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Double Pulsar Discovered

Posted by michael on from the double-your-pleasure dept.

jabberjaw writes "Nature is reporting that a set of two pulsars could be emitting gravitational waves. Einstein predicted the existence of gravitational waves in his general theory of relativity, but a gravitational wave has yet to be detected. Find out more about gravitational waves and pulsars at Eric Weisstein's World of Physics."

24 of 293 comments (clear)

  1. Speed of Gravity by fejikso · · Score: 5, Interesting

    Does someone know if these waves travel at the speed of light? Of course, as predicted by the theory.

    I suppose so... otherwise we could eventually devise faster-than-light communications, and I don't think the Universe is that nice :)

    1. Re:Speed of Gravity by DigiShaman · · Score: 5, Interesting

      This was discussed in a NOVA special about String Theory in The Elegant Universe. You can watch all three hours of the program online for free. I think the part about the speed of gravity (as to if it's effect are instant or at the speed of light) are in the first hour of the program. Check it out here

      http://www.pbs.org/wgbh/nova/elegant/program.htm l

      --
      Life is not for the lazy.
    2. Re:Speed of Gravity by spiro_killglance · · Score: 4, Interesting

      No, entanglement is strange. Entanglement is
      non-local, that is it isn't a property of a
      single particle, its a property of a collection
      of particles. You can't use entanglement to
      send information faster than light, because you
      can't use entanglement to send information at all.
      What you can do is use entanglement to had extra
      information to a classical communication channel.
      If you add to a channel transmitting n-bits of
      information, n entanglement pairs of particles one
      part of each pair at the reciever and one at the
      transmitter, then you can send 2^n bits of information which is fanastic. But without the
      classical channel you can't send anything at all,
      so dispite being non-local, entanglement evades
      brakeing the rule that you can't communicate faster than light.

    3. Re:Speed of Gravity by TexVex · · Score: 4, Interesting
      The Earth is either orbiting the Sun's actual position, or it's orbiting a point that would be about eight minutes in front of the Sun's extrapolated path based on its position and momentum at that given instant.
      What I meant to say here is "or it's orbiting a point that would be the Sun's extrapolated position based on constant motion from its position, direction, and velocity about eight minutes ago." That point won't be exactly where the Sun is now but it will be pretty close.

      That's what I get for trying to discuss something I'm familiar with but not extremely knowledgeable of at 3:30 in the morning.
      --
      Fun with Anagarams! LADS HOST, SHALT DOS. HAS DOLTS. AD SLOTHS, HATS SOLD. ASS HO, LTD.
    4. Re:Speed of Gravity by akruppa · · Score: 4, Interesting

      As for the faster-than-light communications, we could do that with tangled photons. Einstein was troubled by the fact that quantum entanglment causes an instantaneous change across a large distance. It's been used in a large number of sci-fi novels, including Orson Scott Cards Ender's Game series of books.

      The problem with quantum teleportation is that you need to send classical information in order for the receiver to reconstruct the quantum state to be transmitted.

      When Alice prepared her entangled quantum bit with \phi, the state that is to be transferred, Bob's (entangled) quantum bit is in a superposition of states that do not yet reveal any information on what \phi was. Alice needs to measure her \phi and entangled qubit and send that info to Bob, who can then apply some operators on this copy of the entagled qubit and that puts it into the state that \phi originally was in. So the speed of quantum teleportation is actually tied to the speed of classical information transfer, thus limited to the speed of light.

      Alex

      --
      Heisenberg may have been here
  2. detecting gravitational waves? by UPAAntilles · · Score: 3, Interesting

    I would be very suprised if they could actually "prove" the existance of such waves. Gravity is such a weak force compared to the other three (strong, weak, and electromagnetic) that pulsars light-years upon light-years away would be washed out by the gravitational effects of, well, the rest of the universe! There's been conjecture about this for years, and entire theories to try and resolve this problem of no detection (several string theories have been developed around this problem) We've even built miles long observation "tools" (like this one in Livingston, LA). However, if we can solve the background noise radiation, and the pulsars are close enough to earth, and have a large enough gravity, they just might do it! Einstein's theory of general relativity states that two orbiting stars (two orbiting anythings, but stars have a lot of mass and therefore gravity, so it would be pronounced) will 'shed' some of their momentum through gravity waves. The detection of these waves could revolutionize physics! It would allow us to determine the existance of the graviton, and if we ever did that, the world as we know it would change. Because once we pin it down, we can start converting energy to it, and probably start research on a feasible "anti-graviton" of sorts. Warp Drives, here we come! (well, not likely, but a guy can hope)

    1. Re:detecting gravitational waves? by kwpulliam · · Score: 4, Interesting

      "And how would detection of a gravitational wave help advance technology as opposed to pure science?" Well...you generally need the science for the technology. "Pure gravity research is not exactly known for its technological applications" Hmmm. Pure electrical research was useless for centuries, but it's QUITE handy nowadays... I think I'm gonna go turn up the thermostat. Don't prejudge unknown applications. Your grandkids may not comprehend how we lived without it. I'm sure glad I don't have to chop wood, read by kerosene, drive a horse or steam cart, or write this out longhand to a discussion journal and wait 3 months to see it in print.

