A major upgrade of the LIGO gravitational-wave detector is almost complete | Hacker News Reader

A major upgrade of the LIGO gravitational-wave detector is almost complete

nature.com

52 pointsalphanumeric015 comments

For clarity, as I'm close to LIGO (but not in the collaboration) and found the title misleading:

A major upgrade of LIGO is almost complete. When it comes back online, if the detectors reach design sensitivity, it's sufficient to make detection of gravitational waves from neutron-star inspirals probable. As both LIGO and Virgo are down for upgrades, there's no chance of a major new detection from either until they're re-commissioned and running well (timescale of ~year+).

As reported at a workshop at the Institute for Nuclear Theory here at the University of Washington a few weeks ago, the Advanced LIGO upgrades have been going quite well; the riskiest work is coming toward a close.

The linked article makes no claims that there's anything new being dredged out of past science runs on initial/enhanced LIGO (which remains possible, if unlikely).

Thanks! If you can suggest a better title, we'll use it. In the meantime, we changed it to a sentence from your comment.

Sounds great -- I'm hesitant to wordsmith further. The previous title was correct, too, it just led me to the wrong first impression. aLIGO is "on the verge of detection", on timescales of years. For a project begun in 1992 or earlier, that's real soon. Everyone in the experimental detection community is excited and upbeat.

For the skeptic sibling comment -- there remains a non-negligible chance that aLIGO will see nothing. If it reaches its design specifications and sees nothing, it would force mainstream astrophysics to rethink a lot of widely-held beliefs regarding neutron star abundances and merger rates.

>> For the skeptic sibling comment -- there remains a non-negligible chance that aLIGO will see nothing. If it reaches its design specifications and sees nothing, it would force mainstream astrophysics to rethink a lot of widely-held beliefs regarding neutron star abundances and merger rates.

Thanks. I'm not so much a critic of LIGO, I just like science writing that doesn't obscure the facts (as a sober scientist would assess them). It's odd in any case to assert that a scientific instrument is on the verge of a history-making observation (that implies being able to see the future). A person with a genuine interest in scientific progress ought to be able to handle the truth: the inescapable lesson that LIGO and other projects have taught us so far is that gravity waves are difficult to detect by all known methods. Science is about accepting truth as we are able to observe it.

For the impatient, the truth:

"When it comes back online, if the detectors reach design sensitivity, it's sufficient to make detection of gravitational waves from neutron-star inspirals probable. As both LIGO and Virgo are down for upgrades, there's no chance of a major new detection from either until they're re-commissioned and running well (timescale of ~year+)."

Verdict on claim in title: "possible, if unlikely."

Thanks for the dose of truth.

Reply from myself: the title has been changed, so it no longer makes that claim.

I actually got a chance to tour the LIGO facility in Louisiana recently. They have an open house "Science Saturday" that, while somewhat kid oriented, is pretty well put together. The control room was particularly fun to look around in and I'd recommend a visit if in the area.

Hanford (Washington state) tours: http://www.ligo-wa.caltech.edu/informal.html

Livingston (Louisiana) tours: http://www.ligo-la.caltech.edu/SEC.html

I went there in college (went for the physics, stayed for the fun science room) - what I remember most was an exceptionally well-built Chladni plate that you could control.

Whoa; hadn't heard of a Chladni plate before.

Here's a video: http://www.youtube.com/watch?v=lRFysSAxWxI

Can't find one of anything at Livingston or Hanford, though.

At Hanford, they have one of Weber's original bar detectors in the visitor's center lobby... So cool.

http://www.ligo.caltech.edu/LIGO_web/0312news/0312one.html

There was a huge thread on this a while back when bicepkeck made some measurements.

https://news.ycombinator.com/item?id=7416694 (see parent)

I've been fascinated by ligo ever since learning about it.

Interferometers seem to me strange but wonderful instruments that seem simple yet I think get at very fundamental properties.

There was a while where interferometry was the "next big thing*, but it's proven to be considerably more difficult in practice than in theory. But perhaps with time we'll see it reach some significant fraction of its potential, which is enormous.

I'm afraid that I don't follow what you mean by interferometry being the next big thing. I was pretty well under the impression that it was the PREVIOUS big thing. For example, when I was in undergrad, the oldest professor in the department had done interferometry during his PhD thesis. His adviser, who died before the moon landing, had done interferometry during his thesis.

Hell, I built an interferometer during my thesis. I tell myself that it's not old hat because I was doing it with neutrons instead of photons and we had a clever way of getting huge fluxes without drowning out our signal, but it's also something that you can explain to a grad student in half an hour. Or an to undergrad in ten minutes.

Anyway, I'm sure that I'm missing something here. In what area had you heard that interferometry might be the next big thing?

There are different types of interferometry and different "waves" of interferometry development.

The first wave started around the mid 19th century and saw the advent of lots of new instrumentation that revolutionized science. Speed of light measurements. The Michelson-Morley interferometry test which laid the foundation for Relativity. Later FT-IR instrumentation. Fabry-Perot imaging. Etc.

The second(?) wave happened in the late 20th/early 21st century and surrounded visible light imaging, synthetic aperture interferometric telescope systems. Most major large telescope installations built since the 1990s have incorporated interferometric plans into them. The Keck 1 & 2 telescopes, for example, and the Very Large Telescope array. Both were built with the idea that interferometry systems would enable observations with "virtual" telescopes having diameters on the order of 100m. However, that hasn't worked out to be nearly as useful nor as practical as was imagined. The Keck Interferometer has been mothballed due to lack of interest/funding and the VLTI has been rarely used and has struggled to remain relevant. In fact, it's been found that large telescopes aren't particularly advantageous for interferometric unit telescopes.

Add to that the saga of space based interferometeric observatories, which have so far come to naught. There was the long-planned, long-revised space interferometry mission which was finally cancelled some years back. Then there were several varieties of telescopic interferometer arrays or formation flying fleets tasked mostly with detecting and observing distant planets (such as NASA's "terrestrial planet finder" concept and ESA's "Darwin" concept along similar lines). The idea of those was to use interferometry to both create very high resolution imaging and also to deeply "null" the starlight of parent stars. Over the last decade or two the limitations and difficulties of interferometry have become more apparent and the competitive advantage of alternate methods (such as large ground based telescopes using ordinary coronographs coupled with adaptive optics and space-based telescopes using coronographs) has more or less erased the promised future of interferometric telescope arrays as a new major class of instrumentation that would open up huge new realms of observation.

LEGO has come along a lot since I last played with it.

Reply on news.ycombinator.com