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Collapse of Quantum Wavefunction Captured In Slow Motion

samzenpus posted about 10 months ago | from the look-at-this dept.

Science 242

ananyo writes "It is the most fundamental, and yet also the strangest postulate of the theory of quantum mechanics: the idea that a quantum system will catastrophically collapse from a blend of several possible quantum states to just one the moment it is measured by an experimentalist. Researchers have now been able to capture that collapse through the use of weak measurements — indirect probes of quantum systems that tweak a wavefunction slightly while providing partial information about its state, avoiding a sudden collapse. Atomic and solid-state physicist Kater Murch of the University of California, Berkeley, and his colleagues performed a series of weak measurements on a superconducting circuit that was in a superposition — a combination of two quantum states. They did this by monitoring microwaves that had passed through a box containing the circuit, based on the fact that the circuit's electrical oscillations alter the state of the microwaves as they pass through the box. Over a couple of microseconds, those weak measurements captured snapshots of the state of the circuit as it gradually changed from a superposition to just one of the states within that superposition — as if charting the collapse of a quantum wavefunction in slow motion."

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No video in the link (4, Informative)

Pikoro (844299) | about 10 months ago | (#45089521)

So don't bother unless you want to read a dry paper.

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45089565)

What did you expect a video of, exactly?

Re:No video in the link (5, Funny)

camperdave (969942) | about 10 months ago | (#45089973)

What did you expect a video of, exactly?

Well, I was expecting a slow motion video of the collapse of a quantum wavefunction, myself.

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45089581)

So don't bother unless you want to read a dry paper.

Damn the lazy scientists, couldn't even be bothered to film an experiment with subatomic particles, come on, what is this, 1980? Everybody's got an iPhone these days!

Re:No video in the link (1)

Anonymous Coward | about 10 months ago | (#45089635)

The problem is that they act like their are pictures or something to see..
To quote TFA:

Slow-motion movie

Then no video...

Re:No video in the link (4, Funny)

Cryacin (657549) | about 10 months ago | (#45089751)

Everybody's got an iPhone these days!

Great. Filmed in portrait.

Re:No video in the link (0)

Lumpy (12016) | about 10 months ago | (#45089797)

http://www.youtube.com/watch?v=-fSqFWcb4rE [youtube.com]

They have a video camera that takes frames faster than light can travel, so they have the technology. Problem is it requires the subject to be ungodly bright.

So unless the collapse is holy shit bright, it cant be imaged.

But they could do an animation that explains it to us muggles that dont want to read through a paper written by people that are intentionally writing for getting tenure or funding.

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45089901)

It is probably also important that the measurements were of microwaves... from a single point, so there is no direct 2D measurements involved that would make a camera or any vague sense of a camera relevant. The actual article [nature.com] has the figures available for free, even if the article itself is pay-walled. Of note, it is in the letters section of Nature, meaning they were trying to get the results out quickly and tersely, so it wouldn't be surprising they don't have any general public oriented animation, even if someone is planning to do such PR work down the line.

Re:No video in the link (5, Informative)

frinsore (153020) | about 10 months ago | (#45090019)

http://www.youtube.com/watch?v=-fSqFWcb4rE [youtube.com]

They have a video camera that takes frames faster than light can travel, so they have the technology. Problem is it requires the subject to be ungodly bright.

No. No they don't. They have a "camera" with a very fast shutter speed. Then they take millions of pictures of different laser pulses and stitch them together to create an animation that mimics a single laser pulse.

I know that the comments on youtube are pretty poor and that most people rarely read articles but this is a really cool video and if you can't be bothered to understand what you're looking at then I feel sorry for you.

Re:No video in the link (2, Funny)

Anonymous Coward | about 10 months ago | (#45089589)

Everyone knows that when you try to capture a quantum state on video, all you end up with is cats. How else do you explain all the cat videos on Youtube?

Re:No video in the link (4, Funny)

NoNonAlphaCharsHere (2201864) | about 10 months ago | (#45089813)

That can't be true; if it were, more of them would be dead.

Re:No video in the link (2)

PolygamousRanchKid (1290638) | about 10 months ago | (#45089647)

Video? When I read "captured" I thought they meant "in captivity", like they had the Quantum Critter in a box with the cat or a microscopic cage or something like that.

