
Ultrasound, thermodynamics, and robot overlords (2014) - apsec112
http://independentscience.tumblr.com/post/101728968844/ultrasound-thermodynamics-and-robot-overlords
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titanomachy
> considering all the exceptions that exist for every other set of physical
> laws, thermodynamics has exactly zero exceptions

Actually, conservation of energy doesn't hold on cosmological scales, at least
with the usually accepted meaning of conservation of energy. [0]

That's not relevant to the author's argument, but I think it's dangerous to
perpetuate the idea that thermodynamics is somehow an inviolate theory that
doesn't break down under certain conditions just like every other physical
theory.

[0]:
[http://www.preposterousuniverse.com/blog/2010/02/22/energy-i...](http://www.preposterousuniverse.com/blog/2010/02/22/energy-
is-not-conserved/)

~~~
TeMPOraL
It's interesting that the only theory that seems to be treated as inviolatable
is the one that has big parts built on statistical, aggregate behaviour which
doesn't hold on the small scale.

~~~
KMag
The author of the linked article points out there are competing
interpretations under which mass-energy is still conserved on the small scale.
It's just that if you introduce the variable of local gravitational energy you
wind up with a system of more variables than equations. We don't presently
know of any laws that further constrain the system of equations to a unique
solution unless we take local conservation of energy as an axiom... which of
course prevents us from proving local conservation of energy.

However, we don't have any observations that are inconsistent with local
conservation of energy if gravitational energy is taken into account.

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alkimie2
This really does have a stench of scam and a whiff of foolish VC on it. But
just like cold fusion you hope deep down that it might be possible.

I took a look at the patents which are easily found by searching on google
patents for ubeam as assignee and there just wasn't that much disclosed. Sort
of vague references to steering a beam. It did not appear to be enough to
'enable one skilled in the art to practice the invention.'

[http://www.google.com/patents/US20150214764](http://www.google.com/patents/US20150214764)
(for example)

I did notice one thing: mention is made of capactivie micro-machines
ultrasonic transducers
[https://en.wikipedia.org/wiki/Capacitive_micromachined_ultra...](https://en.wikipedia.org/wiki/Capacitive_micromachined_ultrasonic_transducers)
which seem to be in the same family as the micromachined mirror arrays
commonly used in DLP projectors. My only experience with ultrasonic is with
piezo.

One thing that I learned back then was that ultrasonics -bounce-. Aiming would
be really, really hard. Not to mention that one thing people worry about in
this field of steered array ultrasonics is 'necrosis' (which I don't like the
sound of). Turns out that people use high powered steered beams to peer into
peoples' skulls and to do things to the grey matter:

[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3002099/](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3002099/)

Even assuming arguendo that it would be possible to transmit measurable power
via a steered ultrasonic beam, I certainly don't want to do it anywhere near
my head!

~~~
noir_lord
Yep I'm a layman when it comes to this stuff but everything I've read pretty
much says that a ubeam that functioned correctly would be effectively a short
range ultrasound weapon.

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Confusion
Near perpetual motion machines, near infinite compression schemes, nearly
magical medical solutions: people keep pouring money into stuff that qualified
scientists say is simply not possible. If the majority of people with relevant
expertise say something is not possible, people should just believe them. They
will say more careful things like 'there are technological difficulties' or "I
don't see how you could make that work, but I guess it could be possible" if
there is a possibility something will work.

Years ago the same kind of idea was charging phones by wifi and other EM
radiation ubiquitously available. A short calculation by any physics
undergraduate shows that it is simply impossible. Nevertheless people invested
in companies pursuing the idea. A prototype was presented at expos. The
result: nothing. On the other hand, charging by induction was never said to be
impossible.

~~~
noir_lord
> When a distinguished but elderly scientist states that something is
> possible, he is almost certainly right. When he states that something is
> impossible, he is very probably wrong. - Arthur C Clarke.

However when _all_ the scientists say you are wrong _and_ your device requires
violating the most fundamental theory in Physics then its a different case.

