The Home Parallel Universe Test 754
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.
Polarized Lenses (Score:1, Interesting)
Re:Fabric of Reality?? (Score:3, Interesting)
A horizontally and a vertically polarized filter block out all light.
But put a 45 degree diagonally polarized filter in between, and suddenly 1/8th of your original light source is going through.
Re:Fabric of Reality?? (Score:2, Interesting)
Re:Isn't this just the double-slit experiment? (Score:5, Interesting)
In other words, they're using the term "parallel universe" to get people to read this. They found a neat effect with photons, yes. Might as well just call it a Terroristic Particle Exploitation, and then maybe the real media will examine it at that point. Nothing to see here, move along.
Incompetent drivel (Score:5, Interesting)
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 [higgo.com] for a decent, intuitive, layman's introduction to various quantum mechanical oddities.
Re:Isn't this just the double-slit experiment? (Score:5, Interesting)
He believes the many-worlds interpretation of quantum mechanics adamantly, and thinks that any other interpretation is, if not outright wrong, not a useful frame of mind to understand QM.
I am also a many-worlds person, as are many other physicsts I know, but I also know many very smart quantum physicicst who are not, and I am not willing to say they are wrong (yet).
I think a historical analogy might be appropriate: Back in the day. there was substantial scientific contention over whether the sun revolved around the earth or vice versa (I am not considering the religious contention -- for a while the scientific evidence was not sufficiently clear). You see, you could reproduce all the observable motion of the planets in the geo-centric model using finer and finer epicycles. So, planets would revolve the earth, and had wobbles in their orbits that faithfully represented their entire movement patterns. Or, you could adopt a helio-centric model, in which all the retrograde motion and other strange behavior cleanly fell out of the equations. You could do the math either way, but in retrospect, the helio-centric model is a much better "interpretation" of the data than the geo-centric model, because it is useful for figuring out all sorts of other things, like gravity and conservation of momentum.
Deutcsh feels similarly about the many-worlds interpretation. But as I said, among quantum physicsts you will find the whole range of people with different levels of commitment to different theories. or interpretations.
Re:Wavicles are fun (Score:3, Interesting)
True.
However, we don't understand how it works. Quantum theory is a bunch of constants and equations, and it all works but we don't understand why. The "many-worlds interpretation" of quantum mechanics suggests that parallel universes have something to do with how quantum mechanics works.
P.S. We also don't understand why quantum mechanics rules apply at very small scales, but very different rules apply at larger scales. (A photon can seem to go through two slits at once, but you won't get a baseball to do that trick, or even a really tiny speck of dust.)
steveha
Re:Interesting way to test for the MWI (Score:1, Interesting)
Even the other universes have laws. (I'm vaguely familiar with the theory and I get what you're saying, though.)
Question: according to the theory, where was the first split? Before or after the creation of the first observer?
two-slit experiment (Score:3, Interesting)
"An interesting theory trying to explain this seemingly inexplicable result, is by taking the hypothetical possibility that the bands are created by photons that exceed the speed of light. Only when they revert to another (visible) quantummechanical state (by hitting the wall, for instance) do they become noticable.
This is not impossible, because, contrary to what most ppl think, lightspeed is in fact an average; within one beam, there can be photons that are moving slightly slower, and photons that move slightly faster then the speed of light.
This, however, leads to the conclusion that those particular photons come from - at least potentially - another time or space. So, the film 'paycheck' might not be complete bullocks after all (though it's doubtfull we are ever going to be able to create a usefull 'time-viewing' tool out of it).
Then again, never say never, as Bill Gates with his '640K is enough for everyone' can vow.
The theory about another 'space', in contrast, leads us to the possibility that those photons actually come from parallell universes. It seems SF, but it are, in effect, valid scientific hypotheses which deserve further investigation.
After all, apart from these theories, there *is* no explication for the result of that experiment."
While I have had a lot of criticism for the 'faster then light' therory (though I didn't invent it, and it *was* proposed as a hypothesis), the 'parallel universes' hypothesis is a bit more well known, it would seem.
Re:Fabric of Reality?? (Score:3, Interesting)
I read "Schrodinger's Kittens" recently (so I'm obviously an expert ;) and I couldn't help but feel that photons sounded like they were riding a wave. The wave passes through both slits, but the thing we measure as a photon only goes through one. Since the wave is now interfering with itself, it affects where the photon lands. I'm sure I'm talking out of my arse, but I've always wanted to make this comment and get people's responses...
Re:Since I can't see air it must be another univer (Score:4, Interesting)
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.
Re:Fabric of Reality?? (Score:3, Interesting)
Send a single photon towards the slits, record which slit it passes through, and then cover up the slit that it passed through so that there is now only one slit. In some parallel universes the slit that we covered up will be open because the original photon would have gone through the other slit (which I believe is the fundamental argument behind the parallel universe explanation) so we should still experience an interference pattern from one slit if the parallel universes exist and if we don't see an interference pattern then the parallel universe explanation is probably false. Am I onto something here or am I completely off base?
