Thursday, November 10, 2011

Six impossible things

kw: book reviews, nonfiction, physics, cosmology

I almost put "fantasy" as a keyword, but we are in a realm that a great many physicists accept as fact. I just finished reading The Grand Design by Stephen Hawking and Leonard Mlodinow. I have enjoyed Dr. Hawking's prior books, and I enjoyed this one. However, it is clear he is preaching a viewpoint, and I came away unconvinced.

Stephen Hawking has been laboring for decades to produce an elegant theory that explains the Universe without any special conditions required. This is understandable. There are dozens of parameters that must be fine-tuned for the Standard Model and quantum theory to "work". For example, there is a resonance in the energy spectrum of the Carbon-12 nucleus; if it were a few percent higher or lower, either the triple alpha process would not work, leading to a helium universe, or the carbon could not further fuse to produce oxygen. Either way, no heavier elements would be produced and there would be no "rocky" planets.

In this book, a Theory of Everything is still an ideal, but the authors throw in the towel and propose instead M-Theory (the reason for "M" is not known). M-Theory is a hodge-podge of all the cosmological theories that work within a certain range of parameters, that also fit together in the ranges where they overlap. In numerical methods we call that a "piecewise continuous" construction, and it is usually a sorry substitute for a complete analytical method.

Last evening the local PBS station showed a double Nova feature: "The Fabric of the Cosmos: The Illusion of Time" and "The Elegant Universe: Einstein's Dream". They covered material similar to that found in The Grand Design, and at one point the narrator (scientist and author Brian Greene) raised the question, "Are we smart enough to understand a theory of everything if we see one?" He answered that most cosmologists believe that we are. I remain skeptical. The Universe already passed through 13.7 billion years without any creatures (that we know of) who understand that there are quanta; it could take a few thousands or millions of years of further evolution before we actually understand them.

At present the foundational quantum theory is the Copenhagen Interpretation. Its basic tenet states that a quantum event does not solidify into an actual quantum being at an actual location until an observation is made. The implication, at least as Niels Bohr understood it, was that such an observation needed to be made by an intelligent observer. Thus, the old saw, "If a tree falls in the forest, does it make a sound?" must be answered, "Of course, not; it doesn't even reach the ground if nobody is there to observe it." This is patent nonsense. Quantum events happen by the quintillions per cubic meter every second, whether anybody is looking or not.

Hawking and Mlodinow never mention the Copenhagen Interpretation, but it underlies several chapters. These illustrate just how desperately scientists avoid saying, "I don't know." For example, it is known that a particle, whether a boson (such as a photon) or fermion (such as an electron or even a molecule), that is moving with a certain velocity, is influenced by objects that it passes "near", and even by objects farther away. It is conjectured that every moving particle is affected by every other particle in the universe. The strength of these effects are very small for objects that are farther "to the side" than one or two deBroglie wavelengths of the particle. But, apparently, never zero, even over light years.

I wonder what kind of experiment we'd have to do to determine whether the effect of a "nearby" object on the flight of an electron is to be evaluated using relativistic or "simultaneous" (that is, classical) mathematics. Could the object be a high-intensity laser beam? Probably; then you could use picosecond switching of such a beam to see when it deflects an electron. Considering that speed-of-light signals move about 30 cm/nsec, this one will take some doing.

Back to the affected particle. We call the scattering of particles into a diverging beam, by their passage through a hole or past an edge, "diffraction". Richard Feynman developed QED (quantum electrodynamics) by proposing that the particle actually took all possible paths between its starting position and its final absorption at some point (perhaps on a screen), and its eventual location was affected by some statistical combination of all that infinity of possible paths. If you actually do the work to add up a great many of the most probable paths, you can make very, very accurate predictions about the statistical results of a large number of quantum events, though you can predict nothing at all about any single event, not even whether it will in actuality happen.

Does a moving particle really take every path before "deciding" on one of them? Someone who says anything other than "I don't know" is just broadcasting ignorance. The all-paths premise is a model, one possible way of deriving the mathematics needed to make statistical predictions. We will most likely develop other models, and it is quite likely that at least one of them will have simpler math than QED.

An alternate model, but one that doesn't allow for mathematical treatment, is the splitting universe. This idea proposes that whenever something affects a particle, the universe splits into as many alternate universes as are needed for every path to be followed, just that each universe gets a different path. Considering that quantum events happen by the quintillions per second per cubic meter, that's a lot of universes.

A different multiple universe theory is based on the fine tuning seen in this one. It is proposed that quantities such as the fine-structure constant or the mass of a neutron can have a range of values, and in different universes all possible values are produced. The only universes that persist are those that have appropriate values that allow such persistence, and of those, only a very small number can support an environment in which life is able to arise and produce cosmologists. This is the anthropic principle (the authors do some arm-waving and show that both the weak and strong anthropic principles, as currently known, are the same thing. Thus I mention only "the" anthropic principle). Simply stated, the universe is the way it is because it had to be so, or we would not be here. Well, yeah, but so what? It is a tautology.

Finally, there is string theory. This was the subject of the second PBS show also. Fortunately on that show there were a few scientists interviewed who asked the obvious question, "Of the great many string theories being proposed, does any one of them predict anything? Can any of them be tested?" The answer is No and No. They are more evidence of a total inability of scientists to admit, "I don't know," and mean it. The phrase I always hear or read regarding a string theory is "What if…".

Everybody is terminally impatient. I mean that literally. Nearly all cases of accidental death are because somebody (usually the dead person) was too impatient to take the time to do something the right way, whether drive to the store or climb a ladder or cross the street. Hundreds of thousands of iatrogenic (doctor caused) deaths result from impatience on the part of the physician, and sometimes of the (soon to die) patient. In this case, we have a situation similar to "artificial intelligence". The term is a moving target, and the "AI techniques" being touted in some software products are quite far from what I would call "intelligent." I get IT geeks mad when I claim that the quickest way to produce true intelligence is to raise your children well and educate them well. Twenty years to produce a probably intelligent young person, versus seventy years and counting, plus billions and billions of dollars spent programming and database-building, and yet there is not one robot that could survive an English 101 college course.

It is the same with cosmological theories. We have to be patient enough to wait a number of generations for a few people to finish their education and who are smart enough to get the insights needed for better theories. I say "a few people" because, unless there had been a community of very smart people around in 1905-1925, Einstein's theories would have got nowhere. Once he had the critical insights, others understood, and the two Relativity theories took over physics.

Some day, cosmologists will look back at the disparity between special relativity and quantum mechanics, and sigh, "If only they had known X!" But it'll take a while before X becomes not just evident, but even possible, for a human brain. With X in hand, M-Theory won't be needed, strings and multiverses and such will be passé, and nobody will mention Copenhagen any more. Until then, we hobble along with what we have.

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