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Particle-Wave Duality Demonstrated With Largest Molecules Yet

Soulskill posted about 2 years ago | from the working-their-way-up-to-cat-sized-objects dept.

Science 107

An anonymous reader tips news that researchers have successfully demonstrated particle-wave duality in molecules that have masses of 514 and 1,298 atomic mass units. The academic paper can be found in Nature Nanotechnology. "Thomas Juffmann et al. fired molecules composed of over 100 atoms at a barrier with openings designed to minimize molecular interactions, and observed the build-up of an interference pattern. The experiment approaches the regime where macroscopic and quantum physics overlap, offering a possible way to study the transition that has frustrated many scientists for decades. ... The relatively large phthalocyanine (C32H18N8) and derivative molecules (C48H26F24N8O8) have more mass than anything in which quantum interference has previously been observed. To have wavelengths that are relatively large compared to their sizes, the molecules need to move very slowly. Juffmann et al. achieved this by directing a blue diode laser onto a very thin film of molecules in a vacuum chamber, effectively boiling off individual molecules directly under the beam while leaving the rest unaffected. ... The researchers observed the particle nature of the molecules in the form of individual light spots appearing singly in the fluorescent detector as they arrived. But, over time, these spots formed an interference pattern due to the molecules' wavelike character.'"

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107 comments

Has it actually been tested on cats? (3, Funny)

Anonymous Coward | about 2 years ago | (#39493513)

Well, has it? You can't say cats wouldn't exhibit the particle wave duality until you actually try it.

Re:Has it actually been tested on cats? (5, Funny)

Anonymous Coward | about 2 years ago | (#39493643)

Yes and no.

Re:Has it actually been tested on cats? (0)

Anonymous Coward | about 2 years ago | (#39494443)

We did as children, the young physicists that we were. We threw cats from the 10th floor to see if their blood spatter would exhibit interference patterns. We were going to write a paper on this, but then first grade and stuff came, and we never quite came around to it. Sigh, good times...

Re:Has it actually been tested on cats? (1)

blueg3 (192743) | about 2 years ago | (#39496165)

Funny, but I'll answer anyway. :-) No, of course it hasn't. Yes, you could say that it exhibits particle-wave duality without trying it. Regardless, Schroedinger's Cat is about superposition of states and not particle-wave duality.

Re:Has it actually been tested on cats? (1)

BasilBrush (643681) | about 2 years ago | (#39496869)

I have a feeling if you herd cats uphill they might exhibit particle-wave duality.

Is there any volunteer? (0)

rush,overlord,rush! (1995452) | about 2 years ago | (#39493557)

I plan to do another experiment: if you keep running into a wall, there will be a probability that you pass through the wall. Any volunteer?

Re:Is there any volunteer? (5, Informative)

semi-extrinsic (1997002) | about 2 years ago | (#39493965)

Scientists are currently trying [sciencemag.org], albeit with somewhat smaller objects than a person. What you should understand is that the tunneling probability is exponentially damped in both the width of the barrier and the size of the object.

Already for a hydrogen nucleus tunneling through the (electrostatic) potential barrier presented by another hydrogen nucleus, the probability is around 10^-30 (if memory serves correctly). This fact is what keeps the sun burning for billions of years, and not exploding like a hydrogen bomb in a split second, since it limits the rate of fusion processes in the sun.

Re:Is there any volunteer? (3, Insightful)

Samurai Tony (1202095) | about 2 years ago | (#39494439)

I think you'll find that the sun is, in fact, exploding exactly like a hydrogen bomb.

Re:Is there any volunteer? (5, Informative)

semi-extrinsic (1997002) | about 2 years ago | (#39495399)

Alright, let me clarify what I meant. In fusion, the main factors in determining the reaction speed is the energy and the density. While the energy is comparable in the sun and a hydrogen bomb, the density is 2 orders of magnitude higher in a hydrogen bomb than at the sun's core. The tunneling probability is exponentially sensitive to the density; so sensitive that a third of the way out from the sun's core, fusion can no longer happen. This means that those 2 orders of magnitude are translated into 20 orders of magnitude slower explosion. At that point, I wouldn't call it an explosion.

Just to highlight this point: the power production per volume at the sun's core is 280 W/m^3. This is less than for a human being, it's roughly the same power as a crocodile produces per volume.

TL;DR: You're saying that the smoldering pile of flour on my kitchen bench is exactly like a dust explosion. I beg to differ.

