A Short History of Nearly Everything

by Bill Bryson

What is extraordinary from our point of view is how well it turned out for us. If the universe had formed just a tiny bit differently—if gravity were fractionally stronger or weaker, if the expansion had proceeded just a little more slowly or swiftly—then there might never have been stable elements to make you and me and the ground we stand on. Had gravity been a trifle stronger, the universe itself might have collapsed like a badly erected tent, without precisely the right values to give it the right dimensions and density and component parts. Had it been weaker, however, nothing would have coalesced. The universe would have remained forever a dull, scattered void.

For example, for the universe to exist as it does requires that hydrogen be converted to helium in a precise but comparatively stately manner—specifically, in a way that converts seven one-thousandths of its mass to energy. Lower that value very slightly—from 0.007 percent to 0.006 percent, say—and no transformation could take place: the universe would consist of hydrogen and nothing else. Raise the value very slightly—to 0.008 percent—and bonding would be so wildly prolific that the hydrogen would long since have been exhausted.

However—and here’s the thing—people on the train would have no sense of these distortions. To them, everything on the train would seem quite normal. It would be we on the platform who looked weirdly compressed and slowed down. It is all to do, you see, with your position relative to the moving object. This effect actually happens every time you move. Fly across the United States, and you will step from the plane a quinzillionth of a second, or something, younger than those you left behind. Even in walking across the room you will very slightly alter your own experience of time and space. It has been calculated that a baseball thrown at a hundred miles an hour will pick up 0.000000000002 grams of mass on its way to home plate. So the effects of relativity are real and have been measured. The problem is that such changes are much too small to make the tiniest detectable difference to us. But for other things in the universe—light, gravity, the universe itself—these are matters of consequence.

The upshot of all this is that we live in a universe whose age we can’t quite compute, surrounded by stars whose distances we don’t altogether know, filled with matter we can’t identify, operating in conformance with physical laws whose properties we don’t truly understand.

The Moon’s steady gravitational influence keeps the Earth spinning at the right speed and angle to provide the sort of stability necessary for the long and successful development of life.

sodium, one of the most unstable of all elements, and chlorine, one of the most toxic. Drop a small lump of pure sodium into ordinary water and it will explode with enough force to kill. Chlorine is even more notoriously hazardous. Though useful in small concentrations for killing microorganisms (it’s chlorine you smell in bleach), in larger volumes it is lethal. Chlorine was the element of choice for many of the poison gases of the First World War. And, as many a sore-eyed swimmer will attest, even in exceedingly dilute form the human body doesn’t appreciate it. Yet put these two nasty elements together and what do you get? Sodium chloride—common table salt.