Origins: Fourteen Billion Years of Cosmic Evolution Read Free Page A

the 15-million-degree cores of stars. And at every extreme imaginable we find the outrageously hot and dense conditions that prevailed during the first few moments of the universe. To understand what happens in each of these scenarios requires laws of physics discovered after 1900, during what physicists now call the modern era, to distinguish it from the classical era that includes all previous physics.
    One major feature of classical physics is that events and laws and predictions actually make sense when you stop and think about them. They were all discovered and tested in ordinary laboratories in ordinary buildings. The laws of gravity and motion, of electricity and magnetism, and of the nature and behavior of heat energy are still taught in high school physics classes. These revelations about the natural world fueled the industrial revolution, itself transforming culture and society in ways unimagined by generations that came before, and remain central to what happens, and why, in the world of everyday experience.
    By contrast, nothing makes sense in modern physics because everything happens in regimes that lie far beyond those to which our human senses respond. This is a good thing. We may happily report that our daily lives remain wholly devoid of extreme physics. On a normal morning, you get out of bed, wander around the house, eat something, then dash out the front door. At day’s end your loved ones fully expect you to look no different than you did when you left, and to return home in one piece. But imagine yourself arriving at the office, walking into an overheated conference room for an important 10 A.M. meeting, and suddenly losing all your electrons—or worse yet, having every atom of your body fly apart. That would be bad. Suppose instead that you’re sitting in your office trying to get some work done by the light of your 75-watt desk lamp, when somebody flicks on 500 watts of overhead lights, causing your body to bounce randomly from wall to wall until you’re jack-in-the-boxed out the window. Or what if you go to a sumo wrestling match after work, only to see the two nearly spherical gentlemen collide, disappear, and then spontaneously become two beams of light that leave the room in opposite directions? Or suppose that on your way home, you take a road less traveled, and a darkened building sucks you in feet first, stretching your body head to toe while squeezing you shoulder to shoulder as you get extruded through a hole, never to be seen or heard from again.
    If those scenes played themselves out in our daily lives, we would find modern physics far less bizarre; our knowledge of the foundations of relativity and quantum mechanics would flow naturally from our life experiences; and our loved ones would probably never let us go to work. But back in the early minutes of the universe that kind of stuff happened all the time. To envision it, and to understand it, we have no choice but to establish a new form of common sense, an altered intuition about how matter behaves, and how physical laws describe its behavior, at extremes of temperature, density, and pressure.
    We must enter the world of E = mc 2 .
    Albert Einstein first published a version of this famous equation in 1905, the year in which his seminal research paper entitled “Zur Elektrodynamik bewegter Körper” appeared in Annalen der Physik , the preeminent German journal of physics. The paper’s title in English reads “On the Electrodynamics of Moving Bodies,” but the work is far better known as Einstein’s special theory of relativity, which introduced concepts that forever changed our notions of space and time. Just twenty-six years old in 1905, working as a patent examiner in Bern, Switzerland, Einstein offered further details, including his best-known equation in another, remarkably short (two-and-a-half-page) paper published later the same year in the same journal: “Ist die Trägheit eines Körpers von seinem Energieinhalt