Re:No video in the link (5, Insightful)

r1348 (2567295) | about 10 months ago | (#45089671)

Did you really expect to see a video of a quantum wavefunction?

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45089711)

I did.

http://io9.com/the-first-image-ever-of-a-hydrogen-atoms-orbital-struc-509684901

Re:No video in the link (5, Funny)

Anonymous Coward | about 10 months ago | (#45089725)

I did and I didn't.

Re:No video in the link (5, Funny)

Anonymous Coward | about 10 months ago | (#45089741)

±5 Funny

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45089771)

LOL (probably)

Re:No video in the link (1)

Lumpy (12016) | about 10 months ago | (#45089805)

You win TWO internets!

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45089997)

But as soon as I try to use one, the other one disappears?

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45090001)

video - or it didn't happen!

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45090065)

No, but "capture in slow motion" as stated in the summary title normally means in video. So they shouldn't have said that because that isn't what they did. What they did is measured a progression of quantum superposition states.

Re:No video in the link (1)

Dunbal (464142) | about 10 months ago | (#45089707)

Sure there was video in the link! Oh, wait... you must have gotten the "other" version. Well, quantum stuff can suck sometimes but hey, at least you're not a cat!

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45090509)

"....at least you're not a cat!"

Well, I'm uncertain about that. I could be a fuzzy pink elephant at any given point in time, but given how unlikely that is, it will be for a nearly infinitely small period of time.

Or something like that. Quantum hurts my brain.

Re:No video in the link (1)

Dunbal (464142) | about 10 months ago | (#45090773)

Quantum hurts my brain.

Only because you haven't taken the appropriate precautions. Surgeons wear gloves. Soldiers wear body armor. And quantum scientists... well here... puff puff pass, then your brain won't hurt so much with quantum...dude

Re:No video in the link (1)

PopeRatzo (965947) | about 10 months ago | (#45090059)

So what you're saying is, "pictures or GTFO"?
'
I'm with that.

Re:No video in the link (1)

fatphil (181876) | about 10 months ago | (#45090655)

GTFO?

Grand Theory Fields
            ^--------  Of

Re:No video in the link (1)

marcello_dl (667940) | about 10 months ago | (#45090461)

Uh.. this is slashdot, you DO NOT observe the article anyway, or strange things may occur.

Speaking of strange, why do we keep calling stuff like this "strange"? at a microscopic level matter behave differently, ok. Had we mostly experience of quantum states, we would classify classical mechanic strange.
It is what it is. Model it with known concepts if you can, but don't try to fit everything in existing categories.

Re:No video in the link (1)

ShanghaiBill (739463) | about 10 months ago | (#45090651)

Speaking of strange, why do we keep calling stuff like this "strange"?

Because it is strange. I am an engineer, not a physicist, but I took plenty of physics courses in college, and have kept up on progress in QM. This experiment is not the result that I would have expected. I had always understood that it is either one state or the other, all or none, and the collapse was instantaneous with any measurement. To now learn that none of that is true, that the collapse can be "partial", and that intermediate measurements can be made, is very strange indeed. Fascinating stuff.

As both computation and memory technology move into the quantum domain, this is likely to have real, practical implications. For instance, if quantum states take time to collapse, that may put limits on the speed of quantum hardware.

Re:No video in the link (1)

fatphil (181876) | about 10 months ago | (#45090721)

If you observe the paper, you change it?

And thus wikipedia and blogs were invented.

Re:No video in the link (1)

fatphil (181876) | about 10 months ago | (#45090683)

So is the paper like a flip book?

Re:No video in the link (0)

Anonymous Coward | about 10 months ago | (#45090815)

Dry???

Turn in your nerd card. TL;DR==aliterate (not to be confused with illiterate)

BUT WHAT OF CTE ?? (-1)

Anonymous Coward | about 10 months ago | (#45089523)

Should American football be banned ?? Think of the children !!

Re:BUT WHAT OF CTE ?? (-1)

Anonymous Coward | about 10 months ago | (#45089555)

Americans should be banned. From the world.

Re:BUT WHAT OF CTE ?? (1)

hawkinspeter (831501) | about 10 months ago | (#45089679)

That seems a little harsh on everyone from Canada, Mexico, Brazil etc.

Re:BUT WHAT OF CTE ?? (1)

pahles (701275) | about 10 months ago | (#45090069)

Then call it US Football!

