The story of photographic plates: NGC 1851

Unravelling the hidden data from the archival photographic plates of globular cluster- NGC 1851
This work got published in the ‘BASE Line’ a quarterly bulletin of JNP, Bangalore.



(This is a scanned copy of the BASE Line.  Full copy of the bulletin can be downloaded here )


Jawaharlal Nehru Planplanetarium Bangalore (JNP)

Vision and Mission 


  • To popularise science amongst general public
  • Non-formal science education,
  • To train students to take up science as a career.

BASE has established a Science Centre in the Planetarium which has become a nucleus for non-formal science education at all levels. The activities of the Science Centre and the Planetarium have made BASE a unique institution for the dissemination of science. A Science Park has been developed in the premises of the Planetarium.

Science popularisation activities of  BASE viz., sky-theatre shows, monthly astronomy lectures, monthly science movies attract over two lakh visitors every year.

Our science education activities viz., Research Education Advancement Programme (REAP), Interactive Week-end Sessions for school children, Summer Programmes, Science Exhibitions and Workshops attract thousands of students every year. Over 35 students from BASE have got admission for Ph.D. courses in premier research institutes in India and abroad. They include Raman Research Institute, Indian Institute of Science, Wild Life Research Institute, Oxford University, Michigan State University, Delft Institute, State University New York, Buffalo, University of Florida, Cornell University.

JNP Publications

JNP Website

JNP Address
Jawaharlal Nehru Planetarium
Bangalore Association for Science Education,
Sri T. Choudaiah Road, High Grounds,
Bangalore – 560 001
Land Mark: Opp. Indira Gandhi Musical Fountain, Near Raj Bhavan.

Viswa Keerthy S


‘YoU(r)’niversal Law!

Newton’s ‘Universal’ Law of Gravitation portrayed in an article -theguardian

Once there was a conversation on the topic – What is “Universal Law”? with three persons whom I know very well, here are there views… (there actual WhatsApp conversation).

First Person : Is coulomb’s law universal law …. ?

Second Person: Vo nice… will think on this… it is difficult to term a law as universal.

Second Person: for me the concern is the constant present in the coulomb’s law….

Second Person: Change the equal sign to nearly equal or the force is proportional to the product of two charges by the square of the distance between them… is more or less Universal Law….

Second Person: And I also do have a feeling that no law is universal law….

Second Person: it is nearly universal but not fully universal!!

First Person : Can u get the criterion to call a law universal

Second Person: the only condition I believe is that, it should be valid at all points in the universe…

Second Person: If this is a condition… Just a single law cannot become universal… (up to the physics that we know today)

First Person: What do u mean by just a single law

Second Person: one law cannot be valid at all places… anta

Second Person: Even Newton’s Universal Law of Gravitation is also not a universal law… the name still sticks to it.


First Person : Howda…. (Is it?)

First Person : Elli valid alla adu? (Where it is not valid?)

Second Person: Mercury ge valid agalla… (the law is not valid for mercury…)

Second Person: GPS system ge valid agalla… (it is not a suitable law for GPS…)

First Person : Every 2 particles having mass should obey

Second Person: Yes…

First Person : Mercury ge yake aagalla (Why the law is not valid for mercury?)

Second Person: I don’t remember where I read this…

Second Person: it says like this…

First Person: the light moving near the star bends due to SR or GR what ever?  But the claim is that the star attracts (not a suitable word)  light particles and in turn light also attracts the star at a very negligible force (which is not zero but negligible).  According to Newton’s law how can light attract star, it does not have mass (rest mass!!)

Second Person: But these things are accounted for accurate measurement of many things… which is not the direct consequence of Newton’s Law!!

First Person: The concept is different from Newton’s law ashte

Second Person: Mercury has a special kind of motion called “Precision of its Orbit” which is not explained by Newton’s law.

Second Person: Yes, that puts a question on Mass?  Does mass is the main source of gravity in the nature (which is true with newton’s law)

First Person : According to khan academy lecture precession is boz of sun earth interaction

Second Person: interaction through Gravity…

Second Person: if newton’s law talks about Gravity, then it should explain… these interactions… why it fails?

First Person : Yes

Second Person: btw this is only for Mercury…

First Person : Y not

Second Person: Uranus and Neptune were discovered because of the power of Newton’s Law….

Second Person: what I am trying to say is that, gravity is not just the way Newton’s Law define.  It may be true at some places but not at all places… and Newton’s law does not give full picture of it… So it is not a universal law (that is why I said “Universal Law” should not be restricted to just one law)

First Person : G is called universal constant … law is valid at every place

Second Person: humm,

Second Person: What is the source of G?

First Person: Cavendish experiment proof

Second Person: Newton’s law is not just G.  It is a constant number that is present in our universe.  But the value of G does not talk about the nature of gravity… that is spoken by other parameters in the newtons law… which is not always true at all points in the space…

First Person : Do u mean (M)(m)/ r square.  Is not true at certain places ?

Second Person: Yes, it is nearly true but not always… Once C. Sivram sir took a beautiful class in M.Sc.

Second Person: That is why we have General Theory of Relativity…

Second Person: Combination of both Newton’s Law and GR could be universal (if we really need to use this word)….

First Person: I’m stunned. .. no words

Second Person: Yes, that is Nature!!

First Person : Students ge hogi Newton’s law universal alla antha helbeka

Second Person: Interesting part is Kepler defines the motion of planet without using Gravity…. It perfectly fits..  Later newton comes and gives gravitational concept… Kepler did not even know about this Gravity.

Second Person: In fact nothing is universal!! anta ankondiddini… (In fact, I think nothing is universal)


Third Person : Even i think so…that, no law is universal “YET”

Second Person: Yet….? What next?