Re:Is there any volunteer? (2)

Tanktalus (794810) | about 2 years ago | (#39495767)

TL;DR: You're saying that the smoldering pile of flour on my kitchen bench is exactly like a dust explosion. I beg to differ.

With sufficient psychedelics, watching grass grow is exactly like an explosion.

Re:Is there any volunteer? (1)

blueg3 (192743) | about 2 years ago | (#39496215)

I should point out that for sufficiently small objects, scientists already do this on a regular basis. Scanning tunneling microscopy, for example, relies on electrons tunneling through a potential barrier, using the tunneling rate to measure the strength of the barrier. (Strictly speaking, small-scale electron tunneling is happening all the time, everywhere, but that doesn't make for a good concrete example.)

Movie (4, Informative)

buchner.johannes (1139593) | about 2 years ago | (#39493569)

The mentioned researchers in Vienna [quantumnano.at] created this movie where you see both the particle nature as well as the interference pattern:

https://www.youtube.com/watch?v=vCiOMQIRU7I [youtube.com]

Re:Movie (0)

Anonymous Coward | about 2 years ago | (#39494877)

Fascinating, but could it be that the atoms in the barrier, put some "spin" (as in cricket or baseball) onto the molecules, forcing them into that pattern?

DNA is large (1)

G3ckoG33k (647276) | about 2 years ago | (#39493589)

DNA is large. Hasn't it been tested?

Re:DNA is large (3, Informative)

Guppy06 (410832) | about 2 years ago | (#39493925)

DNA is a polymer, orders of magnitudes bigger than the molecules they're talking about

Re:DNA is large (2)

Greyfox (87712) | about 2 years ago | (#39494119)

Oh come on! Pass up a chance to shoot something with a laser? What has become of you, Slashdot? What... has... become... of... you?

Re:DNA is large (1)

Anonymous Coward | about 2 years ago | (#39494535)

I thought it had already been demonstrated with individual amoebas fired through a diffraction grating. Of course they don't hold together, but their "guts" were distributed as a diffraction pattern.

Re:DNA is large (2)

feedayeen (1322473) | about 2 years ago | (#39493935)

DNA is large. Hasn't it been tested?

In theory, you could do it with an entire chromosome since these have bonds connecting the entire structure in some way, but the problem is that the wavelength is proportional to it's mass and for something like a chromosome, you're dealing with something with an atomic mass on the order of billions of AMU. This isn't really too big of a problem, the issue comes from that larger molecules have other interactions that interfere with the measurement. A segment of DNA for instance consists of the deoxyribose double helix and base pairs... every single molecule in this chain is going to have it's own signature and not only that, but the atoms too. Getting though all of that noise will be hard.

Re:DNA is large (4, Informative)

reverseengineer (580922) | about 2 years ago | (#39494179)

It would be very difficult to test DNA in the manner described in the paper- it would appear that the specific molecules chosen have a number of attributes that make them suitable for the double-slit experiment. They are fluorescent dyes, which makes them very sensitive to detection, they can be vaporized without thermal decomposition, they are neutral molecules, and they have multiple symmetries so that there isn't a preferred orientation. DNA molecules would be destroyed by the heat sources they used, and the highly charged DNA molecule is likely to interact with the atoms of the diffraction grating in a classical electrostatic manner. Some other biomolecules might be more suitable- phthalocyanine is similar in structure to heme and chlorophyll.

Re:DNA is large (1)

Thud457 (234763) | about 2 years ago | (#39496005)

The quantum evolution folks claim that such an experiment has successfully been done. But then, they're regarded as a bunch of cranks.

They're ignoring quantum laws!!! (1)

sheddd (592499) | about 2 years ago | (#39493603)

Sure, they've measured this very exactly; due to that they can only say those measurements were true at some time between now and +/- 9e99 petabillenia.

Holy Hell that's large (3)

Khyber (864651) | about 2 years ago | (#39493691)

Imagine, we previously thought this only happened with quantum particles, such as photons. This is being demonstrated on MUCH larger (relatively) scales, on a molecular level.

This is mind-blowing. Not only does it not have to be in the EM spectrum, but it can be done with (again, relatively) massive particles.

Re:Holy Hell that's large (0)

Anonymous Coward | about 2 years ago | (#39493847)

When you say previously I presume you mean decades ago, what you are seeing here is not novel, it's just an incremental step, we were doing this with C60 molecules 3 years ago.

