Death From the Skies! by Phillip Plait

Source of book: Borrowed from the library

I first discovered Phil Plait from his own astronomy blog, Bad Astronomy. It is a great place to get stunning celestial photos, and other astronomy related updates.

This site happened to mesh well with our science study this year, which was astronomy. As I noted in an earlier post, I chose to take the kids to the Bryce Canyon National Park astronomy festival this year to wrap up our course. Prior to that, during a camping trip to Pinnacles National Park, we ran into a family from northern California who were seriously into astronomy, and possessed both a telescope and (in the case of the mother), an outstanding knowledge of the sky. That was our first chance to view nebulae and galaxies through a telescope. We later met them out in the desert for clearer skies and a view of Saturn. Bryce was just another chance (and bigger telescopes) to explore the universe. It is amazing how it worked out for us.

I decided to bring this book along on our astronomy related trip because, well, why not? In another coincidence, we ended up attending a ranger lecture on some of the same topics. So it all tied together. 

The title and the cover art are intentionally provocative - and tongue in cheek. Plait is a not primarily a media figure, but an actual professional physicist and astronomer. He got his start working on the analysis team for the Hubble Telescope, and went on to other interstellar research, before being tabbed by NASA for public outreach due to his writing and speaking skills. Even understanding his area of research takes a decent background in astronomy.

Thus, the title is really a dig at the way the media loves a crisis and bold, ludicrous headlines; but rarely if ever stops to learn about and understand the underlying facts. Like the title, the book is filled with delightfully dry humor, and parody of the hyperbole used in news stories.

This book discusses the threats to human existence from space. This ranges from the common, but survivable (and potentially avoidable) scenario of a large meteor or small asteroid to the inevitable and catastrophic, but extremely distant fact of the death of the universe. In between are such “fun” possibilities as a neighboring star going supernova, and a small black hole passing through the earth.

In order to explain these potentialities, Plait engages in a surprisingly detailed explanation of stars and their life cycles, the birth of stars, the formation of solar systems, the ways that different stars die, the interaction of gravity, and so on. If you want a quick education on all of this and more, this is actually a pretty good book to start with. Pop Science may not be a substitute for a full mathematical education, but for those of us who wish to know without making a career of it, books like this are enlightening - and fun.

In what should come as absolutely no surprise, I found Plait’s dry sense of humor to be delightful. Just one example from the second chapter, which discusses solar flares and coronal mass ejections, is a good start. (If you have no idea what a coronal mass ejection is, get this book!) Crucial to understanding these events is a knowledge of the sun’s magnetic field. (Since the sun has little iron, how does this occur? Another reason to get the book.)

When taken all together, the Sun more closely resembles a ball of writhing worms than a single sphere of gas. It’s like a street map of Tokyo, but in three dimensions and changing with time as well. Because of this, the magnetic field of the Sun is a nightmare as well, making it ferociously difficult to understand. On the positive side, though, it also keeps a lot of solar physicists off the streets.

There are too many fun facts to mention many of them, so I will limit myself to a few.

The first one is an epiphany regarding black holes. We tend to think of black holes as being huge, with enormous event horizons. Get even a few light years away, and you are a goner.

Not so. First was the obvious: a black hole with a mass of, say 5 solar masses, exerts the same gravity as 5 suns at the same distance. (Plenty of stars in our neighborhood are close to 5 solar masses. These will eventually go supernova and become a black hole.) So a planet could easily enough orbit around one without falling in.

In fact, five solar masses, give or take, is the most common size of black hole, resulting from the death of a star.

How big is such a black hole? And what is the diameter of its event horizon?

18 miles. That’s all.

I guess this should have been obvious. In order to get matter dense enough, it would have to fit in a really small space.

Even supermassive black holes, like the one at the center of the Milky Way, aren’t really that “big” in terms of size. Mass, yes, as in millions of times the mass of our sun. Size, not so much. The event horizon wouldn’t even reach to the orbit of the earth around our sun. Even the biggest detected anywhere, hundreds of billions of solar masses, would still have an event horizon merely a couple times as big as the size of our solar system. Two light hours across.

