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Quantum Holography 207
Buzz Skyline writes "Physicists succeed where psychics fail. Researchers from Boston University propose a quantum holography system that can construct 3d images of objects sealed in closed containers. Could it lead to quantum luggage scanners at the airport?"
Schroedinger's Cat (Score:5, Funny)
Nathan
Re:Schroedinger's Cat (Score:3, Insightful)
Re:Schroedinger's Cat (Score:2, Interesting)
Duh
Re:Schroedinger's Cat (Score:1)
Re:Schroedinger's Cat (Score:3)
Re:Schroedinger's Cat (Score:1)
Re:Schroedinger's Cat needs a better box, that's a (Score:2)
Re:Schroedinger's Cat (Score:3, Funny)
Re:Schroedinger's Cat (Score:2, Informative)
Re:Schroedinger's Cat (Score:3, Interesting)
Re:Schroedinger's Cat (Score:2)
Damnit! (Score:5, Informative)
Ask Slashdot: Explain this in English please! (Score:2)
disclaimer: this post really was not intended as a troll or a flame - but if you're going to criticise people for not understanding Heisenberg's Uncertainty Principle, maybe you should help those who don't to do so.
Uncertainty principle (Score:2)
Basically, a quantum particle - like an electron - exists in a somewhat undefined state. Its location and energy are not fixed, but exist more as a set of probabilities. These probabilitiy fields are calculable and are the basis for electron shell level/sublevel 3d models.
The thing that makes all this interesting is that the certainty that a particle's position and energy level can be determined are limited. The more you define one, the fuzzier the other gets. This is not an observational thing, but an intrinsic property, as has been demonstrated by cooling some Cs atoms to
What Schroedinger's cat is all about is the fact that quantum state (the probability cloud) does not collapse until observed. I suppose that means interaction, though Physicists keep calling observation. The cat is representative of some quantum particle in an indeterminate state. It wanders between quantum energy levels until you observe it. Then the quantum state collapses into one of these levels and interacts. This also has been confirmed (the weird travel in between adjacent energy levels) - Some scientists found that they were able to keep a group of atoms from changing energy levels by constantly observing them, whereas another group, which was observed less frequently, did change levels.
Re:Schroedinger's Cat (Score:4, Informative)
Re:Schroedinger's Cat (Score:2)
How decoherence killed schroedringer's cat [nature.com]
Maybe one day we'll be able to figure out how to keep cats in superimposed states, but for the time being Schroedringer's gonna have to decide whether to whack the cat before he closes the lid.
Re:Schroedinger's Cat (Score:3, Funny)
If you place it right, such that the CRT screen is outside the chamber, but the slit-measurement device displays its output only to the cat, then the wave of the electron breaks down iff:
AND
If the cat is dead, the wave should not break down, so the interference pattern should show on the screen. If cats go into a quantum state of being half dead, the interference pattern would always show, otherwise 50% of the time the interference pattern would disappear.
The actual solution is left to the reader.
-- TDR
Re:Schroedinger's Cat (Score:5, Informative)
This is a good question, and there have already been several good answers. However, I don't feel like they've really answered your question.
Far from destroying the uncertainty principal, the article indicates that one of the "spooky" things about quantum holography is, essentially, the exploitation of the uncertainty principle.
Now, as to direct observation and the uncertainty principle: perhaps these should be explained for the casual /.'ers out there.
The uncertainty principle says that we cannot know exactly both the position and momentum at the same time. Momentum is a combination of mass and velocity. Mass often remains constant, so sometimes this is stated as "position and velocity" instead. Now, I used the word "exactly", and I meant just that. We can have a good idea of both numbers, but the more exact one measurement is, the less exact the other measurement will be. Basically, think of it this way: if we take a probe, like the tip of a pencil, and move it around till we find exactly were a particle is, we'll find it. But we'll also hit it and change its momentum.
Now, all observations require some kind of probe, be it pencils, electrons, or photons (light). A related feature of quantum mechanics is that the equations we use to determine where a particle (or wave, they're the same thing at this level) is going (the famous Schrodinger equations) don't actually tell us where a particle is going--only where its likely to go. So we don't even know how to say where it is going to go. In fact, it is considered that a particle does not have just one specific path until the particle has been measured.
In our case, that measurement--that is, the observation of the photons--occurs at the wall of the chamber. And from this data, convoluted equations work backwards to figure out what the photons bounced off of.
Hope that helps...
