These doomsday warriors look no more like soldiers than the soldiers of the Second World War looked like conquistadors.  The more expert they become the more they look like lab assistants in small colleges.

- Alistair Cooke
 

Source: Andy Nickless www.bestphotos.co.uk

by Jim Holt

Do you ever lie awake at night wondering why you happen to be alive just now?  Why it should be that your own particular bit of self-consciousness popped into existence in the twentieth century and not, say, during the reign of the Antonines or 10 million years hence?  If you do, and your musings take a sufficiently rigorous form, you might arrive at a terrible realisation: The human race is doomed to die out - and quickly.

So, at least, a handful of cosmologists and philosophers have concluded.  Their reasoning is known as the Doomsday Argument.  It goes like this: Suppose humanity were to have a happier fate, surviving thousands or millions of years into the future.  And why not?  The sun still has half its 10-billion-year life span to go.  The earth's population might stabilise at 15 billion or so, and our successors could even colonise other parts of the galaxy, allowing a far greater increase in their numbers.

But think what that means: Nearly every human who will ever exist will live in the distant future.  This would make us unusual in the extreme.  Assume, quite conservatively, that a billion new people will be born every decade until the sun burns out.  That makes a total of 500 quadrillion people.  At most, 40 billion people have either lived in the past or are living now.  Thus we would be among the first 0.00001 percent of all members of the human species to exist.  Are we really so special?

But suppose, contrariwise, that humanity will be wiped out imminently, that some sort of apocalypse is around the corner.  Then it is quite reasonable, statistically speaking, that our moment is the present.  After all, more than 4 billion of the 40 billion humans who have ever lived are alive today, and with no future epochs to live in, this is far and away the most likely time to exist.  Conclusion: Doom soon.

Even as transcendental a priori arguments go, this one is pretty breathtaking.  For economy of premise and extravagance of conclusion, it rivals Saint Anselm's derivation of God's existence from the idea of perfection and Donald Davidson's proof that most of what we believe must be true or else our words would not refer to the right things.

As far as anyone knows, the Doomsday Argument was first publicly broached in 1983 at a meeting of the Royal Society in London.  Its apparent author was Brandon Carter, a British astrophysicist (now living in France) famous for his work on black holes.  A decade earlier, Carter had baptized the much-debated anthropic principle, which purports to explain why the laws of physics look the way they do: If they were any different, life could not have emerged, and, hence, we would not be here to observe them.nbsp; We find ourselves living in this particular universe, in other words, because alternative universes are uncongenial to intelligent life.  Carter was suggesting to the Royal Society that the same goes for time: We find ourselves living in this particular epoch because earlier and later ones are, for reasons we do not fully grasp, uncongenial to us.  As interesting cosmological ideas often are, the Doomsday Argument was soon taken up by philosophers - notably John Leslie of the University of Guelph in Ontario.

Perhaps you are skeptical about, if not plain scornful of, the Doomsday Argument.  It looks like logical trumpery. How could an abstract argument have such an experientially rich upshot?  Yet it is difficult to find anything amiss in its logic.  The sole assumption it requires - an eminently plausible one - is that if humanity endures, our cumulative numbers will increase.  And the inference it makes is justified by the principle of probability known as Bayes' theorem, which dictates how a piece of evidence (we are living now) should affect the likelihoods we assign to competing hypotheses (doom sooner versus doom later).

Furthermore, the Doomsday Argument may not seem so unlikely once you consider all the forms doom could actually take.  Don't think Ebola, greenhouse, nukes - think cosmos.  An asteroid might bump into our planet (one wonders whether the Doomsday Argument occurred to the dinosaurs 65 million years ago).  The Swift-Tuttle comet - dubbed the "Doomsday Rock" by the media - will be swinging awfully close on or about 14 August 2126.  And that's the small stuff.  The North Star could go supernova at any moment.  In fact, the dread event might already have happened, in which case the news of it is travelling earthward in the form of lethal radiation that will obliterate us upon receipt.  The most delicious scenario of all is the one in which absolutely everything gets reduced to nothingness.  Most cosmologists think the universe is no more than a tenth of the way through its historical progress from the Big Bang to the Big Crunch.  But they cannot rule out the possibility that space is "metastable," meaning that it could spontaneously slip to a lower energy level at any moment.  If this were to happen, a little bubble of "true vacuum" would appear without warning somewhere and begin to inflate at the speed of light.  Its wall would contain tremendous energy, annihilating in a stroke everything before it: entire star systems, galaxies, galactic clusters, and eventually the cosmos itself.

Now that's a speculative bubble worth worrying about.

