Man has always been curious and been investigating the nature of things. He has probed into the ‘why’ and ‘how’ of all phenomena observed. As science evolved, he came up with laws and equations to represent these observations. For many decades, if not centuries, he was satisfied with explaining everything around him using what is today known as ‘Classical Mechanics’. All bodies and phenomena observed could be explained by Newton’s Laws and his equations of motion. In fact this developed into the branch of Classical Mechanics and saw a huge leap in the field of Science. Be it describing space, or fluids, or cars, or day to-day experiences, classical physics had all the answers. Then suddenly, with the extensive research in finding the atomic model, scientists slowly discovered that at the microscopic level, classical physics that had worked beautifully so far seemed to fail. This led to the conception of Quantum Mechanics – a new set of rules that were said to govern the Universe.
It is both interesting and perplexing that nature should work differently at different levels. After all, we are all made up of atoms, and it looks like, as a whole we follow classical physics, but when we get down to a constituent atom, ‘classical thinking’ does not help. The debate on the atomic models, and the discovery of the electron, consequently led to the branch of Quantum Mechanics, which has altered our lives in ways unimaginable. Quantum Mechanics saw the development of Electronics, the importance of which needs no stating. Quantum Mechanics is also the reason for rapid growth in technology that we have experienced in the past few decades. Quantum concepts are very abstract, but ironically describe mathematically the behavior of systems quite accurately. These concepts have always gone over my head – from their conception, to further developments, exactly what happens at the quantum level is very difficult to comprehend, especially for someone who is very used to looking at things the classical way.
I was introduced to the concept of Quantum Mechanics years back, in my Physics class. Initially it sounded all big, but still very achievable. In fact, out of interest, I began reading advanced books on Quantum mechanics – probably the biggest mistake I made. It not only did not help me understand it better, it also gave me an illusion of having understood it. Next class, when my teacher told us in class, “Do not get bogged down by the enormity of Quantum Mechanics. I don’t expect you to understand it now, or even a year later. In fact if you say you understand Quantum mechanics, I would say something is wrong with you.” And I thought that is an exaggeration. But today, after having delved into the subject, after extensive research, I understand that I know nothing about it. It is just too hard to visualize – Quantum mechanics is a quantum leap from the conceivable to that which needs powerful imagination.
Before talking about the research aspects, I want to emphasize the importance of the subject. In specific, I would like to deal with how levels or sizes have altered perspectives, and yet related them, in two branches of Science - Astrophysics, and Electronics. These are chosen because the former deals with bodies the size of the Earth or more, while the latter deals with microscopic (and nanoscopic) particles. How things work at different levels has been significant in my pursuit to understand Quantum Mechanics. According to me, man’s search for the truth and quest to find answers can be done two ways: either start from the Universe and come down to the smallest particle, or the other way round.
As far as the Universe is concerned, more than laws or mathematical expressions, models and theories work better. In order to answer the question of the origin of the Universe, the two most popular theories are the Steady State Theory, and the Big Bang Theory:
Steady State Theory: This stated that the Universe is more or less a constant at every point in time. According to this theory, new matter is created when galaxies and celestial bodies move away from one another. This concept was pioneered by the English astronomer Sir Fred Hoyle. Though this theory was well supported by the scientific community for a long period, the later experimental results and evidence pointed towards the Big Bang theory being more plausible.
The Big Bang Theory: This model is the foundation for all research in the field of Cosmology today. According to this model, the Universe was initially in a hot dense state. From that point, the Universe has been expanding continuously, and evolving with time. The cosmic microwave background supported this model strongly, which gave it the upper hand against the steady state theory (“WMAP’s Introduction”, 2013). Since then, there have been numerous results from scientific experiments which support the validity of this theory. A picture of the cosmic microwave background (Figure 1) and its spectral response (Figure 2) are shown below.
Figure 1: Cosmic Microwave Background
Figure 2: Spectral response of the Cosmic Microwave Background
The electron was discovered in the late nineteenth century. Various models beginning from Thomson’s model and Rutherford’s model were used to describe the atom and how its constituent particles behaved. When Neil Bohr came up with his model and postulates, it was faced with criticism and dismissed as it was against the then existing concepts of Classical mechanics. However, soon scientists began to see how Bohr’s postulates seemed to work at the microscopic level. This was the break through that led to the concepts of Quantum mechanics.
The idea that fascinates me most in the background study to understand Quantum mechanics is how it is related to so many other branches of study, and how all fields integrate beautifully in the end. I realized that before attempting to read on quantum concepts, it is important to read all related topics. For example, electro magnetism and theories, wave optics, chemical bonding and nature of particles, energy and thermodynamics are important considerations. I would like to talk about entropy in particular, that helped me comprehend energy and how it is related to matter all around us. I watched many videos and read books, to gain at least a partial understanding. I have described this below:
The concept of energy as known today was conceived way as early as in the 17th century. Initially, it was only an abstract phenomenon which scientists found it hard to quantify for many decades. Energy was then more of a philosophical entity than a scientific one. Through observations and relentless studies, it was years before Science could associate a more refined explanation of energy. From breathing air, to digesting food, our body is perhaps the best example of a machine that harnesses energy. It is possible that scientists such as Gottfried Leibniz took cue from this – he imagined the Universe as an enormous machine that obeys certain laws. From his time, until the present, the concept of energy has evolved. From survival to luxuries, it is impossible to imagine life without energy today. Thanks to the field of thermodynamics, humans are getting closer to unravelling the mystery that energy is.
