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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.
Oh yea, it was that one episode of McGyver.
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.
---- El diablo esta en mis pantalones! Mire, mire!
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."
i tried it and the laser turned 90 degress midair
does that mean i have a perpendicular universe?
Detection of tachyons now possible via the usage of duck tape, scissors, a wooden spoon, and a very unhappy hamster.
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?
You have understood nothing. The phenomenon is real and one of the strangest and most spooky things in physics. It shows that it it possible to get a particle (in this case a photon) to interfere with itself.
The only question is how you interpret it. The first interpretation, created by Einstein, Bohr and other dignitaries of the time, was the "Copenhagen Interpretation" which requires an "observer".
The "Many-worlds interpretation", first thought of in the late fifties gets rid of the need for a mystical observer by introducing parallell universes, where entangled particles can still interfere with each other.
This interpretation is championed by many of the leading physicists. For example Deutsch and Murray Gell-Mann.
I believe Feynman has a strange third interpretation involving particles travelling backwards in time, that cancel out the waves of forward travelling particles at specific points in space-time.
Opinions stated are mine and do not reflect those of the Illuminati
Absolutely.
He is talking about the classical double slit experiment. The results of that experiment are correctly predicted by quantum physics because you need to treat photons as waves and not as particles here.
The author however wants to explain the results treating the photons as particles only. I must admit I have no idea why this leads him to the parallel universe theory.
In my opinion that theory is not needed here as we already have an excellent model (the quantum physics) that predicts those results extremely exactly. We must not forget that quantum theory (and its application in particle physics) is the most accurate theory / model in the world. No other theory other than quantum theory matches as exactly with the experimental results (up to 10 to the power of -9)!
When I tried this experement I ended up with a 3D holographic image of the words "There is no alternet universe"
and a few moments later someone whispered
"If you try that again we'll eat your soul"
So there is no alternet universe...
Ok mister spooky voice you can stop making my walls bleed. And could you remove the chains from the door? I will NOT be entering that hole in the wall ok?
I don't actually exist.
Second of all, he credits David Deutsch with an idea that most certainly is not his. Both the notion of wave functions (what this article is talking about) and the idea that this somehow relates to parallel universes are older than I am.
This is not a revolutionary idea, and it is not really a controversial one either, as the author of the article seems to indicate. This is just one explanation of a curious quantum mechanical effect. There are other explanations, and they all describe what happens quite accurately. They may each have their own proponents, but really none of them is wrong--they are just different interpretations.
I generally do not like griping, but this write up is positively abysmal. It is no offense to David Deutsch--I am sure he is a quite competent individual. But I do not think the author of this paper actually read his book. It sounds too much like the BS I would string together from reading the first few chapters and the epilogue when I had a book assignment in schoool.
Go here for a decent, intuitive, layman's introduction to various quantum mechanical oddities.
When things get complex, multiply by the complex conjugate.
I tried the experiment myself, and Dr. Deutsch is right! Through the holes, I saw images from many parallel universes, worlds in which Columbus discovered Europe, Lincoln shot President Booth, and Germany and Japan saved the world from Nazi America and Fascist Britain in WWII. (However, Michael Jackson is a disfigured weirdo pervert in every parallel world. Must be a fundamental physical law, like the speed of light.)
Well, how do you know if you live in such a "multiverse"? The answer was proposed by Max Tegmark just a few years back:
Take a gun, put it to your head, and pull the trigger. Repeat several times. If the multiverse model is correct, then your "self" will continue to exist only in those universes where the gun does not fire. So if you try and pull it a bunch of times and nothing happens, you must be one of the many parallel yous who happens to live in a universe where, in spite of probability, the gun did not fire.
Of course, I would not recommend trying it. If the MWI is correct, well, then in another universe you already have tried.
When things get complex, multiply by the complex conjugate.
Are you sure?
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.
Another point: regarding your link to the blog, I mention the following comment from Physics Forums: The blog did not indicate two things: (1) that there's no references to the Afshar experiment and (2) that it is having problems in the refereeing stage. In fact, unconfirmed reports have indicated that the Afshar experiment report that was uploaded to the e-print archive was removed, something that is unheard of for arXiv. Until peer review of this supposed invalidation, lack of skepticism is silly.
"Politicians and diapers must be changed often, and for the same reason."
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".
Experiments have shown that subatomic particles act very funny when you try to describe or figure them out. Basically, these particles act like particles half the time, and like waves the other half of the time, but never both at the same time. Certain well known experiments (like the banding described in the article, which are due to wave interference of light particles) have shown that particles can somehow seem to act is if they are in multiple places at once, yet they cannot be observed in multiple places at once. This has led a lot of physicists to surmise that there are 'multiple parallel universes' where that exist simultaneously. The rationale is that since the inherent particles that make up our universe are in multiple states at the same time, these inherently MPD (multiple personality disorder) particles make up a sort of multi-verse that exists at the same time in different states, thereby creating different realities/parallel universes.
...and I will reiterate, IANAQP, but it seems to me that there is a lot of going from A, B, C to X, Y, Z with nothing in the middle with that notion. We cant observe the quantum weirdness at our human-sized perceivable universe, and to assume that this quantum weirdness can cause other realities where GWBush is in Mensa seems to be a far step of logic.
If there are any quantum experts out there, and see a problem with my reasoning, or just want to educate the ignorant masses (please leave out the math, its just boring), I urge you to help.
--J
Beer, now there's a temporary solution -- Homer Jay S.
Exactly. It's the Woody Allen phenomenon.
SharkJumper
(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).
IAAQP, and while I've not read this man's book, I'd be skeptical. Most physicists subscribe to the "Copenhagen" interpretation of quantum mechanics, which does not deal with parallel universes. The so-called "many-universe" theory has its followers but doesn't get much attention, for one reason: introducing the extra idea of multiple universes doesn't add anything to the descriptive power of the theory.
Before quantum theory was developed, most phenomena in nature were considered to be either particles or waves. This classification system broke down when particles were shown to diffract and waves were shown to be quantized. So nothing is really particle or wave, but everything has a particle or wave nature.
The canonical example is electron diffraction: shine a beam of electrons through two slits, and get an interference pattern on your photographic plate. Woo. Repeat with one electron at a time, recording each result.... and you still get an interference pattern. This presents a problem: each electron must have gone through both slits and interfered with itself. On the other hand, you can never measure the electron to be in two places at once, so we need to construct a third option. This is the idea of a superposition state: the electron is in a superposition of places (again, not actually "in" them); this superposition has wavelike properties and can interfere. When a measurement is made (by the photographic plate) the superposition "collapses" to one location.
This is where many-universe theory (to my understanding) comes in: how does the particle know which state to collapse to? Copenhagen Qm says it's random, but weighted by the superposition; i.e. quantum mechanics predicts probabilities only. Many-universe theory says that when that collapse occurs, the universe splits into a bunch of new ones, one for each outcome of the measurement. I've not yet read a good explanation (anyone have a link to one? I'd love to) of why measurement (that is, a phase-randomizing interaction with a larger system) should create a new universe.
Anyway, I hope this helps! If you are curious about QM, there's an inexpensive book by Isham that has really wonderful discussion (and even mentions many-universe). Feynman's book "QED" takes his path-integral approach and is a great layman's introduction; just don't try solving any problems with that method later (the math is rough).