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The
sun rises and the sun goes down
Whenever I read this sentence I hear a laud whisper of philosophers warning
me to ignore it. Don't you know that Ecclesiastes was wrong? You can't trust
your senses and intuition any more. The rising sun is an illusion. It is the
earth that moves, and not the sun, as Galileo has shown.
This dogma influenced my thinking for years. Only gradually I realized that
it is a well publicized legend, like many of this kind, spread by Physics.
Here is the story how this fascinating fable evolved.
It all started in Babylon
The rising sun, a mighty god welcomed Babylonians every morning. It was responsible
for man's affluence and prosperity, and it's awakening each morning proclaimed
hope. Yet from time to time this life giver was threatened by a demon, which
caused it to fade away as if abandoning earth. Was this god really threatened
or he simply demanded appeasement? This question was posed to astrologers,
which soon learned how to predict eclipses, and the behavior of other gods,
like moon and planets.
Abraham
Abraham realized that heavenly bodies could not be regarded as real gods. Their might was too limited. The sun god was bound to a circular path, known as ecliptic. The fate of planets was not better. They traveled in predictable and unexciting trajectories. Abraham simplified therefore Babylon's cosmology. Heavenly bodies became lifeless objects created by a unifying entity: '. . . and God made two great lights, the greater to govern the day and the lesser to govern the night; and with them he made the stars'. (Genesis, 1:16)
Ptolemaic system of AstronomyFrom then on astrologers,
and later on astronomers succeeded in describing the workings of heavens
with great precision. A cosmological theory originally conceived in
Greece, was completed by Ptolemy. The earth was the center of universe,
around which moved sun, moon and planets. Around this main circle, each
planet revolved in a smaller circle. The rest of the stars circled in an external
sphere.
Ptolemy and his followers convinced the Catholic Church that their model reproduces
God's creation. What started as a tool for computing eclipses became
God's creation.
Was interested in calculating
planetary positions. Ptolemy's calculations were extremely cumbersome, and
Copernicus searched for a way to simplify them. He found
that by placing the sun in the center of his universe-model, calculations
became simpler and faster. His model explained also the
occasional backward motion of planets. He believed that his model might represent
God’s creation better than Ptolemy's, but kept this to himself.
Using the newly invented
telescope Galileo realized that Copernicus' heliocentric model of the universe
was superior to that of Ptolemy. He tried to convince the Catholic Church
that our senses deceive us and that Ecclesiastes', "The sun rises
and the sun goes down", is an illusion. The sun is fixed in space, and
unchanging. Unfortunately Galileo was too determined, particularly since claiming
that he was right while the Church was wrong. He was too sure of himself,
and was therefore jailed.
Galileo was the founder of modern physics, and the initiator of
an ongoing feud between Science and Religion about who owns the truth.
Since truth means power, the feud is essentially about control. After publicly
recanting his claim, Galileo silently added "eppur
si muove." (still
it moves). Today it is obvious that he suffered in vain, since both
sun and earth move.
Kepler adopted Copernicus'
method for computing planetary positions. Nevertheless he found it difficult
to fit the orbit of Mars to the model. According to Copernicus, Mars
moved in a cycle. Astronomers however realized that Mars trajectory
is non-circular. It occurred to Kepler that an elliptical orbit might be more
appropriate to describe Mars' motion, and so he conceived his first law.
Once the ellipse was in place it was relatively simple to formulate the other
two Kepler's laws.
Kepler's model was promoted to the status of a law of nature. According to the Oxford dictionary of science (1): 'In science, a law is a descriptive principle of nature that holds in all circumstances covered by the wording of the law. There are no loopholes in the laws of nature and any exceptional event that did not comply with the law would require the existing law to be discarded or would have to be described as a miracle.'
How did Kepler arrive at his laws? Did he formulate them in order to improve his celestial model? Or, did the laws exist, in the world of ideas, waiting to be discovered? According to Platonists logical and mathematical entities exist independently of the empirical world and of human thought, waiting to be discovered.
Newton
Formulated/discovered the law of (universal) gravitation relating the
magnitude of the gravitational force between two bodies. Although the 'law' explains and predicts the interaction between two
bodies, it was proclaimed to explain
also the interaction between many bodies like in Kepler's model:
Every particle of matter attracts every other particle of matter with a force
proportional to the product of the particles' masses and inversely proportional
to the square of the distance between them. The universe was regarded as a
clockwork in which all components are tightly controlled. About
three centuries later, this naïve metaphor
was shattered by the mathematician Poincare who found that Newton’s
law is inadequate for predicting even the interaction between three
bodies. Apparently an universal law of gravitation does not exist,
and cannot be formulated since the three bodies interact chaotically.
