Astrophysics for People in a Hurry by Neil deGrasse Tyson

★★★☆☆ (3/5)

A selection of my favourite passages from the book

Points to Contemplate

  • The universe is under no obligation to make sense to you.—NDT
  • The laws of physics prescribing the formation of these spectral signatures on the Sun were the same laws operating on Earth, ninety-three million miles away.
  • Science thrives not only on the universality of physical laws but also on the existence and persistence of physical constants.
  • In Germany before World War II, laboratory-based physics far outranked theoretical physics in the minds of most Aryan scientists. Jewish physicists were all relegated to the lowly theorists’ sandbox and left to fend for themselves.
  • Invoking the military edict “trust but verify,” the U.S. deployed a new series of satellites, the Velas, to scan for gamma ray bursts that would result from Soviet nuclear tests. The satellites indeed found bursts of gamma rays, almost daily. But Russia wasn’t to blame. These came from deep space—and were later shown to be the calling card of intermittent, distant, titanic stellar explosions across the universe, signaling the birth of gamma ray astrophysics, a new branch of study in my field.
  • These findings tell us it’s conceivable that life began on Mars and later seeded life on Earth, a process known as panspermia. So all Earthlings might—just might—be descendants of Martians.
  • The day our knowledge of the cosmos ceases to expand, we risk regressing to the childish view that the universe figuratively and literally revolves around us. In that bleak world, arms-bearing, resource-hungry people and nations would be prone to act on their “low contracted prejudices.” And that would be the last gasp of human enlightenment—until the rise of a visionary new culture that could once again embrace, rather than fear, the cosmic perspective.

Fascinating Stellar Space

  • One of the most distant (known) objects in the universe is not a quasar but an ordinary galaxy, whose feeble light has been magnified significantly by the action of an intervening gravitational lens. We may henceforth need to rely upon these “intergalactic” telescopes to peer where (and when) ordinary telescopes cannot reach, and thus reveal the future holders of the cosmic distance record.
  • If omega is less than one, the actual mass-energy falls below the critical value, and the universe expands forever in every direction for all of time, taking on the shape of a saddle, in which initially parallel lines diverge. If omega equals one, the universe expands forever, but only barely so. In that case the shape is flat, preserving all the geometric rules we learned in high school about parallel lines. If omega exceeds one, parallel lines converge, and the universe curves back on itself, ultimately recollapsing into the fireball whence it came.
  • There is no distance where the force of gravity reaches zero.
  • And if a planet is teeming with flora and fauna, its atmosphere will be rich with biomarkers—spectral evidence of life. Whether biogenic (produced by any or all life-forms), anthropogenic (produced by the widespread species Homo sapiens), or technogenic (produced only by technology), such rampant evidence will be hard to conceal.

Scientific Nuggets

  • If all mass has gravity, does all gravity have mass? We don’t know.
  • Einstein’s general theory of relativity, put forth in 1916, gives us our modern understanding of gravity, in which the presence of matter and energy curves the fabric of space and time surrounding it.
  • Later still, the electroweak force split into the electromagnetic and the “weak nuclear” forces, laying bare the four distinct forces we have come to know and love: with the weak force controlling radioactive decay, the strong force binding the atomic nucleus, the electromagnetic force binding molecules, and gravity binding bulk matter.
  • And you’ll never catch a quark all by itself; it will always be clutching other quarks nearby. In fact, the force that keeps two (or more) of them together actually grows stronger the more you separate them—as if they were attached by some sort of subnuclear rubber band. Separate the quarks enough, the rubber band snaps and the stored energy summons E = mc2 to create a new quark at each end, leaving you back where you started.
  • Today, we’ve settled on the moniker “dark matter,” which makes no assertion that anything is missing, yet nonetheless implies that some new kind of matter must exist, waiting to be discovered.
  • “Matter tells space how to curve; space tells matter how to move.”
  • This means something quite simple: if you split iron atoms via fission, they will absorb energy. And if you combine iron atoms via fusion, they will also absorb energy.
  • The planet Jupiter, with its mighty gravitational field, bats out of harm’s way many comets that would otherwise wreak havoc on the inner solar system. Jupiter acts as a gravitational shield for Earth, a burly big brother, allowing long (hundred-million-year) stretches of relative peace and quiet on Earth. Without Jupiter’s protection, complex life would have a hard time becoming interestingly complex, always living at risk of extinction from a devastating impact.

Absolutism – the very phenomenon which Scientists oft rage against

  • after the laws of physics, everything else is opinion.
  • The cosmic perspective comes from the frontiers of science, yet it is not solely the provenance of the scientist. It belongs to everyone. The cosmic perspective is humble. The cosmic perspective is spiritual—even redemptive—but not religious. The cosmic perspective enables us to grasp, in the same thought, the large and the small. The cosmic perspective opens our minds to extraordinary ideas but does not leave them so open that our brains spill out, making us susceptible to believing anything we’re told. The cosmic perspective opens our eyes to the universe, not as a benevolent cradle designed to nurture life but as a cold, lonely, hazardous place, forcing us to reassess the value of all humans to one another. The cosmic perspective shows Earth to be a mote. But it’s a precious mote and, for the moment, it’s the only home we have. The cosmic perspective finds beauty in the images of planets, moons, stars, and nebulae, but also celebrates the laws of physics that shape them. The cosmic perspective enables us to see beyond our circumstances, allowing us to transcend the primal search for food, shelter, and a mate. The cosmic perspective reminds us that in space, where there is no air, a flag will not wave—an indication that perhaps flag-waving and space exploration do not mix. The cosmic perspective not only embraces our genetic kinship with all life on Earth but also values our chemical kinship with any yet-to-be discovered life in the universe, as well as our atomic kinship with the universe itself.

Beautifully Constructed Sentences

  • But in the beginning, during the Planck era, the large was small, and we suspect there must have been a kind of shotgun wedding between the two. Alas, the vows exchanged during that ceremony continue to elude us, and so no (known) laws of physics describe with any confidence the behavior of the universe over that time.
  • What we know is that the matter we have come to love in the universe—the stuff of stars, planets, and life—is only a light frosting on the cosmic cake, modest buoys afloat in a vast cosmic ocean of something that looks like nothing.
  • Not only is the solar system scarred by the flotsam of its formation, but nearby interplanetary space also contains rocks of all sizes that were jettisoned from Mars, the Moon, and Earth by the ground’s recoil from high-speed impacts.
  • Jupiter’s moon Europa has enough H2O that its heating mechanism—the same one at work on Io—has melted the subsurface ice, leaving a warmed ocean below. If ever there was a next-best place to look for life, it’s here. (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.)
  • When I track the orbits of asteroids, comets, and planets, each one a pirouetting dancer in a cosmic ballet, choreographed by the forces of gravity, sometimes I forget that too many people act in wanton disregard for the delicate interplay of Earth’s atmosphere, oceans, and land, with consequences that our children and our children’s children will witness and pay for with their health and well-being.

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