Third Person : May be in future we can get a universal law…

Second Person: Yes…

So, what is your thoughts on it?  Reply to this article.
I mean ‘YoU(r)’niversal Law!!

Viswa Keerthy S

Elusive Particle of the Universe

Hi, welcome to you for the year of light and welcome to you for this interesting lecture.

Celebrating IYL 2015

Yes, we are talking about light, the light which is responsible for the diverse life on Earth and spreads in the unimaginable universe.  In the last lecture we spoke about the first light from the Big Bang called CMBR.  But in this lecture I don’t directly talk about light.  Instead I talk about atoms!!

Atoms are the building blocks of matter.  We have more number of atoms in our eye than the total number of stars in a galaxy.  This is true with any object which is of the size of an eye.  In principle we humans are all collection of atoms that have different names!  The matter which surrounds us is also a collection of atoms.  Suppose if I am drinking water from a glass.  If you shoot this in a video-camera which can only detect atoms regardless of their physical size, shape, and features, you can see that some arrangement of atoms drinking the same atoms which are in different arrangement.  This means that, you can form infinite number of structures by arranging atoms.  That is what the nature is doing from all these billions of billions years and it continuous do it in future also.  So, if you look at animals, birds, plants, humans, mountains, earth, stars and galaxies all these are just arrangement of atoms.

Image 4
Arrangement of atoms forms different structures. (Living and Non Living Things)

So it is important to study about atom.  Until the beginning of 20th century, scientist thought that atom is an indivisible particle of the universe and the fundamental particle of all the objects.  Later many observations and sensitive measurements by the 20th century scientist proved that atom is divisible.  Today we know that atom is made up of proton, neutron and electrons.  Protons and neutrons make up the nucleus which concentrates most of the atoms mass while the electrons revolve around the nucleus.  If I have to give you the feel of an atom or how big an atom is; imagine like this, consider this room (Auditorium) is of the size of an atom and this tennis ball (author is holding tennis ball) is a nucleus, than the smallest dust grain that you can find in this room is an electron!  This means atom mostly contains an empty space!  All the mass is concentrated in the nucleus.  This is a distinctive sketch of an atom.  But you might ask me a question… Do all atoms show the same characteristics?  The answer is no.  Atom with some fixed number of protons, neutrons and electrons have some physical and chemical characters.  But if you change the number of constituent particles of an atom, the characteristics also changes.  This means that if you change the number of electrons in an atom it exhibit different characteristics than the previous one.  Depending on the number of electrons in an atom a specific name is given to them, like hydrogen which has one electron, helium which has 2 electrons and so on… These are called elements.  These are arranged according to the ascending order of the number of electrons in their atoms.  This is called Periodic Table.  This table makes us to easily identify the element which has a specific character depending on its electron number.  This is about atom, and its constituent particles and their arrangement and how there characteristics changes.  But why am I talking about this, instead of light!

Yes, I will talk about light, but for a while let us go back to 1930.  Wolfgang Pauli an Astrian physicist was trying solve the mysterious violation of law of conservation of energy in process called Beta Decay.  I know all of you know about law of conservation of energy, in simple words the law says, energy can neither be created nor be destroyed.  It can only transfer from one form to another form.  And also the energy of the entire universe is constant.   In a given process the energy before the process and after the process should be equal.  No room for violation of this law in nature.  While doing math’s we may do errors in calculating the energies, but nature do not do any error.  It never violets the law of conservation of energy!  But something strange was happening with beta decay.  To know this let us learn about beta decay.  Since we know about atom, it is very easy to understand this process.  In certain elements the nucleus which contains protons and neutrons becomes unstable due to the more number of neutrons than the protons.  If something is unstable it has to give out or it has to accept something in order to attain stable position.  Here we have only protons and neutrons in the nucleus.  So, what happens to this unstable nucleus?  Yes, an extra neutron in the nucleus decays into proton and in this process an electron is emitted out of the nucleus as shown by the below nuclear reaction. (The elements which shows this behavior is called Radioactive Elements and the process is called Radioactivity). This process is called beta decay.  (Beta particle = Electron).  This is an observable process and the experiments have confirmed this nuclear reaction.  But what is the strangeness about this nuclear reaction?  You might be surprised to hear this; this nuclear reaction is actually violating the law of conservation of energy!  But the question is HOW?

n -> p + e

If you equate the energies in beta decay process, you will see that the total energy of the emitted particle is less than the energy of reactants (for now consider it as reactants).  Let me explain this… In beta decay process an extra neutron in the nucleus decays into proton and stays inside the nucleus.  But an electron ejects out from the nucleus and this electron does not belong to orbital electrons, because it is created in the nucleus and emitted out.  But the amount of energy that electron is taking out from the nucleus is less compared to the energy used in creation of the electron.  This tells us some energy is missing in this process.  When we do the experiment, there is no signature of any other particle taking the missing energy. Then where is the missing energy?  This is the question that haunted many scientists during the twentieth century.  So what do you conclude based on our experiment?  Is nature violating the law of conservation of energy or our calculations are wrong?

