Fermi National Laboratory

Volume 25  |  Friday, October 4, 2002  |  Number 16
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Star Light Star Bright
Fermilab Public Affars intern Pamela Zerbinos attends the Cosmo-02, and discovers a field of dreams.

by Pamela Zerbinos

Wednesday, Sept. 18, 2002: Picture This
I have always hoped that if the universe is to one day cease its outward expansion and collapse back in on itself, that this will happen sooner rather than later. It will put me out of the misery of wondering about its expansion ó where is it going? This question makes my head hurt, and I have always avoided cosmology because of it.

So the last place I ever expected to find myself is crammed onto a Chicago Transit Authority ďL Ēcar, headed to Cosmo-02,the annual International Workshop on Particle Physics and the Early Universe, at the Adler Planetarium. The conference is being sponsored in part by Fermilabís Theoretical Astrophysics Group, along with Adler and the University of Chicagoís Center for Cosmological Physics. I am expecting a four-day cosmological extravaganza. I am nervous, but mostly excited.

I have been cramming for this conference for a week ó definitely not enough time. But despite my meager preparation, I feel Iím on pretty decent footing. I think I have the core concepts down: The universe is expanding, and the rate of expansion is increasing. A mere 5 percent of the universe is made of normal matter ó the same kind of quarks and leptons that make up the world around us. The other 95 percent is dark matter and dark energy, and what itís made of is one of the great cosmological mysteries. The Big Bang was not actually a ďbang,Ē not something that happened at a particular point in space and time, but rather was the sudden and simultaneous appearance of matter in all of space.(I canít quite wrap my mind around this concept, but I like the way it sounds ó the Big Ta-da!) The Ta-da! was most likely followed by a period of exponential expansion, which has been dubbed ďinflation.Ē The universe is homogeneous (the same in all places) and isotropic (the same in all directions). It ís flat.

My goal for the conference, other than finding someone who can tell me where the universe is going, is to find out what other cosmological mysteries are out there, how the cosmologists are faring with their attempts to figure it all out, and what the particle physicists are doing to help.

I am waiting for the conference to start, admiring the very nice black leather portfolio that all the participants have been given. The 264-seat auditorium is crowded; there are 265 participants. As I look through the list of registrants, I have two realizations. First, I am approaching physics geekdom ó I recognize some names. Second, this is a very diverse crowd. There are cosmologists, astrophysicists, particle physicists, nuclear physicists, astronomers, string theorists and journalists. I know itís too much to ask that the talks be pitched to the lowest common denominator, but a girl can dream.

Fermilab director Mike Witherell announces in his opening remarks that he was one of the first people not to detect cold dark matter. The Theoretical Astrophysics Group at Fermilab was founded by Leon Lederman in 1983, and although it was an unorthodox move at the time, there are no longer any doubts that particle physics and cosmology share a deep connection.

Cosmo-02 was held at the Adler Planetarium on Chicago's lakefront.

I have heard four talks. I have copious notes on the Cosmic Microwave Background, cosmological parameters and large-scale structure. I am not confused, but this is only because being in a state of confusion first requires a modicum of understanding, which I donít have. The effort of trying to figure out whatís going on has exhausted me. I feel like a zombie. I stick my arms out in front me of me and follow the crowd to lunch.

I have now heard two talks on inflation, one by David Wands and the other by Alan Guth. Thereís one more coming up. I am feeling slightly more human, but now Iím having a visualization problem. Can these speakers actually picture the things theyíre talking about? Does Guth, father of the inflationary universe theory, have a picture in his head of an infinite number of universes? According to him, each second sees the birth of 1037 more universes than the last. Mathematically, this is fine, but I canít see it. I canít touch it. Can anyone? 2130
I am at the Education Forum, where about 45 people have gathered to discuss ways to educate the public about cosmology ó what the public needs to know and how to help them know it. There are many hurdles, the biggest of which seems to be a lack of qualified teachers. Your average junior high or high school science teacher simply doesnít have the background to teach cosmology, and fixing that requires an overhaul in our educational system. This isnít a great prognosis.

After the forum, I bring up my visualization problem to Evalyn Gates, one of the conference organizers. Eureka! Yes, she tells me, cosmologists have problems picturing universal expansion and extra dimensions. But cosmologists can do the math, which provides understanding on a different level.

This I can accept, but I wasnít having any fun thinking that there are people out there who can really wrap their head around this stuff, and Iím not one of them. I feel that one function of being an expert in a highly technical or esoteric field is óor should be ó granting access to that field to the rest of us, and I find it frustrating when the people who say they understand canít help me do the same. It ís comforting to know that we íre all more or less on the same level,and cosmologists just happen to have this extra tool ó mathematics ó that grants them understanding.

