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That https://journals.aps.org/prl/a... was one hard read, here's one from LIGO explaining gravity waves and their detection http://ligo.org/science/Public...

The second LIGO detector is like 20 miles away, so when a gravity wave comes by I know I felt it :)

Before you get excited it would be wise to wait for confirmation of the existence of gravitational waves from an observatory without the built-in capability of blind injections.

Sorry for being annon, don't want to undo moderation
They checked, no speculation needed
https://dcc.ligo.org/public/01...

-Earthquakes
can produce ground motion at the detectors with frequencies from approximately 0.03 to 0.1 Hz or higher if the epicenter is nearby [10]. R-waves, the highest amplitude component of seismic waves from an earthquake [11], are the most likely to adversely impact data quality by rendering the detectors inoperable
or inducing low frequency optic motion that up-converts to higher frequencies in h(t) via mechanisms such as bilinear coupling of angular motion or light scattering. A network of seismometers installed at the LIGO detectors can easily identify earthquake disturbances.

Inspiral Gravitational Waves

"Inspiral gravitational waves are generated during the end-of-life stage of binary systems where the two objects merge into one. These systems are usually two neutron stars, two black holes, or a neutron star and a black hole whose orbits have degraded to the point that the two masses are about to coalesce. As the two masses rotate around each other, their orbital distances decrease and their speeds increase, much like a spinning figure skater who draws his or her arms in close to their body. This causes the frequency of the gravitational waves to increase until the moment of coalescence. The sound these gravitational waves would produce is a chirp sound (much like when increasing the pitch rapidly on a slide whistle) since the binary system’s orbital frequency is increasing (any increase in frequency corresponds to an increase in pitch)."

Continuous Gravitational Waves

"Continuous gravitational waves are produced by systems that have a fairly constant and well-defined frequency. Examples of these are binary star or black hole systems orbiting each other or a single star swiftly rotating about its axis with a large mountain or other irregularity on it. These sources are expected to produce comparatively weak gravitational waves since they evolve over longer periods of time and are usually less catastrophic than sources producing inspiral or burst gravitational waves. The sound these gravitational waves would produce is a continuous tone since the frequency of the gravitational wave is nearly constant."

Possibly something like Betelgeuse, that throws mass off in a asymmetric manner.

"[Astronomers] noticed a large plume of gas extending outward at least six times the stellar radius indicating that Betelgeuse is not shedding matter evenly in all directions. The plume's presence implies that the spherical symmetry of the star's photosphere, often observed in the infrared, is not preserved in its close environment. Asymmetries on the stellar disk had been reported at different wavelengths."

Sources of Gravitational Waves

"In general, any acceleration that is not spherically or cylindrically symmetric will produce a gravitational wave. Consider a star that goes supernova. This explosion will produce gravitational waves if the mass is not ejected in a spherically symmetric way, although the center of mass may be in the same position before and after the explosion. Another example is a spinning star. A perfectly spherical star will not produce a gravitational wave, but a lumpy star will."

"There are four main sources of gravitational waves caused by different kinds of motion and changing distributions of mass - continuous, inspiral, burst, and stochastic."

Sources of Gravitational Waves

"In general, any acceleration that is not spherically or cylindrically symmetric will produce a gravitational wave. Consider a star that goes supernova. This explosion will produce gravitational waves if the mass is not ejected in a spherically symmetric way, although the center of mass may be in the same position before and after the explosion. Another example is a spinning star. A perfectly spherical star will not produce a gravitational wave, but a lumpy star will."

"There are four main sources of gravitational waves caused by different kinds of motion and changing distributions of mass - continuous, inspiral, burst, and stochastic."

Sources of Gravitational Waves

"In general, any acceleration that is not spherically or cylindrically symmetric will produce a gravitational wave. Consider a star that goes supernova. This explosion will produce gravitational waves if the mass is not ejected in a spherically symmetric way, although the center of mass may be in the same position before and after the explosion. Another example is a spinning star. A perfectly spherical star will not produce a gravitational wave, but a lumpy star will."

"There are four main sources of gravitational waves caused by different kinds of motion and changing distributions of mass - continuous, inspiral, burst, and stochastic."

Sources of Gravitational Waves

"In general, any acceleration that is not spherically or cylindrically symmetric will produce a gravitational wave. Consider a star that goes supernova. This explosion will produce gravitational waves if the mass is not ejected in a spherically symmetric way, although the center of mass may be in the same position before and after the explosion. Another example is a spinning star. A perfectly spherical star will not produce a gravitational wave, but a lumpy star will."

"There are four main sources of gravitational waves caused by different kinds of motion and changing distributions of mass - continuous, inspiral, burst, and stochastic."

Sources of Gravitational Waves

"In general, any acceleration that is not spherically or cylindrically symmetric will produce a gravitational wave. Consider a star that goes supernova. This explosion will produce gravitational waves if the mass is not ejected in a spherically symmetric way, although the center of mass may be in the same position before and after the explosion. Another example is a spinning star. A perfectly spherical star will not produce a gravitational wave, but a lumpy star will."

