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Space Science

Two Stars Collided And Solved Half of Astronomy's Problems. Now What? (fivethirtyeight.com) 171

"It's hard to overstate the enormous leap forward that astronomy took on August 17, 2017," reports an article shared by schwit1: On that day, astronomers bore witness to the titanic collision of two neutron stars, the densest things in the universe besides black holes. In the collision's wake, astronomers answered multiple major questions that have dominated their field for a generation. They solved the origin of gamma-ray bursts, mysterious jets of hardcore radiation that could potentially roast Earth. They glimpsed the forging of heavy metals, like gold and platinum. They measured the rate at which the expansion of the universe is accelerating. They caught light at the same time as gravitational waves, confirmation that waves move at the speed of light. And there was more, and there is much more yet to come from this discovery... "Now it's a question of, do we have the right instrumentation for doing all the follow-up work?" said Edo Berger, an astronomer at Harvard who studies explosive cosmic events. "Do we have the right telescopes? What's going to happen when we have not just one event, but one a month, or one a week -- how do we deal with that flood...?"

The August 17 gravitational wave gave astronomers a glimpse at an entirely different universe. For most of history, they've studied stars and galaxies, which seem static and unchanging from the vantage point of human timescales... But GW170817 revealed a universe alive, pulsating with creation and destruction on human timescales... [T]he event itself unfolded in less than three human-designated weeks. This faster timescale is "pushing the way astronomy is done," Berger said... In space, the Fermi space telescope glimpsed a burst of gamma radiation. Within an hour, astronomers made six independent discoveries of a bright, fast-fading flash: A new phenomenon called a kilonova... Nine days later, X-rays streamed in, and after 16 days, radio waves arrived, too. Each type of information tells astronomers something different. Richard O'Shaughnessy, an astronomer at the Rochester Institute of Technology, describes the discovery as a "Rosetta stone for astronomy."

"What this has done is provide one event that unites all these different threads of astronomy at once," he said. "Like, all our dreams have come true, and they came true now..." Thanks to the August 17 event, astronomers now know what to look for. Soon, they will be able to sift through an embarrassment of neutron-star mergers and other phenomena... And they are talking about how to turn their eyes to the sky, at a moment's notice, the next time the universe throws something big their way. "It's a wonderful time, it's a terrifying time," O'Shaughnessy said. "I can't really capture the wonder and the horror and glee and happiness."

Two Stars Collided And Solved Half of Astronomy's Problems. Now What?

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  • by chromaexcursion ( 2047080 ) on Monday December 04, 2017 @12:45AM (#55670769)
    well a couple years old. but that's old in gravity
    • The "forging of heavy metals, like gold and platinum" is old news too. Gold round the outside, tungsten on the inside, and hey presto, one 100% pure RBC or Credit Suisse gold bar, all the way from China. You don't need neutron stars for that, just Alibaba.
    • by habig ( 12787 )

      well a couple years old. but that's old in gravity

      Not quite... a couple years ago, the gravitational waves were observed. The theory says they should be traveling at "c", but there was no way to check that this was true.

      This time, seeing light at almost the same time as the GWs is an observation which says "yeah, that theory about GWs moving at the speed of light is pretty darn close to spot on". That's what the article was getting at.

  • the densest things in the universe besides black holes.

    People get immune to click-bait hype. Say "the second densest things in the universe" instead.

    • by Anonymous Coward

      It's also wrong. The singularity in a black hole is dense, but usually the term "black hole" is used to describe... well, everything from the black part inwards. The schwartzchild radius (the radius of the event horizon) increases linear with mass, as opposed to the cube-root scaling that solid objects have. A black hole with a radius equal to average orbit of Saturn has about the same density as atmospheric air.

      • Is there a "singularity inside a blackhole"? I would think it is a different kind of physics that happens. But I don't know if there are any definite answers.
        I think there is some relation between what happens inside blackholes and the big bang. The Schwartzschild radius of the known universe is to close to the size of it
        • by ShanghaiBill ( 739463 ) on Monday December 04, 2017 @02:56AM (#55671011)

          Is there a "singularity inside a blackhole"?

          Perhaps. But it is not a falsifiable hypothesis. We don't know, and we don't know if there will ever be a way to know.

          • Is there a "singularity inside a blackhole"?

            Perhaps. But it is not a falsifiable hypothesis. We don't know, and we don't know if there will ever be a way to know.

            I think it is. Last I read, the math of how we currently understand things indicates that a black hole spinning fast enough (a Super Extreme Kerr Object ) would provide a naked singularity that would be observable in some manner (eg gravitational lensing). Many physicists dislike the idea of naked singluarities, and at this level we might not even be sure we have the math correct. However, if we found a black hole/object that had those qualities, it certianly would answer many of those questions or at least

      • by ShanghaiBill ( 739463 ) on Monday December 04, 2017 @03:12AM (#55671057)

        A neutron star has a density of roughly 1e14 gm/cm^3.