Re:Holy Hell that's large (1)

DMiax (915735) | about 2 years ago | (#39494269)

I believe the difference from the fullerene is that they are detecting the single particles here, instead of a stream. In this sense they can really show that each particle interferes with itself, since while one molecule travels to the screen there is no other particle to interact or interfere with.

Re:Holy Hell that's large (4, Insightful)

Anonymous Coward | about 2 years ago | (#39494135)

This should happen with everything, it just happens to be that larger objects are going to very difficult to isolate from noise (which causes "decoherence"). What is impressive about this experiment is the degree to which the experimentalists were able to isolate this system from external interference (and move them so slowly), not that larger objects happen to exhibit QM properties (this is completely expected).

Re:Holy Hell that's large (0)

Anonymous Coward | about 2 years ago | (#39499019)

Ah, but there is an incredible difference between 'expected' and 'observed'. Plenty of theories have 'expected' things that have not been observed, or have been found to not occur. The observation of expected results in a previously untested mode, is definitely interesting as it reinforces the theory, or at the very least expands the known bounds of its correctness*.

* For clarification, Universal Gravitation is not a correct theory, it has been supplanted by relativity, however, it is 'correct enough' under many circumstances.

Re:Holy Hell that's large (4, Informative)

DMiax (915735) | about 2 years ago | (#39494259)

Maybe you thought that.

Among the last few generations of physicists it is generally believed that everything is quantum from an elementary particle to whole planets. It's just very difficult to cool planets down to where the thermal length is smaller than their de Broglie's length. Not to mention creating a coherent planet gun and detector... But there was no reason to believe it is fundamentally impossible.

Re:Holy Hell that's large (0)

Anonymous Coward | about 2 years ago | (#39494593)

Nope. Nobody thought that. Indeed if we thought there was some limit it would make the experiment pointless.

Is it that mind blowing? (1)

DuncUK (2433370) | about 2 years ago | (#39494813)

Wave particle duality had already been demonstrated on Buckyballs which have a collective molar mass of 720. Here's an article is from 1999 : http://physicsworld.com/cws/article/news/2952 [physicsworld.com] OK, these are larger molecules rather than the larger particles in the new research, but what's being presented here isn't so much of a leap... is it?

Re:Is it that mind blowing? (1)

Khyber (864651) | about 2 years ago | (#39494965)

This is being done with molecules made with more than one type of atom, not just pure-carbon buckyballs. That's the other part that got me.

Re:Holy Hell that's large (0)

Anonymous Coward | about 2 years ago | (#39495141)

This is being demonstrated on MUCH larger (relatively) scales, on a molecular level.

So, how big do the test objects have to be before this is finally declared as turbulence?

Re:Holy Hell that's large (1)

Kompressor (595513) | about 2 years ago | (#39498691)

It's hard to be "turbulent" when there is only one molecule in flight, in a vacuum. I believe that the idea here is that although the molecule can only pass through one of the slits in the grating, it behaves as if it passed through all of the slits simultaneously and interfered with itself on the way through, thereby affecting the probability of where it strikes the detector.

IANA physicist, tho.

Re:Holy Hell that's large (1)

bunratty (545641) | about 2 years ago | (#39495743)

Imagine, we previously thought this only happened with quantum particles

As opposed to what exactly?

Re:Holy Hell that's large (1)

b4dc0d3r (1268512) | about 2 years ago | (#39496213)

As opposed to anything larger than a photon, at first. The famous "dual slit" experiment. Then electrons, in the understanding of photovoltaic effect. Protons and Neutrons are quite a bit larger, and atoms larger yet. Then molecules of the same atom (buckyballs). Now we have a particle, with combinations of different atoms.

For most people who know anything about this duality, they learned about the dual-slit experiment, so your most common answer is likely to be "photon", the "quantum of light" and therefore a "quantum particle".

Richard Feynman (4, Interesting)

little1973 (467075) | about 2 years ago | (#39493797)

I do not believe in particle-wave duality. I believe in Feynman's path integral formulation.

http://en.wikipedia.org/wiki/Path_integral_formulation [wikipedia.org]

Read QED if you want to know more of this.
http://en.wikipedia.org/wiki/QED:_The_Strange_Theory_of_Light_and_Matter [wikipedia.org]

Using path integral a particle does not need to interference itself in order to produce the interference pattern.

