h a l f b a k e r y
Clearly this is a metaphor for something.
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What magic nonsense is this you say?
Well, we all know the two slit experiment, and its more
bizarre quantum cousins. As the theory goes, a given
particle can be anywhere in the universe, spread across
probability function. That quantum probability, for
instance, is what allows black
holes to radiate out
that they couldn't radiate under classical relativity. This
effect is known as Hawking Radiation.
Assuming quantum theory bears some relationship to
reality, this would mean that if you could build a
or particle detector, that filters out all ambient traffic,
captures ONLY those particles or photons that
in a quantum fashion (i.e. not having traveled through
every point from A to B), and in a further assumption,
one could know what the A for a given particle was, and
filter on such source information as well, one could look
any spot in the spacetime continuum, in real time.
How would one detect particles that have not gone
every point from A to B?
Well, perhaps here we take a lesson from the recent
explosion in extra-solar planet detection -- who would
thought, after all, that detecting the wobble of a planet's
gravitational pull, or the slight dimming due to a transit,
would be possible -- and yet it is.
In a similar way, perhaps one could use a star that is
known to be on a given arc "today", but is visible in a
different arc since light from it is taking so many light
years to arrive here. Looking for its telltale signature
photons in areas of the sky which are not aligned to the
star might yield the occasional photon that
rather than traveled the distance.
Clearly this, discerning the data that teleports in rather
than travels the distance, is the challenging part of
building the device. But perhaps even better techniques
based on energy levels or other criteria can be devised.
[theircompetitor, Mar 25 2014]
The McGuire Effect
A classic quantum paradox [8th of 7, Mar 26 2014]
Information not destroyed
[theircompetitor, Mar 31 2014]
||I don't know enough to figure out why this is wrong.
||exactly, that's why I found it so interesting :)
||//How would one detect particles that have not
gone through every point from A to B?//
||You can't. By definition.
||// Looking for its telltale signature photons in
areas of the sky which are not aligned to the star
might yield the occasional photon that
"materialized", rather than traveled the
||You have no way of knowing if that photon is from
the star who's current location you are pointing
at, or the one next to it, or the one right behind
you and three doors to the left. Or, for that
matter, spontaneously coming into existence in
front of your telescope, with no actual source.
||//I don't know enough to figure out why this is
||Expound on "no way", [MechE]. I would
it is hard :)
||For instance, the linked article talks about fairly
obscure ways to prove that radiation is, or is not,
Hawking. That in that case, the photon shows up
outside the blackhole, and not inside it, is in itself
some sort of evidence that it came from within,
||BTW, if we get some REALLY serious
computational power, one could for patterns in
the noise. For instance, let's say I wanted to look
at a star map as it would look 1,000 years from now
-- which I can compute. I then look at only the
photons that "validate" that map. Kind of like the
bible code of photons.
||Before this gets any further, I'd just like to make the
confident assertion that all the relevant issues will
be resolved within the next 2-3 annotations.
||well, I have no expectations, not even for an
[ignoble], [MB] :) But I just was struck by the fact
that this is a bizarre possibility which I have not
heard discussed before
||Because an individual photon is not characteristic
of a given star. A spectrum of them is, but if this
works at all, you are going to receive photons
from indefinitely many stars, with no particular
probability advantage that any given photon is
from your target star. The fact that your scope is
pointed in a certain direction doesn't help, since if
the position of photons is truly only determined
by probability, then there is essentially the same
chance that your scattered photon is coming from
a star behind your scope.
||A spectrum would certainly increase
computational requirements. But, if one energy
level photon would arrive by accident, surely there
are cases where N do.
||But I think the "validating starmap" case is more
interesting. You know how the starmap will look
like to some excent. Can you in fact find in the
noise that same star map.
||//Assuming quantum theory bears some
relationship to reality, this would mean that if you
could build a telescope, or particle detector, that
filters out all ambient traffic, and captures ONLY
those particles or photons that materialized in a
quantum fashion (i.e. not having traveled through
every point from A to B)//
||Here's where you start to go wonky. Quantum
indeterminacy drops off exponentially with
distance; it never quite goes to zero, true, but
becomes almost absolutely undetectable beyond
nanometer scales. On light-year scales? You would
have to wait a very, very long time for even a single
photon from Alpha Centauri to arrive at your
detector through uncertainty as opposed to the
normal fashion. I don't have the relevant figures in
front of me, but I'd wager that the probability is so
low that by the time a single photon jumped the gap
to your detector, the Sun would already have
expanded to burn it up.
