Stepstones to infinity

 kw: book reviews, nonfiction, science, astronomy, space science, popular treatments

My favorite astrophysicist, Neil deGrasse Tyson, published a new book last year in collaboration with Lindsey Nyx Walker, in the Startalk series: To Infinity and Beyond: A Journey of Cosmic Discovery. With apologies to Buzz Lightyear, the title makes it clear this is no scientific treatise.

As one might expect, the book is fun to read, pitched at just the right level for a popular audience, and copiously illustrated. Rather than chapters, the book has four sections, with a subtitle every couple of pages. The sections are titled "Leaving Earth", "Touring the Sun's Backyard", "Into Outer Space", and "To Infinity and Beyond". Broadly speaking, the sections are like layers of an onion, starting at the center.

The second section, on the planets and their satellites and asteroids and other denizens of the solar system, is the longest, as befits the greater knowledge we have "in the Sun's back yard", where at least we have sent instruments to pass by or even orbit the planets and selected objects. The book went to press before the capsule of material returned from Asteroid Bennu was opened, so that's not mentioned. What is mentioned is the quest to colonize Mars, which cannot realistically be done without terraforming it. Engineering solutions, including carpet bombing the polar ice caps with nuclear weapons, have been proposed. Dr. Tyson has this to say:

"In any case, if humanity ever develops enough geoengineering know-how to terraform Mars as our escape plan after we trash Earth, then we should certainly be able to use that intelligence to make Earth livable again and save ourselves from requiring a planet B in the first place." (p. 135)

To which I add a strong, "Amen!"

The fourth section, after treating what we know of the distant cosmos in a general way, gets a bit philosophical. The authors have this to say about "beyond", that is, about the many-worlds interpretation of quantum uncertainty: "The many-worlds solution may not be simple, but it is the simplest explanation for the oddities at quantum scales." I must contend with that:

Consider sunlight shining through an ordinary window. When the light encounters the glass, ~4% is reflected from the outer surface and ~96% passes into the glass. Then about another 4% is reflected from the second surface and the rest, ~92%, continues onward. Interestingly, the light that reflected back into the glass pane is partly reflected and then most passes through. Some smaller and smaller fraction of the original light bounces back and forth inside the glass pane. Glass is not 100% transparent, to soon whatever has not escaped is absorbed. Considering only visible light, sunlight has an intensity of around 500 watts per square meter, or 0.05 watt (50 mw) per square centimeter. Skipping the math, the number of photons of visible light that encounter the glass each second is about 1.4x10¹⁷, or 140 quadrillion (140 million billion). Each photon "decides" whether to reflect or pass through, twice because the glass has two surfaces. According to the many-worlds interpretation, 280 quadrillion entire universes are created every second, because of sunlight shining through one square centimeter of glass. I have a picture window in my family room that has an area of two square meters. On a sunny morning, every second, about 5.6x10²¹ universes spring into existence, along what dimensions we have know way to discern. Five and a half sextillion. Every second.

Folks, that's just silly. Whatever photons and other quanta are, they are doing something we fundamentally don't understand, and interpretations such as many-worlds reveal how immensely far we are from achieving such understanding.

We are like the pilgrim in this famous engraving from an 1888 book by Flammarion, trying to see beyond our own horizon. Our imagination falls short. Newton imagined himself as a beach comber being fascinated by this shell or that pretty pebble, being ignorant of the expanse of the ocean that tossed them up.

All that aside, and aside from a few errata I'll get into shortly, the book is as entertaining as it is comprehensive. I strongly recommend it.

---------------------------

I have to bring out a few matters where the authors, or a copy editor, ought to have known better:

1. On p. 22, about warming by infrared light, "…once they absorb the various wavelengths of radiation, molecules on Earth's surface are transformed into infrared and are reemitted by the ground." This is a rather dramatic blunder. The molecules are not transformed into infrared! The relevant phrase should read, "…molecules on Earth's surface emit infrared radiation." All the wavelengths of sunlight that reach the ground warm its substance, and it then emits some of this energy as infrared.
2. On p. 119, about the slowing of Earth's rotation, mostly by its interaction with the Moon, it is stated, "After two centuries, days are four milliseconds faster." In this context, the word "faster" is misused. The days are "four milliseconds longer." Gah!
3. On p. 131, "Today, Mars is a frigid tundra." The word "tundra" implies a cold landscape with cold-resistant plant cover. There are no plants on Mars. I don't know what word to use, but the word "tundra" is wrong.
4. On p. 206, on relationships between the intrinsic brightness of stars and their apparent brightness because of their varying distances, "Sirius, the brightest star in our night sky, is smaller than Earth and 8.6 light-years away,…" Siriusly?!?!? As it happens, Sirius is 1.7 times the size of the Sun. Its companion, the white dwarf designated Sirius B, which is much too faint to see without a large telescope, is indeed smaller than Earth.
5. Finally, look carefully at this illustration of a prism producing a spectrum:

This is found on p. 212, where spectroscopy is being discussed. The illustration is from Getty Images. The way the beam of light bends upward as it enters the prism implies that the prism has a refractive index less than 1, which is impossible. Such a material would require the light to go "faster than light" within it.

Compare with this illustration:

This is from Britannica online. It is more correct, showing the light entering being refracted toward the perpendicular to the glass surface as it passes into the prism, and then refracted away from the perpendicular of the second glass surface as it exits. P.S. I was a spectroscopist for a few years…

This illustration isn't totally accurate, however. The best spectroscopic glass disperses the spectrum by a little less than one degree. The spectrum at the right is being dispersed about 15°. However, this bit of scientific license is needed to make the principle more clear.

I put the query "prism spectrum" into a Google Images search. I found that a great many repositories of stock photos have it wrong; only about one-third have it right! Don't Getty and all the others have anyone with scientific understanding on their staffs?