Why dividing Earth into two separate hemispheres is even harder than one might assume.
Dear Evil Engineer,
We hope you are able to receive this message, which we are transmitting from a communications outpost located a few light-years from Earth.
Our observations suggest that your planet remains unaware of the ongoing scramble for the planets of the Orion Arm between ourselves and our rival empires. Territorial claims have largely been settled with limited planetary destruction – however, the planet Earth, with its rich resources of water, oxygen and coffee beans, remains subject to competing claims. We have therefore signed a treaty agreeing to the partition of Earth between ourselves and those cretins from Scutum-Centaurus. We will decide afterwards who will take the northern hemisphere and who will take the southern hemisphere with a simple waveform collapse… we hope this news is not excessively distressing.
Despite our being two galaxy-spanning empires with all the unimaginably advanced technology that success implies, both of us are conveniently ignorant when it comes to knowing how to separate planets into two hemispheres. Do you have any advice on how we could proceed?
Yours,
The Ambassador from Perseus
Your Excellency,
Thank you for the helpful information. I warmly welcome you to our humble planet and would like to offer any service I can – I will begin, as you suggest, with advice on how to divide Earth in two.
The most obvious approach is to drill through the Earth’s crust, mantle, and core, all the way around the equator as though working a knife around a watermelon. (This would, of course, require an astronomical quantity of power, but given the scale of your interplanetary empire, I will assume that power is not a limiting factor for you.) Drilling into Earth becomes very hard very quickly due to the mounting heat and pressure beneath the surface. The deepest artificial hole, the Kola Superdeep Borehole, reached less than 1/500th of the way into the radius of the Earth before the effort was abandoned, with countless drill bits ruined by the extreme conditions encountered at this relatively shallow depth. At greater depths, the heat and pressure is so extreme that any ‘gap’ drilled gets immediately filled in by molten rock – you might as well try to slice a liquid.
This problem – of dividing Earth rather than just cutting into it – is an almost impossible one to overcome. If, instead of a drill bit, you used an energy beam that vaporised a section of Earth as it cut through it, you would still be left with the problem of the Earth’s liquid insides immediately reforming into a whole. And if this energy beam cut through the entire Earth in a fraction of a second, gravity would still pull the two halves back together rapidly, causing a devastating earthquake in the process.
How about if you created a physical barrier between the halves of the Earth, such as with an astronomical meat-cleaver somehow resistant to gravitational collapse? There would remain the problem of separating the two pieces of Earth. Any impact or explosion large enough to push them apart (such as by diverting a large Theia-sized asteroid or detonating billions of nuclear weapons) would wreck them.
Even if the two halves were separated by teleportation, Earth would be damaged beyond any use. The edge near the cut plane would immediately experience extreme weather as the atmosphere is pulled over the edge, while the exposed liquid plane itself would deform. The diminished gravity would allow much of the atmosphere to leak away into space. The planet’s magnetic field would be lost, leaving the half-planet vulnerable to solar radiation. Over time, the two pieces would collapse into spheres between the sizes of Mars and Venus in a devastating, violent process unlikely to leave much life on the surface.
When it comes to trying to separate the Earth into halves, any possible approach is either not powerful enough or it is so powerful that it destroys everything in the process. Is there any glory in staking your claim to half the Earth if it means losing the resources you desire in the process? I hope you will agree with me that the answer is no.
I would like to suggest a compromise that could be satisfactory to yourself and your rival empire, and less unsatisfactory to us. How about dividing the hemispheres of Earth by building an enormous armed wall around the equator? This is the traditional way for us – and we would be honoured to share our traditions with you, our future overlords.
Yours,
The Evil Engineer
