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Post by mrsonde on Apr 29, 2013 16:41:55 GMT 1
I've been reading about Wheeler's attempts before he died to convert quantum mechanics - all physics, and reality itself, actually - into the language or rather formalism of information theory. If it's possible, and I sense intuitively it must be right, then this changes pretty much everything we've learned is established in known physics - the silly mess about entropy, order, the heat death of the universe, all that obvious miscomprehension, for example. But for the moment an interesting possibility occurs - because information, although expressed in bits, and although bits must be embodied in physical form, is nevertheless free of the laws of thermodynamics. It is not the same thing as energy - conservation and entropy don't have the same iron grip (because nothing can itself be a bit of information - if I don't turn up, it means I'm dead - and even the 1 contrast to 0 can itself mean an infinity of other information, in an infinite range of complexity, and hence energy and order content.) And it seems to me it also escapes Einstein's speed of light barrier. Imagine, for example, that we have discovered another habitable planet - one like Marchesa posted about last week: It's inhabited by an alien civilisation - or we ourselves colonise it. Say that like this one it's a thousand light years away. According to SR any communication between Earth and it will take at least a thousand years, therefore - for a round trip, so that information can be exchanged, responded to: two thousand years. But suppose we set up a communication system between it and us using the EPR Paradox, and entangled particles. This could be a constant stream, of course - a constant beam of emitted hydorgen photon pairs, for example. One photon we send round and round here, the other we emit to our discovered distant planet. We have an agreed common language by which we can interpret any encoding we put into our photon stream (it could of course be photos, or video, just as easily as text, for that matter.) Now, in order to send our message, have it received instantaneously, and receive an instantaneous reply, ad infinitum, all we need to do is take our thousand-year old travelling photon beam and determine one of its properties - its spin, say - by switching a filter through which it passes into one of two known states. Being entangled, we know that its thousand-year old partner is now in a complementary state, and will be received as such by our distant communicators. Our message has been sent instantaneously. What's wrong with this picture?
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Post by fascinating on Apr 29, 2013 16:58:38 GMT 1
I don't think anything is wrong with the picture, but there again that might be because I don't fully understand it. Are you saying that your scheme will in fact halve the communication time from 2000 years to 1000 years? First you have to create a huge number of entangled photons, then send them to the distant planet, which will take 1000 years. Then any change in the state of those particles on the planet made by the colonists will be recorded instantly in the pairs that you have carefully kept in a box here on Earth for at least 1000 years. Presumably if you had another box (pair of boxes) of entangled protons, you could reserve those ones for communicating the other way.
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Post by mrsonde on Apr 29, 2013 17:17:10 GMT 1
I don't think anything is wrong with the picture, but there again that might be because I don't fully understand it. Are you saying that your scheme will in fact halve the communication time from 2000 years to 1000 years? No, no - I'm saying that the communication time would be instantaneous. Well, virtually - the time expired would merely be the time required to translate the message in the stream ( streams, rather - our sister planet is also sending us a thousand-year old beam, of course.) Yeah - you shine light at the suitable frequency onto a vat of hydrogen. Go on forever, as long as you keep the hydrogen replenished. Yes - but the message won't. That we're generating by measuring the state of one of the entangled photon pairs - the one here, in front of us, now. Its entangled partner was sent off to our sister planet a thousand years ago, when they were both emitted - we've just kept ours hanging around, ready when needed to be so encoded. C'est ca. Well - it's a constant stream, both ways. You could therefore hold a conversation as instant as talking to someone in the same room. This has profound implications not just for SR - but for GR (the nature and shape of the space-time continuum) and what space and time mean. It's a revival in effect of the instantaneous NOW: which in turn turns upside down what we've come to habitually think of as the Big Bang, the expanding universe - the nature of reality itself. It's - Berkeleyian. Information, meaning - Mind - becomes primary.
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Post by fascinating on Apr 29, 2013 17:29:54 GMT 1
Hmmm, well all that is VERY deep isn't it? I don't think I am qualified to give an opinion. It still remains the case that we have to wait 1000 years for the entangled photons to get to the distant planet, though I appreciate that, once they have arrived, there can, in theory, be instant communication.
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Post by mrsonde on Apr 29, 2013 17:36:39 GMT 1
I don't think I am qualified to give an opinion. It still remains the case that we have to wait 1000 years for the entangled photons to get to the distant planet, though I appreciate that, once they have arrived, there can, in theory, be instant communication. Yes - I clearly haven't explainedmyself adequately. The photons - the energy - have to take a thousand years between the planets. The information - the meaning - they can convey does not. We are of course talking about God. No - seriously. Think about it. I shall too - I'm off to the beach now, to get my firewood. Laters.