Re:Richard Feynman (1)

Anonymous Coward | about 2 years ago | (#39494037)

I do not believe in particle-wave duality. I believe in Feynman's path integral formulation.

http://en.wikipedia.org/wiki/Path_integral_formulation [wikipedia.org]

I'd have more confidence in your opinion if you said something like "I find Feynman's path integral formulation more convincing". I guess it's just a matter of word choice but "I believe in" doesn't really sound like someone who's making a rigorous analysis of the evidence.

Re:Richard Feynman (1)

Eponymous Hero (2090636) | about 2 years ago | (#39499209)

except that science is just as much a religion as catholicism. any "truth" you think you observe is negated by the bias of your observation. what it all comes down to is what story sounds good to you.

Re:Richard Feynman (0)

Anonymous Coward | about 2 years ago | (#39501851)

Do you really believe this?! The only "faith" we need to hold in the scientific method is a few simple axioms such as the "law" of noncontradiction or the simple idea that things actually exist in some sense at all, even if only in our minds. You are so exponentially, fractally wrong there is not enough space in the universe to hold all the bits representing the number which quantifies how wrong you are.

And before you ask, yes, I have done years and years and years of religion studies, Bible and apologetics research, and so forth. I am not "just another deluded materialist." Your religion is wrong on its own merits, not some obscure philosophical basis.

Re:Richard Feynman (5, Interesting)

FrangoAssado (561740) | about 2 years ago | (#39494215)

It's great to study, understand and use Feynman's path integral, especially since it leads to new insights about the nature of Quantum Mechanics (plus, seeing the familiar face of the principle of least action in the quantum world is just awesome). But it seems counter-productive to limit yourself to it. For example, some problems that are relatively simple to solve using the "usual" methods (i.e., thinking about waves and using the Schrodinger equation) can become intractable math nightmares with Feynman's path integral. I'm sure there are problems for which the reverse is true, too.

Most people who work with QM seem to take a very pragmatic approach when dealing with problems outside the foundations of QM: use whatever works for you for the problem at hand. Peter Shor (the guy who invented the quantum algorithm to factor numbers in polynomial time) once wrote:

Interpretations of quantum mechanics, unlike Gods, are not jealous, and thus it is safe to believe in more than one at the same time. So if the many-worlds interpretation makes it easier to think about the research you’re doing in April, and the Copenhagen interpretation makes it easier to think about the research you’re doing in June, the Copenhagen interpretation is not going to smite you for praying to the many-worlds interpretation.

(Source [scottaaronson.com])

And I agree that people should read QED: it's very easy to read, and it's great.

Re:Richard Feynman (2)

NicknameAvailable (2581237) | about 2 years ago | (#39494641)

So if the many-worlds interpretation makes it easier to think about the research you’re doing in April, and the Copenhagen interpretation makes it easier to think about the research you’re doing in June, the Copenhagen interpretation is not going to smite you for praying to the many-worlds interpretation.

Well of course not, the many-worlds interpretation will smite you for praying to the copenhagen interpretation - April --> June. I can't stand people that play on semantics to make an argument.

Re:Richard Feynman (1)

gfreeman (456642) | about 2 years ago | (#39495035)

I can't stand people that play on semantics to make an argument.

You cannot participate in a discussion (argument) unless all parties agree on the meaning of both premises (whether either premise is right or wrong is immaterial).

Semantics: The branch of linguistics and logic concerned with meaning.

Therefore if you do not apply semantics to your argument, you have lost before you open your mouth.

Re:Richard Feynman (1)

b4dc0d3r (1268512) | about 2 years ago | (#39496335)

It was a terrible analogy to begin with, not an argument. And you are correct that he argued one side but forgot the other.

It was more of an excuse to take a a jab at multitheism, if not deism completely, and I'm sure there are better ways to explain it without inserting personal bias.

The premise probably included the assumption that since people have believed both ways, neither one could be called the correct way. This is the scientific method, if contradictory results are observed no conclusion can be made and neither is correct. Therefore in his mind, no smiting would happen at all.

Once you understand the semantics involved, instead of picking one superficial blemish, it is much easier to discuss these things. Context is the key to understanding.

Re:Richard Feynman (1)

CSMoran (1577071) | about 2 years ago | (#39499105)

This is the scientific method, if contradictory results are observed no conclusion can be made and neither is correct.

Why exactly can't one of them be correct?

