25 August 2016

BOOK REPORT: A Brief History of Time by Stephen Hawking

Imagine there’s this ant. Tiny little ant.

No, an ant isn’t small enough. Imagine something smaller. An egyptian mite. Super tiny. Have you seen those things? They’re right at the edge of my visual range. Like pixels but in real life.

Imagine this teenie-tiny little mite weighs so much that his bulk makes him sink right into the earth. And then all the earth’s matter starts to collapse inward on top of him into the hole he’s creating.

And imagine this mite radiates energy, so much energy that he’s white hot, like he’d melt your face off. Or he’s as hot as a nuclear explosion that happened three feet away from you. Or as hot as the sun, which is a whole collection of nuclear bombs in one.

Now imagine this mite is so dense that when light particles attempted to bounce off his red exoskeleton (which is what photons do to just about everything) the light gets sucked in by so much gravity that it never comes back out, turning this guy perceptibly invisible. Sayonara light.

These mites do exist. There’s one at the center of our galaxy. (It’s called a black hole, even though it’s white hot.) Only I under-exaggerated all of his characteristics. He’s actually much heavier, much, much hotter, and much, much, much smaller.

That’s a lot of mite packed into such a small space.

* * *

I wrote that bit above, but it’s based on principles I learned from A Brief History of Time (or re-learned, since this isn’t my first Hawking rodeo). Incidentally, I read A Briefer History of Time directly after, not realizing that it’s basically a second edition of the original book, with a few things updated here and there. But this book is heavy enough that two readings back-to-back is actually a good way to do it. If you only read one, I recommend the Briefer version. 

Hawking was born exactly 300 years to the day after the death of Galileo. That’s one fun fact, which Hawking sprinkles throughout his cosmic narrative—like his being late for free plane ride because of rain. His personal voice makes the science a lot more fun. (And my master’s thesis, Look Your Reader in the Eye, which has a fantastic title, is about that very topic.)

Just three more tidbits and I’ll leave you be.

First, did you know that the substance of our universe is mostly matter and energy that’s completely transparent and unobservable? It’s called dark matter and dark energy. Check this out:

Second, take a look at this drawing of a street. You’re in the car in the middle. Do you agree that the relative speed of the bus above is 30 mph and the relative speed of the bus below is 90 mph? Well, guess what. Light doesn’t follow this rule. If we transformed the two buses into bolts of light, and if your car in the middle were a pretty fast spaceship, the relative speeds of both beams of light would be equal to each other (both would be exactly the speed of light). It’s a mind-bending paradox.

Third and last, in quantum mechanics there’s something called the “uncertainty principle.” It means that quantum particles have a fundamental unpredictability about them. And this isn’t just about how they can’t be observed carefully. It’s their very nature to be unpredictable. I think that’s super cool. The opposite of unpredictability is determinism, meaning every reaction always has an explainable cause. Determinism suggests that you can predict everything based on simple actions and reactions. But the uncertainty principle says that there’s more to life than just reacting in direct response to what acts on you. Instead, you, like the quantum particle, can make choices and go in unpredictable directions based on your will rather than on predictive causes.

This is one of my favorite books.

If you love science, you should check it out

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— J