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Gravitational Waves Discovered

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beero1000

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http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html

A team of physicists who can now count themselves as astronomers announced on Thursday that they had heard and recorded the sound of two black holes colliding a billion light-years away, a fleeting chirp that fulfilled the last prophecy of Einstein’s general theory of relativity.

That faint rising tone, physicists say, is the first direct evidence of gravitational waves, the ripples in the fabric of space-time that Einstein predicted a century ago. And it is a ringing (pun intended) confirmation of the nature of black holes, the bottomless gravitational pits from which not even light can escape, which were the most foreboding (and unwelcome) part of his theory.


More generally, it means that scientists have finally tapped into the deepest register of physical reality, where the weirdest and wildest implications of Einstein’s universe become manifest.

If replicated by future experiments, that simple chirp, which rose to the note of middle C before abruptly stopping, seems destined to take its place among the great sound bites of science, ranking with Alexander Graham Bell’s “Mr. Watson — come here” and Sputnik’s first beeps from orbit.


“We are all over the moon and back,” said Gabriela González of Louisiana State University, a spokeswoman for the LIGO Scientific Collaboration, short for Laser Interferometer Gravitational-Wave Observatory. “Einstein would be very happy, I think.”


Members of the LIGO group, a worldwide team of scientists, along with scientists from a European team known as the Virgo Collaboration, published a report in Physical Review Letters on Thursday with more than 1,000 authors.


“I think this will be one of the major breakthroughs in physics for a long time,” said Szabolcs Marka, a Columbia University professor who is one of the LIGO scientists.


“Everything else in astronomy is like the eye,” he said, referring to the panoply of telescopes that have given stargazers access to more and more of the electromagnetic spectrum and the ability to peer deeper and deeper into space and time. “Finally, astronomy grew ears. We never had ears before.”
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Nobel prizes all around!
 
There was a peep about this a few weeks ago, that maybe this happened. I remember reading about this facility back in the late 90s and was so disappointed that we'd have to wait to see what it detected. Nothing!

Then they upgraded it and this is a huge observation, a wildly absurd one, to measure waves so unimaginably small. To put it in simple terms, gravitational waves are really fucking small. Smaller than the IQ of a Trump supporter!

My only question is, what do we gain from this observation. Do we need a bunch more to suss them out? Can we tell the source direction?
 
Jimmy Higgins said:
My only question is, what do we gain from this observation. Do we need a bunch more to suss them out? Can we tell the source direction?
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To get exact direction you need 3 interferometers, with two it's a circle in the southern sky.
and distance is 1.3 billion years, I understand.
 
Jimmy Higgins said:
There was a peep about this a few weeks ago, that maybe this happened. I remember reading about this facility back in the late 90s and was so disappointed that we'd have to wait to see what it detected. Nothing!

Then they upgraded it and this is a huge observation, a wildly absurd one, to measure waves so unimaginably small. To put it in simple terms, gravitational waves are really fucking small. Smaller than the IQ of a Trump supporter!

My only question is, what do we gain from this observation. Do we need a bunch more to suss them out? Can we tell the source direction?
Click to expand...

To be precise, the intelligence of a Trump supporter has never been empirically verified, only indirectly assumed.
 
barbos said:
Jimmy Higgins said:
My only question is, what do we gain from this observation. Do we need a bunch more to suss them out? Can we tell the source direction?
Click to expand...
To get exact direction you need 3 interferometers, with two it's a circle in the southern sky.
and distance is 1.3 billion years, I understand.
Click to expand...
That's just incredible!

Can we discern much else from the wave(s)?
 
the @ligo feed on twitter is pretty cool. Apparently it is only 1/3 of its final sensitivity. Noice!
 
Very impressive. I wonder how they know the source of the gravitational waves? Have they eliminated background terrestrial events e.g. Gov Chris Christie doing a cannonball off the high dive at the YMCA?

I remember a few years ago on SETI they thought they found a signal, but it turned out to be from a nearby leaky microwave oven.
 
So, I am trying to figure out the peak power (watts) that this merger produced and compare it to super or hypernovas at peak. Black holes through gravity waves and novas by neutrinos.

