Scientific American - Lights Out: How It All Ends

How It All Ends.

From the Editors of Scientific American
Letters to the Editor
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Published by Scientific American
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ISBN: 978-1-466824195

Introduction: The Four Horsemen

The four horsemen of the apocalypse are traditionally war, famine, plague and death; or in older versions, war, famine, death and a figure often presented as conquest. Some would call death a bit redundant since war and famine often get you there in any case. But eschatology has never been entirely consistent, and it needn't be.

Classical authors were familiar with only four horsemen, but modern ones could add environmental devastation and nearby supernovas. This book is a compilation of such end of the world scenariosor at least, things that could make human life really difficult. Some are apocalyptic, others less so, but they show that even if one isn't taking the Book of Revelation or the supposed Mayan prophecy as a template, thinking about it is fascinatingand sobering.

Some endings only affect humansmass starvation for us isn't likely to bother rats. Plagues have often decimated one groupthe Native Americans come to mindwhile leaving others intact. Meanwhile, with the invention of nuclear weapons, a war that eliminates human life on Earth is still a very real possibility.

Then there are cosmic-scale catastrophes that could profoundly change life on Earth. Meteor strikes, nearby gamma-ray bursts, and supernovae, all have the very real possibility, however remote, of sterilizing the planet.

And some scenarios are simply inevitable. The universe is expanding, and there's no sign it will stop. Eventually, the temperature will drop, protons will decay, and atoms could be torn apart. Unless our distant descendants find another universe to live in, prospects look pretty grim. The physical impossibility of eternal life is likely to disappoint some, but one might as well ask if it's not better to know that yes, we really are all headed to the same place.

After all, we all know the world will end, just as we know we will die. We can't predict the date of our individual deaths, but we can say that the laws of physics, chemistry and biology dictate certain outcomes for the species, planets, stars, and universe.

The ability to map out the end also grants us the power to avert it, at least in some cases. Included in this book is a seminal piece outlining the possibility of nuclear winter. Former Soviet leader Mikhail Gorbachev has stated that such studies underscored the fact that nuclear war was unacceptable, and were a major impetus for him to seek to reduce tensions with the United States. As a species we've tackled ozone depletion, and there's no reason other environmental problems can't be dealt with as well. The same technologies that allow us to destroy cities on the other side of the planet can stop an asteroid from visiting on humans the fate of the dinosaurs. The question was never technical ability, only political will.

So while much of this book might seem a gloomy exercise, there's an optimistic side too: we may not endure eternally, but stupidity or hubris doesn't have to end our world prematurely.

-Jesse Emspak
Book Editor

Laying Odds On The Apocalypse

by John Matson and John Pavlus

With all due respect to T. S. Eliot, maybe the world really does end with a bang, not a whimper. Whether of our own creation (nuclear holocaust) or of natures (asteroid impact), plenty of cataclysms could doom civilizationperhaps even putting the survival of the species in jeopardy. We assessed the likelihood of several doomsday scenarios, from oft-discussed threats such as climate change to more fanciful ideas such as quantum fluctuations that would destroy our universe. The probabilities listed here are not scientific factan impossible goal when estimating the possibility of unprecedented eventsbut informed conjecture based on researchers expert opinions. We also relied on those opinions to approximate how catastrophic each event would be, ranging from 1 (localized chaos) to 10 (good-bye, universe).

KILLER PANDEMIC
One in 2 in the next 30 years
Destruction Ranking: 4
Humankind is more vulnerable than ever to a devastating, Black Deathstyle pandemic, says Joseph Fair, director of global field operations for the Global Viral Forecasting Initiative. He declined to predict when one might strike, instead rating civilization as a lowly two on a 10-point preparedness scale. The next pandemic, Fair says, will likely be a pox or a virus that is either new to humans or a more deadly adaptation of a common virus.

SOLAR SUPERSTORM
One in 20 in the next 15 years
Destruction Ranking: 2
We dont want to be alarmist, says Daniel N. Baker, a space scientist at the University of Colorado at Boulder, but a solar eruption could grow large enough to knock out the power grids and communication systems over much of the world. If that were to occur today with our modern, highly electronically connected society, Baker says, it would undoubtedly be devastating to the most advanced countries.

RUNAWAY GLOBAL WARMING
One in 2 in the next 200 years
Destruction Ranking: 3
The ice sheets in Greenland and West Antarctica together contain enough water to raise global sea levels by about 12 meters, erasing coastal cities and making refugees of hundreds of millions of people. Without a change of behavior, humankind could set into motion the irreversible melting of both ice sheets by the end of this century, says Henry Pollack, an emeritus professor of geophysics at the University of Michigan at Ann Arbor and author of A World without Ice (Avery, 2009). My particular feeling is that itll be touch and go as to whether we can actually achieve the avoidance of Greenland and West Antarctic ice loss, Pollack says. The consequences of displacing so many peoplethe world has never dealt with something like that.