Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asked at the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and add-free, plus hours of bonus content,

check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

One day humanity may settle countless boards, but could any nation hope to govern multiple

planets or even star systems?

Most of us grew up on classic space opera science fiction, where multi-planetary empires

are a staple of the genre, and usually it's a sprawling empire composed of many hundreds

or even thousands of worlds spread over the galaxy.

Often these are all connected by warp capable ships or wormholes or jump gates or some other means of

FTL, faster-in-line travel and communication.

We'll discuss those today too, but as general regulars know, we're not very optimistic about

FTL ever happening.

Most examples of theoretically possible FTR that we hear of in science are more accurately

as situations where we're

pretty sure the method is impossible but haven't been able to prove beyond any reasonable doubt

that it is, rather than there being any actual evidence it could be done.

I'm a physicist and I don't think so and I don't know any colleagues who do, but most of us

would love to be proven wrong. Your default warp try runs on negative matter, so do staple wormholes, and that's

material allowed under math but for which there is no evidence that it exists and no

real expectation it does either, much as we don't expect to find a negative dollar bill

or a negative gallon of water outside any accounting chart or spreadsheet.

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