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Post by fascinating on Apr 29, 2013 17:46:50 GMT 1
From the time of creating the entangled particles, to the time when you convey the information, is going to take 1000 years is it not?
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Post by mrsonde on Apr 30, 2013 20:09:17 GMT 1
From the time of creating the entangled particles, to the time when you convey the information, is going to take 1000 years is it not? Yes. A bit like, say, coal - took a very long time to make, a very long time ago, but you can dig it up and burn it today. The more interesting point is that, from a conventional standpoint - the sort of conventional view about light and time and communication that we've all grown up with, we've all been taught a thousand times as the physically correct way of thinking about the universe - we're able to hold a conversation by this means with someone from a thousand years ago. Which just goes to show that view of Reality must be wrong, and has always been wrong. Or there's something seriously wrong with my thought experiment - but I don't think there is. Technically, perhaps - but the precise technical details of the equipment are superfluous. From a physics point of view it doesn't matter what you use - photons, electrons, cosmic rays. The other possibility is there's something wrong with the whole entangled particles theory. But experiments would seem to rule that out, very firmly. So - what's wrong is the view that c delimits and shapes inversely the universe. The Minkowski space-time "funnel" is not the unbreachable boundary at all, and it is not an idle metaphysical classical mistake to think of what's beyond it as real, and capable of influencing the merely visible universe. In fact, it must do so - every particle in the universe is so entangled. This throws into complete question all the calculations that have led to the "dark matter" and "dark energy" theory, incidentally - all the estimations of how much mass the universe contains.
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Post by fascinating on May 3, 2013 11:26:57 GMT 1
Would you run that past me again? By "conventional" do you meant the theory of relativity that states that nothing can travel faster than the speed of light? I assume physicists must be aware of the caveat about entangled particles changing instantly together, no matter what distance they are apart. There's also the fact that the Universe did, in the past, inflate so fast that galaxies were pushed apart faster than the speed of light. It doesn't seem necessary to change the whole view of the Universe because of that.
Maybe you ought to find a website where you can ask these hard questions of physicists. Or maybe phone Dr Karl on Radio 5 on early Thursday morning. I would be glad to learn what response you get.
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Post by mrsonde on May 6, 2013 5:41:15 GMT 1
Would you run that past me again? Pleased to. Well, yes - and all its implications, which are of course rather more far-reaching. Errr...there's no caveat. It's an implication of quantum mechanics, not relativity theory, and until very recently there's been no crossover connection between the two. Except of course as a thought experiment - first dreamt up by Einstein, Rosen and Podolsky as a deliberate paradox to show that quantum mechanics must be incomplete (because it has this implication of what Einstein termed "spooky action at a distance"). Recently actual experiments in the laboratory have demonstrated that the EPR paradox actually occurs, however: furthermore, they've gone a lot further. Google the quantum eraser experiment, for example, if you're really up to having your mind boggled. These experiments have not really percolated down to even the general scientific community, let alone the broader intellectual public. The implications are so staggering that most people - physicists included - simply don't think about them. Where do you start? As Feynman famously said, many times, in many ways, if anyone (including himself) thinks they understand quantum mechanics, they don't. In terms of this specific thought experiment, I haven;'t come across it before - and I doubt that its implications have been thought about, or discussed extensively in the scientific literature if they have at any rate. They literally are...unimaginable, from all conventional standpoints - the conventional view of quantum mechanics included. It's a very, very tenuous theory - not a fact. And that's definitely not a fact either! It's not even the theory, sorry. The theory is that c is determined by the rate of that expansion. That is, they're the same thing. Whatever the rate is, that's what c is. And you'd never be able top compare the two, of course. Huh? I'm afraid if simultaneity is universal - if there is a simultaneous NOW throughout the entire cosmos, as Newton and everyone else before Einstein envisaged time - then the generally upheld view about the metaphysical implications of relativity theory are out of the window. By metaphysical I don;t mean anything non-scientific, or even non-positivist - merely the overall meanings of our most basic concepts in science. Concepts like space, time, energy, the universe. I've spent the past 35 years doing my best to keep up with what physicists think. I can predict exactly what any of them that could give a relevant answer would say, if you're interested. In the face of this thought experiment, they wouldn't say anything. Except - ummmm...well, that's a very interesting problem...there must be an error of composition in it somewhere...but I'd need to think about it further... ;D Are you taking the piss? I thought for a minute you were being serious.
