Apocalypse Now

This post originally appeared in Finnish on the Nörttitytöt blog.

*****

Earthrise via NASA (http://www.nasa.gov)
Earthrise via NASA (http://www.nasa.gov)

As I am sure anyone who has not lived in a cave for the last couple of years already knows 2012 is the year the world ends. Everybody and their mother seems to have a theory of what horrors we have coming for us in December, but they do agree that’s when it’s going down.

If they are to be believed, we are facing our last summer. One after another however each of this year’s predictions have been debunked: Planet X doesn’t exist; the planets are aligned just so once a year, every year; the Mayan calendar simply ran out of pages (figuratively). Nothing, however, lasts forever. Not our solar system, to say nothing of the planet, not even the galaxy. The end of the world will come sooner or later. Therefore, I thought to share with you some of the ways in which that final The End could actually come about. I don’t want to deal with what might be caused by humans, not only because they are the most boring but also because they’ve been the most discussed, starting with Dr. Strangelove several decades ago. Here I want to focus on the ways in which our own planet as well as the Universe that we live in can destroy us.

Oxygen go bye bye

Earth’s history has so far known five mass extinctions, when most of the species alive at the time simply died. In four of these extinctions have been caused or aided by anoxia. Anoxia occurs when the seas are running out of oxygen and most if not all of the sea ends up a completely oxygen-free zone. This generally caused extinctions under the surface but also over it, seeing as the seas work as the lungs of the earth. Anoxia usually coincides with an increased atmospheric carbon dioxide concentrations some 4-6 times higher than the current level. After anoxia begins, it is difficult to stop because it acts as a chain reaction. Most marine plants are killed, as oceans generate hydrogen sulfide because atmospheric carbon dioxide reacts with the water, which reduces the supply of oxygen, which in turn increases the amount of hydrogen sulphide.

Venus ahoy!

Anoxia, of course, is not the only problem that excess carbon dioxide in the atmosphere leads to. On Venus, they have a hellish 460 ° C temperature, which can apparently be blamed on a thick, carbon dioxide-rich atmosphere. Historically larger than normal amounts of carbon dioxide in Earth’s atmosphere have been caused by particularly strong volcanic periods. Venus is, with the exception of the atmosphere, very similar in many ways to the Earth, its size and composition are almost entirely alike. But oh that atmosphere… It consists essentially of carbon dioxide, which causes the runaway greenhouse effect on the planet on a scale that is difficult to imagine for Earth. Like anoxia, current data suggests that a greenhouse effect, once it gathers critical mass, is very difficult to stop.

Black hole calling

A black hole is formed when a star about 20 times the size of our own sun dies. As a massive star explodes in a supernova the core’s nuclear reaction does not shut down; the star continues to collapse toward its core until the core’s gravity grows so large that not even light can not escape. A recent study found that black holes grow while feasting on material from stars and planets it swallows. This happens, for example, to the supermassive black hole at the heart of the Milky Way. It eats the stars and planets, which come across its path, causing its gravity to increase, leading to more and larger star systems being swallowed, which in turn results in a higher gravity, and so on and so on. It’s entirely possible that will be Earth’s fate too.

The sun explodes

As I’ve mentioned already we are all made of stardust. Stars are basically a continuous nuclear reaction in which hydrogen atoms turn into helium atoms which in turn turn into heavier atoms all the way up to iron. However, our own Sun is small enough that it will start to die when it runs out of hydrogen. When this occurs it begins to vomit atoms from its shell, until only a white hot core remains. This is very unfortunate for the Earth as the atmosphere will burn as will everything still on the surface.

Andromeda rising

James Gitlin via the Hubble Space Telescope(http://www.spacetelescope.org/)
James Gitlin via the Hubble Space Telescope(http://www.spacetelescope.org/)

If we can overcome all of the previous disasters, some 3-5 billion years from now our beautiful, blue planet will quite likely meet its end. The closest galaxy to our own Milky Way is called Andromeda and unfortunately it’s on a collision course with our own. Galactic collisions are bound to be a truly epic show: the stars orbit each other until they explode in a huge supernova, creating new stars; planets collide, creating asteroids and new planets; black holes orbiting each other until either one is thrown away with enormous speed or they combine to form a larger a black hole. The probability of survival for any life in either galaxy approaches zero but is not necessarily equal to zero. That calls for:

Heat death of the Universe

If by some miracle we can manage through all of the above events, the final judgment will come when the universe stops expanding. Since the Big Bang the Universe we “know” has expanded continuously. The reason is not yet fully understood but one thing is certain; the universe is expanding and while it does so, it’s losing heat and doesn’t seem to be slowing down. Either it will continue expanding until all of the heat is lost and it is entirely in a temperature of 0 Kelvin. The absolute zero temperature is funnu in that it’s when all movement stops, even at the atomic level. Of course there are theories that the Universe will expand until there is not enough energy left to expand more, after which it will collapse in on itself in an inverted Big Bang (although this theory seems to have less support than the ultimate heat death). Whichever it will be, it will be a certain ending for us.

One consolation in all this however can be found; the end of the world will hardly be in our lifetime.

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