Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Astrophysicists unveil glut of gravitational-wave detections

nature.com

Post reply on HN
Print view View original

31–40 of 108 posts

Re: Astrophysicists unveil glut of gravitational-wave detections

#31

Post by dekhn »

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…

Has LIGO ever responded to Sabine Hossenfelder's claims? http://backreaction.blogspot.com/2019/09/whats-up-with-ligo....

Re: Astrophysicists unveil glut of gravitational-wave detections

#32

Post by DrBazza »

jaspax wrote: post #4
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…

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.

Close by, interesting astronomical events are rare.

The last decent naked eye supernova was the crab nebula in 1054.

It would be a real shame to miss the next one in this galaxy.

Other "rare" (non-gravitational wave) events I can think of are: the Shoemaker Levy comet hitting Jupiter, the Carrington Event in 1859, Betelgeuse dramatically dimming (last year).

Re: Astrophysicists unveil glut of gravitational-wave detections

#33

Post by queuebert »

markus_zhang wrote: post #24

Just curious, if we have gravitational waves, what are the wave lengths?

The orbital period of the merging objects is ~ 1 ms near the end, and gravitational waves propagate at the speed of light, so I'd estimate that the wavelength would be ~ 3e5 x 1e-3, or in the neighborhood of hundreds of kilometers.

Re: Astrophysicists unveil glut of gravitational-wave detections

#34

Post by DrBazza »

dekhn wrote: post #31
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…

Has LIGO ever responded to Sabine Hossenfelder's claims? http://backreaction.blogspot.com/2019/09/whats-up-with-ligo....

I thought that 2019 article is now "answered" by the fact that we have multi-messenger observations of gravitational wave events that confirm fading light curves.

Re: Astrophysicists unveil glut of gravitational-wave detections

#35

Post by [deleted] »

pinko wrote: post #22
mabbo wrote: post #20

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?

Additional detectors improve our ability to detect somewhat (assuming they're of similar sensitivity -- otherwise they can actually hurt our overall network sensitivity!). But the _real_ advantage is in source localization to guide multi-messenger (optical/gamma/neutrino) followup, which is where many of the most important discoveries will come from. It's like triangulation. Given that an observatory costs on the ord…

[deleted]

Re: Astrophysicists unveil glut of gravitational-wave detections

#36

Post by airstrike »

pinko wrote: post #16
im3w1l wrote: post #15

Earlier quoted context omitted.

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…

Thank you for all these replies and for the fantastic work you and the team do.

This is now my favorite AMA

Re: Astrophysicists unveil glut of gravitational-wave detections

#38

Post by t849846224 »

DrBazza wrote: post #32
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.

Close by, interesting astronomical events are rare. The last decent naked eye supernova was the crab nebula in 1054. It would be a real shame to miss the next one in this galaxy. Other "rare" (non-gravitational wave) events I can think of are: the Shoemaker Levy comet hitting Jupiter, the Carrington Event in 1859, Betelgeuse dramatically dimming (last year).

Last 'decent' naked eye supernova was surely Kepler's Supernova of 1604. And the recent fading of Betelgeuse wasn't all that unusual for a fairly typical red supergiant pulsating star.

Re: Astrophysicists unveil glut of gravitational-wave detections

#39

Post by wpietri »

TheOtherHobbes wrote: post #11
wpietri wrote: post #9

Earlier quoted context omitted.

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.

Yes, that's where the practicality comes in. But I'm sure there are people who have FOMO over all that data collection we missed over the last 14 billion years. And that's good! Maybe somebody will come up with something clever that is better than nothing. E.g., all the CMB work: https://en.wikipedia.org/wiki/Cosmic_microwave_background

Re: Astrophysicists unveil glut of gravitational-wave detections

#40

Post by ww520 »

pinko wrote: post #28
ww520 wrote: post #23

Earlier quoted context omitted.

The next stage should be putting them in space. Vibration on earth is a huge problem. Space has a much more stable environment. Also the distance between the laser detectors can be far, greatly enhancing the magnifying power.

In terms of the science, land-based and space-based GW detectors are complementary, as they detect GW waves at very different frequencies. One doesn't replace the other. There are also serious (if obviously longshot) efforts by colleagues of mine to propose moon-based GW detectors: https://indico.ego-gw.it/event/263/

Isn’t to detect different frequencies it’s a matter of varying the distance between the detectors? Space based detectors can be placed arbitrary close or far, moved at will. Ground based is fixed. Also I remember isolation from Earth’s vibration was a huge if not the biggest engineering challenge. There’s no such problem in space.
Post reply on HN