Probes?! (Score:2)
In quantum mechanics, the momentum distribution of a particle is the Fourier Transform of its position distribution. When the position distribution is narrower, the momentum distribution is wider, and vice versa. This is the basic property of FT. In fact there's a simple counter-argument to the probe effect, because when you hit something with a certain impulse and you know the mass of the particle, you can predict how the hit affects its motion.
[Disclaimer: IAAP]
Re:Probes?! (Score:3, Informative)
Take a
Now zoom in more so only 1/2 a waveform shows. Measure it. calculate the frequency. You now have more accuracy in the timing of the event, but less accuracy of the frequency.
Heisenberg's principle is NOT the confusing thing about physics - it is plain reality! The thing that really is the source of the confusion is that the energy of a particle is related to its frequency - Just like the time and frequency were related in my example.
*IANAP*
--jeff
Re:Probes?! (Score:2)
Zoom in more, so the window is 1 pico second. Great timing accuracy.
But what is the frequency of the single sample? it is a voltage/level now. That information is lost.
position accuracy and frequency accuracy are mutually exclusive.
--jeff
Re:Probes?! (Score:2)
The 'position in time' is more accurate because you have a smaller window. Your 'frequency' is not accurate because you don't see it all.
All you can say is that the frequency is less than or equal to X, where X=1/(window time).
So there is no measurement here. It is not a limitation of measurement devices.
The point is that a particle or photon's energy is related to its frequency. To know this frequency you must take time into consideration. The longer time window you use, the less you know the position.
The photon/particle does not HAVE an instantaneous energy level!
Heisenberg is not the problem, nor is it specific to quantum physics.
--jeff
Re:Schroedinger's Cat (Score:3, Funny)
Meow (Score:3, Funny)
Re:Meow (Score:2, Interesting)
No. At this point, there is no established physical way to "break" the uncertainty principle. I'm not sure why it is not the "uncertainty law" at this point--perhaps this is a subtlety of the way the principal was derived. Nevertheless, it has the tenacity of a law of nature, and will not "break". The equation will not be violated--the uncertainty (or change) in position squared times uncertainty (or change) in momentum squared will alwasy be greater than or equal to Plank's constant divided by 2 (dx^2 * dp^2 >= hbar)
Re:Schroedinger's Cat (Score:2)
The Schroedinger's Cat thought-experiment is totally different.
ANd how does this bother the Cat problem at all? It doesn't.. if you observe the Cat in the box, in any way whatsoever, you have now observed it, and hence, caused it to assume a known state.
Re:Schroedinger's Cat (Score:3, Funny)
Re:Schroedinger's Cat (Score:1)
Schroedinger's Cat: The Secret Revealed! (Score:1)
Re:Schroedinger's Cat (Score:1)
Some info for those that don't know... (Score:3, Informative)
http://users.ox.ac.uk/~jsw/Schroedinger.html
Oops (Score:2)
Re:Schroedinger's Cat (Score:1)
Re:Schroedinger's Cat (Score:2, Redundant)
Re:Schroedinger's Cat (Score:3, Funny)
Re:Schroedinger's Cat (Score:2)
Re:Schroedinger's Cat (Score:3, Funny)
Psychic? (Score:1, Offtopic)
Physicists succeed where psychics fail.
Sure, but can it tell me whether my wife is cheating on me? Or that I will meet a mysterious stranger after a journey of great distance?
Re:Psychic? (Score:1)
No luggage scanning here (Score:5, Insightful)
So unless someone is stupid enough to try and sneak a bomb onto a plane in one of these spheres, it's not much use to the security guards.
Re:No luggage scanning here (Score:3, Funny)
We could always pass a law mandating that all bombs being carried on by terrorists be enclosed in this type of sphere.
And if that didn't work, we could always require that the device be clearly labeled "BOMB". I think a $300 fine should be sufficient penalty for this, don't you? At least it would be if we were talking about corporate violators...
Re:No luggage scanning here (Score:2, Funny)
Re:No luggage scanning here (Score:2, Informative)
Re:No luggage scanning here (Score:2, Interesting)
The specially constructed sphere is the easiest, and thus first, configuration to be tried in the lab.
All they need to do is require all interior luggage surfaces be built from these time-reporting light sensors (and maybe prevent travellers from putting anything else in the bag if they have a bomb), and voila! No time-and-cost-prohibitive bomb-sniffing machinery!
OT Spheres (Score:2)
Reminds me of the old joke...
