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. To travel between the stars requires vast

amounts of fuel and energy, but as it turns out, the ocean of night in deep space is full of fuel,

if you can collect it along the way. Welcome back to another episode of Science and Futurism

with Isaac Arthur. Today we're diving into the realm

of interstellar proportion, exploring a concept that has captured the imaginations of science

fiction enthusiasts and space exploration enthusiasts alike for decades, the Bussard-Ramjet

Starship Drive. We'll explain what it is, why it might be broken, what are the uses it has, and what

workarounds might let us use it.

The Bucerd Ramjet is conceptually simple enough, space is full of hydrogen gas, and if you

have a fusion reactor, all that gas becomes fusion fuel for your spaceship, so you suck

it in, fuse it and blow it out the back, speeding up your

ship.

The Bucerd Ramjet or Ram Scoop is perhaps best known from the classic sci-fi novel Tau

Zero, which shows us a spaceship that gets stuck with their ram jet on and keeps accelerating

closer and closer to light speed.

This spaceship drive was designed

by physicist Robert Bucard in 1960, and it seemed the magic fix for all our spaceship

rows and the tyranny of the rocket equation. Indeed, if you've ever wondered what those big

lights or propellers on the front of the warp nacelles on the Enterprise are, they are listed as

...