Alpha and Omega
Interview with Charles Seife : Part I
Astrobiology magazine had the opportunity to discuss 'how the universe began and how it will end' with Science magazine writer, Charles Seife. Seife is the author of a new book, Alpha and Omega, which describes how cosmologists today are trying to answer these age-old questions. Seife previously has written on the mathematical and cultural genesis of the number 'zero'. His latest adventures in cosmology bring a characteristic enthusiasm for a remarkable field undergoing a revolution.
One feature of this new cosmology is how powerful experiments and observations have combined to make what previously could only be speculated upon, into a set of testable hypotheses. For example, NASA's recent measurements of the universe's most 'ancient light' has revealed one of the earliest glimpses into how 'it' all might have begun.
Called WMAP (Wilkinson Microwave Anisotropy Probe) and the earlier Cosmic Background Explorer (COBE), the experiments measure the microwave noise that still hisses from the first 400,000 years after the big bang, when a charged gas or plasma first recombined to form neutral matter. Astronomers are looking back in time at the remnants of events 13.8 billion years ago. This event can be compared to a lifting of the fog, when an opaque cloud suddenly becoming transparent, and instruments like these can probe this ancient wall of fire and light.
While these measurements are known to many scientists, Seife has told their engaging stories in a way that captures the imagination of even those unfamiliar with the physics and math. For instance, the first attempts to uncover this microwave background dated back to 1965, when eventual Nobel winners at Bell Labs thought this ancient light had a more mundane cause: their New Jersey antenna had attracted a flock of pigeons, which at first were thought to be contributing a thin layer of 'noise' onto their sensitive microwave instruments.
Alpha and Omega asks the questions: how did the universe begin and how will it end? And how do we know?
|Omega, the last letter of the Greek alphabet, is also the scientific notation for the critical density of the universe, which in turn determines whether it expands indefinitely (ice-death) or collapses (big crunch or fire-death).
Image Credit: Institut de Ciencies del Mar, Barcelona
Astrobiology Magazine (AM): Many people would be surprised at how much of the modern picture of the beginning and end of the universe is from data that are less than ten years old. Were you struck by the 'fresh off the press' nature of this research while writing Alpha and Omega, which is more timeless about a question that goes back to the beginnings of consciousness?
Charles Seife (CS): For me, that was the most exciting thing about writing the book. The questions are ancient and the answers are brand new -- it gave me a sense that I was a witness to history being made. It was like sending dispatches from the front of a scientific revolution.
AM: In your new book, Alpha and Omega, you outline the history behind a quest to understand the beginning and end of the universe. Omega--the last letter of the Greek alphabet-- is also the scientific notation for the critical density of the universe, which in turn determines whether it expands indefinitely (ice-death) or collapses (big crunch or fire-death). How is this number best estimated today?
CS: As far as scientists can tell, omega is equal to 1; it is exactly at the critical density that balances on the knife edge between an indefinite expansion and collapse. (In such a universe, the ultimate end is also ice death.) The components of omega are baryonic matter, which equals 0.04; exotic matter, which equals 0.23; and dark energy, which equals 0.73.
AM: You quote Chesterton: "A cosmic philosophy is not constructed to fit a man; a cosmic philosophy is constructed to fit a cosmos", as a nice paraphrase of the astronomers' creed about not fitting a theory to our view of a special place for humans in the universe, about not being anthropocentric. Would you regard this principle as fundamental to avoiding some of the pitfalls of science history, particularly for a workable cosmology?
|Tycho Brahe, a Danish astronomer (1546-1601), was convinced that the improvement of astronomy hinged on accurate observations.
Credit: Rice University/IMSS Florence
CS: It is crucial -- you can't be ruled by your aesthetic sense of how the universe should be; you have to use data to measure how the universe is. Dark matter and dark energy are ideas that seem foreign to human experience. Worse yet, cosmologists throw around words like "infinite" and "unbounded," which can give almost anyone the heebie-jeebies.
However, I think that what keeps scientists from getting too anthropocentric is the fact that theories are expressed in the language of mathematics, and scientists must go wherever their equations lead them. If the laws of quantum mechanics say that photons can have a weird "spooky action at a distance," then they must or the laws are wrong. If the concordance model says that there's dark matter and dark energy, then they must be there or the model is flawed in a fundamental way. It doesn't matter whether you like the idea of dark energy or dark matter; you must follow the equations to their conclusions, no matter how hard it is to wrap your head around the conclusions.
AM: A remarkable historical fact you quote is that a third of the Danish treasury was set aside for Tycho Brahe's observatory, and that was before the use of telescopes. Why were the Danes so interested in the cosmos at that time? Sea-navigation only?
