
Gravity's Most Extreme Effects Can Now Be Tested In A Laboratory - randomname2
http://www.forbes.com/sites/startswithabang/2015/11/12/gravitys-most-extreme-effects-can-now-be-tested-in-a-laboratory/
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genug
120 years ago, people thought that experimental results on wave propagation in
continuous media could be used to make statements about wave propagation in
electrodynamics. That's how we ended up with ether theories, which were
eventually falsified with interferometric experiments.

To my mind, we should take this as a lesson that the notion of analogue
systems (e.g., using results from fluid dynamics to make statements about
gravitation) is bogus. The ether episode seems to indicate that if we want to
make statements about gravitational Hawking radiation, we need to do tests on
a system where the gravitational dynamics are important (e.g., a black hole),
not an unrelated system that just happens to be governed by an identical set
of equations in some regime.

Another example of people incorrectly conflating properties of an analogue
system with the real system of interest is the Nature monopole paper:
[http://www.nature.com/nature/journal/v505/n7485/full/nature1...](http://www.nature.com/nature/journal/v505/n7485/full/nature12954.html)
The actual result contained in the paper is that you can make a BEC whose
vorticity field has regions of nonzero divergence. It is mathematically
similar to (but fundamentally unrelated to) actual magnetic monopoles.
Nonetheless, the paper contains the phrase "Dirac monopoles" in the title and
then spends half the abstract talking about actual magnetic monopoles, as if
the result is somehow relevant to actual magnetic monopole searches (which it
isn't).

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Ono-Sendai
All ether theories weren't really falsified, just discarded on a metaphysical
basis as being redundant.

~~~
CamperBob2
I wouldn't say that. The Michelson-Morley experiment demonstrated that if
there _was_ a luminiferous ether, it had no measurable inertia. That pretty
much falsified the ether as anything that we'd recognize as "real."

~~~
Ono-Sendai
I've never read about the ether needing to have inertia.

Also, a modern version of the ether is pretty well accepted - quantum fields
that occupy all of space. Particles etc.. are disturbances in this field.
Ether is something of a tainted term these days so quantum fields are not
referred to as ether.

~~~
chc
Quantum field theory doesn't seem very much like the luminiferous ether. This
seems like finding a new species of grasshopper that lives on a mountain, and
saying, "Ah-ha, I've found Zeus! Zeus is a thing that lives on a mountain and
has never been seen before, so this must be Zeus!"

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dave_sullivan
I keep running into sonoluminescence lately
([https://en.wikipedia.org/wiki/Sonoluminescence](https://en.wikipedia.org/wiki/Sonoluminescence)),
this kind of reminds me of that? Sonoluminescence reminds me of gravitational
collapse, but I think that's probably because I need to read up more...

Very interesting stuff going on with applied physics though--the most
immediate application is probably materials science (and hopefully better
computers/information processing devices). "Simulating the universe better"
may come to be linked with better general information processing systems too,
as in discoveries in one helps the other. For instance, more work along these
lines: [http://arxiv.org/abs/1510.03776](http://arxiv.org/abs/1510.03776)

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rubidium
I recall reading the first experimental paper on analog gravitational black
holes being created using bose einstein
condensates([http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.105...](http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.105.240401)),
and was happy to see the work continuing here (see referenced paper in the
article: [http://arxiv.org/abs/1510.00621](http://arxiv.org/abs/1510.00621)).

What was very surprising was that it was a single author paper (only the prof
of the group). These sort of research efforts are usually Prof+possible
postdoc+a few grad students. Not sure if prof is leaving grad students out (I
hope not!), or is toiling alone at this work.

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mrfusion
Couldthis be useful for testing the emdrive? I heard one theory is it might be
emitting gravity waves.