Re:Richard Feynman (1)

Anonymous Coward | about 2 years ago | (#39494883)

For example, some problems that are relatively simple to solve using the "usual" methods (i.e., thinking about waves and using the Schrodinger equation) can become intractable math nightmares with Feynman's path integral. I'm sure there are problems for which the reverse is true, too.

Which is why we have this Schrödinger-Feynman duality to explain the whole.. ;)

Re:Richard Feynman (0)

Anonymous Coward | about 2 years ago | (#39496657)

I think the issue is with the word "believe."

Re:Richard Feynman (5, Informative)

DMiax (915735) | about 2 years ago | (#39494323)

There is no particle-wave duality. Every particle is only a wave and sometimes, if you look from very far (or at high temperatures) it seems to behave as a point-like object.

In any case it is not like path integrals are alternative to the normal schroedinger wavefunction formulation. See the work of Dyson for that, or simply the Feynman-Kac formula. At the fundamental level path-integrals ar just combinations of double-slits experiments in a very abstract space (Trotter's formula).

And yes, in the path integral a particle interferes with itself. You'll notice that you have to take into account and sum paths going through different slits.

I do work in the path integral formulation because I think it is more elegant, but it is not an alternative to the "traditional" wavefunction approach (hey, path integral is not exactly new anymore). It is the same as choosing cartesian or spherical coordinates.

The tagline is: path integrals do not describe different physics.

Re:Richard Feynman (3, Informative)

blutfink (793915) | about 2 years ago | (#39494757)

I do not believe in particle-wave duality. I believe in Feynman's path integral formulation.

This is not related in the way you might think it is. The former is a philosophical problem in the interpretation of quantum mechanics, the latter is one of several ways of resolving this problem in practice.

Re:Richard Feynman (2)

blueg3 (192743) | about 2 years ago | (#39496355)

Particle-wave duality is not philosophical. What it means and whether an object "really" is both a particle and a wave might be philosophical questions, but that's not what's meant in physics when one refers to "particle-wave duality". It's the observable (and, indeed, observed) fact that objects exhibit a set of properties that are both classically wave-like and classically particle-like.

In modern quantum mechanics you don't even really talk about particle-wave duality much. It's simpler to approach it from the perspective that all objects are described by their wavefunction and that observation causes a collapse of the wavefunction with respect to the observed variable.

Re:Richard Feynman (1)

elsurexiste (1758620) | about 2 years ago | (#39496573)

IMHO, I find DeBroglie-Bohm theory much more convincing, even palatable, as it doesn't deal with wavefunction collapse and other "Copenhagian" quirks.

Re:Richard Feynman (1)

blutfink (793915) | about 2 years ago | (#39497563)

We're not that far apart. I meant it in the sense that it is an empirical phenomenon that poses a problem in the interpretation of QM. The concept is philosophical in the sense that it is rather used by philosophers or teachers and not so much by practicing physicists.

Re:Richard Feynman (0)

Anonymous Coward | about 2 years ago | (#39496975)

The correct answer is: Both.

Re:Richard Feynman (0)

Anonymous Coward | about 2 years ago | (#39498973)

Actually the particle does interfere with itself in Feynman's path integral. Thats what the sum over histories is doing, if you recall the prescription is Sum over histories of exp(iS), thus you asign a phase (an angle) to every path and sum over all posible paths. Angles can cancel each other out producing interference.

Re:Richard Feynman (1)

bcrowell (177657) | about 2 years ago | (#39500767)

I do not believe in particle-wave duality. I believe in Feynman's path integral formulation.

This is total nonsense. You might as well say that you don't believe in addition, you believe in electronic calculators instead. A calculator is one method for adding numbers. The Feynman path integral formulation is one method for doing calculations in quantum mechanics, which has wave-particle duality.

Future scaling (1)

Ironix (165274) | about 2 years ago | (#39493879)

At this rate it won't be long before they're able to do the same with live cats.

Maybe.

Re:Future scaling (0)

Anonymous Coward | about 2 years ago | (#39493917)

You mean this, in real life?

http://www.youtube.com/watch?v=QH2-TGUlwu4

Re:Future scaling (1)

Rogerborg (306625) | about 2 years ago | (#39493973)

Are you thinking what I'm thinking? Narrow slits, an industrial press...

Re:Future scaling (1)

Neil Boekend (1854906) | about 2 years ago | (#39494127)

IANAAP, but I once heard everything has a base frequency (not mechanical, but something else, based on the mass of the object). With the speed of the cat this results in a wavelength. I'd guess the maximum slit size is connected to the resulting wavelength (a to wide a slit would not give an interference pattern). The question is: how fast do we need to launch the cat (using a catapult of course) to get the wavelength long enough to make the maximum slit wider than the cat?

