The Context
Authority, dogma, faith, belief,
superstition, etc., are human traits found all too commonly in almost all walks
of everyday life. However, one doesn't expect to encounter them in the
world of science which is characterized precisely by their absence. But, since science cannot always be separated
from what scientists do, it is not uncommon to find these traits in the day to
day affairs and actions of scientists.
The Eddington affair narrated here is a classic example of this.
The history of science is replete with such episodes that have had an immediate
negative impact on the march of scientific progress*. However, the damage
has always been temporary; science in its relentless pursuit of truth has
always bounced back and triumphed in the end. Even Eddington's influence
could not negate the white dwarf star theory for too long. The scientist
advocating the theory may have suffered, but not science itself. This amazing
proclivity is what sets science apart from other human pursuits.
I had also gone on to add
parenthetically, “*This is far too important
for just a casual reference like this and I
intend to expand on the theme in a future blog post.”
It
is now time for me to follow up on this promise, taking a few glaring examples
from the history of physics to drive home my point, in addition to the
Eddington-Chandrasekhar episode discussed earlier. These examples are discussed not so much to
highlight an immediate negative
impact on the march of science as in the Eddington episode, but as major
roadblocks and diversions in the path of scientific progress and for their
historic importance. My choice of
examples has been dictated largely by my professional background, which is
mainly physics, and I am sure such examples abound in other branches of science
as well. However, I hasten to add that I
have endeavored to communicate my ideas in a non-technical language and with
their essence understandable to all categories of readers.
Aristotelian Legacy and the Copernican
Revolution
Following
in the footsteps of his illustrious predecessors Socrates and Plato, and
belonging to the golden era of Greek civilization, the very cradle of human
civilizations, Aristotle (384 BC – 322
BC) was perhaps the greatest contributor
to original knowledge the world has ever known.
His work and writings in
philosophy, science, mathematics, metaphysics, art, poetry, politics,
logic, rhetoric, morality and a host of other disciplines made him a sort of all-in-one
walking encyclopedia, something that was possible only in such early times in
the history of civilization.
In
the realm of science, while Aristotle’s contributions to what may be broadly
called biology stood the test of time to a considerable extent, most of his
contributions to what later came to be termed physics were only like castles in
the air, without firm foundations. They
were founded largely on the process of reasoning rather than experimentation,
the hallmark of true science as was to be demonstrated by Galileo nearly two
thousand years later.
Such
an aura of reputation was built around Aristotle that he came to represent all
that was authoritarian, revered and dogmatic as much in science as in other
disciplines, stifling its growth for a very long time to come. The Aristotelian
legacy was to do more harm than good, especially in the hands of the powerful
Roman Catholic Church which ruled and controlled the minds of people based on
such authoritarian precepts.
One
such legacy was the geo-centric world view that placed earth at the centre of everything
in the universe and would not tolerate any arguments or even evidence to the
contrary. The observed motions of
heavenly bodies – planets, stars, the Sun and the Moon – were all artificially
made to fit into a geocentric system through some tortuously complex mechanisms
conceived by Ptolemy and others just to preserve appearances and essentially to
conform to church dictates.
The
geocentric system had met a feeble challenge from people like Aristarchus even
in ancient times but it was only in the mid sixteenth century that it was
confronted with a formidable and eventually victorious rival in the form of the
heliocentric (sun-centered) model proposed by Nicolaus Copernicus, a Polish
monk who summoned enough courage to publish his arguments towards the end of
his life knowing he would not live to see their acceptance. Based largely on observational evidence he
effectively dethroned the earth from its central pedestal and showed how a
sun-centered system accounts for the observations elegantly without all the
complexities devised by Ptolemy and others.
It took nearly a hundred years more for its universal acceptance through
systematic mathematical analysis by Johannes Kepler and the subsequent clinching
observational evidence provided by the great Galileo to the consternation of
the church. The rest is history.
Science
had fought a long hard battle lasting many centuries, unparalleled in the
history of human thought, before triumphing over authoritarian religious dogma
that had tried to stifle the quest for objective truth.
