Tag Archives: physics

Some fun and interesting facts about friction

As the basic definition goes, friction opposed relative sliding between two surfaces in contact. A common misconception is that friction opposes motion. Following are some fun facts about friction. I’ll also include the findings of my discovery in the field of friction.

  • Almost all the work you do in daily life relies on friction. Friction is an electromagnetic force. It’s basically the nuclei of one surface pulling the electrons on the other surface and vice versa effecting in the two surfaces holding each other. So, whenever you pull or hold something, you are able to do it because of friction.

  • Many people wonder how our universe would have been if friction was not there. Well, our universe wouldn’t have existed if friction had not been present. Yes, that is correct. As I said, friction is an electromagnetic force acting between atoms of two surfaces. That means, wherever there are atoms, there is electromagnetic force and thus, there is friction. So, it can be said that friction is an unavoidable outcome of the existence of atoms. Atoms form molecules which are held together by electromagnetic force or friction which help in forming matter. Microbes, animals, us, the earth, the other planets, the stars, none of them would exist without matter and therefore friction. All that the universe would have had is floating electrons and nuclei of elements.

  • Friction is the reason why we can move. When we walk, what is happening between our feet and the ground? Effectively, we are trying to slide the feet backwards and the friction pushes us forward. It is almost the same for cars and motorcycles or anything that moves on wheels. Yes, it is undisputed that sliding forward on a frictionless surface or while being levitated is most energy efficient but we are not able to do that yet on a daily basis.

  • Life exists because of friction. It is needless to say that without friction there won’t be any matter and life can’t even find a basis to start on. Let’s say there was accidentally a surface formed in this universe, containing only nuclei and electrons just moving in contact with each other due to a common momentum (momentum is the product of mass and velocity of a body). Still, there is no chance of formation of the type of life known to us on this surface without friction. The reason is life needs binding of atoms and then matter flowing over other matter which can only happen if friction is present. Otherwise, binding of atoms based only on perfect combination of arbitrary momenta is highly improbable.

  • Now, I’ll give some information about my discovery related to friction between sliding surfaces or in one word tribology. Me under the guidance of my professor Dr. S K Roychowdhury, a man I place in high regard discovered that X-rays are emitted when a surface slides on another surface. This work was further carried on by G. N. Krishna. The details can be found in: X-Ray Emission during Rubbing of Metals, Vol. 36, No. 3 (2014) 229-235, Tribology in Industry, Tribology in Industry

That is all I have to say on this subject till now.


Thermal Equilibrium with some humour

The other day, I was asked by a student to explain thermal equilibrium. I told her to guess an answer. So she said that thermal equilibrium between two bodies means they are at equal temperature and there is no flow of heat between the two.
I said, “you got the first part correct and second part wrong. There is equal heat exchange between the two bodies”
I added, “the electrons carry heat and the amount kind of depends on the body’s temperature.”
She asked, “if the other body is at the same temperature then why would the electron carry heat there?”
I answered, ” it is because electrons don’t have phones.”

7 compelling pieces of evidence of the existence of parallel universes

This might seem an excerpt from science fiction but it is not. Scientists have been working to find the existence of parallel universes since decades with no solid proof. However, we have come across certain pieces of evidence which suggest parallel universes may exist.

1. The Many Worlds Theory: It is a hypothesis produced by the physicist Hugh Everett in 1957 suggesting all possible alternate histories and futures are real within their own worlds. It could be a lot more complicated than that, but the version that most will understand is that there are a large – possibly infinite – number of universes, and everything that could possibly have happened in our past occurred in some other reality.
2. Weird Artefacts: There are actually a significant number of artefacts, found through archaeological digs or otherwise, that nobody can explain the origins of. The sort of dusty leftovers from old civilisations that usually crop up at such occasions, except experts can’t pin point where they actually came from. Carbon dating doesn’t work, they’re unfamiliar to any particular period of history.


