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Friday, October 3, 2008

Did Our Universe Have a Beginning?

FROM ROBERT LAWRENCE KUHN, HOST AND CREATOR OF CLOSER TO TRUTH: Everything in the universe has a beginning, but did the universe itself come with a start date? Does a “cosmic commencement” make sense?
“Did our universe have a beginning?” seems to be an easy question to pose and, with recent cosmological data, possible to answer. Not necessarily. The question has only three meaning-carrying words (the other three are grammatical facilitators), and these words—“our,” “universe,” and “beginning”—are all deeply ambiguous. Each can have multiple referents or expose alternative perspectives.
“Our”: Could there be other beings from whose frame of space-time or frame of mind the question would differ radically from ours?
“Universe”: What’s a universe? One of Alan Guth’s “pocket universes” generated by continuous inflation or one of Andrei Linde’s “balloon universes” generated by eternal chaotic inflation? Or does “universe” mean “all there is” (“all-that-is” in Arthur Peacock’s formulation), encompassing literally everything?
“Beginning”: What’s a beginning? Some kind of kick-starting, local event in our observable, light-cone universe? By direct evidence, that’s the most, it seems, we could ever know about, and even then only under the most optimistic of conditions. Well, that kind of a “beginning” would be interesting and certainly important, but not ultimately satisfying, at least not for me.
Pardon my epistemological greediness, but “satisfying” to me would only be some kind of ultimate, absolute, universally exhaustive answer. I’m not all that sure that such an answer would even be logically meaningful, much less ever approachable, but nonetheless, for whatever maladaption, that’s my minimum hurdle of satisfaction.
Creation is humanity’s ancient and perpetual fascination. In the past, when the “beginning” question was raised, there was no ambiguity because, no matter who you were or what your orientation, there were only two possible kinds of answers from which to select: something from nothing, or always existing.
In cosmology, it was the big bang versus steady state.
In religion, it was the Judeo-Christian creation of the world versus the Hindu-Eastern repetitions of endless cycles. Some in the Judeo-Christian tradition put more stock in God as sustainer, creating the world, as it were, all the time, irrespective of whether human-perceived clocks could ever have registered an actual beginning. Thus, the affirmative creative act of the Judeo-Christian God may bring the universe into being by a creation from nothing (creatio ex nihilo) or it may be a continuing creative sustaining of the universe (creation continua), or both.
Today, the cosmology is more complicated than big bang versus steady state. Several theories generate an endless sequence of cosmic epochs, each of which begins with some kind of a “bang” and ends with some kind of a “crunch.” In the Paul Steinhardt-Neil Turok “ekpyrotic” model, cycles of accelerated expansions are followed by contractions that produce the homogeneity, flatness, and energy needed to begin the next cycle (with each cycle lasting perhaps a trillion years). These physicists theorize that the cosmos was never compacted into a singularity but that what we call the big bang resulted from a collision of sorts between our entire three-dimensional existence and another such entity within higher-dimension space.
Mathematician and physicist Roger Penrose postulates a succession of universes prior to our own by envisioning some kind of mathematical-geometric space-time identity between the remote future of one universe and the big bang of the next (“conformal cyclic cosmology” is his terminology). He calls his suggestion “outrageous.”
But all this is theory. What’s the data?
Wendy Freedman and her team at the Carnegie Observatories took the better part of a decade with the Hubble Space Telescope to calibrate the Hubble constant, which measures the rate of the universe's expansion. Though there are complications, of course, to a first approximation, it seems one can run the movie of the universe’s expansion in reverse and calculate a beginning (now set at 13.7 billion years ago).
Is it that simple? Does a tight Hubble constant “prove” that the universe did, in fact, have a beginning? What impresses me are the multiple tests and independent measurements, all of which converge on a similar origin and age of the universe. Most meaningful is the cosmic background radiation, that “afterglow” of the heat of the big bang, which fills the sky in all directions and which shows the steady state universe to be false. Experimental astrophysicist George Smoot won the Nobel Prize for these measurements; he calls the pictorial representations “an ultrasound of the embryo universe”—galaxies and clusters of galaxies germinating from quantum fluctuations, seeds smaller than protons.
So it seems that our universe did have a beginning. We call it the “big bang,” but technically, under the most widely accepted cosmological model—inflation—the big bang was not the beginning. It emerged from the cauldron of cosmic inflation, when something infinitesimally small expanded majestically in an astonishingly brief instant, cooking up space, time, energy, and matter in a colossal cosmic stew.
The fundamental question is this: No matter the theory, was there ever a “something from nothing” start? In Guth’s inflation, no matter how high the number of universes that exist at any moment, inflation had to start with a beginning. Cosmic inflation may engender infinite universes forever into the future, but it cannot do so forever into the past. Under inflationary theory, there must be a finite number of universes in the past. Time’s arrow is not symmetrical. So unless something like the Steinhardt-Turok model of cyclical universes is correct, inflation demands that the universe had a beginning and that it had to start with some stuff, however small.
But where did this early stuff, no matter how small, come from?
Theology may posit an answer, but science, it would seem, cannot. Physicist Alexander Vilenkin disagrees; he claims to have an answer. He postulates that the laws of quantum mechanics can have the universe originating spontaneously, “quantum tunneling” out of the “quantum foam.” This is not absurd because the laws of quantum physics require particles to be popping in and out of existence.
But Vilenkin still has those pesky “laws of physics” with which to deal. From where did the laws of quantum mechanics come?
So, did our universe have a beginning? Three little questions: When? How? Why?
When: Well, 13.7 billion years ago. Cosmologists seem to have nailed the date with remarkable precision, a magnificent tribute to human ingenuity.
How? What caused it all?: Perhaps quantum fluctuations. Perhaps some prior state. However it happened, the laws of physics made it happen.
And we come quickly to why: Why did our universe begin? Why the laws of physics? Sometimes only silence … gets us closer to truth.

Robert Lawrence Kuhn speaks with Wendy Freedman, Alan Guth, George Smoot, Alexander Vilenkin, Paul Steinhardt, and Martin Rees in "Did Our Universe Have a Beginning?" the fourth episode in the Closer to Truth: Cosmos, Consciousness, God TV series, which airs Thursdays on the PBS HD network and many other PBS stations. (Also check out Kuhn’s piece for Skeptic magazine called “Why This Universe: Toward a Taxonomy of Possible Explanations.”) Every Friday, participants in the series will share their views on the previous day's episode.


Anonymous said...

The whole universe which is matter/energy was created by God in a dimentional state of nothingness called: Time

hgheinzmann said...

Are you saying that Time existed before matter/energy? How many dimensions does this dimentional (sic) state of nothingness have?