Considering that the nearest star to our own is 4 light years away, even the largest event horizon is chump change compared to the actual distances out there. Crazy stuff.

See why I liked this book?

One more tidbit. At one time, the universe was believed to be infinite in both dimension and time. In other words, the stars continued on forever in all directions, and the universe had always existed. If this were true, then the sky would be equally bright in all dimensions. Which it isn’t.

Oddly, it was, of all people, Edgar Allan Poe who first solved the conundrum. Poe posited that the universe must be finite in one (or both) dimensions. Either you run out of stars as you get far enough away (the universe is finite in dimension), or the universe was formed recently enough that the light from the most distant stars hasn’t had a chance to reach us yet.

The research that showed that the universe was expanding came decades later, and led to the conclusion that the universe had a definite beginning (14 billion years, give or take), and that it is also finite in extent.

One final bit, which may be a preview of a future post.

Plait is publicly opposed to a few ideas that he views as counter to science and dangerous in effect.

The first is the anti-vaccination movement. I could spend a whole post on this, but suffice it to say that the entire movement is founded on one fraudulent study by a certain Andrew Wakefield, who concocted a scheme along with an unethical trial attorney to win huge settlements from vaccine manufacturers while selling chelation treatments. This information came to light years after the study, and it has since been withdrawn. This information is easy to find from reputable sources on the internet, as is the fact that no study that had controls, a reasonable sample size, and the bare minimums of proper conduct has ever shown a correlation (let alone causation) between vaccines and autism.

And yet the myth persists.

Obviously, I agree wholeheartedly with Plait on this one.

Plait also rails against global warming denialists. I don’t feel like touching this one right now, so I will avoid it completely.

The final one is Plait’s opposition to Young Earth Creationism.

This really needs to be a future blog post. I’ll just give a teaser by saying that I am solidly Old Earth. I have looked deep into the heavens, and even with a small scope, it is pretty dang obvious that the deeper you look, the more you see. With the Hubble, it is possible to see many billions of light years away (and therefore into the past.) The YEC “explanations” for this are insulting to anyone who has a working high school level of knowledge in math and science. One textbook we used even tried to claim that the speed of light (despite ALL evidence to the contrary) must have been different in the past. Not using that publisher ever again.

Places like Bryce have on display evidence of the age of the earth (geology) and of the universe (astronomy). The more I read YEC “explanations” for what I see, the more I am convinced that they are making stuff up to fit a hyper-literalist view of the creation account. There are just too many contradictions necessary to support a 6000 year old universe. 

One further point that Plait makes, which I believe is important, is that within the scope of what it can explain (what, how, where, and when, but not the ultimate why), science leads to an ever-increasing knowledge of the truth. It isn’t always right, but it gets more right with time, experimentation, and further data. As Plait puts it, science asymptotically approaches reality, although it is hard to know exactly how far up the curve we are at this time.

YEC, on the other hand, sits at one place, which it believes to be the truth, despite all evidence to the contrary. The core of the belief is a hyper-literalist approach to a few passages from an ancient document, written before even ancient Greek science, and hardly intended as a science textbook.

As I said, fodder for a future post.

I should also note that, unlike certain prominent atheists (ahem, Richard Dawkins), Plait makes a distinction between religion in general and old earth creationism (and its relative theistic evolution) and young earth creationism. Plait is, in general, not anti-religion, but against those who wish to ignore those things that science can show (the how, not necessarily the ultimate why).

Anyway, perfect timing for this book. I recommend it for fans of science, and for anyone who loves to learn. It is fascinating stuff.

Note on other books and posts:

For more on the question of the ultimate “why?” I recommend Why Does the World Exist? by Jim Holt.

For some provocative information on genetics and mutation, The Violinist’s Thumb by Sam Kean is a great read.