LIGO gravitational wave announcement

Pixel42

Schrödinger's cat
Pixel42
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There have been rumours for weeks and mentions in at least one thread, but I think with a press conference just two days away it's time for its own thread.

Here's the Guardian's article:

https://www.theguardian.com/science...acetime-gravitational-wave-discovery-expected

A decades-long search for gravitational waves is expected to end in triumph this week when scientists declare they have discovered ripples in the fabric of spacetime, possibly created by the collision of two massive black holes travelling at close to the speed of light.

First predicted by Einstein, and generated by the most cataclysmic events in the cosmos, gravitational waves stretch and squeeze space and all within it as they spread out across the universe. Their discovery, if confirmed, is certain to earn a Nobel prize.

Scientists have hunted for signs of the waves for decades, but until now, their attempts have been frustrated by false signals and instruments that were not sensitive enough to detect the waves by the time they reached Earth.

That is expected to change on Thursday, when physicists in the US reveal their latest data from an experiment known as LIGO, or the Advanced Laser Interferometer Gravitational-Wave Observatory. The team have detectors in Washington and Louisiana that can spot passing gravitational waves via the minuscule changes in length they produce in two 4km-long pipes.

At a press conference in Washington, LIGO scientists are anticipated to reveal a clear, unambiguous gravitational wave signal. It may have come from two vast black holes, one 29 times more massive than the sun, the other 36 times more massive, spiralling around each other and finally crashing together to form a new black hole 62 times the mass of the sun. For all its heft, the new body may be no more than 200 miles wide.
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Well, I'm glad to see that on this island Earth, an advanced scientist finally constructed a working Interocitor Interferometer.
 
3point14 said:
Are there any potential, practical benefits from this?
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We usually discover this stuff first, and the practical benefits come later.

A few hundred years ago, people used amber to "prank" each other via static electricity. General Relativity was a cool thing, but most things that have since needed it weren't yet invented (like GPS).
 
DuvalHMFIC said:
We usually discover this stuff first, and the practical benefits come later.

A few hundred years ago, people used amber to "prank" each other via static electricity. General Relativity was a cool thing, but most things that have since needed it weren't yet invented (like GPS).
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Oh, don't get me wrong, this was not a prelude to rant against blue sky research.

GPS is my go-to for arguing in favour of such research (relativity and quantum theory both required.)

I was just curious.
 
There are many, many reasons gravity wave discovery will be awesome. First we get a GR test, then we get an astronomy tool---the rumor, in particular, corresponds to a type of binary black hole that's been predicted to arise only from the very earliest batch of stars in the Universe.

There is, however, an additional guilty pleasure I will take on top of that.

http://vixra.org/abs/1103.0048 said:
LIGO, LISA Destined to Detect Nothing

Authors: Stephen J. Crothers

It is claimed that the LIGO and LISA projects will detect Einstein's gravitational waves. The existence of these waves is entirely theoretical. Over the past forty years or so no Einstein gravitational waves have been detected. How long must the search go on, at great expense to the public purse, before the astrophysical scientists admit that their search is fruitless and a waste of vast sums of public money? The fact is, from day one, the search for these elusive waves has been destined to detect nothing. Here are some reasons why.
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Are these the same kind of stardust gravitational waves BICEP2 detected? If not, would there be any similar implications for inflationary cosmology?
 
constantine said:
Are these the same kind of stardust gravitational waves BICEP2 detected? If not, would there be any similar implications for inflationary cosmology?
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No. BICEP2 was looking for the imprint of primordial gravitational waves, which would have been sort of Big Bang leftovers whose wavelengths are a good fraction of the size of the Universe.

LIGO is looking for a burst of gravitational waves emitted, fairly nearby and fairly recently, by a pair of black holes or neutron stars merging. Shorter wavelengths (hundreds of kilometers), higher frequencies (kilohertz). It tells us about astronomy, not cosmology.
 
This could be useful in detecting supernovae before the light reaches us. Light has to pass through the interstellar/intergalactic media and so travels very slightly under the speed of light in an absolute vacuum. As far as we know, nothing impedes the progress of gravity waves.
 
BenBurch said:
This could be useful in detecting supernovae before the light reaches us. Light has to pass through the interstellar/intergalactic media and so travels very slightly under the speed of light in an absolute vacuum. As far as we know, nothing impedes the progress of gravity waves.
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Supernovae are much more nearly spherically symmetric than compact-object mergers, so they're comparatively weak gravitational wave sources; even far-future detector proposals (LIGO upgrades, DECIGO, LISA) could only be sensitive to supernova GW from within the Milky Way---and that means the events will be very rare, one or two per century. (LIGO can search for mergers from thousands of nearby galaxies.)

There is a delay between gravity waves, neutrinos, and light from a supernova, but it's not the interstellar medium---it's the star itself. At the time the GW-emitting part of the supernova is going on, there's still most of a star's worth of hydrogen around it, feeling the impact of various shocks and radiation pressure forces and deciding which way to go. After the GW event has passed, the system still takes a second or so to become transparent to neutrinos, and a few hours to release photons. After that, though, all three components travel through the ISM at speeds indistinguishable from c.
 
Useful background article on the BBC news website: http://www.bbc.co.uk/news/science-environment-35533241

If detection of these waves is now a reality, we are at the beginning of a new era in astronomy - especially once three detectors are online, allowing the source of the ripples to be triangulated.

Gravitational waves will join the myriad types of light, plus some particles like neutrinos, that scientists already use to probe the far reaches of the universe.

Crucially, because they travel straight through matter, nothing can obscure the source of these waves - there are no shadows. And they could offer an unparalleled "view" of objects that don't emit light, like black holes.

This is why gravitational astronomy has been described as listening to, rather than looking at, the cosmos.

Tuck Stebbins, from Nasa's Goddard Space Flight Center, told the AFP news agency that gravitational waves could even be a window - in fact, the only possible window - on the origin of the universe.

"These waves are streaming to you all the time and if you could see them, you could see back to the first one trillionth of a second of the Big Bang," he said.
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Now this is the sort of thread that makes this forum special for me, and why I always find myself coming back, despite everything.

Thanx for the E :D
 
Nice opening to the livestream: "Ladies and gentlemen, we have detected gravitational waves. We did it."
 
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