Scientific Practice, Intuition and Temptation - Part II Temptation

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

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. 

Scientific Practice, Intuition and Temptation - Part I Intution

These Blogs are based on the lectures for a mini course on "Scientific Method for Non-Scientists".

Scientific Practice, Intuition and Temptation - Part I Intution

Debi Prasad Choudhary

Los Angeles

07/16/2015

Hypothesis, verification with experiment and revising based on the outcome are the foundations of scientific method. This straight forward sounding simple principle is really very complex in practice. The hypothesis is actually educated guess, in which intuition plays a major role that lead to path breaking discoveries in physics. Many times these intuitive ideas become so dominate that they prompt the experimenters   to tamper with their result. Let us discuss few famous examples here.

The dictionary definition and notion of Kent for intuition are, to large extent, practically adopted by practitioners of physics and astronomy. According to oxford dictionary intuition is the ability to understand something immediately without the need for conscious reasoning. The Kantian view of intuition is ¹“a non-logical mental form of representation, one that serves partly to render them concrete.” Physics practitioners create mental form of ideas based on the observational data that remains unexplained. Although the idea occurs immediately, the scientists keep thinking them for a long time. The concretization is realized by expressing the ideas in mathematical form that has predictive capability.

Formulation of Newton’s law of gravity, uncertainty principle in quantum mechanics, General Theory of Relativity and theoretical prediction of the existence solar wind are among few examples of result of intuition.

(1) Newton’s law of Universal Gravitation states that the gravitational force F is an attractive force that a body of mass m1 exerts on mass m2, such that F = G (m1 x m2)/r², where G is universal constant of gravitation. The force depends on both mass m1 and m2. The formula could have been F = G (m1+m2)/r², which would have been wrong. Here, Newton’s intuition guided possibly by Galileo’s experiment would lead to correct formulation. Galileo’s “Falling Body” experiment from Tower of Pisa showed that all bodies arrive at the surface of earth with same acceleration called “acceleration due to gravity”, which is 9.806 meters per second², which is the numerical value of (G x M/r²), where M is the mass of earth. So, without air resistance a hammer and a feather would fall at the same time that was observed on moon. The following simple mathematical analysis shows how Newton could have arrived at the correct formula.

 Newton’s second law of motion show that the force F = m x a, where “a” is acceleration. Let us assume the Universal Law of gravitation is that F = G (m1 + m2)/r². Here we have two definitions of force, which must be equivalent.

Equating the right hand side quantities of the two expressions for the force, we get,

m2 x a = G (m1 + m2)/r². m2 is the mass of apple.

If m1 is the mass of earth and m2 is mass of apple, in the above expression

m1 + m2 » m1, m2 being negligible.

That result: a = G m1 / (r² x m2), implying that large bodies would have smaller acceleration compared to smaller bodies, contrary to the Galileo’s experimental result.

By using m1 x m2, we get a = G m1 / (r²), where the acceleration “a” is independent of the mass of falling body, consistent with the observed experiment.

(2) The quantum physics or quantum mechanics was developed with a number of ideas that were proposed by physicists guided by intuition. Among them the most famous one is the Uncertainty Principle, which essentially comes from the idea that no measurement is possible with out disturbance. When we prepare to measure the position of a tiny object such as an electron, by shining light on it we shall move and change the position. So, it is impossible to measure the position and velocity (more precisely momentum) accurately at the same time. Although the “Uncertainty Principle” is being proved mathematically in the modern time, its effect was observed early in the shape of spectral lines and existence of electron degeneracy pressure of dying sun-like stars.

(3) The General Theory of Relativity is another shining example of scientific advancement guided by intuition. While proposing the Universal Law of Gravitation, Sir Isac Newton was uncomfortable with the proposition of “action at a distance” as existence of a force without mediator. The unexplained experimental result existed at the time was extra advancement of mercury’s perihelion position and a host of mathematical tools. Instead of an incremental correction to Newton’s theory, Einstein proposed space-time geometry that is shaped due to the presence of matter and energy in an elegant mathematical formulation. It was so nice that he said, he would be sorry for the God, if it were wrong!! The new General Theory of Relativity not only explained the existing results consistent with Newton’s Law, it predicted bending of light in the vicinity of massive objects among other things that were verified subsequently.

(4) Finally, the story of Solar Wind. For a long time two observations were prominently existed. One: All photographs of the sun during the total solar eclipse showed the existence of a white light corona irrespective of its activity phase. Two: All comets showed the existence of a tail pointing away from the sun, irrespective of the position of the comet in heliosphere. These two observations showed that there must be a continuous wind existing perennially originating from the sun and blowing outward. Eugene Parker, from Chicago University, proved this using the known plasma physics in 1958, which was detected by space born instruments in early 1960s.

