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.t.v.t.v. And use my code, Isaac Arthur.

This episode is brought to you by Brilliant.

I heard some scientists were surprised when they discovered a particle that moves faster than

the speed of light.

I guess they just didn't see it coming.

We occasionally talk about what faster light or FTR Traveler Communication might imply

for exploring the universe, but mostly on this show, unlike virtually every science fiction

setting, we take the stance that light speed is a hard limit, something you can't even reach

for the spaceship let alone exceed.

Folks often ask me to discuss why this is the case or what it would mean if it weren't,

and if we would do some episodes on it.

In point of fact, we did.

Our FTR series was one of our first on the show and I rarely mention them because production

wise they are early episodes in show, and folks have been asking for it

to be replaced or expanded on for a long while now, and we'll go ahead and do that,

but I thought we'd reopen the topic by discussing why it's problematic to reach or exceed

light speed and overviewing some of the suggested workarounds and what they require of reality.

As an example, and one we'll get to in more detail later today, most versions of warp drives

or wormholes require negative matter or negative energy to operate, that's baked into the

...