Re: Galileo -- overrated?

First of all, "overrated" is a broad enough term that infinite fights are
available over it. (Hoping that's not your actual intent.) Suppose, for
instance, that the one claim you mention below were to be refuted; that
would have no effect whatever on other matters, like a few fundamental
ideas in physics, discoveries in astronomy, the use of experiment in
conjunction with mathematical analysis, yada yada, not to mention the
little face-off with the Holy Inquisition -- on all of which, there is
debate on whether he's overrated, or deserves any credit at all, or was a
charlatan and/or a fool.

[BTW, short of making him a Holy Sainted Martyr to freedom of inquiry, or
giving him credit for things he didn't claim it for, he's not overrated.
In case anyone was wondering :-]

Anyway --

On Sat, 28 Jul 2007 10:22:53 UTC, Hugh Newbury <hugh@xxxxxxxxxxxxxxxxxxxx>
wrote:

...
It has been said that Galileo invented the telescope.

I wonder who ever said that? Not anyone who had a claim to knowing
anything. After all, Galileo himself disclaimed credit for the original
invention in the very first thing that he (or perhaps *anyone*) published
about the use of the telescope. Not that you couldn't get the opposite
impression from some sources; it just shows the need to know your sources.

... But the device that
is nearly always said to be due to Galileo is the pendulum. He watched
the swinging lamps in Pisa cathedral and saw thay were keeping the same
time day after day.

I have had doubts about this, not that the story about Pisa cathedral is
wrong, but that he was the first to notice the phenomenon. It is
inconceivable that the ancient Greeks did not notice the same thing.

Actually, there's plenty of skepticism about the Pisa story -- probably
about as much as there is concerning the balls dropped from the Leaning
Tower. Another suggestion is that he noticed the effect when experimenting
on the effects of tension on strings, at the time his father observed the
relation between tension and pitch (prossibly the first non-linear
physical law ever discovered). Of course, the origin doesn't matter much
anyway.

The place where history comes in, though, is the "inconceivable" bit. In
two thousand years -- or 4,000 since the Egyptians might have noticed it
-- it also seems inconceivable that people, knowing about it, would never
have written a word about it! And yet, that _seems_ to be the case.

BTW, did you know that the Chinese invented gimbals in the Tang Dynasty?
(9th century or thereabouts, centuries before Europeans) Used the device
for carrying lamps, ingeniously keeping the lamp level; don't seem to have
noticed its advantages with their other little invention of the compass.
Anyway, certainly they knew something about swinging lamps, and it would
not surprise me to find that someone had observed the (near-) constancy of
period. But there doesn't seem to be a record of it.

We know for sure that Galileo's contemporaries found the discovery
newsworthy; we also know that they had a thorough grounding in the Greek
classics.

Actually the failure of the Greeks to observe and discuss a mere
quantitative physical law with no theoretical importance -- by their
standards -- is less surprising to me. More surprising, in fact, that the
Arabs didn't pick it up.

They noticed so much else of the world's phenomena, including such as
the tension and length of a string producing varying notes and how to
make it sound harmonics.

In fact they did not know the quantitative relation of pitch to tension;
only to length with tension constant. The law had to wait for Vincenzio
Galilei, see above.


Others, the Arabs and earlier the Babylonians,
were ingenious innovators. Leonardo tried to make timepieces, or at any
rate design them. Did none of these people see the connection between a
swinging weight and timekeeping?

Well, coming up to the time of Leonardo et al., it seems clear that they
did not. There are lots of records from that time, and there were lots of
mechanical clocks of pretty crummy accuracy. The lack of any record of the
effect at least makes it clear that this was a long way from common
knowledge! Absence of evidence is, of course, evidence of absence; one
just needs to apply Bayes' Theorem properly.

Speaking of timing of observations, the hypothesized use of a pendulum (I
have unfornately snipped the text here) might not have been such a good
idea as you suppose. When Galileo himself wanted to measure time
accurately, he seems at one point to have used music -- musicians have
remarkable abilities at keeping accurate time and subdividing it -- but
definitely used dripping water as his timepiece later. No pendula. To be
sure, he wanted accurate measurements of periods of a few seconds, and no
simple pendulum arrangement is very good for that.
...
Later in the 17th century Christian Huygens and a clockmaker made a
clock governed by a pendulum.

This was only a few years after Galileo drew up a plan for a pendulum
clock; but Huyghens really made one, and it worked, and he deserves full
credit for it.


...

What do you think? Overrated or not?

Frankly, I think your estimate of the force of must-have-been and the
argument from personal incredulity is overrated. I repeat, however, that
it would not surprise me at all if some obscure (to us) Chinese or Arabic
source made a mention of the effect; it would not be a really _big_
surprise if it showed up in Roman or Greek or Hindu or Mayan sources. At
that point, we could _begin_ the debate over how to allocate the credit
for this obscure effect, suddenly brought to prominence at the time of the
Scientific Revolution (which so many true experts know didn't really
happen).


--
Dan Drake
dd@xxxxxxxxxxxx
http://www.dandrake.com/
porlockjr.blogspot.com
.

Relevant Pages

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