In Interstellar the population of Earth has decreased drastically. There are ongoing efforts to simultaneous repopulate the Earth and get everybody away from Earth to somewhere more hospitable.

But how many people were actually living on Earth at the start of the movie?

I found two numbers in the movie. Early in the movie Donald speaks about his childhood and says:

But six billion people...

...just try to imagine that.

Which seems to imply that compared to the current population of Earth six billion people is an unimaginably large number. (I am guessing Donald uses the redefined billion of 10⁹ and not the original definition of the word meaning one million squared.)

Later in the movie during the discussion about which planet to visit first Cooper says:

I am thinking about my family and millions of other families, okay?

Which implies at least 2 million families. And given the effort to repopulate the Earth. I would assume an average family consists of at least 5 persons.

From that I get that the population is at least 10 million people and not even close to 6 billion people. Is there any other information in the movie or other official sources which can narrow the population size down further than this?

  • I'd say that the "redefined" version has long since superceded the original meaning of billion, so it's likely you'll find only historical texts that use the outdated meaning. – Kyle Kanos Apr 10 '16 at 21:41
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    @KyleKanos There are multiple languages which did not adopt the redefined version. And in British it remains ambiguous to this date. I personally try to avoid that word in order to avoid ambiguity. But in this particular case I was citing somebody else using the word. – kasperd Apr 10 '16 at 21:57
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    @Lightness: I'd argue it's the scientific version. – Kyle Kanos Apr 10 '16 at 22:13
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    Heh, apparently the standards bodies have deliberately avoided settling on this, instead sticking with the SI prefixes and dumping ambiguous ways of saying the same thing. Probably wise. – Lightness Races in Orbit Apr 10 '16 at 22:20
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    @kasperd - I don't know anyone that still refers to the English billion. Pretty much everyone in the UK uses the US version. – Valorum Apr 12 '16 at 7:34

We don't know. It isn't explictly stated in the 2011 film script, nor the 2008 first draft script, nor the tie-in novelisation what the remaining population of Earth is. For that we have to turn to the accompanying book "The Science of Interstellar" written by the film's Science Advisor, Kip Thorne.

In 2007, when Jonathan (Jonah) Nolan joined Interstellar as screenwriter, he set the movie in an era when human civilization is a pale remnant of today’s and is being dealt a final blow by blight. Later, when Jonah’s brother Christopher Nolan took over as director, he embraced this idea.


Some combination of catastrophes has reduced the population of North America tenfold or more, and similarly on all other continents. We have become a largely agrarian society, struggling to feed and shelter ourselves. But ours is not a dystopia. Life is still tolerable and in some ways pleasant, with little amenities such as baseball continuing. However, we no longer think big. We no longer aspire to great things. We aspire to little more than just keeping life going.

So there you have it. The film's script advisor was operating on the principle that the population of the US was something like 30 million and the population of the whole world is perhaps 500-600 million.

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