— Wilhelm Ostwald, Grundriss der allgemeinen Chemie (4th ed., 1909), Preface.
‘Why,’ said the Dodo,
‘the best way to explain it is to do it.’
— Lewis Carroll (Reverend Charles Dodgson (1832-1898), Alice’s Adventures in Wonderland, chapter III.
I would propose that
the chemists (or ex-chemists like myself) of my generation when they are introduced
to each other should each show the palm of the right hand: towards the centre, where
the tendon that flexes the middle finger crosses what palm readers call the life
line, the majority of them have a small professional, highly specific scar whose
origin I will explain… .Plugs of cork or rubber were used for retention; when (a
frequent thing, in order, for example, to connect the flask to a cooler) you had
to slip a piece of glass bent at a straight angle into a pierced plug, hold it and
turn it while pushing, the glass often broke, and the sharp stump plunged into your
hand.
— Primo Levi (1919 – 1987), ‘The Mark of the Chemist’ in Other People’s Trades, 86.
Better indeed is knowledge
than mechanical practice.
— Bhagavad Gita, 12:12, in the translation
of Eknath Easwaran, Arkana Books, 1985.
Fillet of a fenny
snake,
In the cauldron boil and bake;
Eye of newt and toe of frog,
Wool of bat, and tongue of dog,
Adder’s fork and blind-worm’s sting,
Lizard’s leg and howlet’s wing,
For a charm of powerful trouble,
Like a hell-broth boil and bubble.
— William Shakespeare (1564 – 1616), Macbeth,
IV, i, 12-19.
Yes, I have been guilty
of several monographs. They are all upon technical subjects. Here, for example is
one ‘Upon the Distinction Between the Ashes of the Various Tobaccos.’ In it I enumerate
a hundred and forty forms of cigar, cigarette, and pipe tobacco, with coloured plates
illustrating the difference in the ash. It is a point which is continually turning
up in criminal trials.
— Sherlock Holmes describes his methods in Sir Arthur Conan Doyle (1859 – 1930),
The Sign of Four.
There are essentially
two ways in which physicists at present seek to obtain a consistent picture of the
atomic nucleus. The first, the basic approach, is to study the elementary particles,
their properties and mutual interaction. Thus one hopes to obtain a knowledge of
the nuclear forces.
If the forces are
known, one should in principle be able to calculate deductively the properties of
individual complex nuclei. Only after this has been accomplished can one say that
one completely understands nuclear structures …
The other approach
is that of the experimentalist and consists in obtaining by direct experimentation
as many data as possible for individual nuclei. One hopes in this way to find regularities
and correlations which give a clue to the structure of the nucleus …
The shell model, although
proposed by theoreticians, really corresponds to the experimentalist’s approach.
It was born from a thorough study of the experimental data, plotting them in different
ways and looking for interconnections …
One of the main nuclear
features which led to the development of the shell structure is the existence of
what are usually called the magic numbers. That such numbers exist was first remarked
by Elsasser in 1933. What makes a number magic is that a configuration of a magic
number of neutrons, or of protons, is unusually stable whatever the associated number
of other nucleons. When Teller and I worked on a paper on the origin of elements,
I stumbled over the magic numbers. We found that there were a few nuclei which had
a greater isotopic as well as cosmic abundance than our theory or any other reasonable
continuum theory could possibly explain. Then I found that those nuclei had something
in common: they either had 82 neutrons, whatever the associated proton number, or
50 neutrons …
[After studying Elsasser’s
work and new data] the magic numbers not only stood up in the new data, but they
appeared more clearly than before, in all kinds of nuclear processes. It was no
longer possible to consider them as due to purely accidental coincidences.
The magic numbers,
as we know them now are:
2, 8, 20, 28, 50, 82, 126
and most importantly,
they are the same for neutrons and protons …
Sn, Z = 50 is the
element with the largest number of stable isotopes, namely 11. There are 6 stable
nuclei with 50 neutrons and 7 with 82 neutrons, whereas normally there are only
2 or 3 nuclei with the same number of neutrons …
For nuclei heavier
than Ca40 [40Ca], the number of protons is less than the number of neutrons
and only then does it become clear that the stability is connected with the neutron
number or the proton number, and not with the total number of both.
— Maria Goeppert Mayer, (1906 – 1972), Nobel
Prize speech, 1963.
Although I was drawn
to geometry, I had little interest in physics. The textbooks were simple, and I
could understand them easily on first reading. However, what was written there were
mere facts, and upon further thought, what lay behind the facts was elusive. This
unknown world was distressingly wide, and I could not find a handle to open the
door to it. No, I could not figure what or how to think about it. I could not find
suitable supplementary books, and the experiments we performed did not satisfy me
at all. Perhaps it was natural that I felt no interest.
— Hideki Yukawa (1907 – 1981), Tabibito
(‘The Traveller’), 100.
In the third year,
I would have to decide on a specialty … Professor Kimura’s spectroscopy was closest
to what I desired … the difficulty was that Kimura’s laboratory did not accept students
of theoretical physics …
If I were to be involved
in spectroscopy experiments, I had to be able to bend and connect glass tubing as
needed. Thus, I thought myself unqualified for the Kimura laboratory …
I visited Kawada-san
in his laboratory [and] a stranger entered the room; one could tell he was not a
physics researcher. His conversation with Kawada-san was about business, about the
type of machines to be ordered and their price. The conversation sounded like one
from an entirely unknown world, and I realised that to do experiments I would have
to deal with that sort of business. As I listened in silence, I thought that maybe
I could only do theory after all.
— Hideki Yukawa (1907 – 1981), Tabibito
(‘The Traveller’), 162 – 3.
I thank God I was
not made a dextrous manipulator; the most important of my discoveries have been
suggested to me by my failures.
— Humphry Davy (1778 – 1829)
It is known to all
persons who are conversant in experimental philosophy, that there are many little
attentions and precautions necessary to be observed in the conducting of experiments,
which cannot well be described in words, but which it is needless to describe, since
practice will necessarily suggest them; though, like all other arts in which the
hands and fingers are made use of, it is only much practice that can enable a person
to go through the complex experiments, of this or any other kind, with ease and
readiness.
— Joseph Priestley (1733 – 1804), Experiments
and Observations on Different Kinds of Air, 2nd edition, 1775.
You will find an index to this blog at the foot of this .link Please be patient: I am pedalling as fast as I can.
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