RE: Quantum Rebel
As long as the wires interact with the photons, the information is destroyed. I made the nonzero width reality comment to further build up the case. And you are right, a single wire should also do the trick. A better (and far simpler) way to challenge complementarity would be to use a low-intensity interferogram in a photographic film or CCD. At first the photons being detected are few so the shot (particle-like) aspect is more obvious. As more photons are integrated, the classical interference pattern is observed. Can there be a transition region where both aspects are observable? -Original Message- From: Russell Standish [mailto:[EMAIL PROTECTED] Sent: Friday, August 13, 2004 11:29 PM To: Fred Chen Cc: 'Everything List' Subject: Re: Quantum Rebel It has nothing whatsoever to do with finite width of the absorber. Adding an infinitesimally thin wire into the experiment is sufficient to destroy which way information. On Fri, Aug 13, 2004 at 11:24:06PM -0700, Fred Chen wrote: Yes I think this is correct. The theoretical zero amplitude region in the interference plane of the wires is also of zero width, while on the other hand the wires are obviously finite width. The wires do interact with the photons in reality, or equivalently, diffract the waves coming from the slits. So in the end each detector will detect photons coming from both slits. If you covered up one of the slits, but left the wires in place, both detectors will detect photons originating from the slit. So complementarity (if defined as exclusive particle/wave observation) has not been disproven. The particle-tracking information from each slit is destroyed by interaction with the wires. Fred -- *PS: A number of people ask me about the attachment to my email, which is of type application/pgp-signature. Don't worry, it is not a virus. It is an electronic signature, that may be used to verify this email came from me if you have PGP or GPG installed. Otherwise, you may safely ignore this attachment. A/Prof Russell Standish Director High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile) UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 () Australia[EMAIL PROTECTED] Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks International prefix +612, Interstate prefix 02
RE: Quantum Rebel
Russell, I agree with what you state below. But consider the following experiment. Instead of two beams of equal intensity interfering, as in classical inteferometry, one has unequal amplitude beams. Specifically, Beam A: 0.9*exp(iax+ibz-iwt) Beam B: 0.1*exp(-iax+ibz-iwt) The interference pattern is of the form: Interference field = [cos(ax)+i*0.8sin(ax)]exp(ibx-iwt) So the resulting photon distribution follows the intensity, or the field amplitude squared: Interference intensity = 0.64+ 0.36*cos^2(ax) This wave pattern will begin to appear after sufficient number of photons, but each photon is always ~99% (81/82) likely to have originated from Beam A, based on conservation. If Beam A and Beam B had different amplitudes, you would maximize the uncertainty of the photon origin since you have to say 50/50 likelihood for a photon coming from either A or B. The complementarity principle's strongest statement is 100% certainty, and that cannot be attained. But we can still get an idea of the wave interference pattern and 'which way' information with high (but not 100%) certainty in gray-transition cases such as above. Fred -Original Message- From: Russell Standish [mailto:[EMAIL PROTECTED] Sent: Saturday, August 14, 2004 2:51 AM To: Fred Chen Cc: 'Everything List' Subject: Re: Quantum Rebel On Fri, Aug 13, 2004 at 11:43:10PM -0700, Fred Chen wrote: ... A better (and far simpler) way to challenge complementarity would be to use a low-intensity interferogram in a photographic film or CCD. At first the photons being detected are few so the shot (particle-like) aspect is more obvious. As more photons are integrated, the classical interference pattern is observed. Can there be a transition region where both aspects are observable? This does not challenge complementarity. Consider a double slit apparatus with the photon source's intensity down so low that each individual photon can be observed hitting the screen one at a time. But when one plots the distribution of positions where the photons strike the screen after observing many of them, the interference pattern results. This is simple and uncomplicated, but is not what the complementarity principle is about. Now consider that you have information about which slit the photon passed through before hitting the screen - ie each photon is labelled 1, 2, 1, 1, etc, according to whuch slit it passed through. Therefore, you can separate the observed photons into two sets, according to which slit the phtons passed through. The distribution of each subset corresponds to a single slit experiment, and the final distribution must be the sum of the two single slit experiements. But single slit experiments do not have interference patterns - hence the sum cannot have an interference pattern either. Consequently, if you have any way of knowing which slit the photon went through (the which way information), then you cannot have an interference pattern. This is what the complementarity principle means. Cheers -- *PS: A number of people ask me about the attachment to my email, which is of type application/pgp-signature. Don't worry, it is not a virus. It is an electronic signature, that may be used to verify this email came from me if you have PGP or GPG installed. Otherwise, you may safely ignore this attachment. A/Prof Russell Standish Director High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile) UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 () Australia[EMAIL PROTECTED] Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks International prefix +612, Interstate prefix 02
Re: Gravity Carrier - could gravity be push with shadows not pull?