Re:Future scaling (1)

BasilBrush (643681) | about 2 years ago | (#39496989)

If you butter both sides of the cat, you can probably get them to go through narrower slits. Hope that helps.

Re:Future scaling (1)

flappinbooger (574405) | about 2 years ago | (#39494885)

Are you thinking what I'm thinking? Narrow slits, an industrial press...

so if the splatter pattern has "waves" it will indicate correlation with the WPD of matter?

Re:Future scaling (0)

Anonymous Coward | about 2 years ago | (#39495531)

...a high-energy cat accelerator...

Re:Future scaling (1)

turbidostato (878842) | about 2 years ago | (#39497793)

"At this rate it won't be long before they're able to do the same with live cats"

Impossible. For that to happen they should first settle on the cat being in fact alive!

Half photons (0)

Anonymous Coward | about 2 years ago | (#39494305)

You can have half a photon, or half of anything.

Realize the photon is only a discrete packet because the only way we can detect it is by watching the promotion and demotion of electrons through full levels, and thus we can't image half a photon. Examine the physics that requires discrete packets and you'll realize it's circular reasoning.

So they can pat themselves on the back that they can see this with fluorescence microscopy and never ask what limit there is in the flourescence microscope that would give rise to observing a wave-particle duality if the particles in question WERE GROUPS OF VERY MUCH SMALLER THINGS THAN WE CAN EVER OBSERVE.

Re:Half photons (3, Informative)

ThePeices (635180) | about 2 years ago | (#39494365)

Dude, you cannot have half a photon. Its at least one or none.

You can have a photon with half the energy of another photon, but you cannot have half a photon.

Ill try another tact....If you had a hole, and filled in half of it, you would be left with a hole. There is no such thing as half a hole, but there is such thing as a hole half the size of another hole.

Not the best analogy, but it all boils down to one simple fact. A quantum of light ( a photon ) is the smallest unit of light.

Re:Half photons (1)

Anonymous Coward | about 2 years ago | (#39496439)

But a photon is not a wave. In fact, there is nothing waving. It is the electromagnetic field that changes state. So it should be possible to represent a photons electromagnetic state change through space as a series of dominos falling, one after the other, carrying energy as it goes. In that case, it's actually a quarter wave, where the velocity is determined by how close the dominoes are to each other. This "domino spacing" changes depending on the density of "vacum space" which is clearly dependent on mass, which causes gravity. The more dense "space" is, the slower the dominos fall. This fixes the relationship between Einstein's gravity and quantum mechanics.

Yes you can (0)

Anonymous Coward | about 2 years ago | (#39497717)

And the reason you think you can't is because you can only see a whole photon, by virtue of promoting an electron.

And the sooner you realize it, the more duh this stuff is.

Re:Yes you can (1)

shutdown -p now (807394) | about 2 years ago | (#39501933)

If there's no way you or anyone else can detect a "half photon" - i.e. if it doesn't have any observable effect on the universe whatsoever - then it only exists in a sense that the Invisible Pink Unicorn exists.

Re:Half photons (0)

Anonymous Coward | about 2 years ago | (#39498909)

You can split a photon in half in the sense it has half the probability of going one way or the other. But this is not the same as saying a photon is a particle made of two discrete hemiphotons. First off, you can construct a set up with three or more slits instead of two, or you can have a setup that splits the photon into a 40-60 portion, or any other fraction or combination. Second, there are detection methods for photons that do not require raising electrons by discrete steps, e.g. Compton scattering. Third, this applies to particles other than photons, which have additional varieties of detection.

Most importantly, there is the other half of the classic double-slit experiment: after you have "split" the photon, if you interfere or catch the photon at one slit, nothing comes out the other. If there were two hemiphotons going through separate slits, then what happens to one shouldn't affect the other. And if you were to argue that our whole photon detection methods have only a 50% chance of seeing a hemiphoton so as to appear a whole photon only came through half the time, this still wouldn't work. If you had a detector behind each of two slits, you would have a 25 percent chance of both detecting hemiphotons at the same time in such a case. But this doesn't happen, with two detectors behind the slits, you only ever detect a photon behind one slit at a time, never a coincidence.