CS: I think it had less to do with Danish interest than King Frederick's. Brahe had two big things in his corner. In 1572, he spotted a "new star" (in Latin, "nova stella," something that modern astronomers would call a supernova) which helped disprove the idea that the heavens were eternally unchanging. This cemented his fame. In addition, his foster father, the vice-admiral of the Danish fleet, gave his life to save Frederick from drowning. I think that the threat of having a renowned Danish scientist leave the country coupled with Frederick's gratitude to Brahe's foster father led him to offer Brahe such an incredible deal. (And Brahe's lifestyle got accordingly out of control; only in the richest households could you have a trained elk, much less a trained elk that dies while drunkenly falling down the stairs.)
AM: To paraphrase Stephen Hawking, cosmology requires grappling with astronomy and particle physics, and few have been trained well in both fields. Is this a deficiency of curriculum, or more fundamentally about spanning the large and small in a single short lifetime of study?
CS: You're right; cosmology requires both astronomy and particle physics, and each topic is more than a handful on its own. However, an increasing number of people consider themselves "particle astrophysicists," and not all of them are cosmologists. Neutrinos are becoming an increasingly important tool for understanding the workings of the sun (and conversely, solar physics is crucial for physicists who are trying to understand the nature of neutrinos.) It's certainly a lot to learn, but I think more and more students are tackling the subject. Often interdisciplinary subjects can fall between the cracks, but this particle astrophysics is so exciting that I suspect (and hope) that it won't suffer for lack of students.
AM: Astronomers have been accused of seeing the universe in discrete energetic bins: the violent gamma-rays, the exploding X-rays, the ultraviolet, the visible, the hot infrared and finally the quiet microwaves. A galaxy or star or event looks so different, depending on the spectra it is viewed in. Of these, is the cosmology of microwaves one advance that is leading theories today about Alpha to Omega, the beginning and end?
CS: Microwave astronomy is the most advanced at the moment, and it's the lynchpin of the cosmological revolution that's going on right now. The faint, cold light from the 400,000-year-old universe is a Rosetta stone to cosmologists, and it's only been three years since the CMB hunters' vision became clear enough to let them decipher the message that light contains.
A few years ago, microwave astronomy lagged far behind its counterparts in other regions of the spectrum. Now that WMAP has released its initial results, other types of astronomy are going to have to do a little catching up, but they're well on their way. Visual and IR measurements are probably most important to cosmologists, though the higher-energy observatories do contribute somewhat to our understanding of dark matter and a few other things of cosmological interest. And astronomers are no longer limited to photons; neutrino observatories, cosmic ray observatories, and even gravity-wave detectors might one day be crucial, too.
|The SuperNova Acceleration Probe.
Credit: Supernova Cosmology Project, UC Berkeley
Cosmology is data starved, which is why the enormous new influx of data has caused such a revolution. The next revolution might not be so far away.
AM: The current cosmology's lifecycle hinges on a couple of key measurements, by COBE (microwaves), Hubble (visible), balloons (namely Boomerang-microwaves) and the million galaxy sky surveys (Sloan and Two Degree Field in visible). For cosmologists, which class is the next big measurement in the next five years or so? For instance, the 2005 completion of Sloan, or something from particle physics that awaits a bigger accelerator?
CS: All of these areas are going to be important over the next few years. The big one everyone was waiting for was the microwave data from the WMAP satellite, whose first data was released in February. There's still a lot of information coming from the microwave part of the spectrum, but nothing will be quite as splashy as the February announcement.
The galaxy surveys are similar biggies, and they're already making a mark on cosmology. Just last month, physicists compared the Sloan data (which reveals where large chunks of matter are sitting in the universe) with the WMAP data and came up with an independent verification of dark energy with what's known as the "late integrated Sachs-Wolfe effect."
A bunch of key experiments are (hopefully) going to come online and return results closer to the end of the decade: the Planck satellite which will give even more detailed microwave measurements, along with polarization; the Large Hadron Collider, which has a good chance of finding the particle responsible for exotic dark matter; and the SuperNova Acceleration Probe will do for supernovae what WMAP did for the microwave background. It will be a very, very exciting time.
Part II of the interview with Charles Seife continues his conversations with Astrobiology Magazine.
Related Web Pages
A Universe Before Stars: Unraveling the Mysteries of the Earliest Moments in Time
Hunting for the Big Bang's Fossils in the Sky
Supernova Prompts New Look at How Universe Works
Galaxy Evolution Explorer
Hubble Space Telescope
Space Infrared Telescope Facility
Great Observatories Origins Deep Survey
Compton Observatory Gamma Rays
Deep Field South:
SIM (NASA's Space Interferometry Mission
GAIA - The Galactic Census Project
FAME: Full-sky Astrometric Mapping Explorer