Are portals possible?

In a video game series called Portal, we are given a gun, which shoots two portals: an orange one and a blue one.

These portals have the following properties:

• Anything that goes into the orange portal comes out of the blue portal (instantaneously), and vice versa.

• Only two portals may be fired at any one time; if another blue (orange) portal is fired, then the already-existing blue (orange) portal will disappear and be replaced by this new portal.

• Portals can only be fired onto flat, stationary $^1 \ $ surfaces. If a portal is fired onto a stationary $^1 \ $ surface, and the surface then moves $^1 \ $, then that portal will disappear.

• Portals may not coincide (i.e. two portals can't be in the same place at the same time)

• When an object travels from one portal to the other, momentum is conserved, relative to the portal normal. i.e. $p_{\text{initial}}=p_\text{final}$, or, in other words, if a body enters one portal with a given velocity, it will exit the other portal with the same velocity.

This picture succinctly demonstrates what's going on:

Now, assuming that such we can create such a gun, does the existence of these portals contradict any of the laws of physics? Is their existence possible, in theory?

$^1$ Relative to the planet that both the gun and the portal are on. For some reason, if the gun and the portal are on different planets (say, if you shot a portal from the Earth to the moon) this rule doesn't apply.

posted almost 10 years ago

alexqwx‭

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