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.

Some say the world will end in fire, some say in ice.

From what I've tasted of desire, I hold with those who favor fire.

Welcome to Science and Futurism with Isaac Arthur as we celebrate our 300th episode and take a look at how the Earth might come to an end,

and we will be covering a range of options from natural to artificial, near term to far future, fiery to frozen.

There are a lot of options, and this channel is not noted for any compulsion for brevity, especially for our 300th episode special,

so we'll be here for a bit and grabbing a drink and a snack is advised. Fier and Frozen

Indians are probably the two most popular end-of-the-world scenarios for contemplation,

and we open the episode of the quotation from famous poet Robert Frost's classic,

Fire and Ice, and for anyone who's curious,

Robert Frost is my favorite poet, and Fire and Ice is one of my favorites by him. There's two

reported inspirations for the poem, one being Dante's Inferno, and the other being a conversation

Frost had with an astronomer about the sun exploding or extinguishing. Now that poem was written

back in 1920, and a popular notion for the fate of stars at the time was that they were hot

for the same reason planetary cores are hot, they heated under immense gravity of their

own formation and have been slowly cooling. Such being the case, stars would die off by slowly

cooling and dimming and words about them

by freezing. Another notion that sometimes made the rounds was that there was a limit how

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