Source: Lingua Franca Volume 7 No 8 October 1997

See also:

Ending Time - Even if an asteroid NEVER strikes the earth, I read where, because the sun is expanding and getting hotter, the oceans will boil away in less than a billion years anyway.  How much less than a billion years?...

Odds for Apocalypse put at 50-50

by Deena Beasley

Los Angeles - This is the way the world might end: a genetically engineered pathogen is released, debris from an erupting "supervolcano" blocks the sun or scientists in the biggest "bioerror" of them all accidentally trigger a matter-squeezing "big bang."  The demise of civilisation has been predicted since it began, but the odds of keeping Planet Earth alive and well are getting worse amid a break-neck pace of scientific advances, according to Martin Rees, Britain’s honorary astronomer royal.  Rees calculates that the odds of an apocalyptic disaster striking Earth have risen to about 50% from 20% 100 years ago.

The 60-year-old scientist, author of the recently published Our Final Hour, says science is advancing in a far more unpredictable and potentially dangerous pattern than ever before.  He lists as mankind’s biggest threats: nuclear terrorism, deadly engineered viruses, rogue machines and genetic engineering that could alter human character.  All of those could result from innocent error or the action of a single malevolent individual.

By 2020, an instance of bioterror or bioerror will have killed a million people, Rees contends.  "There is a growing gap between doors that are open and doors that should be open," Rees, a professor at Britain’s Cambridge University, said in an interview.  The cosmologist concedes that natural disasters have always loomed - so-called supervolanoes could explode at any time and asteroids slam into the planet, causing massive climate changes - but says the most frightening risks are probably man made.  "A hundred years ago, the nuclear threat wasn’t even predicted... but that threat still hasn’t gone away," he said.  The arms race, after all, was fuelled by science, and the field has a responsibility to inform a wide public of the risks in deciding how to apply scientific breakthroughs, he added.

Biotechnology Could Change Human Nature

"For the first time ever, human nature itself isn’t fixed.  Biotech drugs and genetic engineering are empowering individuals more than ever before," Rees said.  With rapidly advancing DNA technology, "even a single person could cause a disaster," Rees warned, noting that the United States, after the 11 September 2001 attacks and anthrax scare, is well aware of this threat.  Thousands of people have the ability to engineer viruses and bacteria to cause deadly plagues.  Even if one such "weirdo" didn’t kill many people, that type of biological terrorism would profoundly change daily life, the scientist said.

Nanotechnology - the subject of a recent Michael Crichton thriller about the havoc caused by runaway microscopic machines - is also a potent threat, he said.  If the field advances far enough, rogue self-replicating nanotechnology machines - feeding on organic material and spreading like pollen - could devastate a continent within a few days, Rees said.

The dangers of global warming are also addressed in the book, subtitled A Scientist’s Warning: How Terror, Error, and Environmental Disaster Threaten Humankind’s Future in This Century - on Earth and Beyond.  Rees does not discount the possibility of disaster caused by scientific experiments involving particle accelerators.  "Perhaps a back hole could form, and then suck in everything around it," he cautions.

So what’s to be done? Rees calls for better regulation and inspection of sensitive data and experiments.  "We need to keep track of those who have potentially lethal knowledge," he said.  He also suggested better efforts to "reduce the number of people who feel excluded or otherwise motivated to cause harm."

Source: www.tiscali.co.uk 10 June 2003 © Reuters

Who'll Be Left to Say "Sorry"?

While many of us worry whether to get fish and chips or Chinese for dinner tonight, some of the biggest brains on Earth have weightier things on their minds - like the End Of The World As We Know It.  It's a familiar scenario from science fiction.  Somewhere, probably deep in the bowels of an American military research establishment, a white-coated technician pushes the button on an experiment, and before you've managed to get to the end of this sentence the world has ended.  Oblivion.  End of story.

This time the setting is Brookhaven National Laboratory in New York, where scientists have constructed a 2.6km circular tunnel for an unprecedented experiment in nuclear physics.  About now they are accelerating gold particles to 99.995% of the speed of light and crashing them into each other.  This will create temperatures of more than a trillion degrees - 10,000 times hotter than the sun.  Under these conditions matter will "evaporate" into a soup of sub-atomic particles, replicating the conditions that occurred a millionth of a second after the formation of the universe.

