Gravity Waves, Just the Fact(oids)

[alinsa]

For those who couldn't make it through the epic tome I just posted. Just the factoids from the gravitational wave announcement:

• The LIGO project has announced what is pretty solid evidence that they have successfully detected gravitational waves. The video of the actual announcement is here.
  
• Gravity is, effectively, distortions in the shape of

Comments

[tuftears]

What I don't get is how they manage to sort out direction and distance with gravity waves. -_-

[stickmaker]

The detector has two legs. Though they really need three axes for good precision.

Additional information:

There were two gravity wave detectors involved, widely separated enough to use light speed delay to get a general direction. Further analysis of the signals combined with more traditional astronomical observations identified the culprit(s).

[tuftears]

Dang. That's a lot of very detailed analysis, I'd have expected you'd need at least three and perhaps four for spatial location.

[alinsa]

Yeah, the analysis is pretty impressive. Admittedly, the direction they were able to get was just a general direction (certainly nothing precise enough that you could try to point a telescope at it or something), but as more detectors come online (there are more planned!), they'll be able to make those measurements more and more precise. Which, I have to say, is really awesome.

Also, to be precise (@stickmaker), the two axes weren't for determining direction, they were for determining polarization, since otherwise all you know is that space smushed, but not really in which direction it is smushing (which is a thing unrelated to which direction it's coming from).

[stickmaker]

It was actually 2.99 solar masses. :-)

I know - barely - Keith Thorn, one of the authors of the paper. He is in a fannish group I belong to, General Technics. He was posting in the group's e-mail list this morning about all the work they did to make sure this was legit. Which is why they wouldn't confirm for so long. Keith said that even his mother heard the rumors and was pestering him for details. :-)

There had briefly been a false positive before, caused by a test signal being introduced by the testing people which the detector people weren't expecting. This time they pled innocent. All other known sources checked clean, as well.

[alinsa]

I finally got a chance to read the full paper, and yeah, the amount of effort they went through to verify that there was actually a signal was really quite impressive. My favorite was the 'subtract out your theoretical model of what the signal should look like, then take the residual and see if it differs statistically from the normal background noise' (which it shouldn't). That's durned clever (though I imagine not uncommon).

Done this week (20160207Su - 13Sa)

[livejournal]

User mdlbear referenced to your post from Done this week (20160207Su - 13Sa) saying: [...] (Alinsa [...]

[level_head]

Happy birthday, Alinsa.

May the day be one of significant gravity. *waves*

===|==============/ Keith DeHavelle