Science is hydra-headed. The answer to one question raises others. If
Symmetrical Impermanence solves some problems, it gives rise to many
more. Two of them are: What is an elementary component of the material
universe? How does its extinction affect the nucleus of an atom?
I can only suggest tentative answers to these questions and should like
to draw attention to their difficulty and their significance.
I have taken care throughout this book to avoid the impression that
an elementary component of the material universe is necessarily any of
the elementary particles with which nuclear physics has made us familiar.
It is partly for this reason that I chose this non-committal, if cumbersome,
name. The constituents of matter that, according to Symmetrical Impermanence, originate and become extinct may, for all that can so far be proved
to the contrary, be found among the protons, electrons, neutrons, and other
charged or uncharged particles that have so far been studied. They may,
of course, be smaller. Nothing has so far been said to refute the hypothesis,
if anyone cares to form it, that they are sub-particles and that the familiar
particles are structures produced by a process of synthesis. But it is implicit in Symmetrical Impermanence that the elementary components are
A few other considerations deserve brief mention.
Origins and extinctions should be expected to leave the average ratio
of mass to charge for the whole universe unaltered, for if they did not this
ratio would change with time. This suggests that whatever originates and
becomes extinct as a unit is neither mass nor exclusively charge, but either
a combination of both or something common to both.
Some objections to identifying those constituents of matter that I
have called elementary components with protons, neutrons or electrons
only have been mentioned in Chapter 3, Section 4. Mr Wilson, of the
Research Laboratories of the Central Electricity Generating Board, and
Dr Sciama, of Cambridge, have drawn my attention to another objection
to doing this. It leads to the second question, how does the extinction of
an elementary component affect the nucleus of an atom?
If an elementary component were a neutron or any charged particle
and became extinct in the complex nucleus of a radio-active substance, the
balance of forces in the nucleus would be upset. The consequence would be
the emission of other particles and of radiation, while what was left of
the nucleus would become that of a different chemical element. There
would, in short, be characteristic radio-activity. There would also be a
residue of the chemical substance into which the disintegrating atoms were
If the extinction of elementary components were the only cause of such
radio-activity, the half-life of the substance would equal the half-life of
matter. If there were additional causes, the half-life of the substance would
be shorter. But it could never be longer than the half-life of matter.
Now good reasons have been found in preceding appendices for
believing that the half-life of matter is likely to be not more than 4 x 108
years. If what became extinct were a proton or a neutron, no substance
could have a radio-active half-life greater than this value. But many
substances do have substantially greater radio-active half-lives. The radioactive half-life of most substances is indeed to all intents and purposes
From this it is clear that not every extinction of an elementary component causes radio-activity. It may be that none does so. But if some do
cause radio-activity, it can be only a small proportion. It would not be so
if the elementary component were a neutron or a proton forming part of
As mentioned above, the elementary component must have something
that is common to mass and charge and so its extinction must result in the
immediate, or delayed, disappearance of both from the nucleus. Therewith
the loss of stability would not be as great as it would if mass or charge
only were to disappear. It is worth investigating whether every nucleus
that suffered such combined loss would necessarily show radio-activity.
If the balance of forces was not greatly disturbed and the probability that
further particles would be emitted were small, there would be no reason
why the radio-active half-life should not greatly exceed the half-life of matter.
But the further difficulty mentioned above would remain. What was
left of the nucleus in which an extinction had occurred would be the
nucleus of a different chemical element. Extinctions must occur in nonradio-active elements and, according to this theory, a consequence of the
continuous extinction of matter is a slow change of their chemical constitution. With a half-life of 4 x 108 years such a change would presumably
be easily detected. If it does not occur, a different answer to the question
has to be found.
One answer would be that a complete nucleus becomes extinct. If so,
there is no chemical residue, no radiation, no emission of particles.
An observable effect would be the pulse of gravitation that was emitted
by the extinction. But the objection to this answer is that we regard the
nucleus as a very composite affair, as anything but an elementary component. But I should not reject this answer out of hand. Conceptual
distinctions do not necessarily coincide with real ones and it is not impossible that what is composite from the point of view of nuclear physics may
be simple from the point of view of Symmetrical Impermanence. It has to
be remembered that the individual constituents of the nucleus are not
observed while they are forming a part of it, but only while they are
outside. In Appendix H it will be shown that the nucleus of any element
may well be a more basic unit than is usually supposed.
If this is accepted many puzzles concerning the nucleus disappear. At
the same time the question is answered satisfactorily why extinctions are
not accompanied by radio-activity and why they do not leave a chemical
residue. The answer is that the unit to become extinct is always an entire
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