And I mean that in the most cosmic way possible.
We, human beings, have ended up as the most advanced species on a small blue-green planet that orbits a seemingly insignificant star.
One star in one of the hundred billion galaxies out there.
Our existence is the result of an unlikely sequence of cosmic moments.
The most popular models for the origin of our universe suggest that it is one of a countless, even infinite, number of universes.
The models predict that all of these universes vary – stronger gravity, weaker gravity, faster light, slower light.
And, just like in the lottery, among all those universes, there’s one with the winning ticket: our universe.
One universe with exactly the right constants of nature to create the conditions for life.
13.8 billion years ago, our universe came into existence.
The Big Bang, when our universe came into being, seems like the greatest chance event in the history of human existence.
During the Big Bang, the ingredients of our universe were created.
A set of constants of nature (gravity, speed of light, number of dimensions etc.) that seem to be just right for housing life.
Had they been just a bit different, it might quickly collapse.
Or not contain the right chemical elements. Or stars and planets might not form.
Out of the billions of solar systems in our galaxy, ours might never have come into being without another cosmic accident…
4.6 billion years ago, a dying star provided the spark to start our sun.
One theory is that a star was born billions of years before our sun exploded, igniting inert gas in a cloud of cosmic dust.
From this, our sun and a spinning disc of matter (which later became the planets of our solar system) were formed.
4.5 billion years ago Earth was almost destroyed in a chance collision with another planet in our solar system.
Earth survived. The other planet did not.
And the huge amounts of debris thrown into space coalesced into our moon due to gravity.
4 billion years ago, living water arrived from space.
Our young Earth was a ball of molten rock, and any surface water quickly evaporated into space.
Frozen comets crashing into the Earth are one possible source of water.
3.8 billion years ago complex molecules combined to create life.
Without the conditions created so far, Earth would still be a soup of complex chemicals – devoid of life.
2.7 billion years ago a chance collision created complex life.
Up to this point, it had just been single-celled organisms.
But, somehow, two single cells merged and, instead of dying, formed a hybrid that survived and proliferated.
Today, every plant and every animal shares those same basic building blocks, and scientists are very confident that this joining only happened ONCE in the oceans of primordial Earth.
2.4 billion years ago, a new type of bacteria created oxygen.
Before that, most bacteria fed on carbon dioxide and other gases, like methane.
Then cyanobacteria started creating energy in a new way: photosynthesis.
Oxygen was just a waste product of cyanobacteria using sunlight to split water – but over time, the levels of oxygen built up to what we breathe today.
Dinosaurs dominated the earth for over 160 million years.
Until an asteroid, almost six miles across, collided with the earth and blasted rock and dust into the atmosphere.
65 million years ago, Earth was shrouded in darkness and over half of all life was wiped out.
Without this cataclysmic event, our small shrew-like mammal ancestors may have never flourished.
And 1 million years ago, changes in Earth’s orbit may have contributed to our increased intelligence.
The gravity of the planets in our solar system makes Earth’s orbit change how elliptical it is, over the course of thousands of years.
This affects our climate.
Looking at the fossil record, our ancestors’ increases in brain size happened when the Earth’s orbit was at its most elliptical.
This would have meant a time of rapid and violent climate change. Adaptability and intelligence would have been a huge evolutionary advantage.
So, you see, you being here today is quite by chance.
Enjoy it. Savour it. Revel in the uniqueness of it.
Because you’re literally made of stardust.
- What is your favourite season or time of year? Describe why.
- What is your favourite kind of weather?
- What is your favourite place on Earth?