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David Darling's Newsletter #36


March 6

The End of the World and Other Cheery News

The universe isn't for the faint-hearted. Space rocks, as big as mountains, fly around us at crazy speeds. Stars blow up and gamma-ray bursters go pop in various parts of the Galaxy, spraying their neighborhoods with lethal doses of radiation. And Earth's climate goes haywire from time to time. It makes you wonder how we've managed to survive as long as we have. By "we" I mean both the human race and life in general.

Despite being taken to task by one irate caller during my last appearance on Coast-to-Coast radio a few weeks ago, I'm firmly of the belief that life's been around on Planet Three for more or less 4 billion years and humans and their near ancestors for several million (not thousand as the caller insisted!). Four billion years is a pretty impressive span of time for life to have clung on, and even thrived, in spite of everything that the cosmos has thrown at us in the form of wayward asteroids, radiation bursts, ice ages, supervolcano eruptions, and goodness knows what else. Individual species, and even whole groups of species, haven't always been so lucky. Think about what happened 65 million years ago, when something very large hurtled down from the sky and, it seems, smashed into the planet somewhere off the present-day coast of Yucatan. In the aftermath of that awful impact, every remaining species of dinosaur died out, along with all the pterosaurs, mosasurs and other marine reptiles, and even the ammonites, which had survived the previous four mass extinctions. It was a biological holocaust - 85 percent of the species on Earth eradicated in the (geological) blink of an eye. And yet, amazingly, life not only soldiered on in the aftermath, it actually fluorished and prospered. What was bad news for the big reptiles was, it turned out, the best possible news for the mammals, which grew and diversified, with astonishing speed, to take over all the niches vacated by the demise of the dinosaurs and their ilk.

It's very probably true to say that we humans owe our existence to a single bolt-out-of-the-blue tens of millions of years go. If you want a glimpse of what might have evolved in our place if that fateful asteroid hadn't struck at the end of the Cretaceous, check out my speculative web page on dinosauroids.

Could it happen again? Could there be another "deep impact" event that might wipe us and many of our fellow species off the face of the Earth? Absolutely. Could it happen without warning – tomorrow or next year? Almost certainly not. In the past few years, astronomers have made tremendous strides in tracking down and plotting the movements of "near-Earth" asteroids and dead comets that pose any kind of threat to our security. Nothing as big as the miles-wide rock that slammed into Earth 65 million years ago could take us by surprise any more. We'd have many decades of warning of anything as big as that coming our way. But smaller stuff, up to several hundred meters across, is still a worry. And that brings me to 2004 VD17.

Just as seismologists have the Richter scale to measure the strength of earthquakes, astronomers have what they call the Torino scale (because it was devised in Torino, Italy) to show how serious a threat an asteroid poses to us in the foreseeable future. Here's my web page on the Torino scale.

It runs from 0 (no risk) to 10 (empty your bank account, throw a huge party, and try to hitch a ride on the next passing Vogon spaceship because the Earth is about to be trashed). Anything that ranked more than a 4 on this scale would be a definite concern. The object known as 2004 VD17 (until it's given a more memorable proper name) currently tops the list of potentially hazardous asteroids with a Torino score of – wait for it – 2! Not impressed? That's good, because a 2 means "impact very unlikely" on the T. scale. Given what astronomers presently know of VD17's orbit – and they're working to nail the orbit more precisely even as we speak – they estimate the chances of a collision with Earth as 1 in 1,600 in the year 2102 and 1 in 500,000 two years later. Personally, I'm not losing much sleep over such low odds on something happening that's still a century away. On the other hand, this thing does weigh the best part of a billion tons, so it would be a serious inconvenience if it landed in your backyard!

The popular media love to scare us with stories of imminent destruction from on high. But the truth is, we don't have much to worry about in the near term. And in the longer term – decades and centuries ahead – we'll have such good intelligence of every scrap of rock that could do us catastrophic damage that we'd have ample warning to mount projects for deflecting any would-be impactors.

The big concern right now has to be what we're doing ourselves to hasten our planet's demise – or at least the destruction of the biosphere. Thankfully, with a few notable exceptions, our leaders seem to be moving beyond the argument over whether climate change is in large measure a human effect. Even some of the oil companies, whose pressurizing of governments reminds me of past efforts by the tobacco giants to persuade us that smoking wasn't bad for our health (cough, splutter), are starting to take more of an interest in "green" projects. We'll see. With China and India about to join the economic superleague, it's going to be devilishly hard to keep the lid on greenhouse emissions, even if the US and Europe belatedly clean up their act. Indeed, there's a growing feeling in the scientific community that we may be at or very close to the tipping point at which, whatever we do, the polar ice caps will melt and raise ocean levels by many meters. A few months ago I started a news section on my web site that's given over to the environment: eco-news.

Also, you'll find new sections on health and life sciences, technology, mysteries of the past, and, my favorite, "strange" stories.

Also in the news recently, I was interested and slightly disturbed to find out that our entire space-time continuum might one day be swallowed up by a completely different universe that lives alongside ours. Theorists have often wondered whether our cosmos might be part of a giant swarm of universes - a "multiverse." But the general belief was that even if parallel universes existed, they couldn't interact. But now a new idea has come along, based on the "many worlds" interpretation of quantum mechanics, in which not only could parallel universes meddle in each others' affairs but they could do so with disastrous consequences. Read, if you dare, the terrifying details here (New Scientist).

Then, there's the matter of the "Big Rip" you should know about – another spine-chilling end-of-all-things tale from the storybook of modern science. Well, perhaps I'll save that for another time. Sleep well!

The very best to you,
David Darling