[CloudZ1116]

http://www.ligo.org/news.php

Looks like Einstein was right... again 
Hopefully this one holds up (not to say there's any reason for it not to as of now). However I imagine after the disappointment with BICEP2 that they'd scrutinize their data more this time around.

[praseodym]

Find the PDF here:

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.061102

Absolutely sensational! Congrats

[NGTM-1R]

http://www.ligo.org/news.php

Looks like Einstein was right... again 
Hopefully this one holds up (not to say there's any reason for it not to as of now). However I imagine after the disappointment with BICEP2 that they'd scrutinize their data more this time around.

They've apparently been sitting on it since September and didn't actually have firm plans to announce until last Saturday, so one assumes that was when they were confident.

[Mongoose]

**** yeah science!

[CloudZ1116]

I was actually at the Hanford location of LIGO back in 2011, as part of a tour organized by the Society of Physics Students at the University of Washington. That was my senior year of undergrad. I distinctly remember the guy there saying they had been up an running for a few years but hadn't found anything yet, but that was okay because they hadn't expected to find anything with their current capabilities. He also said something along the lines of "Assuming funding holds up, we'll be upgrading to Advanced LIGO in another few years; maybe then we'll be able to find something."

Fast forward to five years later, and ... yeah. I've been out of academia since I finished undergrad, but it's stuff like this that makes me kind of look back and wish I went to grad school.

[watsisname]

For the study of general relativity and black holes, this is the coolest thing.  First unambiguous detection of gravitational waves, to 5.1-sigma!  Characterization of the source as a pair of merging black holes, including the ringdown (an important prediction for how the resulting black hole radiates away irregularities to obey the no hair theorem -- a black hole must be described only by mass, charge, and spin, and have no other distinguishing features.)  The data showing this are gorgeous.   And check out the relative velocity curve.  They merge at almost 60% the speed of light!

Finally all major predictions of general relativity have been proven, as well as a number of important features in the strong-field regime of black holes.  Einstein wins again!  Plus this opens up a whole new window in observational astronomy.  With future generations of detectors we may even peer through the CMB, to the first moments after the Big Bang!

**** yeah, science!

[Mongoose]

Fast forward to five years later, and ... yeah. I've been out of academia since I finished undergrad, but it's stuff like this that makes me kind of look back and wish I went to grad school.

Heh, I'm pretty much in the same boat, though I never could have hacked it in grad school.  On top of this, I just went to a lecture by the principal investigator on New Horizons yesterday, and I came away feeling ridiculously jealous of the people who do this stuff for a living.

[The E]

From the @MicroSFF twitter:

"Dude!"
"Dude!"
"Grav waves! Rad?"
"Cosmic!"
"Surfable?"
"Dude, any wave is!"
"Dude! Let's build a board!"
-- From 'History of FTL travel'

[Dragon]

This is awesome news. It seems that we really got them this time. One more big question answered.

Fast forward to five years later, and ... yeah. I've been out of academia since I finished undergrad, but it's stuff like this that makes me kind of look back and wish I went to grad school.

Heh, I'm pretty much in the same boat, though I never could have hacked it in grad school.  On top of this, I just went to a lecture by the principal investigator on New Horizons yesterday, and I came away feeling ridiculously jealous of the people who do this stuff for a living.

As someone who recently switched from studying physics to biophysics (a lot lighter on math, but has chemistry and biology), I can tell you that it's only that fun when you sum it up in a lecture. Actually getting those results can be a very tedious work. I don't know how exactly it works with spacecraft data specifically (I worked in a crystallography lab during the holidays), but generally, it mostly boils down to generating a plot of the data you have and checking whether it conforms to what you expect to have. In the lab I briefly worked in we also had to move the samples around the vac chamber, but if all manipulators could be remotely controlled (it depends on what you're doing and with what equipment), we'd only go down to the lab if there was something big to be done (like heating the whole thing up to clean it, or fixing a problem), which doesn't happen often. Also, the more "physical" you get (what I did had a lot to do with chemistry), the less tangible it gets. Playing around with curves can be fun, but it's much less exciting than it sounds in the lectures.

That said, the moment in which they realized they had found gravity waves probably made up for any amount of tedium they went through to get that data.

[666maslo666]

What would be the effects of this gravitational wave on a human being located lets say, million kilometers from the merger? 1AU? 1 light year? Cant find anything on google.

[watsisname]

You'd probably feel nothing, for any of those distances.