"There are four main sources of gravitational waves caused by different kinds of motion and changing distributions of mass - continuous, inspiral, burst, and stochastic."

Of course the paper was peer reviewed first. "Science by press conference" is a slur, and a terrible way to do science. This result was detected in September, you ape, and it's not like this is their first publication. They have been grilled over their methodology quite a bit to date, and if you think that this was "rushed through" you clearly have no idea how peer review works.

The actual LIGO Media Advisory is here: http://www.ligo.org/news/media... (with a bunch of links to background info)

Note that this the second indirect evidence for the existence of gravitational waves, the first one was the orbital decay of a binary system that included a pulsar, discovered by Hulse and Taylor (Nobel Prize 1993). Today's result, if confirmed, seems pretty spectacular, and might be rewarded with a second Nobel Prize. For a first direct detection of gravitational waves, we have to wait for first detections by LIGO, Virgo and eLISA.

They specifically talk about the LIGO II http://www.ligo.org/ gravity wave observatory. And yes, they believe that a gravity wave can be detected without having the ability to detect individual gravitons as baryonic particles.

Now my head hurts ... thanx

They specifically talk about the LIGO II http://www.ligo.org/ [ligo.org] gravity wave observatory. And yes, they believe that a gravity wave can be detected without having the ability to detect individual gravitons as baryonic particles.

Yes, and the existence of gravitational waves has already been proved indirectly by the Hulse-Taylor binary pulsar system, which is losing energy at exactly the rate predicted by general relativity. There is really no doubt about the existence of gravitational waves, either theoretically or empirically. LIGO is cool because it could open the door to a new way of doing astronomy, not because there is doubt about the existence of gravitational waves.

Actually, the referenced paper says something else.

They specifically talk about the LIGO II http://www.ligo.org/ gravity wave observatory. And yes, they believe that a gravity wave can be detected without having the ability to detect individual gravitons as baryonic particles.

Also, for what it's worth, it'd be possible to check one way or the other for several billion dollars worth of equipment: three large masses arranged in a scalene triangle with laser interferometers acting as a target plane, with another mass to target the plane at an angle of about 45 degrees relative to the face of the plane would either demonstrate a time base variance between the target masses -- or not. You have to keep the target masses relatively close to each other.

The speed limit on the mass after the slingshot would be about 240,000 KPH. To overcome that problem and get higher speed (we need relativistic speeds for crossing the plane), you need two more masses: one the size of the mass you sling-shotted, the other relatively smaller. From the reference frame of the large and small mass, the are effectively being dropped together onto a stationary object at 240,000 KPH. This will be enough to catapult the smaller mass up to relatavistic speeds for collision with the virtual plane. We don't care if the large slingshot mass and the large target mass survive, we just want the momentum transfer. Here's a nice little demo of the process: http://www.physics.org/interact/physics-to-go/extra-bounce/index.html

--Terry

Here you go: https://gwic.ligo.org/researchpapers/

General relativity does however state that the star is losing KE to gravity waves, this effect is so small that it would probably take many billions of years for the orbit to decay close enough for the star to be destroyed but it's still a noteworthy effect. Such orbital decay is predicted to be responsible for neutron binary collisions though, the best candidates we have for actually *detecting* gravity waves directly with LIGO et. al.

It is only mentioned briefly in the article, but I'll try to elaborate.

Basically gravity waves will stretch space in one direction (say x) and contract space in a perpendicular direction (y). Given this, the "easiest" way to detect gravity waves is to build a very large interferometer. LIGO is the current ongoing gravity wave interferometer, which splits one laser beam into two lasers beams, sending each perpendicularly down a vacuum "hallway" four kilometers long. At the end, the beams are reflected by mirrors. The two lasers meet again after another 4km.

The two beams are recombined afterwards. If the distances the two travel are exactly equal, then the two beams will interfere constructively. But if the lengths which the two beams are stretched/contracted by a passing gravity wave, the beams will interfere since one will be "shifted" (it had to travel a longer/shorter distance. By measuring the interference pattern between theses two beams, and hopefully physicists will be able to detect a gravity wave.

The amount that a gravity wave will shrink/extent one of the beam lines is amazingly small. Each 4km beam line will have it's distance changed by 10^-18 meters, or on the scale of attometers! Because of this, any vibration or local variation will affect the beam length. So the physics who are part of the LIGO collaboration built two such laser devices, one in Livingston, Louisiana and the other in Hanford, Washington. When a gravity wave (from outer space) travels through the earth, hopefully both sites will measure the same small variation, which will correspond to a passing gravity wave.

You can get more information about LIGO at:
LIGO's Home Page

LIGO collaboration page.

Slashdot recently had a science story about LIGO.