Re:BUT WHAT OF CTE ?? (3, Funny)

hawkinspeter (831501) | about 10 months ago | (#45090185)

As I'm in the UK, I'd prefer to call it American-style HandEgg. Football is a game played using a (round) ball and predominately using your feet.

Re:BUT WHAT OF CTE ?? (0)

Anonymous Coward | about 10 months ago | (#45090441)

Wow! A brit with some wit. You sir, are a credit to your island race. Say hi to the queen for me.

P.S. Ties in the unAmerican football are poorly solved. Take notice that in American football it is called SUDDEN DEATH! while in unAmerican football it is called kickball, and without surprise, the only time unAmerican football is more exciting than, say, American baseball, though only or a triffle few seconds. But it may be the only score in an otherwise very long sit, so something to go to the pub and fight about later. Fights by the fans against the other fans? No wonder there were two world wars started over there.

Cricket. Now there is a sport no one anywhere understands. Maybe the cast of Monty Python (excluding that Americam).

That's no Quantum Wavefunction... (0)

Anonymous Coward | about 10 months ago | (#45089535)

IT'S A SPACESHIP!

Re: That's no Quantum Wavefunction... (0)

Anonymous Coward | about 10 months ago | (#45089543)

Hiding behind a comet.

catastrophically collapse (1)

Anonymous Coward | about 10 months ago | (#45089573)

"Catastrophically collapse", really? What's catastrophic about it?

Re:catastrophically collapse (2)

DeathToBill (601486) | about 10 months ago | (#45089623)

My thought exactly. Someone saw the word 'collapse' and thought, "Not dramatic enough."

OH MY GOD THAT WAVE FUNCTION COLLAPSED! THERE GOES ANOTHER ONE!

Re:catastrophically collapse (1)

Joce640k (829181) | about 10 months ago | (#45089765)

Every time you wave your arm in the air you destroy an infinite number of universes.

In a lot of them you're currently having sex with Miley Cyrus.

(Whether or not that's "catastrophic" is up to you...)

Re:catastrophically collapse (1)

pahles (701275) | about 10 months ago | (#45090081)

It could wreck you...

Re:catastrophically collapse (5, Insightful)

tgd (2822) | about 10 months ago | (#45089631)

"Catastrophically collapse", really? What's catastrophic about it?

Generally speaking, when it collapses, it involves destroying a nearly infinite number of possibilities in an absolutely irreversible way. The collapse is complete.

Its pretty much the definition of catastrophic.

That said, its a bit of hyperbole that probably wasn't needed. But its not inaccurate.

Re:catastrophically collapse (1)

Anonymous Coward | about 10 months ago | (#45089655)

How can anything be "nearly infinite"?

Re:catastrophically collapse (2)

chill (34294) | about 10 months ago | (#45089737)

Not familiar with the mathematical concept of "infinity minus 1" are you?

Re:catastrophically collapse (0)

Anonymous Coward | about 10 months ago | (#45090029)

Not familiar with the mathematical concept of "infinity minus 1" are you?

Not answering the question, are you?

Re:catastrophically collapse (0)

Anonymous Coward | about 10 months ago | (#45090127)

How can anything be "nearly infinite"?

It can be bijectively mapped to a proper subset of itself, except for one element ;)

Oblig /. comment (0)

Alomex (148003) | about 10 months ago | (#45089575)

Correlation does not imply causation

Re:Oblig /. comment (1, Funny)

tgd (2822) | about 10 months ago | (#45089639)

Correlation does not imply causation

Well, if we're going to toss out /. comments that are unrelated to the article ... hmmm....

"Imagine a Beowulf cluster of these superconductors!"

"It only collapsed because of anticompetitive market practices through a series of shell companies that Microsoft controls."

or

"I'm not sure what to think of this until PJ tells me what to think. I'm so PISSED at the NSA for taking her from me!"

Re:Oblig /. comment (1)

Anonymous Coward | about 10 months ago | (#45089685)

The point is that people pull out the "correlation does not imply causation" meme whenever a study is quoted, whether warranted or not in contrast to all other comments you list.

Re:Oblig /. comment (1)

JustOK (667959) | about 10 months ago | (#45089775)

There must be some correlation that causes it.

Re:Oblig /. comment (1)

Canazza (1428553) | about 10 months ago | (#45089727)

I'm not convinced it colapsed until Netcraft confirms it?

