Astrophysicists unveil glut of gravitational-wave detections • Hacker News Board

Re: Astrophysicists unveil glut of gravitational-wave detections

#11

Post by TheOtherHobbes » Wed, Nov 10, 2021, 3:58 PM UTC

wpietri wrote: post #9

jaspax wrote: post #4

Earlier quoted context omitted.

Why would you have FOMO? Why is any particular gravitational wave important enough that you'd worry about missing it? I'm not trying to hassle you here, I'm genuinely perplexed by this attitude.

I used to work in a library and we all had a similar feeling about books. They were all valuable and to be preserved! Objectively, that's not practical. But that base irrational feeling is still useful and important.

Technically we've missed at least four billion years of gravitational wave events, so a week of shutdown for an upgrade isn't going to make a huge difference to that.

Re: Astrophysicists unveil glut of gravitational-wave detections

#12

Post by nharada » Wed, Nov 10, 2021, 4:07 PM UTC

LIGO blows my mind whenever I hear news about it. The sensitivity alone is insane -- it can detect a change in distance between its mirrors 1/10000th the width of a proton. This is the equivalent of measuring the distance to the nearest star (4.2 light years) to an accuracy of 1 human hair. Those are bonkers numbers. How the hell did we even come up with this thing?

Re: Astrophysicists unveil glut of gravitational-wave detections

#13

Post by raymondh » Wed, Nov 10, 2021, 4:13 PM UTC

Invictus0 wrote: post #2

Interesting how, even with three LIGO observatories, there is still a 15% false positive rate. How many more observatories are needed to reduce this to a negligible number?

GW fanboy here. IIRC, additional detectors provide better ability to locate the GW source so that other telescopes can also capture an event. They also improve polarization measurements. The number of detectors doesn't determine the false positive rate which is just a user selected point on a receiver operating characteristic curve. In general, we get more pay off from improving detect sensitivity than from having more detectors (that's why GEO 600 was more useful for the tech it developed rather than its most recent observations).

Re: Astrophysicists unveil glut of gravitational-wave detections

#14

Post by omegalulw » Wed, Nov 10, 2021, 4:17 PM UTC

netcraft wrote: post #3

the Gravitational Observatories are so impressive to me - I can remember reading about them being theoretical well before LIGO ever started construction, and the fact that theyre here and working just like we expected is so amazing. I can't wait until we have LISA in space! But its so strange when we shut it off to do upgrades and stuff - like I totally understand why we have to do it, but its like we finally turned…

> the thought that there are events that are going on right now that we will never be able to detect because we arent listening gives me major FOMO.

I can relate to the sentiment but keep in mind that human timescales are downright puny compared to cosmological timescales. And there's lots of stuff going on all the time (lots is an understatement) so I would say you won't lose much turning off the detector for a year.

Re: Astrophysicists unveil glut of gravitational-wave detections

#15

Post by im3w1l » Wed, Nov 10, 2021, 4:17 PM UTC

pinko wrote: post #10

gus_massa wrote: post #6

Earlier quoted context omitted.

Do you publish some number about how sure you are?

Yes, we carefully explain the statistical confidence of our detections in each discovery paper, and there are dozens of methods papers that go into excruciating detail on those techniques. Prior to our first detection, the overwhelming prime directive of our collaboration was _not to make a false detection_ and we went to insane lengths to avoid one; e.g., we had a small team of people secretly injecting false signal…

That sounds hilarious, but you must be quite unique in having this approach right? Or are the particule physics people playing similar games?

Re: Astrophysicists unveil glut of gravitational-wave detections

#16

Post by pinko » Wed, Nov 10, 2021, 4:29 PM UTC

im3w1l wrote: post #15

pinko wrote: post #10

Earlier quoted context omitted.

Yes, we carefully explain the statistical confidence of our detections in each discovery paper, and there are dozens of methods papers that go into excruciating detail on those techniques. Prior to our first detection, the overwhelming prime directive of our collaboration was _not to make a false detection_ and we went to insane lengths to avoid one; e.g., we had a small team of people secretly injecting false signal…

That sounds hilarious, but you must be quite unique in having this approach right? Or are the particule physics people playing similar games?

Unique as far as I know, at least in a scientific collaboration like ours. But we were unusually sensitive to the risk of false detections given (a) skepticism of LIGO's prospects from other physicists, and (b) the lingering stain of a false detection claim, from a bar detector, a few decades earlier.

We believed that if we had announced a discovery that turned out to be wrong, it would probably have meant the end of our experiment, and in practice the end of the field, at least for a long time. It was fortuitous that the first detection turned out to be gold plated and unambiguous, otherwise we would have probably published a bunch of "we saw something interesting but can't claim it as a GW discovery" papers on the next few weaker events before we would have felt comfortable making a confident claim.

Re: Astrophysicists unveil glut of gravitational-wave detections

#17

Post by matt123456789 » Wed, Nov 10, 2021, 4:32 PM UTC

pinko wrote: post #10

gus_massa wrote: post #6

Earlier quoted context omitted.

Do you publish some number about how sure you are?

Yes, we carefully explain the statistical confidence of our detections in each discovery paper, and there are dozens of methods papers that go into excruciating detail on those techniques. Prior to our first detection, the overwhelming prime directive of our collaboration was _not to make a false detection_ and we went to insane lengths to avoid one; e.g., we had a small team of people secretly injecting false signal…

Are your security cameras sensitive enough to pick up rogue sophons as well? (Three body reference, sorry.)

Re: Astrophysicists unveil glut of gravitational-wave detections

#18

Post by ww520 » Wed, Nov 10, 2021, 4:36 PM UTC

LIGO is a huge milestone. Turning it on is like the moment Galileo pointed his telescope to the moon. This is a new class of instruments observing the universe in a medium that was never utilized before. Using gravitational waves can observe things that cannot be seen before, like stars behind the dust clouds.

It opens a new window to the world. We might finally be able to “see” dark matter. May be able to see the gravitational imprint from before the Big Bang, the gravitational leak from extra dimension or other universes.

Re: Astrophysicists unveil glut of gravitational-wave detections

#19

Post by mrfusion » Wed, Nov 10, 2021, 4:39 PM UTC

Could we be seeing warp drive signatures?

Re: Astrophysicists unveil glut of gravitational-wave detections

#20

Post by mabbo » Wed, Nov 10, 2021, 4:40 PM UTC

The article mentions the new KAGRA detector in Japan joining the group. Does anyone know: how does the accuracy improve as more detectors come online?

Will we see a day where we have 20, 50, 100 detectors around the globe and events are near-certain because so many detectors see them? Or is the diminishing returns, and 4 detectors is already too many?