The Planck spacecraft has discovered that the universe is 100 million older than previously thought. Earlier estimates pegged it at 13.7 billion years. Another 100 million would make it 13.8 billion years old. If I’ve done the math right, that’s 0.7% older. Crunched down to human scale, that would be like waking up today at age 30 and discovering you were suddenly 72 days older.
Planck is a joint European-U.S. venture launched in 2009 to extend the highly successful COBE and WMAP missions that provided astronomers with their first maps of the cosmic microwave background (CMB). Located in a stable region of space called the L2 Lagrangian point, Planck has mapped the CMB in even greater detail since 2010.
When the universe initially formed, it was microscopic, incredibly hot and contained only energy and space. During the first three minutes it expanded and cooled enough for energy to “congeal” into protons and neutrons, the subatomic particles we know as the building blocks of atoms. These in turn collided to form the simplest atomic nuclei of hydrogen, helium and a trace of lithium.
While the initial temperature of the universe was essentially infinite, matter (atoms) formed when it had dropped to a more pleasant 1.7 billion degrees F. This was still too hot for electrons, those tiny particles that whiz around the nucleus of an atom, to “stick” to the newly formed atoms.
For the next 380,000 years, even as temperatures continued to plummet, the universe, with all of its expanding space, energy, nuclei and free-roaming electrons was a dense, impenetrable fog called a plasma. The soup of particles was so thick that photons (particles of light) trying to stream away from one nucleus or electron was immediately scattered away by its neighbor. Light was going nowhere.
Had you been around back then the entire universe would have been a dense cloud, the kind you often fly through in a plane but so thick you wouldn’t have seen your hand in front of your face.
At 380,000 years a major transition happened. Things cooled down to around 28,000 degrees allowing electrons to settle into orbit around the hydrogen and helium nuclei to form neutral atoms. Bound to the nucleus, electrons weren’t available to scatter photons of light anymore. Like a prisoner set free, light streamed unimpeded across the universe for the first time. This ‘”first light” is the cosmic microwave background radiation. The fact that we see it is one of the best proofs the Big Bang really happened.
The Planck map reveals tiny variations in the temperature of that light. These result from what are called quantum fluctuations in the universe present in the moments after its birth. Without getting into fancy physics, they’re changes in the energy content of various points in space that vary chaotically. Those energy “bumps” were frozen into the fabric of space once the expansion ramped up and the first neutral atoms formed.
Billions of years later we see these original fluctuations writ large as temperature variations mapped by Planck. Seen as splotchy hot and cold spots in the Planck map, they’re seeds where matter collected in the early cosmos and grew into the stars and galaxies that populate the universe today.
So you see, the map really shows the origin of matter from jittery, fluctuating energy states of empty space. It’s a relic of the distant past embedded in the first light to grace a fresh-faced universe. The map also suggests the universe is expanding more slowly than originally thought, hence its older age estimate. And there’s more:
“As that ancient light travels to us, matter acts like an obstacle course getting in its way and changing the patterns slightly,” said Charles Lawrence, the U.S. project scientist for Planck at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “The Planck map reveals not only the very young universe, but also matter, including dark matter, everywhere in the universe.”
Toting it all up, the new estimates for the composition of universe include 4.9% normal matter (up from 4.6%), 26.8% dark matter (up from 24%) and 68.3% dark energy (down from 71.4%). Determining exactly what makes up dark matter, which has gravitational pull but can’t be seen since it emits no light, and dark energy, a repulsive force causing the rate of the universe’s expansion to speed up over time, are both fields of active research.
As I look out at today’s blue sky, hear the sound of voices from the street and admire Comet PANSTARRS at dusk, I’m convinced this universe has aged that extra 100 million years with grace.