For
centuries, Newton's law of gravitation was almost unrivalled as a fundamental
principle of physics. It bred generations of arrogant physicists who discovered
more 'universal laws.'
Einstein
Initially
Einstein seemed to be somewhat more modest than his contemporary physicists.
He only formulated a theory. His
special theory of relativity, is restricted to bodies which
are at rest or moving with uniform relative velocities. Traditionally in mechanics,
there was a simple procedure for treating relative velocities. The mathematical
equations involved are called Galilean transformations. However
the method did not work for electromagnetic radiation. In order to solve
this difficulty Einstein proposed that the speed of light is constant
for all frames of reference that are moving uniformly relative to each other.
Next, Einstein extended his theory to account for accelerating frames
of reference and called it general theory of relativity. The theory begins
with the fact that the mass of a body can be defined in two ways.
The inertial mass depends on the way it resists change in motion, as
in Newton's second law. The gravitational mass depends on forces of
gravitational attraction between masses. The two concepts, inertia and gravity
are equivalent.
Based on his theory, Einstein constructed a cosmological model of the universe. His equations were extremely complicated. In 1922 Aleksandr Friedmann succeeded simplifying the model by assuming that the universe expands.
To an outsider, the theory of relativity sounds like an oxymoron. All movements are relative except the light which is constant.
Stephen
Hawking
The British physicist, a leading
figure in the field of general relativity and the theory of black holes, published
a best seller, ‘A Brief History of Time’ . It describes his theory
that all matter and energy in the universe originated from a state of enormous
density and temperature, that once exploded and expands since.
Reading the book one is impressed how firmly Hawking believes in his model.
And yet it is based on a bold extrapolation from observations made in the last one hundred years,
back to the moment of creation. The model rests on three assumptions:
1. That the extrapolation is valid. 2. That Einstein theory is a law, and
3. That the universe started to be at a certain moment in the past.
Bold
extrapolation back in time
One wonders what makes Hawking's extrapolation better than the infinite other
possible extrapolations? Many of these putative models might even obey Einstein's
theory, with different behaviors. Some might oscillate, other might remain
invariant. After all how was the idea of an expanding universe conceived?
It was created to simplify Einstein's equations. Why not search for other
tricks to create even simpler universes?
Black
holes
Hawkings'
universe is haunted by bizarre beings called black holes. Celestial
objects that had undergone such a total gravitational collapse that no light
can escape from them. Objects of zero size
and infinite density. Black holes are also known as singularities:
Points in space at which the curvature of space is infinite.
In such circumstances the laws of physics are no longer
applicable (2). What do physicists mean by that? Why not state that at
these points the model fails? Particularly since in Calculus singularities
result from dividing a variable by zero. x = 0 is a singularity
for each of y = 1/x.
At
such a singularity in which 'laws of physics are no longer applicable', our
universe was born. How? Even Hawking cannot tell, and he asks Abraham
to take over : 'In the beginning God created . . .' Catholic Church loves
this idea.
Time Travel
Black holes fascinate physicists and philosophers which seriously discuss
the advantage of these entities for time travel and other desirable activities.
Since these entities do not obey physical laws, time travel will demand vehicles
that also do not obey physical laws. One wonders what drives rational minds
to irrationality.
Hawking
contra Kepler
It seems illuminating how in one stroke the Big Bang theory/law demolished
Kepler’s brain child. If indeed planets travel along ellipses. Each
planet ought to return to any point on its trajectory. Yet if the universe
expands, their trajectories will not fulfill this requirement. Imagine a planet
moving along the x-y plane, while the universe expands along the z-axis, planets
will spiral in this direction. Farewell to yet another Law.
Popper
Philosophers
are worried about the threat of the irrational. How to distinguish
between believable and non-believable theories? Popper says that we ought
believe in theories which could not be falsified, and have survived severe
testing. Only one observation of a non-elliptical planetary orbit will
refute the hypothesis. . . .
Can the Heliocentric model
really replace the Geocentric? Actually not. According to Einstein
"the two sentences 'the sun is at rest and the earth moves' or 'the sun
moves and the earth is at rest' . . .can be used with equal justification."
(3) Thank God for the rehabilitation of
Ecclesiastes. I may continue to admire the rising sun
and let it circle around me like a giant fly.
In his book 'Science and
Hypothesis', Poincare
expressed the view that laws of science, are conventions adopted for ease
and simplicity and not for 'truth'. Or perhaps they are only metaphors?
References
1.
A Dictionary of Science, Oxford University Press, © Market House Books
Ltd 1999
http://www.xrefer.com/entry.jsp?xrefid=489645&secid=.-
2.
Black holes and Singularities
http://www.xrefer.com
3. Einstein A, Infeld L. The Evolution of Physics. Cambridge University Press
p. 224,1938.