This photo is of the infamous Antikythera mechanism, a sort of stone computer found near a Greek island that nobody can explain. So what’s with all these weird things? Are they simply artefacts from eras and civilisations that were never recorded, and thus fell down the cracks of the annals of history? Are they some sort of leftover from time travellers? Are they forgeries? Or could they be some sort of object from an alternate reality that somehow slipped through into ours?
3. The Story Of Lerina García: Lerina wasn’t an alien. For Ms Garcia, the truth was far more terrifying: the reason, that her morning routine seemed so completely off, that she didn’t recognise her co-workers or the things that cluttered her home, was because she’d slipped into an alternate dimension. All the small incongruities added up to make not other explanation seem possible. That’s if it isn’t a hoax, and she didn’t just suffer from memory loss. However, I should mention she did get herself checked by a doctor and there was no trace of drugs or any other medicine.
4. Deja Vu: Ok, this can easily be a hallucination but we can’t say for sure. It’s one of the most singularly peculiar experiences you can have as a human being, and yet, it’s happened to nearly everyone: the uncanny sensation of deja vu, where you enter a situation or do an action or see something, and get the feeling that it’s happened before. Usually it’s put down to some misfiring of the brain, perhaps retrofitting the memory to think that something’s more familiar than it really is (for whatever reason). Even more strange is deja vecu, which is the feeling that you know what’s going to happen next, too. There is something else, known as alter vu where one remembers their history differently.
5. The Man From Taured: This happened when humanity was visited by a caucasian man from Taured. In 1954 a man arrived into Tokyo airport with a passport from a country that didn’t exist. Customs officials detained the man, on the charge of carrying fake papers to try and get into Japan, but he was adamant: Taured was a real place, a European country with thousands of years of history, and that he held other papers (bank statements and the like) with the name on. The place he showed as Taured was actually Andorra according to our maps. After several hours of interrogation, they put him up in a hotel, and the next morning he vanished along with his papers in the Japanese authority’s locker.
6. Dimensions In Time: Our understanding of the universe exists across a 3D vector. In actuality there’s a fourth dimension, and humans are only capable of viewing static slices of that 4D system. Beyond that there might also be the fifth dimension, which is really the preserve of mathematicians and physicists, but it’s known to exist: that’s basically a parallel world, as shown in the movie Interstellar.
7. The Double Slit Experiment: According to quantum mechanics, which describes the motions and interactions of particles at a fundamental sub-atomic level, we have a good idea of how the universe works by observing the behaviours of electrons and photons. Which, apparently, can be in multiple places or multiple states of existence simultaneously. This is called superposition. That’s kind of like the idea of alternate realities.
It’s a pretty simple test, provided you have the right materials. All you do is shoot a individual electrons through a sheet of a material with two vertical slits in it, and onto a blank white screen. There is a 50/50 chance the electron will go through each slit. You’ll also get to see the electronic interacting, interfering each others…except only one is around at the time. How is this possible? It’s because the electron might be existing in multiple places at the same time. Take that to a wider view, and you’ve got the many world theory in action.

A short story of discovery of dual nature of light

I had read about how it was established firmly that light had particle nature in high school. When I started teaching different theories about light I started wondering why was photoelectric effect needed to establish that light had particle nature? Light forms shadows on opaque objects. Only particle beams of radiation can form shadows as far as I knew. Why was formation of shadows not a more basic proof for light’s particle nature? So, I asked this question on Quora and quite a few learned gentlemen helped me out.

Before the photoelectric effect was understood, the only instrument scientists had to examine shadows was the human visual system.  Many of the later optical sensors were based on the photoelectric effect.  We can do better today with semiconductors in LCDs, but that came much later.

The problem with making deductions from what we see is not in one-to-one correspondence with the light patterns entering the eye!  Anything deduced from the appearance of shadows would have to be taken as at least a little suspicious.  Even our optical sensors are not perfect, but they are much better than the human eye if we want to get quantitative reproducible results. Researchers have shown that the sharp boundaries we see in clear shadows aren’t there!  They are artifacts of the processing by our visual system.

Actually, shadows have been extensively investigated and their complicated nature was part of the original proof for the wave theory of light, over and against the particle theory of light.

The particle theory became widely accepted because Isaac Newton was an exponent of it, despite many observations he himself made which indicated there might well be wavelike properties to light (eg Newton’s rings). He was so highly respected and did such critically important work in Optics that many people believed him when he said that light was made of particles.

But Christiaan Huygens at the same time advocated a wave theory of light. This led to a long controversy. It was hard to decide the controversy for sure experimentally, because the wavelengths of light are very small, and it required building small structures and using very bright light sources to be certain in the experiments, and the only very bright light sources in early times were not monochromatic sources but had many wavelengths in them.