Pauli worked extensively on this problem of missing energy in beta decay and finally arrived at one conclusion.  He believed that the universe is governed by the order of natural laws.  And he had firm believes that nature does not violates these laws.  More importantly he also believed that his calculations are correct.  He said nature is not violating law of conservation of energy.  The missing energy in the beta decay is transmitted through a particle called ‘Neutrino’ which has zero mass but has the energy which corresponds to the missing energy!  He wrote down all the mathematical calculation to prove the existence of this particle which he called Neutrino and published the paper.  But many scientists did not believe Pauli and went on claiming that, this kind of particle does not exist.  But Pauli who was theoretical physicist, I mean the one who do only math and calculation to give the theory of nature had solid-believe on his theory.  I should say he trusted his calculations so much that, he always said this particle; I mean the neutrino should exist in our nature.  This is the beauty of understanding the nature.  This is where we should appreciate our language called maths and equations.  The numbers and equations hide the unseen exquisiteness of nature.

n -> p + e + nubar

Finally the beauty of Pauli’s calculation unfolded in the year 1956, when two physicist Frederick Reines and Clyde Cowan announced that they have indeed detected neutrino’s in beta decay process predicted by Pauli.  It nearly took 16 years to find the existence of the particle predicted by the great physicist Pauli.  But you know what, nearly trillions of trillions of trillions neutrinos have passed through your body while listening to this lecture.  For every minute billions of neutrino is passing your body.  The earth is in the shower of neutrinos from the sun, stars and galaxies endlessly.

Today I am here to talk about neutrinos.  When Pauli predicted this particle, he said it has energy but rest mass of the particle is zero, which means these particles never come to rest!!  So, how do we detect this particle?

Sir, I have question.
Go Ahead (Author)
Sir, Why do we need to detect neutrinos?  Should we detect them only to explain beta decay or is there any other use from them?

Very good question.  Beta decay problem is over, it is now confirmed that neutrinos are emitted from the nucleus and law of conservation of energy is successfully explained with this particle.  I will reframe your question like this; why do we need to detect neutrinos on a large scale? Does it give any information to us?  The answer is yes and let me give you one such example.  Let us talk about Sun for a while; the thermonuclear reaction happening at the core is powering sun’s total energy.  During this reaction photon (particles of light), neutrinos and other particles are emitted.  The light that warms the surface of the earth as well as you and me has come from the photosphere of the sun.  Photosphere is the visible disc of the sun.  As we all know that light contains photons.  These photons are generated at the core of the Sun.  It takes billions of years for a photon to reach to the surface of the photosphere; from there the photon takes only 8 minutes to travel to the earth.  So the photon which is warming you right now has left the sun’s interiors billions of years ago.  Yes….. Absolutely amazing right!  If you study this light you will be actually studying the sun’s interior which is present some billions of years ago.  So you cannot study real time sun’s core in the visible light.  But on the other hand the neutrinos which are created at the sun’s core travel to the earth in just 8 minutes.  This is because neutrinos do not interact (very very less interaction) with matter.  They just pass through it.  But photon suffers trillions of collisions with the matter spending billions of years inside the sun before emerging out of the photosphere.  So detecting these solar neutrinos is very helpful in monitoring real time sun’s core.  Not only Sun in all the high energetic explosions (Supernovae and other) that happens in our universe emits neutrinos and detecting them will give us clear picture of these events as well as our universe.

How do we detect them?  As I said neutrinos interaction with matter is very less.  They can pass through humans, buildings and even mountains!!  That is why they are called as most elusive particles of the universe.  But if we detect them we get a lot of information about our universe.  So here it is an astronomical observatory built half a mile down the earth.  This is Super-Kamikonde Neutrino Observatory built under Mt Ikenoyama at Japan.  This is a human eye to watch supernovae in our milky way galaxy.

Image 1
Super-Kamikonde Neutrino Observatory (Screen grab from the documentary Cosmos hosted by Neil deGrasse Tyson)
Image 2
Super-Kamikonde Neutrino Observatory (Screen grab from the documentary Cosmos hosted by Neil deGrasse Tyson)

The observatory is built underneath the mountain.  This is because the instrument which detects the neutrinos is very sensitive.  Apart from neutrinos there are other elementary particles reaching earth.  If we have not shielded our instruments then the detector will pick up the signs of unwanted particles.  How to shield these particles? Yes, go underneath the mountain; let nature itself shield these particles (Most other particles can interact with matter).  Most of the neutrino observatories are built in the abanded mining places.   Since neutrinos don’t interact with matter, they just pass through the mountain and to the detector.  And because of zero interaction with matter for billions of years, they have the information of past!  If you detect them you can actually get oldest of old information regarding our universe.  Detecting even a single neutrino requires lot of big observatories like this and lot of patience because of its elusive nature.

In this observatory, 50000 tones of distilled water are stored and it is surrounded with scintillating tubes which detects the minute flash of light.  But how do you get this flash of light in distilled water?  In a minute trillions of trillions of neutrinos are passing through this huge detector.  Suppose if one neutrino interacts with the nucleus of water molecule, an electron is emitted.  This electron is detected by the very sensitive scintillating tubes by producing a flash of light.  Each flash of light can signifies the presence of neutron in the detector.  If the activity is more in outer space, I mean if there was a supernova in our galaxy, then flash of light increases indicating the presence of more neutrinos.  This has been observed during the Supernovae-1987A in the year 1987.

Image 3
Astrophysicist Neil deGrasse Tyson having boat journey inside the detector. (Screen grab from the documentary Cosmos hosted by Neil deGrasse Tyson)

A flash of light is used to detect one of the most elusive particles of the universe which hides rich information about our home.  It is again the light that is doing our work!

Happy International Year of Light.
Thanks a lot for listening to me, that’s it for today.
Have a great evening.

Image Credits:
First Image: Google Images
Second, Third and Fourth Images: Screen grab from the documentary Cosmos hosted by Astrophysicist Neil deGrasse Tyson

Year 2015 is celebrated as International Year of Light and Light Based Technology by UN as a global event.  This year mark the 150th anniversary of Maxwell’s Equations by James Clerk Maxwell, the man who unfolded the secret of nature and answered what light is made up of. 

