If only one thing were enough

 kw: book reviews, nonfiction, science, explanations, interdisciplinary

For Marcus Chown, explaining things isn't just a "man thing," it's a lifelong passion. He bites off a very big chunk to chew, to explain 21 science ideas most people find hard to comprehend, in The One Thing You Need to Know: The Simple Way to Understand the Most Important Ideas in Science. Dr. Chown seems to be used to juggling a passel of sciences.

The best I can do with a book this comprehensive is to limn a sampling:

• The Second Law of Thermodynamics – For the sake of background, the First Law of Thermodynamics is Conservation of Energy, or in cosmological terms, Conservation of Mass-Energy. The Second Law can be stated a few ways: "Work requires a flow of energy" and "Entropy must always increase" are two easy ones. Implied in these two statements is the prefixed caveat that "In a closed system…" Thus, building a house decreases entropy (a measure of disorder), but it does so only locally. In total, there is a great increase in overall entropy. Think of a huge pile of sawdust and other wastes… For you or I to grow from a fertilized egg cell into a baby, then to an adult, decreases entropy within our body, but increases entropy even more in the Universe as a whole. There's a curious statement on p61: "…the energy of a photon is proportional to its temperature…" The author is making the case that for each photon the Earth receives from the Sun, it emits 200 photons of lower energy. Photons don't really have a temperature, but in a thermal regime, it takes a hot object to emit photons of higher energy, so the statement is useful shorthand. The "average" photon from the Sun conveys a greenish color to our eyes and has a wavelength near 550 nm, and an energy of about 4.4 eV (look up electron-Volts). Of course, the Sun emits photons with a very wide range of wavelengths and thus energies. The average temperature of the Earth is 15°C (59°F), so it radiates infrared photons into space with and "average" wavelength of about 10,000 nm or 10 µ, and an energy of 0.124 eV. The ratio 4.4/0.124 = 35.5. That's rather different from 200, but it would take a much more elaborate analysis to produce a more definitive value, and that's not what this book (or this review) is all about.
• Atoms – This is a simpler concept, as long as we stay with pre-quantum-mechanical explanations. The word "atom" comes from the Greek word atomos, meaning "un-cuttable" or "indivisible". The philosopher Democritus 2,400 years ago asked, "If I cut this piece of pottery in half, and then do it again, and again…could I go on forever?" He declared, "No." But there was no way to prove it. Now we have abundant proof and demonstrations, including a microscope called AFM, for "atomic force microscope", that can produce an image, magnified several million times, of the atoms on a surface. X-ray methods allow us to visualize the arrangement of atoms in a crystal. But they are not longer "un-cuttable". When I was a physics student, "atom smashers" of a few types, including a synchrotron at my college, routinely banged ions against one another, "splitting" atoms into smaller pieces. Now, we think that electrons and quarks are the truly un-cuttable entities. Probably, but stay tuned…
• The Standard Model – I got out of physics because I was a college senior during the heyday of the "particle zoo", when the number of "-ons" and "resonances" and other items showering out of atom smashers had grown to a list of 100 or more. A few years later physicists proposed the "Eightfold Way", which was tweaked and modified and added to, until now we can make this diagram:

Ordinary matter is entirely composed of the leftmost column of 4 "leptons" and the 5 "bosons". There is a caution, though: all the leptons have anti-matter "twins", such as the positron, which is the anti-electron. The gluon, photon, Z, and higgs have no anti-bosons, or one can say they are each their own antiparticle. The W has an anti-W.

Thus, the particle zoo is smaller now, with "only" 30 "fundamental" particles, rather than a hundred or so.

This is a great synthesis, but it is still incomplete. We don't know if gravity is quantized, or what to do with a "graviton" if such a critter exists. I presume it would be a boson.

The introduction to this chapter (#15) includes the quote, "People want to know about what's going on with what's in the universe, what are particles like, what are the basic rules of nature. There's a lot of curiosity out there." by Sheldon Lee Glashow. I'd say, for "people" he really meant "scientists" or even "cosmologists." For the rest of the human race, the curiosity is mainly directed to "What's my next meal?" and "Where can I sleep safely?" and "Can I get laid tonight?"

