These Blogs are based on the lectures for a mini course on "Scientific Method for Non-Scientists".
Scientific Practice, Intuition and Temptation - Part II Temptation
Scientific Practice, Intuition and Temptation - Part II Temptation
Debi Prasad Choudhary
Los Angeles
07/23/2015
I started seriously liking physics after
reading a derivation of “Maxwell-Boltzmann distribution law” in the book
“Treatise on Heat” by Saha and Srivastava in my undergraduate honors class.
Those days, Feynman Lectures, Goldstein rotating top problem in Classical
Mechanics and Born and Wolf Optics were the exposure to physics and gave an
impression of solid foundation of the subject, which is hard to shake. That
changed when I started my career as a practitioner of scientific research.
In early 1980s, the journal Nature
published a series of paper on the cause of “mass extinction” events that occur
on earth every 30 million years, one of them causing the death of dinosaurs.
Among many hypotheses, I liked one that invoked the perturbation of “Oort Cloud”
due to the excessive nearby passing stars when the solar system move through
the galactic plane swing during its 250 million year journey around the
Milky-way Galaxy. On one occasion the Nature editorial wrote that the original
data for which these hypothesis are built is published in “Proceedings of
National Science Academy”, which is a serious Journal, but charges a fee for
publication. As a result of that publication, the field suddenly became “hot”
prompting a flow of ideas to explain. It exposed me to the competitiveness of
scientific research. On another occasion, the journal Nature invited four
leading scientists (J. V. Narlikar, Fred Hoyle, G. Burbridge and H. Arp) to
explain that their conclusion of “steady state” model of the universe is
scientific. Around the same time H. Arp wrote that denial of observing time on
Hubble Space Telescope is similar to the occasion when Galileo’s colleagues
refused to view through his telescope. Dr. Arp was asking for telescope time to
prove that the Quasars are not distant objects. The 1980s were exciting time,
and many of these publications in the Journal nature exposed me to the fierce
competition and vibrant debate in the field.
Towards the end of this decade, when I
was relaxing after writing my PhD thesis, “Cold Fusion Confusion” appeared that
gave a glimpse of over ambitious practice of scientific researchers. Nuclear fusion
occurs under high pressure (extremely high density) and very high temperature
like the conditions in the center of sun and stars that combine lighter
elements to produce heavier elements and energy. In mid-March 1989 two
scientists Fleischmann and Pons from US universities announced the experimental
result of fusion reaction in room temperature that was later proved to be
false. Their announcement were more motivated by securing grants among other
factors. In our laboratory, there was a large program on fusion research, which
ended up becoming a premier institute. So, there was considerable interest
among faculty and students. One of our senior, brilliant nuclear physics
professors presented a colloquium that started saying, even though the
experimental results turned out to be false, such reactions are theoretically
possible. After formulating his problem
systematically, he stated that the nuclear reaction rate of would be enhanced
many fold due to “some stochastic” process. Our director, who was also a
well-known nuclear physicist, insisted in elaborating this aspect, which was
not possible. So, he angrily advised to give up such non-productive ambitious
pursuit. That was a nice lesion for me in the beginning of scientific career.
At later stage, I took interest in this
area and came to know many fascinating anecdotes, such as how C. V. Raman
played a role in rejecting a grant proposal of famous astrophysicist M. N. Saha
for a spectrograph. Several scientist like Hewish, Raman and Watson utilized
others work, mostly their students research results without due
acknowledgements. I also learnt how Newton’s corpuscular view of light
prevented many scientists to develop wave theory for over a century. In
following, we shall discuss three famous example of scientific result that had
great influence in the contemporary science.
Results from famous Total Solar Eclipse
expedition by Sir Arthur Eddington is often used to illustrate selective use of
data to prove a biased scientific idea. In 1919, Eddington observed a total
solar eclipse to measure the apparent shift of position of stars in the sky
near the solar limb. According to Einstein’s theory of relativity the position
of stars around the sun would shift by about 2 arc second due to the curvature
of space-time by the solar mass, which is twice as much predicted by Newtonian
mechanics. Eddington obtained photographs of eclipsed sun along with the
surrounding stars, which were faint and not well recorded on the photographic
plate. There were two independent groups. Many research on the work of
Eddington suggest that, he selected the measurements of stellar position that
supported Einstein’s General Theory of Relativity and did not consider other
measurements seriously without giving proper reason. This is often attributed
to Eddington’s eager to prove that Einstein was correct. Eddington was greatly
influenced by the beauty of this theory and also wanted to elevate Einstein for
political reason. Even though, Eddington was biased in selecting the data, his
intuition was correct, as we know today the validity of Einstein’s theory.