Re:Oblig /. comment (1)

foniksonik (573572) | about 10 months ago | (#45089831)

In Soviet Russia it collapses you!

Re:Oblig /. comment (1)

Zaatxe (939368) | about 10 months ago | (#45089857)

Re:Oblig /. comment (1)

Anonymous Coward | about 10 months ago | (#45089889)

That is funny, and indeed there are (many) cases where the meme is warranted.

There are equally many when the study is of the form "finger pulls trigger, bullet leaves rifle, deer falls dead" concluding "firing bullets kill deer" only to have some noob smugly trod out the "correlation does not imply causation" meme.

Illusion? (1)

K. S. Kyosuke (729550) | about 10 months ago | (#45089579)

I thought that this "waveform collapse" stuff was an illusion on our part, signifying a certain lack of understanding.

Re:Illusion? (0)

DeathToBill (601486) | about 10 months ago | (#45089621)

Wrong.

Re:Illusion? (2)

Pino Grigio (2232472) | about 10 months ago | (#45089673)

He's not wrong really. It's a question of interpretation. What the OP's are measuring is de-coherence, not "collapse". I mean every time you take a measurement you're measuring "collapse" from a set of probabilities to an actual state, so that's not a particularly interesting thing to do in this context.

Re:Illusion? (4, Informative)

amaurea (2900163) | about 10 months ago | (#45089703)

Not necessarily. Wavefunction collapse is a part of some interpretations of quantum mechanics, such as the venerable Copenhagen interpretation [wikipedia.org] , but many other popular interpretations do not include it. A prominent example of the latter is the many worlds [wikipedia.org] universal wavefunction [wikipedia.org] interpretation.

Interpretations of quantum mechanics are usually mathematically equivalent, which means that they make exactly the same physical predictions. So an experiment that would be a measurement of wavefunction collapse according to the Copenhagen interpretation would be a measurement of observer entanglement or similar in the many worlds interpretation, and something else in other interpretations. It's a bit like one theory saying that A=4/2 and another saying A=1*2. They agree on every prediction (A=2), and only differ in how they are formulated, and the intuition they give people.

Popular science reporting is usually very Copenhagen-heavy, but physicists are more mixed [wikipedia.org] , and a large fraction of them would disagree that this experiment has measured wavefunction collapse (i.e. they will think it measured something else interesting).

Oops, wrong link (3)

amaurea (2900163) | about 10 months ago | (#45089717)

That was supposed to be "... but physicists are more mixed [preposterousuniverse.com] ."

Re:Illusion? (1)

aaaaaaargh! (1150173) | about 10 months ago | (#45089801)

Interpretations of quantum mechanics are usually mathematically equivalent

Now I'm not a physicist but I'm doubtful about that one, for I've heard that the many worlds interpretation is in principle testable against the Copenhagen interpretation.

Could some physicist explain this little popular science riddle? Preferably with a car analogy.

Re:Illusion? (1)

Anonymous Coward | about 10 months ago | (#45089941)

in this context, it is kind of the definition of "interpretation." They are called interpretations, because the basic math of quantum mechanics is set regardless of what interpretation you want to use or not use, and the interpretation only comes in when you want to have a more intuitive sense of what the math actually means. Since you are just reinterpreting what the math means, you won't be changing the actual predictions. The only way a difference would come up is if you find a situation where the math makes no sense to one interpretation, although more likely, you just have situations where one interpretation makes it easier to come up with ideas of how to solve the math, even though the other ones still work out in the end.

Re:Illusion? (1)

hawkinspeter (831501) | about 10 months ago | (#45089743)

There's a certain amount of presumption with the whole superposition of states and then finding only one state upon measurement. However, it's not exactly easy to measure the superposition of states when any such measurement causes it to "collapse" into one particular state.

Some people prefer the many-worlds explanation where we "select" a reality by performing the measurement. That would imply that the waveform doesn't collapse as such, but the difference is only in interpretation and is not measurable.

We know "what" happens very precisely, but the "why" part is open to interpretation and there is not really a consensus on that.

