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A Fourth Gravitational Wave Has Been Detected (theguardian.com)
An anonymous reader quotes a report from The Guardian: Astronomers have made a new detection of gravitational waves and for the first time have been able to trace the shape of ripples sent through spacetime when black holes collide. The announcement, made at a meeting of the G7 science ministers in Turin, marks the fourth cataclysmic black-hole merger that astronomers have spotted using Ligo, the Laser Interferometer Gravitational-Wave Observatory. The latest detection is the first to have also been picked up by the Virgo detector, located near Pisa, Italy, providing a new layer of detail on the three dimensional pattern of warping that occurs during some of the most violent and energetic events in the universe.
A tiny wobble in the signal, picked up by Ligo's twin instruments and the Virgo detector on 14 August, could be traced back to the final moments of the merger of two black holes about 1.8 billion years ago. The black holes, with masses about 31 and 25 times the mass of the sun, combined to produce a newly spinning black hole with about 53 times the mass of the sun. The remaining three solar masses were converted into pure energy that spilled out as deformations that spread outwards across spacetime like ripples across a pond. Detecting these tiny distortions has required detectors sensitive enough to measuring a discrepancy of just one thousandth of the diameter of an atomic nucleus across a 4km laser beam. A paper about the latest discovery has been accepted for publication in the journal Physical Review Letters.
A tiny wobble in the signal, picked up by Ligo's twin instruments and the Virgo detector on 14 August, could be traced back to the final moments of the merger of two black holes about 1.8 billion years ago. The black holes, with masses about 31 and 25 times the mass of the sun, combined to produce a newly spinning black hole with about 53 times the mass of the sun. The remaining three solar masses were converted into pure energy that spilled out as deformations that spread outwards across spacetime like ripples across a pond. Detecting these tiny distortions has required detectors sensitive enough to measuring a discrepancy of just one thousandth of the diameter of an atomic nucleus across a 4km laser beam. A paper about the latest discovery has been accepted for publication in the journal Physical Review Letters.
How about, uh, the last 48 hours. Seriously guyz, to the extent that you're able to divulge, what the hell happened? https://www.theregister.co.uk/2017/09/27/faulty_data_center_takes_out_sourceforge/ Because we're glad you're back, but we really missed you.
Test, is it working now?
One of the three are here.
"The gravitational waves were detected on Aug. 14, first at the Livingston, La., observatory. A few thousandths of a second later, they were detected at the Hanford LIGO and shortly after that at the Virgo observatory." http://www.tri-cityherald.com/...
Sounds useful, moving one thousandth of the diameter of an atomic nucleus every 2 weeks.
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I am not a physicist, so this is just me muddling through, but why do you think that an 8 or 9 minute delay in the gravity force would cause Newtonian physics not to work? If the attractive force due to gravity is constantly in effect, it wouldn't matter where the planet Earth was 8 or 9 minutes prior to its present location, the force would have still been felt. If the force suddenly switched off it would be interesting, because theoretically the planet would continue to orbit for another 8 or 9 minutes, but it would require a sensor much closer to the sun (that could survive the loss of the attractive force, and that could be retrieved and accessed later) with a synchronized clock to show that the event that switched off gravity happened earlier (because no evidence of the event could arrive at planet Earth earlier than the loss of gravity because of the universal speed limit).
Note that gravity seems to pull the Earth toward the Sun.
If gravity were acting faster then lightspeed, it would appear to pull us toward where the Sun was several minutes (depending on how ftl gravity was, could be anywhere up to about 500 seconds ago) in the past.
Do remember that when you look at the Sun, you're not looking at where it is NOW, but where it was when the light was emitted....
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These are some of the rarest astronomical bodies in the universe and we've already detected 4 of them colliding? Wow maybe they are more common than we thought.
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Gravity moves at the speed of light. This is one of the reasons why Einstein developed the theory of general relativity. Newton's formulas only work when the speed of gravity doesn't matter. I don't know too much details though.