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Post by mrsonde on May 6, 2013 15:53:16 GMT 1
To illustrate what I mean by saying a complete reassessment of the metaphysics of Relativity is required by this implication, consider the thoroughly discussed circumstance of the Twins or Clocks Paradox, where time and space undergo Lorentz contractions due to relative motion. To keep things simple suppose that this sister planet of ours is moving towards or away from us rectilinearly with an appreciable velocity, and it's appreciable enough to be able to easily neglect any dilation effects due to the accelerations and curvilinear motions of our respective orbits. If that's too hypothetical, we could easily arrange the experiment so that we both send rockets towards or away from each other, and exactly balance out our respective accelerations, so that we can merely concentrate on the effects of uniform relative velocity.
Now, according to SR we will observe in this situation that the clocks of our sister planet are running more slowly than ours - whatever clocks we choose to measure the passage of time, caesium vibrations, circuit paths of light, anything, we see their clocks ticking by at a slower rate - a rate we can predict precisely according to the transformation equations of SR. Exactly the converse observations occur from the viewpoint of our sister planet, of course - our clocks are running more slowly than theirs, according to their measurements.
It is a fundamental assertion of Relativity Theory that this mirrored observation is not a matter of appearance, or illusion, but a necessary consequence of the basic structure of space-time and the invariant speed of light. We are moving relatively to each other and therefore it is literally true that our clocks must be ticking by at different rates; it is merely a question of which reference frame we rather arbitraily choose to take our observations from. It is literally true that we are both entitled to say we are at rest, from our frame of reference, and only the other is moving towards us; it is literally true, therefore, that from the (illegitimate, metaphysically speaking) God's Eye reference frame, both of our clocks are both running more slowly than the other's. We have different space-time trajectories to each other, and as there is no such thing as simultaneity, a universal real rate of time passing, the appearances that we observe are literally all that there is.
Now, this seeming paradox is settled in SR by dint of the mathematical calculations used to show that the paradox arises from the appearances of the situation - the paradox arises because we are both having to take account of the alterations in the space-time metric caused by the relative motion of the other.
But under this thought experiment of a communcation medium possible through entangled particle exchange, that sleight of hand is no longer available. We can talk instantly to each other. We can give a running instantaneous commentary of what our clocks are registering - we both know, instant to instant, exactly at what rate our respective time is passing. We can coordinate our clocks as though they were next to each other - the very fact that conventionally prevents (makes it illegitimate, metaphysically) our moving beyond the appearances in SR: the insuperable stumbling block in a universe where light is the unsurpassable speed barrier of any information exchange.
Obviously, under these circumstances it is logically impossible - nonsensical - for both our clocks to be running slowly in comparison to each other. Nor is it comprehensible in this circumstance that, contrary to the mathematics of the theory, it might turn out that one of the clocks is running more slowly than the other - or if it is, we will have to throw up our hands and admit that we have no possible idea in any of our physical theories to account for which one it would be, or why. The only plausible alternative is the obvious one - it turns out that the clocks are running at the same rate. The observations we make by exhange of light signals (i.e. the conventional manner of communication, rather than the entangled particles means of this thought experiment) turn out to be a matter of appearance only, simply caused by the speed of light barrier. The reality behind it is, on the contrary, one of simultaneity - a uniform, universal, identical rate of time passing, for all observers, whatever their relative motion. Obviously, the same goes for the space metric.
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Post by abacus9900 on Dec 9, 2013 16:54:55 GMT 1
I've been reading about Wheeler's attempts before he died to convert quantum mechanics - all physics, and reality itself, actually - into the language or rather formalism of information theory. If it's possible, and I sense intuitively it must be right, then this changes pretty much everything we've learned is established in known physics - the silly mess about entropy, order, the heat death of the universe, all that obvious miscomprehension, for example. But for the moment an interesting possibility occurs - because information, although expressed in bits, and although bits must be embodied in physical form, is nevertheless free of the laws of thermodynamics. It is not the same thing as energy - conservation and entropy don't have the same iron grip (because nothing can itself be a bit of information - if I don't turn up, it means I'm dead - and even the 1 contrast to 0 can itself mean an infinity of other information, in an infinite range of complexity, and hence energy and order content.) And it seems to me it also escapes Einstein's speed of light barrier. Imagine, for example, that we have discovered another habitable planet - one like Marchesa posted about last week: It's inhabited by an alien civilisation - or we ourselves colonise it. Say that like this one it's a thousand light years away. According to SR any communication between Earth and it will take at least a thousand years, therefore - for a round trip, so that information can be exchanged, responded to: two thousand years. But suppose we set up a communication system between it and us using the EPR Paradox, and entangled particles. This could be a constant stream, of course - a constant beam of emitted hydorgen photon pairs, for example. One photon we send round and round here, the other we emit to our discovered distant planet. We have an agreed common language by which we can interpret any encoding we put into our photon stream (it could of course be photos, or video, just as easily as text, for that matter.) Now, in order to send our message, have it received instantaneously, and receive an instantaneous reply, ad infinitum, all we need to do is take our thousand-year old travelling photon beam and determine one of its properties - its spin, say - by switching a filter through which it passes into one of two known states. Being entangled, we know that its thousand-year old partner is now in a complementary state, and will be received as such by our distant communicators. Our message has been sent instantaneously. What's wrong with this picture? The big problem with this idea (as far as I know) is that when particle A is measured at one location, although particle B will take on a complimentary state instantaneously, regardless of the distance between them, you can never actually predict before a measurement is made what state particle A will be in after it is measured. This means, of course, that it is impossible to send prepared signals because it is all about the probabilities of this or that occurring after measuring particle A, you can never be sure.
