One of the necessary conditions for the universe to have achieved a state in which it is completely dominated by matter is that it had to pass through a period of non-equilibirum. A moment of rapid expansion, or *inflation*, near the beginning of time would have been just such a non-equilibrium state. How do you figure out that such a thing happens, when it’s been “13.73 billion years since the beginning of time?”:http://lambda.gsfc.nasa.gov/product/map/dr2/pub_papers/threeyear/parameters/wmap_3yr_param.pdf.
Nobody was there – how exactly can you figure it out?
You have to look for evidence left over in the modern universe of such a thing. A candidate for such an observation is the cosmic microwave background radiation, the light that was freed from the hot universe as it cooled and became electrically neutral. This happened about 300 thousand years after the beginning of time, and that light has been traveling the universe ever since, cooling as space expands. The WMAP satellite is the first of a modern series of precision instruments capable of scrutinizing the cold, cosmic microwave background. Three years ago, its results stunned the physics community by ushering in the era of “precision cosmology” – the precise determination of things such as the matter density and age of the universe. All of this, just by peering at the cold light leftover from the big bang.
Now WMAP has even more data, and its three-year results are available. “Early readings of their conclusions point to the existence of inflation in the early universe”:http://news.yahoo.com/s/ap/20060317/ap_on_sc/cosmic_inflation;_ylt=AgZnK_d6WNosfeAbQKk6osas0NUE;_ylu=X3oDMTA3b2NibDltBHNlYwM3MTY-.
The power spectrum of the CMB is affected by the rate of expansion of the universe at early times. The actual spectrum appears to favor a model in which the universe inflates rapidly. While more data is clearly needed, this is already a really striking result and no doubt will drive investigations into the theoretical physics behind inflation.
Today is an exciting day: the WMAP collaboration (Wilkinson Microwave Anisotropy Probe) has “released its three year data and data analysis”:http://lambda.gsfc.nasa.gov/product/map/current/map_bibliography.cfm. I’ve just started looking through their results, but there is no doubt the precision cosmology they were able to do three years ago is even more exciting now! Recall that last time they released results, they became the the conclusive, precision evidence that the universe is indeed dominated by dark matter and dark energy, and not the normal matter we know so much about. That was a revolution in our thinking about this universe.
Jodi is currently in La Thuile, a mountain skiing town in northern Italy. She’s not there to ski, though – she’s presenting a comprehensive overview of direct-detection dark matter searches at the “20th Rencontres De Physique De La Vallee D’Aoste: Results And Perspective In Particle Physics”:http://www.pi.infn.it/lathuile/lathuile_2006.html. She’s one of many particle physicists converging on La Thuile right now, and over the next three weeks, for a series of high-profile “winter conferences”, one of two conference seasons that define the focal points of our field.
And thanks to the magic of “Skype”:http://www.skype.org, I can talk to her for free half a world away. I was able to chat with her after she awoke this morning (Italian time, 9 hours ahead). She’s still adjusting to the time change, but she’s already run into friends old and new and is excited about the start of the conference. Meanwhile, I spent the day making last preparations for the trip to Washington.
This weekend, as in last weekend, the San Francisco bay area is under a severe wind advisory. Last weekend, this meant nearly 100 mph winds in the bay around San Francisco, and 50 mph winds where I live. A series of rather unpleasant winter storms, gliding down the coast from Alaska, have wrought havoc on California these past weeks.
Much like the wind gusting over my house, progress in my research often comes in huge fits that knock over fences and bow windows. The several research project I work on in the BaBar Collaboration are all accelerating at an exciting and feverish pace. As I wrote over a week ago, on the eve of my collaboration meeting, I was obsessed with making progress on research I had only tasted in spoonfuls over the past few months. The meeting itself brought great ideas, and this week saw rapid progress on many fronts.
There is nothing more satisfying to a physicist than to actually move forward on something which once seemed fruitless but always should have been fruitful. I guess wishful thinking can sometimes be the savior of a project, but only when there actually is an interesting side to it. On all of my research fronts, this week brought great leaps forward. If I can keep this kind of progress up, while still keeping my health, I suspect that summer will be most exciting for me.