Threats to Our Existence: if we Don’t Wipe Ourselves Out, The Universe Will

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Climate change, nuclear holocaust, super viruses, artificial intelligence: these are all pressing concerns to the safety of humanity, but even if we manage to circumvent these threats we will never be completely safe from extinction. The future of the Earth – and humanity, is riddled with so many apocalyptic forecasts that it makes any religious scripture shy in comparison. Below are the major long-term threats that we can expect to encounter.

Asteroids and comets

A giant asteroid struck the Earth around 66 million years ago and sparked a mass extinction event that wiped out the dinosaurs and many other species. Experts estimate that asteroids of this size strike the Earth once every 100 million years, and if another one of these bad boys hits us today the consequences could be just as catastrophic.

There are thousands of asteroids lurking around our Solar System and some of their trajectories could cause them to collide with the Earth. There is also a cool scenario that occurs once every 45 million years where wandering stars disrupt comets from the Oort cloud and cause a massive increase in the number of comets that reach the inner solar system.

gravitational_tractor
An illustration of NASA’s ‘gravitational tractor’, our best defense against asteroids

Thankfully, we have a decent system for detecting and monitoring objects that may pose a threat to Earth.

In the event of the detection of a large, Earth-inbound asteroid or comet, we would need to have a plan to destroy or divert the object. NASA’s current plan of action involves deploying a ‘gravitational tractor’ which can orbit the object and use its own mass to wean it off its original trajectory. This tractor technique is largely theoretical, so we might need to test it out before we can start sleeping soundly at night.

Death of the Sun

Our Sun, the beautiful, yellow blob in the sky, is responsible for sustaining all life on Earth; however it will eventually turn into a monster that dishes out a series of worsening predicaments, until the Earth becomes uninhabitable.

We can’t wait around for the day when the Sun comes into our room with a creepy smile on his face and the smell of helium on his breath. We have to leave Earth before the sick bastard has a chance to lay his hands on us.

habitable_zone.jpg

During the slow death of our Sun, the habitability zone will shift outwards so that in 1.4 billion years from now Mars will become fully habitable. In 5-8 billion years from now, the Sun will have expanded into a red dwarf, and Mars will no longer be habitable, but Saturn’s moon Titan will become habitable. If we plays our cards right, we will be able to move further out into the solar system, jumping between planets and moons to escape the clutches of our dying star.

We could hang out on Titan for a few billion years until the Sun completely fizzles out. We could harvest planets, asteroids and comets for resources to sustain ourselves, but eventually we will exhaust all of the resources in the solar system, and will have to leave.

Limited resources

We could survive for billions of years, hopping around the galaxy and harnessing the energy of stars (using these nifty contraptions called dyson spheres); however eventually we are going to hit a brick wall. The universe is expanding at an increasing rate and in 150 billion years everything beyond our local supercluster (the Virgo Supercluster) will become completely unreachable.

Observable_Universe_with_Measurements_01.png
The Virgo Supercluster is indicated in the centre of the graphic above, but is too small to be seen. In 150 billion years it will be the only part of the universe that we can hope to explore or even observe. The observable universe will become limited to a single pixel in the centre of the graphic. 

There is a finite amount of matter in the universe, and as the universe continues to expand, every star that passes beyond our cosmological horizon is a wasted opportunity to harness energy and extend our existence.

One scientist thinks that we should spend the next 150 billion years capturing as many stars as possible and confining them to our local supercluster, and I agree with the man. This strategy will allow humanity create a gigantic super galaxy and continue to exist comfortably until star formation ceases in 100 trillion years.

Ultimate fate of the universe

After star formation ceases, planets will get thrown off their orbits and all matter in the universe will decay and fall into black holes. The black holes slowly evaporate via Hawking radiation; and after a gazillion years (around 10^10^76 years to be precise), all of the black holes will be gone and the universe will be empty.

It’s hard to imagine how we will survive all of these cosmic shenanigans, but we have a lot of time to figure it out.

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