Book Look: From Eternity to Here, by Sean Carroll: I'm fond of pointing out, rather flippantly, that experience has made it plain to me that I was not put on this Earth to get it. Primarily this applies to women, taxes, and Jersey Shore, but the older I get the more I realize that it's really a much wider phenomenon. I don't think I was made to truly understand much of anything (except perhaps the extent to which I don't understand anything -- that's pretty clear).
Reading From Eternity to Here I was cheered by the fact that professional cosmologists and theoretical physicists, certainly one highest IQ demographics extant, don't really understand much of anything either.
I suppose most of us have been exposed to many of the surrealities of contemporary physics. The simplest and most common is the fact that nothing can go faster than the speed of light. In common experience, this makes no sense. We have no evolutionary experience with there being an upper limit to speed that we couldn't imagine overcoming with technology and/or imagination. Open the door to quantum mechanics and things go from surreal to outright bizarre. Statistical existence where a cat is both dead and alive in some sense. Particles pop in and out of reality. None of this makes any sense -- quite literally. The experience we have of the world as provided by our senses cannot accommodate any of this. There is no way for us to picture it, other than through some very strained analogies. Carroll does better than most at describing a lot of this stuff; he brings fresh analogies and lucid descriptions to the nonsense.
But the high concept of this book is time. What is time? Where did time come from? Why does it only go in one direction? Is there a defined starting point? Does anybody really know what...(sorry).
Our sense of time is mostly a byproduct of memory. We recall previous events but have no knowledge of future ones (only surmises). Therefore, we feel as though we are moving through time from the written past to the unwritten future. Let me try my hand at an analogy of my own.
Picture an enormous, infinitely high, multi-story building. Each floor is the entire universe in one instant of time. You are born into existence on the 387,293,817,678,624,456,879th floor, or something. Also on that floor is your mother, the obstetrician, everyone in the hospital, cars and pedestrians throughout the city, every animal , vegetable, and mineral on earth, every planet in the solar system, every star in the galaxy, every galaxy in the universe -- all frozen at that specific instant. On the next floor up -- 387,293,817,678,624,456,880 -- you are there also, but the tiniest fraction of an instant later. Your lungs are starting to draw their first air, your mother has every so slightly started to smile, all the cars on the street have moved a tiny fraction of an inch, the planets have moved infinitesimally along in their orbits, the universe has expanded an eensy bit. Each subsequent floor higher is another slice in time further along in your life, and it continues further after you're gone.
You -- your conscious being, if you will -- move up through every floor and record some subset of the state of the universe. As a newborn you record pretty much nothing. Later on you gather more but still only a subset of the things that affect your senses. Upon recording it you move up to the next floor. The only information you carry from floor to floor is what you recorded. This is memory. You have no idea you are on a different floor, or even that there is a building. All there is is what you recorded from the previous floor(s) and what is there now. Lather, rinse, repeat for your whole life.
The only reason we have our concept of time is that you can only go up to the next floor. There is no down button on the elevator. The question that greatly bothers theoretical physicists is Why? What stops you from going back down? Pretty much everything else in the universe is reversible -- up/down, faster/slower, more/less. Not time.
If my reading of this is correct, the reason you can't go back is something called Entropy. We seem to have a law of the universe that states entropy must always increase. The real world image that is usually tossed out at this point is that you can't unscramble an egg. Carroll uses the image of a box separated by a partition into two sections with a small passageway between. Fill one side with gas, and eventually the gas will flow through the partition such that there is rough and even amount on either side. You would never observe a situation where both sides were filled and suddenly all the gas just darted over to one side. One side full is low Entropy, both filled is high Entropy. The world only works in one way, lower to higher.
Fair enough, but then Carroll starts poking holes in this idea. For example, there is nothing in the realm of physical laws that prevents the random motions of molecules on the gas to all just happen to move into one side of the box. It is just so extraordinarily unlikely that we call it "never." And there are more serious problems, such as the fact that while there is near uniform agreement among cosmologists that Entropy only gets higher, the early universe started with high entropy and then somehow got itself in a very low state around the time of the big bang. So it would seem that at some point early on traffic was running backwards on our low-to-high Entropy one way street.
At this point we encounter major wackness. That is not only because it gets harder and harder for a hopelessly Newtonian mind to picture the models described, but also because, as I mentioned, these guys aren't terribly sure of what they are talking about. To his credit, Carroll is quite clear on that, and emphasizes when he is on a topic that most cosmologists are in sync versus when he is wandering off the reservation versus when nobody has any clue.
Why does this get so hard to understand? Well, part of the reason is that physicists have a great deal of difficulty accepting that the universe just may be something special, something astronomically unlikely. We end up with weirder and weirder ideas just to make it look like our universe was likely (or at least not unlikely) by some standard. We have to make it into something that was expected to happen. So we end up with things like Dark Energy and Dark Matter and String Theory and Inflation, none of which have much of a corollary to common experience and little hope of experimental verification. It almost seems like when they run into a hole in their expectations, they just invent some concept that will plug it up, then give it a catchy name. The whole endeavor is the equivalent of some bankrupt gambler looking for a reason the roulette wheel landed on double zero. On the other hand, that's what a model is, isn't it? Something that fits expectations so you live with it until something proves it wrong or a more accurate model comes along. That's how science works.
I've spent more time on content than I should have. From a reader's perspective Carroll is the bee's knees when it comes to lucid explanations. His descriptions work especially well if you are already versed in the usually analogies drawn to describe these phenomena that you might get from a Discovery Channel documentary. He approaches them from a different angle, helping to reinforce ideas that are generally non-intuitive. For instance he starts with what existence is like now and identifies how it breaks down under scrutiny and the subsequent work done to repair it, whereas most narratives would start with the Big Bang and simply work forward chronologically. More importantly, he injects just the right amount of history and biography. His prose a clear, precise, and good humored. He's not lecturing so much as chatting with you over coffee.
Should you read From Eternity to Here? If you are interested in these topics, then certainly. It is a terrific popularization of cosmology; the best I've read, although my readings aren't remotely exhaustive. But don't take it lightly. There is a good deal of substance here and it will require brain-in-vice level abstract thinking for a mere mortal to really get a grip on it. Even then, you probably won't truly get it. Just like women, taxes, and Jersey Shore.