Ironically,
thanks to the power of mathematics coupled with the speed of number crunching
operations with computers, it is indeed irrelevant whether we adopt a
heliocentric or geocentric or any other world view today. Nevertheless, the Copernican revolution
uprooting the Aristotelian legacy was a major milestone in the history of
scientific advancement.
Falling Bodies
A
popular ‘prediction’ of Aristotelian arm-chair logic was that a heavier object
would fall faster than a lighter one if dropped from the same height on
earth. Like the emperor’s invisible
clothes unveiled by an innocent child, it took a simple demonstration by
Galileo centuries later to unravel the fallacy of this. Contrary to popular belief, there is no
conclusive evidence that Galileo actually employed the leaning tower of Pisa to
demonstrate that bodies of different weights took the same time to hit the
ground when dropped simultaneously from the same height. However, he certainly delivered a death blow
to the myth. A convincing explanation as
to why this is so had to await Newton, Galileo’s worthy successor in the
scientific firmament. Using Newton’s
(universal) law of gravitation, coupled with his second law of motion, it can
be shown that different masses acquire the same acceleration under the earth’s
pull of gravity.
If
there were any doubters, the Apollo 15 astronauts demonstrated this live with a
hammer and a feather on the airless surface of the Moon for all TV viewers to
see. However, there are some people who
doubt that astronauts ever went to the Moon!
There is no question of convincing them of anything!
Aristotle’s
authoritarian influence was so strong that it had occurred to no one to put his
argument to a simple observational test.
The idea that observational/experimental evidence and not arm-chair
logic would be the final arbiter in any dispute was virtually unknown. From the perspective of scientific pursuit
today it is absolutely astonishing that this remained so for centuries until
the advent of Galileo on the scene. No
wonder science historians consider Galileo as the true father of modern
science.
Nature of Light
Few
things in everyday life are more familiar to us than light that enables us to
see things around us. Incidentally, we
can only see objects that reflect/scatter or emit light, but not see light
itself. One of the most fascinating
questions about the world around us concerns the nature of light itself – What
is it? What is it made of it? How does it travel? At what speed? Etc.
It
has long been recognized that light carries energy and travels at a finite,
though enormously high, speed. It was
Newton who first proposed the corpuscular theory of light according to which it
consists of corpuscles (particles) travelling in straight lines and can be
reflected off material surfaces like bullets or pierce through transparent
materials similarly. On the face of it, this was an elegant and viable theory of light, accounting for some well-known
properties, including reflection and refraction (bending when passing from one
medium to another). It held sway for a
long time but eventually ran into serious trouble.
Newton
himself had discovered a property of light that led to the formation of colored
fringes when white light was reflected off very thin material. We often see this when oil from a truck has
leaked and spilled over a smooth road coated with a thin layer of rain. Called interference,
this phenomenon defied explanation under the corpuscular theory. Also, Newton’s theory predicted that the
speed of light should decrease when it refracted from a dense medium like glass
into a rarer medium like air, but actual observations later showed just the
opposite. Another phenomenon that defied
explanation was diffraction, the
observed bending of light and formation of fringes when it passes through very
narrow obstacles or at straight thin edges like a razor blade. Yet another property of light called polarization fell totally outside the
scope of the particle theory.
All
these phenomena posed an insurmountable challenge to Newton’s theory much to
his mounting annoyance when he realized that a rival theory proposed in 1678 by
Dutch physicist Christian Huygens threatened to overthrow his own pet theory.
Huygens
realized the need for a better theory of light considering that some of its
properties were akin to those of mechanical waves on the calm surface of water in
a pond, generated and propagated when an object is dropped or dipped into
it. He visualized every point in a
medium through which light passed as a secondary source of spherical wavelets,
propagating at constant speed and carrying energy in the direction of motion of
the light ray. Each of these wavelets
gave rise to others in turn, thus setting up an expanding wave form much like
the two dimensional waves we observe on the surface of water when disturbed. With such a model he was able to explain
practically all the phenomena where Newton’s corpuscular theory had
failed.
As
in the case of Aristotle and his geocentric world view, Newton’s exceptional fame
and authority was to thwart the acceptance and use of Huygens’ wave theory for
quite a long time, to which Newton’s own attitude and opposition contributed in
no small measure. Eventually, it
received its due recognition and Newton’s theory was duly consigned to the
dustbin of history.