More Information about IYL 2015
UN Anniversaries
IYL – 2015 Home Page
IYL – 2015 Blog

Upcoming Topics for IYL 2015

  • Biological Industry – Photosynthesis
  • Principe, Africa – 1919 TSE
  • Copy of Earth – Extraterrestrial Planet
  • ದೀಪವು ನಿನ್ನದೆ ಗಾಳಿಯು ನಿನ್ನದೆ ಆರದಿರಲಿ ಬೆಳಕು
  • Let there be light – Newton, Maxwell, Hertz and Einstein

Viswa Keerthy S

First Light – CMBR

Celebrating IYL 2015

     If you look at the modern periodic table you will find hundred and eighteen elements listed in it. Out of this, ninety four elements occur naturally.  All these elements can be found on Earth (exceptions are there).  Elements are building block of things that you see around you.  Whether it’s a human, animal, tree, building, roads, bridges, monuments, mountains, etc, everything is made up of elements.  But the question that comes to our mind is who brought all these elements on the Earth?  How are they formed?  The answer is… all these elements are formed inside a star.  Yes, in a sense, everything that you see around is cooked inside a star!  Richard Feynman, a famous physicist once said that, the stuff which we are made was once cooked in a star and spit out.

      The entire universe comprises trillions of trillions stars which cooks the matter that we see around us.  The next question that arises is how do these stars form?  Well, these kinds of questions will go on….. it’s a never ending process. But then, where do we begin?

Yes, we begin at the beginning.
We begin at the Big Bang!

Big Bang
Artist view of Big Bang before the explosion.

     The universe which includes stars, galaxies, nebulae etc. is expanding for billions of years.  If you look back, somewhere in the past there must exist a time where the entire universe is concentrated in a point of high density (infinite density).  According to the accepted theory, this high density state of a point, exploded violently, creating the universe that we see today.  This is the Big Bang theory proposed by Edwin Hubble in the year 1929.  The explosion that we consider in Big Bang is not at all a violent explosion, in fact it is one of the silent explosions that you can ever think of and it is neither big nor bang!  This is just a name given to the theory.  The reason is this, the space, time, sound, matter, elements and more importantly the light that we feel and experience today was created after Big Bang!  Big Bang is just an expansion of a point of infinite density, nothing more that.  But then, how do we verify this theory?

     If this kind of an expansion has happened in the past, then we must be able to detect, outer surface of the expanding sphere which contains the information of big bang in the form of light.  According to the theory, this sphere of light should uniformly exist all over the space. In a sense we have to detect the first light from the big bang.  This is called background radiation of the Big Bang.  If we succeed, it confirms the theory Big Bang.

   In the year, 1960 two astrophysics namely Dickey and Pebbles were working on the challenge of finding background radiation of the Big Bang.  They came to the conclusion that, since universe is expanding from billions of years, the energy of the photons of background radiation must be less because of the expansion in space.  (Expanding Universe:  The space and time fabric between the galaxies expand.  The light or the photon which travels in this fabric also expands.  When it expands the energy of the photon becomes less – this is predicted by Einstein’s General Theory of Relativity) When they did the calculation by using Wien’s Displacement law, they found that photon’s energy lies in the microwave region of light.
Few miles away from this group of scientist there were two more researchers from Bell Laboratory namely Penzias and Wilson designing the Horn antenna for radio astronomy.  They were trying to remove the background noise in the antenna which is detected by the detector.  No matter how much they tried they were unable to remove the background noise even-though they replaced the detector for many times.  Interestingly the detector was detecting the noise in all the direction and at all times of the day.  After their unsuccessful attempt of trying to remove this noise, they come to the conclusion that, this signal is not a noise, it is actually coming from outer space.

     Later it turned out that the noise of Penzias and Wilson’s horn antennae was actually the background radiation of Big Bang that Dickey and Pebbles were searching for!  Yes, it was an accidental discovery by two researchers from Bell Laboratory who have no idea about background radiation.  All they did was they tuned their antennae to receive a microwave radiation.  The detector was detecting first light from the Big Bang but Penzias and Wilson thought it was noise!!  The temperature of the background radiation was 3 kelvin and it was in perfect agreement with the measured value from the theory.  This is famously called as 3 kelvin black body radiation curve or 3 K curve.   Both of them were awarded noble price in physics in the year 1978 for their accidental discovery of Background Radiation.  Press Release from Bell Labs can be seen here. This observation confirms Big Bang theory.  (Big Bang theory is still a debatable theory for other reasons).

Horn Antenna
Penzias and Wilson in front of Horn Antenna

     Today we have some of the sophisticated scientific instruments in the on-board satellites which are revolving around the Earth.  WMAP (Wilkinson Microwave Anisotropy Probe) has mapped the background radiation.  The first light from the Big Bang is here….

CMBR – Cosmic Microwave Background Radiation by WMAP

The Light which is the sole responsible for life on earth was actually began its journey 13.5 billion years ago.

Through light on some atoms for billions of years, eventually you have life!

Image Details:
First Image: International Year of Light and Light Based Applications – 2015 Logo
Second Image: S. Harris Cartoon
Third Image : Bell Labs
Fourth Image:
APOD Images, March 25, 2013
Year 2015 is celebrated as International Year of Light and Light Based Technology by UN as a global event.  This year mark the 150th anniversary of Maxwell’s Equations by James Clerk Maxwell, the man who unfolded the secret of nature and answered what light is made up of. 

