Defense strategies in space differ drastically by orbit. Low Earth Orbit (LEO) is protected by having so many assets (proliferation) that an enemy can't destroy them all. The vastly larger MEO and GEO require highly mobile 'bodyguard' spacecraft that can move rapidly to counter threats.

The debate over broadcasting messages to aliens is moot. Astrophysicist Sara Seager argues any civilization capable of interstellar travel would first detect the oxygen in our atmosphere—a highly reactive gas that signals life—making our attempts at hiding irrelevant.

To counter devastating laser attacks on fixed targets like planets, a civilization's best strategy is to "starlift" material from stars and use it to power billions of mobile habitats on randomized orbits. This makes the civilization a diffuse, unpredictable "fog," rendering targeted bombardment ineffective and ensuring survival.

The Fermi Paradox—where are the aliens?—can be explained by the "Great Filter" theory. Astrophysicist Alex Filippenko believes this filter is likely in our future, meaning civilizations like ours often destroy themselves before colonizing the galaxy.

Because mature, distributed civilizations are nearly impossible to dislodge due to defensive advantages, the long-term control of galaxies is determined by who colonizes them first. This brief "settlement phase" has permanent consequences, making the actions of nascent spacefaring species like humanity incredibly impactful.

Combat in space or on the moon will be swift and catastrophic because spaceships and habitats are inherently fragile. Due to severe mass and volume constraints, they cannot be armored effectively. The winning strategy is not to withstand a hit, but to avoid detection, targeting, and being fired upon entirely.

The "Dark Forest" theory posits that civilizations must preemptively destroy others to survive. However, the immense defensive advantages in intergalactic space make conquest economically irrational and nearly impossible. This suggests the universe will likely settle into a stable patchwork of isolated civilizations, not a state of constant war.

The core AI risk argument is that a being much smarter than humans will alter the planet to suit its objectives, potentially causing our extinction. This mirrors how humans, as the "superintelligence of the natural world," have transformed the environment and driven other species to extinction.

Astrophysicist Sara Seager reframes the Fermi Paradox, suggesting advanced civilizations might not contact us for the same reason we don't talk to ants. We are simply not interesting enough to warrant their attention or energy, even if they are studying us from a distance.