        A black hole the mass of the earth would have a radius of about 9mm and a density of about 2e27, ten trillion times denser than a neutron star.

        A black hole the mass of the sun would have a radius of about 3 km, and a density of about 1.8e16, a hundred times denser than a neutron star.

        A black hole with the mass of our galaxy would have a radius of about 0.2 lightyears, and a density less than air.

        A black hole with the mass of the known universe would have a radius of 13.7 billion lightyears, and a density far less than the highest vacuum that humans have ever produced.

        • by dargaud ( 518470 ) <slashdot2 AT gdargaud DOT net> on Monday December 04, 2017 @03:21AM (#55671071) Homepage

          A black hole with the mass of the known universe would have a radius of 13.7 billion lightyears

          ...so, the radius of the observable universe ! Is there some deeper meaning to this or is that just a coincidence ?

          • by ShanghaiBill ( 739463 ) on Monday December 04, 2017 @03:57AM (#55671123)

            ...so, the radius of the observable universe ! Is there some deeper meaning to this or is that just a coincidence ?

            It is not likely a coincidence. As an object approaches a blackhole's event horizon, any light it emits undergoes a redshift, and the wavelength gets longer and longer the closer it gets. As it crosses the event horizon, the wavelength goes to infinity, and it is no longer observable. This is exactly what also happens at the edge of the observable universe. If the Schwarzschild Radius of the universe was larger, then we should be able to see further out, and the observable universe would be larger as well.

             

            • We could measure radiation of infinite wavelength if only we had universal ground.

              • by WallyL ( 4154209 )

                Universal ground?! I'm still looking for the universal power port, two- or three-pronged!

            • by rjh ( 40933 )

              In a word, "no".

              Within the event horizon, there is literally no path 'outside'. It isn't that getting there involves an infinite redshift: it's that there is literally no geodesic leading out. Within the event horizon space twists in on itself such that all directions lead deeper inwards towards the singularity.

              You have tremendous freedom to move about in time, but your freedom to move about in space gets sharply curtailed. It's exactly the reverse of the spacetime situation outside the event horizon, wh

            • So the universe is definitely inside a black hole?
          • Matter falls into a black hole and leaves one universe. In another universe a big bang happens as that universe is formed. So universes bud off from each other, and the budding point is a black hole.

            • Re: (Score:2, Insightful)

              by Anonymous Coward

              Matter falls into a black hole and leaves one universe. In another universe a big bang happens as that universe is formed. So universes bud off from each other, and the budding point is a black hole.

              Cool. Now prove it.

          • ...so, the radius of the observable universe ! Is there some deeper meaning to this or is that just a coincidence ?

            No. We are living inside a black hole.

            Universe is all there is. So light can not escape The Universe, wherever it goes, no matter how far, it is still the Universe. That is the definition of black hole, a body from which light can not escape. QED.

            • Not QED. There doesn't appear to be any matter or energy falling in which is what we would expect if the universe was a black hole.

              Then there is the whole other problem of the universe expanding vs. black holes evaporating.
              • That is because there is no "outside" from which energy/matter will fall in. If you can see matter falling in, promptly the observable universe will expand to include the source too!
          • by donaldm ( 919619 )

            A black hole with the mass of the known universe would have a radius of 13.7 billion lightyears

            ...so, the radius of the observable universe ! Is there some deeper meaning to this or is that just a coincidence ?

            The radius of the known universe is 46.6 billion [wikipedia.org] light years, although the age of the universe is estimated at 13.799±0.021 billion years. You also have to remember that Universe has been expanding since the "big bang" so obviously the known universe will have a larger radius than 13.8 billion light years.

          • by Bengie ( 1121981 )
            The observable Universe has a radius of 46.5 billion lightyears. You forgot about the acceleration of the expansion of space-time.
        • by DrTJ ( 4014489 )

          How does "far less than the highest vacuum that humans have ever produced" compare to the density of our universe, if dark matter (and energy?), vacuum energy/particles and fields, and other stuff, is taken into account? Would the vacuum catastrophe gap the difference?

          So, so..... if comparable, could that mean that the observable universe is situated inside the event horizon of a (rather large) black hole?

          Are the inflation/expansion/acceleration/red shift/microwave observations compatible with such an arran

        • by Immerman ( 2627577 ) on Monday December 04, 2017 @10:01AM (#55671953)

          That seemed so improbable that I figured you must have slipped a decimal pace somewhere and double-checked your work. Looks good though.

