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issue is not simple). There are
more radical extensions of the idea of observation. It is commonplace in the most rarefied reaches of
experimental science to speak of `observing' what we would naively suppose to be unobservable if'
observable' really did mean, using the five senses almost unaided. Naturally if we were pre-positivist,
like Bacon, we would say, `so what?' But we still have a positivist legacy, and so we are a little startled
by routine remarks by physicists. For example, the fermions are those fundamental particles with
angular momentum such as 1/2, or 3/2, and which obey Fermi Dirac statistics: they include
electrons, nuons, neutrons, and protons, and much else, including the notorious quarks. One says
things like: `Of these fermions, only the t quark is yet unseen. The failure to observe tt' states in e+e-
annihilation at PETRA remains a puzzle.3
The language which has been institutionalized among particle physicists may be seen by glancing at
something as formal as a table of mesons. At the head of the April 1982 Meson Table one reads that
`quantities in italics are new or have been changed by more than one (old) standard deviation since
April 1980.4 It is not clear even how to count the kinds of mesons which are now recorded, but let us
limit ourselves to one open page (pp. 28 9) with nine mesons classified according to six different
characteristics. Of interest is the ` partial decay mode' and the fraction of decays which are quantitat-
ively recorded only when one has a statistical analysis at the 90% confidence level. Of the 31 decays
associated with these nine mesons, we have 11 quantities or upper bounds, one entry `large', one entry
`dominant', one entry `dominant', eight entries `seen', six entries `seen', and three `possibly seen'. Dudley
Shapere has recently attempted a detailed analysis of such discourses He takes his example from talk
of observing the interior of the sun, or another star, by collecting neutrinos in large quantities of
cleaning fluid, and deducing various properties of the inside of the sun. Clearly this involves several
layers, undreamt of by Bacon, of Bacon's idea of `making manifest, things not directly perceptible, by
means of others which are'. The trouble is that the physicist still calls this
((footnote:))
3 C.Y. Prescott, `Prospects for polarized electrons at high energies', Stanford Linear Accelerator, SLAG-PUB-263o, October 1980, p. 5. (This is a report
connected with the experiment described in Chapter 16 below.)
4 Particle Properties Data Booklet, April 1982, p. 24. (Available from Lawrence Berkeley Laboratory and CERN. Cf. `Review of physical properties', Physics
Letters 111B (1982).)
5 D. Shapere, `The concept of observation in science and philosophy', Philosophy of Science 49
(1982), pp. 231-67.
vation
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'direct observation'. Shapere has many quotations like these: 'There is no way known other than by
neutrinos to see into a stellar interior.' 'Neutrinos,' writes another author, `present the only way of
directly observing' the hot stellar core.
Shapere concludes that this usage is apt and analyses it as follows: 'x is directly observed if (I)
information is received by an appropriate receptor and (2) that information is transmitted directly, i.e.
without interference, to the receptor from the entity x (which is the source of the information.)' I
suspect that the usage of some physicists illustrated by my quark quotation above is even more
liberal than this, but clearly Shapere gives the beginnings of a correct analysis.'
Shapere notes that whether or not something is directly observable depends upon the current state of
knowledge. Our theories of the workings of receptors, or of the transmission of information by
neutrinos, all assume massive amounts of theory. So we might think t hat, as theory becomes taken
for granted, we extend the realm of what we call observation. Yet we must never fall prey to the fallacy
of talking about theory without making distinctions.
For example, there is an excellent reason for speaking of observation in connection with neutrinos
and the sun. The theory of the neutrino and its interactions is almost completely in-dependent of
speculations about the core of the sun. It is precisely the disunity of science that allows us to observe
(deploying one massive batch of theoretical assumptions) another aspect of nature (about which we
have an unconnected bunch of ideas). Of course whether or not the two domains are connected itself
involves, not exactly theory, but a hunch about the nature of nature. A slightly different example about
the sun will illustrate this.
How might we investigate Dicke's hypothesis that the interior of the sun is rotating to times faster
than its surface? Three methods have been proposed: (I) use optical observations of the oblateness of
the sun; (2) try to measure the sun's quadruple mass-moment with t he near fly-by of Starprobe, the
satellite that goes within four solar radiuses of the sun; (3) measure the relativistic precession of a
((footnote:))
6 See K.S. Shrader Frechette, 'Quark quantum numbers and the problem of microphysical
observation', Synthese 50 (1982), pp. 125-46.
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gyroscope in orbit about the sun. Do any of these three enable us to `observe' interior rotation?
The first method assumes that optical shape is related to mass shape. A certain shape of the sun
may help us infer something about internal rotation, but it is an inference based on an uncertain
hypothesis which is itself connected with the subject matter under study.
The second method assumes that the only source of quadruple mass-moment is interior rotation,
whereas it could be attributable to internal magnetic fields. Thus an assumption about what is going
on (or not going on) in the sun itself is necessary for us to draw an inference about interior rotation.
On the other hand, relativistic precession of the gyroscope is based upon theory having nothing to
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