Eric, It may not explain gravity but your phenomenon seems strikingly similar (with its repulsive push picture) to the concept of cosmological constant or quintessence, which has a great deal (it is believed) to do with the expanding universe and its fate. See http://physicsweb.org/article/world/13/11/8 as one salbeit somewhat dated starting point. The anthropic principle and related multiverse discussions can consider this as one parameter that distinguishes different universes, especially since it can modulate the ability to support life. Fred - Original Message - From: Eric Hawthorne [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, February 26, 2004 1:46 AM Subject: Re: Gravity Carrier - could gravity be push with shadows not pull? Caveat: This post will likely demonstrate my complete lack of advanced physics education. But here goes anyway. Is it possible to model gravity as space being filled with an all-directional flux of inverse gravitons? These would be particles which: 1. Zoom around EVERYWHERE with a uniform distribution of velocities (up to C in any direction). 2. Interact weakly with matter, imparting a small momentum to matter (in the direction that the iGraviton was moving) should they collide with a matter particle. The momentum comes at the cost that the iGraviton which collided with mass either disappears or at least reduces its velocity relative to the mass's velocity. So note that: 1. If there was just a single mass, it would not receive any net momentum by collisions from iGravitons because iGravitons with an even distribution of velocities impact it from all sides with equal probability, no matter what the mass's velocity. (This is true because C is the same for each mass no matter how it's travelling, so even distribution of velocities up to C is also the same from the perspective of each mass regardless of its velocity. 2. If two masses are near each other, they shadow each other from the flux of iGravitons which would otherwise be impacting them from the direction in between them. This shadowing would be proportional to the inverse square of the distances between the masses, and would be proportional to the probability of each mass colliding with (i.e. absorbing) iGravitons, and this probability would be proportional to the amount of each mass. (So the iGraviton shadow between the masses would have properties like a gravitational field). 3. The mutual shadowing from momentum-imparting flux from all directions means that net momentum would be imparted on the masses toward each other (by nothing other than the usual collisions with iGravitons from all other directions.) 4. The deficit of iGravitons (or deficit in velocity of them) in between absorbtive masses could be viewed as inward curvature of space-time in that region. Amount or velocity distribution of iGraviton flux in a region could correspond in some way with the dimensionality of space in that region. I find this theory appealing because 1. it's fundamental assumption for causation of gravity is simple (a uniformly-distributed-in-velocity-and-density flux of space-involved (i.e. space-defining) particles.) 2. The paucity of iGravitons (or high iGraviton velocities) in a region corresponding to inward-curving space is an appealingly direct analogy. You can visualize iGravitons as puffing up space and a lack of them causing space there to sag in on itself. I'd be willing to bet that someone has thought of this long before and that it's been proven that the math doesn't work out for it. Has anyone heard of anything like this? Is it proven silly already? Cheers, Eric
Re: Black Holes and Gravity Carrier
Nice link, great topic. This does beg the question, is there an event horizon for gravitons, and presumably the answer for that would be the singularity. Here is something to ponder: do virtual gravitons generate more virtual gravitons? Consider a planet in circular orbit around its star. Consider the gravitational force of this system on an external body far away, e.g., a comet. The force on the comet would be due to the mass of the planet, plus the mass of the star, plus the gravitational energy of the star-planet system. So the gravitational field, an exchange of virtual gravitons, would be the source of new virtual gravitons to be exchanged with the comet, or in fact anything outside this system. This could extrapolate ad infinitum, as we take into account each virtual exchange of gravitons generating another virtual exchange of gravitons. Fred - Original Message - From: Hal Finney [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, February 16, 2004 4:30 PM Subject: Re: Black Holes and Gravity Carrier Ron McFarland writes: If a gravity carrier has any mass whatsoever then by what mechanism could it possibly and in such abundance escape from a black hole event horizon and make itself known in our observable universe? This is not really a multiverse question, but rather a common query relating to relativity and QM. See question 6 in part 2 of the sci.physics FAQ, How does the gravity get out of the black hole?, at: http://www.faqs.org/faqs/physics-faq/part2/ The short answer is that when you model forces as the exchange of particles, it is actually done as the exchange of virtual particles; and virtual particles can go faster than light, hence can escape from black holes. Hal Finney
