Knocking on Heaven's Door - Lisa Randall [171]
Robert Wilson, who was a detail-oriented gadget technology geek, and Arno Penzias, who was more of a big picture scientist, both worked there, and together used and developed radio telescopes. Wilson and Penzias were interested in science and technology, while AT&T was understandably interested in communications, so radio waves in the sky were important to everyone involved.
While pursuing a specific radio astronomy goal, Wilson and Penzias found what they initially considered a mysterious nuisance that they simply couldn’t explain. It seemed to be uniform background noise—essentially static. It wasn’t coming from the Sun, and it wasn’t related to a nuclear test from the previous year. They tried every explanation they could think of, most famously pigeon droppings, in their nine-month attempt to figure out what was going on. After considering all imaginable possibilities, cleaning out the pigeon droppings (or “white dielectric material” as Penzias called it), and even shooting the pigeons, the noise still didn’t go away.
Wilson told me how lucky they were in the timing of their discovery. They didn’t know about the Big Bang, but Robert Dicke and Jim Peebles at Prince ton University did. The physicists there had just realized that one implication of the theory would be a relic microwave radiation. They were in the process of designing an experiment to measure this radiation when they discovered they had been scooped—by the Bell Lab scientists who hadn’t yet realized what they had discovered. Luckily for Penzias and Wilson, the MIT astronomer Bernie Burke, who Robert Wilson described to me as the early version of the Internet, knew about the Princeton research and also the Penzias and Wilson discovery. He put two and two together and brought the connection to fruition by bringing the relevant players into contact.
This was a lovely example of science in action. The research was done for a specific scientific purpose that could also have ancillary technological and scientific benefits. The astronomers weren’t looking for what they found, but they were extremely technologically and scientifically skilled. When they discovered something, they knew not to dismiss it. Their research—while looking for relatively small phenomena—resulted in a discovery with tremendously deep implications, which they found because they and others were thinking about the big picture at the same time. The discovery by the Bell Lab scientists was accidental, but it forever changed the science of cosmology.
The cosmic radiation has proved to be a tremendous tool—not just for confirming the Big Bang but for turning cosmology into a detailed science. The cosmic microwave background (CMB) radiation gives us a very different way of observing the past than traditional astronomy measurements.
In the past, astronomers would observe objects in the sky, try to determine their age, and attempt to deduce the evolutionary history that produced them. With the CMB, scientists can now also look directly back in time before structure such as stars and galaxies were even formed. The light they observe was emitted long ago—very early in the universe’s evolution. When the microwave background we now observe was emitted, the universe was only about one-thousandth its current size.
Although the universe was originally filled with all types of particles—both charged and uncharged—once it cooled sufficiently, 400,000 years into its evolution, charged particles combined together into neutral atoms. Once this happened, light no longer scattered. Observed CMB radiation therefore arrives directly from about four hundred thousand years into the universe’s evolution—unhindered and uninterrupted—to telescopes on Earth and on satellites. The background radiation Penzias and Wilson