||//But, if one energy level photon would arrive by
accident, surely there are cases where N do.//
||But it's equally likely that you get N1 photons from
star A, N2 photons from star B, N3 photons from star
C, and so on and so forth. Without any way of
already knowing which photons are from which star,
the simple arrival of photons does not provide any
||Also, keep in mind that you're not just getting
photons from star A that jumped the N-light-year
gap - you're also getting a lot more year-old
photons from A that traveled a bit and jumped the
N-minus-1 light-year gap, and even more two-year-
old photons, and even MORE three-year-old
photons, and exactly as many that are actually
older because they jumped the same distance away
from you instead of towards you...
||It would be absolutely impossible to extract any
kind of past star-map from such a "signal".
||Especially since such a signal would be so utterly
miniscule that the far more common picometer-
scale quantum jiggling of atoms and electrons in
your detector would drown it out entirely.
||(My phone has an unusual anomaly where blocks
of text will vary wildly in size from paragraph to
paragraph. It makes the site look like a
monochrome rendition of Time Cube. Great to have
the site back, though. One of the few sites from my
childhood that still maintains activity and
||[Hive Mind] -- so look, that's all good, and my
biggest claim to Physics fame was taking a few
classes with Dr. Kaku :)
||But no doubt we could have had a similar
discussion about the transit or wobble planet
discovery methods. I understand the haystack is
bigger and needle is smaller. Nor am I expecting
such a device to be built anytime soon. But I
haven't heard yet why it's impossible. Look at the
lengths they're going to for discovering WIMPs, not
to mention the LHC.
||I'm not quite sure you understand the needle-to-
haystack ratio here. This is looking for a needle, in a
haystack filled and indeed made out of largely
identical needles, and also the haystack dwarfs the
Local Group in size relative to a standard needle.
||I knew someone would bring the Local Group in at
some point :)
||I'll take that and I'll add quantum computing.
||No, because the wobble or transit methods don't
require information be transmitted faster than the
speed of light.
||as does Hawking Radiation
||One piece of photographic paper (assuming it's still being made), one neutrino detector, one very thick lead box.
||Put items in box. Leave for some time. Develop film, then presumably by excluding the number of neutrino hits, you now have some idea of how many photons quantumly turned up.
||I'd suggest running that data through a 3d printer, then doing a rubbing of it and then take it to a science fair and say "Hey everyone, here's my rubbing of the star Arcturus".
||Well, they might be from Arcturus.
||Time viewing eh, does this idea have hair? If it is Hawking radiation and this particle and its pair are created from pure energy why would it contain any previous information?
||//as does Hawking Radiation//
||No, it doesn't. Hawking radiation requires (in one
interpretation) that an object travels faster than
light (but there are multiple other interpretations),
it does not require information to travel faster than
light. In fact, Hawking's formulation specifically
||Again, unless you can explain how you can tell
whether a given photon comes from a particular
star, reality is absolutely consistent with that
||Pity in his earlier years he did not change his name to "Penguin" or "Zero Point".
||// discerning the data that teleports in rather
than travels the distance, is the challenging
part of building the device. //
||Made more difficult by the so-called McGuire
||I am by no means certain that such photon
properties are discernible, but I've only been
thinking about it for a few hours, and I'm not a
physicist :) The "future starmap" idea is one that
has potential. Another idea maybe to look for
shifted background radiation (i.e. one that comes
from all direction, just as one would expect from
the big bang, but clearly took a different amount
of time to get here)
|| Just as in the experiments that attempt to verify
Hawking radiation itself, there may be a way, it
maybe a very difficult way, or nearly an impossible
way. But I am not convinced it is impossible.
||Maybe I have a suitable explanation here. First,
the particles that appear via Hawking radiation are
IDENTICAL to ordinary particles, and this alone will
make it difficult to determine their origin.
