Article — From the December 2011 issue

The Accidental Universe

Science’s crisis of faith

( 4 of 6 )

The most striking example of fine-tuning, and one that practically demands the multiverse to explain it, is the unexpected detection of what scientists call dark energy. Little more than a decade ago, using robotic telescopes in Arizona, Chile, Hawaii, and outer space that can comb through nearly a million galaxies a night, astronomers discovered that the expansion of the universe is accelerating. As mentioned previously, it has been known since the late 1920s that the universe is expanding; it’s a central feature of the Big Bang model. Orthodox cosmological thought held that the expansion is slowing down. After all, gravity is an attractive force; it pulls masses closer together. So it was quite a surprise in 1998 when two teams of astronomers announced that some unknown force appears to be jamming its foot down on the cosmic accelerator pedal. The expansion is speeding up. Galaxies are flying away from each other as if repelled by antigravity. Says Robert Kirshner, one of the team members who made the discovery: “This is not your father’s universe.” (In October, members of both teams were awarded the Nobel Prize in Physics.)

Physicists have named the energy associated with this cosmological force dark energy. No one knows what it is. Not only invisible, dark energy apparently hides out in empty space. Yet, based on our observations of the accelerating rate of expansion, dark energy constitutes a whopping three quarters of the total energy of the universe. It is the invisible elephant in the room of science.

The amount of dark energy, or more precisely the amount of dark energy in every cubic centimeter of space, has been calculated to be about one hundred-millionth (10–8) of an erg per cubic centimeter. (For comparison, a penny dropped from waist-high hits the floor with an energy of about three hundred thousand—that is, 3 × 105—ergs.) This may not seem like much, but it adds up in the vast volumes of outer space. Astronomers were able to determine this number by measuring the rate of expansion of the universe at different epochs—if the universe is accelerating, then its rate of expansion was slower in the past. From the amount of acceleration, astronomers can calculate the amount of dark energy in the universe.

Theoretical physicists have several hypotheses about the identity of dark energy. It may be the energy of ghostly subatomic particles that can briefly appear out of nothing before self­annihilating and slipping back into the vacuum. According to quantum physics, empty space is a pandemonium of subatomic particles rushing about and then vanishing before they can be seen. Dark energy may also be associated with an as-yet-unobserved force field called the Higgs field, which is sometimes invoked to explain why certain kinds of matter have mass. (Theoretical physicists ponder things that other people do not.) And in the models proposed by string theory, dark energy may be associated with the way in which extra dimensions of space—beyond the usual length, width, and breadth—get compressed down to sizes much smaller than atoms, so that we do not notice them.

These various hypotheses give a fantastically large range for the theoretically possible amounts of dark energy in a universe, from something like 10115 ergs per cubic centimeter to –10115 ergs per cubic centimeter. (A negative value for dark energy would mean that it acts to decelerate the universe, in contrast to what is observed.) Thus, in absolute magnitude, the amount of dark energy actually present in our universe is either very, very small or very, very large compared with what it could be. This fact alone is surprising. If the theoretically possible positive values for dark energy were marked out on a ruler stretching from here to the sun, with zero at one end of the ruler and 10115 ergs per cubic centimeter at the other end, the value of dark energy actually found in our universe (10–8 ergs per cubic centimeter) would be closer to the zero end than the width of an atom.

On one thing most physicists agree: If the amount of dark energy in our universe were only a little bit different than what it actually is, then life could never have emerged. A little more and the universe would accelerate so rapidly that the matter in the young cosmos could never pull itself together to form stars and thence form the complex atoms made in stars. And, going into negative values of dark energy, a little less and the universe would decelerate so rapidly that it would recollapse before there was time to form even the simplest atoms.

