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.

Soon, humanity may reach out to the galaxy and spread ourselves to every world in it,

but in the billions and billions of years to come, on those billions and billions of worlds,

humanity shall surely diverge down many roads and post-human pathways.

Records of the entity known as the Spirit of the Air are sparse, and best known from the account

known as the House of Sons, given by Porcelain Gentian of the House of Flowers, recorded

six million years from when humanity first left Earth,

but accounts agree it had once been a human and born in humanity's original solar system,

sometime in the third or fourth millennia. Those were early days when the first interstellar

ships were heading out, and many pursued various post-human pathways and life extension

through relativity or cloning, often shattering their consciousness into many bodies at once,

to explore the galaxy and ensure no cataclysm could get every copy. His name had been Abraham

Valmick, or something similar, a man of immeasurable wealth and

considerable longevity, who nonetheless wanted more out of the universe than it had so far given

him. For Valmic, neither shattering, time dilation, nor biological transformation

offered sufficient guarantees, he wished instead to make himself into a machine,

so that his consciousness might be embodied in something as close to indestructible as physics

allowed. Neuron by neuron, he allowed his brain to be supplanted by mechanical parts. Since the process

was gradual, akin to continuous redevelopment of a city, rather than sudden

...