Analysis of the Probabilities of Earth Extinction Scenarios

No matter how unique Earth is, the planet has a lifespan will only have a few billions of years to support life. So what will humans do once Earth becomes expired? Where can we go? And how long can we beat extinction?

There are several extinction scenarios for humans, such as global diseases, asteroid impacts, and a zombie apocalypse, in the fictional side. But if none of that happens, humanity's last hope to survive extinction is to abandon Earth and travel into space. This is because the Sun and the solar system may not be the same in the next several billion years.

The End of the Sun

According to Northwestern University, the Sun will undergo a supernova after it has exhausted its hydrogen reservoir, just like any other star. Experts estimate that the Sun will have the helium flash, about 1.2 billion years after it left the main sequence stage and at the peak of its red giant stage. The Sun will consume every last of its resources within minutes and explode into a supernova. But before that, the Sun will grow into a massive stellar object, the nearest planets in the solar system like Mercury and Venus will be more exposed to stellar energies. Some astronomers consider that the Sun's energies can potentially increase the global temperatures of Earth.

In that scenario, humans must prepare for the inevitable. If we have the technology to make human space travel beyond the moon, the next planet to colonize is Mars due to its closeness.

The reason why we need to leave Earth as soon as possible is because of the following potential consequences from the large Sun:

• Earth's rocks erode easier under higher temperatures. This exposes new rocks to the atmosphere.
• New rocks decrease the level of carbon dioxide in the atmosphere, which supposedly helps fight climate change.
• The depletion of carbon dioxide, however, has deadly consequences to plants. Plants cannot perform photosynthesis without carbon dioxide.
• Without carbon dioxide to use, plants and trees will die that leaves the planet with significantly less oxygen supply, potentially suffocating animals and humans.

During that time, the Sun may also engulf the first three planets in the solar system. If Mars has been colonized by humans, we may be able to survive for the next several hundreds of years. Eventually, we need to leave soon because the artificial atmosphere of Mars will not withstand solar energies. Moons like Enceladus and Europa are likely going to be water worlds by then, and humans can colonize them to avoid extinction.

The Rearrangement of the Galaxies

Since the Sun will explode, humans need to leave the solar system to avoid the effects of a supernova. Provided we have the technology for interstellar travel, humans can go to the nearest star system like the Alpha Centauri, specifically, the Proxima Centauri system. However, there are certain issues we need to address first:

• An interstellar journey can potentially expose our spaceships to supernovas. If the ships are within range of exploding stars, the energies are expected to destroy the majority of the human colony ships, if not all.
• Proxima Centauri may not be the nearest star system by then. Galaxies move and stars inside them are rearranged constantly. So, we need to regularly track down nearby star systems for changes.
• The Milky Way and Andromeda galaxies are expected to collide in the future based on observational data, according to Space.com. Astrophysicists believe that the solar system will not be hit by the merger and stars are unlikely to collide to one another due to them being too spread out. But, the merger will cause a galactic makeover that alters the positions of every star system. As such the next star system for us to colonize may not be here yet. Also, the collision may happen right before the Sun consumes the inner part of the solar system.

The Heat Death of the Universe

Although we have escaped the supernova of the Sun and the threat interstellar journey, we still have a major problem to face. What happened to our Sun will eventually occur in every star in the universe. Each one will exhaust their fuel, dim out, and leave the universe in complete darkness. The only remaining stellar objects in the darkness of space are black holes. Yet even these stellar remnants may not swirl for eternity.

Stephen Hawking published a study in 1974 to argue that black holes emit particles in space. Though, the emission of black holes is not as strong as any other emissions in the universe. This emission is called Hawking radiation.

Hawking radiation causes black holes to release energy over time and it will induce them to shrink down. Even though it may take billions to trillions of years for one black hole to shrink, the reality of it happening indicates that nothing will exist forever. Once the stars and black holes are gone, the existence of life becomes an enigma since there are hardly enough atoms left in the universe. The lack of sufficient atoms uniforms the amount of energy in space, an energy that cannot do anything. As a result, the heat of the universe finally grows cold.

According to SciShow, by the time humans left Earth and the solar system for interstellar travel, evolution may have kicked in. Humans are likely to become a completely different species with a tiny connection to the original humanity. There is a huge chance that evolution has changed our physical body, removed certain vulnerabilities, and allowed resistance to space radiation. In other words, humans may be able to outrun extinction for a very long time.