Here we have a clear example of fine-tuning: out of all the possible amounts of dark energy that our universe might have, the actual amount lies in the tiny sliver of the range that allows life. There is little argument on this point. It does not depend on assumptions about whether we need liquid water for life or oxygen or particular biochemistries. As before, one is compelled to ask the question: Why does such fine-tuning occur? And the answer many physicists now believe: The multiverse. A vast number of universes may exist, with many different values of the amount of dark energy. Our particular universe is one of the universes with a small value, permitting the emergence of life. We are here, so our universe must be such a universe. We are an accident. From the cosmic lottery hat containing zillions of universes, we happened to draw a universe that allowed life. But then again, if we had not drawn such a ticket, we would not be here to ponder the odds.

is a physicist and novelist who teaches at MIT. His novel <em>Mr g: A Novel About the Creation</em> was published in January 2012 by Pantheon.

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  • WintersGale

    I find it interesting even as art follows the societal philosophy of a generation (or at times generations), what this author is articulating is that science is doing the same. Currently we are in the philosophical age of post-modernism (many think we are beginning to move out and into another phase philosophy). Post-modernism postulates there is no truth, that truth is subjective to the individual. If there is no truth then it follows there are no absolutes. (No absolutes is a self-defeating logic since the statement is itself an absolute.) The author unwittingly has told us that science is following the premise established in post-modernist thought. You’ll find that artist do the same, take a look at modern art and see how they have painted,… “there are not absolutes.”

  • Boris D.

    There is no “scientific” reason to be an atheist. As the evolutionary theory continues to fall apart, and our technology allows us to see that the “fine-tuning” on earth is too complex to be a mere accident, atheistic explantions become more and more ridiculous.
    They used to say it was extra-terestrials, but that begs the question, “Who created them?”
    Now this?? An infinite number of universes, of which there can never be any proof? Puh-leeze.
    Is the idea of a God that abhorrent to them that they grasping at these straws?
    Scientists scoff at the belief in a creator because of the blind faith it requires. They label people who believe in the Divine as toothless, ignorant Bible thumpers. Now their “theory” requires just as much, nay MORE, faith.

    P.S. Eat that, Bill Nye :)~

    • Jose Hawkins

      For me, a God, gods or no god and whether or not there is an after life isn’t abhorrent, but rather the nature of religion, especially the judeo/christan interpretation. For some reason, people love to compare apples and oranges as if they are the same. No, I’m fine with the existence of God, gods or no god so long as we treat each other, all life and this planet decently.

  • slorimer

    Near the beginning the author says;

    The underlying hope and belief of this enterprise has always been that these basic principles are so restrictive that only one, self-consistent universe is possible

    And later;

    Many of the fish, the theorists, hope to prove that the entire cosmos necessarily has to be filled with water.

    I wonder if these hopes are attributed by the author. It would seem hubristic and contrary to the idea of science to have a preferred answer in mind before we inquire. I imagine a scientist would be more excited to find something that contradicts what they expect than something that supports a preconceived idea.

    As Douglas Adams said;

    There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.

  • Terry A Davis

    secrecies shrink transgression father eased stuff Please
    rescue infants rise troublesome mortified direction fabric
    CONSEQUENTIAL heavier rockstar Language god wittingly
    vote A deemed drive mould tookest Death bared weigh winding
    drowsiness partners returned supplied supporting govemed
    influences Carthaginian corrupt Wills tcosa10

  • Bg_Rdish

    Physics, even in its theoretical variety, has heretofore been a science. Armchair theorists can conceive a multitude of different ‘worlds’, but empiricism is still the ultimate arbiter between competing theoretical constructs. Now, if I understand the author correctly, he’s reporting that theoretical physicists are currently positing theories that don’t adhere to the traditional notion of causation and are immune to empirical falsification. If that’s the case, then theoretical physicists are no longer working in the realm of empirical science. They’ve transitioned from Platonism with respect to merely physical laws to full-fledged philosophy.

  • Hugh Beaumont

    We’re told that we are here by chance,
    There was no morning glory,
    But give me endless time and space,
    And I’ll pitch any story.

  • Rickard

    Thank you for the fair and even-handed representation of religious people and ID thinkers, it is really comforting. If more people took this fair approach (on both sides), maybe we could all get along much better and stop treating each other like dirt. This article has made me very happy.

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