Rather
curiously, Newton’s particulate picture of light underwent a sort of revival
when Einstein came up with his photon theory of light in early twentieth
century to explain certain phenomena that had been freshly discovered and had
defied explanation by the wave theory itself.
However, the photons that Einstein visualized were packets of energy
whose magnitude depended on the wavelength of the light in question and bore only
a superficial resemblance to Newton’s corpuscles.
The
wave theory itself underwent a metamorphosis in mid nineteenth century in the
hands of Maxwell who bestowed on it an ‘electromagnetic’ character and a vastly
expanded scope. Also, the
electromagnetic wave theory and the photon theory were both found to be
perfectly valid descriptions of nature in their respective domains of
applicability and the ‘duality principle’ associated with them became a
fundamental attribute of nature.
The Enigmatic Aether
Historically,
an inescapable implication of the wave theory of light, either the classical or
the electromagnetic version, was that light waves required a medium to pass
through just like mechanical waves (two common examples of which are
longitudinal sound waves through air and transverse waves on the surface of
water). The fact that light from the Sun
and stars are found to travel vast distances of empty space posed an obvious
contradiction. Since physicists in those
days found it impossible to conceive of light without an associated medium,
they decided to bestow such a material property to empty space itself and
called this hypothetical medium the aether!(often
also spelt as ether). However idiosyncratic the idea may sound
today, it was looked upon as perfectly sensible, indeed very essential, in
those times.
When
a systematic study was made of the properties that such an all pervasive medium
ought to possess, it was deduced that the luminiferous aether should have, as
one writer put it, “… some fairly impressive physical properties. It was simultaneously a fluid (in order to
fill space) but also more rigid than steel (to support the high-frequency
oscillations of light waves). Aether
could have neither mass nor viscosity, otherwise it would affect the motions of
the planets. Finally it had to be
non-dispersive, transparent, incompressible, and continuous at a very small
scale.” Apart from such absurdly
impossible properties the aether would also provide, according to Newton’s
ideas on space and time, “a universal frame of reference, and all other motion
(like that of the Earth around the Sun) occurred relative to this frame, moving
through the aether.”
Even as the notion of the aether clung to the
body of physics like a leech, American physicists Michelson and Morley came out
with the findings of a historic and super-sensitive experiment that settled the
question once for all – the aether could not exist; otherwise their experiment
would have easily detected its presence! This ‘cognitive dissonance’ between theory
and observation wouldn’t go away easily until Einstein came up with his revolutionary
theory of relativity that totally dispensed with the need for the existence of
any exotic medium like the aether.
Sanity was finally restored, but the progress of physics had suffered
considerably because of its conservatism.
The N-Ray Episode
In
1903, Rene Blondlot, a well-known French physicist working in the University of
Nancy, announced the discovery of a new form of radiation analogous to X-rays
and named it N-Rays. This followed a
spate of publications about the supposed properties of these novel radiations,
with over a hundred scientists involved.
These rays were supposed to be emitted by most substances, including the
human body. This ‘discovery’ excited
international interest and a fair amount of skepticism as well by people who
couldn’t reproduce the effect, including Lord Kelvin and William Crookes in
England.
The
noted American physicist Robert W Wood, also known to be something of a
prankster and debunker of nonsense, was one of those welcomed by Blondlot to
his laboratory to see a first-hand demonstration. Wood smelled a rat and stealthily removed a
prism used as an essential piece of equipment in the darkened room and the
experimenters still claimed the ‘detection’ of the N-rays. He similarly replaced the object supposed to
be emitting the rays with a dry piece of wood (no pun intended), and with the
same result. He duly reported his
findings and the N-ray related publications declined exponentially and soon died
away. The episode became an example of
what Irving Langmuir called pathological
science.