Often, while working in the frontiers of science, it is not easy to be guided purely by the observed facts or “data” that overcome one’s own prejudices, as selecting them may be tricky. This was vividly evident in the famous ²“great debate” between Curtis and Shapley in 1920 to decide the structure of our galaxy and nature of spiral nebular (which were newly discovered at that time). They selected the data to make their point in the debate. Curtis was right to argue that the spiral nebulae are external galaxies, while Shapley was correct to argue for the fact that the sun does not reside in the center of our galaxy.

¹Falkenburg, B., 2006, “Functions of Intuition in Quantum Physics”, Intuition and the Axiomatic Methods, E. Carson and R. Huber (eds), Springer, The Netherlands, 267-292.

²Trimble, V., 1995, The 1920 Shapley-Curtis Discussion: Background, Issues and Aftermath, Pub. Astron. Soc. Pac., 107, 1133-1144.

Empirical Facts and Scientific Results - Part II Understanding Atom and Light

These Blogs are based on the lectures for a mini course on "Scientific Method for Non-Scientists".

Empirical Facts and Scientific Results - Part II

Understanding Atom and Light

Debi Prasad Choudhary

Los Angeles

During my student days, I listened to Professor Chandrasekhar saying, the triumph of 20^th century science is that we are able to understand the tiniest objects atoms and giant objects stars with the same set of physical laws. Yet, one hundred ago structure and composition of atoms were mostly unknown. Let us explore how we came this long way. The story of atoms and light is intertwined and gives an excellent insight of scientific processes leading to extraordinary outcome.

The rainbow is dispersed sunlight that contains all visible colors from violet to red continuously with out gap. When we observe similar dispersed light from a fluorescent lamp, we notice gap between the colors. Of course, a highly dispersed sunlight also show gap. The gap in the dispersed light was a mystery in early days of physics about one hundred ago.  In fact, those days famous astronomer Joseph Fraunhofer from Germany, who discovered gaps in solar spectrum conjectured that light does not exist at the colors that show gap!! The fluorescent light contains mercury atoms that get excited through discharge and produce light. Hydrogen atom with a single proton produced light at systematic set of discrete wavelengths (or roughly speaking color) that became key to develop atomic model.

There was another important result in the beginning of 20^th century. In 1909 Ernest Rutherford at the Physical Laboratories of the University of Manchester conducted an experiment to observe the scattering pattern of positively charged particles when bombarded on to a thin foil of gold of thickness 0.00004 cm. The result was that while most particles passed through the foil, one in 20,000 of the particles bounced back. This is possible only if most of the gold atom was empty with a concentrated mass at the center. This experiment played a crucial role in developing current model of atoms.

Niels Bohr, one of the finest minds of 20^th century physics, utilized discrete emission from an atom and results from Rutherford experiment to propose an atomic model that may illustrate commonly used scientific method. Atoms are neutral, so the positively charged nucleus must be accompanied by negatively charged electron. They cannot remain stationary due to the effect of Coulomb force that is attractive. If the electrons move around the nucleus, according to classical electromagnetism, the electrons would loose energy by radiation and eventually fall into the nucleus. Considering the known physics at the time, Bohr in 1913 proposed that electrons orbit the atomic nucleus in discrete stable orbits and do not radiate as long as they remain in the orbit. They gain or loose energy by jumping from one orbit to the other. This is the reason for emission of spectral lines in specific wavelengths (or color) and removal of light from solar spectrum in selected wavelengths due to gaining of energy in the orbit of selected atoms in solar atmosphere. This scientific model explained a number of observations known at the time but had several limitations. It reproduced the spectrum of hydrogen atom successfully, but failed to explain the spectra of larger atoms such as mercury, sodium or Argon and when they emit in a magnetized environment. It laid the foundation for the development of sophisticated version of quantum theory by Heisenberg and Schrodinger. Here, it must be pointed out that the scientific models explain the data for which they are developed and not the final word in the subject. They have scope for constant refinement and development, as more information becomes available.  

