We have a new "GW"!

[anthony]

It's quite something to be living in such interesting times!

It is past me to grasp the enormity and ramifications of Gravitational Waves, but the first person who came to mind is Stephen Boydstun who could fill us in...(?)

[BaalChatzaf]

18 minutes ago, anthony said:

It's quite something to be living in such interesting times!

It is past me to grasp the enormity and ramifications of Gravitational Waves, but the first person who came to mind is Stephen Boydstun who could fill us in...(?)

Have a look here:  http://www.space.com/17661-theory-general-relativity.html

 The spacetime continuum bends and wiggle according to the effects of mass.  When two big hunks like a pair of black holes collide the space time manifold  stretches and squeezes.

 

Drop a big rock into a still point and see what  the water does.  This  is just a simplified version of gravity waves which operate in 4 dimensions.

[anthony]

16 hours ago, BaalChatzaf said:

Have a look here:  http://www.space.com/17661-theory-general-relativity.html

 The spacetime continuum bends and wiggle according to the effects of mass.  When two big hunks like a pair of black holes collide the space time manifold  stretches and squeezes.

 

Drop a big rock into a still point and see what  the water does.  This  is just a simplified version of gravity waves which operate in 4 dimensions.

Yes GW eventually and broadly makes sense, thanks. The proving of Einstein's theory 110 years later also is what gets me. Imagine knowing your life's work can't be validated during your lifetime, if ever. Science is patient.

[BaalChatzaf]

55 minutes ago, anthony said:

Yes GW eventually and broadly makes sense, thanks. The proving of Einstein's theory 110 years later also is what gets me. Imagine knowing your life's work can't be validated during your lifetime, if ever. Science is patient.

101 years after.  Einstein finally nailed General Relativity in 1915.   After Einstein lectured at Gottingen, Hilbert  found the field equations in a matter of weeks.  Einstein had struggled with them for years.   Hilbert nearly scooped Einstein, but he said Einstein deserves the praise because Einstein blazed the the trail.  Einstein struggled with GR from 1907 to 1915  and he nearly had a nervous breakdown from the effort.  Many people were near to getting Special Relativity other than Einstein,  but GR was  an Einstein original  from the the git-go.  If Einstein had died in 1905 prior to publishing Special Relativity  it would have been found by several others.  Special Relativity was implicit in Maxwell's Theory of the Electromagnetic Field.  That theory was Lorentz Invariant right out of the box.  In fact it was Maxwell's (and Faraday's)  theory  that gave Einstein the clue to Special Relativity.

[Guyau]

Pittsburg Post-Gazette – 11 February 2016*

This discovery “will stand out among the major achievements of 21^st Century science.” – Abhay Ashtekar

Scientific American

Gravitational Waves Discovered

The Detection of Gravitational Waves Is a Triumph for Physics

Not All Gravitational Waves Are Created Equal

~~~~~~~~~~~~~~~~

SB – 12/23/13*

Quote

Einstein was the first to realize, in 1916, that his GR equations predicted the existence of gravitational waves under certain conditions. Russell Hulse and Joseph Taylor obtained strong indirect evidence in 1981 for the existence of gravitational waves by observing a reduction in orbital energy from an orbiting pulsar system in the amount predicted by GR for dissipation of that energy in such a system were the energy carried away in gravitational waves.

LIGO aims to detect gravitational waves directly using laser interferometers sited far apart in the US mainland. The sensitivity of the LIGO detectors so far has been only enough to detect gravitational waves resulting from pulsar collapses (a big though rare event) at distances from us wherein hundreds of centuries could go by without a collapse. No waves have been detected at this sensitivity. LIGO is now being enhanced to achieve a sensitivity to binary-pulsar collapses in space much farther from us wherein the total volume would have hundreds of collapses each year. The advanced LIGO* is scheduled to get to work in 2016.

For a look at future interferometer detectors operating from outer space capable of detecting gravitational waves so pervasive that they could be used to infer activities inside the event horizon of a black hole or to infer conditions in the part of the cosmic expansion before the universe lighted up with what is now known as the cosmic background radiation, see the cover article of the October 2013 issue of Scientific American, authored by Ross Andersen.

As I recall, we are to start by setting T to zero:

[BaalChatzaf]

35 minutes ago, Guyau said:

Pittsburg Post-Gazette – 11 February 2016*

This discovery “will stand out among the major achievements of 21^st Century science.” – Abhay Ashtekar

Scientific American

Gravitational Waves Discovered

The Detection of Gravitational Waves Is a Triumph for Physics

Not All Gravitational Waves Are Created Equal