Blondlot’s
claim was not really a hoax as many such claims actually are, but illustrates
the lack of unbiased objectivity and illusionary tendencies that sometimes
haunts even scientific investigations. The
episode illustrates how even hardened scientists can sometimes become highly
subjective and claim findings that matched their a priori expectations. It is
very frequently cited as a classic example of the dangers inherent in
experimenter bias, the very antithesis of good science. The history of science is replete with many
examples not only of such delusional discoveries, but also outright hoaxes and
plain cheating. I would like to reserve
them for separate treatment in a later blog. But the bottom line is that science has always bounced back from such setbacks and triumphed in the
end.
The ‘Martians’
Extraterrestrial
life has been an eternal fascination for all mankind. This is also the dominant theme of all
science fiction. But till date there is
no evidence of the actual existence of advanced life forms anywhere outside our
mother planet. While this has never
bothered fiction writers from conjuring up their tales, hard headed scientists
have also occasionally fallen prey to the temptation of interpreting highly
questionable observations as evidence in favour of extraterrestrial life.
Giovanni
Schiaparelli, a reputed Italian astronomer, made numerous telescopic
observations of planet Mars during its opposition in 1877 and observed a dense
network of linear structures on its surface, which he called ‘canali’ in
Italian but was loosely translated into ‘canals’ in English, and drew worldwide
attention as representative of the handiwork of intelligent life on the
planet. Questionable observations mingling
with unquestionably wild speculation led to the hypothesis of the ‘Martians’
and a fancy folklore and colorful fiction grew up around it.
Adding
fuel to the fire was the role of the American astronomer Percival Lowell who
became a strong votary for the existence of intelligent life on Mars based on
his own ‘supportive’ observations and interpretations. Though it was soon conclusively established
that what these two astronomers and their supporters had observed was just some
optical illusion, compounded by poor quality optics, the hysteria didn’t die
away easily. As recently as 1938, Orson
Welles was successful in frightening vast radio audiences out of their wits
through a fake ‘live’ broadcast of an
attack on Earth from these ‘Martians’.
It
was not until the early sixties of the last century that all speculation about
unusual features and happenings on the surface of Mars were fully dispelled
through close-up pictures and studies of the planet by NASA’s Mariner space
crafts.
In
recent months, Curiosity the NASA
automated Mars Science Laboratory roaming on the surface of the red planet has
made some tantalizing discoveries, but no evidence of any form of life has emerged as yet, nor is any really expected to
turn up in this mission.
The Elusive Neutrino
Radioactivity
is the process of emission of ionizing radiation by unstable atomic
nuclei. Three such processes are common,
involving the emissions of what came to be called alpha rays, beta rays, and
gamma rays respectively. When an alpha
particle (stable nucleus of helium) is emitted the unstable parent nucleus
decays into a more stable daughter nucleus of a different element. When a beta particle (an electron) is emitted
the parent nucleus decays into another nucleus in which one neutron will have
changed into a proton. When a gamma ray
(a high energy photon) is emitted the unstable nucleus loses some of its excess
energy and drop down to a lower, more stable, state without undergoing any
elemental transformation.
In
all the transformations involving radioactive decay and other nuclear
processes, the fundamental principles of conservation of energy, linear
momentum, and angular momentum (spin) are inviolable. But beta decay had raised grave questions
about the validity of one of them and driven physics into a major crisis before
being resolved in a manner that marks one of the greatest triumphs of the
scientific method.
In
beta decay, the parent nucleus emits an electron (or a positron) and changes to
another nucleus as in the following example: 6C14 -> 7N14
+ (-1)e0. The root
of the trouble with beta decay was that the sum of the energies of the decay
products was invariably less than the
energy of the parent, though not always by the same amount. The beta energies exhibited an unexpected
continuous spectrum up to a maximum value and this was another puzzle. Even the momentum was not fully accounted
for. These anomalies prompted a series
of very sensitive and precise measurements, thereby giving a boost to
experimental techniques, but could not be resolved. The community of nuclear physicists the world
over faced such a serious situation that some of them were even prepared to
abandon the cherished energy conservation principle, at least in the beta decay
process.
The
stage was set for a radical solution to the crisis proposed around 1930 by an
extraordinarily brilliant Austrian theoretical physicist, Wolfgang Pauli, best
known for the ‘Exclusion Principle’ named after him and a founding father of
the New Quantum Mechanics. Realizing
that his idea might not be accepted for formal publication, he informally
postulated in a conference of ‘radioactive’ physicists the existence of an
unknown neutral, massless, and chargeless particle that carried away just the
amount of unaccounted ‘missing’ energy!
