Bad news - we are way past our 'extinct by' date

[Michael Stuart Kelly]

Bad news - we are way past our 'extinct by' date

Robin McKie, science editor

March 13, 2005

The Observer

OK. I am trying to give a hearing to all sides on some of these issues, but this article from a couple of years ago goes too far. Forget about global warming. We can be afraid for real. Or was this just the fearmongers exercising their chops? From the article:

After analysing the eradication of millions of ancient species, scientists have found that a mass extinction is due any moment now.

Their research has shown that every 62 million years - plus or minus 3m years - creatures are wiped from the planet's surface in massive numbers.

And given that the last great extinction occurred 65m years ago, when dinosaurs and thousands of other creatures abruptly disappeared, the study suggests humanity faces a fairly pressing danger. Even worse, scientists have no idea about its source.

If I understand this correctly, reality is not conforming to the figures. And the whole crisis is nothing but figures.

Maybe we should talk to our politicians and make the facts fit the figures and blow the hell out of everything? That way our scientists will not suffer a credibility gap...

Michael

[Brant Gaede]

Bad news - we are way past our 'extinct by' date

Robin McKie, science editor

March 13, 2005

The Observer

OK. I am trying to give a hearing to all sides on some of these issues, but this article from a couple of years ago goes too far. Forget about global warming. We can be afraid for real. Or was this just the fearmongers exercising their chops? From the article:

After analysing the eradication of millions of ancient species, scientists have found that a mass extinction is due any moment now.

Their research has shown that every 62 million years - plus or minus 3m years - creatures are wiped from the planet's surface in massive numbers.

And given that the last great extinction occurred 65m years ago, when dinosaurs and thousands of other creatures abruptly disappeared, the study suggests humanity faces a fairly pressing danger. Even worse, scientists have no idea about its source.

If I understand this correctly, reality is not conforming to the figures. And the whole crisis is nothing but figures.

Maybe we should talk to our politicians and make the facts fit the figures and blow the hell out of everything? That way our scientists will not suffer a credibility gap...

Michael

A small comet is headed at Chicago. That's all I know. Have a drink and a cigar.

--Brant

[Laure]

Also, you might want to lie down and put a bag over your head, a la Hitchhiker's Guide...

[Wrighty]

So what happened 124 million (+ or - 6 million) years ago? Or 186 million or 248 million years ago????

Is the impending collision of scientists and statisticians to be the apocalyptic event?

Have you heard its in the stars....next July we collide with Mars......

[John Dailey]

~ Where's Bruce Willis when ya need him?

~ Wait a minute! Morgan Freeman isn't our President! Ah-h-h, you must've already had that drink (sure that's a cigar?)

LLAP

J:D

[Greybird]

"The crash of the whole solar and stellar systems could only kill you once." ~ Thomas Carlyle

[Dragonfly]

Well, it's not quite nonsense. The impact of an asteroid could wipe out our civilization. The odds that it will happen in the near future are very small, but as the result would be so disastrous it's useful to do something about it, like studying all the objects that might cross the orbit of the earth and looking for methods to change the orbit of the potential killer slightly so that it will miss the Earth. But even smaller objects can be disastrous: think of the Tunguska event in 1908, and what would have happened if that comet or what it was had exploded over a densely populated area. There would be nothing left of New York for example. Après nous le déluge?

[Brant Gaede]

Well, it's not quite nonsense. The impact of an asteroid could wipe out our civilization. The odds that it will happen in the near future are very small, but as the result would be so disastrous it's useful to do something about it, like studying all the objects that might cross the orbit of the earth and looking for methods to change the orbit of the potential killer slightly so that it will miss the Earth. But even smaller objects can be disastrous: think of the Tunguska event in 1908, and what would have happened if that comet or what it was had exploded over a densely populated area. There would be nothing left of New York for example. Après nous le déluge?

It looks like they are going to shut down that giant observatory in Puerto Rico which is useful in finding and tracking asteroids.

--Brant

[Robert Campbell]

Michael,

Our planet has gone through some mass extinctions caused by big meteorites or asteroids. The theory is now generally accepted that dinosaurs became extinct 65 million years ago after a big meteorite or small asteroid slammed into Chicxulub (in the Yucatan Peninsula). Some theories of the Permian mass extinction (251 million years ago) have an asteroid hitting the part of Siberia (south of the Taymyr Peninsula) that subsequently produced a gigantic lava flow.

Trying to make precise temporal predictions of such rare events can get pretty silly. But the danger should not be discounted.

Robert Campbell

[Michael Stuart Kelly]

Dragonfly and Robert,

I agree about the danger of asteroids. (Now there is where nuclear bombs—oodles of them—can be extremely useful.)

I don't agree about the danger of time frame. Especially since even scientists can find something recurring as a cause. That was the point of my mirth.

Michael

[Dragonfly]

Even the time frame doesn't have to be nonsense. It would be nonsense if there is a fixed (very low) probability of such an event. But there is also the possibility that the probability fluctuates with a period of about 62 million years with a sd of 3 million years, for example by some periodic passage of the solar system through a cloud of objects like asteroids. That so far no such catastrophe has happened in our "recent" history is not in contradiction with that hypothesis, as the uncertainty of a few million years is still very large compared to human time scales, so there is no reason to say that "reality is not confirming to the figures", we are certainly not "way past our 'extinct by' date". If nothing happens in 10000 years the hypothesis may still be valid. It would be wrong (still assuming that the hypothesis is valid) to conclude from the fact that for many millions of years no such big catastrophe has happened, that the probability is correspondingly low. That would only be true if the probability doesn't change with time, and it seems that there is evidence against that supposition, so the probability may in this period be much higher. Now the probability for such an event happening within a year is still very low, but not as low as you might expect from the frequency of those events alone.

