[MUSIC]
(sound of static)
In 2009, when television converted to digital broadcast, the beginning of the universe went
off the air. A small amount of the crackling static on an old TV was radiation from the
universe’s youngest days.
In the first few seconds after the Big Bang, the universe was a sea of free electrons and
atomic nuclei, so unbelievably hot and dense that not even photons could escape that opaque
cosmic pinball machine.
Eventually, a few hundred thousand years later, things spread out and got cool enough that
neutral atoms could form, and the first light finally went streaming out in every direction.
For a while, like a-few-hundred-million-years-while, those first photons were the only light in
the universe, until early atoms condensed to form the first stars.
Today, light from stars is the only glow we can see in the night sky, but in every direction,
hiding in the background, is the first light, the earliest picture of the universe we can
see: The cosmic microwave background.
It gets that name because along their 13.7 billion year journey, those first photons
have been stretched and cooled by the expanding universe, drawn from visible wavelengths down
to microwaves and radio waves.
Even though you can’t see it with the naked eye, you can still catch it. Every time you
tune your FM dial between stations, you turn your radio into an accidental telescope, just
not a very good one.
But that’s fitting, since the discovery of the cosmic microwave background itself
was a radio accident.
In 1964, Arno Penzias and Bob Wilson at Bell Labs were trying to use a giant radio dish
to bounce transcontinental radio communications off big shiny balloons placed in orbit: Project
Echo.
I guess before cell phones, we were willing to try anything!
The Bell Labs dish in New Jersey had to be incredibly sensitive to pick up the weak signals,
which also meant it picked up a lot of natural interference. But even after correcting for
all that, Wilson and Penzias couldn’t get rid of one mysterious bit of static…
(sound of static)
No matter where in the sky they pointed the antenna, day or night, the static was there.
It didn’t come from our sun, or anywhere else in our galaxy. They even cleaned the
pigeon poop off the dish, and still, the noise continued.
When they heard that other scientists, formulating the foundations of the Big Bang Theory, were
going in search of microwaves precisely in the range they heard their mysterious static,
they suddenly realized what they had found. The echo of the Big Bang.
The splotches in the cosmic microwave background are tiny fluctuations in density, just 1 part
in 100,000, that gave the universe just enough gravitational lumpiness to let little blips
condense into bigger and bigger blips, eventually seeding the stars, galaxies and galaxy clusters
that make up our everything. This early picture has helped scientists explain why the universe
looks the way it does today.
So whether you’re basking in the young light of the noonday sun, or standing under the
ancient light of the stars at night, remember you’re always bathed in the forever-light
of the cosmic afterglow.
Stay curious.