Thomas Young did a very famous and brilliant experiment with two slits, that clearly showed a wavelike behaviour for the light on the other side of the slits, by demonstrating an interference pattern in the shadow, many people refused to believe his result which showed that light was a wave. Young became frustrated and went into other pursuits, including Egyptology, where he contributed to the early deciphering of the hieroglyphs. His contributions also lie in solid mechanics eg the change in length of longitudinal structures upon heavy load.

A question that came up was what should be the pattern of the light that passed through a circular aperture in an opaque wall. In other words what should the shadow look like?

A competition was held by the French Academy to calculate this. Fresnel did the calculation brilliantly using the wave theory of Huygens and came up with a particular diffraction pattern.

Poisson, a very strong advocate of the particle theory, decided to calculate instead what the shadow of an opaque circular disc should be using Fresnel’s method. He found that there should be a bright spot right in the middle of the shadow. He declared that this showed that the wave theory was complete nonsense: he thought the bright spot couldn’t possibly make any sense.

However an experimentalist by the name of Arago went and measured the shadow very carefully. He found the bright spot right in the middle of the shadow just as the wave theory demanded!

So real shadows were quite hard to explain with a particle theory of light.

Newton had in fact done a similar experiment to Arago, but the dimensions of Newton’s apparatus were such that he could not have seen the effect.

This established the wave theory as correct in almost everybody’s mind, and that belief was cemented further by the discovery of the laws of electromagnetism and the formulation of Maxwell’s equations, which gave a basis for understanding light as an electromagnetic wave.

An explosion of experiments was done in the late 19th century on electromagnetic phenomena of all sorts to test the Maxwell equations as far as they possibly could be tested.

But there was still some controversy – cathode rays were discovered and it was uncertain what their nature was. After all, the atomic theory was also around and it was very successful in chemistry. There were clearly particle like aspects to matter, so why not also to light?

Heinrich Hertz was the first to show that electromagnetic waves really propagated with the speed required by Maxwell’s equations, the speed of light that is. By about 1890 he had also discovered the photoelectric effect. But what he discovered at that point in time was still quite primitive – he observed that if he shone ultraviolet light on the electrodes in a spark gap, it produced sparks much more easily.

In 1897 J J Thomson showed that the cathode rays could be interpreted as if they were a particle, called the electron with a fixed charge to mass ratio. This was critical, because now, when you thought of shining light on the metal electrode in the photoelectric effect, you could imagine that electrons were being knocked out of the metal cathode.

But everyone still thought that light was a wave. The wave theory had been tremendously successful.

It took some time before the photoelectric effect could be investigated quantitatively, using different metals with different applied voltages, and critically, using different and also very low intensities of light. These were not easy experiments to do at the time.

The wave theory and the Maxwell equations, which almost everyone by that time believed gave the correct description of light, made a definite prediction for what would happen as the intensity of the light was reduced in the photoelectric effect. This was that eventually, as the intensity of the light was reduced, it would take a very long time for any electrons to be emitted from the metal.

But when the experiments got to be good enough, that was not what was observed – what was observed instead was that the photocurrent appeared immediately, whenever it did appear at all, and no matter how dim the light source was. There was no time delay after turning on the light. Also, the photocurrent did not appear at all when the frequency of the light was less than a certain value, a value that depended on the metal. What this clearly was showing was that something was very wrong with the Maxwell theory.

So when Einstein explained this effect in 1905, by saying that light was composed of “light quanta” with fixed amounts of energy depending upon the frequency of the light, along similar lines to the solution Planck had given to the spectrum of the black body radiation, the study of the photoelectric effect was still pretty new – it was only 15 years since the effect had been discovered by Hertz.

But this observation and the explanation were both essential to justify thinking of light as a particle.

So, I understood this gave a very strong evidence that light came in small packets or quanta with fixed amounts of energy: if bright light were made of waves of very large amplitude and dim light were made of waves with very small amplitude, then the energy that dim light would transfer to an electron would take some time to build up, before it would be enough to kick an electron out of the metal. But it the light was made of little packets and transferred all of the energy in a packet at once, then the electron could be kicked out as soon as one of the first packets in the light hit the electron in the metal, which would be very close to the point in time when the light was turned on.

The Maxwell theory could not account for this as it stood.

It was the detailed experiments that mattered – they took a little while to do, but not so very long after the effect was discovered.

