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January 31 - March 15, 2020
After nine billion years of such enrichment, in an undistinguished part of the universe (the outskirts of the Virgo Supercluster) in an undistinguished galaxy (the Milky Way) in an undistinguished region (the Orion Arm), an undistinguished star (the Sun) was born.
What we do know, and what we can assert without further hesitation, is that the universe had a beginning.
Ordinary matter is what we are all made of. It has gravity and interacts with light. Dark matter is a mysterious substance that has gravity but does not interact with light in any known way.
Gravity, the most familiar of nature’s forces, offers us simultaneously the best and the least understood phenomena in nature.
Dark matter and nuclear fusion don’t mix. Thus, as best we can figure, the dark matter doesn’t simply consist of matter that happens to be dark. Instead, it’s something else altogether. Dark matter exerts gravity according to the same rules that ordinary matter follows, but it does little else that might allow us to detect
“Matter tells space how to curve; space tells matter how to move.”
How else could we believe that sodium is a poisonous, reactive metal that you can cut with a butter knife, while pure chlorine is a smelly, deadly gas, yet when added together they make sodium chloride, a harmless, biologically essential compound better known as table salt? Or how about hydrogen and oxygen? One is an explosive gas, and the other promotes violent combustion, yet the two combined make liquid water, which puts out fires.
Every second of every day, 4.5 billion tons of fast-moving hydrogen nuclei are turned into energy as they slam together to make helium within the fifteen-million-degree core of the Sun.
To picture a pulsar, imagine the mass of the Sun packed into a ball the size of Manhattan. If that’s hard to do, then maybe it’s easier if you imagine stuffing about a billion elephants into a Chapstick casing.
orbit. A simple calculation reveals that most of them will hit Earth within a hundred million years. The ones larger than about a kilometer across will collide with enough energy to destabilize Earth’s ecosystem and put most of Earth’s land species at risk of extinction. That would be bad.
(An artist coworker of mine once asked whether alien life forms from Europa would be called Europeans. The absence of any other plausible answer forced me to say yes.)
more bacteria live and work in one centimeter of my colon than the number of people who have ever existed in the world. That kind of information makes you think twice about who—or what—is actually in charge.
Imagine a life-form whose brainpower is to ours as ours is to a chimpanzee’s. To such a species, our highest mental achievements would be trivial.
Every cup that passes through a single person and eventually rejoins the world’s water supply holds enough molecules to mix 1,500 of them into every other cup of water in the world. No way around it: some of the water you just drank passed through the kidneys of Socrates, Genghis Khan, and Joan of Arc.
A single breathful draws in more air molecules than there are breathfuls of air in Earth’s entire atmosphere. That means some of the air you just breathed passed through the lungs of Napoleon, Beethoven, Lincoln, and Billy the Kid.
We do not simply live in this universe. The universe lives within us.
