Dispatches from the birth of the Universe: sometimes science gets luckyScientific breakthroughs can come in unexpected ways.
by John Timmer - Jun 3, 2012 6:00 pm UTC
Timeline of the Universe—the expansion of the universe over most of its history has been relatively gradual. The notion that a rapid period "inflation" preceded the Big Bang expansion was first put forth 25 years ago.
NASA picture:
For the generations that grew up with TV before the age of cable, the box in our living room was a time machine, capable of taking us back to just a few hundred thousand years after the birth of the Universe. We just didn't realize it. Nor did the scientists that discovered this, at least at first. But luck seemed to play a large role in one of the biggest discoveries of our lifetime.
That may not have been the intended message of the discussion called "Dispatches from the Birth of the Universe," hosted by the World Science Festival on Friday. The panel provided a good picture of our current state of knowledge on the birth of the Universe, and a glimpse at what we'll likely find out next. But the history of the field turned out to be ripe with examples of things that were both hiding in plain sight (but required a bit of luck to spot), and others we've been lucky to see at all (well beyond the luck of being the right age to have seen the TV static).
Lawrence Krauss, who moderated the panel, introduced it by turning on an old TV set on stage. When turned to an empty channel, the TV displayed a familiar wall of static. About one percent of that noise, Krauss said, comes from the Universe itself, a remnant of an event that took place roughly 13.7 billion years ago. That's when, 375,000 years after the Big Bang, the Universe finally cooled enough that protons could hang on to electrons, forming hydrogen atoms and emitting photons in the process. These photons, stretched out and cooled by the expansion of the Universe, have been with us ever since. And, with just a regular old TV set, you can capture some of them.
But, even after the birth of television, nobody realized what it was. It was only fully recognized when two researchers at Bell Labs, Arno Penzias and Robert Woodrow Wilson, tried to get rid of it. As a video narrated by Wilson described it, they were attempting to detect faint microwave signals, and needed to get rid of all sources of background noise. They kept failing, though it wasn't for lack of trying. They checked whether it was the result of atomic testing (it didn't decay), whether it might be coming from New York City (which was visible from the site of the instrument), and even cleaned years of pigeon guano out of the hardware. They simply couldn't get their instrument to read a zero value.
Eventually, someone introduced them to Princeton's Robert Dicke, who had been predicting the existence of this microwave noise, and was gearing up to look for it. Dicke interpreted Penzias and Wilson's data for them, leading to their eventual Nobel Prize.
But the background they detected from Earth was smooth, while we know the Universe is lumpy, filled with complex structures. With time, theorists began predicting several different ways that these structures might have come into existence, several of which would leave their marks on the Cosmic Microwave Background (CMB) found by Penzias and Wilson. (Although Krauss admitted he was betting, on theoretical grounds, we wouldn't see anything).
John Mather, another panelist, made it his graduate project to find out whether these variations could be seen. Unfortunately, the balloon-based instrument he helped make failed in flight, and he struggled just to finish his degree. His next job was at NASA's Goddard Institute for Space Sciences and, while he was there, NASA put out a call for proposals for a science satellite to be sent into space. "My experiment failed, but it should have been done in outer space anyway," Mather said. "Our paper [describing our proposed satellite] said 'we're really smart, and we can figure this out.'"
NASA liked the idea, but it took them 15 years to actually build and launch the result, the Cosmic Background Explorer, since building the Hubble was sucking up lots of NASA's funding at the time. This turned out to really lucky for Mather, since the detector technology doubled its sensitivity during the delay. If it weren't for these improvements, COBE might not have seen anything. Instead, it revealed tiny fluctuations—one part in 100,000—that were the remains of quantum fluctuations that took place as the Universe entered its inflationary stage. Most of the structure in our Universe dates back to these tiny differences.
Princeton's David Spergel, had been working on a competing explanation, admitted "to be honest, I was a little depressed for a while" following the COBE results. His approach "Was a beautiful idea, mathematically elegant, got a few papers on it. Turned out not to be how Nature worked." But luck played a role again.
Spergel helped organize a workshop to discuss the COBE results and, at it, someone boldly proclaimed that they indicated the Universe had a specific geometry (it was flat).This bugged Spergel, since he didn't think there was any way to tell that from COBE's data. But the comment got him thinking—what would you need to do to demonstrate the Universe was flat? The end result was Spergel becoming a member of the team behind the WMAP probe, COBE's follow-up,
which demonstrated that the Universe was flat (along with a number of other things).Although the tiny fluctuations in the CMB are consistent with a Universe shaped by inflation, they're not a direct signature of inflation itself. That may be hiding in the polarization of the CMB's photons, which would bear the signature of the gravity waves unleashed by inflation. Amber Miller is prepping a telescope to be launched by balloon from Antarctica that should detect this polarization, if it exists. And she's already had a bit of luck.
Her team at Columbia is responsible for putting together the mirrors and support hardware; the camera is being built at the University of Minnesota, while NASA will be responsible for its flight from Antarctica. Assembly at a NASA facility in Texas was supposed to start just days earlier, over Memorial Day weekend. Except the camera didn't show up. It didn't show up on the day after the holiday, either. The team eventually tracked down the driver of the shipment, and found that the trailer had gone missing. After a few days of panic, they located it. Some items—Miller mentioned bicycles and a step-stool—were missing, but the camera had been left behind by the thieves.
If all goes well, the next chapter in CMB exploration will be lofted above the atmosphere in December.
And Mather? He's still benefitting from Hubble-related luck. When Hubble was designed, everyone thought galaxies only formed late in the Universe's history. As it turned out, the Hubble spotted many young ones, but couldn't image the wavelengths that captured the era in which they formed. Mather is now leading the team building the James Webb space telescope, designed to image the formation of the first structures in the Universe, the progeny of the CMB's fluctuations.