At this time, discrete nature of light was already known through photoelectric effect.  The violet light is of smaller wavelength compared to the red light. The violet to red is only a part of vast spectrum of electromagnetic radiation that is light. In photoelectric effect, it was observed that free electrons come out when the surface of a metal plate is illuminated by light. For a given material, the ejection of electrons did not depend on the intensity but wavelength of light. Einstein explained the phenomena by proposing quantum nature of light for which he received Noble Prize. If the wavelength is lower, the light quanta carried more energy, which resulted in electrons with higher velocity or kinetic energy. Quantum nature of light became a natural consequence of light in the Atomic model of Niels Bohr. He said, "Obviously, we get in this way the same expression for the kinetic energy of an electron ejected from an atom by photoelectric effect as that deduced by Einstein." This is another consequence of great scientific theory that encamps vast related phenomena to explain them in a unique fashion.

The fully-grown quantum theory (quantum mechanics) not only explained observed spectra and photoelectric effect, it was used to invent nuclear reaction leading to bomb and source of energy in the interior of the stars. In the center of a star, the pressure of overlying material become so huge that hydrogen atoms are heated to very high temperatures. They come very close and fuse to produce Helium and energy that is released as the light that we observe. The outflowing energy produce radiation pressure that balance inward material pressure leading to stability of stars. When, the internal nuclear combustion halts, the star collapses. For a sun like star this collapse is stopped by “electron degeneracy pressure”, which is also a consequence of quantum theory. One of the founding principles of quantum theory is known as “uncertainty principle”. According to this principle if electron is confined to a very small area, its velocity increases sharply (more precisely velocity x mass). The compressed star confines electron to such a small volume that the fast moving electrons generate enough pressure to stop further collapse for the stars whose mass does not exceed 1.2 times the mass of the sun. This is known as Chandresekhar limit. If the cores of the star exceed this limit they become a ball of neutron (or neutral star) or a blackhole that collapse endless. So the stability of the gigantic objects such as the stars and the stability of tiny particles atoms are understood using the same set of physical laws.

Each time, science is practiced to answer a well-defined precise question. Most basic assumptions are usually carefully designed such that they are not inconsistent with the experimental results. So, if a question is unanswerable with the contemporary science, it is not because the scientific method is incapable, it is because the tools to handle complex questions are not ready yet. Remember, one day we did not know the structure and composition of atoms, yet today we use them to understand the stars and obtain pretty pictures of our self and our loved ones!!

Empirical Facts and Scientific Results - Part I Understanding Gravity: Kepler, Newton and Einstein

These Blogs are based on the lectures for a mini course on "Scientific Method for Non-Scientists".

Empirical Facts and Scientific Results - Part I

Understanding Gravity: Kepler, Newton and Einstein

Debi Prasad Choudhary

Los Angeles

Science originates in human mind. It may not be easy to learn what propels mind to consider objects, a profound question that was posed in a great ancient Indian text known as Kenopnished. But, science has achieved many great things in about past 400 years that has improved our living conditions. Only in last ten years, we can reach our destination guided by a talking gadgets and no longer have to carry a map. We can see our loved ones at far away places and talk to them as if sitting in the next chair. We can locate the center of our galaxy and detect what happened soon after the universe was born. All these achievements make us think that there is something profound about science and the way scientists think. Many advocate that scientific thinking; temperament and the method are somewhat superior to all other ways of thinking. Being a practitioner of science for more than past 30 years, people ask me about the scientific method and seek justification and approval of their beliefs from “science”. My response has been random and non-scientific!! In these blogs, I address the issues related to scientific method, its limitations and justification of other methods of human endeavor. Before considering scientific method, let us learn some concrete example of great scientific achievements. I discuss understanding gravity in past about 400 years in this blog. This is an illustration of practicing science through observation of natural phenomena.

Johannes Kepler lived in early 16^th century when understanding the position of earth in the context of rest of the objects in the sky was of great concern, since it decided the power for a class of individuals. Is the earth center of the universe and govern its affairs through few individuals who have direct access to the creator? If that is so than rest of the human being should obey and serve these chosen ones. This question can be addressed by studying the motion of heavenly objects. There are three types of objects in the sky, which rise in the east and set in the west following a definite path. The stars describe simplest sky path. They appear four minutes late every day at the same location in the east sky and many of them seem to circle around a bright star in northern sky, called pole star or “Dhrub Tara” (Constant star). Some of them appear in the east and set in the west and some do not set by the morning. But, all of them repeat the same pattern annually. This pattern is however, not the same for an observer in the southern hemisphere, living say, in Sydney, Australia or Rio De Janeiro in Brazil, where there is no equivalence of a pole star.  As, most of the ancient astronomy was developed in the northern hemisphere, let is confine our story to northern sky for now. The other types of bright objects in the sky are the planets, which appear as non-blinking stars. The background stellar pattern around them change every day. They do not appear in the same location of the sky, although march in a narrow strip from east to west and also known as “wondering stars”.  The sun and the moon are very bright objects, which repeat their sky path in which planets move on annual basis.