OT: Question about waveforms (2)

Stolzy (2656399) | about 10 months ago | (#45089591)

I know that this question is off topic, but I also know there will be many readers of this story who may be able to answer my question. It's something I'd desperately like an answer to, having posted it around to a few folks with no response. . .My understanding of electromagnetics is that there is a waveform. I'd like to know if it is possible for a directly inverse waveform could coincide with, say, a photon of red or blue light, in such a way that it cancels the waveform out, the same way that an inverse waveform in audio engineering will cancel out any sound when played in conjunction with it's natural state.

Is it possible that two directly inverted waveforms could coexist within universal space, by it photon energy, radio waves, or atomic vibrations?

Cheers; /-Ian/@minusian

Re:OT: Question about waveforms (1)

Stolzy (2656399) | about 10 months ago | (#45089595)

(Apologies for the typos.)

Re:OT: Question about waveforms (4, Informative)

Yetihehe (971185) | about 10 months ago | (#45089627)

Yes. You have this effect in double slit experiment, there are places where waves cancel out and you have dark place. The problem is that it's almost impossible to generate an inverse waveform from source other than the one which generated your photon. Typically it's done by splitting one waveform.

Re:OT: Question about waveforms (2)

Antique Geekmeister (740220) | about 10 months ago | (#45089687)

Waveform "cancellation" is limited by a number of factors. There is always interference, and it takes as much energy to create the canceling waveform as the original, and unless the "inverted" waveform comes from precisely the same source, and orientation, as the original waveform, it cannot cancel the waveforms out everywhere, Moreover, if the canceling waveform is is being generated based on receiving the original waveform, simple lightspeed limitations preclude being able to completely detect and counter-generate a closely matching signal. For stable signals, a reflection counter generated signal is possible: holographic images rely on the light of the same color creating meaningful images based on the recorded interference patterns from the original holographic recording.

As you've noticed, sound cancellation can work well in a limited, well controlled environment (such as inside the ear of someone wearing noise cancelling headphones). But sound waves are also quite _long_ compared to most light waves, so producing them in phase to to cancel out another signal is relatively easy, and can be done dynamically. And there's the separate mater of "quantum" electromagnetic behavior. Energy is typically "quantized", existing in discreet bundles, for various reasons. You can think of it as sound coming from individual molecules of air, working together. For light, the very small wavelength makes it particularly noticeable, just as a stunningly high sound would have wavelengths on the order of the size of the space occupied by a single air molecule. At those frequencies, attempting to cancel the waves gets caught up in the behavior of individual "photons" of light or "molecules" of air, and controlling the behavior of the whole wave to get complete cancellation gets quite odd.

Re:OT: Question about waveforms (1)

hawkinspeter (831501) | about 10 months ago | (#45089943)

The photon is it's own anti-particle, so in theory you could have a photon meeting it's opposite and thus "cancel out". However, photons can exist in the same state in the same place and thus it's not easy to get a photon to interact with another photon. Typically, you can get an area where you won't detect the photons (think dark areas in double split experiments), but the photon/anti-photons will just pass through each other without interacting.

My idea... (0)

Anonymous Coward | about 10 months ago | (#45089617)

I immediately pictured a scientist who slowly raised his hand, while shouting: nnnnnnnnnnnnoooooooooooooooooooooooooooooooooooooooooooo!!!... as the wave function collapsed.

Re:My idea... (0)

Anonymous Coward | about 10 months ago | (#45089721)

And now i'm imagining that too! Funny stuff

Next year's Nobel? (1)

m.alessandrini (1587467) | about 10 months ago | (#45089659)

Definitely possible.

Information (4, Interesting)

Warbothong (905464) | about 10 months ago | (#45089665)

'Wavefunction collapse' is how the Copenhagen Interpretation 'explains' this phenomenon, but like many of its 'explanations' they don't provide a compelling reason for things to happen this way. Terms like 'measurement' go from a precise QM meaning (eg. matrix multiplication) to a vague, ambiguous meaning like 'a concious observer'. This leads to tenuous extrapolations and conclusions, like the distinguished position of observers, the inclusion of conciousness into the interpretation and all the quantum 'explanations' of consciousness which that has spawned.

Alternative interpretations are much less mysterious. For example, the Many Worlds Interpretation explains it via information transmission. A measument is anything which transmits information from inside the system to outside the system. When a system is measured, it doesn't 'collapse' into one state; rather, the thing which performed the measurement becomes part of the (now larger) system.

