Monday, August 26, 2013

Selected quotes from "A Universe from Nothing"

A dense book on modern cosmology. A passionate defense of science against the simplistic ideas of theology/religion. A short summary of some of the most important things we've learnt about the universe in the last century. "A Universe from Nothing" is all that and more. I read a review somewhere (on Amazon?) that basically said the afterword by Richard Dawkins was pointless, but I actually liked it. It was a welcome summary, as this book tackles a lot of difficult concepts. Recommended.

Here are my (raw) Kindle highlights:
  • "The fact that we need to refine what we mean by “common sense” in order to accommodate our understanding of nature is, to me, one of the most remarkable and liberating aspects of science." 
  • "Reality liberates us from the biases and misconceptions that have arisen because our intellects evolved through our animal ancestors, whose survival was based on whether predators might lurk behind trees or in caves and not on understanding the wave function of electrons in atoms."
  • "Our modern conception of the universe is so foreign to what even scientists generally believed a mere century ago that it is a tribute to the power of the scientific method and the creativity and persistence of humans who want to understand it."
  • "Nevertheless, the declaration of a First Cause still leaves open the question, “Who created the creator?” After all, what is the difference between arguing in favor of an eternally existing creator versus an eternally existing universe without one?"
  • "The universe is the way it is, whether we like it or not. The existence or nonexistence of a creator is independent of our desires. A world without God or purpose may seem harsh or pointless, but that alone doesn’t require God to actually exist."
  • "Surely, invoking “God” to avoid difficult questions of “how” is merely intellectually lazy."
  • "Science has been effective at furthering our understanding of nature because the scientific ethos is based on three key principles: (1) follow the evidence wherever it leads; (2) if one has a theory, one needs to be willing to try to prove it wrong as much as one tries to prove that it is right; (3) the ultimate arbiter of truth is experiment, not the comfort one derives from one’s a priori beliefs, nor the beauty or elegance one ascribes to one’s theoretical models."
  • "Hubble’s law: There is a linear relationship between recessional velocity and galaxy distance. Namely, galaxies that are ever more distant are moving away from us with faster velocities!"
  • "One of the most poetic facts I know about the universe is that essentially every atom in your body was once inside a star that exploded. Moreover, the atoms in your left hand probably came from a different star than did those in your right. We are all, literally, star children, and our bodies made of stardust."
  • "This is one of the most famous, significant, and successful predictions telling us the Big Bang really happened. Only a hot Big Bang can produce the observed abundance of light elements and maintain consistency with the current observed expansion of the universe."
  • "Over the course of the history of our galaxy, about 200 million stars have exploded. These myriad stars sacrificed themselves, if you wish, so that one day you could be born. I suppose that qualifies them as much as anything else for the role of saviors."
  • "The job of physics is not to invent things we cannot see to explain things we can see, but to figure out how to see what we cannot see—to see what was previously invisible, the known unknowns."
  • "In fact, you may be old enough have seen its effects without realizing it, if you remember the days before cable television, when channels used to end their broadcast days in the wee morning hours and not run infomercials all night. When they went off the air, after showing a test pattern, the screen would revert to static. About 1 percent of that static you saw on the television screen was radiation left over from the Big Bang."
  • "By nothing, I do not mean nothing, but rather nothing—in this case, the nothingness we normally call empty space. That is to say, if I take a region of space and get rid of everything within it—dust, gas, people, and even the radiation passing through, namely absolutely everything within that region—if the remaining empty space weighs something, then that would correspond to the existence of a cosmological term such as Einstein invented."
  • "For any fourth grader will tell you how much energy is contained in nothing, even if they don’t know what energy is. The answer must be nothing. Alas, most fourth graders have not taken quantum mechanics, nor have they studied relativity."
  • "Dirac was vindicated, but he also recognized his earlier lack of confidence in his own theory by later saying that his equation was smarter than he was!"
  • "This is so remarkable I want to stress it again. Quantum fluctuations, which otherwise would have been completely invisible, get frozen by inflation and emerge afterward as density fluctuations that produce everything we can see! If we are all stardust, as I have written, it is also true, if inflation happened, that we all, literally, emerged from quantum nothingness."
