121–130 of 218 posts
On what premise? 'Theories' are human constructs, hence why physicist are so adamant about their Truth and Beauty. It's wrong to say that, when most sciences rely heavily on Occam's principle (an aesthetic argument) for reasons unknown. It's pretty likely that the human brain is guided by both principles to model the world, and that should be reflected in the formulation of our theories.
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I wonder if some rich people could start a form of charity where they just pay a few incredibly brilliant people a good salary to go do whatever research they want for the rest of their lives. Sort of like patronage. Just bypass the whole grant funding cycle and work on whatever you want, because you're a genius and want to study things other people don't like or understand.
The problem with education/science/welfare by charity is that it doesn't scale as well and isn't as stable as societal contracts. A developed country can be recognised by the fact that the society doesn't rely on the goodwill of the rich.
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https://en.wikipedia.org/wiki/Fine-structure_constant#Measur...
Exactly. Its value comes from being measured.
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That language is why I think the authors aren't aware that they are advocating many worlds. Also, this is a fantastic example of the "don't ask questions" attitude I think is so shameful. If they had bothered to take the small step of asking, they'd have come to a clear, evidence-based refutation of Copenhagen! There are regions of spacetime after the measurement, where the wavefunction is not collapsed, which the au…
The point is that the order of the measurements is irrelevant: QM predicts the same probability distribution of outcomes. So the problem can be solved using either order and the response is the same. I am not sure what premise of Copenhagen is being contradicted. Edit: solving the problem in the "natural" order would give the same probabilities but is much more difficult to handle. You need to get a probabilistic out…
Before measurement, the state of the particle system is Σ α_i|i>. Copenhagen says, "after you measure the system, all but one of the α_i go to zero". The authors don't do that, and in fact say that you can't. Unless I am misunderstanding something, they keep all the α_i around at all times and project the measurement for each particle separately, regardless of whether it has been (or will be) measured somewhere else. There is nothing philosophically or physically wrong with this, as they point out, but it is different than what Copenhagen says you should do when you measure something.
And if you look at what it means (which they refuse to do), you'll see that after Alice makes her measurement, Bob's quantum state is still explainable in terms of a superposition. When is the measurement (joint or individual) "finished"? Answer, per the authors: Never. The superposition permeates spacetime. That's how we escape the need for a causal connection between Alice and Bob's measurements, and, naturally, that's how many worlds does it.
(And if we take it further and ask, when Bob makes his measurement, "What is the state of Alice's particles?" we'll see that she is in a superposition of being entangled with each of the superpositions of the particle, which remains in superposition before, throughout, and after our ~measurement of~ entanglement with it).
Btw, something to think on. Consider this slowdown in physics, and the oft-repeated ideas that we'll sure to colonize not just the solar system, but eventually even the galaxy... E.g.: http://www.antipope.org/charlie/blog-static/2007/06/the_high...
They also mention a wildly optimistic "I'm not holding my breath" $20k per kg to mars, which is already is 4x higher than a SpaceX BFR launching stuff to mars.
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This is one of the best arguments for UBI. Imagine how much humanity would innovate in science, open source and other public gift economies if everyone didn’t have to worry how they will eat and pay rent next month.
The argument you are making assumes two things that strike me as highly implausible: (1) That enough people would use their new free time to innovate instead of just watching TV or playing World of Warcraft or something like that. (2) That enough people would still choose to do the unpleasant but necessary tasks that provide the resources needed for everyone to eat, have housing, etc. Not to mention all the other stu…
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The point is that the order of the measurements is irrelevant: QM predicts the same probability distribution of outcomes. So the problem can be solved using either order and the response is the same. I am not sure what premise of Copenhagen is being contradicted. Edit: solving the problem in the "natural" order would give the same probabilities but is much more difficult to handle. You need to get a probabilistic out…
> I am not sure what premise of Copenhagen is being contradicted. Before measurement, the state of the particle system is Σ α_i|i>. Copenhagen says, "after you measure the system, all but one of the α_i go to zero". The authors don't do that, and in fact say that you can't. Unless I am misunderstanding something, they keep all the α_i around at all times and project the measurement for each particle separately, regar…
What he shows in that paper is that the order of the measurments is irrelevant [1]. So he does solve the problem in the reverse order where it can be done easily writing a few quantum states [2].
Note that QM is not about causal connections, is about correlation. Once a pair is correlated, the correlation may appear when measurements are done. But it's not that observing one outcome here and now "causes" a particular outcome there and later (or before). One doesn't need to keep superpositions to think it "correlation" terms (instead of "causal" terms).
[1] Using the projection postulate in the derivation: "Say we have indeed measured on B and got OB = bJ . The state then collapses onto ..." He concludes: "None of this looks very surprising, but we want to stress that the total probability to find OA = aI and OB = bJ does not depend on the place or time at which the measurements occur."
[2] He also uses the projection postulate here in the usual way: "So the experimental outcome (encoded in the combined measurement outcomes) is bound to be the same even if we would measure the idler photon earlier, i.e. before the signal photon by shortening the optical path length of the downwards configuration. Then, if the idler is detected at D4 for example, the above state ‘collapses’ onto ..."
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Copenhagen does not require nonlocality
No, but if you have non-locality, then you don’t need the non-definiteness of Copenhagen, and could do with something like a Bohm or MW interpretation.
I found this quote from David Lindley in a review of Adam Becker's book referenced in this thead (http://www.math.columbia.edu/~woit/wordpress/?p=10147):
"The problem with Copenhagen is that it leaves measurement unexplained; how does a measurement select one outcome from many? Everett’s proposal keeps all outcomes alive, but this simply substitutes one problem for another: how does a measurement split apart parallel outcomes that were previously in intimate contact? In neither case is the physical mechanism of measurement accounted for; both employ sleight of hand at the crucial moment."
Love this comment left on the post by Peter Shor (of Shor's algorithm--the algorithm that kicked off the quantum computing frenzy). I assume it's him and not an imposter. "It's not just that scientists don't want to move their butts, although that's undoubtedly part of it. It's also that they can't. In today's university funding system, you need grants (well, maybe you don't truly need them once you have tenure, but…
One slightly cynical strategy I've heard is that your next grant proposal should be for the work you've already completed, giving you time to come up with the idea for the one after :)
What people however do is to smuggle more risky ideas into proposals for less risky ones. But that in the end means they'll be spending time also on low-risk things.