More Information about IYL 2015
UN Anniversaries
IYL – 2015 Home Page
IYL – 2015 Blog

Upcoming Topics for IYL 2015

  • Elusive Particles of the Universe
  • Biological Industry – Photosynthesis
  • Principe, Africa – 1919 TSE
  • Copy of Earth – Extraterrestrial Planet
  • ದೀಪವು ನಿನ್ನದೆ ಗಾಳಿಯು ನಿನ್ನದೆ ಆರದಿರಲಿ ಬೆಳಕು
  • Let there be light – Newton, Maxwell, Hertz and Einstein

Viswa Keerthy S


Wavefunction and Max Born

One of the beautiful theories in physics, which is more than hundred years old, is Quantum Mechanics (QM).  In 1900 when Blackbody Curve was satisfactorily explained by Max Planck, Quantum Mechanics saw its birth.  Later many great scientist of 20th century like Einstein, Bohr, Hertz, Heisenberg, Dirac, Schrodinger, Born, de Broglie developed quantum mechanics the way we see it now.  Almost all the people whom I have mentioned above have received Nobel Prize for their work on developing QM.  But to me the important thing is the idea behind the each stage of development in the QM.  Some of the concept and the experimental results were unable to explain with the knowledge of Classical Mechanics which was well developed during that time.  The new ideas and concepts which came up to explain these strange results were led to the development of this field.  Here I want to focus on some ideas/concepts of QM developed by different people and more importantly by a great mathematician and physicist Max Born.

Max Planck was the first person who broke the “continuity” concept of classical mechanics and introduced the “discreteness” in the energy called ‘quanta’ (packets) of energy in order to explain the “Blackbody Curve”.  The formula which he gave was in fact a perfect fit for the observed experimental curve.  His formula for the discrete energy includes the constant h = 6.023X10^-34 Joules, where h is Planck’s constant.  He was awarded Nobel Prize for his work in the year 1918.  Later in 1905 Einstein also came up with similar idea of ‘photon’ (packets of energy) to explain the energy concept in Photoelectric Effect.  The concept of ‘discreteness’ (Einstein called ‘photon’, Planck called ‘quanta’) again fits perfectly for the Photoelectric Effect.  So, it is the idea of quantization principle (discreteness) which led to the satisfactory explanation for all these experimental results.  And Einstein received his Nobel Prize for his work on Photoelectric Effect in 1921.  Another great scientist Neils Bohr who was a student of Rutherford and he was working on the model of an atom.  Rutherford atomic model was not satisfactorily explaining all the observed experimental results.  His student Bohr applied the same ‘quantization principle’ to angular momentum and by using Plank theory he was able to explain all the observed phenomena through his new atomic model.  Again quantization principle perfectly fits the theory.  So, in quantum world every quantity is quantized.  Today we know even space and spin is quantized!  But in classical world this is not at all true, everything looks continuous!  The idea of quantization by different people has led to the development of this unknown world known as ‘quantum world’.

scientist photo copyImage: Max Planck, W Heisenberg, E Schrodinger, Max Born. 

In 1924 another great scientist de Broglie came up with a strange concept that almost all particles which has mass is associated with wave nature with a wavelength of h/mv, where v is the velocity of particle, m is mass and h is Planck’s constant.  This is called Wave-Particle duality, where all particle exhibit both the properties of wave as well as particle.  This was a big blow in the development of QM and its a strange concept when compared to Classical Mechanics.  The theory predicted that if a car (mass m) is moving at a velocity ‘v’ is actually associated with a wave of wavelength ‘h/mv’.  Classically it is impossible for a car to move like wave, but still the theory predicted wave nature of a car and gave the value of wavelength.  But in reality the effect of wave nature in a macroscopic world (mass is large) is very small and can be neglected, which means the car’s wavelength is very small and its wave nature can be neglected!  But when it comes to an electron which has very less mass, the wave nature of an electron magnifies and it can be studied under suitable condition.  The concept of QM is to study the dynamics of these tiny particles such as electrons and elementary particles.  Theory of QM is applicable to almost all particles, but for macroscopic particles the effects are very negligible and it is neglected.  This actually makes QM theory a Universal Theory to some extent.  For predicting the strange (classical sense) theory of wave-particle duality of nature de Broglie was awarded Nobel Prize in 1929.  Meanwhile in 1925 W Heisenberg explained the basic principles of QM through his papers ‘Quantum- Theoretical Mechanics based exclusively on relationships between quantities observable in principle’.  And in the very next year E Schrödinger came up with a different approach to QM through his ‘wave equation’, which is a very famous equation in physics called as ‘Schrodinger Equation’.  In classical mechanics we write the famous Newton’s law as F=ma, where ‘F’ is force applied, ‘m’ is mass of an object and ‘a’ is the acceleration of an object.  By solving this equation for a particular system (ex pendulum) we can get the equations of motion.  Which means the solutions can predict the motion of a system (ex Pendulum) after some time (t).  Newton’s law is actually the foundation to classical mechanics. And this equation holds good for almost all systems classically.  On the other hand in QM the same equation is replaced by ‘Schrodinger Equation’ which is given below.  Compare to Newton’s law, Schrödinger Equation is not so simple and difficult to solve.Equation

Meanwhile in 1927 Heisenberg came up with another law known as ‘Uncertainty Law’.  He said it is impossible to measure the position and momentum (mass x velocity) simultaneously for microscopic particles.  It means we cannot say the position and momentum of particle (ex. electron) at the same time.  This kind of simultaneous measurement is impossible in QM.  But in classical mechanics we can easily say the position of car and its momentum at any point of time simultaneously.  In macroscopic world everything looks simple and obvious, but the same is not true in microscopic world.  This restriction has reveled striking feature of microscopic world (nature) that we cannot pin point where is the electron in a system at a given point of time.  So, the traditional way of writing atomic model (fig a) breaks down and electron never revolve around the nucleus in a circular way as we have learnt in school.  Instead the circular line becomes a disk of width ‘a’ (two dimensional representation) (fig b).  Electron is present in the region of disk, but where in the region is unknown even today. There is a debate that may be we lack the technology of doing experiment and our instruments are incapable of doing such sensitive measurement.  But this is ruled out by scientist!  It is nothing to do with our technology or the sensitivity of instruments, Uncertainty Law is a law in nature! Neither our future technology nor our highly sensitive instruments in future can go beyond this level.  It is just there in the nature, and it magnifies in microscopic level.