The experiments had to be done in a pretty good vacuum, or else nothing could be seen at all, and that is also why it took until the late 19th century to do the experiments on the photoelectric effect. Vacuum was need because otherwise the ejected electron would have collided with atoms in air and thus no current.

That is also why no one discovered the electron until JJ Thomson, in 1897. He could prove that the cathode rays were particles, because he was capable of making vacuum tubes with a very high vacuum in them. The presence of even a little bit too much air in the tube changed everything you saw in the experiment to the point that you couldn’t be sure if the cathode rays were really particles or were really waves.

Now not everyone accepted that light had a particle like nature yet, even after Einstein’s explanation. This took some time – the final deciding factor was the observation of the Compton effect. In the Compton effect the result of the scattering of a single photon on a single electron could be seen, and the Planck-Einstein relations for the momentum and energy of the photon were verified.

After that, nobody could really doubt very strongly that photons existed.

The Universe and its beauty

Today, I won’t be talking about any social issue. Today, I would be talking on an issue that I feel connected to, the Universe.

I’ll be condescending for next few lines. Whatever I am going to say won’t be legible to most of the human population. The reason is they never tried to observe or feel. A person should know that a human life doesn’t hold much importance when compared to the events taking place in this universe. However, it does not mean a human can not contribute to this wonderful creation.

I have always been fascinated whenever I thought about the celestial bodies. They are huge and yet they move with great speed. The stars even though devastating at close range fuel life in planets. For instance our Sun, there would not have been any life on earth if the Sun was not so hot. Since, past few months I have been led to believe that our Universe is not the only one. There is no logical explanation otherwise. I mean, it is too strange if some universe came out of the blue and happens to house life in it. Quite a few physicists believe that there is an ocean of energy out of which Universes are formed like bubbles. The ones which are stable grow larger like our universe. The reason to believe this theory is why should our universe be the only one? There are so many planets, starts and galaxies in the universe then why should it be the only one? Most people won’t want to believe it because it would include an encounter with infinity. Infinity is a bit scary because it is unknown. I am not afraid of it because I have learnt to not fear the unknown. There is no rational reason to fear the unknown.

Now, the other universes may not be governed by the laws governing our Universe. For example, the universal law of gravitation follows inverse square law. The other universes may be governed by some other law. It maybe inverse cube law or simply inverse law. As far as I can perceive, our universe was the result of an experiment, a successful one. Maybe, there is some guy who conducted the experiment whom I consider as God. Maybe, he improvised on his work and created another universe which we don’t know about.

Frankly, I have absolutely no idea how another better universe would be like. Maybe, there will be less humans. I look at my universe and it is magical. Everything is in place. Anyone who has read high school physics would know there are four fundamental  forces in nature which are:

1. Gravitational Force: The weakest force that makes the planets go around a start or a star go around the centre of a galaxy. The effect of this force can be felt over almost infinitely large distances.

2. Electromagnetic Force: It is a much stronger force than gravity and is effective between two charged bodies. It’s range of effect is also almost infinite and follows inverse square relation like gravitational force. Most of the phenomena in our daily life are governed by this force.

3. Weak Nuclear Force: This force is also known weak interactions and is responsible for phenomena like beta decay in heavy nuclei. Its observable effect has a very short range, around 0.1 fermi. However, its behaviour is similar to electromagnetic interactions at larger distances.

4. Strong Nuclear Force: These are the strongest forces that can be observed in nature and are limited to 1 fermi which is almost the size of a nucleus. These forces are responsible for keeping the nucleons together in the nucleus. These forces are practically unobservable beyond a distance of 10 fermi.

Now, let me explain the beauty of their combination. They have a certain range and maintain a certain balance in the universe. What would have happened if their range changed by a little bit. What if the range of strong nuclear forces was equivalent to that of gravitation? Our universe as we know of it would not have existed. It would have been just a blob of matter. Similarly, if the gravitational force had a smaller range then our Universe would not even have a blob. Almost every heavenly body would have moved apart from one another.

Do you now see how delicately balanced our universe is? It is as if someone meticulously designed everything and put it in one place and thus the universe came into being. There is absolutely no option for error and the one doing this did it perfectly without any error. There is another possibility that our Universe is an improvement upon another universe. I don’t know what a perfect universe might be because I am not intelligent enough. However, I can not stop marvelling at the beauty of my Universe and would do anything to explore each and every corner of this masterpiece.