Re: Is the Multiverse twice as large?
Mirror matter is very interesting. It's an example where unbreaking a symmetry (in this case 2-fold) results in an effectively parallel universe. It makes me wonder if unbreaking an infinite-fold symmetry would similarly generate a multiverse family, and what would this symmetry be? - Original Message - From: Saibal Mitra [EMAIL PROTECTED] To: Everything [EMAIL PROTECTED] Sent: Wednesday, January 15, 2003 3:57 AM Subject: Is the Multiverse twice as large? Well, just perform this simple experiment to find out. See: http://arxiv.org/abs/astro-ph/0301229
Re: My history or Peters??
-Original Message- From: Fred Chen [mailto:[EMAIL PROTECTED]] A codified description of how the all-universes model works would be nice. Will a program that executes all programs really suffice? It seems more like an analogy than an actual model. With a computational model of bacterial growth, for example, one can simulate this on a computer screen as multiplying dots, or possibly even provide a realistic visual image of a growing bacterial population, but is that the same as an actual petri dish? Did someone suggest it was? I believe computation is a good way to represent whatever we want to describe. The all-universe, or multiverse, model seems like a suitable thing to pursue computationally. However, making the jump from the description or representation (which will be computation-driven) to the actual phenomenon or experience, still needs to be dealt with. When you mentioned a complete description of reality vs. a complete codified description of how it works (you also acknowledge these to be different), this was the immediate response in my mind. So I think we agree? - Original Message - From: Charles Goodwin [EMAIL PROTECTED] To: [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Sent: Wednesday, September 05, 2001 2:15 PM Subject: RE: My history or Peters?? I was talking about the laws of physics. It's possible in principle for those to be known (I think). One can also know all there is to know while knowing that one's knowledge is incomplete! Obviously a complete description of reality is impossible (where would you store the information about the state of every particle?) but a complete codified description of how reality works is another story. Charles I had written: The 'laws of physics' is now a really outdated term, I think. The scope is not so clear these days (where does physics end, and another field begin?). One can even consider the all-universe model to be almost a 'law' of physics, in the sense that it is often invoked to explain certain problems in physics. The term 'laws of physics' is shorthand for whatever rules the universe operates by on the most fundamental scale. What you call it or what field you consider yourself to be in isn't really relevant. For example the currently understood 'laws of physics' include the four forces, the nature of matter and the nature of space-time. The sort of thing we're discussing here can often be conveniently abbreviated as 'the laws of physics'. I'm not sure what point you're trying to make by arguing about semantics? Charles There is something about complete knowledge that bothers me. You had mentioned the laws of physics can possibly be completely understood. In my response, I was saying, depending on what 'the laws of physics' means, that could be true or impossible. That's where the scope is important. If the laws of physics only needs to cover the current state of particle physics without grand unification, it is true. On the other hand, a complete physical or mathematical description of our thoughts is impossible, for Godelian reasons. Fred
Fw: James Higgo
- Original Message - From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, August 20, 2001 12:47 AM Subject: Re: James Higgo Dear Fred, Thank you for your concer. Perhaps you could forward this notice to the rest of the people on the list (I don't have access). Many thanks, Jenny Higgo (James'mother at [EMAIL PROTECTED]). A service of thanksgiving for the life of James Anthony Higgo will be held in Haileybury College Chapel, Hertford, on Tuesday 19th September at 4.00 pm. Refreshments afterwards. This universe will be a duller place without him. I was shocked to hear of James Higgo's passing. I still have his replies to some of my postings. The multiverse concept is of little comfort on occasions like these. Fred