The Chicago skyline as seen from the Adler Planetarium

Particle Accelerators to Cosmology
I am optimistic about todayís program. There are some neutrino talks that I think I might understand, and Fermilabís Joe Lykken is giving a talk about accelerators and cosmology that Iím looking forward to. I also know thereís going to be some big news today ó there were hints of it yesterday ó but I have no idea what it will be about.

Lykken described some of the activities and goals of Run II and the LHC,and related it all very nicely to cosmology. Some cosmological questions ó dark matter, baryogenesis, extra dimensions ó can be studied directly in the laboratories, and many particle physics issues ó supersymmetry, string theory ó can provide cosmologists with new ways to think about and study the universe. After all, particle physicists and cosmologists are ultimately after the same thing: cosmic understanding.

Lykken is not the only one who has tied the fields together; Iíve noticed most speakers have been careful to point out why their talk should matter to those on the other side.

John Carlstrom, of the University of Chicago, has just announced the results of DASI, the Degree Angular Scale Interferometer. DASI is a telescope near the south pole thatís been measuring the polarization of the Cosmic Microwave Background. The CMB is radiation left over from the big bang, discovered by Arno Penzias and Robert W.Wilson in 1964. The theories predicted that this radiation would be uniformly polarized, and the results conform exactly to that theory. Light polarizes when it hits something, and the last time any of these photons hit anything was when the universe was about 400,000 years old (its current age is estimated at roughly 14 billion years), when they were bouncing off the cosmic gases that were cooling down to form atoms. If the CMB hadn ít been polarized, cosmologists would have had to rewrite their entire universal framework.

I have a feeling that the lecture I just heard is going to be the most useful one I hear during this extravaganza. It was, again, Alan Guth on inflation, but this time it was open to the public and therefore pitched to the non-expert. Itís helped me draw a lot of connections to talks I heard earlier and has clarified many things. He went over a few theories (inflation,cosmic acceleration, the supporting evidence and some of the kinks in the system, and he did it in a humorous and understandable way.

The Universe Is Weird
I have just woken up from a fitful sleep. I have been dreaming about neutrino eigenstates. I don ít even know what an eigenstate is (other than a type of Rottweiler). In my dream I was hacking up neutrinos with a machete, and putting the different pieces together. The pieces were the eigenstates. I go back to sleep.

The 264-seat auditorium was crowded. There were 265 participants.

Todayís menu consists of weird topics: branes, extra dimensions, strings and dark matter. I canít decide if Iím excited or worried. These are all things Iím interested in, but Iím not sure Iíve absorbed enough to be able to understand any of it. If I havenít, itís going to be a very long day.

1200 Itís been a long day. Iíve understood a fair bit ó definitely more than I did yesterday ó but now my head is swimming in extra dimensions, trying to figure it all out. I met a soon-to-be physics graduate student at the University of Chicago who has been just as confused as Iíve been. I feel a small twinge of guilt for taking comfort in other peopleís confusion, but just a small one.

I decide that my cosmological education would be best enhanced by finding a quiet corner of the planetarium and finishing some books (Iíve been reading Guthís book on ó surprise ó the inflationary theory, and Brian Greeneís book on string theory).

Catalog of Universes
For the most part, todayís talks have been about dark matter and dark energy. Iím understanding more and more, and the dark matter frontier actually looks very promising. Most people are predicting theyíll have it figured out in the next 10 years or so. Dark energy theyíre less sure about, although they have been optimistic.

The conference is wrapping up. Iíve been impressed with the organization (especially the food ógood cookies), and although it felt like it was about 50 degrees in the auditorium, I think Gates, Chicagoís Sean Carroll and Fermilabís John Beacom, the organizers, did a great job.

The closing remarks were by the string theorist David Gross, and I think it speaks well for the conference that an ďoutsiderĒ was chosen and was so well received. He, like most of the speakers, did a good job of tying various fields together.

He also brought up something Iíve been suspecting for the last day or so: Cosmology is currently in a state very similar to the one particle physics was in 30 years ago when the Standard Model was emerging. Cosmologyís own standard model is starting to settle out, built on the big bang theory and the inflationary universe. Experiments are lining up beautifully with predictions, and thereís excitement in the air.

ďIn the Sears & Roebuck catalog of universes,Ē Beacom tells me later,ďwe now know which one is ours.Ē

It ís a comforting thought.I think.

On the Web:
Fermilab Theoretical Astrophysics Group:
Adler Planetarium & Astronomy Museum:
University of Chicago Center for Cosmological Physics:
http://cfcp.uchicago.edu/ DASI results:
(image at www-news.uchicago.edu/releases/photos/polarization/polmap_press.jpg )
Starry Messages:

last modified 9/17/2002   email Fermilab