From your link. So either Schrödinger's cat is alive or dead before it's observed, or spooky action at a distance occurs. You can't have both. Just saying one particle is observed but the other was initially it's opposite has to address the problem of the particle having spin before it was observed. [Hopefully I have that gist right even if I mucked up any details.]
Right, the cat is both alive and dead before it's observed. It's in superposition. In the case of the photon polarization, the photon is also in superposition, a mix of polarizatiom states. When Alice looks at her photon, there is 50/50 chance of vertical, and a 50/50 chance of horizontal. The result is entirely probabilistic and essentially random. But when Alice looks, she collapses the wave function of both her photon and Bob's photon, even if Bob is on the other side of the universe. That's spooky action at a distance. You can't, however, harness this spookiness to send a FTL signal, so special relativity remains intact. Of course, again, if you drop the wave function collapse postulate, there is no spooky action at distance. There are just parallel universes: There is one universe in which Alice gets horizontal and Bob gets vertical. In a different universe, there is a different version of Alice in which she gets vertical and Bob gets horizontal. However, there is no universe at which they both get horizontal or both get vertical. There is no spooky action at a distance, just different worlds with outcomes that can be calculated in advance.
"Collapses the wave function" without crossing the distance seems like double talk. I understand what is meant, and how it explains the double slit experiment results. But I'm not convinced labeling the event means physicists understand what is going on. I have not said this was a means of achieving FTL travel or exchange of information. My argument was and is, there are still enough unknowns out there that declaring the answer in and absolute is not consistent with the scientific process.
Science could pretty well rule out that clacking your heels three times while chanting, "There's no place like home" is not the solution to FTL travel. Similarly, science can also pretty well rule out that FTL travel can be achieved by any means that involves a path that continually maps to a continuous path through normal space, an assumption which characterizes all the variations of "warp drive". What it does not rule out is wormholes and "jump drives", which appear as discontinuities between source and destination in normal space, without the craft ever passing through intermediate points in normal space (except as intermediate stops, in which case tou apply the definition to the individual jumps). But if you can subdivide the path infinitely to describe a continuous path through normal space, your theory will not fly). It also does not rule out theories which involve neither of the above models, whatever those theories may be. The scientific process doesn't throw away existing theories. It refines them and finds the conditions that fall outside the existing theories; assumptions. As in criminal law, ignorance of the laws is no excuse.
I don't buy your analogy, Cog. I get it but I don't think it's analogous to compare evidence-less based fiction with the conclusion, we know enough about the Universe to make absolute statements such as, we know X absolutely.
I won't argue with you, Ginger. You never yield, and your response shows you have missed my point completely.
False on both counts. From the Free Dictionary: Clicking one's heels to travel is not a scientific fact, therefore it is not analogous.
You're right. Clicking ones heels does not imply specific mechanistic criteria that can be invalidated. So heel-clicking is a more pausible means of FTL travel.
You think because you don't post a convincing argument that it must be me, not you, where the problem lies. You didn't address what I said which was your analogy failed because it compared scientific fact (what we know about FTL) with fictional premise (a scene from a fictional book/movie). They are not analogous. May I assume you recognize your analogy failed and now you are taking a different approach? Am I correct in that you are now claiming something completely fictional is more plausible than the possibility of a broader understanding of FTL might possibly include a mechanism to exceed it? I don't want to be arguing against a straw man. Time and time again things that have been considered scientific fact have been refuted when more evidence was uncovered. Plate Tectonics, Miasma, H-Pylori, even Special Relativity itself replaced previous scientific 'facts'. So let's look at that last scientific fact in terms of laws of physics: So, after Einstein, one of Newton's laws of physics was discarded. My point is only that one needs to always keep this in mind when making statements that scientific facts are absolute and unalterable.