Re: James Higgo
I was shocked to hear of James Higgo's passing. I still havehis replies to some of my postings. The multiverse concept is of little comfort on occasions like these. Fred
Re: Introduction (Digital Physics)
I don't see why we should limit ourselves to the simplest possible universe containing consciousness. I would think that all worlds containing consciousness would be inhabited naturally. Joel Actually I agree, fundamentally. Perhaps, there is just a gut feeling around that simplest possible goes hand-in-hand with more instances, and hence, a greater likelihood that that description is accurate for our world. In physics and cosmology, and even in many engineering siutations, we have always tried to avoid fine-tuning, which is associated with greater complexity. The best models have the least need for fine-tuning. So that is where I am coming from. The all-universes (and related) approaches have appeal precisely for this reason. Fred
Re: Introduction (Digital Physics)
Joel, thanks for your clarification. Fred: If two worlds within this everything are contradictory or not consistent with each other, with no common ground, how exactly do they interact? Well I believe the universe is strictly local and completely homogeneous at the bottommost layer. So even though two worlds/cosmoses may be very far apart, eventually the information from one will reach the other. There they will interact, although the result may be completely unexpected from anything that was happening in the two worlds when they were apart, and their inhabitants may be long since gone. Perhaps you are saying all worlds have some commonality eventually? Such as the program you mention below? I imagine all possible programs for all possible universes. If there were a single program running the whole show, I would ask, why that program? Because that one program runs all the others. All the others are embodied by the larger computation. Any program that instantiates all programs should be as good as any other, don't you think? All of these superprograms souuld be equivalent, since they all do exactly the same thing. Yes? As I mentioned in my reply to scerir, we can't avoid self-referential problems, however, if we try to represent or describe ourselves. But if we are merely three-dimensional bit sequences - 3D movies, then all we have to do is find a program that generates our movie. But instead of looking for our particular movie, it's easier to find the program that generates all movies... which must necessarily also generate ours. I don't see any problem with that description. It's all bits. Joel Sounds like you are going after some magic program that generates all possible programs. Would this program be a logical necessity in and of itself? That is, must it necessarily exist? Or would it just happen to exist? Fred
Re: Introduction (Digital Physics)
Joel, let's clarify our positions: To be clear, I envision just one universe that contains everything. Within it may be many worlds or sub-worlds, but these are not independent. They interact. If two worlds within this everything are contradictory or not consistent with each other, with no common ground, how exactly do they interact? I feel two such worlds must be independent entities within the set. This is different from the case of universes which may be linked by wormholes or MWI splittings or whatever. Furthermore, I imagine there is a single program that runs the whole universe, and that we can know that program exactly. I'm not sure what Godel is doing here. I imagine all possible programs for all possible universes. If there were a single program running the whole show, I would ask, why that program? As I mentioned in my reply to scerir, we can't avoid self-referential problems, however, if we try to represent or describe ourselves. Adopting that perspective, we should be able to justify that a simulation of our universe does not appear overly fine-tuned. At least that would suit my aesthetic tastes. As in fine-tuned to support life, etc.? No, I don't see any necessity in that either. Where there is life, there is life. That's enough for me! Joel True, there is no necessity in avoiding fine-tuning. It just makes the model more compelling in my opinion. Fred
Re: Introduction (Digital Physics)