• Quantum Computers – The hype about these is like entropy; it is ever-increasing. And so we find it here. One useful point is made, and this must be the "one thing" for this chapter: Quantum mechanical math only applies to an isolated thing, whether an electron, an atom, a buckyball, or anything else, in a very low-temperature vacuum chamber (i.e., isolated from the Universe; I guess gravity doesn't count). Constructs larger than single particles need to maintain "coherence," such as that seen in Bose-Einstein condensates. Anything at all from the outside that interacts with the "thing" will cause it to "decohere" and enter a fixed state that is described by classical mechanics, not quantum mechanics. That "anything at all" includes photons with extremely low energies, which is why Bose-Einstein condensates can only be created in an extremely rarefied vacuum at a temperature less than one degree above absolute zero. Apparently, thermal photons emitted by the walls of a chamber at such a low temperature are either too sparse to disrupt the condensate, or too low in energy to do so. Anyway, the math of quantum multiplicity shows that adding a single qubit to an array of qubits doubles the number of final states it can use, thus doubling the complexity of the problems it can solve. The trouble is, a quantum computer can only produce a single output, so it is best suited to doing something like cracking a single password. Like second-grade math teachers, for a quantum computer there is "only one right answer". I guess matrix math is out of reach. If you know how passwords are cracked with current equipment, you know that they cannot be tackled one at a time; a hacker typically gathers the "hashes" from thousands to millions of passwords and cross-matches them against a "universal hash generator". If a hacker can extract a few or a few hundred passwords that way, he can make a ton of money exploiting just those, and the uncracked ones can be left for a later, more rigorous attempt. I really haven't seen another problem that quantum computers are suited for, and the author doesn't suggest any either. But along the way he makes a wonderful statement about the current state of science: "Something physicists never like to admit is that they have only ever solved one problem exactly: the two-body problem." That's the orbit of two objects about one another under the force of gravity only. He is right! Everything else is approximated. Science has some distance yet to go.
• The Big Bang – If you begin with the current state of the Universe, and the observation that all the galaxies are separating from one another at a rate that varies primarily with their distance, you can "extrapolate to zero" and wind the Universe back to the initial state of zero volume and infinite temperature that "must" have begun everything. This was determined before 1930. More detailed observations and analyses since then have found three "hangups":
1. The background "temperature" is too uniform; it should express more of the initial turmoil unless there was time for the temperature to equalize. It is posited that a slightly slower start, during the first trillionth of a trillionth of a trillionth of a second, was followed by a very brief period of enormous expansion, dubbed Inflation, for about a billionth of a trillionth of a trillionth of a second, at which time the Universe was the size of a softball, and then continued expanding at a more "sedate" rate comparable to what we see today. This is kind of like blowing up a weather balloon with C-4.
2. The gravity of all visible matter is too small for galaxies to have formed in the calculated time (13.8 billion years) since time-zero, and the gravity of all visible matter in a galaxy is too small to hold the stars in their measurable orbits. It is posited that the actual mass of gravitating "stuff" is about seven times as great as what we can see; the extra "stuff" is called Dark Matter. So far, we can only know it from its gravity.
3. Observations of distant Type 1a supernovae seem anomalous; calculations based on their brightness indicate that universal expansion is speeding up. It is posited that a kind of negative gravity extracted from "vacuum energy", dubbed Dark Energy, is responsible. I personally think that we don't yet know enough about how Type 1a supernovae behaved in the first billion years or so, when the "metals" content (everything except hydrogen and helium) of the Universe was very, very small.

The author concludes this chapter (#21) by saying, "…there is a strong suspicion that there is a deeper, more fundamental cosmological theory to be found, which will merge inflation, dark matter and dark energy into a more appealing, seamless entity." I would think that a proper theory would make all three superfluous. Time will tell

It's a very enjoyable book. I'd have preferred each chapter to begin with an introductory blurb, stating "the concept to be grasped" and "the one thing that'll help you grasp it". I don't really see any "one thing" in any of the chapters. But it's cool anyway.