The Laser Interferometer Gravitational-Wave Observatory (LIGO) is one of the most amazing instruments ever built. It was constructed (and is now being upgraded) to search for gravitational waves. I’ll wax poetic about it soon enough. In the interim, readers can whet their appetites with Einstein’s cosmic messengers, a collaboration between Andrea Centazzo (a multimedia artist) and Michele Vallisneri (a physicist at the Jet Propulsion Laboratory). They will be performing a world premiere of their work on the Caltech campus tomorrow evening (Oct. 30); the event is free, and open to the public. The concert will be preceded by public talks by Kip Thorne and Jay Marx, two of the most knowledgeable people alive when it comes to gravitational-wave theory and observation. The evening promises to be an interesting melding of science and art. Centazzo will perform the music live, synchronized with the video. The concert attempts to capture the grandeur of LIGO, as well as shed light (and sound) on the nature of gravitational waves. For those of us poor souls unfortunate enough not to live near Pasadena, we will have to satisfy ourselves with video:
For those of you that are able to make it to the concert, please let us know your thoughts on the event!
October 29th, 2008 at 5:44 pm
I’m interested in your thoughts about the significance of LIGO results to date: from what I can understand from a quick skim of the papers listed, no GW have been seen at all. Does this suggest merely a sensitivity issue, or some bigger gap in our understanding of GWs.
October 29th, 2008 at 6:23 pm
Horse, you’re quite right in that so far no convincing evidence for a directly observed gravitational wave has yet been seen, but it’s almost certainly just a sensitivity issue at the moment. I’d say (and I have to admit some bias in that my job is gravitational wave detection) that the existence of gravitational waves is well over a 99% certainty – their inferred presence has already won a Nobel Prize for Hulse and Taylor and GR has matched predictions with subsequent observations at every occasion. Data from the last LIGO science run was at it’s design sensitivity, which gave it a reach of about 15 Mpc for binary neutron star mergers (one of the strongest expected type of signal), but the (rather uncertain) theoretical rate of these events suggest that at this range we’d expect only about 1 per 100 years. The detectors are currently being upgraded to about twice there previous sensitivity for another data taking run next year, which will increase their range by a factor of two, but the volume of space that they cover by about 8 times and give a corresponding increase in event rate (in fact the event rate gets larger due to the more homogeneous distribution of galaxies once you get past the rather sparse local 10 Mpc). By about 2014 we should have the next generation advanced detectors with 10 times better sensitivity than present, corresponding to a 1000 increase in observed volume at which time we should be seeing at least several events per year from binary neutron stars, plus hopefully many other local sources – if we don’t see anything in the advanced detector era (or with the space-based detector LISA due to be launched a few years later) then some rethinks in our understanding might be in order, but not until then.
October 29th, 2008 at 7:40 pm
That is a fair account. The Einstein field equations predict gravity waves with quadrupole and higher moments in a way analogous to how Maxwell’s equations predict EM waves. Of course a theoretical “should” can never take the place of an experimental “does.” The Hulse-Taylor measurement of pulsar orbits does illustrate that orbital energy is going away at a rate predicted by general relativity. This is a good signpost, but it does not clinch the case for gravity waves.
If over time we can’t detect gravity waves with ever more sensitive detectors then a whole lot of physics work done over decades is in danger of collapse.
Lawrence B. Crowell
October 31st, 2008 at 3:21 am
This would be better set to the music of Stars of the Lid.