Hello again Joel. I think I can agree with you, in a pragmatic sense, with what you state below. I agree that any useful TOE should be able to be implemented on a (large enough) computer. This computation can then SIMULATE the relevant or important aspects of the universe we observe, or all aspects of other possible universes, with their APPARENT real-number continua and infinite sets. Godel's theorem prevents us from simulating all aspects of our universe. Adopting that perspective, we should be able to justify that a simulation of our universe does not appear overly fine-tuned. At least that would suit my aesthetic tastes. Fred I'm simply trying to get people to confront the truth that we humans are incapable of devising Theories of Everything that are NOT run on a universal computer. That's all. Many will say, Of course! We know that!. And then they go on, as if nothing happened, talking about the probabilities of items in infinite sets, and independent tosses of a fair coin, and quantum indeterminacy, and the continuum of the real numbers, as if these things exist! If we cannot program it... it's not a Theory of EVERYTHING. It's just a description. Let us take the realist approach and focus on the things we can actually compute fully. Joel
Re: Natural selection (spinoff from History-less observer moments)
[EMAIL PROTECTED] wrote: In a message dated 05/18/2000 1:41:52 AM Pacific Daylight Time, [EMAIL PROTECTED] writes: Actually, James, I read something wild into your sentence, interpreting competition as the selection mechanism. That does strike me as more promising than Occam's razor. I am interested in pursuing this line of thought as a means of selecting not only ideas perceived to be correct, but also universes. Anthropic compatibility has traditionally been the criterion to select observed universes. It does not appear feasible to apply this analogously to ideas, though. But perhaps white rabbits are naturally disfavored in this scheme? Higgo James wrote: It seems to me that a good way of selecting one idea over is [sic] competition is Occam's razor Great Fred, I had exactly the same thought. The selection of ideas, just like the selection of life forms, does not have to follow Occam. Otherwise we would still be slime in the mud. Anthropic selection is yet another kind of selection. While natural selection (selection of the individual by the world) is 3rd person effect, anthropy (selection of the world by the individual) is a 1st person effect. They are identical except that the frame of reference is different. Interestingly, these processes seem to be acausal: the fittest survives because it does. We see the world we see because we are alive to see it. You raise an important issue. In the competition, there has to be some criteria for survivability. Self-consistency (essentially the anthropic principle being applied to whatever is being selected) could be one. Logical consistency (which forbids p and not p being true) could be another. Higgo James wrote: This is Dawkins' memes theory Great, if at least 3 people independently had the same thinking, it can't be totally devoid of merit. Higgo James also wrote: The answer is simply the anthropic principle - which should strictly be applied to thoughts, not to people. The question, 'why is it that I am having this exact thought?' exists. You should not be surprised that your thought is that question. There is something circular about this, but a thought that exists in a 'hard' (perceived) sense should be self-consistent, which I think is what you are saying. (My earlier statement about AP being applied to ideas was meant to say not every thought of ours is necessary to our survival.) Fred
Natural selection (spinoff from History-less observer moments)
Actually, James, I read something wild into your sentence, interpreting competition as the selection mechanism. That does strike me as more promising than Occam's razor. I am interested in pursuing this line of thought as a means of selecting not only ideas perceived to be correct, but also universes. Anthropic compatibility has traditionally been the criterion to select observed universes. It does not appear feasible to apply this analogously to ideas, though. But perhaps white rabbits are naturally disfavored in this scheme? Higgo James wrote: It seems to me that a good way of selecting one idea over is [sic] competition is Occam's razor
Re: The Game of Life
How would you verify your Life pattern has achieved SAS status? Ask it. This is indeed a creative solution. You are presuming, though, that the SAS's in your Life world will understand you. The only way you can know this is if you had encoded their language/communication channel beforehand in a Turing fashion. You would also have to anticipate the answer(s) they would give you. If they do not understand you or simply ignore you, the asking test fails. Fred