          Here's the math for anyone interested

          Schwarzschild radius r = 2MG/c^2
          Volume of a sphere = 4/3*pi*r^3

          density = M / [4/3*pi*(2MG/c^2)^3] = M * 3/4pi * (c^2 / 2MG)^3 = 3/32pi * c^6/(G^3 M^2)

          Galaxy Mass ~~= 10^12 * M_sol (@ 2*10^30kg) = 2*10^42kg
          black hole density = 3/32/pi*(300,000,000 m/s )^6 / (6.674×1011 m3kg1s2)^3 / (2*10^42kg)^2
            ~= 0.0008 kg/m^3

          • by e r ( 2847683 )
            So, the speed of light is basically the speed of causality, right?
            And the definition of a black hole is that light can't escape it, right?
            This means that it's impossible for something inside a black hole to affect anything outside a black hole, right?
            So then it's utterly impossible for our universe to ever affect anything outside it, right? Because not even light can escape the Schwarzschild radius of our universe, right?
            And the converse would also be true: other universes couldn't affect ours.
            So the m
            • by Immerman ( 2627577 ) on Monday December 04, 2017 @01:35PM (#55673753)

              Right
              Right - mostly. Though things like Hawking radiation can "escape", and there may be geometric oddities that allow information to escape as well
              Getting iffy - it's not altogether clear that the "inside" of a black hole even exists to begin with - some theories have all inflow stop at the the event horizon itself, from where it could theoretically escape. All we know about the "inside" of a black hole, is that normal physics doesn't work there.
              Nope - you're assuming our universe is a black hole or otherwise has an event horizon.
              Nope - one of the defining qualities of (many classes) of alternate universes is that they have fundamentally different physics.
              Nope.

              Well,it depends on the *specific* multiverse theory you're referring to. There are a *lot* of different multi-universe theories, and many of them may be true simultaneously, giving rise to several fundamentally different classes of alternate universes.

              Some are indeed a little "unscientific" in the sense that they could not be directly tested - such as the idea that our universe is one bubble among countless that formed during the inflationary phase of the universe, in which case (barring FTL) we can never contact any others, because we're all sharing the same coordinate system, and the boundaries of all our universes are expanding at almost lightspeed, while the space between them is still inflationary and expanding much faster than light. We could however conceivably create a "child universe" based on the same principles - though doing so would essentially create a new big bang, destroying everything in the observable universe as the new one expanded at light speed converting false-vacuum to new mass-energy. There's also the possibility that we could detect the "fingerprints" of early shockwaves within such a primordial bubble universe, which would validate the theory, but not provide any mechanism for inter-universe contact. I.E. the theory could be validated, but still be useless.

              Many other theories postulate that our 4-dimensional universe is embedded in a multi-verse with a higher-order geometry, and that other universes (4-D or otherwise) are likewise embedded. Picture many sheets of infinitely thin paper floating in a pond as an analog for 2D universes in a 3D multiverse. In which case contact between such universes are theoretically possible if we could figure out a way to send signals in directions we're not yet aware of. Impossible to test today, but not fundamentally unscientific. And unlike universes which exist within the same 4D-space as ours and thus must lie somewhere beyond the bounds of the observable universe, parallel universes might be arbitrarily close. In fact, there's currently work being done to look for evidence of our universe colliding with others - an event which could occur anywhere in our universe since unlike the edges of a bubble universe, higher-order edges are omni-present.

        • by mccrew ( 62494 )
          Question: when you say density, are you referring to average density over the entire volume? Shirley, the density is not uniform?
        • A black hole with the mass of the known universe would have a radius of 13.7 billion lightyears, and a density far less than the highest vacuum that humans have ever produced.

          Wait, what? Then how is our universe different from a black hole? Given that it apparently has the same size, mass, and density...

    • by Anonymous Coward

      Say "the second densest things in the universe" instead.

      You version contains less information.

  • by SuperKendall ( 25149 ) on Monday December 04, 2017 @01:37AM (#55670891)

    One of the great results of this flood of unified information, is that it seems like it may help a lot in analyzing previously collected data - either looking for particular events or knowing how to filter out some cosmic noise that may be obscuring other things.

    The most exciting thing long term to me, is a better ability to determine in the end what might be the most appealing interstellar targets to send manned or unmanned craft to explore. I'll be long gone but it's nice to think about.

  • by Kohath ( 38547 ) on Monday December 04, 2017 @02:29AM (#55670961)

    better lead to more accurate horoscopes.

    • Maybe this is the dawning of the Age of Aquarius!
    • All astronomically accurate horoscopes are themselves completely accurate, but usually begin and end with "something will happen today"

      Very occasionally they may be further clarified with some details like "A large meteor impact will ignite global firestorms and likely trigger a 'nuclear winter'", or "Much of the planet's surface will be incinerated by a nearby supernova", but those are rare enough that there weren't any (human) astronomolgers around to make the prediction last time.