  • "In one sense it is both remarkable and exciting to find ourselves in a universe dominated by nothing. The structures we can see, like stars and galaxies, were all created by quantum fluctuations from nothing."
  • "This means that, the longer we wait, the less we will be able to see. Galaxies that we can now see will one day in the future be receding away from us at faster-than-light speed, which means that they will become invisible to us. The light they emit will not be able to make progress against the expansion of space, and it will never again reach us. These galaxies will have disappeared from our horizon."
  • "Indeed, in a strange coincidence, we are living in the only era in the history of the universe when the presence of the dark energy permeating empty space is likely to be detectable. It is true that this era is several hundred billion years long, but in an eternally expanding universe it represents the mere blink of a cosmic eye."
  • "It is worth repeating the implications of this remarkable agreement more forcefully: Only in the first seconds of a hot Big Bang, with an initial abundance of protons and neutrons that would result in something very close to the observed density of matter in visible galaxies today, and a density of radiation that would leave a remnant that would correspond precisely to the observed intensity of the cosmic microwave background radiation today, would nuclear reactions occur that could produce precisely the abundance of light elements, hydrogen and deuterium, helium and lithium, that we infer to have comprised the basic building blocks of the stars that now fill the night sky."
  • "Physics is, after all, an empirical science, driven by experiment and observation. Had we not observationally inferred the existence of dark energy, I doubt any theorist would have been bold enough to suggest its existence today."
  • "We can consider ourselves lucky that we live at the present time. Or as Bob and I put it in one of the articles we wrote: “We live at a very special time . . . the only time when we can observationally verify that we live at a very special time!”"
  • "Regardless, the fundamental problem illustrated by the possible future end of cosmology is that we have only one universe to test—the one we live in."
  • "Before proceeding, however, it is perhaps worth ending with another, more literary picture of the likely future I have presented here and one that is particularly relevant to the subject of this book. It comes from Christopher Hitchens’s response to the scenario I have just described. As he put it, “For those who find it remarkable that we live in a universe of Something, just wait. Nothingness is heading on a collision course right toward us!”"
  • "We are hardwired to think that everything that happens to us is significant and meaningful. We have a dream that a friend is going to break her arm, and the next day we find out that she sprained her ankle. Wow! Cosmic! Clairvoyant?"
  • "By forgetting that most of the time nothing of note occurs during the day, we then misread the nature of probability when something unusual does occur: among any sufficiently large number of events, something unusual is bound to happen just by accident."
  • "Put another way, it is not too surprising to find that we live in a universe in which we can live!"
  • "Maybe all of the mysteries of particle theory can be solved by invoking the same mantra: if the universe were any other way, we could not live in it."
  • "We have discovered that 99 percent of the universe is actually invisible to us, comprising dark matter that is most likely some new form of elementary particle, and even more dark energy, whose origin remains a complete mystery at the present time."
  • "A truly open mind means forcing our imaginations to conform to the evidence of reality, and not vice versa, whether or not we like the implications."
  • "At the same time, in science we have to be particularly cautious about “why” questions. When we ask, “Why?” we usually mean “How?”"
  • "“Why” implicitly suggests purpose, and when we try to understand the solar system in scientific terms, we do not generally ascribe purpose to it."
  • "This is what differentiates them from purely theological questions, which generally presume the answers up front. Indeed, I have challenged several theologians to provide evidence contradicting the premise that theology has made no contribution to knowledge in the past five hundred years at least, since the dawn of science. So far no one has provided a counterexample. The most I have ever gotten back was the query, “What do you mean by knowledge?” From an epistemological perspective this may be a thorny issue, but I maintain that, if there were a better alternative, someone would have presented it. Had I presented the same challenge to biologists, or psychologists, or historians, or astronomers, none of them would have been so flummoxed."
  • "I remind you of the unique facet of a flat universe, at least on scales where it is dominated by matter in the form of galaxies, and where a Newtonian approximation remains valid: in a flat universe, and only in a flat universe, the average Newtonian gravitational energy of every object participating in the expansion is precisely zero."
  • "This results in the second amazing implication of inflation, that small-density fluctuations in empty space due to the rules of quantum mechanics will later be responsible for all the structure we observe in the universe today. So we, and everything we see, result out of quantum fluctuations in what is essentially nothingness near the beginning of time, namely during the inflationary expansion."