Just in: Prisoner escapes from jail cell (1)

flyingfsck (986395) | about 2 years ago | (#39494313)

Breaking news: By exploiting wave and particle duality, the mad scientist Doctor Who, escaped from his jail cell...

Re:Just in: Prisoner escapes from jail cell (1)

Qango (1181513) | about 2 years ago | (#39494369)

Damn! Now we're going to see this in an episode!

Re:Just in: Prisoner escapes from jail cell (0)

Anonymous Coward | about 2 years ago | (#39498843)

One should certainly hope so...

Macroscopic wave–particle duality (4, Informative)

advid.net (595837) | about 2 years ago | (#39494359)

Wave-particle duality has yet been observed with much bigger objects, on different physical basis but with astonishingly equivalent behaviour.

A 'walking' drop on a liquid surface behave like a particle with wave properties: diffraction, interference patterns, vibration quantization.

First, in a vibrating container they put a liquid like silicon oil, vibrations are just bellow the Faraday instability threshold. Then a drop of the same liquid is dropped on the surface, but it does not coalesce, it bounces. And further bounces make a static wave pattern on the liquid surface just bellow the drop and its immediate neighborhood. As the spike grows, instability increases and the drop slides down the spike, and start moving horizontally.

Then they have a combo object drop+wave pattern moving at 1/10th the speed of wave in this liquid, straight. They call it a walker.

What is really amazing is that the wave pattern below the drop has some kind of memory: it has accumulated energy from several drop bounces. It can also make the drop see "forward", as the small wave pattern bounces back from nearby obstacles. So the drop is "aware" of its environment and "recall" the path it has followed.

Diffraction is observed and explained by the multiple reflexions the wave makes when the drop passes through a small hole, randomizing the wave pattern and the angle of the path afterward. Interference patterns observed are explained a la de Broglie: as the drop passes through one of the two holes, its associated wave passes through both, carrying forward the message of the second hole to the drop and changing the statistical repartition of the drop's path direction. One more stunning result: they are circling the drop by moving the container (Coriolis), then the associated wave adopts a discrete series of pattern, depending on the speed and radius. Very much like the energy quantization of electrons.

English (and French) abstract [archives-ouvertes.fr]
A short article (French but it has photos and formulas) [sfpnet.fr]
Full thesis (French,10Mb)" [archives-ouvertes.fr]

Re:Macroscopic wave–particle duality (4, Interesting)

chichilalescu (1647065) | about 2 years ago | (#39494951)

umm... the research you're talking about, while interesting, is not an example of quantum phenomena.
the message of the article discussed here is "matter behaves in the weird quantum way even when you're talking about molecules". i.e. "we made an experiment with real molecules, and they act as predicted by quantum mechanics". it is a verification of theoretical predictions, with the purpose of strengthening our belief that quantum physics is "true". it is conceivable, while unlikely, that they would have obtained different results, thus implying that the passage from the quantum world to the macroscopic world is much more complicated then we currently believe.
the message of the thesis you link to is "with a properly set up classical experiment, we can reproduce quantum physics behavior". even if the molecules of liquid are described by classical physics, once you put a drop on a surface that vibrates very rapidly, you will observe that the drop bounces, and it is being carried by a wave on the surface of the liquid. by design the particle is carried by a wave, but only classical physics is relevant. they do talk about quantum physics because (in a somewhat funny situation) the simplification of the classical physics leads to equations that resemble those in quantum physics. it's just like you can write the same equations to describe sound and radio waves, even though the reasons sound waves exist are completely different from the reasons radio waves exist.

What is a quantum particle wave composed of? (3, Interesting)

master_p (608214) | about 2 years ago | (#39494451)

We know that water waves are composed of watr molecules, heat waves are composed of air moledcules and electromagnetic waves are composed of electrons or photons.

What is a quantum particle wave composed of?

Re:What is a quantum particle wave composed of? (1)

advid.net (595837) | about 2 years ago | (#39494603)

What is a quantum particle wave composed of?

I think we'll find out what the matter wave is made of, after we started looking in that direction.

Quantum physics is correct in the equations to account for the observations, but deceptive in that it leads us to conclude of reality.

I hope that the experiment of macroscopic wave-particle duality will redirect research towards the hypothesis of matter waves rather than quantum particles.

Re:What is a quantum particle wave composed of? (1)

Anonymous Coward | about 2 years ago | (#39494931)

We know that water waves are composed of watr molecules, and electromagnetic waves are composed of electrons or photons.