I don't think anyone is arguing that science consists of absolutes or iron-clad proofs. In fact it can't, because it proceeds by induction, and the only absolute truths are those of deduction; i.e., in the way of proven mathematical formulations or logically sound and valid arguments. That said, the issue of the opening post is finding a way to harness quantum entanglement and dark matter for FTL travel, and according to current science this attempt is hopeless. Perhaps that science will change at same later date, but just because science can and does change, doesn't warrant the belief that just about any concept, if we wait around long enough, will be validated. Evolutionary theory isn't absolutely true beyond any possibility of doubt either, but I'd wager dollars to donuts that in the far future, it will still be valid (even if updated) while intelligent design will never be valid. You might also recall the post I made on the pessimistic meta-induction. So yes, scientific conclusions are tentative and defeasible, but at the same time, lots and lots of stuff will never be scientifically valid, even as theories change. BTW, all three of Newton's laws are strictly false on quantum mechanics, and quantum mechanics is probably the most solid theory ever developed.
It may sound like double talk, but this has been standard physics for nearly a century, and the instantaneous correlation of quantum entangled particles has been repeatedly demonstrated without a single instance of the event not happening. Again, however, having said that, Hugh Everett in 1957 wrote a paper essentially dismissing wave function collapse as double talk -- as nonexistent, in fact -- and under his relative state formulation there is no spooky action at a distance, no wave function collapse, no quantum indeterminism and realism is restored to physics, the idea that there is a mind-independent reality and scientists aren't just popping things into existence when they make measurements in the two-slit experiment, for instance.
Edward sounds pretty absolutey to me and as you can see, from the beginning of this 4 page discussion, it's one thing in particular I was addressing. [Waves, "Choir here."] Please don't get the idea I am questioning standard physics. I most certainly am not. What I wrote was not intended to argue your points, only that there are a couple of commonly used models in physics that I find inadequate. I have no quarrel with the models as far as the 'standard physics' goes. I just have a couple issues with the models that despite being standard physics, I can't help but notice the problems with the models. A wave that exists in 3D space but contradicts 3D principles is one of them. The other is the 2D model of a balloon surface that represents a 3D expanding space. I'm unclear why one cannot build a 3D model. I get it re the expansion thing, and I get it re the no center and no edge. It's the model I have trouble with when it comes to the no center and no edge. They are not really addressed by the 2D model. The 'no center' is easy to see on a 2D surface, but it has trouble in a 3D model. And the 'no edge' representation in the 2D model only works if the Universe doubles back on itself and we don't know if that is right. But I digress....
I think Edward is saying that physicists have a fairly good idea of what's going on when it comes to quantum entanglement. I don't see anything wrong with that. So your problem is with modern physics and how it's used to explain certain things?
He had the opportunity to say that. What did I post that contradicted your paraphrasing? No, and I said no such thing.
Then what do you mean when you say you find certain models of physics inadequate? I'm not really sure what the problem is. Some of the people here gave you what I assume are correct answers regarding quantum entanglement, and I think their explanations were more than adequate.
I meant exactly what I said. Did you read my post or just jump to confirm your bias conclusion that I'm naive? A wave that exists in 3D space but contradicts 3D principles is a problem. It's fine the equations work, the explanation "wave function collapses" is peachy. But conceptualizing said waveform while ignoring the problem when you apply the model to 3D (4D if you want to add in time) space is a problem. The other is the 2D model of a balloon surface that represents a 3D expanding space. I'm unclear why one cannot build a 3D model. I get it re the expansion thing, and I get it re the no center and no edge. It's the model I have trouble with when it comes to the no center and no edge. They are not really addressed by the 2D model. The 'no center' is easy to see on a 2D surface, but it has trouble in a 3D model. And the 'no edge' representation in the 2D model only works if the Universe doubles back on itself and we don't know if that is right. I have no problem accepting the fact the Universe is expanding into nothing (as far as we know). I get it the Universe has no center and no edge according to the evidence. Build me a 3D model of it. Explain to me why you can't do that? I can see the 2D model. I get it. But it has problems when you try to build that 3D model. Even an edge expanding into nothing is still an edge. Don't assume by my questions that you have some superior knowledge. You don't, at least not when it comes to these basics. I like the concept that time is the center and the edge. The past is the center and the future is the edge. It's just a conceptualization I contemplate from time to time (oh my the puns). Stop assuming I'm ignorant or a flake. You might find my posts don't say what you imagine they say.