The Transactional Interpretation explains it as two-way communication between events at different times; a measurement is any event which propagates information back in time and a system is only in multiple states because the event which caused it is awaiting the information from the measurement.

Schrodinger's cat can be used to point out the difference:

The Copenhagen Interpretation says that the cat is literally both alive and dead at the same time in the box, then when a concious observer (a human) opens the box, the cat immediately becomes either alive or dead. This is very strange, for example why is a concious observer necessary?

The Many Worlds Interpretation says that the cat is literally both alive and dead at the same time in the box. Anything which interacts with it, for example photons of light, will become part of the system; ie. the light will literally be both a reflection of a living cat and a reflection of a dead cat. If those photons enter my eye then I will literally be both a human who has seen a living cat and a human who has seen a dead cat. If you talk to me, you will literally be a human who has talked to a human who has seen a living cat and a human who has talked to a human who has seen a dead cat, and so on. This propagation is exactly the flow of information between systems; there is nothing magical about humans, except that we happen to be human. A photon would get the same results as us if it repeated our experiments, with no 'concious observer' involved, except for the fact that photons don't tend to perform experiments (ie. the 'conciousness' part of Copenhagen is an anthropic bias).

Re:Information (5, Interesting)

alexgieg (948359) | about 10 months ago | (#45089865)

the 'conciousness' part of Copenhagen is an anthropic bias

It's worse than that. According to defenders of the Many-Worlds interpretation (of which I consider myself one), Copenhagen's collapse has several problems. Less Wrong's Eliezer Yudkowsky has written an extensive introduction to QM from the perspective of the Many-Worlds Interpretation [lesswrong.com] and as part of the series he's extensively criticized the collapse postulate, summarizing its problems [lesswrong.com] thus:

If collapse actually worked the way its adherents say it does, it would be:

1. The only non-linear [lesswrong.com] evolution in all of quantum mechanics.
2. The only non-unitary [lesswrong.com] evolution in all of quantum mechanics.
3. The only non-differentiable [lesswrong.com] (in fact, discontinuous) phenomenon in all of quantum mechanics.
4. The only phenomenon in all of quantum mechanics that is non-local [lesswrong.com] in the configuration space.
5. The only phenomenon in all of physics that violates CPT symmetry [lesswrong.com] .
6. The only phenomenon in all of physics that violates Liouville's Theorem [lesswrong.com] (has a many-to-one mapping from initial conditions to outcomes).
7. The only phenomenon in all of physics that is acausal / non-deterministic / inherently random [lesswrong.com] .
8. The only phenomenon in all of physics that is non-local in spacetime and propagates an influence faster than light [lesswrong.com] .

Given the above considerations, whatever the experiment detected is most certainly not collapse.

Re:Information (1)

wytcld (179112) | about 10 months ago | (#45090341)

The many worlds model's absurdity is right in its name. It's the belief that we have no choice, make no choices, but just randomly find ourselves in a world where certain things have happened, while duplicates of ourselves, at each instant where different things might happen, including our own different actions, find themselves inhabiting each of those many worlds. That's to say, the many worlds model requires that the illusion of choice model is the correct one for human agency. And not in the Newtonian sense where it's because there is only one causal destiny. Rather it's a claim that there's no one destiny, but we can't choose among the many destinies, and instead must realize them all, in an endless branching into infinite futures, in none of which will we ever have any real freedom, or real choice.

That contradicts everything we know about human psychology, as well as every possible evolutionary account for the advantage of consciousness. It contradicts evolution itself, since according to many worlds every possibility going forward is realized in one universe or another, even the possibilities which are, in a Darwinian sense, less fit.

Re:Information (0)

Anonymous Coward | about 10 months ago | (#45089871)

Or, phrased otherwise, the observer becomes correlated with the observed.

Re:Information (0)

Anonymous Coward | about 10 months ago | (#45089879)

I hate cats...

Re:Information (1)

clyde_cadiddlehopper (1052112) | about 10 months ago | (#45089957)

I just came here to become a person who has seen a video of Schrodinger's cat collapsing. Nothing to see here, move along.

Re:Information (1)

Shavano (2541114) | about 10 months ago | (#45090177)

Well stated. It's remarkable that so many physicists have adhered to the Copenhagen interpretation for so long, stating it as fact when explaining it to laymen and worse, to students of physics when in fact it is a subject of debate among prominent physicists and has been all along. The interpretation itself makes a lot of untestable claims and for that reason alone it ought to be regarded with great skepticism and no conclusions should be drawn from it.

