Follow Slashdot blog updates by subscribing to our blog RSS feed

 



Forgot your password?
typodupeerror
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×
Space

It's Official: LIGO Scientists Make First-Ever Observation of Gravity Waves (economist.com) 460

A few days ago, we posted reports that a major finding -- the discovery of the long-predicted gravity waves -- was expected to be formally announced today, and reader universe520 is the first to note this coverage in the Economist : It is 1.3 billion years after two black holes merged and sent out gravitational waves. On Earth in September 2015, the faintest slice of those waves was caught. That slice, called GW150914 and announced to the world on February 11th, is the first gravitational wave to be detected directly by human scientists. It is a triumph that has been a century in the making, opening a new window onto the universe and giving researchers a means to peer at hitherto inaccessible happenings, perhaps as far back in time as the Big Bang. Reader DudeTheMath adds: NPR has a nice write-up of the newly-published results: "[R]esearchers say they have detected rumblings from that cataclysmic collision as ripples in the very fabric of space-time itself. The discovery comes a century after Albert Einstein first predicted such ripples should exist. ... The signal in the detector matches well with what's predicted by Einstein's original theory, according to [Saul] Teukolsky [of Cornell], who was briefed on the results." Update: 02/11 18:08 GMT by T : Worth reading: this letter, inspirational and informative, from MIT president L. Rafael Reif, about the discovery. (Hat tip to Brian Kulak.)
This discussion has been archived. No new comments can be posted.

It's Official: LIGO Scientists Make First-Ever Observation of Gravity Waves

Comments Filter:
  • Cool! (Score:5, Insightful)

    by XXongo ( 3986865 ) on Thursday February 11, 2016 @11:01AM (#51487241) Homepage
    Cool!

    Nobody actually ever thought that gravity waves wouldn't exist-- it's pretty much impossible to come up with a version of gravity that doesn't include waves.

    But it's amazing that we can actually detect it.

    • by bondsbw ( 888959 )

      Wouldn't it have been conceivable, assuming some flaw in the theory of relativity, for gravitational effects to occur instantaneously across vast distances instead of limited by the speed of light (and thus causing propagation in the form of waves)? Or they could have discovered that the waves are different from theoretical predictions in some other way.

      • Re:Cool! (Score:4, Insightful)

        by oh_my_080980980 ( 773867 ) on Thursday February 11, 2016 @11:17AM (#51487339)
        No.
        • Re:Cool! (Score:4, Informative)

          by GameboyRMH ( 1153867 ) <gameboyrmh@gmai l . c om> on Thursday February 11, 2016 @12:09PM (#51487749) Journal

          If it were possible, you could use gravity for FTL communication, possibly even allowing you to violate causality.

          • Re:Cool! (Score:5, Funny)

            by Motherfucking Shit ( 636021 ) on Thursday February 11, 2016 @12:16PM (#51487815) Journal

            I look forward to the day when I can tell Comcast "sorry, I'm switching to gravity."

          • I'll see you and your FTL at Steven Hawking's post-announced party last year.

          • If it were possible, you could use gravity for FTL communication, possibly even allowing you to violate causality.

            What makes you think that this make it inconceivable? I wouldn't find it any more strange than the many-worlds interpretation of quantum theory, and that one has many supporters.

            A lack of causality would mean that our perception of causes and effects is just the biased way we see the world, as a projection of a small subset of events (those with a direct causality relation) within a much more co

            • It's very difficult to reason about the universe without causality. Personally, I would rather not go there, the possible delights of science fiction notwithstanding.

            • by lgw ( 121541 )

              I think you meant to say "Inconceivable? You keep using that word, but I don't think it means what you think it means".

              Many fictional things are "conceivable", but in terms of real science, no one is going to take a casual "general relativity is totally broken" proposal seriously. General relativity has made more and better predictions (and more unexpected predictions) than just about anything. You can doubt any theory, but the more one has proven itself, the higher the bar to claim "but maybe it's total

      • Re:Cool! (Score:5, Insightful)

        by gstoddart ( 321705 ) on Thursday February 11, 2016 @11:22AM (#51487379) Homepage

        Wouldn't it have been conceivable, assuming some flaw in the theory of relativity

        Yes, absolutely.