I'm not implying that you're naive or anything like that. I just wanted some clarification, that's all. Don't be so defensive. Isn't the universe flat? So why would we need a 3d model? That wasn't my intention at all. I don't think my posts were hostile in any way, but if they were, I apologize. I just wanted you to clarify your position, nothing more.
It's not so much your posts are hostile, @thirdwind. It's that more than a few people in this forum have for very biased reasons make repeated false assumptions about me and my scientific expertise. You did ask a question that was already answered in the post that led you to ask, leading me to think instead of reading the post you jumped to the conclusion I was challenging mainstream physics. I was not. Was there something I said in post #91 that offered anything new that wasn't in post #87? Moving on... A flat Universe, you say, hmmm, do I or do I not want to delve into yet another branch of cosmology? Maybe after another beer.
A flat universe, which is indicated by sky mapping in the last decade, is a universe that is spatially infinite. The alternatives are positive and negative curvature. A positively curved universe is one in which if you traveled far enough, you would return to where you started, much like circumnavigating the earth. A negative curvature would imply a kind of saddle shape. Since the universe now seems to be spatially infinite, it means that the observable universe, the light from which has had time to reach our eyes, is infinitesimal (actually nothing at all) compared to a spatially infinite universe. An interesting consequence of a spatially infinite universe is as follows: in a spatially infinite universe, anything with a nonzero chance of happening, no matter how vanishingly small the odds of it happening are, will happen an infinite number of times. Since we know that life has a nonzero chance of happening, since it happened here, in a spatially infinite universe there should be an infinite number of inhabited planets, no matter how unlikely life is, and an infinite number of duplicate or near-duplicate planet earths.
If the universe is spatially infinite, which it seems to be, all these inhabited planets are in our universe. They're just not in our observable universe, since what we can see of the infinite universe is limited to a minuscule slice of it in which the light from distant galaxies had had time to reach our eyes.
I thought the size of the Universe was estimated by some cosmologist based on the time since the Big Bang? I'll look it up.
I only skimmed through the last few pages, so apologies if I miss something or rehash old stuff. The problem with thinking about wavefunctions collapsing is that they don't actually collapse. They continue to evolve. One major reason for this is that collapse would have to occur instantaneously, which violates what we know about physics. I think people's conception of collapse comes from the Copenhagen interpretation, which is perhaps the most common, though incorrect, interpretation out there. As far as our universe is concerned, we assume it be to infinite because it makes calculations a lot easier. Whether or not it's actually infinite is unknown at this point in time. There are several models about how a finite universe behaves close to its edge, but these theories are speculation. Theory is probably not even the right word. These models are more like hypotheses. Going back to the first post, you don't have to explain how FTL travel works. I can't speak for all readers, but this one right here doesn't care about explanations. I just want a good story.
The universe can be spatially infinite, even with a big bang. A lot of this stuff is counterintuitive, which naturally leads to confusion. As to the assumption of infinite space, it's no longer an assumption. Sky-mapping surveys in the last decade found strong empirical evidence that the universe is spatially infinite, rather than finite but unbounded (positive or negative curvature). As to wave function collapse, I think you're right. There is no collapse. When you remove the collapse postulate, you get a fully deterministic, local and realistic universe continuously evolving according to the Schroedinger wave equation. Of course you also get the Many Worlds, in which everything that can happen, does happen, just in different branches of the so-called quantum multiverse.
I have to run, I'll be back but here's where my quest starts re calculating the finite size of the Universe: http://arxiv.org/pdf/1106.3366v1.pdf I don't profess to read physics at this level but I thought other readers in the thread would appreciate the original source for how the size was calculated.
