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The Home Parallel Universe Test
Sam Sachdev writes "David Deutsch, a physcicist at Oxford, has designed a home test for parallel universes. Using a pin, a red laser pointer, a piece of paper, and a relatively dark room, he claims that the results from this experiment confirm the existence of parallel universes." Okay, so it may not really be proof of parallel universes, but it's a fun trick to try with a laser pointer nonetheless.
Isn't this the same old double-slit experiment, just slightly modified? Perhaps this is new to some people, but anyone who's had the slightest interest in quantum mechanics or parallel universes should have heard of this by now.
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I thought the double slit experiment was intended to show that light behaved as both a particle and a wave.
"Come on, let's go drink till we can't feel feelings anymore."
IANAP, but doesn't this simply demonstrate wave interference? as in:
u ng .htm
http://www.cavendishscience.org/phys/tyoung/tyo
I'm no physicist, but the article talks about photons and their properties, then mid sentence and afterwards begins referring to them as protons and THEIR properties, then goes on with a description of some photon/proton hybrid logic
Is this a joke article?
Old experiment, old result, new conclusion. Bad science. Poor writing.
Why this is suspicious: It seems a little strange that only _one_ source is cited throughout the article, david deutsch. False information by third paragraph: First, a red laser pointer is needed. I found one at Radio Shack for $19, not including the triple A batteries that were needed. The red color of the laser pointer is important. The red light, unlike the white light of a flashlight, which is a composite of many colors, doesn't fray as white light does. The red light, specifically, of the laser pointer casts more specific shadows - which is what this experiment does. A flashlight, according to Deutsch, can probably be substituted. A filter, however, is going to have to be placed over the white beam. The filter, can only be red colored glass; paper or any other filter won't work. Yes, a laser is needed, but not because it is red, in fact any color laser should work, red is just the cheapest. The reason for a laser is that it provides coherent light, that is all the light that is emited is in phase. This is necsessary for the interference. Sachdev tries to explain the interference soley in terms of particles, when in fact the light is behaving as a wave. He is entirely neglecting the wave-particle dualty, and resorts to parrallel universes to explain it in terms of particles.
Junk science is everywhere. This, though, is the first time I've ever seen something along the lines of string theory's extra dimensions being "proven" by interference of waves.
Is there any way to mod down the fool who wrote the article?
What a bunch of unintelligible nonsense. I'm sure David Deutsch would explain this differently. Whatever he told the author of the article has been lost somewhere. Probably in the vacuous head of the author. He doesn't mention how light behaves as particles AND waves at the same time. He talks about "shadows" going dark. In fact, when I was done reading the article I wasn't sure what he meant by his use of the word "shadow" at all. The writer did a terrible job of explaining what's going on in this experiment and what it's supposed to represent.
Time, I guess, to DTFE.
Actually, protons are subatomic particles usually found in the nuclei of atoms. Maybe you mean photons?
This is a very old experiment, and a well-known phenomenon. It was even one of the answers on slashdot's poll for favourite physics experiment (and my personal favourite).
Even the idea that it is proof of parallel universes is not original. Michael Crichton made that claim in his book Timeline. It's an excellent book (despite the horrible movie loosely based on it), but it is fiction.
Jason
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"David Deutsch, using an experimentally confirmed prediction from quantum theory, believes that what's causing the interference are shadow photons." Oh yeah, that's what experiments do, alright. They confirm theories. Good grief. Theoretical physicists need to be beaten about the head and shoulders with slide rules by engineers, probably on a monthly basis.
This is just a version of the classic double-slit experiment of quantum mechanics.
Deutch believes in multiple universes. He uses this belief to explain the results, but typically for Deutch he says the results prove his belief, which is nonsense. There are many other explanations and one of the strangest aspects of quantum mechanics is that there is probably no way to say which explanation is right. Some of the other explanations are equally weird: the Copenhagen interpretation says that particles only 'collapse' into definite positions when something looks at them. The Transactional interpretation (my favourite) explains the results by assuming that particles are continually interacting back and forth in time. Other ideas include the suggestion that quantum states collapse into what we see when things get large enough for gravity to be significant (to put it simply).
Of course, the most sensible interpretation is to take the scientifically humble attitude and say that we don't fully understand what is going on and can't explain it, rather than to arrogantly assume all results 'prove' your personal metaphysical beliefs.
A photon isn't a particle, it isn't a wave. It's a photon. So many people don't understand that.
So when a bunch of photons show up as an interference pattern, they think of it as waves and the model produces accurate and useful results. When people knock electrons off atoms with gamma rays, they think of the photons as particles and the model produces accurate and useful results. When the two models come together, people have the hardest time understanding it because they forgot the most elementary rule of models:
ALL MODELS ARE WRONG.
