Re: From Science New, and more

[Sean Carroll <sean@kua.net>]

James R. Cunningham wrote:

> Sean Carroll wrote:

> > True, I suppose. What they fail to mention is that 'most scientists' --
> > including, I might emphasise, the Alvarezes -- are in completely
> > unrelated fields of specialisation and know as little (or less) about
> > dinosaurs as (than) the general, non-scientifically-educated public.

> True, but then on the other hand, some in our field are not into physics
> or math and seem to have no concept of the amount of energy released.

Which is why collaboration among scientists of different fields to do 
interdisciplinary problems is important. But there is a danger in 
relying to heavily on one side of the matter. How many physicists, 
chemists, botanists, and other scientists have stumbled on something in 
their own field that just happened to relate, time-wise, to the K-T 
extinctions and lost all sense of objectivity in boldly announcing that 
they have 'explained' those extinctions?

The only way to explain a phenomenon like mass extinction is to 
understand its pattern throughout natural history, and the only way to 
understand the extinction of dinosaurs is to have a grasp of the greater 
biological, ecological, and geological picture in which dinosaurs lived, 
died and evolved. Understanding the amount of energy released by a 
bolide impact may be enough to let you create an idealised mathematical 
model *suggesting* that such an impact *might hypothetically* have 
contributed to a particular extinction, but that hypothesis then has to 
be integrated into the knowledge we already possess about various 
relevant fields: the way that dinosaurs lived, the patterns of 
extinction among dinosaurs and their contemporaries, the historical 
pattern of extinctions throughout geological time, and the observable 
statistical tendencies of evolution in various populations, among other 
things. Only then can the hypothesis be considered 'tested'. Too often 
scientists, seduced by the popularity and grand scope of the subject, 
get tunnel vision and think of just one minor aspect as if it were the 
solution to everything.

People like the Alvarezes who come in from a distant field like 
chemistry or astrophysics convinced that they have 'solved the mystery' 
are inherently at a disadvantage in this process of integration and 
testing of the hypothesis, because they have learned a different 
constellation of facts in their field than the constellation that is 
relevant to the subject. They may understand some things related to both 
their field *and* the K-T extinctions, like the concentration of 
iridium, but they also know a lot of other things that are unrelated to 
the K-T extinctions through which they are interpreting that knowledge, 
and fail to know a lot of things that *are* relevant, like the 
historical pattern of large and small extinctions throughout the Mesozoic.

People who are actively studying dinosaurs and specialise in them have a 
far greater chance of having the right toolbox, with all the relevant 
knowledge and method bearing on the problem, to make a sober, unbiased 
(or, at the least, with the type of biases that are cancelled out by the 
opposite biases of others in the field) assessment of the bolide-impact 
model in the view of *all* the relevant evidence, including especially 
the historical and ecological patterns that physical scientists are most 
likely to be completely ignorant about, and determine whether it passes 
enough tests to be a workable model of the most important aspects of the 
problem.

The statement of physicists that a bolide impact could release enough 
energy to cause extinction, coupled with the statement of geologists 
that there is a crater for such an impact at about the K-T boundary in 
age, is enough to put the bolide-impact-as-cause-of-the-K-T-extinctions 
hypothesis on the ballot, as it were, and open to serious investigation. 
It is *NOT* enough to verify the hypothesis and make it acceptable for 
use as a 'standard model' without significant challengers. That can only 
be done by bringing to bear biological, ecological, and historical 
evidence that dinosaur scientists have easy access to, but that are 
foreign and unfamiliar to astrophysicists, for example.

In point of fact, I believe this larger picture renders the 
direct-causation hypothesis rather silly and at best makes bolide 
impacts a minor contributing factor to the K-T and other mass 
extinctions. I find it hard to take such a direct causal 'explanation' 
of extinctions seriously when no one has yet produced any evidence that 
I know of that it would be possible for a planet-wide biological 
community to ever exist *without* rare quasiperiodic mass extinction 
events; why are we accepting an explanation of a phenomenon as 
'generally accepted truth' when it has not even been established that 
the phenomenon *needs* an explanation? It may very well be that trying 
to explain why a particularly large extinction took place at 65 Ma and 
not 75 or 55 Ma is barking up the wromg tree completely, tantamount to 
trying to explain why an electron jumps energy levels at one particular 
time as opposed to another: it just happens once in a while, 
statistically, and if it had happened at a different time we'd be trying 
to 'explain' why the dinosaurs all went extinct 45 million or 130 
million years ago.