||The "quantum foam", or "energy fluctuations in
the vacuum", or "virtual particles" of QM consists
of ordinary particles popping into existence
temporarily, usually in pairs, and vanishing again,
also in pairs. When they INITIALLY appear, they
can possess any velocity up to nearly light-speed.
||AT the event horizon of a black hole, the escape
velocity is exactly light-speed. JUST outside the
event horizon, the escape velocity can be such
that a just-popped virtual particle might have
enough velocity to escape the gravitational field
of the black hole.
||So, according to Stephen Hawking, one particle of
a virtual pair gets swallowed by the black hole,
which prevents them from being able to get-back-
together to vanish again. The other particle is
allowed to become a "real" non-virtual type of
particle, as a result, and the energy for its long-
term existence is subtracted from the mass of the
||This newly-real particle, IF it happens to be
travelling in the correct direction, can now escape
the gravitational field of the black hole.
Otherwise it will eventually be swallowed, too,
and the overall mass of the black hole won't be
affected (in terms of "before" the pair of virtual
particles appeared, and "after" the second gets
||If the newly-real particle actually escapes the black
hole, remember it will do so by climbing out of a
very deep gravitational field. Its velocity, when it
finally gets away, might be only a centimeter per
second, or even less. (If the particle was a
photon, it will still be traveling at light-speed, but
its energy content is going to be sucked super-
low. More on this in a bit)
||Now imagine this black hole being located 100
light-years from Earth. How long is it going to take
a non-photon particle to travel here from there,
travelling a centimeter per second or less?
And how do you expect to identify it from all
those other particles speeding along (cosmic rays)?
What about interactions of that particle with
others, in all the ages of time that will pass as it
travels toward us from its origin?
||So, I have no expectation of being able to detect
ordinary-type particles that might escape a black
hole. We might be able to detect those super-
low-energy photons mentioned above, but I
suspect we currently don't have a radio telescope
big enough to do that job (not to mention that
the Earth's ionosphere tends to reflect low-energy
photons; the radio telescope may need to be
off-Earth). This is where my
understanding of the overall situation comes up
short, not knowing just how low-energy those
photons will be.
||[MechE] duh, the answer is, do it in a very dark
room. Use one of the WIMP experiments, see if you
get photons over a meaningful exposure time, then
see if generated map maids out to anything
||Feel free to try. Please don't apply for any
government grants, as I don't want my tax dollars
at work on something that doesn't.
||The entire basis of this idea is that you are
tracking photons that "tunneled" from the target
star. But, depending on distance, you are equally
or more likely to receive photons that "tunneled"
from stars that your scope is not pointing at. The
important point here is that the vector of
"tunneling" is completely separate from the vector
of the photon itself. Therefore, you are as likely
to receive a tunneled photon from a light bulb
behind you as in front of you.
||Aha, so you are worried I might actually get a grant!
||Given who's actually on the congressional science
committees, yes, I'm worried you might get a grant.
I'm also worried that feng shui practitioners,
dowsers, and perpetual motion inventors might get a
grant. Unfortunately it does not seem to be the
case that scientific literacy is a requirement for
deciding who gets money.
||[Vernon] My understanding is that there are
alternate, mathematically equivalent, explanations
for the effect, that aren't based on the "virtual
particle" thing, but I'm not clear on them. That's why
I haven't resorted to that argument, because I'm not
certain enough to discuss it.
||// I'm also worried that feng shui practitioners,
dowsers, and perpetual motion inventors might get a
grant// Well that's just mighty uncharitable. I'm
doing this in the spirit of the HB, and I think it's a
somewhat fun proposal that I've never heard before,
with obvious issues. You are treating it as a
humorless peer reviewer.
||Yes, that's what I do here.
||I will discuss nonsensical ideas as such without a
problem, but a serious idea with a fatal flaw in its
physics will get that flaw pointed out.
||//a fatal flaw in it's physics will get that flaw pointed out //
||What if it has a fatal flaw in it's grammar ... ?
||Wasn't this already halfbaked by Douglas Adams, using a small piece of cake as the detector?
||//What if it has a fatal flaw in it's grammar ...
||"What if it has a fatal flaw in it"'s grammar looks fine to me, other than the missing punctuation.
" I don't know enough to figure out why this is wrong "