4 ms·

Rumours swirl over credibility of big bang ripple find

40 points by hachiya 12y ago

Udo 12y ago
At first I was skeptical about the article (this being NewScientist), but it seems that BICEP's findings might indeed be in doubt. This would be exciting, since it moves our search for gravity waves back to square zero. People have tried for quite some time to measure them and so far no experiment has succeeded. On the other hand that's not surprising for such an elusive phenomenon, so the jury is still out.
- prawks 12y ago
  I always find it awesome that setbacks in science are considered "exciting" and not "disappointing". I think it speaks volumes about our pursuit of scientific knowledge.
  - zenojevski 12y ago
    Knowing "what isn't" is often more valuable than knowing "what is", when there are so many options. It can strike out an entire tree of dependent conditions, enabling pursuers to focus better, with more energy and insight than before.
- cshimmin 12y ago
  As a physicist, I am still skeptical. And it's not just NewScientist, AAAS's (supposedly reputable) online magazine broke the same story a day earlier [1]. There is literally no news content in this story. The story is "some guy says they did it wrong, BICEP says they did it right". It is not news that they used preliminary conference slides to subtract foregrounds, they have been open about that from the get-go. People are axious about the result, as it certainly will change when Planck drops their full dataset in October. It's likely that their measured value of r=0.20 will be lowered (although actually that can be cosmologically preferable). But I don't much expect that the difference will be large enough to invalidate their r=0 exclusion, which is the really ground-breaking result. And by the way, scientists are human; they make mistakes. If that happens, then you can expect BICEP2 to retract their results. But until the _BICEP2_ team (not some guy who wan't involved with the analysis) makes a statement that they did something wrong, there's simply no news here. [1] http://news.sciencemag.org/physics/2014/05/blockbuster-big-bang-result-may-fizzle-rumor-suggests http://news.sciencemag.org/physics/2014/05/blockbuster-big-b...
  - Luc 12y ago
    Sure, but it's mainly physicists I've heard gossip about it. As you say, scientists are human, and gossiping is fun...
  - mturmon 12y ago
    Good points. It was news to me, though, to read that there is an asterisk of uncertainty about the BICEP2 result, because the original flurry of press lost that asterisk. ("5 sigma"!). I happened to be talking with someone from the Planck team yesterday, and they mentioned the seriousness of these reservations. He was not pre-judging one way or the other, just saying it's not obvious at present how it's going to shake out.
- mrfusion 12y ago
  What would it mean if gravity waves are never found, even by equiptment we are sure should be finding them? Are there any theories of gravity that don't include gravity waves?
  - Udo 12y ago
    > What would it mean if gravity waves are never found, even by equiptment we are sure should be finding them? We are currently far, far away from that point. We're just at the beginning of a long, statistics-driven process. If gravitational waves remain elusive, that would mean there is something profoundly wrong with the way we understand relativity. To be fair, there is arguably a lot about gravity which we don't yet understand - but gravitational waves are pretty much a required feature in many respects. For example, without them our understanding of the orbital mechanics of massive objects would have to be revised. It would mean that massive bodies orbiting each other do not lose energy due to gravitational radiation. > Are there any theories of gravity that don't include gravity waves? Not any credible ones that I know of, maybe someone else can present one?
    - mrfusion 12y ago
      Would it also mean that changes from gravitational sources would affect other bodies instantaneously? Or have we already proven experimentally that's not the case? I guess I'm saying, if gravity waves conclusively didn't exist, how would information about gravity travel?
  - has2k1 12y ago
    Without gravitational waves the statement the "fabric of space" becomes mysterious. What "fabric" if it does not fold in ways we expect it to be folding based on other observations.
  - ISL 12y ago
    If gravity waves, in general, are not found, then there's a spectacular conflict between General Relativity and the Hulse-Taylor pulsar system [1]. A direct detection with earth-based detectors from a nearby inspiral is quite likely within the next decade; thousands of scientists have bet their careers on it [2]. If early-universe gravitational waves aren't found, then some major theories of inflation and cosmology will require adaptation. In the grand scheme of things, this is still a big deal, but less-so than shattering a core prediction of GR. [1] http://en.wikipedia.org/wiki/PSR_B1913+16 http://en.wikipedia.org/wiki/PSR_B1913+16 [2] https://www.advancedligo.mit.edu/ https://www.advancedligo.mit.edu/
has2k1 12y ago
Well, I feel for the scientists involved. Before that revelation my expectations where that gravitational waves would be detected after the next supernova in the milky-way galaxy. That would require a lot less ingenuity. I would take discovery by any method during my lifetime, in fact the less expected the better.
- ISL 12y ago
  Look to the Hulse-Taylor binary pulsar; perhaps you needn't wait any longer: http://en.wikipedia.org/wiki/PSR_B1913+16 http://en.wikipedia.org/wiki/PSR_B1913+16 The energy loss rate from it and similar systems is in agreement with the gravitational wave predictions of General Relativity at the ~0.3% level or so. The detection method by which BICEP has made its claim is somewhat indirect, too, as they see very weak distortions of CMB polarization made by the aftereffects of said waves. Direct detection on earth is likely to come from a neutron-star binary merger. If we're lucky enough to get a local supernova in our lifetimes, it will be a huge deal for gravitational waves and many other branches of physics and cosmology. Our observational powers have increased by orders of magnitude since 1987A.
galvanist 12y ago
See also the National Geographic coverage: http://news.nationalgeographic.com/news/2014/05/140514-bicep2-physics-rumors-science-big-bang/ http://news.nationalgeographic.com/news/2014/05/140514-bicep...

