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#40
by
Star One
on 11 Feb, 2016 14:37
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Signal detected 14 September, 2015.
The two black holes are indeed about 30 solar masses. They are about 1.3 billion light years away.
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#41
by
ugordan
on 11 Feb, 2016 14:42
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The two black holes are indeed about 30 solar masses. They are about 1.3 billion light years away.
Well, *were*. It's now just one black hole.
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#42
by
as58
on 11 Feb, 2016 14:50
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This time the rumours were exactly right, except that the papers are published in PRL and ApJ instead of Nature.
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#43
by
eeergo
on 11 Feb, 2016 15:04
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Kip Thorne cannot wait to ride those waves orbiting one of those mergers
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#44
by
eeergo
on 11 Feb, 2016 15:07
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20 ms merger. During that time, the energy output was 50 times the energy released by ALL the stars in the Universe.
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#45
by
Star One
on 11 Feb, 2016 15:09
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The signal came from the Southern sky, in the rough direction of the Magellanic clouds, the satellite galaxies of the Milky Way. At 1.3 billion light years away, however, it is very far beyond the Magellanic clouds, deep in intergalactic space somewhere.
We have only seen spacetime like the surface on a calm ocean until now, says Thorne. Now, we are seeing a storm!
The ‘storm’, meaning the collision of the black holes, lasted for just 20 milliseconds. In that brief moment, it generated 50 times the power of all the stars in the Universe put together.
It was the equivalent of taking three stars, each the size of the Sun, and annihilating them into pure energy. Wow!
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#46
by
Rocket Science
on 11 Feb, 2016 15:12
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"Einstein would be beaming today"
France Cordova
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#47
by
eeergo
on 11 Feb, 2016 15:13
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#48
by
Star One
on 11 Feb, 2016 15:14
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Dr Ed Daw has been researching gravitational waves with LIGO since 1998. He works in the Physics at the University of Sheffield, and sends the following reaction.
Discoveries of this importance in Physics come along about every 30 years. A measure of its significance is that even the source of the wave - two black holes in close orbit, each tens of times heavier than the sun, which then collide violently, has never been observed before, and could not have been observed by any other method. This is just the beginning.
Imagine that your T.V. had only ever received one channel on which the shows were all rather similar to each other. One day a second one appeared which showed completely different programs, like nothing that had ever been broadcast on the old channel. Wouldn’t you want to switch over? By detecting this signal, LIGO has effectively tuned in to a new channel - a completely new way of observing the Universe.
Gravitational waves are so completely different from light, we’re probably only just beginning to understand how they reflect and shape our Universe. For example, a gravitational wave will propagate almost completely unaltered through entire planets, star systems, galaxies....how different is that from the radio waves that your mobile phone picks up - even getting too close to a building can disrupt those signals. Light, or more generally electromagnetic waves are so much more vulnerable to interference than gravitational waves.
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#49
by
eeergo
on 11 Feb, 2016 15:21
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Advanced LIGO is still expected to increase its sensitivity by a factor of 3.
It is expected this year more signals are going to be detected.
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#50
by
Star One
on 11 Feb, 2016 15:26
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Thorne says that we expect to see more signals from similar sources within the next year. Tweeks and improvements will advance LIGO’s sensitivity by about three times. He promises, “A huge richness of gravitational wave signals in LIGO.”
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#51
by
eeergo
on 11 Feb, 2016 15:34
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Signal-to-noise ratio of 24, according to the paper's abstract (which is the only thing I can access right now since APL is down :O )
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#52
by
eeergo
on 11 Feb, 2016 15:36
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VIRGO (another detector in Italy with similar sensitivity) will join the network this year, improving the collaboration's ability to locate the sources.
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#53
by
eeergo
on 11 Feb, 2016 15:39
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Graviton mass limit has been lowered to 10^-55 kg (!!!!), basically confirming it's massless.
Whether or not it exists, or in general how Quantum Gravity may be formulated, is still up for debate. It has just been confirmed gravitational waves propagate at the speed of light.
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#54
by
Star One
on 11 Feb, 2016 15:52
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Criticism for NASA.
Rainer Weiss laments NASA’s decision to pull of the space-based gravitational wave observatory LISA, and praises Europe’s determination to ‘go it alone’ with the eLISA mission and LISA Pathfinder. But he hopes for a new collaboration.
@DrStuClark Gravitational Waves sound like Radiohead's Planet Telex intro, from album The Bends. #spooky
https://mobile.twitter.com/ClickConsultLtd/status/697819704732291072?ref_src=twsrc%5Etfwfinal question of the webcast press conference is whether LIGO has seen other signals. Gonzalez answers very carefully placing the emphasis back on the signal announced today. As she finishes one of her fellow panellists quips ‘that didn’t even sound rehearsed’.
