Is Quantum Entanglement Real?

FIFTY years ago this month, the Irish physicist John Stewart Bell submitted a short, quirky article to a fly-by-night journal titled Physics, Physique, Fizika. He had been too shy to ask his American hosts, whom he was visiting during a sabbatical, to cover the steep page charges at a mainstream journal, the Physical Review. Though the journal he selected folded a few years later, his paper became a blockbuster. Today it is among the most frequently cited physics articles of all time.

Bell’s paper made important claims about quantum entanglement, one of those captivating features of quantum theory that depart strongly from our common sense. Entanglement concerns the behavior of tiny particles, such as electrons, that have interacted in the past and then moved apart. Tickle one particle here, by measuring one of its properties — its position, momentum or “spin” — and its partner should dance, instantaneously, no matter how far away the second particle has traveled.

The key word is “instantaneously.” The entangled particles could be separated across the galaxy, and somehow, according to quantum theory, measurements on one particle should affect the behavior of the far-off twin faster than light could have traveled between them.

Entanglement insults our intuitions about how the world could possibly work. Albert Einstein sneered that if the equations of quantum theory predicted such nonsense, so much the worse for quantum theory. “Spooky actions at a distance,” he huffed to a colleague in 1948.

In his article, Bell demonstrated that quantum theory requires entanglement; the strange connectedness is an inescapable feature of the equations. But Bell’s proof didn’t show that nature behaved that way, only that physicists’ equations did. The question remained: Does quantum entanglement occur in the world?

Well, in the interest of full disclosure, let me first say that I am no longer a working physicist, and haven't been one for a long time. When I was, I was a condensed matter theorist and not a cosmologist or a particle guy. I studied both because I was interested in them, and always thought knowing as much science [in and out of physics] would be useful to being a good low energy physicist. [And, as an aside, the particle guys thought so, too. The so-called "Higgs" mechanism should really be known as the "Anderson" mechanism. The particle guys had, manifestly no problem stealing from condensed matter theorists. The popular press has just had trouble giving credit to the right person... Oh well...]

So, anyway, what I think about it is no more important than what any other well informed layman might think. If you accept that, then here goes:

A lot of people, as you may know, are kind of dubious about the so-called "Inflaton Field." The biggest reason is that it seems completely ad hoc. We have some gross morhology that we can't account for without it. But if this field existed, what happened to it? Oh "spontaneous symmetry breaking." That sounds like a rabbit coming out of, and then going back into a hat to me.

There is, of course, the possibility that it might be an already known field. But that far back, it has to be one we don't know very much about, so, how about the Higgs?

I've always been suspicious of the idea that the Higgs Field might be the Inflaton Field. It strikes me as a "bandwagon effect" argument to get people onboard with the Inflaton Field hypothesis; never a good idea in science. There are some -- to my way of thinking weak -- arguments to suggest that the Higgs is the Inflaton, bnut it has problems. The most serious is that Higgs Inflatons don't preserve Unitarity. This is a deal killer generally in quantum field theory, although there are some hand-waving arguments that it might be possible to get past this. There were some serious reasons for wanting it to be the Higgs: there doesn't seem to be "any room" for yet another field with the right properties in the very, very early universe.

As you probably also know, the uniformity of the CMB as well as large scale fluctuations are explained by Inflation. And we do need some explanation. But, they are also explained by VSL theories.

I'm kind of attracted to VSL theories, because I've always thought the speed of light might very well be a function of the size and shape of the universe in spacetime. It's natural to think of it as a "geometrical" constant because in the metrics of both Minkowski Space and GR it is just a scale-factor between space and time. So to me, there is some appeal of the VSL theories. And since the energies of the early universe are not going to be achieved in any lab any time soon, the only thing we have right now is satisfaction of the known very gross morphology of the current universe and mathematical self-consistency. So I think VSL theories are still on the table.

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