In the early days of Rocket Science(tm), they were trying to figure out how to protect the astronaut from acceleration. So they hired one of the leading physicists of the day to investigate.
A month later, he came back with a solution. He got up in front of the NASA bigwigs, and said, "First, assume a perfectly spherical astronaut..."
Peering into luggage.. (Score:3, Funny)
Nice ap, but no real world potential yet (Score:1, Redundant)
You can assume what it looks like and then create an image out of that assumption, but unless you are looking directly at it, you'll never know.
Re:Nice ap, but no real world potential yet (Score:2)
Ah, but what if I knew what it looked like before setting the whole thing up? If my hologram looked like the original, as I saw it in the first place, then is this not accurate?
I suppose you could argue collapsing wave functions and quantum probability, but I'd think that was pushing it, no?
More important implmentations (Score:4, Insightful)
No more exploratory surgery. Quickly detect cancer growths.
Re:More important implmentations (Score:5, Funny)
Yeah, I can see it now:
"After putting you in this big sphere and exposing you to massive amounts of electromagnetic radiation, we've determined that you do indeed have skin cancer."
Re:More important implmentations (Score:1)
X - Ray Specs (Score:4, Funny)
Not such a good idea... (Score:1)
Did they charge $4.99 a minute for the call? (Score:1)
only with special holographic-quantum luggage (Score:1)
to detect the time when a photon hits the wall but not where it hits.
this only works with special luggage that can detect when a photon hits its inner lining...
Can't see inside solid objects (Score:1)
Dunno if their idea works... (Score:5, Funny)
Re:Dunno if their idea works... (Score:2)
You can pick only one of the following lists, which you should write down in a checker/chequer pattern on some paper. For each row or column, you score 1 point. The first full-house wins. If nobody gets a full-house, then highest score wins.
Card 1: Digitati, Quantum, Holodeck, Spooks, Jon Katz, DMCA, Conspiracy, Amazing, X-Box
Card 2: Microsoft, IBM, SGI, Red Hat, Oracle, Sun, Nintendo, Gartner Group, Linus Torvalds
Card 3: Broadband, @Home, Wireless, DoS, Viruses, Security, Encryption,
No Technological Obstacles? (Score:1)
Correct me if I'm wrong here, but according to the article this process relies on quantum entanglement. As far as I know this has never been achieved on a large scale - only in single pairs.
As I see it here this would require two lasers to be emitting entangled beams. I've never heard of a way this can be done. Without, as far as I can see, this process would not work. Seems to be a rather large sticking point... though I don't know how many photon pairs they actually need out of those beams. Anyone know more about this?
None the less, the theory is 'spooky' indeed.
Re:No Technological Obstacles? (Score:1)
IANAPhysicist, but...
Doesn't the uncertainty principle and the whole probability function idea of quantum mechanics suggest than a single photon pair would be all you'd need for the whole object? Theoretically, you could superimpose the probabilities of it bouncing off every single surface of the object at once to get the whole thing. The article mentioned that they would measure when the particle hit the sphere, not where, so that measurement wouldn't disrupt anything.
Now how do they extract and superimpose all those probablilities.
Airports? (Score:1, Offtopic)
-Legion
What it's used for? (Score:1)
umm.. If we read the article. (Score:2)
propose to create holographic images of objects concealed in a spherical chamber. Ideally, a small opening in the chamber wall permits light to enter, but lets no light out. The photons in a beam of light directed through the hole scatter from the enclosed object, and ultimately strike the inner wall of the chamber (see figure).
So it's not sealed, but a small opening. I dunno if I want people making holes in my luggage.
What's That?! (Score:3, Funny)
"Sure does look like one..seize her!"
Five minutes later.
"There was no bomb in here..WTF?"
"It would have been in there if we hadn't looked!"
In Airports? I think not... (Score:3, Funny)
I don't believe so. I personally feel the problem with airport security is not the type of equipment used, but the incompetence of some of the security people employed there. You've heard the security breach stories on the news.
"What is that, a hairdryer with a scope on it ?... That looks okay, keep it moving". "Some sort of bowling ball candle ? That's fine, just... we don't want to hold up the line, don't hold up the line"
Jerry Seinfeld on Airport Security
Re:In Airports? I think not... (Score:2)
Luggage detectors of tomorrow (Score:1)
Sure makes repacking a breeze!
Faster than light communication (Score:4, Interesting)
Couldn't you use it to communicate instantly over any amount of distance?
