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| Arthur Eddington |
The Nature of the Physical World is the title of a landmark work in the history of popular science. Published in 1928, it compiles the Gifford lectures given in Edinburgh by its author, Arthur Eddington, in 1927. Eddington was then famous, having been the scientist who, in 1919, on the occasion of a solar eclipse, organized the expedition that proved one of the predictions from Einstein's theory of General Relativity: the deflection of light when passing near a star. It was said of him that he was one of only three people in the entire world who understood General Relativity. In addition to this, Eddington was a pioneer researching on the origin of the energy of stars, for he was the first to propose that it came from the fusion of hydrogen to form helium.
In this book,
Eddington summarizes the science of his time, focusing mainly on the great
advances of the late nineteenth century, and especially the early twentieth
century, which had revolutionized physics: thermodynamics,
Rutherford's atomic theory, the theory of Relativity, and quantum theory.
The first thing
that has caught my attention in this book is that, unlike other scientific
popularizers, the most famous of which was Stephen Hawking, Eddington has very clear ideas
and knows how to distinguish perfectly between science and philosophy. It is surprising, and at the same time disturbing,
that in the more than 90 years since the publication of this book, this very
important distinction has been lost, perhaps as a consequence of the divorce
between humanistic studies and scientific studies in teaching. Scientists today
know almost nothing about philosophy and bungle as soon as they try to do it
(often they don't even realize what they are doing), whereas many philosophers
know almost nothing about science. That is why the branch called philosophy of science is so important. One of its pioneers was precisely
Eddington.
Another
surprising thing is that almost everything Eddington said in summing up the
science of time still applies today. Should we deduce that science has made
little progress in the last 94 years? The part that has most lagged behind is
the atomic theory, since the neutron was not discovered until 1931, and the
quark theory in the sixties. Eddington also did not know at that time the
theory of the expansion of the universe and the Big
Bang (proposed by Georges Lemaître in 1927 and 1931), or
the cosmic background radiation, discovered in the 1960s, which reintroduced an
absolute space-time framework. However, he foresaw some of these things,
although he did not like some of them, as can be seen in these quotes on
cosmology from chapter 4:
Travelling
backwards into the past we find a world with more and more organisation. If
there is no barrier to stop us earlier we must reach a moment when the energy
of the world was wholly organised with none of the random element in it. It is
impossible to go back any further under the present system of natural law. I do
not think the phrase "wholly organised" begs the question. The
organisation we are concerned with is exactly definable, and there is a limit
at which it becomes perfect...
As a
scientist I simply do not believe that the present order of things started off
with a bang…
I
would feel more content that the universe should accomplish some great scheme
of evolution and, having achieved whatever may be achieved, lapse back into
chaotic changelessness, than that its purpose should be banalised by continual
repetition. I am an Evolutionist, not a Multiplicationist. It seems rather stupid
to keep doing the same thing over and over again.
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| Albert Einstein |
Against
Einstein's ideas about time (Einstein thought that the passage of time is an
illusion), Eddington offers the following example: if we mix a deck of cards,
the order disappears. If we reorder the deck, the order is restored. But if we
reverse the sense of time after shuffling a deck, the situation is not
symmetrical, because there is no "unmix" operation. The actions
(causes) of shuffling and sorting are different, not inverse. The human mind
intervenes in ordering, not in mixing. In those cases, time cannot reverse its
meaning, because what is obtained does not make sense. In this context we have this
well-known quote, also from chapter 4:
If
someone points out to you that your pet theory of the universe is in disagreement
with Maxwell's equations—then so much the worse for Maxwell's equations. If it
is found to be contradicted by observation—well, these experimentalists do
bungle things sometimes. But if your theory is found to be against the second
law of thermodynamics I can give you no hope; there is nothing for it but to
collapse in deepest humiliation…
A quote from
Chapter 5 raises the problem of the limits of physics:
Thanks
to clear-sighted pioneers in the last century science became aware that it was
missing something of practical importance by following the inventory method [reductionism]...
Entropy became recognised although it was not found in any of the compartments…
by it science has been saved from a fatal narrowness. If we had kept entirely
to [reductionism], there would have been nothing to represent
"becoming" in the physical world. And science, having searched high
and low, would perhaps have reported that "becoming" is an unfounded
mental illusion—like beauty, life, the soul, and other things which it is
unable to inventory.
In the next post
I’ll speak more about this book.
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