        The thing here is that to date Einstein has a perfect track record. Which is pretty remarkable.

        To date, everything they've ever tested says that the theory of relativity, as far as we've been able to investigate, hasn't shown any cracks.

        • Re:Cool! (Score:5, Informative)

          by Immerman ( 2627577 ) on Thursday February 11, 2016 @11:50AM (#51487579)

          Well, except for the niggling one where it demands a completely different vacuum energy level than the similarly well-tested theories of Quantum Mechanics.

          It's an odd situation - we have two well-tested and widely accepted theories, neither of which show any significant cracks, but which are utterly incompatible with each other.

          • Re: Cool! (Score:2, Informative)

            by Anonymous Coward

            This has happened in science before, with contradictions between Newton and Maxwell. The whole special relativity thing was the reconciliation.

        • Re:Cool! (Score:5, Interesting)

          by bondsbw ( 888959 ) on Thursday February 11, 2016 @11:52AM (#51487593)

          Absolutely. My point was not so much about refuting relativity completely, but observing (at scales far beyond our normal ability to detect) data that suggests that relativity as we know it is an incomplete theory. Which has already happened, mind you, given that relativity did not at the time fully describe quantum physics and other phenomena.

          But discovering that gravity waves didn't follow the pattern might have made LIGO a modern Michelson-Morley experiment, leading to completely new physics, just as relativity was a better description of gravitation and spacetime than Newtonian physics.

          • by goombah99 ( 560566 ) on Thursday February 11, 2016 @01:18PM (#51488449)

            What's sort of amusing here is that the Michelson-Morley experiment, which is EXACTLY what this experiment is, failed to detect Ether. Yet this experiment is actually detecting ether! it's not the ether distortion MM were looking for which is differences in some vaccum substance that supports electromagnetic wave propagation. Instead it is detecting gravity wiggles in in real matter. Yet those gravity wiggles traveled through vacuum too. And according to general relativity my understanding is that should have distorted the vaccuum too. Thus if MM had had a sufficiently sensitive interferometer they would have detected these and attributed them to Ether fluctuations!

            • by ceoyoyo ( 59147 ) on Thursday February 11, 2016 @01:27PM (#51488565)

              We detected the electromagnetic ether a long time ago. Today we call it "the photon field." If we had a quantum field theory of gravity we'd call the gravity ether "the graviton field" but instead we settle for calling it spacetime.

            • No, the MM experiment was measuring the speed of light in different orientations. Just because both used interferometers does not mean that they are measuring the same thing. If the MM experiment were arbitrarily more precise they would not have detected any change in the speed of light regardless of the orientation of their device, and spacetime fluctuations would have been dismissed as noise, and not particularly significant noise at that.

              You are deeply confused about pre-Einsteinian theories of light and

              • Dude, all both of them detect is phase as a proxy for time delay at arrival. time delay can occur because things got shorter or things went faster. but the experiments are identical in what they actually measure.

              • by lgw ( 121541 )

                There's no difference between "change in speed of light", "change in distance", and "change in travel time for light". They're all the same thing. Don't both instruments detect very small changes in round-trip travel time for light, comparing one direction to the other?

                Sure then 1880s apparatus wasn't going to detect gravity waves, but that's just a matter of sensitivity of the instrument. We still call an electron microscope a microscope.

        • Re:Cool! (Score:5, Informative)

          by buchner.johannes ( 1139593 ) on Thursday February 11, 2016 @12:00PM (#51487671) Homepage Journal

          To date, everything they've ever tested says that the theory of relativity, as far as we've been able to investigate, hasn't shown any cracks.

          That's not quite right.