Re:Fabric of Reality?? (Score:5, Interesting)
Well, That's not completely correct. You only get the same pattern on the wall if you plot the statistical distribution for the photons. Although SINGLE photon won't make an interesting interference pattern, the probability of where the photon hits follows that pattern (thus a statistical record of many photons will produce the image).
I'm just preemptively clairifying this point, since this confused me years ago when I first learned about the experiment. :-)
Actually it was on Star Trek: TNG (Score:5, Interesting)
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)
Re:Fabric of Reality?? (Score:2, Interesting)
I understand that non-deterministic behaviour scares a lot of people, but Occam's Razor surely rules out inventing an infinite number of universes diverging from every single even in the whole of space and time just to explain a simple experiment with a laser that has other reasonable mathematical and physical explanations.
Re:Since I can't see air it must be another univer (Score:5, Interesting)
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.
Re:Isn't this just the double-slit experiment? (Score:3, Interesting)
If you're a physicist, perhaps you can answer a question that has been puzzling me for some time when reading about the slit experiment: what exactly is 'a measurement'? Is there a scientific definition? For example, if something detects the photon, but then discards the information does it still count as a measurement (and affect the intereference pattern)?
Entanglement beats the diffraction limit (Score:2, Interesting)
This is the real scientific deal, if you want to entanlge your mind with quantum mechanics and double slits experiments.
I'm too lame to have a sig.
Re:Isn't this just the double-slit experiment? (Score:3, Interesting)
Considering that this experiment was done decades ago, you'd think you could go to Radio Shack and buy a junior double-slit experiment kit for $29. I believe the experiment, because a PhD physicist co-worker of mine vouched for it, but if not for him, I'd say the whole thing is a hoax. If it was done in the 50's with primitive technology, why isn't this experiment repeated more often? Other than this laser experiment, I've only seen pictures of a wooden box with a tube that looked like something built in the Victorian era, and charts that show what it's supposed to do. With so much pseudoscience and hogwash floating around, they can't expect us to just take their word for it. Show us!
BTW, I'm not asking you, I just needed to interject this comment amongst physicists, hoping that someone will say "moron, just go here and you can order a experiment kit for fifty bucks".
Re:Isn't this just the double-slit experiment? (Score:5, Interesting)
Measurement is a physical process. Despite what many people have said in the past it, has nothing to do with what you are aware of. If you detected a photon, then you did something physical to collapse the wave function. So it doesn't matter if you throw the data away or not, the physical interaction still occured.
So in other words, if you are familiar with Shroedinger's cat paradox: The cat in the box will start to rot and stink or it won't. (given food, air, water
If I had to make a definition, I would say that measurement is a physical process between a macroscopic "classical" system and a quantum superposition of states. The interaction is in such a way that the superposition is collapsed to a single state and triggers the macroscopic measuring device into giving us a certain result - that result corresponding to what state the quantum system was collapsed to. All this with the addendum that the measuring device should be "fair" and give us a probabilities that are not modified by the measuring.
Measurement is not well understood by everyone in the community. This is probably because measurement as performed mathematically is retartedly simple. But that is a gross oversimplification of how measurement really occurs in nature. When you do the calculation for a measurement you don't even consider the interaction between the device and the system, you just assume it all works perfectly.
And even for the best among us, measurement isn't completely understood. There are serious issues with measurement dealing with time and relativity. Somebody might know these answers, but it isn't me.
Re:Isn't this just the double-slit experiment? (Score:3, Interesting)
Re: Isn't this just the double-slit experiment? (Score:5, Interesting)
Because light isn't a standard classical wave -- it's made up of discrete particles. But you get the standard wave diffraction pattern built up, even if you only let through one photon at a time...
It's the fact that light is made up of discrete particles and yet can still behave like a wave, that's like nothing we see in the large-scale world, and that leads directly to QM.
I believe the explanation for the double-slit experiment in the many-worlds interpretation of QM boils down to the photon interfering with all the corresponding photons in all the other universes...
hmm (Score:1, Interesting)
-cory
Re:Since I can't see air it must be another univer (Score:3, Interesting)
It's rather interesting that after his work on relativity some people asked him about his religious beliefs to which he replied that they did not matter, but ultimately they did matter. Einstein later said that his religious beliefs were losely based on those of Spinoza. Basically Spinoza said that the universe is itself a part of God (this is an oversimplification though). To Einstein, if the universe is non-deterministic, then God must be capricious and random, which is something that Einstein could not accept.
Einstein believed that the probabilities that arise in quantum mechanics must result from incomplete knowledge of underlying hidden variables. However, Bell's work showed that there are some problems with hidden variable theories.
Re:Since I can't see air it must be another univer (Score:3, Interesting)
First off, IANAP (Physicist). But...
Nothing makes that decision. 'You' evolve every which way in the multiverse, and each copy has the same continuity of consciousness that you do.
