[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Lost World physics (SPOILER)



> I'm not so sure about Ian's application of the Heisenberg principle. Ian
> states that trying to observe  (study) a system changes the system. This
> does not scale up well from the subatomic. He was talking in the context
> of studying the dinos, and I would maintain that a lot of study could be
> done WITHOUT changing the system. Hammond's people were observing the island
> with satellite derived infrared images; in no way could this ever change
> or disturb the system(s) there.

  Whee, at last a thread in which a used physicist like yours truly
doesn't feel too embarrassed to say something, not that that usually
stops me...

  I think that just about everybody who has posted on this thread is
correct.  On the one hand, the Heisenberg uncertainty prinicple is
about as solidly established as anything in physics.  It is wrapped up
in quantum mechanics in a fundamental way, so much so that people who
do physics on a scale where quantum effects are large and commonplace,
don't even talk about the uncertainty principle _per_se_ any more:
They are all used to calculating probabilities from square one, and
think in that kind of language all along.  Quantum mechanics has
vastly changed physicists' perception of what the strange beast we
name "reality", truly is.

  On the other hand, it is also true that for most macroscopic systems
-- be they pianos or pachycephalosauri -- uncertainties rooted in
quantum mechanics are usually not readily apparent.  They are there --
quantum mechanics does apply to pianos! -- but you usually have to do
lots of looking and thinking to ferret them out.  And they are often
swamped by diverse other sources of uncertainty, such as more
conventional error or incompleteness in measurement or understanding.

  Yet on the gripping hand, as science-fiction authors Larry Niven and
Jerry Pournelle have put it, the rigorous and unavoidable uncertainty
of quantum mechanics has begun to provide a powerful and useful
metaphor for diverse uncertainties in everyday life.  And it surely
appears that field ethologists have frequent grave difficulty
performing observations without changing the system observed.

  I think of Del Owens, in _Cry_of_the_Kalihari_, carefully attempting
to carry out the non-interventionist protocols she had been taught, as
she tried to study a brown hyena from a distance: She did not quite
know what to do when it noticed her presence, walked up to her, and
started sniffing her hair.

  Or, in a more personal ancedote, I was once on a whale-watch trip in
Monterey Bay.  Our skipper scrupulously attempted to respect the
Marine Mammal Protection Act, and give all the big cetaceans at least
100 meters of clearance.  Yet his actions were no deterrent to the
Orca pod that wondered what we looked like at five yards' range, and
approached to find out.

  Thus non-intervention appears not to be a simple declaration;
rather, it is a bilateral treaty.  If all parties do not sign, it may
not work quite the way its human creators anticipate.


                                        --  Jay Freeman