          - GR breaks down when you go to quantum levels
          - GR does not fully describe black holes (particularly their horizon and the singularity)
          - GR is incomplete with regards to explaining the expansion of the universe (the discrepancy is called Dark Energy)

      • Re:Cool! (Score:4, Informative)

        by joe_frisch ( 1366229 ) on Thursday February 11, 2016 @11:38AM (#51487481)

        Its possible to formulate theories of gravity that don't have gravity waves, but there was already strong evidence of their existence from measurements of the orbit decay of neutron star binaries.

        Direct detection was fantastic - but it confirmed what was already believed to be extremely likely.

      • Yes. Einstein theorized that spacetime is curved around objects, and so an object, once settled, should have this curvature around it rather than a wave to project. That said, it's like ideal gas laws or my economic theories of wealth: everything *approaches* a certain state, but pushing a piston down into a 1L bottle of gas doesn't instantly make tho whole volume obey ideal gas. You get an average, with high pressure at the point you inserted the force, which then reduces as it compresses stuff furthe

        • Yes. Einstein theorized that spacetime is curved around objects...

          More accurately, if you chose to define a geodesic as being the path taken by a light ray, then the space-time coordinate system defined by light rays in the presence of gravity obeys a non-Euclidean metric that is described by the metaphor "curved"-- by which we mean, it has the same geometry as a (Euclidean) curved surface in a higher-dimensional embedding space.

          • We're talking about the fabric of space-time being curved. That means your 3D space is essentially a hyperplane perpendicular to a particular point on a fourth spatial axis. The word "curved" obviously both does and doesn't have the same meaning.

            If you flex a 2D plane and draw a straight line across it, you get a curve because the plane is curved. This is trivially demonstrated by drawing a straight line on a sphere. What you just described is, essentially, a 3D space being curved in the same way, an

      • Would be pretty much impossible since any sort of instantaneous action at a distance implies breaking cause and effect. The speed of light isn't so much the speed limit of light but rather the speed of "causality".
    • I didn't think they existed. After all I can't see them. Unless I can put it in my pocket I don't believe it exists.
    • Re:Cool! (Score:5, Informative)

      by MightyMartian ( 840721 ) on Thursday February 11, 2016 @11:53AM (#51487595) Journal

      Finding them means we can start developing better instruments. Primordial gravity waves are our best shot at understanding the inflationary epoch and understanding the Big Bang itself. This is one of physic's greatest triumphs.

      And, of course, it confirms once again that Einstein remains one of the titans of human thought.

  • * Strong Intergalactic Force, or the
    * Weak Intergalactic Force.

    When are white holes going to be discovered? :-)

  • by damn_registrars ( 1103043 ) <damn.registrars@gmail.com> on Thursday February 11, 2016 @11:03AM (#51487257) Homepage Journal
    Oh, wait, that wasn't LEGO scientists.
  • Fast (Score:5, Insightful)

    by monkeyxpress ( 4016725 ) on Thursday February 11, 2016 @11:05AM (#51487267)
    Wow, this must be a world record for slashdot - the press release only just made it out. Having said that, this was possibly the worst kept announcement in the history of science journalism.
    • You can safely assume that a tremendous amount of people have been sitting on the edge of their seats for this.

      Confirmation of yet another aspect of Relativity is a big deal -- this is a theory with a perfect track record and which pretty much describes almost everything about the universe.

      Disproving any of his stuff would rock the scientific community. Continuing to prove again and again just how right he was? That's worthy of some coverage, and NOBODY who covers this stuff was going to miss it.

      Everybody

    • Wow, this must be a world record for slashdot - the press release only just made it out.

      Holy shit, maybe the new owners are actually accomplishing something!

    • That's OK, we still have four months for the "dust on the detector" story.

      Science is continuous, not discrete - stories that begin with "It's Official" can be safely filed under, "we'll see".

      Which is a Good Thing.

