tag:blogger.com,1999:blog-28837843.post3233448902765339930..comments2024-03-19T07:10:27.303-07:00Comments on Quark Soup by David Appell: Who Will Win the Nobel Prize for Gravitational Waves?David Appellhttp://www.blogger.com/profile/03318269033139447591noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-28837843.post-14455516162037432952016-02-18T23:21:14.298-08:002016-02-18T23:21:14.298-08:00Layzej,
I don't agree with Greg Laden, becaus...Layzej,<br /><br />I don't agree with Greg Laden, because the previous versions of LIGO were simply incapable of detecting gravitational waves of the sort that were expected. They were really 10+ years of enhancing a basic machine and getting all its parts to work together.<br /><br />It may be a little surprising that advanced LIGO found a GW so quickly. Or it may be that there are lots of sources out there that the previous versions of LIGO just could never see. I'm sure lots of people are looking at the odds that this particular wave was detected, and what it means for the number of detectable events out there -- whether they are more like a few per year, or more like dozens per year, or hundreds. No one really knows.<br /><br />I wouldn't be at all surprised if LIGO is now busily analyzing other signals they saw.<br /><br />Several years ago, before I know anything about LIGO, I wrote and asked one of their project managers if the fact that enhanced LIGO (the machine as of several years ago) hadn't detected any GWs, if that meant they didn't exist. He said, absolutely not, that they really didn't expect to detect anything (any detection would have been a big surprise), and that everyone was waiting for Advanced LIGO. They had a lot of expectations about where the signals were and weren't.<br /><br />The detected signal was a pretty close match to theoretical expectations. That's a stronger result than just measuring a time to determine the speed of neutrinos. And I'd bet that neutrino team really regrets letting that all get away from them and their speculating, under pressure, about what their measurement might mean. They really had a lot of verification to do before they should have announced, and they didn't do it. They got caught up in the moment. <br /><br />By contrast, LIGO looked at their signal for about 5 months before announcing. <br /><br />David Appellhttps://www.blogger.com/profile/03318269033139447591noreply@blogger.comtag:blogger.com,1999:blog-28837843.post-33105352620840408182016-02-18T23:08:32.441-08:002016-02-18T23:08:32.441-08:00Cesar: Yes, I thought about Rainer Weiss after I w...Cesar: Yes, I thought about Rainer Weiss after I wrote this. You're probably right. But I think it'd be a shame if the LIGO project team didn't get at least a piece of the Prize. David Appellhttps://www.blogger.com/profile/03318269033139447591noreply@blogger.comtag:blogger.com,1999:blog-28837843.post-63874515874325886932016-02-18T23:04:45.670-08:002016-02-18T23:04:45.670-08:00PS: I also wrote a feature article about numerical...PS: I also wrote a feature article about numerical general relativity, awhile back:<br /><br />"Relativity's New Revolution," Physics World, October 2011.<br />http://www.davidappell.com/articles/PWOct11appell-numerical_relativity.pdf<br /><br />It has very nice figures, if nothing else.David Appellhttps://www.blogger.com/profile/03318269033139447591noreply@blogger.comtag:blogger.com,1999:blog-28837843.post-58685717024869795212016-02-18T23:03:05.835-08:002016-02-18T23:03:05.835-08:00Joe, I'm sorry I didn't get to your questi...Joe, I'm sorry I didn't get to your question sooner.<br /><br />Yes, the gravitaional waves detected from LIGO were from a black hole coalescence. Each hole was about 30 solar masses, plus or minus (not exactly; that's off the top of my head). <br /><br />It was just one event. In fact, detectable gravitational waves (at LIGO) only come from the last second of the coalescence, when the gravitational field is very strong and changing fast. IIRC, the grav wave detected by LIGO was only about 10 milliseconds in duration. That will be typical of anything else LIGO detects, according to numerical calculations done via general relativity.<br /><br />Equally satisfying is that these detailed calculations predicted the wave seen. This is the first time "strong field" calculations of Einstein's equations have been verified. All other examples -- the deflection of starlight, the change in the perihelion of mercury, gravitational redshift, etc -- were done only as first-order perturbations to Newton's law of gravity. <br /><br />So it's quite amazing that Einstein's theory passed this strong-field test.<br /><br />David Appellhttps://www.blogger.com/profile/03318269033139447591noreply@blogger.comtag:blogger.com,1999:blog-28837843.post-47361467772743672622016-02-12T07:17:41.562-08:002016-02-12T07:17:41.562-08:00Greg Laden brings up an interesting point: "...Greg Laden brings up an interesting point: "I don’t like the fact that the device was turned off and upgraded, then, very soon after being turned on, found a gravitational wave, and apparently hasn’t found another since then. I’m worried that this is similar to when CERN detected faster than light neutrinos. Everybody knew there were no faster than light neutrinos, but the instruments detected them anyway. Eventually, it was discovered that something was going on with the way the instruments were wired up that made the detector wrong." - http://scienceblogs.com/gregladen/2016/02/11/about-those-gravitational-waves-they-just-discovered/<br /><br />We know there should be no faster than light particles, so there would have been a great effort to find an alternate explanation. It sounds like the LIGO folks were extremely cautious, but I wonder if the fact that we know gravitational waves should exist would have some impact on the level of scrutiny.Layzejhttps://www.blogger.com/profile/11346550512734519728noreply@blogger.comtag:blogger.com,1999:blog-28837843.post-5701855747205870082016-02-11T12:18:51.513-08:002016-02-11T12:18:51.513-08:00What about Rainer Weiss who conceived of LIGO and ...What about Rainer Weiss who conceived of LIGO and had to talk Kip into it? :)Cesarhttps://www.blogger.com/profile/03119583900742134329noreply@blogger.comtag:blogger.com,1999:blog-28837843.post-3109753230201412622016-02-11T09:26:22.625-08:002016-02-11T09:26:22.625-08:00If the Higgs Boson garnered a Nobel Prize, then I ...If the Higgs Boson garnered a Nobel Prize, then I do not see why this should not.Unknownhttps://www.blogger.com/profile/08658697422961922139noreply@blogger.comtag:blogger.com,1999:blog-28837843.post-74602013217761220982016-02-11T07:57:27.241-08:002016-02-11T07:57:27.241-08:00David, I just read your excellent article in Physi...David, I just read your excellent article in Physics World. Very clearly written, by the way. Do you know if in fact the gravitational wave discovered was a binary black hole coalescence? Was it just one event or a series of events. Thanks!JoeThttps://www.blogger.com/profile/06540568535579405609noreply@blogger.com