model of atom

As I said the Schrödinger equation actually tells the dynamics of the particles (say electron).  It should describe how an electron moves in a given condition (ex. Infinite Square Well Potential).  While expressing this equation Schrodinger assumed that all the required information about the particle (electron) is hidden in the quantity called wavefunction (Ψ). By applying the given condition (given potential) to the equation one should get the value of wavefunction which is normally in complex form.  After obtaining the wavefunction in its form, the required information should be extracted from the wavefunction.  And this wavefuntion is a not a localized function but a spread function!  Uncertainty Law which is present in nature is actually a hidden property of Schrödinger equation and it shows up in the wavefunction as a spread function (not localized like classical mechanics).  But the question is how do we extract the required information about a particle from wavefunction?  Here comes Max Born a mathematician and physicist with his revolutionary approach to QM through Statistical Mechanics in the year 1926 said ‘modulus psi square(IΨ(x,t)I^2) is actually gives the probability of finding the particle at a point x and time t. Which means squaring of modulus of a wavefunction is actually a real quantity not a complex number! (But remember wavefunction is a complex quantity)  And Max Born was the first person to identify this quantity as the ‘probability’ of finding electron at x at time t.  This is called Born’s Statistical Interpritation.    I feel this concept is a revolution in QM, because without this concept we cannot interpret the wavefunction.  The normalization concept which is the direct product of this idea is a very handy tool in handling wavefunction.  I feel the statistical approach is the most significant step in the development of QM.  All credits go to Max Born who identified ‘modulus psi square’ is actually a probability.  Heisenberg and Schrodinger were awarded Nobel Prize in 1932 and 1933 respectively.  Max Born was awarded Nobel Prize on Dec 11, 1954 for his statistical approach to QM, after 29 years of his most important concept.  Coincidentally his Nobel Prize ceremony date was his 72nd birth anniversary (Born: 11 Dec 1882, Died: 5 Jan 1970)! In his Nobel Lectures he began his talk like this ” The work, for which I have had honour to be awarded the Nobel Prize for 1954, contains no discovery of fresh natural phenomenon, but rather the basis for a new mode of thought in regard to natural phenomena.”  What matters more is the way we think on some observed results/phenomenon.  All great scientist have just did that.  If you ask me what is QM, in simple words I can say Quantum Mechanics is just solving Schrodinger Equation.
(Max Born visited Bangalore in the year 1935.  He worked with Sir C V Raman at Indian Institute of Science for six months.)

On an application level QM has wide verity of application.  In a real world application it is applied in Laser, MRI, Quantum Cryptography, Transistor and many more.  It is also applied in the study of Atoms and Molecules, Nuclear Physics, Astrophysics, Solid State Physics and many more.  At some point of time I said QM is a Universal Theory, but still it fails to explain some important concepts.  Even today there is a debate on the fundamental concepts and principles of QM.  It is still not a complete theory even after more than hundred years.  Never the less it is one of the famous theories in Physics.

In the developing stages, the unique ideas by the scientist played a vital role in shaping QM in a proper way.  For student like us the important thing is the ideas behind each successful stage of development in QM or in general Science.  The ideas/concepts which are different from normal thinking can actually change the world totally.  This has actually happened in the history.  When I met my friend Suraj at Bangalore Planetarium, we were discussing about the great scientist and their concepts.  He said “look Einstein is famous for E=mc^2, Stephen Hawking is famous for his chair, Feynman is famous for his teachings, but there are other great scientist with their ideas/concepts, revolutionized the world, but they are not famous among us (to some extant this is true even among science students and teachers).  Everyone tells Faraday, Einstein, Edison, Hawking but nobody remembers Maxwell, Tesla, Born, Dirac, Pauli and many more who are equally important like others.  The reason is we never tell the stories of these great peoples among students.   I feel it is the stories of these great people and their ideas are important to students rather than the confined textbook chapters.

[If you are still interested in quantum mechanics and its development I strongly recommend you to read the preliminary chapters and Nobel Lectures in the book “Quantum Mechanics: Theory and Applications” by A.K. Ghatak and S. Lokanathan.     (S. Lokanathan was my Classical Mechanics teacher in REAP Course at Bangalore Planetarium)].

[I have just shown only four scientist pictures in this article, but all of them are equally important.]

Image credits: Google images.

Viswa Keerthy S

Six Easy Pieces from Feynman

The subject which was called Natural Philosophy during olden days is relatively called Physics in today’s world.  Physics is a study of nature in particular the ‘laws’ of nature.  It means, Physics involves the study of why ‘things’ has to happen the way it is happening and figuring out the law behind it?  What is so special about these laws?  Can we explain everything (I mean the working of nature) with these laws?  For centuries people have struggled with these questions and exhausted their life on searching out the correct laws of nature.  Some of them have succeeded in figuring out.  They are the great persons (Archimides to Stephen Hawking) who revolutionized our understanding about nature.  From last fifty years due to the rapid growth in the field of science and technology, the question we can ask is, have we figured out all the laws of nature?  Can we say how nature works?  The answer is no! We have not yet reached such level of understanding.  We can bravely say we still don’t know many ‘things’ and how it works!  Yet, our small understanding about nature has put all of us to lead privileged life, which none of our ancestors experienced.  Now if you ask, what we have did, and what we have understood about nature, I better show you this book- “Six Easy Pieces Essentials” by Richard P. Feynman.

