Will Humans Move to Another Planet? Hawking's Take

This article is an excerpt from the Shortform book guide to "Brief Answers to the Big Questions" by Stephen Hawking. Shortform has the world's best summaries and analyses of books you should be reading.

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When resources run out on Earth, will humans move to another planet? Should they? What did famed theoretical physicist Stephen Hawking think?

In his final book Brief Answers to the Big Questions, Stephen Hawking discusses space colonization. His conclusion was that humans need to colonize outer space because humans are running out of space on Earth, and because humans are at risk for extinction otherwise.

Here’s why Hawking said humans should colonize space.

The Future of Human Expansion

Will humans move to another planet in the future? According to Stephen Hawking, not only do we need to cultivate scientific literacy so our society can address the complex questions raised by new types of evolution, but we also need new generations of scientists and engineers to solve the technical problems of colonizing outer space.

Why We Should Colonize Space

Hawking presents two reasons to colonize outer space:

First, our species is running out of space on earth. Earth’s natural resources are limited, and we’re depleting them at an alarming rate. Hawking is all in favor of conserving natural resources by improving how we manage them, but he believes that in the long term, we’re still going to need more room for humanity to expand into.

Second, colonizing space mitigates the risk of extinction. Hawking warns that there is a significant probability that humans could go extinct on earth in the next millennium. But if we’ve colonized other planets by then, at least that wouldn’t be the end of our species.

Hawking mentions several threats that could lead to the extinction of humans on earth. Asteroid impacts have caused extinctions in the past, and Earth will eventually be hit by another large asteroid again.

(Shortform note: Statistically speaking, large asteroids impact the earth about every 50 to 60 million years. It’s been about 66 million years since the last impact, so we’re arguably due for another asteroid impact any day now.)

As Hawking points out, if an asteroid doesn’t get us, a global nuclear war could have much the same effect. For that matter, so could climate change. Hawking expresses concern that human activity may already have triggered runaway climate change: Rising carbon dioxide levels in the atmosphere cause global warming. Global warming melts the polar ice caps. The ground underneath the ice caps absorbs sunlight better than the ice did, accelerating global warming. Furthermore, global warming could lead to deforestation of some areas, reducing the planet’s capacity to sequester carbon dioxide and thus increasing the buildup of carbon dioxide, which accelerates global warming.

Connecting Resource Depletion to Risk of Extinction

Harari offers a slightly different perspective on the dangers of ecological collapse that reveals interconnectivity between the risks that Hawking discusses.

Like Hawking, Harari points out that we as a species are using up the earth’s natural resources at an alarming rate. Unlike Hawking, he conjectures that mankind will likely find a solution to resource depletion. Throughout history, as humans have used up their natural resources, they have discovered or developed new resources.

For example, the Iron Age began when cultures that lacked the copper deposits to make bronze-age tools figured out how to refine iron (iron ore is much more common on Earth than copper). Similarly, we now build airplanes out of materials like aluminum and titanium that were unknown just a few hundred years ago, and we can now generate electricity from sunlight or nuclear fission instead of fossil fuels.

That said, Harari also points out that new technology tends to benefit the rich more than the poor because the poor can’t afford to adopt it. If we reach a point where, for example, the poor increasingly suffer from lack of clean air and water, while the rich have the technology to purify their air and water, this could lead to class warfare.

The same principle would apply to climate change: If Earth’s climate becomes inhospitable to human life, the people who can afford to do so will likely construct climate-controlled dwellings and working spaces. If others are suffering from nearly unlivable environmental conditions, this would likewise contribute to class hostility.

As such, depleting Earth’s resources or incurring climate change not only pose a direct risk to the survival of mankind, but they also increase the risk of extinction through war. Thus, based on Harari’s discussion, Hawking’s risks are not separate risks, but rather facets of the same basic problem.

Harari discusses the problem without proposing a definitive solution, while Hawking asserts that colonizing outer space is the clear solution. Yet, this, too, could fit with Harari’s model: Perhaps colonizing space is how mankind will develop new resources in the next millennium.

Will Humans Move to Another Planet? Hawking’s Take