[PalePower]

Ever since I took Geometry I can't stop pinpointing instances of inductive as opposed to deductive logic.

Inductive logic is a process of arriving at a conclusion based on "what has happened before" - it includes assumptions to be made alongside of the starting premises. As such, it can be flawed. For example, you're standing in line at a movie theater, and all the people that have gone before you pay $6.50 for their ticket; therefore, you conclude that your own ticket will cost $6.50. It's logical to think this, but it's also not definite - say everyone else paid for a matinee movie and you're going to a later one, so your ticket will cost more.

Deductive logic is a process of arriving at a conclusion held strictly within the starting premises; deductive logic cannot be flawed. For example, at the movie theatre box office, you conclude that your ticket will cost $6.50 because there's a big honker of a sign up front that says, "ALL TICKETS COST $6.50."

...

I think that this "impending extinction" hype would be a salient example of inductive logic.

But, just in conclusion, lemme get this straight: scientists are freaked out because humans are "due" for extinction ...JUST because "something" like this has happened before?

So we should be scared?

Even though. . . since we don't know the cause. . . we really don't know what we should be scared OF.

... *facepalm*

Call me when the world ends, I'll be practicing piano.

~Elizabeth

[Chris Grieb]

Elizabeth; You have the right attitude! Thank you!

[BaalChatzaf]

I agree about the danger of asteroids. (Now there is where nuclear bombs—oodles of them—can be extremely useful.)

Not necessarily. A large asteroid might not be solid, but a lose conglomeration of rocks. In that case nuking the thing will not change its course. It will mean a lot of smaller rocks hitting the earth and probably causing more damage.

The best survival strategy would be to build a large habitat off planet. If the Earth is badly damaged the folks on the habitat could survive and come back down when things are settled.

Ba'al Chatzaf

[Michael Stuart Kelly]

Bob,

You mean a lot of little rocks would not disintegrate from friction in the atmosphere on the way down?

Michael

[BaalChatzaf]

Bob,

You mean a lot of little rocks would not disintegrate from friction in the atmosphere on the way down?

Michael

Little compared to the original body. Rocks the size of sand grains or pebbles burn up. Rocks weighing hundreds of pounds make it to the ground, although part of the material is vaporized. Assume an asteroid shaped like a sphere and ten miles across is a loss aglomeration. Assume that an attempt to divert the asteroid breaks it into several rocks a quarter of a mile across. They are going to make to the ground. If they all land at nearly the same place they will do the same amount of damage as the original body. Even if they are scattered they will create fires and shock waves that will do much damage. The key to the thing is velocity. The kinetic energy contain in a mass m moving at velocity v is 1/2*m*v^2. If you break up m into smaller masses (but not too small) the total amount of energy when the stuff hits the ground is still dominated by v.

Diversion of an incoming comet or asteroid by a nuclear blast will work if the body is solid and it is diverted at a great enough distance. But suppose the body is not solid. Bad news.

Ba'al Chatzaf.

[Richard Uhler]

'''

Diversion of an incoming comet or asteroid by a nuclear blast will work if the body is solid and it is diverted at a great enough distance. But suppose the body is not solid. Bad news.

On that general topic, perhaps you've heard about this in the past week:

http://www.guardian.co.uk/science/story/0,,2083785,00.html

Edited May 27, 2007 by Richard Uhler

[Brant Gaede]

Bob,

You mean a lot of little rocks would not disintegrate from friction in the atmosphere on the way down?

Michael

Little compared to the original body. Rocks the size of sand grains or pebbles burn up. Rocks weighing hundreds of pounds make it to the ground, although part of the material is vaporized. Assume an asteroid shaped like a sphere and ten miles across is a loss aglomeration. Assume that an attempt to divert the asteroid breaks it into several rocks a quarter of a mile across. They are going to make to the ground. If they all land at nearly the same place they will do the same amount of damage as the original body. Even if they are scattered they will create fires and shock waves that will do much damage. The key to the thing is velocity. The kinetic energy contain in a mass m moving at velocity v is 1/2*m*v^2. If you break up m into smaller masses (but not too small) the total amount of energy when the stuff hits the ground is still dominated by v.

Diversion of an incoming comet or asteroid by a nuclear blast will work if the body is solid and it is diverted at a great enough distance. But suppose the body is not solid. Bad news.

Ba'al Chatzaf.

There's hope to divert an asteroid, but a comet? Forget it.

--Brant

[John Dailey]

~ As with determining the 'probability' of sapient life existing elsewhere, since any factors of a known type are not themselves quantifiable other than being educated/estimated (subjectively preferenced?) guesses, the 'probability' of a dangerously 'large-enough' asteroid hitting the earth is as accurate a one as a horosocope's prognostication. The danger IS there, no question; but what the level of its risk is, is a question we really have no basis for any rational answer about...beyond guessing. Any worrying about it sounds like a GW-type subject. Concern, yes, for an EWS satellite set up; but now, worry? Nope. --- Besides, Bruce Willis is busy with other things right now.

LLAP

J:D