Imagine:
You are at point A (say, earth) and I'm at point C (say, a spacecraft) and we have a buoy, at point B, precisely half way between us. Let's say that you and I are one light-year apart, and that buoy has been splitting a beam of photons between the point where I am and the point were you are for the last six months.
You have a photoreceptor oriented 90 degrees out from the beam, and I have a mirror at 45 degrees, hooked up to a solenoid. I type you a message in morse code on a switch that controls current to the solenoid. You see it in real-time.
I'm sure that either 1. there is a really good reason why this won't work in theory or 2. someone else has proposed it.
Can someone give me a reference either way?
-Peter
Re:Faster than light communication (Score:3, Informative)
The article doesn't make it clear, but the measurement taken in the chamber must, I have to assume, be transmitted and used in constructing that second image (it doesn't just *happen*; you can't shine a beam of light, even entangled photons, and expect them to magically scatter off nothing. When the first entangled beam is measured, quantities of the second half are determined, but that doesn't make them scattered, since it was *possible* they were in that state already... it has to be possible, that's how quantum physics works). It sounds like the information would be used in a second beam interfering with the intangled beam, but I'm not certain from the article... but I can guarantee that information has to be used.
Re: (Score:2)
Re:Faster than light communication (Score:5, Interesting)
No, you couldn't. :-)
Your mirror scenario wouldn't be making any measurements on the incoming photons, I don't see that it has anything to do with entanglement.
Let's look at another example that gets closer to - but turns out not to be - instantaneous communication. It's been a while since I studied this, so real physicists please correct me, but I think I remember the gist of it.
We'll use polarization as an example. Quick review: every photon is polarized at some angle. If it hits a detector that's at the same angle, it passes though; a detector at 90 degrees to its angle, it's blocked; and at some angle in between, it may or may not pass through, but if it does it will now have the new angle of the detector (i.e., a 45 degree photon hitting a 0 degree piece of polarized material has a 50% chance of being blocked at a 50% chance of passing with its polarization at 0 degrees).
The polarization vector is a quantum superposition of the 0 degree and 90 degree states. If two photons are entangled, and one gets measures and "snaps to" one of these states, its entangled partner always "snaps to" the same state. (Or maybe it always snaps to the opposite state. I forget. Doesn't matter for this example.)
Let's say that our entangled photon source is sending out beams that are polarized at 45 degrees (i.e., in a superposition of 0 and 90 degrees). The sender - call her Alice - sets her polarization detector to either 0 degrees (to transmit a "dot") or 90 degrees (to transmit a "dash"), and her photon randomly snaps to one of these polarizations. If it happens to snap to the matching one, it passes thru the polarization detector.
A light-year away, the matching photon in the detector belonging to the receiver (call him Bob) spookily snaps to the same polarization direction. Bob's all set to make a measurement, but which way should be set his polarization detector? If he sets it at 45 degrees, then regardless of whether the photon is at 0 or 90 it has a 50/50 chance of passing through, so he'll see half the photons pass. If he sets it at 0, the incident photon has (from Bob's perspective, not knowing whether the next bit of the message is a "dot" or a "dash") a 50/50 chance of being polarized at 0 at 90 degrees, so he'll see half the photons pass. Same if he sets it at 90.
Even though the photons were linked, and each instantaneously "knew" what was happening with the other one, no information can be recovered from the beam, because what the photons do is still random.
(However, by changing this around a little bit Alice and Bob can generate an unbreakable cryptographic key - search Google for "quantum cryptography".)
Re:Faster than light communication (Score:2)
I have practically no background in quantum physics, but:
Couldn't you, say, devise a system where each "bit" of information was transmitted for a certain length of time? After all, this is basically a serial communication system, so as long as you know the time for a bit, you wouldn't have to know the polarization of every single photon passing through--you could just catch the 0-degree (or 90-degree, either way) photons, and assume that when you weren't getting photons then they were all polarized the other way, giving you a bit of the opposite value.
Or so it seems to my simple mind, anyway... is there a reason this wouldn't work?
Re:Faster than light communication (Score:2)
How? Alice can't reach out and twist that photon. All she can do it rotate her detector, and the photon may or may not - the probability depending on its incident polarization - pass thru and take on the detector's polariztion. That randomness is what makes it impossible to pass information in this way.
Re:Faster than light communication (Score:2, Interesting)
David
P.S. Of course, I could be wrong. Any quantum physicist out there wish to confirm this. I'm sure this is what they did in the Bell experiment.
