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

we're asking 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.

Many think fission has gotten a bad rap, but modern reactor designs and the demand for clean power may redeem what was once thought to be an energy panacea.

So today we'll be talking about the future of nuclear fission and looking everything from new reactor designs to applications

in space and in other areas like medicine and agriculture, and even portable devices.

As a quick side note, today marks the sixth anniversary of our very first episode, Megastructures

in Space, and we'll commemorate that briefly at the end of the episode, and it's appropriate

for our topic today as power and energy production are so vital to our grand end of the episode, and it's appropriate for our topic today as power

and energy production are so vital to our grand dreams for the future, and as we'll see today,

fission is likely to play an enormous role in taking us into that future, especially for

the spacecraft that will actually take us there.

The elephant in the room for nuclear power is always the concerns about safety, and I tend

to think a fair amount of that is simply from nuclear power and radiation being a bit mysterious.

I don't want to dwell too much on the safety concerns or particle physics today, but we will

spend some time on them before getting the various reactor designs and future uses, and we'll

start with the basics of fission and fusion.

In nature, atoms tend to form to two categories, those that were around from the beginning,

mostly hydrogen helium, and those made by stars.

However, it is inaccurate to think most elements are made by giant stars exploding.

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