It's the first time scientists have had such a powerful toy to play with, and some scientists say it's way too powerful.  Last year physicist Walter Wagner wrote a letter to Scientific American magazine, proposing that the machine could create a globe-threatening black hole.  While his calculations have been found to be faulty, he stirred up a furious debate in the scientific press, with at least two other doomsday scenarios suggested.  The one given most scientific credibility suggests the experiment could create a new type of particle dubbed a "strangelet."  This would attract normal particles and gobble them up like so many dots in a cosmic computer game.  In a twinkling of an eye the entire earth would become "strange."  What this would actually mean to us is not clear, but who wants to find out?

Mr Wagner followed up his letter by trying to stop the experiments with a federal lawsuit.  Then Britain's Sunday Times newspaper inflamed things even more by running the banner headline: "Big Bang Machine Could Destroy Earth".  Brookhaven took the threat seriously enough to set up a team of physicists to assess the risk and while the project has now been cleared, one scientist on the committee said he believed the risk, though tiny, could not be ruled out.  "The probability of something unusual happening is not zero."

Surely the very concept of risk needs reassessing when all of existence is said to be at stake.  As science gets more weird and wonderful tools, it's a question mankind should be asking.  It's not a new worry.  Edward Teller, the father of the H-bomb, stunned his colleagues in 1942 by suggesting that the colossal temperatures generated might ignite the earth's atmosphere.  Manhattan Project director Robert Oppenheimer demanded an investigation and while the report, not made public until 1973, concluded there was no danger, there was still relief all round after the first H-bomb tests.

Perhaps the last word belongs to science fiction author and futurist Arthur C Clarke.  He says we should not be too certain that catastrophic experiments have not already occurred.  Some of the vast explosions seen in space may be smart-alec alien scientists getting their comeuppance for fiddling with what they don't understand.  "They might be industrial accidents," he says.

Source: The Evening Post (Wellington, NZ) Saturday 10 June 2000

Earth Warned on "Tipping Points"

Changes to the monsoon could affect millions of people

by Alex Kirby

The world has barely begun to recognise the danger of setting off rapid and irreversible changes in some crucial natural systems, a scientist says.  Professor John Schellnhuber says the most important environmental issues for humans are among the least understood.  He told a briefing in Sweden that the Asian monsoon was one of the "tipping points" that could change very quickly.  He said a better understanding of the risks was as important as the programme to prevent collisions with asteroids.

Professor Schellnhuber is research director of the UK's Tyndall Centre for Climate Change Research.  He was speaking at the EuroScience Forum in Stockholm, at a briefing by the International Geosphere-Biosphere Programme entitled Beyond Global Warming: Where On Earth Are We Going?. Professor Schellnhuber said 12 "hotspots" had been identified so far, areas which acted like massive regulators of the Earth's environment.  If these critical regions were subjected to stress, they could trigger large-scale, rapid changes across the entire planet.  But not enough was known about them to be able to predict when the limits of tolerance were reached.  "We have so far completely underestimated the importance of these locations," he said.  "What we do know is that going beyond critical thresholds in these regions could have dramatic consequences for humans and other life forms."

One example of a hotspot was the North Atlantic current, the ocean circulation pattern responsible for bringing warmer air to northern Europe, the collapse of which could lead to a very large regional climate shift.  Others were the West Antarctic ice sheet, the Sahara desert, and the forests of the Amazon basin.  Yet another hotspot, Professor Schellnhuber said, was the Asian monsoon system.  He told BBC News Online: "Modelling has shown that if air pollution and land use change, this could alter the albedo, the reflectivity, of the land.  This in turn could weaken or even suppress the monsoon, and there is evidence that several times in the last few years it has in fact been weaker.  We're investing too much in things like improving the accuracy of our weather forecasts, while the really vital elements in the Earth's system are the unstable phenomena like the monsoon.  We should have a much better understanding of these tipping points, and we have to do everything we can to stop short of triggering these instabilities.  That means we have to know where they are, and they've been off the radar screen for far too long.  Scientists have begun to realise that change could be sudden, not gradual - in some cases it could happen within a few decades."

Antarctic ice shelf: One of the Earth's critical locations

Professor Schellnhuber urged a coordinated global effort to improve understanding and monitoring of Earth's "Achilles' heels".  He said: "Such an effort is every bit as important as NASA's valuable asteroid-spotting programme designed to protect the planet from collisions.  If we can afford to gaze up at the sky looking for asteroids, we should be able to watch our own planet with as much care."

Source: news.bbc.co.uk from BBC News Thursday 26 August 2004 © BBC MMIV

For pages on more likely natural disasters - including lightning strikes, tornados, hurricanes, volcanoes, floods, global warming and more - as well as some great satellite and tree photos, clicking the "Up" button immediately below takes you to the Table of Contents page for this Environment section.