The book contains six chapters, taken from most famous book in physics “The Feynman Lectures on Physics”.  Six Chapters are Atoms in Motion, Basic Physics, The Relation of Physics to other Science, Conservation of Energy, Theory of Gravitation and Quantum Behavior.  Unlike the great physicist, Feynman was considered as a greatest physicist and teacher of all time.  He has a remarkable talent of explaining most difficult ‘things’ in a very simple way.  This makes him very special among all other scientist.  His legendary lectures at Caltech, now it is called Feynman Lectures, considered as ‘The Bible’ in physics.  And the six chapters which were mentioned above are the selected topics from these books. It’s a popular science book and does not require any knowledge of science to read.  But, if you have interest in science you must read this book.   He explains how each simple observation and some simple experiments have changed our understanding about nature.  It is true that we have revolutionized our level of understanding compare to the Aristotle period or even at the beginning of 20th century.  Yet, we have not fully discovered the entire laws.

The title of the book says “Six Easy Pieces Essentials” in reality these are the six pieces, which are very essential to understand our nature. And Feynman does not make you to understand these topics; instead he explains why these are very important, what is so special about them, in his typical ‘Feynman Style’.  Read the book to get experience yourself.  At last let me ask you this.  By some way all our scientific knowledge is destroyed and only one sentence (Scientific Idea) is to be conveyed to the future generation.  What will you convey in one sentence, which contains nearly all information of our scientific idea? Answer: Read this book!

You can Google it and get E-copy of the book.
For purchase…

-Viswa Keerthy S (21/07/2013)

“Symmetry, Symmetry, Symmetry”

tarasov-this-amazingly-symmetrical-worldWhen we see the word ‘Symmetry’, we used to think vo! It is a topic in elementary particle physics, crystal structures, rotational symmetry, transnational symmetry and other things… full theory, and we feel it’s a boring topic.  Once we decide it’s a boring topic, no matter what happens we never ever even try to look at it.  I feel this is the nature of normal student.  But now, I am here to tell you about a book which is written on “Symmetry”!, believe it or not once you read this book you will surely say, without ‘symmetry’ atom, matter, earth, life, etc,.… nothing would have existed!

      Symmetry is one of the most general properties of nature.  And Symmetry is not restricted to Chemistry, Crystal Structure and Particle Physics.  It can be visualize everywhere in nature.  It can be seen in animals, plants, birds, humans, snowflakes, non living objects… what not! Everywhere you can see symmetry.  In the book “This Amazingly Symmetrical World” the author quotes a sentence said by M Gardner (mathematician and science writer) that “On the earth life started out with spherical symmetry, than branched off in two major directions: the plant world with symmetry similar to that of cone, and animal world with bilateral symmetry.”  Yes it is true! If you see any plant from top, the structure of the plant looks like cone.  The cone structure ensures equal sharing of sun light to all parts.  And all animals do exhibit bilateral symmetry.  Symmetry controls the structures of all living organisms.  Amazing!

     Throughout the book author puts above sentence in this way “Symmetry limits the diversity of structures in nature.”  And he gives many examples of which one of the interesting examples is this one… Many of our science fiction stories portraits that extraterrestrials may look very different than organisms found on earth.  But symmetry tells you, whatever the extraterrestrials looks like, they must exhibit bilateral symmetry.  The reason is our laws of physics are universal in nature.  That is, whatever the planet, the planet will have gravity, and our physics laws works same as it worked here.  And again all our symmetric conservation laws of nature works the same in that world.  If the conditions present in other planet and here is same then, extraterrestrials should exhibit bilateral symmetry.  What fiction stories tell such as, a single eye, and single ear or any wired organisms is not possible just like that.  Symmetry of physics laws restricts those structures.  For example if extraterrestrials has ear, it should have two ears with same size and shape on opposite side.  At the same time it does not mean that symmetry can predict the possible structures in nature; instead it can predict structures which are not possible in nature.  Whatever the topics in which you study symmetry, symmetry always tells you what is not possible in nature.  Symmetric laws are sometimes called as ‘Prohibition Laws’.  These are some of the examples which I liked, but in book it covers many aspects of symmetry found in nature.  And lot more interesting examples. You will  really enjoy reading this book.

     “This Amazingly Symmetric World” is a book written by L. Tarasov and published by MIR Publication.  It is a general science book written in a very lucid language, and requires knowledge of elementary school physics to read.    Book begins with the conversation between author and reader (who is yet to know the world of symmetry) and finally ends with another conversation between them, but now reader has seen the beauty of symmetry.  Conversations are joy to read.  The book has two parts, ‘Symmetry Around Us’ which will show you symmetry found around the nature that we live.  And the second part is ‘Symmetry at the Heart of Everything’ which talks about the symmetry found in elementary particles and how our conservation laws are said to be universal laws.  I feel reading about symmetry is like reading nature’s beautiful power!  This book really shows  you that.   I am sure when you read this book, you will definitely say, beautiful and powerful tool of nature is symmetry!  Without this nothing would have existed!

     And also we always study many topics in science in a narrow field, and think why we need to study all these? What is so special about these things?  But when we come out of it and start looking at these beautiful things in a big picture, it wonders us, and gives more clarity about why we need to study these things, and what are the roles they play in nature.  This is true with symmetry or for that matter any topic in any subject.

e-copy of this book can be downloaded here…

(I would like to thank my teacher Mr Madusudhan sir [Scientific Officer at Bangalore Planetarium] who showed this book and inspired me to read this book.)

-Viswa Keerthy S (06/07/2013)

Maxwell and his ‘c’

     If you ever type “Maxwell Equations” in ‘Google Images’ you get many images, like the one mentioned below.

God Said Maxwell Equation

     Have you ever thought why it is been shown like this.  What is so important about these equations.  If you want to know, read this article

     If you ask me about these equations, I will say these are the greatest equations in the history of physics.  These equations may not look beautiful to a common man.  But truly, it looks beautiful for a physicist.  I am writing this article not to tell you the mathematics or the physics behind these equations.  But to tell you the beauty of nature, which is hidden in these equations!