I also find it remarkable that it's named for Copenhagen. There is or is not a lot of weed to be smoked there.

Re:Information (1)

omnichad (1198475) | about 10 months ago | (#45090281)

'Wavefunction collapse' is how the Copenhagen Interpretation 'explains' this phenomenon, but like many of its 'explanations' they don't provide a compelling reason for things to happen this way. Terms like 'measurement' go from a precise QM meaning (eg. matrix multiplication) to a vague, ambiguous meaning like 'a concious observer'. This leads to tenuous extrapolations and conclusions, like the distinguished position of observers, the inclusion of conciousness into the interpretation and all the quantum 'explanations' of consciousness which that has spawned.

If a tree falls in a forest and no one is around to hear it, does the wavefunction collapse to make a sound?

Re:Information (1)

nine-times (778537) | about 10 months ago | (#45090537)

Do you actually know what you're talking about, or have you just read too much science fiction? I don't remember the Copenhagen Interpretation being related to "consciousness", either in the requirement that an observer be "conscious" or in using quantum mechanics to explain consciousness. Are you sure that's not just some whacky interpretation of the Copenhagen Interpretation that people have come up with more recently, due to misunderstanding?

Re:Information (1)

ath1901 (1570281) | about 10 months ago | (#45090801)

I thought the main point of the copenhagen interpretation was the instrumentalist approach. That is, the mathematical description should not be considered a description of reality but just a tool for calculating probabilities of real events. So, these supposed issues with 'conscious observers' do not apply. There is no real wavefunction and no real collapse. It's just a mathematical description.

But, even if you take a realist approach to the standard QM theory and argue that the wavefunction is real, conscious observers are still not required. It is a well known and tested fact that you do not need a conscious observer to collapse a wavefunction. Take your classical double slit experiment, put a measuring device by one of the slits to force a collapse of the wavefunction (and thus no interference pattern). Now, put a piece of tape over your measuring devices display so no conscious observer can see it. The result doesn't change.

Yes, a philosopher or someone taking the collapse notion a bit too seriously would argue that the entire system (detector, double slits, measuring device etc) is in a mixed state until the observer checks the output on the detector but that is quite a stretch. (See the whole Schrodingers Cat debate)

All measuring devices are huge from a quantum mechanical standpoint. We can barely make calculations on large objects like molecules (and that with rather heavy approximations) and measuring devices typically consist of lots and lots of molecules. It is currently quite impossible to write down a quantum mechanical description of even a simple experiment with a simple measuring device. If we could, maybe we would see that the that the addition of a measuring device causes a mixed state to evolve into a pure state, just by the laws of QM. No conscious observers would then be necessary and the 'collapse' would be just a consequence of the theory. However, making those calculations is way too complicated and far from what we can currently do.

So, neither the instrumentalist or realist interpretation of standard QM theory requires conscious observers.

Heisenberg Compensators?! (0)

Anonymous Coward | about 10 months ago | (#45089689)

Beam me up!

Re:Heisenberg Compensators?! (0)

Anonymous Coward | about 10 months ago | (#45089731)

Sir! I know you are going to send me down! But sir I am afraid! I have never seen a female close hands! Only on pictures sir!

ACTIVATE DOWN BEAMING TRANSMITTER

Erwin Schrödinger (2)

Dialecticus (1433989) | about 10 months ago | (#45089699)

Do you realize what this means?! We can finally make a cat that's dead or alive to an arbitrary percentage!

Re:Erwin Schrödinger (0)

Anonymous Coward | about 10 months ago | (#45089787)

You mean a cat that's both dead and alive in an arbitrary ratio.

Re:Erwin Schrödinger (0)

Anonymous Coward | about 10 months ago | (#45089847)

[to Mills]
William Somerset: Put the gun down.

[throws down his own gun; to Somerset]
David Mills: I saw you with a box. What was in the box?

Erwin Schrödinger: Because I envy your normal life. It seems that envy is my sin.

William Somerset: Put the gun down David.

David Mills: No! What's in the box?

Re:Erwin Schrödinger (0)

Anonymous Coward | about 10 months ago | (#45090241)

But can we spin the cat round round, baby right round, like a record baby?