~~~~~~~~~~~~~~~~

SB – 12/23/13*

As I recall, we are to start by setting T to zero:

Very trendy.  When I was a kid,  I had a T-Shirt with Maxwell's Equations.   That was Back in the Day....

[Guyau]

Robert Wald,* writing in General Relativity (1984)*

Quote

One of the most important changes which occurs when one goes from Coulomb's theory of electrostatics to Maxwell's theory of electromagnetism is that the electromagnetic field becomes a dynamical entity. Electromagnetic radiation can propagate freely through spacetime. A similar change occurs when one goes from Newtonian gravitation to general relativity: Gravitational radiation exists [i.e., is implicit in GR, in Einstein's field equation]: i.e., ripples in the curvature of spacetime can propagate through spacetime. (78)

. . . We obtain a very simple expression for the relevant components of the linearized Riemann tensor . . . (Incidentally, this formula shows that the plane wave solutions we obtained above are physically meaningful—that is, that they cannot be eliminated by further gauge transformations—since they produce nonzero curvature.) Thus, in principle, one could detect gravitational radiation by accurately tracking (say, with laser beams) the separation of two masses suspended freely from supports; such a detection scheme may become practical in the near future. . . . The extreme sensitivity required for the detection of gravitational radiation should be stressed. For physically reasonable astrophysical sources of gravitational waves, one does not expect the radiation gauge components . . . in the relevant frequency range to have a magnitude greater than about 10-to-the-minus-17. . . . This means that the fractional relative displacement . . . of the two free masses should not exceed 10-to-the-minus-17, i.e., free masses separated by 1 meter will be displaced by no more than 1/100 of a nuclear diameter by a gravitational wave! (81–82)

"What a piece of work is man. How noble in reason, how infinite in faculty."

[BaalChatzaf]

1 hour ago, Guyau said:

Robert Wald,* writing in General Relativity (1984)*

"What a piece of work is man. How noble in reason, how infinite in faculty."

Teeny Tiny Ripples in the Biggest Pond....

[Guyau]

Such oscillations of the human mind as went into GR and this experiment are the most important sort of reverberations of the universe with itself that we know of so far. No conflation, Bob, of “big” physical size or duration with “importance” in the universe. We are bits of the universe, as you imply, and importance of those bits to us is importance in the universe. It is only in the live universe that there is importance in the universe. It is only to living bits that anything has significance or importance. The rest is just dumb-dead and might as well not exist were there no life in the cosmos. Life in the universe is the only significance, and so far as we know, the human mind is the highest form of life.

[BaalChatzaf]

1 hour ago, Guyau said:

Such oscillations of the human mind as went into GR and this experiment are the most important sort of reverberations of the universe with itself that we know of so far. No conflation, Bob, of “big” physical size or duration with “importance” in the universe. We are bits of the universe, as you imply, and importance of those bits to us is importance in the universe. It is only in the live universe that there is importance in the universe. It is only to living bits that anything has significance or importance. The rest is just dumb-dead and might as well not exist were there no life in the cosmos. Life in the universe is the only significance, and so far as we know, the human mind is the highest form of life.

So far as we know...    However  we are primate hominid version 3.0.  Somehow I cannot accept that our 3 lb brain with its associated mind  is the Last Word  in either Brain or Mind.  The Cosmos is a very big place.  As the late Carl Sagan said it is filled with billyuns and billyuns of stuhrs....   And for that reason I entertain the possibility  that somewhere Out There  there are even smarter sentient beings.  We just have not met up with them, and given cosmic distances we are not likely to.

[Selene]

 

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