
Gravity’s Kiss: The third ripple - dnetesn
http://mitp.nautil.us/feature/159/gravitys-kiss
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Camillo
I'm going to save you some time, having lost mine. The article consists of a
sociologist listing the mentions of gravitational waves he has seen in the
media. But it has no meat to it, and there is no payoff: it just lists them,
and ends. It's excerpted from the guy's book, but it won't make you want to
buy it.

The only slightly surprising things (I won't go as far as to say
"interesting") are:

1) The Daily Mail and Barack Obama apparently made the same mistake about
Einstein's predictions.

2) Without comment:

> Later I will discover that my major thesis about social construction, which
> turns on pointing out that no gravitational waves were seen but merely a few
> numbers that were interpreted as gravitational waves, has been thoroughly
> anticipated (albeit on a strange, flat-earther YouTube channel that appears
> to treat conspiracy theories as an art form).

~~~
c517402
"1) The Daily Mail and Barack Obama apparently made the same mistake about
Einstein's predictions."

Einstein predicted the phenomena of gravitational waves mentioned by Obama,
but Einstein did not predict the gravitational wave chirp of coalescing black
holes detected by LIGO and mentioned in by The Daily Mail.

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PaulHoule
The US military has had an SBIR out for years to develop a gravitational wave
radio. It could go right through the earth, no need for satellites. The
transmitter though would probably use enough energy to destroy the enemy,
maybe even the whole Earth.

~~~
gus_massa
Do you have a link to support your affirmation?

The gravity waves detector are enormous. To get a good signal, the gravity
waves emitter must be enormous too. I haven't done the calculation, but I
doubt that gravity waves can pass through the Earth. Gravity affect dirt and
it will absorb the waves.

~~~
birdtime
Gravity waves don't "go through" the earth but rather the earth expands and
contracts in space-time. This contracting and expanding of the earth itself,
although minute, is the evidence and detection of gravity waves.

~~~
gus_massa
I know about LIGO, but ...

Can LIGO "see" only upwards or it can "see" downwards too? Neutrinos can pass
though the Earth because they only interact with week force and gravity, and
both have a very small coupling. Can "gravitons" pass though Earth?

As someone noticed in an comment a few months ago, there is no experimental
evidence of the gravitons and no complete theory about them, but I think it's
a good guess.

So, in other words, the minute contracting and expanding of space inside the
Earth while the gravitational waves pass though it must interact with any
particle with mass. The coupling is weak, but there are plenty of them. So
some of the energy of the waves will be dissipated as heat inside the Earth.
How much of the energy of the waves is lost while passing though the Earth?

~~~
gliese1337

      Can "gravitons" pass though Earth?
    

Yes. And the fact that there is no complete theory of gravitons doesn't really
matter. It is sufficient to know that scare-quoted "gravitons" (which may be
real fundamental particles or may simply be mathematically convenient pseudo-
particles corresponding to a classical gravitational wave) can pass through
the Earth.

They must be able to do so, for essentially exactly the same reason that
neutrinos can: they couple extremely weakly to matter. Which should not be a
surprise, because gravity is such a relatively weak force- weaker even than
the eponymous "weak force". The fact that neutrinos couple so weakly to other
matter is also why they are so dang hard to detect. Meanwhile, gravitons /
gravitational waves couple even more weakly to matter, and thus are
correspondingly even harder to detect than neutrinos, and pass through solid
matter even more easily.

Annoyingly, if it were easier to detect them, that would necessarily imply
that the Earth is less transparent to them, and vice-versa: they harder they
are to detect, the more transparent the Earth must be. Because, if the Earth
were not transparent to them, then that entails that there are materials in
the Earth that interact strongly with them, and we could use those materials
to build a better detector!