  • Forget hoverboards, we need to start surfing gravity waves.
  • Why this matters (Score:5, Informative)

    by JoshuaZ ( 1134087 ) on Thursday February 11, 2016 @11:13AM (#51487315) Homepage
    This matters for a bunch of reasons. First, it helps close confirm predictions of general relativity. We had a lot of evidence already but more is good. Second, if we get more data we might be able to rule out or narrow down our search space for any eventual quantum gravity theory since they have predictions about how gravity waves should behave (although this would require massively upgrading LIGO). Third, this gives us insight into stellar objects that we normally lack the ability to examine. For example, we don't know much about what the cores of neutron stars are like, but different ideas about them give different predictions about what sort of gravity waves two merging neutron stars will create. So this may give us more data about what exotic objects are actually doing. Fourth, this gives us for the first time a way of getting data from very far away sources that isn't in the electromagnetic spectrum. Right now, we can detect neutrino bursts if they come from a few million light years away but pretty much everything from outside our little galactic neighborhood has to come either from electromagnetic radiation or detecting cosmic rays. But LIGO can already detect gravity waves from events that are a billion light years away. So this gives us a whole new long type of data.
    • Re: (Score:2, Interesting)

      > We had a lot of evidence already but more is good

      Oh come on. We have a lot of evidence that the sky is blue, how much money should be spend on gathering more evidence of that?

      > Second, if we get more data we might be able to rule out or narrow down our search space for any eventual quantum gravity theory

      That would be true if the measurement *disagreed* with the predictions, but it *agrees* with them. That is, this result helps make QG *harder*.

      > Third, this gives us insight into stellar objects

      Oh

      • Re:Why this matters (Score:5, Informative)

        by ganv ( 881057 ) on Thursday February 11, 2016 @12:28PM (#51487899)
        I think you don't understand. We now have an entirely new way to observe what happens in regions of the universe where the mass density is high and changing. In many ways, this is like the first telescope. It is an entirely new way of observing. The reason this is so important is not the single black hole merger they detected. It is because this is the first of what will become a major source of astronomical data. Soon other frequency ranges of gravitational waves will be measurable (see LISA, https://en.wikipedia.org/wiki/... [wikipedia.org]). Just because the first observation agrees with existing theory is no reason to dismiss an entirely new class of measurements as uninteresting.
        • by pz ( 113803 )

          The reason this is so important is not the single black hole merger they detected.

          AND, it was detected during a shake-down run that wasn't intended for scientific investigation. Either they were incredibly lucky, or these things happen all the frelling time, and we're about to view a cacophony of zip/whip/zuups.

          It is because this is the first of what will become a major source of astronomical data.

          Indeed -- one of the unaddresed issues (so completely, blatanly unaddresed that I suspect the scientists involved have been blinded by the success) is using gravity waves for real astronomy. Wait, wait, bear with me for a second; I'm not saying what they did wasn't real astronom

          • by ganv ( 881057 )
            Yes, and gravity wave astronomy could become a hugely important complement to electromagnetic astronomy. Because gravity wave frequencies are set by the motion of mass rather than by atomic (or other) transitions between quantum states of charged particles, gravity waves provide a more direct measurement of the motion of the objects in the systems of interest. So we directly measure the time dependent frequency of one signal and can immediately determine orbital parameters of relatively small objects that
    • Never mind all that, when do we get actual hoverboards (not those fire hazards on wheels we keep seeing in the news)? And Kzinti-style gravity polarizers to replace chemical rockets? And Lift Belts so I can just fly to work above the treetops and skip all the traffic? Don't tell me "it's five years away", we all know what THAT means!
  • The wave motion engine gets built to travel between galaxies to Iscandar and save humanity from the Gamilon radiation bombs.

    https://en.wikipedia.org/wiki/Space_Battleship_Yamato_(spaceship) [wikipedia.org]

  • by nanospook ( 521118 ) on Thursday February 11, 2016 @11:17AM (#51487345)
    It's not something that moves along is it? It's a perceived distortion of time space? I'm thinking of the metaphor of the flat surface with the heavy object in it that shows in 3d how mass would be attracted to mass. So what is a wave? A flexing of space time? or is it time to update the usual way of thinking of it?
    • by JoshuaZ ( 1134087 ) on Thursday February 11, 2016 @11:20AM (#51487365) Homepage
      Essentially a flexing of space, but it isn't easy to visualize. Imagine a circle as a gravity wave goes through it then the horizontal direction will get flattened and the vertical (direction of the wave) will get stretched out, and then the reverse. The actual equations for what it does to an object though are non-trivial.
    • It's not something that moves along is it?