    Let me first tell you this,

  • E= Electric Field
  • B= Magnetic Field
  •  ρ = Charge Density
  •  ɛ = Permittivity of free space (Property of medium)
  •  μ = Permeability of free space (Property of medium)
  • J = Current Density
  • Inverted triangle symbol is called ‘del’ It is just a differential operator

(read ɛ and μ as “epsilon not” and “mu not”)

That’s all about these equations.

     Before Maxwell, Electricity and Magnetism are two separate theories in physics.  They were independent of each other.  But this person called “Maxwell” unified these two theories as a single theory, called “Electromagnetic Theory”.  He said, a moving charge produces a magnetic field, and a change in magnetic field produces current in a wire!  True, this looks obvious to us now.  But during Maxwell time (year 1865) this is a remarkable achievement in the field of Physics.  Later it said that, this is the second Greatest Unification Theory in the History of Physics since “Newton’s Universal Law of Gravitation”.  Einstein once remarked on Maxwell theory that “Most profound, most truthful that physics has experienced since the time of Newton”.  Believe it or not all his work on “Electromagnetic Theory” stands on the above four equations!  If you exploit each equation, hidden natures beauty will unfolds to you.  If you ask me what these equations means, in a crude language I will say, disturbance of Electric and Magnetic fields travel in space (medium/vacuum) as Electromagnetic Waves obeying above equations.

     As I mentioned in the first paragraph, I want to show one such hidden beauty from these equations.  Before that let me introduce you to a “Wave Equations”.  It is just a mathematical equation which governs the propagation of wave in space.  And the equation is…

Wave Equation

     Here, Ѱ is a wave, V= Velocity of the wave.  Don’t worry about the differentiation; just see the form of equation.  We will come back to this equation later on.

     Now, What Maxwell did is, he took two of his last equation, that is…

Last Two Equation

     And his aim was to write down the final equation, which “looks like” wave equation, the one I showed you in the above paragraph.  He did some mathematical manipulation to his equation, and finally arrived what he wanted.  His final equation was this…

Final Equation

     One for Electric Field, another for Magnetic Field.

     Here, if you compare these two equations to the wave equations.  You can identify E and B are Electric and Magnetic Wave respectively.  But notice that, these two equations don’t have the v term in it.  Instead, it has some other terms.  If you equate these two terms, you get…

V square

V final

     So, you (he) finally got the velocity in which Electric and Magnetic Wave travel in space.  Alright, until now everything was fair enough.  But the beauty lies after this.  Let me tell you, we have…

V final

     I said, in the first paragraph that  ɛ and  μ are the properties of medium in which wave is travelling.  And it’s a constant number for a given medium.

For instance, if you consider medium as vacuum.


(Ignore the units)

If you substitute and calculate the velocity you get…


This happens to be precisely the velocity of “Light”!

     Before Maxwell people had did experiment and found velocity of light.


     But Maxwell did not even think of light, he took electricity and magnetic theory, combined these two theories to get “Electromagnetic Theory”.  And said the disturbance of electric and magnetic field will travel as “Electromagnetic Wave”.  And now he has calculated the velocity of “Electromagnetic Wave”, it turns out that it will travel at a velocity, precisely equal to the velocity of light.  This means, “Light is also an Electromagnetic Wave”!

     Up to Maxwell time, Mankind did not know, what constitute the light, which was the most abounded form of the energy right through human civilization.  Maxwell unfolded this greatest mystery of nature by saying “Light is a wave made up of electric and magnetic field and they are called as Electromagnetic Wave”.  Truly a remarkable achievement by Maxwell!

     It doesn’t stop here, there is another beautiful thing which is hidden in this formula.  Let me again tell you.  Now we can safely write, Velocity of light is…

C formula

     Again, as I said ɛ and μ are constant for a given medium, and they are the properties of medium itself.

     Isn’t it strikes you that just a properties of a medium tells you the velocity of light, which is the ultimate speed in our universe!  And, what is also interesting is, experiment involving measurement of  ɛ and μ has nothing to do with ‘c’.  But yet their combination gives rise to ‘c’!  Velocity of light is controlled by the properties of medium!  Amazing result.  The same kind of argument can be seen in connection with velocity of sound. That is, you can write velocity of sound in terms of bulk modulus (property of medium) of the medium in which sound is travelling.  But in light, the bulk modulus turned out to be ɛ and μ of the medium.  Nature works same everywhere, and Maxwell showed us the beauty of nature through his equations.  I don’t have many words to say about these things, but this is truly amazing!  Let me remind you, Maxwell did not studied light, he just wrote down his equations on Electric and Magnetic field.  But all these things are just hidden in his equations; he himself did not know about these things.  But his results showed everything, about the hidden quantities.  He himself was surprised!  I have just showed you one example.  You can find many of them, if you exploit the equations.  Truly they are beautiful equations of Nature.

     Now, I hope you got to know why people write Maxwell equations like the one which I showed you at the beginning.  Light is all about Maxwell’s equations.  I personally believe, existence of God is zero. But, if he is there, and if he controls the nature, then surely he must have said this!  Because that is how nature is working.  And this genius Maxwell unfolded the God’s secret to Mankind!

     450px-James_Clerk_Maxwell_statue_in_George_Street,_EdinburghJames Clerk Maxwell (13 June 1831- 05 Nov 1879) was a Scottish man, and one of the greatest physicist during 19th century.  Apart from his “Electromagnetic Theory” he also worked on “Maxwell-Boltzmann Distribution” which is statistical way of describing “Kinetic Theory of Gases”.

Right: Maxwell Statue at Edinburgh. (Image from wikipedia)

-Viswa Keerthy S (29-06-2013)