>Why is it that you only see one universe, that you only exist in one universe?
You only see one universe because the interference between them only happens on very small scales. You exist in every universe that exists from the moment you were born (assuming that you are still alive in them).
>What decices where you/your conscience goes? Maybe this is the free will? I don't know but this bothers me.
Your consciousness splits just like everything else.
Re:Isn't this just the double-slit experiment? (Score:3, Interesting)
This is an error in the article. There's been a consensus among physicists for a long time (at least 50 years) that the many-worlds interpretation is perfectly valid, but the Copenhagen interpretation is also perfectly valid. Neither interpretation is right or wrong, because neither makes any prediction that contradicts the other. There are actually models of quantum mechanics that are even more wildy different (IIRC a guy named Bell did a lot of research on this ca 1970), although eliminating one type of weirdness just requires introducing some other type of weirdness. The thing is, none of these are different theories, they're just different ways of discussing the same theory.
They found a neat effect with photons, yes.
The do-it-yourself experiment described in the article is a reproduction of an experiment that's 200 years old, and has nothing to do with photons. Photons, quantum mechanics, and the many-worlds interpretation have been understood for 70 years. The article isn't describing current research. It's a garbled, nonsensical paraphrase of someone else's popularization of some cool physics that's been understood since the 1930s.
Re:Actually it was on Star Trek: TNG (Score:5, Interesting)
You seem to know much more about Many Worlds than I do; can you tell me how this theory (or translational) has greater predictive power than the Copenhagen interpretation? It's difficult to create a consistent interpretation of QM that both Occam and Bell would agree on.
Re:Since I can't see air it must be another univer (Score:2, Interesting)
Correction: the physics community hasn't satisfactorily explained gravity AT ALL. Warped space-time does not explain why a shotput feels heavy in our hand. In the October 2003 issue of Discover, Michael Martin Nieto, a theoretical physicist at Los Alamos National Laboratory in New Mexico, was quoted as saying, "We don't know anything. Everything about gravity is mysterious."
OK; here's a force that supposedly emanates from all matter, yet has no identifiable power source, does not decay or diminish over time, and uses no fuel. Whatever happened to Conservation of Energy? The orbit of our planet around our sun is as close to a perpetual motion machine as we have ever seen.
And don't try to snow me with that old Work Function dodge. Physicists would have us believe that gravity never does any work. That it requires no work to keep our planet from zooming off in a straight line into space. That a boulder being forcibly held down on Earth's surface requires no energy. They say that, since w=fd (work = force x distance), no movement means zero distance and therefore no work, therefore no energy required. They modify the work function equation (which was never intended to be a "work detector") to explain that Earth being held in its orbit around the sun requires no energy since the earth is moving perpendicular to the constraining source. The modified Work Equation gives a zero result; therefore no energy is required.
What a load of crap! Go outside whatever building you are in right now and try as hard as you can to push it to the east for 10 minutes. Guess what? According to this logic, you have expended no energy! Oh, never mind that spaghetti feeling in your arms and legs. You've expended no energy because the building never moved.
Please. These guys don't understand/can't explain the most ubiquitous, fundamental force in the entire universe, and use flawed logic to "explain" it, yet expect us to fall at their feet when they come up with these inane theories. It's easy to find a theory that explains only some of the observations.
Re:Actually it was on Star Trek: TNG (Score:5, Interesting)
Instead, what happens is that (using Shroedinger's cat as an example) , the atom in the box is a superposition of a decayed and non-decayed quantum state. The cat, having it's life associated with said waveform become a superposition of live and dead. When you open the box, the photons (exhibiting superimposed quantum states) are read by your eyes and reported to your brain which then also splits into a superposition of states, one seeing a live cat, the other seeing a dead cat. Each quantum state of your mind then basically sees either a live or dead cat. You think that you are seeing either a live or dead cat and then assume that the cat's quantum state must have collapsed into one of those states when you looked at it.
The many worlds theory simply states that this is an illusion, you yourself have been split into multiple states and each state coexists without the knowledge of the other states and interprets the world as if waveforms collapse. Instead, the reality is that every possible quantum event not only does happen but happens simultaneously and in the same place. We just can't 'see' it.
The many worlds theory assumes that the waveforms never collapse which is basically the most faithful interpretation of the underlying equations. Any theory that talks about waveform collapse is basically tacking on extra baggage to try to explain this 'collapse' that the many worlds theory simply does away with.
Personally, I think the many worlds theory is by far the most elegant and likely explanation, all of the other versions look a lot like epicycles to me. OTOH, the many worlds hypothesis is fundamentally impossible to prove or disprove since no experiment can demonstrate that multiple quantum states coexist. (at least to my knowledge) However, lack of provability or predictive power probably says more about inherent limitations on experimental science than the validity of this theory.
Incidentally, if you examine cosmology with the many worlds interpretation, you can start applying thermodynamics laws to the universe since pretyty much every possible set of events is going on simultaneously - including events that would mimic a Big Bang.