Happy St. Puketricks Day or St. Pooka-tricks Day!

Hello all, however few of you there may be!
Depending on your proclivities, please have a Happy St. Puketricks Day or St. Pooka-tricks Day!
Well, to be more straightforward and "normal" (ugh) I could just say "Happy St. Patrick's Day" to everyone.

Enjoy/celebrate; don't drink too "liberally" I beseech ...

PS: Look up pooka/pookah/púca on the Internet etc. for fun ...

Open forum: dish against or defend many-worlds and decoherence theories

Over time I've left many remarks (and many very recently) critical of many-worlds and decoherence theories at blogs such as Uncertain Principles, Quantum Pontiff, etc. I can be at bit of an irritant so I don't want to wear out the OPs that I criticize, many of whom indeed don't have time to follow up on my depredations. Here's a forum to discuss the problems of such theories, especially if you were debating with me at another blog. Do also check the previous post about "quantum stupefaction" which is sort of silly, yet may have actual implications for MW concepts and related.

"Quantum Stupefaction" pwns Many-Worlds!

This is adapted from my comments to a thread about MW and morality going on at Uncertain Principles as well as a post to sci.physics, alt.fan.rawilson etc:

First, let me explain "quantum suicide" (c.f. quantum immortality, check Wikipedia. Later, I explain something even more perplexing.) If we imagine that only your conscious selves serve as possible carriers of what "you observe" as you split up into "many worlds", then you can do this: Set up the Schrödinger's cat experiment with yourself inside. That means, a radioactive nucleus decaying will cause HCN to flood the chamber, so the decay and you dying from it is a chance event and "not determined" by classical physics. In the many-worlds theory, each moment means the splitting of the universe into other universes representing possible outcomes (such as did or did not decay.) Robert Anton Wilson wrote about Everett-Wheeler MW theory, among other things, in the speculative/fabulist fiction work Schrodinger's Cat Trilogy.

Well, there is always a chance you will survive even after many half-lives of the death-dealing source. Hence there are always some "yous" which can enter some "branches" of MW. Sure, "you" die most of the time but the conscious survivors are the ones saying "Hey, here I still am after all this time." Hence you can never die! If you get into the chamber, you will always "still be there" wondering WTH happened and how you survived millions of half-lives of an unstable nucleus. You can even walk out later, by having a temporary period for the nucleus to be allowed to affect the death-dealing device.

BTW this does not depend on whether consciousness collapses WFs or is "weird" since any sentient being can only notice its survival, right? It is eerily reminiscent of the "multiverse" (that has differing physical constants like alpha) idea of explaining anthropic fine-tuning. However, I think that outcome ruins the whole "proportional" argument that sophistrizing MW advocates put out to imply that each of us has the same "expectation" of outcomes in MW as in ordinary collapse. (BTW I believe "decoherence" is a failed, circular argument for making "apparent" collapse work out OK. Note that use of "apparent" yadda is a warning sign of post-modern psychobabble.)

Note, it is quite possible to build this device. I challenge any supporter of MW to have the balls/etc. to actually get in one. We can even arrange a cash prize waiting outside of $10,000,000 or so, that you can only collect when the temporary danger period is over. Since we might set up a chance of only say 1:10,000,000 of a "you" getting out alive after the danger period, it is an eminently reasonable bet for the rest of us. But since you expect to experience surviving and winning, why not show your "faith" in MW and come out a multi-millionaire to boot? Not only that, but you can see the amazed expressions of the versions of us that see you walk out alive! We'd never live it down, heh.

Well, that's already rather weird, but let's take it further into the twilight zone: Suppose we change the quantum suicide scheme so it doesn't actually kill you if the agent nucleus decays. Let's say, it injects you with something causing total but temporary unconsciousness. Let's call this "quantum stupefaction" ;-) Well, the logic regarding "awareness" should work the same way at first. "I" expect to be one of the tiny minority that remains awake and knows it, for how can that be "experienced" any differently than if most of me actually died?

Yet after awhile, all the other me`s start waking up and there are so many more of them then those who never got put to sleep. So, now what? If "I" can "expect" to be able to say, "How fortunate, I didn't even have to become unconscious" what then takes over the expectations when the others wake up? So what do I really have to "likely" look forward to: not even being knocked out at all, or being put asleep and then waking up? The first option follows the original logic of quantum suicide, but the latter follows what we expect from the total chance of being put asleep and then waking up. Quantum [non-]Suicide was at least a potentially viable if wacky notion, but I think this further refinement makes the whole idea (and by extension, many-worlds "theory") look silly.

Here's a paradox about work-driven buildup of mass and conservation of angular momentum. Give it a try.

In everyday mechanics, in order to redistribute mass we have to actually move it from one place to another. However, the equivalency of mass and energy complicates that issue. For example, we could convert the impact energy U (I use U so E can be a field) of a falling mass m1 hitting the floor into mass m2: m2 = m1gh/c^2. Hence potential energy can of course be converted into mass, not just actual energy. Note that we could violate conservation of angular momentum (sum of r cross p) if we could just shift mass effortlessly (no forces, like "teleportation") even if the total did stay the same. That's because in a frame of ref. where the mass is moving, its linear momentum vector would be shifted sideways to itself. (Thus changing the r cross p with no compensation.)

