The Cosmic Web: Mysterious Architecture of the Universe by J. Richard Gott (Princeton, 2016) 255 pages
After a sex book last time (Full Service), I don’t feel bad in plucking a physics (ok, astrophysics) book off the pile this time. I love books like this, and I just bought one that will make a good comparison to Gott’s ideas in a few weeks….so stay tuned. You can compare this book to Frank Wilczek’s A Beautiful Question as well, but considering the smallest things in the world instead of the largest.
Not too long ago, astronomers knew as much about the structure of the universe as anyone can tell from looking up at the sky. The Earth seems to be suspended in the middle of a big sphere of stars, with a few wandering things that turned out to be planets (Copernicus put them circling the sun instead of everything orbiting the earth). There was this big cloudy lane called the Milky Way through the sky, really thick in Sagittarius, and a few smaller cloudy blobs scattered here and there, again with a lot toward the south.
Once telescopes came along, Da Vinci saw that the Milky Way consisted of myriads of small stars, presumably dim because they were so very far away. So the universe grew a lot bigger a couple of hundred years ago. And it’s been growing ever since, as the initial chapters of Gott’s book points out.
Remember those cloudy blobs? Those are other “island universes” like the Milky Way. And it turned out that the sun wasn’t even in the center of the Milky Way, it’s sort of way out toward the rim, as determined by some of those blobs, which turned out to be globular clusters that formed a kind of halo around the center of our galaxy.
Why does any of this really matter? Well, in a sense it really doesn’t, except that the fact that humans can figure it out is very, very cool. But in the big scheme of things, sometimes I think only the geeks and nerds really care. It reminds me of an old joke I heard in college: the professor says “yes, science has determined that the sun will burn out in 4 billion years, ending all life on earth…” and a sleepy student in back goes “What! That’s horrible!” And the professor says “well, but 4 billion is a lot of years…” and the student says “Oh, that’s ok then…I thought you said 4 million years.” Now, why anyone would really worry about anything happening that far in the future when we don’t usually worry about what will happen in 10 years (Global warming? What global warming?) is of course the joke.
But I think that our knowledge of the structure of the universe at the largest scales, like our understanding of the universe at the smallest atomic scale, can help us to figure out how humans fit in. It’s an odd fact that we happen to be suspended about halfway between the smallest and largest things we know about. Maybe it’s our job, in some sense, to figure it all out. Or not.
Anyway, this book costs about thirty bucks (but you can find it cheaper), but it well worth it just to look at the 16 color plates that Gott has assembled to illustrate our knowledge of the universe as it stands today.
In a real sense, the purpose of Gott’s text is to get you to understand what you are looking at when you examine the incredible beauty of Plate 5, a yellow and bright gold group of filaments that shows how galaxies flow in the “Laniakea Supercluster.” And there we are, a little red dot, not to represent our planet or even our galaxy, but our whole group of galaxies. It’s a big universe out there. (Laniakea means “immeasurable heaven” in Hawaiian: we live in a place as beautiful as a tropical paradise.)
Gott was one of the first people to figure this large-scale structure out. The universe is a sponge it seems, with big bubbles or voids or more or less empty space and thin veils of galaxies forming the material of the sponge to keep it all from falling apart (kidding: it can’t really fall apart, andeverything is pretty isolated anyway.
Much of the central text describes the infighting between US scientists, who favored a model where the galaxies form walls and clusters in space, and the Russians, who favored a model where the galaxies form a honeycomb and the voids are the “clusters” in some sense. If this bores you, and it was tough going in places, just look at the pictures and read that pages that reference the color plates. Our home is a beautiful place.
The blurb on the jacket promises that Gott’s work on distant galaxies and surveys like the Sloan Digital Sky Survey will supply “vital clues” on both the origin of the universe and “the next trillion years” that stretch out ahead. So don’t worry about the universe going away anytime soon. Now, the sun, on the other hand…we’re doomed!
Addendum: Let me add a few words about the numbers million-billion-trillion because astronomers and politicians tend to throw those numbers around without any real appreciation of what it all means.
OK, I used to say when I taught this stuff, everyone wants to win a million dollars in the lottery. What if you could win a million dollars in a lottery every day of your life? How long would it take to win a billion dolloars? Well, a billion is a thousand million (and a million is a thousand thousand, of course). There are 365 days in a year, so it will take about 3 years to win a billion dollars (there’s no winner on Sunday if you want to make the numbers fit a bit better). Three years at a million dollars a day. How long for a trillion? Well, a thousand billion is a trillion, and at a million dollars a day it will take 3,000 years to win a trillion (the national debt of the USA is about 19 trillion dollars, by the way).
When I used to teach this, given Bill Gates of Microsoft’s age and net worth at the time, it turned out he was making a million dollars a day since the day he was born.
So the next time you see anyone use the terms million-billion-trillion as if they were somehow the same type of thing as a dollar bill and a ten and a hundred, take a minute to make sure they understand just how much that is, and how big the universe is.