Tuesday, November 3, 2015

SciAm book promotes spooky action

Physicist Sabine Hossenfelder blogs this book review:
Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time -- and What It Means for Black Holes, the Big Bang, and Theories of Everything
By George Musser
Scientific American, To be released November 3, 2015

“Spooky Action at a Distance” explores the question Why aren’t you here? And if you aren’t here, what is it that prevents you from being here? Trying to answer this simple-sounding question leads you down a rabbit hole where you have to discuss the nature of space and time with many-world proponents and philosophers. In his book, George reports back what he’s found down in the rabbit hole.

Locality and non-locality are topics as confusing as controversial, both in- and outside the community, and George’s book is a great introduction to an intriguing development in contemporary physics. It’s a courageous book. I can only imagine how much headache writing it must have been, after I once organized a workshop on nonlocality and realized that no two people could agree on what they even meant with the word. ...

In his book, George lays out how the attitude of scientists towards nonlocality has gone from acceptance to rejection and makes a case that now the pendulum is swinging back to acceptance again. I think he is right that this is the current trend (thus the workshop).
This sums up what is wrong with physics today. Clear-eyed XX century physicists purged the medieval spooky mysticism of nonlocality from science, and now it is back with no one even knowing what it is.

She goes on to say that the book is a confusing mish-mash of buzzwords and personalities, without ever explaining the physics or saying what is accepted:
I found the book somewhat challenging to read because I was constantly trying to translate George’s metaphors back into equations and I didn’t always succeed. But then that’s a general problem I have with popular science books and I can’t blame George for this. I have another complaint though, which his that George covers a lot of different research in rapid succession without adding qualifiers about these research programs’ shortcomings. There’s quantum graphity and string theory and black holes in AdS and causal sets and then there’s many worlds. The reader might be left with the mistaken impression that these topics are somehow all related with each other. ...

For my taste it’s a little too heavy on person-stories, but then that seems to be the style of science writing today.
This sums up what is wrong with popular science writing. SciAm used to be better than this.

A friend of hers wrote the book, and she recommends it. Sigh.

The Wikipedia article on action at a distance is pretty good. It explains how Maxwell developed his electromagnetic theory by seeking to get rid of action at a distance. This was one of the most important intellectual developments of all time.
To date, all experiments testing Bell-type inequalities in situations analogous to the EPR thought experiment have results consistent with the predictions of quantum mechanics, suggesting that local hidden variables theories can be ruled out. Whether or not this is interpreted as evidence for nonlocality depends on one's interpretation of quantum mechanics.
That's right. You can interpret quantum mechanics to give a scientific causal view of the world, or you can interpret it to allow for unverifiable spooky actions. Your choice. Apparently the current trend among physicists and popular science writers is for the latter.

Lawrence M. Krauss has a pretty good entanglement article in the latest New Yorker mag:
No area of physics causes more confusion, not just among the general public but also among physicists, than quantum mechanics. On the one hand, it’s the source of New Age mythology, and has enabled hucksters to peddle new self-help cures; on the other, for the philosophically inclined, it has provided some illusory hope of free will in an otherwise deterministic universe. Of the aspects of quantum mechanics that confuse and dismay observers, perhaps nothing approaches the property called “entanglement.” Einstein, who never really accepted entanglement’s existence, called it, derisively, “spooky action at a distance.”

Unfortunately for Einstein, entanglement, “spooky” or not, is apparently real, as researchers in the Netherlands demonstrated last week, just in time for Halloween. In doing so, the researchers affirmed once again that quantum mechanics, as strange as it may seem, works in every way we can test it.
Yes, physicists themselves cannot agree on whether entanglement is spooky.

He attacks the essay I cited last week:
Similarly, last week, the Pulitzer prize-winning writer Marilynne Robinson published an essay in which she challenges the nature and relevance of modern science. The essay argued that entanglement “raises fundamental questions about time and space, and therefore about causality.” She went on to say that this called into question the ability of science to explain reality as a whole. It’s easy to understand how Robinson arrived at this incorrect idea: when a measurement of one electron here can instantaneously affect the measurement of another electron on the opposite side of the universe, faster than the speed of light, it does seem as though causality has been thrown out the window.
Yes, fundamental questions about causality would be raised if the "measurement of one electron here can instantaneously affect the measurement of another electron on the opposite side of the universe". But it cannot.

Krauss's explanation is above average, but defective:
As long as the two electrons remain entangled, then this link endures — even if they are separated across the galaxy. If I measure one electron in my lab, the second electron is affected by the measurement of the first electron with no time delay — instantaneously — even though a signal travelling at the speed of light would take millenia to cross the distance between them.

That instantaneous link is the “spooky action at a distance” of which Einstein was so skeptical.
No, measuring an electron does not affect a distant electron.

Quantum mechanics gives a mathematical representation of the electron pair, and a way of making probabilistic predictions about spin. Measuring one electron does affect the prediction being made for the other. But the math is not the same as the physics. The actual electrons may be deterministic and separable.

Spooky action at a distance was debated by physicists in the time of Newton, of Maxwell, and of Bohr and Einstein. I thought that mainstream physics was solidly convinced that no such thing exists. Maybe that was true 50 years ago. What happened? Why have all these otherwise-hard-headed guys gone mushy about physics that perfected in 1930? Physics is in a sorry state when you have to read the Lubos Motl blog or my own to find something sensible on this subject.


  1. This comment has been removed by the author.

  2. Bell's Theorem is simple set theory, but rubbish physics. Entanglement is a mathematical fiction that is good enough to calculate QM statistics, but does not represent physical reality. Joy Christian has shown (in 2007) that Bell's error is a mistaken 3D topology. Quaternion math is necessary to model 3D statistics which Bell cavalierly consigned to a 1D formula. Physics has been on a bogus 50-year detour. Wake up !!

  3. You wrote: "The actual electrons may be deterministic and separable." Could you explain how, for example, the electrons in the classic EPR (Bohm) experiment could give results consistent with quantum mechanics, and still be deterministic and separable? Yes, there is always the possibility of what's called super-determinism, but I think you've dismissed that as a bizarre idea with few followers, so I assume you have something else in mind. Could you explain what you have in mind?

  4. I am just trying to defend conventional quantum mechanics, but it is confusing, and I will try to post a better explanation.

  5. Conventional quantum mechanics entails the violation of Bell's inequality, whereas from the assumptions of determinism and separability of the test electrons (implying counterfactual definiteness) and free independent choices for the measurement angles (no "bizarre" super-determinism) it follows by simple algebra that Bell's inequality cannot be violated. This is why people say that if we accept conventional quantum mechanics we need to give up one of these deeply held beliefs. As even Schrodinger ultimately admitted, we can't get rid of "these damned leaps" (with apologies to your blog motto).