Re: The Game of Life
How would you verify your Life pattern has achieved SAS status? Jerry Clark wrote: More relevantly, it is posulated as highly likely that, starting with a random Life formation, SAS's will evolve of their own accord. One proves this by showing that our UTM is also a universal constructor (can take a coded blueprint and build out of it a machine at least as complex as itself). UTM is also a universal destructor and therefore mobile. Eventually you get evolution and SAS's. This is SAS's for free and a much more interesting result than the fact that one can build a UTM in the life universe that simulates e.g. this universe. Such 'Life' evolution raises an interesting question: These SAS's would build universities and study mathematics, computer science and physics. Some J.H.Conway of the Life universe would discover the amusing and diverting Life game, and start discovering gliders, glider guns, space rakes etc. Sooner or later a physicists would hear about this new development and the realisation would be made that their universe *is* a Life simulation. Such a discovery would of course revolutionise the study of physics for these SAS's. More interestingly still: when are *we* going to discover some CA or similar which turns out to be *our* universe? In my lifetime I hope. Fred Chen wrote: [EMAIL PROTECTED] wrote: Fred Chen, [EMAIL PROTECTED], writes: When this game is run, complex patterns can emerge from simpler ones in a dynamic fashion. So, my question is, can this game generate SAS's? It has been found that Life is Universal, meaning that you can construct a Universal Turing Machine out of the Life rules. It would then be possible to program it to simulate any mathematical or logical system, hence SAS's should be possible. Hal You are right. You can construct a UTM based on Life rules. Fred
Re: How does this probability thing work in MWI?
I think there is an additional complication if you factor in the possibility of duplicate universes, i.e., more than one instance of exactly the same universe, with its unique history, observers, etc. This can provide a potential path for weighting the probabilities, but only if you link the 'normality' or 'simplicity' of a possibility to the number of instances that are realized. Why should it be the case that each bitstring representation gets one universe? To me, the most natural scenario is that each universe has an infinite number of instances (exact copies or duplicates of same bitstring representation), so the probability distribution in this case is undefined and you cannot define any probabilities. Since we do not feel this to be the case (if we're discussing likelihood of, e.g., white rabbit universes), we possibly have a very unnatural situation where some contingent universal non-uniform mathematical distribution f is governing the number of instances of each universe, across the entire universe ensemble. One benefit of this case is the probability distribution f may even be used to rule out the existence of certain very contrived, complex universes (f-0). The question then becomes, what is this distribution f? Fred Fritz Griffith wrote: I have read the Everett FAQ (http://soong.club.cc.cmu.edu/~pooh/lore/manyworlds.html), and I think it's one of the most comprehensive descriptions of MWI I have found on the internet. I have one question though - in question 24: Does many-worlds allow free-will?, it says, If both sides of a choice are selected in different worlds why bother to spend time weighing the evidence before selecting? The answer is that whilst all decisions are realised, some are realised more often than others - or to put to more precisely each branch of a decision has its own weighting or measure which enforces the usual laws of quantum statistics.. My question is, where does this weighting come from? Do some branches occur more often than others? Or is there just some sort of assumed probability as to which world will be yours? Fritz Griffith __ Get Your Private, Free Email at http://www.hotmail.com
Re: unsubscribe flipsu5@earthlink.net
Please retain me on the distribution list. The dialogs are beginning to become interesting. Thanks, Fred [EMAIL PROTECTED] wrote: 32720 [EMAIL PROTECTED] [EMAIL PROTECTED] You have been removed from the list. If this wasn't your intention or you are having problems getting yourself unsubscribed, reply to this mail now (quoting it entirely (for diagnostic purposes), and of course adding any comments you see fit). Transcript of unsubscription request follows: -- From [EMAIL PROTECTED] From: [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: unsubscribe [EMAIL PROTECTED]