40 points by hachiya 12y ago

Udo 12y ago

At first I was skeptical about the article (this being NewScientist), but it seems that BICEP's findings might indeed be in doubt. This would be exciting, since it moves our search for gravity waves back to square zero. People have tried for quite some time to measure them and so far no experiment has succeeded. On the other hand that's not surprising for such an elusive phenomenon, so the jury is still out.

prawks 12y ago
I always find it awesome that setbacks in science are considered "exciting" and not "disappointing". I think it speaks volumes about our pursuit of scientific knowledge.
- zenojevski 12y ago
  Knowing "what isn't" is often more valuable than knowing "what is", when there are so many options. It can strike out an entire tree of dependent conditions, enabling pursuers to focus better, with more energy and insight than before.
cshimmin 12y ago
As a physicist, I am still skeptical. And it's not just NewScientist, AAAS's (supposedly reputable) online magazine broke the same story a day earlier [1]. There is literally no news content in this story. The story is "some guy says they did it wrong, BICEP says they did it right". It is not news that they used preliminary conference slides to subtract foregrounds, they have been open about that from the get-go. People are axious about the result, as it certainly will change when Planck drops their full dataset in October. It's likely that their measured value of r=0.20 will be lowered (although actually that can be cosmologically preferable). But I don't much expect that the difference will be large enough to invalidate their r=0 exclusion, which is the really ground-breaking result. And by the way, scientists are human; they make mistakes. If that happens, then you can expect BICEP2 to retract their results. But until the _BICEP2_ team (not some guy who wan't involved with the analysis) makes a statement that they did something wrong, there's simply no news here. [1] http://news.sciencemag.org/physics/2014/05/blockbuster-big-bang-result-may-fizzle-rumor-suggests http://news.sciencemag.org/physics/2014/05/blockbuster-big-b...
- Luc 12y ago
  Sure, but it's mainly physicists I've heard gossip about it. As you say, scientists are human, and gossiping is fun...
- mturmon 12y ago
  Good points. It was news to me, though, to read that there is an asterisk of uncertainty about the BICEP2 result, because the original flurry of press lost that asterisk. ("5 sigma"!). I happened to be talking with someone from the Planck team yesterday, and they mentioned the seriousness of these reservations. He was not pre-judging one way or the other, just saying it's not obvious at present how it's going to shake out.
mrfusion 12y ago
What would it mean if gravity waves are never found, even by equiptment we are sure should be finding them? Are there any theories of gravity that don't include gravity waves?
- Udo 12y ago
  > What would it mean if gravity waves are never found, even by equiptment we are sure should be finding them? We are currently far, far away from that point. We're just at the beginning of a long, statistics-driven process. If gravitational waves remain elusive, that would mean there is something profoundly wrong with the way we understand relativity. To be fair, there is arguably a lot about gravity which we don't yet understand - but gravitational waves are pretty much a required feature in many respects. For example, without them our understanding of the orbital mechanics of massive objects would have to be revised. It would mean that massive bodies orbiting each other do not lose energy due to gravitational radiation. > Are there any theories of gravity that don't include gravity waves? Not any credible ones that I know of, maybe someone else can present one?
  - mrfusion 12y ago
    Would it also mean that changes from gravitational sources would affect other bodies instantaneously? Or have we already proven experimentally that's not the case? I guess I'm saying, if gravity waves conclusively didn't exist, how would information about gravity travel?
- has2k1 12y ago
  Without gravitational waves the statement the "fabric of space" becomes mysterious. What "fabric" if it does not fold in ways we expect it to be folding based on other observations.
- ISL 12y ago
  If gravity waves, in general, are not found, then there's a spectacular conflict between General Relativity and the Hulse-Taylor pulsar system [1]. A direct detection with earth-based detectors from a nearby inspiral is quite likely within the next decade; thousands of scientists have bet their careers on it [2]. If early-universe gravitational waves aren't found, then some major theories of inflation and cosmology will require adaptation. In the grand scheme of things, this is still a big deal, but less-so than shattering a core prediction of GR. [1] http://en.wikipedia.org/wiki/PSR_B1913+16 http://en.wikipedia.org/wiki/PSR_B1913+16 [2] https://www.advancedligo.mit.edu/ https://www.advancedligo.mit.edu/

has2k1 12y ago

Well, I feel for the scientists involved. Before that revelation my expectations where that gravitational waves would be detected after the next supernova in the milky-way galaxy. That would require a lot less ingenuity. I would take discovery by any method during my lifetime, in fact the less expected the better.

ISL 12y ago
Look to the Hulse-Taylor binary pulsar; perhaps you needn't wait any longer: http://en.wikipedia.org/wiki/PSR_B1913+16 http://en.wikipedia.org/wiki/PSR_B1913+16 The energy loss rate from it and similar systems is in agreement with the gravitational wave predictions of General Relativity at the ~0.3% level or so. The detection method by which BICEP has made its claim is somewhat indirect, too, as they see very weak distortions of CMB polarization made by the aftereffects of said waves. Direct detection on earth is likely to come from a neutron-star binary merger. If we're lucky enough to get a local supernova in our lifetimes, it will be a huge deal for gravitational waves and many other branches of physics and cosmology. Our observational powers have increased by orders of magnitude since 1987A.

galvanist 12y ago

See also the National Geographic coverage: http://news.nationalgeographic.com/news/2014/05/140514-bicep2-physics-rumors-science-big-bang/ http://news.nationalgeographic.com/news/2014/05/140514-bicep...