I am aware of various sorts of compensation etc. in apparently paradoxical situations, but I imagined a thought experiment that I can't solve to maintain CoAM. Have a line charge along "x." Have also two square "solenoids" S1 and S2 with same sense of current and sides equal to Y. All three lie in the same plane, with one solenoid centered at coordinate y1 and the other at y2 = -y1. (Being lazy at constructing ASCII diagrams has sharpened my verbal descriptions.) One one side of each solenoid , the current is being "pushed" in the direction of field E, and on the other, the current is fighting against E. It helps the following if you imagine not a literal current of electrons, but a mechanically driven belt of little charged bodies: On the side of each where E is favorable to the "current ", mass-energy builds up at a rate dm/dt = IEY/c^2. On the unfavorable side, mass-energy is lost at a rate dm/dt = -IEY/c^2 (if abs. vals used for the variables.) That already looks like a problem per the previous discussion, but we usually consider such issues solved by the AM etc. of the fields. (Note Feynman's paradox of the charged wheel, etc.) Some say there's an "energy current" between the sides (see Taylor/Wheeler, Spacetime Physics etc.) , but how does that really work?

However, the real test (?) of there being a problem is whether it is reversible. Hence, let's move S1 and S2 respectively away from the line charge at low velocity. Now, once they're accelerated, we have for the rate of change of angular momentum L: dL/dt = rv dm/dt, using proper signs in vector notation. If you check, you'll find that there's a net change of L as S1 and S2 move to a distance from the line (same sign of build ups at opposite sides as seen by observer looking at plane, times opposite r and v, gives same dL/dt for S1 and S2.) I can't find an influence on the wire from their motion that would compensate the right amount. Then, at a distance, you can switch the direction of current in the solenoids and again no net effect. Then, move S1 and S2 towards the line charge, and reversed dm/dt and reversed v makes the same dL/dt as before. Lather, rinse, repeat; I don't yet see how to foil it.

Give solving it a try, you may even get help from offbeat angles like stress corrections in the solenoids etc.

Happy Saint Patrick's Day!

Have fun, but take care of yourself and everybody else ...

It's Talk Like a Physicist Day!

Greetings ....

Well, (in my time zone, folks, and still in many others!) it's Talk Like a Physicist Day, Pi day, Bee writes about the PI gym (at the Perimeter Institute) albeit two days earlier, and Albert Einstein's 129th birthday! First, one cool way to talk like a physicist is to never refer directly to "zero" or "one." Instead, say the quantity is vanishingly small, or vanishes, and say "unity" instead of "one."

Second, here's the weird little story I heard years ago about someone who got in trouble for talking like a physicist, and was one as well (assuming it really happened ...): If you run a red light and it goes to court, beware of trying the apocryphal (?) tack of claiming that Doppler blue shift made the red light look green (or yellow.) Supposedly the physicist who posed that excuse some years ago faced a scientifically literate judge, to his dismay. The judge calculated that the driver had to be going around 100,000,000 mph, and fined him accordingly! It’s not always wise or clever to talk like a physicist, even if you are one.
(Does anyone remember when/where they head that one?)

A quantum measurement paradox: the reallocation by measurement problem

I spend lots of time thinking about weird foundational issues in quantum mechanics (I used to be in top Google hit for "quantum measurement paradox"), and do I have a deal for anyone else like me. I have been thinking of this problem for awhile, and the post Many Worlds, Many Headaches on Uncertain Principles stimulated me to post a version of it. If you want something really strange and "after the fact" about measurement, please consider my following proposal: In a Mach-Zehnder interferometer, insert a gray filter G into leg L2. Given a traditional stream of light, that alters the amplitudes delivered to the beam-splitter/recombiner R. With a 25% transmitting filter, the L2 amplitude is 0.5 of that in L1 (which itself is sqrt (0.5) of the original pre-split input.) Hence, with symmetrical R, we get an output mix rather than all A channel output. We can adjust R to a compensatory split so that output is again all A channel. Using individual photons, the statistics should be the same. FEL optical physicist Michelle Shinn of J-Lab agreed with me that's so, despite the weirdness of the photon's wave function in L2 being attenuated by the chance that it could have been absorbed, even if it wasn't (well, superposition of absorption and not-absorption in the dye molecules in the filter, etc, right?) Also, as G gets darker, this has to be the limiting factor approaching the results of an opaque stop in L2. But what happens if we can find out whether a photon has been absorbed in the filter?

Consider an opaque stop: the stop clearly "reallocates" the WF all into L1, in a manner akin to the Renninger negative result problem, even though no actual "measurement" is taken। But there, a photon will just never get through. However, G may or may not absorb a photon, something we can in principle check on (There are semi-transparent optical detectors, no? Just consider film for example.) Now, while G is still "deciding" (in a state of superposition) whether it will absorb or not, it makes sense to consider the L2 wave to be attenuated relative to L1. Maybe that's the normal time scale to allow interference in R before that happens. But, after a certain time, if we check G carefully to look for evidence of absorption, it should be settled: absorption or not. If it did, there's no paradox. But if we find "no absorption," why in the world should the L2 wave continue attenuated? The measurement result was "no" for G, so there is no longer "a chance" that the photon might end up there. The filter might as well have been clear glass, right? If so, then the interference at R would be different (it would follow normal equal-balance rules instead.)

The really weird thing is, that reallocation should take place as soon as the absorption/detection issue is settled. If so, we could manipulate the pattern of hits (with sequential photon shots) at the output by looking for evidence of absorption in the filter, which would start rearranging the WF as per Renninger etc. In principle, there's nothing to stop this from being a true FTL signal, since manipulating G (or perhaps the distance to R) causes noticeable effects (not distant signal correlations) at R. Sure, that's problematical, but you can't just blow off the supposed effect on the WF of the negative measurement in G, can you? Have fun.
(I also just put this up on sci.optics, sci.physics, etc.)