  3. Gravity doesn't pull, but rather pushes. by DigiShaman · · Score: 3, Interesting

    I've always belived that our concept of gravity is wrong. I think the reason our universe is expanding is not because of "dark energy", but because space is trying to displace a minority substance called matter.

    Imagine if you will that the earth is a bubble in water. The more dense a planet is (or the higher the air pressure is in a bubble), the more effort it takes for space to want to displace that matter. But, what if we could control the "pressure". In other words, what if we could spoof a matter in the form of energy in front of a space craft? Rather then the ship propelling itself through space, you could instead have space push the craft much like the difference in water pressure wants to push an air bubble to the surface.

    --
    Life is not for the lazy.
    1. Re:Gravity doesn't pull, but rather pushes. by pavon · · Score: 2, Interesting

      Interesting idea ...

      If I understand you correctly, you are proposing that gravity is property of space, not matter. In this idea space is attracted to space, and as a result the center of the universe is the center of "space mass", and has the highest amount of space presure. The effect that we see is that matter (which has a lower space-density) is displaced by space away from the center, and towards the outer edges. Is this correct?

      Now this model would (qualitatively at least) predict that space pressure would cause matter to move away from its (spaces's) center, and that space-presure would form planets in spheres (matter bubbles). Where the model falls apart in my eyes is that it does not predict that orbits are possible. Space pressure would not cause two matter bubbles to be attracted to one another over a distance, and that is precicly what we observe in an orbit - one matter bubble has continous force being applied to it in the direction of the other bubble.

  4. Actually you wouldn't notice by DumbSwede · · Score: 3, Interesting
    I think most scientists believe the Sun's gravity will lag at the same speed as light.

    BUT, assume the Sun winked out while it was night for you.

    You wouldn't feel a thing.
    No massive, "Oh, MY GOD we're lurching into space!" That's the whole point of space curved by gravity, you can't tell that you're not traveling a straight line. The weather would goto hell in a handbasket fast from no incoming heat after a few minutes or hours, and of course dawn wouldn't come. There might be some tectonic activity, some isolated magnitude seven and eights here and there, but most likely not immediately.

    No you wouldn't even notice at first as the night hung on forever, and Earth continued on a straight line into the blackness...

    --
    Letter To Iran
    1. Re:Actually you wouldn't notice by bhima · · Score: 4, Interesting
      Actually this was the topic of an old Sci-Fi short story called "A Pail of Air". Basically it was a thought experiment starting with the nemesis theory (Giant dark proto-sun in a highly elliptical orbit which swings by every epoch to cause mass extinctions).

      So Nemesis swings by and strips the Earth off the sun's orbit. The goes dark and cold and there is some tectonic activity. The interesting thing is that the Earth's temperature starts to drop to match the temperature of open space. The oceans freeze and the atmosphere condenses and rains down to the surface, where it forms strata based on what temperature the gas condenses at. To the protagonist goes out side and digs past the CO2 until he finds a strata of O2 and brings a pail of air inside.

      But I doubt even a small number of people could survive this for long!

      --
      Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
  5. Nobel prize for pulsar discovery by etymxris · · Score: 5, Interesting

    Anybody know why Jocelyn Bell received no credit for actually discovering pulsars, yet her thesis advisor, who actually seemed to do nothing, did?

    1. Re:Nobel prize for pulsar discovery by Scott+Ransom · · Score: 2, Interesting

      Actually, this is not the case. Hewish received the Nobel prize _precisely_ because he and Jocelyn Bell discovered pulsars -- one of the greatest discovies in 20th century astronomy.

      And while Jocelyn has always been very gracious (and modest) when discissing this topic, the majority of astronomers believe that an injustice was done by the Nobel committee. It was precisely because of this injustice, in fact, that when The Nobel was awarded to Joe Taylor for work on the Binary Pulsar (for showing that the orbital period of the system was decaying as predicted due to gravitational radiation), that they also awarded it to Russell Hulse. Russell had effectively left astronomy by then and had done very little of the follow-up work which showed the workings of GR. Yet it was he that had discovered the system and determined many of its properties.

      Note: I am a pulsar astronomer and have first-hand knowledge of this.

    2. Re:Nobel prize for pulsar discovery by spanklin · · Score: 2, Interesting

      Jocelyn has also won her fair share of other (not as prestigious) prizes. Almost ten years ago, she gave the "Jansky lecture" awarded annually by the National Radio Astronomy Observatory to someone who has made outstanding contributions to the advancement of astronomy. I agree with Scott -- the majority of astronomers that I talked to before her talk told us that she had been unfairly treated by the Nobel committee. I think that the astronomical community has done their best to try and right this wrong. As an aside, most of the Jansky lectures that I attended were awful. Jocelyn's was the first that I saw, and hers was outstanding.