      • by Kohath ( 38547 )

        "something will happen today"

        Thanks. I will prepare. You didn't even need to know I'm a Capricorn! This new insight into the stars is amazing.

  • A sample of one (Score:4, Interesting)

    by petes_PoV ( 912422 ) on Monday December 04, 2017 @03:36AM (#55671095)

    In the collision's wake, astronomers answered multiple major questions that have dominated their field for a generation

    So the scientists have "solved" half of their research questions.

    If I was an astrophysicist I would be rather worried about my future job prospects at that announcement. Though I would be more concerned with the sloppy science behind doing a single experiment and assuming that every next time it repeats, the results will be the same.

    I would be fervently hoping that the next time there is a neutron star collision, the data that comes in is very, very, different. Thus showing that all this conjecture means we don't really understand those "major questions", after all. Predictable science is so very dull.

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      If something very different happens the next time two neutron stars collide, that just means there are different types of neutron start collisions. And that's not going to be a surprise, any more than it would be surprising that there could be different types of supernovae or different types of automobile collisions. The exact behavior may depend on the rotational speeds, masses, and so on.

      If the next collision is different, maybe they'll call the last one a Type I and the next one a Type II. They'll say th

    • The usual result of questions being answered in science is the discovery of new questions,
      Thus Isac Newton could say he accomplished much because he stood on the sholders of giants,

    • Are you assuming there's a finite amount of things we aim to analyse and understand? I wouldn't worry.

      • by Kjella ( 173770 )

        Are you assuming there's a finite amount of things we aim to analyse and understand? I wouldn't worry.

        In a particular field? Sure. When did we last add any element to the periodic table? Discover a genuinely new chemical reaction? Not that it hits a brick wall or anything, but without producing any significant new science funding will eventually try up. Same with manufacturing, I'm sure we'll always want something more. But not necessarily the product you make.

        • When did we last add any element to the periodic table?

          2016. Four new elements.

        • When did we last add any element to the periodic table?

          That is discovery based, not work based. There are still very many people working in the field looking for new elements etc. The same goes for the rest of your post. Absence of discoveries doesn't mean absence of work in the field.

    • by wbr1 ( 2538558 )
      This is a pretty weak argument, and the same one that Lord kelvin is falsely attributed to have had. Answering questions often raises more than were answered. there will always be research to do as long as there are minds to do it.
      • Not necessarily - we may eventually develop such an accurate model of the universe that there are no longer any measurable inconsistencies to drive further research.

        At that point all that's left is engineering and "stamp collecting" - exploring and cataloging new locations, organisms, etc. And barring FTL even that will eventually become impossible as the expansion of the universe carries the last of the unexplored stars beyond the limits of the observable universe.

    • If I was an astrophysicist I would be rather worried about my future job prospects at that announcement. Though I would be more concerned with the sloppy science behind doing a single experiment and assuming that every next time it repeats, the results will be the same.

      I can tell from this post that you wouldn't be an astronomer, so you can rest in peace on that front.

      Slow dissolve.

      Imagine, if you will, writing those exact thoughts back in 1968. (And why not?—your objections are perfectly generic.)

      SL [sigmapisigma.org]

    • If I was an astrophysicist I would be rather worried about my future job prospects at that announcement

      Why? It does not follow. An astrophysicist would know all the planetary positions well, and has studied the effect of Saturn moving into the seventh house or whatever better than any one. So they know exactly what to do, they know exactly what would happen. That is why you find them to be the richest and most influential persons in the world.

    • It seems that every time I've seen scientists talk about a solution to a problem, they say that it spawns more questions. Humans seem to like to push limits.

  • âoe [T]he event itself unfolded in less than three human-designated weeks.â

    Unless another species has defined weeks (and in a conflicting manner), I donâ(TM)t think we really need to specify that the weeks were human-designated.

    Cthulhu out.

  • ... two neutron stars, the densest things in the universe besides black holes.

    ... the second most dense things.

  • I remember there was some talk of gravity waves being a FTL phenomenon, which could potentially allow for FTL communication...so much for that.

    • Not to mention warp drive will only work at light speed. Better than what we have now, but still a long time to get anywhere.
    • I remember there was some talk of gravity waves being a FTL phenomenon,

      Well, that is still on the table as a possibility. As long as the speed difference is less than about 1 part in 10^18.

  • by edittard ( 805475 ) on Monday December 04, 2017 @02:57PM (#55674391)

    the densest things in the universe apart from black holes and slashdot editors.

    FTFY.

    Actually, I'm not sure about the black holes.

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