Regardless, I think that the appropriate perspective leaves the 
bolide-cause hypothesis as at best one of several seriously contending 
models for what happened at the end of the Cretaceous, not yet anything 
approaching a comprehensive, widely-tested hypothesis (or a 'standard 
accepted fact', if you will), like the dinosaurian origin of birds or 
the monophyletic nature of the Dinosauria. And among the very people who 
have the broadest range of tools necessary to evaluate the hypothesis 
(dinosaur scientists) one finds the widest controversy on the topic, 
while among those likely to have tunnel-vision and proprietary interest 
in a particular ad hoc hypothesis (scientists from other fields) one 
finds the more common 'acceptance' of the hypothesis as an 'agreed 
fact'. I think this is strong evidence, if not downright proof, that the 
body of evidence supporting the hypothesis (though it may be clearly 
significant) is far less decisive than it is generally supposed, 
especially by the commercial media (who have no interest whatsoever in 
scientific rigour but will print any hypothesis eagerly as long as it's 
sensational and simplistic enough).

> > What should be relevant is what *dinosaur* scientists believe, not what some mythically monolithic 'most scientists' believe.

> Then, perhaps it would be wise for some *dinosaur* scientists to take a
> few more physics courses.  

Indeed, that's beyond dispute. I never said that strongly divergent 
specialisation was a *good* thing, just that it exists. Any attempt by a 
scientist to systematically acquaint him or herself with the basics of 
as many fields as possible is highly commendable.

> No offense intended to those who disagree
> with the asteroid concept and also have a quantitive feel for the
> energies involved.

I'm hardly untutoured in physics, not that I would say I have a direct 
intuitive feel for bolide impact energies. But I *do* have an intuitive 
feel for the pattern of speciation and extinction throughout the course 
of biological life, and I can't help but think any attempt to explain 
one specific instance (or 2 or 6 specific instances) of mass extinction 
in terms of bolide impacts while completely ignoring the probable 
continuity in large and small extinction patterns within a nonlinear, 
semifractally organised biosphere is just ramming one's head against a 
brick wall and declaring 'It will fall if only I hit enough individual 
bricks with enough brute force!' Perhaps it would be better to forget 
the physics of impulse and momentum for a moment and look for a way to 
topple the *whole* wall.

> > How could this *possibly* follow? It's based only on assumption: A
> > bolide hit 65 million years ago, therefore it probably killed the
> > dinosaurs.

> Well, as you no doubt know, that isn't the assumption the conclusion is
> based upon.

In point of fact, I *don't* know that. I saw no other evidence in that 
NYT article, which is part of my point: the media ignores what is 
significant scientifically speaking, and prints vague platitudes and 
wild speculations from scientists as gospel to be assumed. Maybe we'd 
have already had a solution to the K-T problem strong enough to be a 
standard accepted truth if not for the fact that this is the kind of 
crappy pseudo-scientific, unverifiable fluff that most people get when 
they read about 'science' in the media.



On a lighter note, in the thread 'Re: JP4 a GO!', padron@stud.nitnu.no 
wrote:

> JP2: This time they made the raptors actually eat a _lot_ of people,
> and instead of one T.rex there was two. Good old logic, 2 is better
> than 1.

Gotta agree with that logic. Compare the best scene in the 1st movie, 
Gennaro's demise, with the best in the 2nd movie, Eddie's extinction. 
Which do YOU think is grander and more wicked, a shaken-not-stirred 
spinal column or a snapped-like-a-twig one? ;)

> And as if that wasnt enough, T.rex had to go beserk around L.A.

Actually, it was San Diego. And I know I'm in the minority but I still 
love and revere that scene, though it's way too short and the end is way 
too anticlimactic. In fact, I still love both the 2nd book and the 2nd 
movie, no matter what anyone says.

> i think they'd really win the prize if they had added thousands of
> japanese people running in the streets screaming, but since this is a 
> hollywood movie the japanese was exchanged with cars crashing;)

But they *did* show a group of Japanese tourists, just before the Rex 
eats that tall whiny white dude. In fact, I've read that the one is 
shouting in Japanese, 'I left Tokyo to get AWAY from this!!' ;)

--
--Sean
http://www.livejournal.com/users/spclsd223/