The universe is a start-up

Earth is 4.54 billion years old. It was born 9.247 billion years after the Big Bang, which happened 13.787 billion years ago. Meaning that our planet is a third the age of the Universe.

Hydrogen, helium and other light elements formed with the Big Bang, but the heavy elements were cooked up at various times in an 8 billion year span before our solar system was formed, and some, perhaps, are still cooking.

Best we know so far, life appeared on earth at least 3.5 billion years ago. Oxygenation sufficient to support life as we know it happened at the start of proterozoic era, about 2.5 billion years ago. The phanerozoic eon began 0.541 billion years ago year ago, and is characterized by an abundance of plants and animals. It will continue until the Sun gets so large and hot that photosynthesis as we know it becomes impossible. A rough consensus within science is that this will likely happen in just 600 million years, meaning we’re about 80% of our way through the time window for life on Earth.

Some additional perspective: the primary rock formation on which most of Manhattan’s ranking skyscrapers repose—Manhattan Schist—is itself about a half billion years old. (My ass is three floors above some right now.)

In another 4.5 billion years, our galaxy, the Milky Way, will become one with Andromeda, which is currently 2.5 million light years distant but headed our way on a collision course. The two will begin merging (not colliding, because nearly all stars are too far apart for that) around 4 billion years from now, and will complete a new galaxy about 7 billion years from now. Here is a simulation of that future. Bear in mind when watching it that it covers the next 8 billion years. Our Sun, by the way, will likely be around for all of that, though by the time it’s over will a have become a red giant with a diameter wider than Earth’s orbit, and perhaps by then will have gone past that, shrinking down into a white dwarf.

In TIME WITHOUT END: PHYSICS AND BIOLOGY IN AN OPEN UNIVERSE, Freeman Dyson gives these estimates for the future age of the Universe:

TABLE I. Summary of time scales.

Closed Universe
Total duration 10^11 yr

Open Universe
Low-mass stars cool off 10^14 yr
Planets detached from stars 10^15 yr
Stars detached from galaxies 10^19 yr
Decay of orbits by gravitational radiation 10^20 yr
Decay of black holes by Hawking process 10^64 yr
Matter liquid at zero temperature 10^65 yr
All matter decays to iron 10^1500 yr
Collapse of ordinary matter to black hole
[alternative (ii)] 10^(10^26) yr
Collapse of stars to neutron stars
or black holes [alternative (iv)] 10^(10^76) yr

So, at the short end the Universe is now about 1% into its lifespan, and at the long end it’s many zeros to the right of the decimal point. In biological terms, that means its not even a baby, or a fetus: more like a zygote, or a blastula.

So maybe… just maybe… the forms of life we know on Earth are just early prototypes of what’s to come in the fullness of time, space and evolving existence.

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