Furthermore, he attributed its non-detection to its exceptionally low interaction
with matter in any form! The equation in
the example cited earlier would now read: 6C14 -> 7N14
+ (-1)e0 + 0n0 where n represents the new particle later
called the neutrino (actually its
anti-particle). The whole idea sounded so
outrageously unconventional, even ridiculous, that it met with little
enthusiasm despite having come from one of the founders of the new quantum
mechanics. But not for too long!
The
celebrated Italian physicist Enrico Fermi, one of the all-time greats in the
history of physics, took up Pauli’s idea seriously and incorporated it into a
very sound quantum-mechanical theory of beta decay that conferred virtual
acceptance to the neutrino hypothesis.
But the clinching evidence came from the elaborate and successful experimental detection of the particle
by Clyde Cowan and Frederick Reines in 1956, an eventual Nobel Prize winning
effort.
Today
the neutrino is so well known as to constitute an integral part of any
fundamental theory of astro-particle physics and we even have ‘neutrino
telescopes’ in operation in some parts of the earth deep underground.
Fusion, hot and cold
Even
small amounts of matter can be transformed into enormous amounts of energy
under certain conditions in accordance with Einstein’s famous relation between
the two, E=mc2, c being
the speed of light and equal to a huge 300,000 km/sec. Nuclear fusion is the process taking place all the time deep inside
most stars, including of course our Sun, by which energy is generated by the
fusing together of four hydrogen nuclei (protons) effectively into one helium
nucleus. Nuclear fission is the opposite process in which a heavy nucleus
like uranium breaks up into smaller fragments, also releasing energy because of
a net reduction in mass.
Both
these forms of energy have been harnessed on earth by Man. While fission energy has been put to use for
both constructive (as in nuclear power reactors) and destructive (as in nuclear
weapons) purposes, fusion energy is so far confined to destructive purposes
only, with the ‘hydrogen bombs’ based on fusion deadlier than the ‘atom bomb’
based on fission.
Nuclear
fusion requires the material (hydrogen nuclei) to be heated to temperatures of
the order of tens of millions of degrees, a requirement easily fulfilled inside
most stars. In ‘hydrogen bombs’ such
temperatures are uncontrollably created by the initial explosion of a fission
bomb that acts as a trigger.
Because
of the virtually limitless supply of hydrogen in the form of water on earth,
controlled fusion energy can be a solution to all our energy needs if it can be
harnessed in a controllable manner. Till
now this has been just a pipe dream because of formidable technical problems
that persist in spite of huge investments in resources and efforts spread over
the last 5-6 decades.
It
is in this context that a claim in 1989 from two scientists, Martin Fleishmann
in UK and Stanley Pons in USA, created worldwide interest, excitement, and even
sensation. They claimed to have produced
fusion energy in small amounts in a room
temperature tabletop experiment involving electrolysis of heavy
water (in
which the hydrogen atom of ordinary water is replaced by its heavier cousin deuterium that is made up of a proton
and a neutron) on the surface of a palladium electrode. It soon failed one of the most fundamental
tests for good science and a basic tenet of the scientific method –
reproducibility.
As
summed up by a reviewer at that time, “Many scientists tried to replicate the
experiment with the few details available.
Hopes fell with the large number of negative replications, the
withdrawal of many positive replications, the discovery of flaws and sources of
experimental error in the original experiment, and finally the discovery that
Fleischmann and Pons had not actually detected nuclear reaction byproducts.” Like the N-ray episode discussed earlier, in
course of time this ‘Cold Fusion’ episode came to be regarded as another
instance of pathological science.
The
fact that many die hard experimenters still continue to pursue their cold
fusion researches does not necessarily bestow any authenticity for cold fusion
as opposed to hot fusion which is a demonstrated fact, though it has proved
impossible to harness for peaceful purposes till now.
