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 ad-free, plus hours of bonus content.

Check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

Good afternoon, everyone, and welcome to Science and Futures and with Isaac

Althor's monthly live stream Q&A. As usual, we'll be taking your questions live from the

audience as given to us by our moderators and by my lovely wife and assistant, Sarah.

Before we get started, I just want to give everyone the quick announcement that we are probably going to be skipping the Thanksgiving live stream at this point in time.

That's kind of like guess.

That's not guaranteed the moment, but we should be having this one, next one, and then on January 31st, sorry, December 31st, but at the very end of the year.

But maybe not wonderful Thanksgiving yet.

That's not quite decided. Do we have any questions to get started?

We do actually have a question from Christian Carello, Super Chat 499. Thank you, Christian.

Would an Orion Drive spaceship require large radiators like other spacecraft?

And what's the best method for decelerating and steering such a spacecraft?

For decelerating we usually assume you're going to use the exact same thing. In fact the general idea with the Orion Drive is that you might be able to accelerate using something like a beam from in system to get you up to speed and then you use the Orion

Drive to slow down is another one of our options.

Or you might use a variation of an Orion Drive that strips matter out the back from an energy

beam as opposed to having nuclear bombs on board.

But either way, you can use the nuclear bombs pushing the ship to slow down to or to steer

it.

In terms of actually changing your direction with

...