Hmmm. What should we make of that?
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#55
by
sghill
on 11 Feb, 2016 16:00
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Imagine that your T.V. had only ever received one channel on which the shows were all rather similar to each other. One day a second one appeared which showed completely different programs, like nothing that had ever been broadcast on the old channel. Wouldn’t you want to switch over? By detecting this signal, LIGO has effectively tuned in to a new channel - a completely new way of observing the Universe.
Gravitational waves are so completely different from light, we’re probably only just beginning to understand how they reflect and shape our Universe. For example, a gravitational wave will propagate almost completely unaltered through entire planets, star systems, galaxies....how different is that from the radio waves that your mobile phone picks up - even getting too close to a building can disrupt those signals. Light, or more generally electromagnetic waves are so much more vulnerable to interference than gravitational waves.
I'm just going to point out that if I wanted to create the perfect SETI signal. This would be the way to do it...
Our technology may have just reached the point where we can begin to hear constant beacons from civilizations though out the universe since the dawn of time that can both detect and generate gravitational waves.
We can take any discussion of SETI over to a SETI thread:
http://forum.nasaspaceflight.com/index.php?topic=39571.msg1490597#msg1490597
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#56
by
as58
on 11 Feb, 2016 16:02
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final question of the webcast press conference is whether LIGO has seen other signals. Gonzalez answers very carefully placing the emphasis back on the signal announced today. As she finishes one of her fellow panellists quips ‘that didn’t even sound rehearsed’.
Hmmm. What should we make of that?
Rumours have been about (at least) two signals and given that they were almost exactly right about the details of the first detection, I'm pretty sure they're also right about there already being another.
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#57
by
eeergo
on 11 Feb, 2016 16:14
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Some more details from the paper:
- Signal GW150914 was recorded on September 14, 2015 at 09:50:45 UTC, and was automatically selected as interesting 3 minutes later.
- The signal took ~7ms to arrive from Louisiana to Handford, providing the clues about its origin in the Southern sky.
- No other detector was observing at the time (VIRGO was being upgraded, GEO600 wouldn't be sensitive and anyway was not in observational mode).
- Raw signal is actually audible by human ears
in the 35-150 Hz range, and is 8 cycles long.
- AdvLIGO's sensitivity is only in this band because of "photon shot" noise above (I suppose that means the frequency of the laser on the mirrors) and several other noises below. There are still "peaks" of noise in the window because of calibration channels and power grid noise.
- Pressure in the volumes where the beam passes is <1µPa = 10^-11 atm: practically the
"atmospheric pressure" at the ISS altitude (10^-12 atm).
- Injections of fake signals for verification is done through pumping sample signals with the laser.
[more on this post
http://forum.nasaspaceflight.com/index.php?topic=39297.msg1490665#msg1490665]
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#58
by
sanman
on 11 Feb, 2016 16:19
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What will Gravity Astronomy mainly be aimed at uncovering? Presumably, it's going to be biased towards more massive events - big stuff like black holes and galaxies colliding, or neutron stars.
Besides investigating astrophysical phenomena, how could Gravity Astronomy answer questions in fundamental physics?
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#59
by
Star One
on 11 Feb, 2016 16:24
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What will Gravity Astronomy mainly be aimed at uncovering? Presumably, it's going to be biased towards more massive events - big stuff like black holes and galaxies colliding, or neutron stars.
Besides investigating astrophysical phenomena, how could Gravity Astronomy answer questions in fundamental physics?
It can look through the barrier around the Big Bang.
Imagine that your T.V. had only ever received one channel on which the shows were all rather similar to each other. One day a second one appeared which showed completely different programs, like nothing that had ever been broadcast on the old channel. Wouldn’t you want to switch over? By detecting this signal, LIGO has effectively tuned in to a new channel - a completely new way of observing the Universe.
Gravitational waves are so completely different from light, we’re probably only just beginning to understand how they reflect and shape our Universe. For example, a gravitational wave will propagate almost completely unaltered through entire planets, star systems, galaxies....how different is that from the radio waves that your mobile phone picks up - even getting too close to a building can disrupt those signals. Light, or more generally electromagnetic waves are so much more vulnerable to interference than gravitational waves.
I'm just going to point out that if I wanted to create the perfect SETI signal. This would be the way to do it...
Our technology may have just reached the point where we can begin to hear constant beacons from civilizations though out the universe since the dawn of time that can both detect and generate gravitational waves.
We can take any discussion of SETI over to a SETI thread: http://forum.nasaspaceflight.com/index.php?topic=39571.msg1490597#msg1490597
Time to observe Tabby's star.
