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.

This episode is brought to you by Brilliant.

For centuries now, we have pushed ever forward with science, unlocking new truths and

new mysteries at every step.

This journey has come to define our modern civilization, but what would happen if one day

that journey stopped, having no further

place to travel forward to?

So I've occasionally discussed in other episodes that there are fundamental reasons to think

that we will get an answer to all the basic universal laws of physics, and from there,

all of science in general, and, this might happen before we even get

into the depths of space. By default, we tend to think that's absurd, that there will always

be more questions to solve, that science is like the mythic mini-headed hydra fought by Hercules,

which sprouted two new heads every time one was cut off. And indeed, this might be the case

for knowledge in general, but for science itself, there's less of a reason to expect this,

and indeed it is quite to the contrary. It's not that we're creating ever new questions,

but that we're speeding up the rate at which we answer a set and finite number of them.

The hydra, in this this case may sprout two heads

each time we cut one off, but it's only got a thousand to sprout, and each new pair

popping up from a stump just makes it faster and easier to whack two off, that the complexity

...