Re:Faster than light communication (Score:3, Informative)
It's more correct to say that if one entangled particle changes, the other changes too. But that only helps you do instantaneous communication if you can change an entangled particle in exactly the way you want. No one's figured out how to do that.
As far as we can tell at present, quantum nonlocality and "spooky action at a distace" exist, but cannot be made to transmit any information.
Looking at a paper I did about ten years ago, I found the following quote from Nick Herbert's Faster Than Light that summarizes the situation:
Yes and No (Score:2, Interesting)
The idea is that since photons travel at the speed of light (duh), they don't experience "time", and can actually make a "choice" about the path they are going to take, so that an entangled pair of photons "agree" as to where they will be in the future. This has the affect of looking to us like there is an "instantaneous transmission" of information from one to the other, which would violate causality from the standard view. The "choice" is the ability of the photon to "feel out" all the possible paths it could take, and select an event in the future to which to tie itself to. This might be interpreted as a basis for "fate", which is fine by me, since that's the way I lean anyhow.
Obviously (as IANAP) this explanation is worded poorly and not really an accurate representation of the weird math involved. But, while information is "traveling back in time", I don't think there is a practical way to use this effect as a communications medium. Maybe you could have four entangled beams (two each for two observers)?
Re:Faster than light communication (Score:2, Informative)
This concept was originally conceived sometime around 1930 by einstein, podolsky, and rosen as an argument intended to torpedo quantum mechanics.
basically they pointed out that quantum mechanics predicts that if you prepared a four state quantum mechanical system (ie 2 qubits) in a certain way (creating an EPR pair) they would exhibit "spooky action at a distance". at the time it was a fundamental principle that cause and effect had to obey the speed of light and therefore quantum mechanics was broken.
turns out there is massive amounts of evidance that cause and effect can be instantaneous over any distance and quantum mechanics goes on to be the most succesful scientific theory in history.
the scenario is this: alice and bob create an EPR pair, and then each takes one to opposite ends of the universe. when alice measures the state of her qubit, bob's qubit instantly becomes a known quantity.
it has been proven that to use this effect for communication requires the communication of classical bits of information (i believe it is the result of alice's measurement) which are governed by the speed of light. hence quantum entanglement can not be used as a truly instant messaging transport.
however, you can use this effect to achieve perfectly secure cryptographic key distribution and this has actually been done several times.
quantum computing is super cool and might actually be practical. check out http://www.qubit.org for some well chosen tutorial papers and links.
More impressive than 3d (Score:2)
What is really impressive is that they can see what the surface of a flat object, like a photograph, looks like. Neat!
-Peter
The True Effects of Quantum Computers (Score:2, Informative)
Quantum computation, however, is much more complex and much more interesting. Quantum computers are based on the concept of quantum entanglement, the ability of a quantum state to exist in a superposition of all of its mutually exclusive states: It's a 1 and a 0. However, this is not as easy to use as one might think. While it's true that if you have n quantum logic gates you have the ability to input 2^n data values simultaneously (as opposed to only 1 piece of data if you have n digital logic gates), this is not going to be the end of classical computing for a few reasons. First, quantum computers have to be perfectly reversible. That means for every output there's an input and vice versa. And there has to be no way of knowing the initial states of the data. You don't process data, you process probabilities in a quantum computer; if you know exactly what any one value is throughout the computation, you can find out all of the values: the superposition ends and you're stuck with a useless chunk of machinery. This means YOU CAN ONLY GET ONE RESULT FROM ANY QUANTUM COMPUTATION, THE END RESULT. You can't see what the data in the middle is or the computer becomes useless. (Landauer's principle makes heat loss data loss. When your processor gets hot, it's losing data. If the same thing happened to a quantum computer, it wouldn't be quantum anymore.) Decoherence is what happens when you randomly lose data to the environment by design, not by choice, and the superposition ends. This is bad for Q.C. Oh, and quantum computers can only do *some* things faster, like prime factorization and discrete logarithms. Not multiplication or addition. Plus, the circuits that would do basic arithmetic would be bigger and slower than what you've currently got.
So what does this all mean? It means that quantum computers are going to provide some advantages (real quick big number factorization), and some disadvantages (that whole RSA standard). The most realistic initial use of quantum computers will be as add-ons to existing super-computers to resolve certain types of NP-Complete headaches that regular math can't simplify yet. At best they will someday be an add-on to your PC; but they will never replace the digital computer.~
If you want more info, check out ahttp://www.qubit.org, it's got some decent tutorials.
