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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.
...about one and a half meters, or about five feet away for my metrically challenged Americans. At first, this humble journalist...
Man, what an ass. Sounds to me like a pompous buffon.
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.
Why not perpendicular, or skew? I think that differently oriented manifolds are being discriminated against!
When things get complex, multiply by the complex conjugate.
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?
Hawking describes this type of thing in A Brief History of Time. This is NOT proof of a paralell universe, it's proof that light travels as a wave as well as a particle.
LK
"Hi. This is my friend, Jack Shit, and you don't know him." - Lord Kano
This kind of pseudoscientific articles are one of the worst things on the internet!
This is a classic optics experiment to show that light has wave properties, and it has NOTHING to do with parallell universes. It is all explained here:
diffraction
And if you want to show any quantum mechanical effects you need to make sure that only one photon leaves the laser at any given moment, and that is not happening here.
Sam Sachdev writes "David Deutsch, a physcicist at Oxford, has designed a home test for red laser pointers. Using a pin, a parallel universe, a piece of paper, and a relatively dark room, he claims that the results from this experiment confirm the existence of laser pointers." Okay, so it may not really be proof of laser pointers, but it's a fun trick to try with a parallel universe nonetheless.
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.
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.
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 this, and everything changed! I'm fat! My beautiful wife is gone! My beautiful aircar is gone! All of my stuff is crammed into this stupid apartment!
I can't even find a link to the nearest spaceport on Google!
How do I get back home?!?!?!?!?!
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.
My parallel self tried it and said that it didn't work.
___
It's the end of my comment as I know it and I feel fine.
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.)
The "parallel universe" part comes in to explain why it still works if you fire single photons, but since you can't fire single photons (or easily check the results if you could), this isn't really a "home test" of any use.
The fact that single photons can make a diffraction pattern, seemingly interfering with themselves, is a truly weird feature of quantum mechanics (but then, I repeat myself -- quantum mechanics is always truly weird!). And one of the explanations proposed is that light in parallel universes is somehow causing the interference with the single photons in this universe.
Another explanation is that light sometimes acts as a particle, and sometimes as a wave, and when you detect a single photon coming through a slit, you are forcing that photon to act like a particle, and it will not throw a diffraction pattern; but if there is no measurement to decide which slit the photon passed through, the light can act as a wave instead of a particle, and can have an interference pattern.
http://www.starlight-pub.com/UnitNatureofMatter/P
This page lists various explanations of why the single-photon two-slit experiment behaves as it does. One of the explanations is the parallel-universes one.
http://members.aol.com/jmtsgibbs/TwoSlit.htm
Here's just the part with the "Many-Worlds Interpretation":
steveha
lf(1): it's like ls(1) but sorts filenames by extension, tersely
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.
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.
and so, out of guilt and self-loathing, it hides itself from the observer?
Firstly, as others have pointed out, this is essencially the double slit experiment. In this case, because he's just using laser light, this simply demonstrates the interference of waves.
More interesting results come from when you pass through single electrons or photons one at a time, and they show the same behaviour, but this experiment does not demonstrate this. Nor is the only explanation for this to assume parallel universes. The so-called "Many Worlds" theory.
In fact, according to this, the Many Worlds theory has been invalidated by a recent experiment.
So not only does this laser-pen experiment not prove the existence of parallel universes, but the Many Worlds explanation of the phenomenon has been potentially been already disproven.
I did the experiment and have confirmed the results! Parallel universes exist, and I think David Deutsch is a genius! I have registered www.daviddeutsch.com and I will be building a shrine site to David Deutsch this week, so check back often! If there are people in this parallel universe, we need to contact them!!! Does anyone know if the people you talk to on an Ouija board are from this parallel universe?
There isn't really anything mystical with the "observer", after all, it's only a way of talking about an interfering particle, isn't it?
As I understood it, superposition of states is the way it's ususally seen (and described as), but some physicists want to keep things more deterministic, and introduce parallel (deterministic) universes instead of a single indeterministic one.
xkcd is not in the sudoers file. This incident will be reported.
Ok, this proves quantum theory. Saying that parralel universes therefore follow is either gross oversimplification or just forcing your metaphysical opinions of a physical theory on others. And yes, Young's double slits, old news. Also, this doesn't show that light is a wave. This demonstrates that a photon can be placed in superposition. This experiment has also been done with electron beams, whole atoms, and (IIRC) C60 (buckminsterfullerene), and they make interference paterns. Now atoms are definitely particles.
# cat
Damn, my RAM is full of llamas.
this is what is causing the interference, "[W]hen a photon passes through one of four slits, some shadow photons pass through the other three slits." The shadow protons, then, are blocking the tangible protons, causing only three shadow slits.
... so what do I know? Maybe it does make sense ... but Parallel Universes? I don't know .. sounds like he's reaching for an answer to explain the unobservable. Given time, this ?theory? of his will be proven wrong. You know how it is... the world is flat, the sound barrier can never be broken, 640k is enough for anything, etc...
These shadow protons form a parallel universe.
I'm reminded of a Star Trek: TNG episode where Data went down to some planet to collect radioactive rocks. Somehow he short circuited (or whatever - I'm not much of a Star Trek fan) and "forgot" who he was and ended up in this small village full of people that were several centuries behind the human race.
While in this village, Data sat at a table listening to a teacher explain to her student what the various forms of matter were. In one of her explanations (and you star trek geeks will have to forgive me if I'm getting the details wrong here) but she said that fire was "inside" of wood and that it could only be released by heating it up... Data interjected and said that he felt like her conclusion had to be wrong for such and such reason. And throughout the episode he demonstrates a couple of other (obvious to us) things that these unevolved people are confused about.
My point is - this guy's explanation sounds like a conclusion drawn from a limited understanding of how things really are. But IANAQP (I am not a quantum physicist)
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.
But the observer is a passive receptor (in our case). I entirely sympathise with the objection - why is a human's retina the defining absorber, whereas those photons that strike other absorbing surfaces do not collapse the wave function.
As it happens I am a super-Copenhagen believer, that is, our function, as conscious entities, is to observe the many possible universes and 'select' the real one.
This defines consciousness, by the way.
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.
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
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).
'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?
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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