What is a quantum particle wave composed of?

The waves in the ocean have very little to do with the water. The waves are as a result of the forces acting on the water (wind, tides, probably air/water surface friction, etc).

heat waves are composed of air moledcules

The heat has nothing to do with the air. What you experience as heat is the release of energy as photons from the moving air molecules. The air is moving, but it is the release of the photons is the cause of the heat.

Your car gets hot in the sun because the car absorbs many photons of energy. You get burned when you touch your hot car as the photons are then transferred to you. Yes, the photons do demonstrate wave-like properties but what we are calling a wave here has nothing to do with ocean waves or the wind. (Also, the large scale movements of the wind don't necessary produce any wavelike motions. It can but normally you'll get a blast of air in more or less a straight direction.)

What is a quantum particle wave composed of?

There is no such thing as a quantum particle wave. The answer you're probably looking for is the part you said about electromagnetic waves being made up of photons, which is more or less accurate but does not give the whole picture. In a general sense you could call a bunch of photons a quantum wave, but that would be kinda misleading.

Re:What is a quantum particle wave composed of? (0)

Anonymous Coward | about 2 years ago | (#39495407)

I should probably clarify the main point I was getting at in the first two parts: ocean waves and air currents do at a low level rely on quantum mechanical effects, BUT these effects apply everywhere. A solid chunk of metal or a living creature are just as "wavey" as the ocean and air.

Re:What is a quantum particle wave composed of? (0)

Anonymous Coward | about 2 years ago | (#39494993)

It's roughly composed of square roots of probabilities. More precisely, it's composed of complex numbers whose norm squared gives the probability of the particle being there.

Re:What is a quantum particle wave composed of? (1)

Anonymous Coward | about 2 years ago | (#39495557)

What is a quantum particle wave composed of?

The probability amplitudes of a quantum particle.

Re:What is a quantum particle wave composed of? (2)

blueg3 (192743) | about 2 years ago | (#39496403)

Electromagnetic waves aren't composed of electrons at all. Electromagnetic waves are composed of photons in the sense that the photon is, by definition, the particle representation of an electromagnetic wave or, equally, the force-carrier for the electromagnetic force.

In the same sense, what "composes" the quantum wavefunction of an electron is an electron. What composes the quantum wavefunction of an up quark is an up quark.

Re:What is a quantum particle wave composed of? (0)

Anonymous Coward | about 2 years ago | (#39496811)

I'd say it's a propogation effect on quantam particles. Mind you, one or some quantam particles rather than all, since all would then constitute one of the former waves mentioned.

Could it be argued that the former three waves you mentioned are just quantam waves of varying degrees of intesity, and range of effect (scale if you will)?

Re:What is a quantum particle wave composed of? (0)

Anonymous Coward | about 2 years ago | (#39497055)

Cats, clearly.
Engaging all sorts of furniture-harming activities while you're not watching; then, as soon as you observe them, they collapse into a purring state, bribing you for food and pettins.

Ard, Anonymous Cow.

Re:What is a quantum particle wave composed of? (0)

Anonymous Coward | about 2 years ago | (#39498205)

Cats. What is ya, ignorant?

Frost poem (1)

Jeff1946 (944062) | about 2 years ago | (#39496697)

The dual slit experiment reminds me of Frost's poem, "The Road not Taken." Even though you take a fork in the road you will know you could have taken the other road and wonder what would have happened if I took the other road. If the path was blocked then you wouldn't wonder about it.

The duality (0)

Anonymous Coward | about 2 years ago | (#39498263)

The entire wave/particle "duality" proves that we don't actually have a fundamental understanding of how the universe works. We have some models that work for what we do, but no way to discover or utilize fundamental properties of the universe.

This is why you will never have what you nerds want so badly (gravity and inertia modification, FTL transport or teleportation, matter replication, etc.).

The entire scientific establishment needs gutted and it needs to return to its roots. People need to be encouraged to think of wild ideas and test them. If you do that now, you'll end your career as a scientist. See Dr. Myron Evans.

And stop making light of Schrodinger's thought experiment. It was meant at the time to demonstrate how absurd quantum theory is. Now it is taught as fact and people go on about how "far out" physics is and that they will never understand it. Please... Something as idiotic as the cat being both dead and alive until observed should tell you that maybe you've got a problem with your theory. Quantum mechanics is a statistical model that fits the universe. It's not a useful theory of the universe.

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