova gravitational lensing. I mean, I suppose w

    • by HiThere ( 15173 )

      That's probably the most important part, but being able to photograph an entire supernova explosion from slightly before the main event isn't without it's importance.

      I do, however, wonder just how tightly this constrains the properties of dark matter. That could (possibly) be a real breakthrough.

      • by KGIII ( 973947 )

        Nice! That's my thinking as well. This means, at least, that the maths that predict the results of Dark Matter are correct in this instance. This means that we're one step closer to, maybe, getting to figure it out a bit more. I read a bit of a study about some findings of "strands" (I think that's what they were calling them) that were quite close (around the moon) and that we're able to actually see, specifically, where the lensing is happening at it's greatest effect.

        Unfortunately, there has been some se

    • Dark matter has many testable predictions; armchair physicists who think they can second guess professionals only ever seem to know about rotation curves, and smugly decide that they know better.

      Modified gravity only has the benefit of fitting certain observations - it has no theoretical backing. With most current data, modified gravity doesn't fit that well anyway. Its largely out of favour with physicists, only with those people who think that without any formal training in the subject they understand it

  • I wonder whether they could have used modified Newtonian dynamics to have made the same prediction.
    That is to say, I don't see how this prediction leans to either side in the dark matter vs MOND question.

    • by Khashishi ( 775369 ) on Saturday December 19, 2015 @12:32PM (#51150239) Journal

      MOND is largely discredited by the bullet cluster measurements.

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