There are numerous examples of consequence of General Theory of Relativity, one
of them being Einstein Ring observed by Hubble Space Telescope. But, the first
experimental test of this theory by Eddington seems to be biased!!
Use of selected data in the famous Noble
Prize winning oil drop experiment by Robert Millikan to determine charge of
electron and prove that it is discrete is widely quoted as an example of
scientific impropriety. Millikan observed vertically falling electrically
charged oil drops in a space between two plates with that are connected to
battery. The fall of oil drops are halted by applying a certain amount of force
due to the voltage on the plates which was always multiple of certain number, the
charge of the electron. Although the numerical value was not correct due to the
use of wrong viscosity of air, Millikan was so confident about the experiment
that he said, “one who has seen this experiment, has seen the electron”. In
fact, that is true and these days most undergraduate students perform this
experiment. In order to arrive at the conclusion, he used 58 measurements taken
over 60 days out of 150 measurements over about five months. Yet, he mentioned
in the publication “It is to be remarked, too, that this is not a selected
group of drops, but represent all the drops experimented upon during 60
consecutive days”. Many scholars have
examined the notebook and conclude this as not appropriate. This experiment
that fetched Nobel Prize in 1920, dominated early developments of modern
physics and many did not dare to report the value of electron charge if it
deviated too much from Millikan’s values. Richard Feynman in Caltech commencement
address in 1974 comments: “We have learned a lot from experience about how to
handle some of the ways we fool ourselves. One example: Millikan measured the
charge on an electron by an experiment with falling oil drops, and got an
answer which we now know not to be quite right. It's a little bit off because
he had the incorrect value for the viscosity of air. It's interesting to look
at the history of measurements of the charge of an electron, after Millikan. If
you plot them as a function of time, you find that one is a little bit bigger
than Millikan's, and the next one's a little bit bigger than that, and the next
one's a little bit bigger than that, until finally they settle down to a number
which is higher.
Why didn't they discover the new number
was higher right away? It's a thing that scientists are ashamed of-- this
history--because it's apparent that people did things like this: When they got
a number that was too high above Millikan's, they thought something must be
wrong--and they would look for and find a reason why something might be wrong.
When they got a number close to Millikan's value they didn't look so hard. And
so they eliminated the numbers that were too far off, and did other things like
that. We've learned those tricks nowadays, and now we don't have that kind of a
disease”.
Famous Mendel’s experiment on plant
hybridization is also not free from critical scrutiny. Gregor Mendel, an
Austrian monk, carried out an elaborate experiment that contradicted the
contemporary view of many biologist who thought all offspring were mixture of
parental traits that could never be traced back to parents and eventually blend
together resulting in a homogeneous amalgamation of parental characters. Mendel
noted that “hybrids from seeds having one or other of the two differentiating
characters and of those one half develop again the hybrid form, while the other
half yield plants which remain constant and receive the dominant or recessive
character in equal numbers”. In his experiment, pea plants exhibited either
green or yellow seeds, but not both colors within the same plant that blended
yellow and green. In the first generation of hybrids that trait always mirrored
one of the parents. In the second generation the traits reappeared in 3:1
proportion such that out of every four offspring approximately three possessed
the physical trait of one parent and one displayed physical trait of the other.
Many researchers thought the conclusions are too good to be true and doubted
the unbiased data collection and analysis in the original experiment.
Scientific research is to unravel the
natural laws, as we perceive them. Many experimental scientists are influenced
by dominant ideas and influenced by contemporary socio-politics. Subject of
climate change may be one such example for the modern era. These issues may
influence the conclusion of experimental results. But, good experiments always
keep complete record of entire investigation process and give opportunity to
colleagues to examine their validity. So, even if the conclusion of original
experimenter may be flowed, the wrong results do not survive long.