Faster than light entities
Einstein’s
Theory of Relativity sets an upper limit on the speed that anything can travel
with respect to anything else. This is
the well-known speed of light whose value is close to 300,000 km/sec. Nothing can travel faster than this under any
circumstances and this is one of the most fundamental truths of nature. Even science fiction writers seem to respect
this and try to overcome the limitation in devious ways such as travelling
through hypothetical worm holes in space-time to bridge the travel time gap. Space travel to distant stars and their
planets is a virtual impossibility because of the enormous span of time, a few
thousand years at the very least, involved in just reaching such a place even
using highly futuristic technology.
Einstein’s
theories have withstood every conceivable challenge repeatedly, both
theoretical and observational, and the concept of the ultimate speed inherent
in them has found experimental support in innumerable ways. For example, it is a well-established fact
that the speed of a fundamental particle such as the proton doesn’t reach the
speed of light (though it comes tantalizingly close to it) even when imparted
the fullest possible energy employing the world’s largest particle accelerator,
the Large Hadron Collider (LHC) at CERN near Geneva. All the gargantuan energy goes to increase
the mass of the particle, not its speed beyond the limit.
Not
to be discouraged by nature-imposed limitations, some physicists, including the
highly respected India born George Sudarshan, proposed particles called tachyons with an ‘imaginary mass’ that
would always travel faster than the speed of light. This idea has remained only as a mathematical
curiosity without any application or relevance in the real world.
Against
this background came the stunning news from the CERN-associated OPERA
experiment in the Gran Sasso Laboratories in Italy in September 2011 that
neutrinos produced at CERN travelled faster
than light through the earth’s crust (nothing is impervious to neutrinos)
and reached their detector about sixty nanoseconds sooner than they ought to
have! To be fair, the OPERA team
announced this with caution and emphasized that the findings that had emerged
over a significant period of time needed to be double-checked and replicated elsewhere
though their own findings were inside the confidence level for such
measurements. Yet the news was received
with a wide spectrum of reactions, ranging from contemptuous dismissal to
qualified acquiescence, with the majority reaction being studied skepticism so
characteristic of the method of science.
While most people were resigned to waiting for further developments
there were some who jumped to a variety of speculative conclusions and started
publicizing them in various media. Novel
theories accommodating faster than light entities also started cropping up
without sufficient regard to their implications for existing ones.
One
of the observations strongly against the superluminal (faster than light) neutrinos
was a major astrophysical observation associated with the great supernova of
1987 that was detected in the Large Megellanic Cloud, a satellite galaxy about
168,000 light years away in the southern skies.
Two to three hours before the visible light
from this supernova explosion reached the Earth, a burst of neutrinos was observed at three separate neutrino observatories. This is due to
expected neutrino emission which occurs simultaneously with the event. If these neutrinos had been travelling as
fast as the Gran Sasso neutrinos they should have arrived about four years before the light did, not
just a few hours!
An
undercurrent of controlled chaos prevailed in the world of physics for some time
before the ICARUS study of the same type of events from the same source, also
at Gran Sasso, restored the status quo once for all in favour of Einstein’s
theory as could only be expected. As a
large number of observers had so strongly suspected, the earlier measurements
had suffered from instrumental calibration errors. Coming from such an internationally reputed
institution this was not quite acceptable and two of the prominent people
involved in the first announcement had to resign from their positions. More importantly, sanity had been restored
and science had triumphed yet again.
Summation
Ever
since its quest began for objective truth and unraveling the workings of
nature, the path of scientific progress has never been smooth. It has often been strewn with roadblocks, bottlenecks,
misdirections, diversions, pitfalls and other impediments and suffered the
consequences. However, because of its
unique self-healing nature, science has always recovered from its setbacks and
come out ultimately triumphant as the episodes narrated here demonstrate. The work of scientists may have suffered from
a whole gamut of human shortcomings – subjective judgments, misjudgments, prejudices, authoritarian
influences, dogma, superstitions, bias, dissonance, professional jealousies, conservatism,
a certain degree of lemming mentality, plagiarism, deceit and even cheating – but
in the long run and last analysis these have not done any lasting damage to
science itself. Paradoxically perhaps,
it has in fact emerged stronger.