The energy carried by a gravitational wave follows the inverse square law, but the stretching (strain) decreases proportionally to distance.  So if you're twice as far away, you're stretched half as much.  The distance of this merger isn't very well constrained (410Mpc +/- ~170Mpc), but let's suppose it's 410Mpc (about 1.3 billion light years).  The strain produced by the waves here on Earth was 1x10^-21.  That means it stretched humans on Earth by by about a millionth the width of a proton as it passed through us.

If you were one light year away from the merger, then the strain would be 1.3 billion times stronger, so you'd be stretched by... about 1% the width of a hydrogen atom.  Still totally unnoticeable.

At 1AU, this stretching of your body increases to about a hundred nanometers.  This is about the size of the smallest thing visible to an optical microscope.

At 1 million km, the strain rises to 10^-5.  Now we're getting somewhere.  This is approaching the width of a human hair.  Would you feel it?  I honestly don't have a clue.  No person has ever been subjected to anything like this before. 

What if you got closer?  The black holes were each about 30 solar masses, which makes them about 200km wide.  So, what if you went up to 1000km distance at the moment they merged?  Then the strain is 10^-2.  This stretches you by nearly an inch!  And as it stretches you one way, it also squeezes you in the other, and this alternates several times within a single second as waves from the final in-spiral rush past you.

You would definitely feel this.  I doubt it would be pleasant.

Unfortunately, you wouldn't be able to get this close to this merger anyway.  At that distance, the regular old tidal forces would be extremely lethal (several hundred G's difference between your head and feet).

You could probably get close enough to a supermassive black hole merger to feel the gravitational waves and not worry about the tidal forces.  But those are exceptionally rare events.

[Phantom Hoover]

That tiny bit of strain must be carrying a hell of a lot of energy, then.

[CP5670]

This is a big finding. As said earlier, the effect of a gravitational wave at this distance is tiny and very hard to measure.

Find the PDF here:

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.061102

Absolutely sensational! Congrats

We were laughing at work about the huge list of authors, which is common in experimental papers but not math or theory ones. The first Abbott (out of three) will be associated with this discovery forever, and apparently a few of the other authors are dead.

[watsisname]

It's a BIG project.

That tiny bit of strain must be carrying a hell of a lot of energy, then.

I believe the technical term is a metric ****load.  In the final second of the merger, about three solar masses worth of energy is emitted as gravitational waves.  This is greater "luminosity" than the light of all the stars in the universe!

[Dragon]

We were laughing at work about the huge list of authors, which is common in experimental papers but not math or theory ones. The first Abbott (out of three) will be associated with this discovery forever, and apparently a few of the other authors are dead.

And of course, it will only ever be cited as "Abbot et al." But that's the reality of experimental physics these days. In order to do anything truly innovative you need mindboggingly enormous projects. Thousands of staffers, billions of dollars and an army of scientists are needed to confirm what one guy figured out and calculated while working in a patent office near the beginning of the previous century.

[Phantom Hoover]

For those of us keeping track of the running Dragon vs. reality score, we have another point for reality, as general relativity was in fact developed by one guy and also several of his colleagues working in the best physics departments of the age.

[Mongoose]

To be fair, Einstein did throw down his huge 1905 stuff while working in said patent office.  It's just that by the time another decade had rolled by, he was kind of a big deal.

[Phantom Hoover]

Even special relativity is ~mostly built up of components invented outside that patent office. There's a reason that relativity is concerned with Lorentz groups acting on Minkowski space, not Einstein groups acting on Einstein space.

[Dragon]

The day you realize that "exaggeration for humorous effect" is a thing will be a good day. The day you learn to understand it will be an even better one, though I feel a few more great discoveries will happen in the meantime...

Even special relativity is ~mostly built up of components invented outside that patent office. There's a reason that relativity is concerned with Lorentz groups acting on Minkowski space, not Einstein groups acting on Einstein space.

Yeah, he didn't invent addition nor calculus, either, and both are used frequently in his theories. What Einstein did was to offer a physical interpretation for mathematical constructs that already existed before. Most notably the work of Poincaré, who was a hair's breadth from discovering Special Relativity. He had the math figured out, but did not realize the implications and insisted it was just a useful mathematical trick. The French still haven't forgiven him for that. Remember that line about "standing on the shoulders of giants"? The last people who could really say they truly invented something "from scratch" lived in antiquity. Every discovery can be said to be built up of components invented by someone else.

[watsisname]

Fun factoid:

If this black hole merger had happened in the Andromeda Galaxy, and if the energy emitted as gravitational waves was instead emitted as visible light, then it would (briefly) appear in the sky as bright as the Sun.