Friday, September 23, 2016

Quantum leaps

I logged on this evening and saw that I had 350 views yesterday and the last 20 or so posts all jumped by 20 views.  That's pretty odd, but welcome...

I've been meaning to post about this cool talk at the library Tuesday evening, and I've finally gotten to it. It was Pedro Goldman speaking on quantum physics. The title of his talk was Music and Schrödinger's Cat: The Weirdness of Reality in Physics.  It was very entertaining, and the turnout was astounding.  They put down more chairs and there still ended up being some people standing in the back.  The professor kept things quite light and only occasionally introduced equations.  Mostly he wanted to talk about some of the really weird aspects of quantum mechanics, such as Schrödinger's Cat and quantum entanglement, but then interestingly he tied the ratios of the electron states to Pythagoras's golden ratio (something that I learned about in Donald Duck in Mathemagic Land many years ago) and how that tied together with music.  He encouraged questions, though it was probably just as well that not too many people asked them, though some were actually pretty good questions.

One person referenced this Bizarro cartoon, which I must admit is quite droll.

The talk went 10 minutes long, but no one seemed to mind.  The professor was really enthusiastic and conveyed some very difficult material well.

I didn't learn a lot that was truly new to me, since as a teenager I had read up on a lot of the issues.  But I had forgotten some of it.  A very small amount of this is in Hawking's A Brief History of Time, but really he is more interested in the Big Bang, cosmology, black holes (obviously) and string theory and spent relatively little time talking about quantum physics.

One thing that I had forgotten is that the fact that electrons cannot inhabit the space between their quantum states seems to be explained by the fact that they are bound by the properties of waves and waves can only have crests that can be counted as discrete units (i.e. integers).  I don't really remember how easy it is to move an electron between these various states (i.e just how much energy does it take), but it probably happens all the time.  I guess the main reason that an electron cannot lose energy and drop below its lowest orbit, is because of the positive charge of the protons in the nucleus.  Can an electron be infused with so much energy that it really can escape its atom as is keeps going out further from the nucleus?  I think probably not -- even when the atoms are split the electrons are supposed to match up to the protons, but that would definitely be something to delve into a bit more.

I actually think a lot about energy transfer and energy levels, since I have to put so much (stored) potential energy into biking home, and even more when biking up to the library.  But that's classical mechanics and doesn't involve quantum physics.  Still, it would be pretty neat to suddenly jump up a level the way an electron basically moves between levels, though I suspect my body wouldn't survive the transition.

The professor talked about quantum entanglement as being one of the spookiest aspects of quantum mechanics.  He mentioned that Einstein actually wrote a paper on the topic, though he mostly wanted to use it to discredit the theory, and in fact some of the wilder aspects were confirmed.  What the professor didn't mention, and what probably was at the heart of Einstein's objections, was that when the particle's position or spin is measured and the superposition collapses, then the entangled particle instantly changes no matter how far apart.  And this appears to mean that information can be transferred at faster than light speeds.  I do wish he had gone a bit more into this, especially if anyone truly believes that this means a universe forks off at each decision point when superposition collapses.*  I would find that essentially impossible to believe.

I think the real issue is whether any of this makes sense above the atomic scale, or even if it is limited to atomic-level reactions, can this be harnessed.  I would probably have been fairly skeptical, but some physicists have been hard at work trying to actual harness quantum entanglement (the phenomenon is still taking place at the atomic level but they are figuring out how to harness this for real-world applications.  Here is a recent piece that describes in somewhat sketchy detail how they are making progress (certainly more than I would have expected).  Amazing!  And now there is more evidence that quantum entanglement is more than just a theoretical construct.  I suppose that this should be a reminder to be a bit more humble about fields that I am sort of skating by on information that I gleaned several decades ago...

The professor sort of joked that you could emulate quantum superposition by knowing that he (the professor) was either inside the room or outside the room in the hallway, but that until you (the observed came down the stairs) it was just the same as if he was in both places at once.  Of course, no one thinks that superposition or even the Heisenberg uncertainty principle apply above the atomic scale, though I suppose I did practice them in my own way.  I ended up giving away cats twice in my life to different friends, and as they (the cats) aged, it was always a curious moment at the end of each call where I could choose to ask about their health.  Before asking, I could picture them alive and in fairly good health, but once I asked I would find out that they had lost more teeth for example or were having to keep going to the vet.  And of course, in all cases, there was a day when the cat had been alive in my imagination (even if I suspected they might be dead), but after asking, I knew that the cat had died.

Anyway, it was a very inspiring talk, though one I might not have appreciated fully had I not been reading up on physics at least a bit over the past few months.

On the way back, I was really trying to make up for lost time (those 10 minutes!) and maybe was stressed about thinking about work that I should have done.  Anyway, I was sort of breaking a bit too hard, and then I hit a kind of pothole on Parliament Street and my left hand reflexively clamped down on the brake, which is a big no-no in cycling .  The back tire started lifting off the ground and it looked like I was going to go over the handlebars.  Somehow I managed to release the brake and steer through a really awkward half-slide/stop.  I pulled over and sort of caught my breath.  Given that there was a car following behind me (fortunately not speeding) it could have been really bad had I suddenly tumbled off my bike right in front of the car.  I sort of imagined a fork in the universes where I had lost control (and been hit by the car) and the one (that did unfold) where I managed to wrestle control back, and after a shake of the head and a reflection on how fortunate I was, I biked the rest of the way home without incident.  I'm certainly glad that I am in this universe and am still able to "observe" it, so it didn't wink out (at least from my perspective) upon my demise.** 

* There is quite a bit of dissension on whether entanglement and other concepts can be adequately explained for a lay audience.  One reviewer suggests Louisa Gilder's "Age of Entanglement" and Brian Greene's "The Fabric of the Cosmos," so I'll at least consider tackling them at some point.

** That's a bit of a weak joke about the strong formulation of the anthropic principle -- that the universe requires some intelligence to observe it or it couldn't exist in the first place, and thus the various settings of the speed of light and gravitational force were "designed" in a way to at some point support life.  I was actually surprised at how much Hawking discussed the anthropic principle in his book, since it feels far more like philosophy than physics to me. 

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