About 600 ago, we did not understand the motions of all these objects in the sky in a comprehensive unified model. People thought, stars, planets, moon and sun revolve around the earth in which our Gods and we live. They invented complex geometrical models to describe these motions and predict their path with some success. For the first time, Nicolaus Copernicus of Poland proposed in 1514 that universe consists of eight spheres at the center of which resides the sun and not earth. The outer sphere contains motionless stars and the planets revolve in fixed spheres. Moon revolves around the earth on a sphere. Even though the concept or the idea was revolutionary that interested the Pope of the time, it had little practical consequence because of the basic assumption of circular orbit of the planets around the sun. Its predictive capacity (for the occurrence of eclipse for example) was limited and similar to the geocentric model. Copernicus considered circular orbits, since these are perfect geometrical shapes and did not have compelling reason for any other geometrical path.

About one hundred years later in about 1623 Johannes Kepler, a German Astronomer used accurate positional measurements of planets in the sky to devise laws that described their motion. He said in first two laws that the planets moves around the sun in elliptical and not in circular orbits in such a way that in equal time, equal area of ellipse is covered. As the sun occupies one of the focus of the eclipse, when the planet is nearer to sun it moves faster. The third law related the period of the planets with their distance. Of course there were other observations such as the phase of the planet Venus that also showed that the planets move around the sun. The introduction of elliptical orbit was crucial as it improved the predictability of the model considerably and offered a clear competitive choice to the geocentric model. Although these laws had profound impact by enhancing confidence on heliocentric model of the universe, they were confined to the planets of the solar system alone and did not have the capability of generalized application. The laws were based on purely empirical evidence of the data provided by Tycho Brahe.

The Kepler’s laws found robust foundation of physics after about 50 fifty years later when Sir Isac Newton showed that the motion of any two bodies with masses m1 and m2 separated by a distance r are governed by central forces F = G (m1 X m2)/r², where G is called gravitational constant (numerically: 6.67384 × 10^-11 m³ kg^-1 s^-2). Both the bodies (objects) would move around a central point, situated near the heavier mass, in elliptical orbits. In case of the solar system, the planets do not move around the sun, instead, the sun and planets move around a common point that is situated near the surface of the sun (not at the center of the sun). The Newton’s law of gravitation defined the force F in a quantitative manner that can be used to predict the orbit of any two bodies with masses and led to several new discoveries. We now know why the Kepler’s laws work. Using the Newtonian version of Kepler’s laws, faint and compact White Dwarf stars near bright stars and supermassive blackhole at the center of our galaxy were discovered. We use these laws to launch geostationary communication satellites for navigation. The scope and utility of data based empirical Kepler’s laws were enhanced by using the physics base that treated the planets and stars as simple matter that interact through a force called gravity. This scientific method of extracting systematics of a set of observations (data) and trying to find the underlying physical cause became useful when they provide scope to predict new phenomena to test their limitations.

Finding the common properties of similar phenomena under different situations and understanding them with a simple predictive model central to scientific method. The other aspect is the quest for “beautiful” and “elegant” mathematical explanation of observed phenomena. The General Theory of Relativity of Albert Einstein illustrates such an example. Newtonian mathematical approach is based on observations of experimental results, in which hypothesis are unnecessary. In fact Newton states that “Hypotheses non fingo (I frame no hypotheses). In 300 hundred years after Newton, several conceptual limitations of his theory was encountered as they were applied to study the dynamics of complex and sophisticated systems, chief among them being absence of inertial frame. This is when Einstein’s imaginative approach produced one of the most beautiful descriptions of the world. Einstein states, “Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.” Einstein proposed that mass and energy shape the space-time geometry, which in turn governs their motion. The consequence of this consideration is that the path of light deviates from the straight line while passing in the vicinity of massive objects, which is now clearly observed. We must note here that there was hardly any need for such consideration from experimental side for Einstein to think in this manner. It is the intuitive generousness that led him to this great discovery.  

Over centuries, man asks questions about its surroundings, some of which are easy and some difficult. Attempting to answer them through generalization of observed results and extending their scope through creative imagination is a vital aspect of scientific method that resulted in a series of discoveries enriching our lives and brought us from caves to modern comfort. The important thing is that any new scientific theory or model must be able to explain the already observed phenomena and predict new results that can be used to test them. The later is an important aspect, absence of which makes a theory unscientific.