The idea that there is an immense ‘potential’ inherent in the Universe, and that if harnessed, it could give mankind unimaginable power was first given by Gottfried Leibniz. He imagined the Universe as a living machine with a definite amount of ‘energy’. Such an idea struck him while observing the nature of a collision of two balls, in which the motion of one changed the other. In essence, he said that there was some kind of physical quantity being exchanged. He also realized that a massive amount of this physical quantity is released from gunpowder, fire and steam. The idea that this ‘energy’ could be harnessed for other useful purposes struck him then. Leibniz soon communicated his idea to the French scientist Denis Papin – the two of them realized that heat released from certain events could indeed be harnesses. And Papin was in doubt that it would provide man with infinite power. Though they could not proceed with any useful practical models, their theories laid the foundation for future scientists ("The Story Of Energy").
The branch of Science known as ‘Thermodynamics’, probably started with the work of Nicolas Leonard Sadi Carnot, a French scientist. He wanted to understand the core of the steam engine – the power of Britain, in order to better the model for his own nation. Upon studying the steam engines that existed then, he realized that ‘heat’ energy behaved much like that of water at a height. Just as water flows from a higher potential to a lower potential, heat flows from a hotter body to a colder body. As he observed this, he realized that all that one had to do to harness more energy was to increase the difference in temperatures of the two bodies in contact, much like increasing the height of water to increase potential energy. This simple understanding would increase the efficiency of heat engines dramatically. Though unfortunately he did not live to see the impact his work had on the world, it is evident in every vehicle today – from cars to jets. His work will no doubt continue to be used for years to come ("The Story Of Energy").
As I mentioned earlier, there was a sudden leap in the field of Science towards the end of the 19th century. With fields branching out and many scientists working on different experiments, more data was available for analysis. It was during this time that scientists started looking at matter at a microscopic level, in which the Classical or Newtonian mechanics seemed to fail. Notable people who came up with the theory of atoms and proposed atomic models are J.J. Thomson, Ernest Rutherford, and Neil Bohr. Bohr’s theories indeed paved the way for Quantum mechanics as known today .The beginning of all this was however, Boltzmann’s theories. Boltzmann could clearly explain what was happening at a microscopic level, when there was transfer of energy - according to him, matter was made of smaller particles which were continuously moving, and it was this motion that caused a flow of energy. For example, the molecules of a hot body were moving fast, and transferred their energy to any other molecules they came in contact with. He also explained what entropy means and why it should be ever increasing (Tait, 2007).
The equation dsdt≥0 was already given, to show that ‘entropy’ of the Universe is continuously increasing. However, the term entropy was not very well defined and scientists had difficulty comprehending the quantity. With Boltzmann’s proposals, the problem seem to be solved, though they were not accepted in his time. That left to itself, any system with order disintegrates to spread disorder is the essence of his theory. In other words, change is inevitable. It was shown that matter necessarily interferes with surroundings to create disorder. For example, a mug of hot tea left on a table would gradually lose heat to the surroundings and heat it. Thus, the order in the mug of tea creates disorder in the surroundings. This measure of order (or disorder) can be associated with entropy. And considering the Universe as a system left on its own, it too must eventually disintegrate from the chaos and disorder building up. What man has managed to do is merely utilize the energy released during the transition from a state of order to disorder –he has constructively used this energy to create the world of buildings, machines, and high end technology. In fact, scientists working in the field of thermodynamics are now trying to imitate the fusion process going on in the Sun, in order to harness infinite energy ("The Story Of Energy").
As can be seen from the above explanation, Thermodynamics is closely related to Quantum mechanics. I began to realize that all branches of Science, in some way or the other are trying to find out the same answers. From the different perspectives of each branch, the concepts all finally head to the same place – the question of the origin of the Universe; of how and why nature, from a sub-atomic particle to celestial bodies, behaves in a certain way. I may not have succeeded in understanding the Schrodinger’s equation as it ought to be; I may not have understood the complicated atomic spectra or the quantum nature of the electron, but I have succeeded in integrating various branches of study, that I believe will ultimately lead me to unravel the mystery of Quantum mechanics. Some important things I’ve learnt are, to appreciate the history of Science, and to relate concepts and not study them from an isolated perspective.
As a normal human being with a curious mind, the questions that have troubled science and religion alike have bothered me too. I have not only attempted to unify various branches of Science to aid my understanding of nature, but have also tried to analyze the point where science and spirituality/religion have the potential to meet. It is difficult trying to imagine concepts beyond the boundaries of reality that can be sensed. Grasping abstract concepts requires a great deal of perseverance and imagination. Many years back, I decided to do whatever it takes to get there – the journey of exploring ideas on my own has been incredibly exciting – I hope this passion and process of learning continues for a long time to come.
WMAP’s Introduction to Cosmology. (2013). Retrieved July 10, 2013, from http://map.gsfc.nasa.gov/universe/
"The Story Of Energy." Perf. Jim Al-Khalili, and Prod. Paul Sen. Order and Disorder. BBC Four: 16 Oct 2012. Television.
Tait, P. G. (2007) “Sketch of Thermodynamics”, University of California: Edmunston and Douglas