      Err... I think it's like water waves in that sense. No thing is moving in the same direction as the wave. The water molecules only move up and down, but the combined movement becomes this thing we call a wave.

      It's a perceived distortion of time space?

      It's perceived as a change in the distortion of spacetime. I'm not sure if we've been able to measure static distortions of spacetime yet (not directly, anyway; we can see gravitational lensing for example, and of course falling is a direct consequence of spacetime distortion).

      • No thing is moving in the same direction as the wave.

        Not quite an exact analogy. In water waves, an individual molecule moves slightly forward as it goes up and slightly backward as it goes down, following an approximately elliptic path. But yes, it has no mean movement in the wave direction.

        It's easiest to think of a wave as a traveling disturbance.

    • It not that different from an electromagnetic wave (light). With an electromagnetic wave, if you have two charged objects at different locations they will feel a force that causes them to move relative to each other. In electromagnetism you can also detect the motion with one particle because it feels an acceleration.

      With a gravity wave, two massive objects will move relative to each other. Here you can't detect with a single object because it feels no acceleration - the object is in free fall even thoug

  • by avandesande ( 143899 ) on Thursday February 11, 2016 @11:19AM (#51487359) Journal
    Build some more and we can actually pinpoint the origin of the waves.
  • by Thud457 ( 234763 ) on Thursday February 11, 2016 @11:27AM (#51487413) Homepage Journal

    the first gravitational wave to be detected directly by human scientists

    I had to go read the linked story to make sure it wasn't typical /. submitter reading failure.
    Please, The Economist, do tell more, I think you buried the lead there.

    sigh. At least it's not a Forbes link.

    • Its yet another proof of the global alien conspiracy. What else? They are among us. They control us. They will make earth their colony.

    • It's a perfectly cromulent thing to say. We don't know if we're the first scientists to detect these things. We don't know that there are any non-human scientists, and the wording doesn't imply that we do.

  • Could they be used in a directed energy weapon (hey, it's a wave, so it could be focused), or emitted by some kind of bomb?
    • To create significant gravitational waves you need to accelerate extremely compact objects which have nuclear densities up to large fractions of the speed of light. If you can do that you already have a far more powerful weapon than any gravitational waves you might be able to get them to emit.
    • We already have gravity bombs.
  • by Culture20 ( 968837 ) on Thursday February 11, 2016 @11:30AM (#51487437)
    Building blocks of the universe.
  • ...need to figure out a way to surf these waves.

  • to the triggering event and the general direction it came from?

    • the period/ magnitude of the wave tells them distance/time. They don't know the direction though- if they build more detectors they could use accurate timekeeping to find where the source is using a GPS style calculation.
  • by 93 Escort Wagon ( 326346 ) on Thursday February 11, 2016 @11:50AM (#51487577)

    I'll wait for the peer review.

  • I guess I'll be the pedant here :) It's gravitational waves, the name gravity wave is already taken.

  • by Soldrinero ( 789891 ) on Thursday February 11, 2016 @01:05PM (#51488313)
    For those who are interested, the scientific journal has a companion article here [aps.org]. It describes the design and sensitivity of the experiment, as well as some of the context. There is also a link to the actual journal article to the right, but you may need institutional access to download it.
  • by Dr. Spork ( 142693 ) on Friday February 12, 2016 @08:15AM (#51493627)
    When these two black holes merged, three solar masses worth of matter got turned into pure energy, in the form of gravity waves. Compare that to a nuclear bomb, where a mass of about one pea gets turned into pure energy. It's hard to wrap my mind around the scale of this event. But adding to that problem is that this is not your ordinary explosion with a bright flash. So what would happen to objects in the vicinity of this gravity wave "explosion"? Would it tear apart our bodies? Would it destroy planets? Would everything heat up from the friction of relative motion? Or would these waves just pass through us without us noticing?

"How do I love thee? My accumulator overflows."

Working...