Title:           In order to control gravitational fields like that you would need an incredibly
Author:          Anonymous
Pastebin link:   http://pastebin.com/mC8ufVeD
First Edit:      Saturday 11th of August 2012 07:10:47 AM CDT
Last Edit:       Saturday 11th of August 2012 07:10:47 AM CDT

In order to control gravitational fields like that you would need an incredibly super dense material like dark matter or a fragment of a neutron star, which would be so heavy that, if you were to drop it, it would fall through the Earth and come out the other side before falling back through the Earth. Not to mention just having something with that kind of gravitational and magnetic pull on all of the unicorns at all times would probably fuck up the magnetosphere and kill everypony with a solar storm, or just fuck up the Earth's orbit and send it off into space.
 
Not to mention the amount of energy required to manufacture such a horn... and you're telling me they produce it organically? The mother would have to eat more food than conceivably exists on the planet to produce 1 baby, or she'd have to absorb most of the sun's energy to make 1 unicorn horn. Not to mention their magic wouldn't be controllable (They would also have to be impossibly strong just to lift their super dense horns)
 
I'm sorry guys, but if you want Equestria to be Earth in the future, that means it has the same physics as our universe, which means it's paradoxically impossible.