Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Friday, November 13, 2020

Spooky action, weeping angels, and quantum physics

One of the reasons I get so impatient with woo-woos is that science is plenty cool enough without making shit up.

Today we'll take a look at two examples of this from the field of quantum physics.  Because quantum physics is plenty weird even without any embellishment or misinterpretation, it's been particularly prone to being co-opted by woo-woos in their search for explanations supporting (choose one or more of the following):
  • homeopathy
  • psychic abilities
  • astrology
  • the soul
  • "chakras" and "qi"
  • auras
But you don't need to do any of this to make quantum physics cool.  Let's start with an experiment regarding "quantum entanglement" -- the linking of two particles in a state describable by a single wave function.  While this might seem uninteresting at first, what it implies is that altering the spin state of particle A would instantaneously change the spin state of its entangled partner, particle B -- regardless of how far apart the two were.  It's almost as if the two were engaging in faster-than-light communication.

There is a further twist on this, and that's where things get even more interesting.  Most physicists couple the entanglement phenomenon with the idea of "local realism" -- that the two particles' spin must have been pointing in some direction prior to measurement, even if we didn't know what it was.  Thus, the two entangled particles might have "agreed" (to use an admittedly anthropomorphic term) on what the spin direction would be prior to being separated, simulating communication where there was none, and preserving Einstein's idea that the theories of relativity prohibit faster-than-light communication.

Scientists at Delft University of Technology in the Netherlands have closed that loophole.  Using an extremely fast random number generator, they have altered the spin state of one of two entangled particles separated by 1.3 kilometers, and measured the effect on its partner.  The distance makes it impossible for sub-light-speed communication between the two.  This tosses out the idea of local realism; if the experiment's results hold -- and they certainly seem to be doing so -- the particles were indeed communicating faster than light, something that isn't supposed to be possible.  Einstein was so repelled by this idea that he called it "spooky action at a distance."

To quote the press release:
With the help of ICFO’s quantum random number generators, the Delft experiment gives a nearly perfect disproof of Einstein's world-view, in which "nothing travels faster than light" and “God does not play dice.”  At least one of these statements must be wrong.  The laws that govern the Universe may indeed be a throw of the dice.
If this wasn't weird and cool enough, a second experiment performed right here at Cornell University supported one of the weirdest results of quantum theory -- that a system cannot change while you're watching it.

Graduate students Yogesh Patil and Srivatsan K. Chakram cooled about a billion atoms of rubidium to a fraction of a degree above absolute zero, and suspended them between lasers.  Under such conditions, the atoms formed an orderly crystal lattice.  But because of an effect called "quantum tunneling," even though the atoms were cold -- and thus nearly motionless -- they could shift positions in the lattice, leading to the result that any given atom could be anywhere in the lattice at any time.

Patel and Chakram found that you can stop this effect simply by observing the atoms.

This is the best experimental verification yet of what's been nicknamed the "Quantum Zeno effect," after the Greek philosopher who said that motion was impossible because anyone moving from Point A to Point B would have to cross half the distance, then half the remaining distance, then half again, and so on ad infinitum -- and thus would never arrive.  Motion, Zeno said, was therefore an illusion.

"This is the first observation of the Quantum Zeno effect by real space measurement of atomic motion," lab director Mukund Vengalattore said.  "Also, due to the high degree of control we've been able to demonstrate in our experiments, we can gradually 'tune' the manner in which we observe these atoms.  Using this tuning, we've also been able to demonstrate an effect called 'emergent classicality' in this quantum system."

Myself, I'm not reminded so much of Zeno as I am of another thing that doesn't move while you watch it:



See what I mean?   You don't need to add all sorts of woo-woo nonsense to this stuff to make it fascinating.  It's cool enough on its own, although throwing in a Doctor Who reference does give it an extra special frisson.

Of course, the problem is, understanding it takes some serious effort.  Physics is awesome, but it's not easy.  All of which supports a contention I've had for years; that woo-wooism is, at its heart, based in laziness.

Me, I'd rather work a little harder and understand reality as it is.  Even if it leaves me afraid to blink.

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This week's Skeptophilia book-of-the-week is about our much maligned and poorly-understood cousins, the Neanderthals.

In Rebecca Wragg Sykes's new book Kindred: Neanderthal Life, Love, Death, and Art we learn that our comic-book picture of these prehistoric relatives of Homo sapiens were far from the primitive, leopard-skin-wearing brutes depicted in movies and fiction.  They had culture -- they made amazingly evocative and sophisticated art, buried their dead with rituals we can still see traces of, and most likely had both music and language.  Interestingly, they interbred with more modern Homo sapiens over a long period of time -- DNA analysis of humans today show that a great many of us (myself included) carry around significant numbers of Neanderthal genetic markers.

It's a revealing look at our nearest recent relatives, who were the dominant primate species in the northern parts of Eurasia for a hundred thousand years.  If you want to find out more about these mysterious hominins -- some of whom were our direct ancestors -- you need to read Sykes's book.  It's brilliant.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]




1 comment:

  1. I have so many questions as an average person. For instance; how do you find two entangled particles? Are they always paired off? How do you separate them? I love this stuff!

    ReplyDelete