Ok, I found it from Kip Thorne:

"The storm was brief — 20 milliseconds — very brief, but very powerful," Thorne said. "The total power output during the collision was 50 times greater than all the power of all the stars in the universe put together."
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I assume observable universe...

I do wish someone would ask him this question, that I hope is coherent:

If a person were located far enough away from the binary black holes to be safe from there gravity before merging, would the merger damage them?

Maybe put another way: what minimum distance a person need to be to avoid damage from the merger?

ETA: damage only from gravitational waves, not radiation.
 
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From a reddit thread, this had me laughing:

Astounding. The Michelson–Morley experiment was done in 1887 to try and detect the differences in the speed of light in perpendicular directions, in an attempt to detect the relative motion of matter through the stationary luminiferous aether ("aether wind"). In 1905, Einstein published a paper first bringing up time dilation, which takes the speed of light as constant and deduces some weird shit that reality should conform to. During 1907-1915 he develops General Relativity, which explains how gravity plays into this. And now, in 2016, a 100 years later; the dude's scientific deductions are still coming true in exciting ways. And, hilariously, the idea of looking at light going in perpendicular directions is again the experiment being done, except with an entirely different outlook on what is expected. What's ironic is we can look at this now as "listening" to the "ether".
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Two stellar mass black holes (36+5-4 and 29+/-4 M_sun) into a 62+/-4 M_sun black hole with 3.0+/-0.5 M_sun c^2 radiated away in gravitational waves. That's the equivalent energy of 5000 supernovae!
Peak luminosity of 3.6+0.5-0.4 x 10^56 erg/s, 200+30-20 M_sun c2 / s. One supernova is roughly 10^51 ergs in total!
Distance of 410+160-180 megaparsecs (z = 0.09+0.03-0.04)
Final black hole spin α = 0.67+0.05-0.07
5.1 sigma significance (S/N = 24)
Strain value of = 1.0 x 10^-21
Broad region in sky roughly in the area of the Magellanic clouds (but much farther away!)
Rates on stellar mass binary black hole mergers: 2-400 Gpc-3 yr-1
Limits on gravitons: Compton wavelength > 10^13 km, mass m < 1.2 x 10^-22 eV / c2 (2.1 x 10^-58 kg!)
 
thebeave said:
Very impressive. I wonder how they know the source of the gravitational waves? Have they eliminated background terrestrial events e.g. Gov Chris Christie doing a cannonball off the high dive at the YMCA?

I remember a few years ago on SETI they thought they found a signal, but it turned out to be from a nearby leaky microwave oven.
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They detected it at both facilities, which are a couple thousand miles apart.
 
Jimmy Higgins said:
thebeave said:
Very impressive. I wonder how they know the source of the gravitational waves? Have they eliminated background terrestrial events e.g. Gov Chris Christie doing a cannonball off the high dive at the YMCA?

I remember a few years ago on SETI they thought they found a signal, but it turned out to be from a nearby leaky microwave oven.
Click to expand...
They detected it at both facilities, which are a couple thousand miles apart.
Click to expand...
Yeah, I never understood the logic of using single telescope to look for aliens. Two or more well separated telescopes seems like a no-brainer.
 
Don't these black holes gain "mass" by gravitational binding energy as they get closer together?

I will take newton's gravity law P.E. = Gm1m2/r
m1=36 solar mass, m2=29 solar mass, r=350 km (wiki)

Then divide by c^2.

G= 6.7*10^-11
Solar mass = 2*10^30 kg
Radius = 3.5*10^5 m
c^2 =9*10^16 m^2

Mass from binding: 8.9*10^30 kg or about 4.5 solar masses.



Does this make any sense, even ass a half assed approximation?
 
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Jimmy Higgins said:
thebeave said:
Very impressive. I wonder how they know the source of the gravitational waves? Have they eliminated background terrestrial events e.g. Gov Chris Christie doing a cannonball off the high dive at the YMCA?

I remember a few years ago on SETI they thought they found a signal, but it turned out to be from a nearby leaky microwave oven.
Click to expand...
They detected it at both facilities, which are a couple thousand miles apart.
Click to expand...

Thanks. Maybe next time I should read the full article first. :o
 
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