As I understand it, under the standard model, we figure out if a photon interacts with another particle by integrating over the set of all possible paths the photon can take in the meantime, producing a probability. That seems like a pretty sound model to me. Does this model require more than one photon to explain diffraction? Nope. Does it talk about waves and interference? Nope. It doesn't mention parallel universes either. This is the model that scientists started using when they realized that both the particle and the wave models were not only wrong, but they didn't always produce useful results.
The problem I have with the claim that this is proof of parallel universes is that parallel universes doesn't add anything to the existing theory. Now, if the parallel universe theory were to predict something disagreeing with the standard model, anything at all whatsoever, it would be useful. However, as it stands, I see the theory as just a more complicated explanation of the standard model. It may be true, but it doesn't seem useful, and usefulness is the only desirable trait in a model.
No scientist understands the laws of the universe, scientists don't even agree on the laws. They don't agree on string theory, on the existance of black holes, on the fate of the universe, on the presense of dark matter, or interpretation of quantum mechanics. If anyone were to ask me about any of those, I would give a resounding maybe. Heck, there are scientists proposing revisions of Newton's law F = m*a to explain discrepancies in galactic rotation.
I just get sick of scientists peddling useless but imaginative models to the public like this. That's what philosophers / fiction writers are for.
A human retian is not the defining absorber. Interaction with any macroscopic system collapses the wavefunction. This is why if you run the two-slit experiment but put a detector by each slit to watch for which slit the photon passes through, you don't get an interference pattern. The interference from the macroscopic detector at the slits collapses the wavefunction. Consciousness does not enter into it, that's just pseudo-mystical nonsense.
Good to see people describing the quantum phenomenons as 'spooky'. Really. People tend to believe that everything's solved in physics. One has to keep in mind that physics only build *models of reality*.
Of course, in daily physics speak, one talks about 'the electrons that hit the surface' etc. because there is a underlying theory which describes most of the experiments with sufficient precision. Daily physics is simply more like engineering than thinking about the world itself.
But electron's are only human-invented concepts. Very successfull concepts, indeed. But only concepts. Maybe they're 'really resonances of some weird field' yet to be discovered. But what are resonances and 'this weird field'? They're also invented concepts. Concepts to aid 'understanding'.
Many of my fellows (I'm studying physics) just believe they're electrons which properties and formulas to describe them. I don't. I take them as always incomplete, yet successful and helpful models of reality. Maybe this is just an arrogant statement and my 'open-mindedness' now brands me a crackpot to be modded down.
But I am no crackpot. I don't believe in UFOs and stuff.
Regarding the 'multiverses': IMHO, one very important question remains: How you as yourself evolve in this multiverse. What decides which part you take in the multiverse? Why is it that you only see one universe, that you only exist in one universe? What decices where you/your conscience goes? Maybe this is the free will? I don't know but this bothers me.
See, this is what happens when you apply "interpretation" to science.
Quantum Physics is the single most successful theory in the history of science.
The interpretation of Quantum Physics is the single least scientific endeavour known to man.
It was fine for great physicists to propose these interpretations, but for anyone to accept them as "real", or to say one interpretation is more "correct" than another, is wrong-headed. What gets me is the people who then springboard off their favourite interpretation to make wild sweeping extrapolations with no scientific backing whatsoever.
Like, "this defines consciousness".
The experiment sounds interesting, but I would never, never, never read anything this guy writes. It sounds like he has a very simple experiment that could be explained in about a paragraph and we had to make it hundreds of words. There is so much filler and useless extra language that I wanted to scream. Take a piece of paper with 2 holes in it. Shine a laser pointer thru it. Look at the wall. Put two more holes in it. Look at the wall again. Now I will explain the phenomenon.... There, I just rewrote his whole article. Argh!!!!!!
Cum catapultae proscriptae erunt tum soli proscripti catapultas habebunt
The computer in front of you is also nothing but a concept. It's just your bain's interpretation of the data coming through your senses. It's part of your brain's model of reality. Yet you'd surely call the computer real. Why? Because your brain's model works for it. The computer behaves as if it were really such a thing as your brain's model says.
Now, for electrons, it's the same: In all experiments so far they behave as if they were exactly what the theory describes. And therefore they are real, in the same sense as the computer in front of you is real.
The Tao of math: The numbers you can count are not the real numbers.
Exactly - from the last paragraph of the article.
It should be added that most physicists disagree with Deutsch's conclusion that what is detected in this experiment is another universe. For brevity's sake, the argument against can be summarized as, there is something interfering with the light in this experiment, why does it have to be a parallel universe? Why can't it be just be left to something that we don't yet understand?
