Thirteen billion seven hundred ninety-eight million years ago (give or take thirty-seven million years), an unimaginably small, massive, timeless point erupted. Time and space sprang into being.
What came before that is a question that may or may not make sense (as time itself is said to have been tied up in that initial singularity). At any rate, for now it is a question for philosophers as much as for scientists. Whether there was a “before”, either temporally or causally, we pick the first moment of the singularity’s expansion as our starting point for this calendar.
The earliest moments of January first on the Cosmic Calendar are taken up with a fury of growth and change. There was a period of exponential expansion. Speculation is that some (still mysterious) process generated a slight excess of matter over antimatter (one part in 30 million), leading to a present universe with matter dominant over antimatter.
About ten nanoseconds in, the universe cooled to the energies we can produce in particle physics experiments today. Around a microsecond, we started getting protons and neutrons out of the particle/energy soup. In the first few minutes, we started getting deuterium and helium nuclei forming.
That’s actual nanoseconds and microseconds and minutes. On the one-year scale of the Cosmic Calendar, all of this is happening unimaginably quicker. Why not watch a (safe and responsible) fireworks display. If a firework happens to go off right at the stroke of midnight, then the chemical reactions driving that explosion could be thought of as an extremely slow-motion recreation of an event that is materially, energetically, and temporally completely unlike the big bang. (But it makes a nice symbol, no?)
Following the initial explosion, it was all about energy. Most of what there was in the universe was just energy. After several thousand years, matter (protons, neutrons, electrons, etc) began to dominate the picture. Exactly when did this happen? I am unable to pin down a clear answer. This scantily-referenced paragraph on Wikipedia says 70 thousand years, which would point to a calendar time two minutes and forty seconds after midnight. This university teaching page says 50 thousand, which is one minute 54 seconds into the year. At any rate, if your energy levels to drop in the first three minutes of the year, I suggest consuming some form of matter – nachos perhaps, or vegetables. Aside from hydrogen, the most common element (bare nuclei, not stable atoms at this point) was helium. But I am very definitely not recommending that you use helium balloons to alter your voice. It might be appropriately reverent, but we are past peak helium, so it would also be irresponsible.
Between 377 000 and 487 000 years after the bang (that’s 00:14:22 to 00:18:33 on New Year’s Day), recombination and decoupling occurred. Recombination is when the first complex atomic nuclei, such as deuterium and helium, formed. Decoupling meant that photons started being able to fly free, rather than always slamming into bits of matter. This meant something new – something that we can observe today. You see, some of those photons are still zipping along. We can detect them now as the Cosmic Microwave Background Radiation. If you like, you could celebrate this by spending those four minutes watching snow on an old analogue television set. Or you could listen to John Cramer’s audio reproduction (available in 20-second, 50-second, 100-second, 200-second, and 500-second versions).
Now we’re well into the New Year – on our way to the universe as we know it. I don’t have any more milestones for this first day, so perhaps we should all get some sleep.
What is your favorite part of this opening fiesta of generation and diversification? Can you spot any interesting events or transitions that I’ve left out of this description?
Fireworks image: “Fireworks white red“, by Tuan Hung Nguyen, Public Domain