Collapse of a website (0)

Anonymous Coward | about 10 months ago | (#45089795)

I think instead, I just witnessed in real time the catastrophic collapse of a website due to the famous "slashdot effect", first theorized circa 1997.

Trivial kind of local collapse (4, Interesting)

Nightlight3 (248096) | about 10 months ago | (#45089913)

This is not the non-local collapse which some QM physicists (mystical school of thought) believe in. Everything in this experiment is local, the two superposed wave components which collapse into one are fully overlapped. Hence it is no more mysterious than your radio antenna collapsing superposed waves of thousands of radio stations striking it, into one component, that of a station you tuned in.

The real controversy is about existence of non-local collapse i.e. when two components and detectors are "far apart" (at space like distance), so that detection by detector D1 (supposedly) instantly collapses the remote field component causing the remote detector D2 to fail to detect it. Most recent experiment claiming to demonstrate such phenomenon with photon on a beam splitter actually cheated (see discussion here [physicsforums.com] ). In that claim they basically tweaked the timings on two coincidence circuits well out of manufacturer's specs so that they could never trigger D1 and D2 simultaneously.

Non-local collapse, which was never demonstrated empirically, does not follow from the Quantum Field Theory (discussion here [physicsforums.com] ) but is merely a hypothesis in the QM "measurement theory", which is the speculative, soft and fuzzy, part of the theory that has been debated among physicists, philosophers and mystics for nearly a century without getting anywhere so far.

Re:Trivial kind of local collapse (1)

RoccamOccam (953524) | about 10 months ago | (#45090121)

Thank you! I was wondering about this, because it seemed that knowing whether a non-local collapse had occurred, or not, would allow for FTL information exchange.

Re:Trivial kind of local collapse (0)

Anonymous Coward | about 10 months ago | (#45090361)

Sure. But how do you communicate that information? With another non-local collapse, which you can't tell has occurred without being informed of the fact?

Quantum communication is hampered by the fact that, even when entangling individual particles, you don't get to choose the state in which they become entangled. It's like trying to communicate using matched tubes of marbles, where you can guarantee that the sequence of marbles is the same, but you don't get to choose the sequence, and you don't know what it is until someone starts pulling the marbles out.

Yves Couder (1)

gr8_phk (621180) | about 10 months ago | (#45090877)

Are you familiar with the work of Yves Couder [youtube.com] ? Macroscopic Newtonian systems exhibiting features of quantum behavior. All this voodoo is probably just a lack of understanding.

Doesn't solve the original problem (1)

BitZtream (692029) | about 10 months ago | (#45090151)

This is silly. Taking a measurement of the microwaves that passed through it doesn't change that it was modified by the measurement. They're just using the excuse that the microwaves weren't theres, and then ignoring the fact that the microwaves were changing the process themselves.

The fact that the microwaves behaved differently is a direct result of their interaction with the wave function. Both were modified by the interaction.

They still didn't measure quantum collapse without effecting it, they're just ignoring the effect. They used microwaves to directly measure it, but just ignore that the microwaves passed through it.

Roll for SAN (1)

SuiteSisterMary (123932) | about 10 months ago | (#45090423)

You know in games like Call of Cthulu, or more germane, games like Delta Green or Cthulutech, where doing research into 'extra dimensional science' or whatever other terms they use to describe the eldritch magics and alien geometries, drives the researchers insane?

That's what quantum physics is like.

Dr Quantum - Double Slit Experiment - a video! (1)

Trax3001BBS (2368736) | about 10 months ago | (#45090459)

http://www.youtube.com/watch?v=DfPeprQ7oGc [youtube.com]

A quote from the comments (saves time):

jon manock 1 week ago
"this video is extremely misleading. the electron does not know it is being observed and decide to behave like a particle.
it is the electron interacting with the test equipment that collapses the wave function. consciousness has nothing to do with it."

Mistake (1)

gr8_phk (621180) | about 10 months ago | (#45090739)

You can not tell the difference between particles that are in a superposition of states and those that have "collapsed". If such a difference could be discerned then entangled pairs could be used for faster-than-light communication by modulating their "collapsedness". These guys are not dealing with particles but a somewhat larger system. Is it an example of macroscopic system exhibiting quantum behavior? If so, does it offer a non-magical explanation of the phenomena?
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