True. But the distinction I think he's trying to describe is like comparing Newtonian physics and Einsteinian physics. For most everyday stuff involving objects we can see and speeds easily measured, Newtonian physics work well (e.g. using F=ma to measure acceleration of a car). But as you approach the speed of light or supermassive objects, Newtonian physics' inaccuracies appear. The more extreme the conditions are, simpler models show their inadequacies and a more detailed accurate model is constructed. The same thing applies with electrons -- the basic model of an electron works reasonably well for things such as building simple electronic circuits and maybe particle collisions (I can't really say for sure, IANAP), but as more extreme conditions are explored, a more detailed model may be needed to explain electron behavior. Maybe it's like a fractal -- the closer you look at the edges, the more details that appear.
"No one likes working in a hamster wheel, and your shop smells of cedar shavings from here." - TaleSpinner
Then you've heard of the Institute of Physics' Dirac Prize, right?
As I read this he's calling the light that passes through the holes "shadows" that disappear by going dark.
--
As a matter of fact, I am a lawyer. But I play an actor on TV.
(F = ma ran into a couple of problems a while back. Some guy named Albert studied the results of some experiments by some other guys named Michaelson and Morley, and decided that at high speeds, the concepts "m" and "a" started to get a little freaky. "d" and "t" were found to be pretty dicey as well.)
The parent post is right: quantum mechanics is one of the most successful theories in the history of science. By successful, I mean that it (a) accurately predicted measurements that were not explainable by previous theories, (b) has not predicted any results that are demonstrably incorrect, and (c) did all of this with a fairly simple (minimal) formulation.
Those three statements can be made about any solid theory, but QM has one unique characteristic. Unlike (say) Mendellian genetics, which challenges us with the difficult (but tractable) problem of "How did a biochemical mechanism for inheritence of traits ever come to be?", QM challenges us with "Why does the universe behave in a way which is contrary to our fundamental sense of reality?" This is not a knock against the theory, though. It just raises the deeper question: "Why should we assume that *our* fundamental sense of reality f-ing matters?" Despite almost a century of incomplete attempts to understand what quantum mechanics "means", the theory itself keeps on keepin' on - unfailingly accurate in its predictions, blithely indifferent to its metaphysical ramifications.
A different post in this thread makes the key point for grasping the various interpretations of QM: they are just *interpretations*. They have no bearing on what is "real" or "not real". All that is real (AFAWCT) is that the predictions of QM are accurate. Whether that means phantom universes, wave-particle duality, or little green men, is really of no importance until one of those interpretations leads to novel, verifiable predictions.
The article was not only an atrocious and pompous bit of writing, it was bad reporting. To represent this scientist's thesis as "novel" or even "scientific" just shows that the author doesn't know beans about the history of quantum physics.
Disclaimer: IWOAPUTDCB (I was only a physicist until the Dot-com boom).
'Fraid not, chief. Water waves are vast assemblages. Individual photons are ... well ... individual photons. The double slit experiment works when the photons are fired through the slits one at a time. This, if you properly grok it, is FUCKING WEIRD.
Is it fascism yet?
You have understood nothing. The phenomenon is real and one of the strangest and most spooky things in physics
The poster to whom you are replying phrased his comment flippantly, but his criticism is correct. Deutsch's argument is, "I can't explain this, therefore it is inexplicable without introducing parallel universes". The conclusion simply does not follow from the premise.
Compare, "I can't think of any way in which you could build a ship out of materials that are heavier than water, therefore ships made of iron are impossible". An argument that was taken seriously once. Or Kant's argument that space and time were both (separately) absolute, because he couldn't imagine otherwise.
The thing that always made Schrödingers cat seird to me is that the cat is not counted as an observer of itself. I may not have seen if the cat is dead or not, but the cat sure has. So hasn't it collapsed the wave function? Would it be different if it was a human in the box?
Ah, but what if no one was looking at the detectors? Could they exist in a superposition? That's the paradox of Schrodinger's Cat.
And what exactly is a "macroscopic" system? Is it not composed of quantum particles?
Collapsing the wave function when it interacts with a "macroscopic" observer is no more of an explanation than interaction with a "conscious" observer: neither "macroscopic" nor "conscious" are properties that are defined within quantum theory.
Bringing consciousness back into it at least brings us back to an oft-forgotten principle: all physical law is simply a means of grouping and prediciting observations that we (conscious observers) make about the objective universe. Any interpretation past that point is dancing on thin ice.
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No "trick" about it actually. The mathematics are
quite sound. As well Feynman came up with the Feynman diagrams and eventually the calculations to ground them in but the idea of antiparticles as particles moving backwards in time comes from Dirac. Feynman simply took it to a "logical" conclusion and using his different "tool box" developed a completely different(but equivalent) way of looking at quantum mechanics.