What I also wonder is, why do we detect gravitational waves? Are they only moving the matter, but not so much the photons if the laser beam? If they would move everything in the same way it should be quite difficult to detect something. Though I think some theorists said the same until the first detection
The space that the photons are in is what changes size. To measure it they have two perpendicular "arms" in each detector. When the distance of space changes as a wave goes by, the change in each arm is different; they compare the two and that's when they can detect the ripples.
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If you acknowledge that space and time are linked by the fact that it takes time to traverse space, it is therefore only logical to conclude that manipulations in space also cause manipulations in time. This is what the gravity waves are and why LIGO detects them the way it does. The shape of space changes which causes a disruption in the timing of laser pulses going down tubes.
Your example of the Sun and Earth is complicated. Don't view the Sun as a beam simply transmitting gravity to Earth. Gravity waves are radiating outwards in 3D space in all directions at all times. The plane on which the Earth resides looks like an outward moving disc. As each pulse of gravity reaches Earth, it pulls Earth slightly towards the Sun and into the path of other gravity waves that would have been emitted right after the initial one. This process happens over and over and over and what you get is the elliptical orbit that we see today. The angles and speed of transit change as the rate at which the Earth passes through these gravity waves changes and you get an asymmetric version of the underlying phenomena.
The gravity waves travel at the same speed as photons so they don't interact. What you record in the experiment is the change in the environment outside a constant stream of photons. Photons are emitted at timed intervals and will either bunch up or spread out at the detectors based on how the detector moved around in relation to the photons over time.
NPR (Nation Public Radio) posted a story on this:
http://www.npr.org/2017/09/27/...
At the end of the story they said that since it was 2 black holes, it was unlikely that there would be any light from the event. What was interesting, was that they stated that there were unconfined reports of either a neutron star colliding with a black hole or with another neutron star a few days later. If this observation is confirmed, then there is a possibility that light could have been also observed from that event.
Why has LIGO on recently defected waves if it has been running for many years. Did they do some sort of upgrade?
Praxis?
Don't view the Sun as a beam simply transmitting gravity to Earth. Gravity waves are radiating outwards in 3D space in all directions at all times.
Well said. I would just add something someone told me once when I was pondering the same question. If the sun instantly disappeared, the Earth would continue in its orbit undisturbed for roughly eight minutes. And, of course, it would continue to be heated and lit for the same time.
Did I read it correctly that 3 solar masses were converted to energy? Over what period of time I wonder. Our own sun's total output would not consume all its mass over billions of years.
How big a blast zone did that leave? I can imagine star systems for light years around could have been burnt, destroying civilizations. Has anyone done the numbers?
The gravity wave moves at the speed of light. By the time it reaches Earth, the displacement is one thousandth of the diameter of an atomic nucleus.
Makes me wonder why we shouldn't see gravity waves creating refractive distortions in the surrounding space, much the same way that explosions do on Earth
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Sun is moving at ~200km/s
It's ~8 light-minutes away
It's ~1.391 x 10^6 km in diameter
Conclusion, it's moved ~1/13th of it's diameter
This is basically invisible if we're in the path (at its pro- or retrograde) ... and also irrelevant when viewing the sun perpendicular to its movement :)
When three solar masses are converted from mass into pure energy (E = m . C^2) , that's a tremendous amount of energy. Mass/Inertia is due to the attraction of the quantum foam to atomic nucleii. When those nucleii disappear and all that mass is converted into photons, the stretched space time contracts and expands.
Anything with mass (protons, neutrons and electrons) has inertia, while photons don;t have mass/
Similar to the way tectonic plates creating a tsunami. Imagine the three ends of each detector are beach balls floating on a ocean. So long as the ocean is calm, these will stay in place. Whenever a wave rolls by. the distance between those balls will change.
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I just want a Ligo app so that the moment Ligo detects a signal I get notified with a chirp and a vibration, so that I can almost feel the wave as it passes.
~1/13th of the Sun's diameter is about 4 minutes of arc. Trust me, we can measure things MUCH smaller than 4 minutes of arc with trivial effort. We'd have noticed.
Also, don't forget that the planet is moving relative to the Sun.
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This always happens during times of intensive solar flares.
I'm thinking the Electric Universe's answer is right.
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Yup :)