13 Things That Don't Make Sense Read Online Free Page A

distance from Earth, you find that the
     farther away a galaxy is, the faster it is moving. If one receding galaxy is twice as far from Earth as another, it will be
     moving twice as fast. If it is three times more distant, its speed is three times greater. To Hubble, there was only one possible
     explanation. The galaxies were like paper dots stuck onto a balloon; blow it up, and the dots don’t grow, but they do move
     apart. The very space in between the galaxies was growing. Hubble had discovered that the universe is expanding.
    It was a heady time. With this expansion, the idea of a big bang, first suggested in the 1920s, bubbled to the surface of
     cosmology. If the universe was expanding, it must once have been smaller and denser; astronomers began to wonder if this was
     the state in which the cosmos had begun. Vesto Slipher’s work had led to the first evidence of our ultimate origins. The same
     evidence would eventually bring us the revelation that most of our universe is a mystery.
    TO understand how we know a significant chunk of the cosmos is missing, tie a weight to a long piece of string. Let the string
     out, and swing the weight around in a circle. At the end of a long string, the weight moves pretty slowly—you can watch it
     without getting dizzy. Now pull the string in, so the weight is doing tiny orbits of your head. To keep it spinning around
     in the air, rather than falling down and strangling you, you have to keep it moving much faster—so fast you can hardly see
     it.
    The same principle is at work in the motions of the planets. The Earth, in its position close to the Sun, moves much faster
     in its orbit than Neptune, which is farther out. The reason is simple: it’s about balancing forces. The gravitational pull
     of the Sun is stronger at Earth’s radial distance out from the Sun than at Neptune’s. Something with Earth’s mass has to be
     moving relatively fast to maintain its orbit. For Neptune to hold its orbit, with less pull from the distant Sun, it goes
     slower to keep in equilibrium. If it moved at the same speed as Earth, it would fly off and out of our solar system.
    Any orbiting system ought to follow this rule: balancing a gravitational pull and the centrifugal forces means that, the farther
     something is from whatever is holding it in orbit, the slower it will move. And, in 1933, that is exactly what a Swiss astronomer
     called Fritz Zwicky didn’t see.
    As construction began on the Golden Gate Bridge and a forty-three-year-old Adolf Hitler was appointed chancellor of Germany,
     Zwicky noticed something odd about the Coma cluster of galaxies. Roughly speaking, stars emit a certain amount of light per
     kilo, so, looking at the amount of light coming out of the Coma cluster, Zwicky could estimate how much stuff it contained.
     Zwicky’s problem was that the stars on the edges of the galaxies were moving far too fast to be constrained by the gravitational
     pull of that amount of material. According to his calculations, the only explanation was that there was about four hundred
     times more mass in the Coma cluster than could be accounted for by the cluster’s visible matter.
    It should have been enough to launch the dark matter hunt, but it wasn’t—for the worst of scientific reasons. Comb the Internet
     for references to Zwicky, and you’ll find brilliant next to maverick , genius next to insufferable . Like Slipher, he doesn’t figure large in the astronomy textbooks, despite his many important discoveries. He was the first
     to see that galaxies form clusters. He coined the term supernova . He was certainly one of a kind. He built a ski ramp next to the Mount Wilson Observatory in the San Gabriel Mountains of
     California, for example; in the winter Zwicky would haul his skis to work so he could keep his ski-jumping skills honed. But
     it was his interpersonal skills that needed most attention. He was a prickly, difficult man, convinced of his own genius,
     and