  • "But no one ever said that the universe is guided by what we, in our petty myopic corners of space and time, might have originally thought was sensible."
  • "This is the beauty of science, and it should not be threatening. Science simply forces us to revise what is sensible to accommodate the universe, rather than vice versa."
  • "To summarize then: the observation that the universe is flat and that the local Newtonian gravitational energy is essentially zero today is strongly suggestive that our universe arose though a process like that of inflation, a process whereby the energy of empty space (nothing) gets converted into the energy of something, during a time when the universe is driven closer and closer to being essentially exactly flat on all observable scales."
  • "Empty space is complicated. It is a boiling brew of virtual particles that pop in and out of existence in a time so short we cannot see them directly."
  • "Now few biochemists and molecular biologists doubt that life can arise naturally from nonlife, even though the specifics are yet to be discovered."
  • "Feynman’s methods focus on the key fact to which I alluded at the beginning of this chapter: quantum mechanical systems explore all possible trajectories, even those that are classically forbidden, as they evolve in time."
  • "But this seems an arbitrary semantic distinction designed by those who have decided in advance (as theologians are wont to do) that the supernatural (i.e., God) must exist so they define their philosophical ideas (once again completely divorced from any empirical basis) to exclude anything but the possibility of a god."
  • "In a multiverse of any of the types that have been discussed, there could be an infinite number of regions, potentially infinitely big or infinitesimally small, in which there is simply “nothing,” and there could be regions where there is “something.” In this case, the response to why there is something rather than nothing becomes almost trite: there is something simply because if there were nothing, we wouldn’t find ourselves living there!"
  • "I recognize the frustration inherent in such a trivial response to what has seemed such a profound question throughout the ages. But science has told us that anything profound or trivial can be dramatically different from what we might suppose at first glance."
  • "The universe is far stranger and far richer—more wondrously strange—than our meager human imaginations can anticipate. Modern cosmology has driven us to consider ideas that could not even have been formulated a century ago."
  • "This is why philosophy and theology are ultimately incapable of addressing by themselves the truly fundamental questions that perplex us about our existence. Until we open our eyes and let nature call the shots, we are bound to wallow in myopia."
  • "Alternatively, if the matter that makes us up was created at the beginning of time by some quantum processes, as I have described, we are virtually guaranteed that it, too, will disappear once again. Physics is a two-way street, and beginnings and endings are linked. Far, far into the future, protons and neutrons will decay, matter will disappear, and the universe will approach a state of maximum simplicity and symmetry."
  • "I have always been attracted to the myth of Sisyphus and have likened the scientific effort at times to his eternal task of pushing a boulder up a mountain, only to have it fall back each time before he reaches the top. As Camus imagined, Sisyphus was smiling, and so should we. Our journey, whatever the outcome, provides its own reward."
  • "In this sense, science, as physicist Steven Weinberg has emphasized, does not make it impossible to believe in God, but rather makes it possible to not believe in God. Without science, everything is a miracle. With science, there remains the possibility that nothing is. Religious belief in this case becomes less and less necessary, and also less and less relevant."
  • "The choice to turn to the notion of divine creation falls to each of us, of course, and I don’t expect the ongoing debate to die down anytime soon. But as I have stressed, I believe that if we are to be intellectually honest, we must make an informed choice, informed by fact, not by revelation."
  • "I find oddly satisfying the possibility that, in either scenario, even a seemingly omnipotent God would have no freedom in the creation of our universe. No doubt because it further suggests that God is unnecessary—or at best redundant."
  • "Theologians may speculate about angels on pinheads or whatever is the current equivalent. Physicists might seem to have their own angels and their own pinheads: quanta and quarks, “charm,” “strangeness,” and “spin.” But physicists can count their angels and can get it right to the nearest angel in a total of 10 billion: not an angel more, not an angel less. Science may be weird and incomprehensible—more weird and less comprehensible than any theology—but science works. It gets results. It can fly you to Saturn, slingshotting you around Venus and Jupiter on the way. We may not understand quantum theory (heaven knows, I don’t), but a theory that predicts the real world to ten decimal places cannot in any straightforward sense be wrong. Theology not only lacks decimal places: it lacks even the smallest hint of a connection with the real world."

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