Re: XP Requirement Analysis?

From: Dagfinn Reiersol (reiersol_at_online.no)
Date: 10/06/04 

Date: Wed, 06 Oct 2004 09:04:53 +0200

Cristiano Sadun wrote:
> Dagfinn Reiersol <reiersol@online.no> wrote in news:xDt8d.235$Km6.5066
> @news4.e.nsc.no:
>
>
>>Cristiano Sadun wrote:
>>
>>>Dagfinn Reiersol <reiersol@online.no> wrote in news:_C78d.18$Km6.383
>>>@news4.e.nsc.no:
>>>
>>>
>>>
>>>>I know saying that heavier objects fall faster is an simplistic way of
>>>>putting it.
>>>
>>>
>>>Not simplistic - wrong. As much as saying that the earth is flat (and
>>>noting that occasionally it may seem flat).
>>
>>Since you're not giving any reasons, I'm unable to guess what your
>>disagreement is.
>
>
> The reasons are the only ones which hold for any physics statement: there
> is at least a set of repeatable experiments that proves your statement
> false. Btw, these experiments were run by Galileo about 400 years ago.
>
> The example I provided is similar in nature: if you walk for three paces
> (or thirty) you might think the earth is - indeed - flat. Now, how would
> you react if someone was telling nowadays that "the earth is flat"?
> Following with "it's a simplistic way of putting it"?
>
> There's nothing simplistic about it: it's just wrong. In the same way
> that "heavier objects fall faster" is wrong.
>
> As an old professor of mine would put it, if it isn't clear yet, the
> pharmacy faculty's always open :-)
>
>
>>Let me try a less simplistic generalization: In air,
>>heavier objects fall faster unless they are *either* larger and
>>(sufficiently) less dense *or* have a shape that causes greater drag
>>*or* both.
>
>
> Fine. That's not the same statement as above, and I don't have any
> problem with it. Similarly, I wouldn't have any problem with a statement
> saying that the earth is locally flat.
>
>
>>You either 1) disagree with this statement or 2) you think that going
>>from that statement to "heavier objects fall faster" is wrong rather
>>than simplistic.
>
>
> 2). It's not a simplification, but a distortion so heavy that misleads
> the reader. The boundary conditions are essential to proper divulgation,
> in that case.
>
> (Imagine someone who doesn't know physics: if nobody objected to your
> statement, he would go on thinking that, indeed, heavier object do
> _generally_ fail faster. It isn't immediate or natural to think of the
> air drag and the object geometry).
>
>
>>If 1), you might want to go over the maths in my earlier post and tell
>>me where the problem lies. If 2), I would say we have a trivial
>>disagreement over words that's not worth pursuing further.
>
>
> As you like, of course. But keep in mind that general statements are very
> powerful, and science is all about getting them right.
>

Or you could say that science is all about exploring the unknown. It
depends on your perspective and your values, and I think that's the
underlying difference between our positions. How important is it to be
right? How "real" are the observations of everyday life compared to
scientific theories?

I'm deliberately taking the statement about heavy and light objects at
face value. I understand you as saying that's inappropriate, that I need
to take the context into account by considering my statement in the
light of how a reader might interpret it and in the light of current
physical theory.

And I might agree with you if the situation were different. But I'm
giving myself permission--in this particular context--to take the
statement as literally as possible and explore where that leads me. And
what triggered that originally was Uncle Bob's statement that it took
2500 years to discover that heavy objects don't fall faster. In other
words, the original context was a different one. I was trying to see how
it must have seemed during those 2500 years rather than being arrogant
on behalf of the present.

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