Does this allow... (Score:2, Funny)
...a new, more efficient porn acquiring method for geeks - because most clothes are not entirely opaque and some light gets to the skin, can this be used to acquire 3D nude holograms of fascinating females that pass by?
Re:Does this allow... (Score:2, Funny)
Think of the porn! (Score:2)
Link to the real thing. (Score:4, Informative)
actual paper itself. It's a PDF file though
Hologram of a suitcase :-/ (Score:3, Funny)
... a hologram of a suitcase! Methinks this one will need work before it replaces the good ol' Airport Xray machine.
Of course quantum entanglement is also how "they" propose to achieve the matter-transporter, so forget looking inside the luggage, we can just send it on ahead
Re:Hologram of a suitcase :-/ (Score:3, Funny)
Ah yes, the most-often overlooked of stringed instruments! Mind you, I like a nice cello, myself.
The real significance: (Score:2)
This is about exploring quantum entanglement. When lasers were invented, nobody knew what to do with them. Everybody thought "Death ray!" which was pretty silly in retrospect; that's a minor application. Then, bit by bit, they found thousands of ways to apply them that revolutionized all sorts of practical devices and allowed entirely new ones.
Developing this would be breaking old rules about what is and isn't possible, and though it's hard to guess exactly what it's good for, you can bet it'll be good for some amazing new technologies.
background information about holography (Score:4, Informative)
Holography basics (aimed at Highschool students level). [cmaisonneuve.qc.ca]
Books and information on Holography [rossbooks.com]
Some more holography Theory> [hologram.net]
Take a closer look (Score:3, Insightful)
-theres no X-Ray vision here! For luggage they would be able to say "I think its a suitcase"
-it does seem "spooky" though
-it does have potential uses that could be really cool. Remote surgery, biometrics, 3D video
Photosensitive Sphincter: anyone read the article? (Score:3, Funny)
The technology described will not scan your luggage, nor will it make body cavity searches obsolete, unless you have a spherical, photosensitive rectum.
Not a cure for cancer, or a replacement for a cat scan or MRI.
What the technology excels at is showing you what's inside a specially constructed sphere. This information could also be garnered with a sufficiently large hammer.
A cool physics party trick, and some interesting basic research. That's about it.
Not entirely new... (Score:3, Interesting)
The object has to be at the bottom of a pool filled with some opaque liquid; a transducer is immersed, bathing the object with ultrasound. Sound waves reflect on the object, and they form an interference pattern on the surface, which is lit by coherent light, thus forming a virtual image of the object.
One caveat, though... Given the ***BIG*** difference of wavelength, the virtual image appears to be quite far, and has to be viewed with a telescope...
Been There, Done That (Score:2)
http://www.exploratoriumstore.com/miragemaker.h
Original article (Score:4, Informative)
Abouraddy,A., Saleh,B., Sergienko,A., and Teich,M. Quantum holography [opticsexpress.org] (PDF, 169KB, 8pages), Optics Express, 9, 498-505 (2001).
Read the damn thing (if you can :-)), then discuss.
Atomic Laser? (Physicist help pls) (Score:2)
With an atomic laser it is theorized that you can create a matter hologram, whatever that is, supposedly just like the original.
Wonder if it hangs around after you turn off the reference beam? It would be a bitch if you lost the original.. poof!
Important applications in microscopy research (Score:2, Insightful)
Re:Quantum Holography (Score:1)
Re:Quantum Holography (Score:1)
If one has to actually first put the object into the sphere, then one (obviously) already has a quite good apprehension
what it looks like...
unless one wants to "see" something that was "created" while in the sphere...?
Got to love a Troll! (Score:1)
Please mod it as a troll.
Re:This could be used to fight terrorism (Score:1)
Shoplifting has NOT been stopped dead in its tracks, and certainly not because of security cameras. In fact, shoplifting is still vastly more common than terroism, despite the fact that it is an enemy that we CAN see.
Re:This could be used to fight terrorism (Score:2, Interesting)
Think for a moment which is worse: to have the government searching you in broad daylight, where everyone can witness, or to give that government the power to search you at any time it wishes, with neither consent nor notification?
I for one do not feel the same way. In my mind, this kind of "secret" searching is just as degrading, and does not provide as much protection for the citizen.
Re:This is crazy (Score:3, Insightful)
This can still be performed if, for example, bits A and B are on different HDs, and I ship one across the country. Suddenly, by reading one, I can tell someone across the country what they will read at the address where their bit is on the disk.