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Post by principled on Dec 10, 2013 19:26:13 GMT 1
Abacus Although I'm no expert, this is my interpretation as well. However, I'd like to explore the idea of the instantaneousness of entanglement. As a thought experiment, let's take Mr S' two planets and join them with a massless, solid rod. Moving it .0001mm (or any minuscule movement for the purposes of this thought process) to the left is a 0 and the same to the right is a 1. Because the rod is massless the movement will be transmitted instantaneously, would it not? The speed of information transfer would therefore exceed "C". Returning to entanglement, could such "particle pairs" be connected by some mechanism - as yet unknown but analogous to the rod- where information can be transferred instantaneously yet not breach the law that information transfer can never be faster that the speed of light? P
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Post by abacus9900 on Dec 11, 2013 21:29:33 GMT 1
Abacus Although I'm no expert, this is my interpretation as well. However, I'd like to explore the idea of the instantaneousness of entanglement. As a thought experiment, let's take Mr S' two planets and join them with a massless, solid rod. Moving it .0001mm (or any minuscule movement for the purposes of this thought process) to the left is a 0 and the same to the right is a 1. Because the rod is massless the movement will be transmitted instantaneously, would it not? The speed of information transfer would therefore exceed "C". Returning to entanglement, could such "particle pairs" be connected by some mechanism - as yet unknown but analogous to the rod- where information can be transferred instantaneously yet not breach the law that information transfer can never be faster that the speed of light? P I understand that massless particles move at the speed of light, not instantaneously. I got this from a discussion about the Higgs Boson and somebody was saying that if the Higgs Boson did not exist (or, more specifically, the Higgs field) nothing would have mass and particles would be able to move at the speed of light. Of course we, or anything else that possess mass at present, would not exist and I guess everything would be particles, but I'm no expert. But I'm not aware that there is any way round the problem of the unpredictability of what state a particle will be in when measured because this seems a fundamental aspect of the way quantum objects behave. It's all tied up with the measurement problem where when you attempt to "look" at a quantum object you can only measure its momentum or it's position, not both. This means you are never able to completely tie things down, having to rely on probabilities, not certainties.
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Post by alancalverd on Dec 12, 2013 9:04:35 GMT 1
No. The speed of transmission would be the speed of a compression wave (i.e. the speed of sound) in the rod. If you moved the rod by applying a force to its centre, both ends would move simultaneously, but some time after the initiating event, and since neither would know what had happened at the other end of the rod, no information would have been transmitted from one end to the other.
However, regardless of the speed of transmission, you could claim that the planets were now entangled, since any information generated at the centre of the rod would induce simultaneous equal and opposite states at the ends.
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Post by mrsonde on Dec 27, 2013 7:15:26 GMT 1
Apologies - these responses somehow escaped my notice.
In this experimental set-up you don't need to know what state particle A will be in - you don't even need to know what state its partner will be in. You merely put a polariser in its path. It's allowed through, or it isn't - this gives you potential knowledge of its chirality, and thus collapses the wavefunction of its partner into its complement instantaneously, however far it's away. Thus, on a detecting screen, the previous interference pattern will disappear, and be replaced instead by a clump pattern. Which particular particles caused either of these patterns is irrelevant - you don't need this information to see the patterns they make. All that matters is that you could acquire this information, if you wanted to - it's out there, in the universe.
I don't understand this sentence. You can never be sure of what? If you place a polariser in the path of your signal photon, that you know has a 50% chance of being left-handed and a 50% chance of being right-handed (as you do), and your polariser only allows one or the other through, then you can be 100% certain that the photons that it passes are of one kind of chirality, and the photons it blocks are of the other. This knowledge thereby gives you knowledge that the entangled partners of all these photons have similarly had their chirality possibilities collapsed into one or the other actuality. Blocked or passed. You don't need to know which is which.
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