Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Thoughts on causation



The question raised by Dawey and John (see below) prompted
me to speculate. Why should the effect of comparing two
distances (on my retina) depend on explanations of things?
That comes when we study relations between quantities, not
when we measure them one by one.

I think that measuring a distance is REAL as long as I have
a tape or yardstick, (or a protractor, if triangulation is involved).
These instruments are so simple that nobody questions the
results, except for the accuracy. Naturally, the brain and retina
are involved. We do not understand everything about these
biological components but we, in physics, are not bothered
by this. Using brains and retinas does not mean that we are
imagining things. We believe measurements are REAL.

Sometimes a sophisticated set up, such as an interferometer,
is used, instead of a simple tape or ruler. Or a spectrometer
to measure the magnitude of red shift. Or an atomic clock
instead of a simple pendulum. We do not understand our
brains and retinas but we do understand how the added
components work.

Suppose I hire a laboratory assistant who follows instructions
without understanding optical components. To him optical
components are like retina and brain. He believes that
counting fringes, for example, is a REAL measurement of
distance. There is no conclusion; perhaps somebody can
push this line of reasoning a little further.
Ludwik Kowalski

John Denker wrote:

At 10:16 AM 10/20/00 -0600, Dewey Dykstra, Jr. wrote:

It is interesting to note that we do not really measure force. We measure
effects we claim to be caused by force (effects we explain by a construct
we call force?).

I'm not sure where this is going. This mentions only the tip of an
iceberg. Non-rhetorical questions include:
Do we really measure force?
Do we really measure mass?
Do we really measure time?
Do we really measure distance?
Do we really measure energy?
Do we really measure temperature?

In an important sense, the answer is "no" to all of the above. We measure
certain effects and claim they are explained (to some level of
approximation) by the laws of physics. We know the Way that can be walked
is not the true Way... but we can come pretty close.

OTOH, if quoted passage was supposed to mean that force-measurements are
intrinsically more arbitrary, harder to perform, or harder to interpret
than other physics measurements, the point is implausible and
unsupported. Would someone care to explain and/or elaborate?