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finding stuff (was: Dry "wet" roads)



On 04/18/2003 10:31 AM, Herbert H Gottlieb wrote:
I was amazed at John Denker's response to the question
"What are mirages ?"

The actual task was harder than that.
The original question didn't mention mirages.
I'm quite sure Richard would have found the
answer on his own if it had been that simple.

On 04/18/2003 11:49 AM, John Mallinckrodt wrote:
>
> I really do think that Google is a vastly underappreciated resource.

It's tremendous.

> For instance, even if one does not realize that the underlying
> phenomenon is a mirage, one can simply go to Google and try something
> like
>
> "why does the road look wet"
>
> (with the parens to preserve the integrity of the question)
>
> http://www.google.com/search?q=%22why+does+the+road+look+wet%22
>
> or
>
> road wet "hot day"
>
> (to get at the essence of the question without limiting your results
> to those pages that phrase it in such an exact way)
>
> <http://www.google.com/search?q=%22road+looks+wet%22+%22hot+day%22>

That's all true, and serves as an instructive example
on how to use google, including strategic use of
quotes to group things.

But note that this task is right on the cusp of what's
doable and not doable with google. The queries
suggested above return only a single hit. Furthermore,
if you use the plural, the query
http://www.google.com/search?q=hot-roads+look-wet
returns no hits at all.

Note that I used hyphenation for grouping. It's
equivalent to using quotes in this case.

The lesson here is that google is very literal-minded.
It has no notion of synonyms. It doesn't even equate
singular with plural. If at first your search does
not succeed, throw in some synonyms and search again.
Google has an "OR" operator that comes in handy.

==================

There's another lesson hiding in here: It is important
to be able to answer ill-posed questions. The original
question was
> Why does a road appear wet on a hot day?

but if you're trying to form a mirage,
-- the fact that the day is hot is neither necessary
nor sufficient. A swelteringly hot overcast day will
not form mirages. A cold but sunny winter day will.
-- having a road is neither necessary nor sufficient.
The most impressive mirages are seen in the open
desert.

So there is no perfect answer to the question as
stated!

This is a horrible problem with the end-of-chapter
exercise questions in typical textbooks. The questions
are too perfect. They were cooked up _a posteriori_
to fit a preconceived answer.

Real-world questions are underspecified, self-contradictory,
or both.

We need to teach people to answer questions based on
the preponderance of the evidence, not just on perfect
evidence.

For more on this, see
http://www.monmouth.com/~jsd/physics/ill-posed.htm

==================

Returning to the previous point: If you are having a
hard time googling something, be alert to the possibility
that your question embodies a misconception.

If you're lucky, it is such a common misconception that
it will be explicitly refuted somewhere. Your search
find the refutation, and you will be steered back onto
the straight-and-narrow.

But if it's an uncommon misconception, the search will
fail. Example: If you want to know the resonant frequency
of the gravitational field, you will get no hits from
http://www.google.com/search?q=resonant-frequency-of-the-gravitational-field
It's such a strange misconception that nobody (until
now :-) has bothered to discuss it.

Or, what's worse, you could get trapped in the microcosm
of people who have the same misconception. Example:
http://www.google.com/search?q=astrology
returns 3 million hits. Probably less than 1% of them
are skeptical.
http://www.google.com/search?q=astrology+skeptic+OR+skeptical

==================

But the real answer to Herb's question is that I grew
up in the Southwest US. Lots of sun. Lots of open
spaces. The word "mirage" was in my vocabulary by the
time I was six.

I suspect Herb is a city boy, which puts him at a
disadvantage in this case.