  6. Whoops by etymxris · · Score: 2, Interesting

    It seems that Hewish and Ryle got the Nobel for their role in radio astronomy, not pulsars.

  7. Indirect detection by Beryllium+Sphere(tm) · · Score: 4, Interesting

    If the system is emitting gravity waves then it's losing energy by doing so, and the orbit will gradually decay.

    You can measure the orbit precisely when there's a pulsar in the system, which is a good timing source. Then you can check whether the orbit's decaying at the rate predicted by the math of gravity wave radiation.

    That measurement's been done for another binary system. See http://astrosun2.astro.cornell.edu/academics/cours es//astro201/psr1913.htm and read about 3/4 of the way down.

    Observation agrees with Einstein in this case.

  8. Maybe Not. by Anonymous Coward · · Score: 5, Interesting

    Article 1, Article 2.

    Some scientists that have inspected the calculations believe the experiment is flawed and that they instead measured the speed of light itself (ie: they probably measured the speed of the light they were using to make their observations with, not the speed of the Jupiter distortion).

    Correct answer: The speed of gravity is not (yet) a scientifically proved and universally accepted fact. Saying anything else is bad science.

  9. Not first by Anonymous Coward · · Score: 1, Interesting

    The first binary pulsar discovered was PSR1913+16, by Hulse and Taylor. They won the Nobel in 1993. Their measurements of the decay of the binary orbit fitted with GR's prediction of energy loss due to gravitational wave emmission, which caused great excitement. 20-30 years ago.

    Finding another binary pulsar (I dont even think this is the second) is interesting, as measurements can be made and more curve fitting and happiness can result, and perhaps a better estimate of how many of these double systems exist can be made. But its not like we can point LIGO to it, or expect it to help our search for gravitational waves in any way.

    The reporting in this article is pretty bad

    Yes IAAP

  10. tells you less than you might think by ajagci · · Score: 2, Interesting

    The news has been welcomed by gravitational wave hunters, since it boosts their hopes for detecting the gravitational waves [...] General relativity predicts that the two stars will slowly wobble like spinning tops allowing new tests of the theory.

    Alternative theories to general relativity usually also predict such effects, including gravitational waves. So, these results, even if confirmed, don't actually tell you a whole lot. What they do tell you is that Newtonian mechanics isn't quite right, but, then, we already knew that.

  11. In 85 million years, "wioll haven be" by NoData · · Score: 3, Interesting

    In the university press release:
    The stars will coalesce in only approximately 85 million years, sending a ripple of gravity waves across the Universe

    So...wait, 85 million years from when? Now? Or is it 85 million years from what we currently observe, which is probably several million years in the past (neither link provides the distance of the pulsars from earth)?
    In other words, will we observe the coalescing in 85 million years, or 85 million + time of transit?

    Sheesh, it never occurred to me how dicey verb tense is in astronomy...Talking about the future of distant objects that exist in the past which we are observing presently.. Reminds me of Dr. Streetmentioner's Time Traveler's Handbook of 1001 Tense Formations from Restaurant at the End of the Universe.

  12. Animations by allrong · · Score: 3, Interesting

    Animations of the evolution and current state of the pulsar system are available.

    --
    What is the inverse of the Matrix?
  13. Re:gravity wave detection by Anonymous Coward · · Score: 1, Interesting

    You're talking about gravity waves, but the article is talking about gravitational waves. They're quite different. Gravity waves have nothing to do with the propagation speed of the gravitational field; they're waves in matter driven by the Earth's gravity. True gravitational waves are far more difficult to detect.

  14. Gravity Waves? Bah. Humbug. by Ralph+Spoilsport · · Score: 2, Interesting
    Prediction:

    They will never discover Gravity Waves because Gravity is not a force. It is an illusion of geometry caused by mass moving in space. It's kind of like an optical illusion - it looks like gravity exists, but it really doesn't. It's just how objects move through space/time.

    Next?

    HW

    the glass isn't half full or empty - it's just too big.

    --
    Shoes for Industry. Shoes for the Dead.
  15. Re:Metaphysics is exciting... by Anonymous Coward · · Score: 1, Interesting

    Not a bad question. I am a physics undergrad, so I haven't taken any GR, but I think that we can draw an analogy here between Gravity and Electromagnetism, with masses being like charges. A charge sitting still emits an electric field that is not wavelike in this kind of sense. Fields fall off as 1/r^2 and nearby charges just add their fields together classicaly. Accelerating charges emmit EM waves, which can interfere and create points of total destructive interference where there is no net field.

    Gravity is much the same, in that still masses have fields that fall off as 1/r^2, but accelerating masses emmit gravitational waves (or is it gravity waves? I always forget which is which) which could might be able to interfere much like EM waves, creating nodes that have no net oscillation, but still whatever the local field is without the waves. I don't really know, but I suspect the same kind of behavior.