Can you imagine space as a curved and twisted fabric? Have you ever heard about vibrations in time? What’s so strange about Quantum world? How do we get a sense of existence if we are just a junk of lifeless atoms? Carlo Rovelli, an Italian physicist gives us a short introduction on these post Newtonian scientific thoughts and discoveries in his book Seven Brief Lessons on PhysicsIt is very small book, but full of scientific knowledge on some of the magnificent discoveries in physics, beginning from twentieth century.


 

(1) General Theory of Relativity: Physicist Lev Landau calls this the most beautiful of theories. Of course, it is. Special Relativity challenges the Newton’s theory of gravity and elucidates the idea of space as the gravitational field itself. You may think that space is distinct from matter. But in reality it behaves as a material component of the world which undulates, flexes, curves and twists. It can expand or contract. Doesn’t this seem absurd? It may, but this is real. Einstein demonstrated a perfect solution for the cause of gravitation through this concept of curvature in space. Not only space, even time also curves along with it. He predicted that time passes more quickly high up than below, nearer to Earth. This time dilation in space-time continuum was reportedly proven by Hafele-Keating experiment later on.

(2) Quantum Mechanics: Another theory in modern physics which changed our perception about nature. Max Planck and Einstein, both individually came to a conclusion that energy seems to be made up of finite packets called ‘quanta’, which was peculiar to our earlier understanding of energy as a continuous wave. Niels Bohr also theorised that electron energy takes up only certain values like photons. These marked the beginnings of Quantum mechanics in 1925, replacing Newtonian classical mechanics. The strange behaviour of quantum world like wave-particle duality, uncertainty in finding electron still puzzling our understanding of objective reality.

(3) Architecture of the Universe: Our visualisation of the Cosmos has been changed among the ages, from flat Earth to the Big Bang and from Aristotle to Stephen Hawking. Through the advanced technology of our telescopes now, we gained a better picture of planets, distant stars, galaxies and nebulae. For instance, take a look at this image captured by Hubble space telescope in 2004.

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This is the deepest image of the Universe ever taken by us. It is a picture of a small region of space in the constellation Fornax, containing an estimated 10,000 galaxies. You are looking back approximately 13 billion years (400-800 million years after the Big Bang) in this image.

Now imagine, in the midst of this vast Universe, how infinitesimally small we are !

(4) Elementary Particles: Matter is made of atoms, which consists of protons, neutrons and electrons. Both protons and neutrons are made of even smaller particles called quarks. Every material reality around us is built by these elementary particles (electrons, quarks, bosons, photons and gravitons). But these particles do not have any sort of physical reality, they exist as the quanta of corresponding fields. They disappear, reappear and continuously swarm according to the laws of quantum mechanics. Scientists are trying to predict the behaviour of these particles with the standard model of particle physics, yet it falls short of being a complete theory due to exclusion of gravitational field. Recent evidences prove that 80% of the Universe comprises dark matter which exerts gravitational pull in the Cosmos. What it comprises of? we don’t know.

(5) Quantum Gravity: This new theory attempts to merge the two extraordinary theories discussed above, General relativity and Quantum mechanics, proposing that space could also be made of quanta. It says, space is made of extremely minute grains or loops, linked to each other weaving a texture. Just as the idea of continuous space disappears, so the idea of elementary ‘time’ also vanishes. If this theory is correct, matter cannot really collapse to an infinitesimal point as only finite chunks of space could exist in the end. Does this suggest that the starting point of Big Bang might be a past Universe contracted under its own gravity to a tiny space?

(6) Time:  Extension of Thermodynamics to gravitational field is still problematic. How gravitational field behaves when it heats up? Can there be any thermal vibrations in space-time, since gravity is itself space? What is a vibrating time? What exactly is the flow of time? Physicists conclude that universal flow of time is just an illusion and our experience of passage of time does not need to reflect the fundamental aspect of reality. The ‘present’ may not be an objective sense, but the microscopic interactions within the world prompt the emergence of temporal phenomena within a system (say, ourselves) which only interacts through the medium of a myriad of variables. Our memory and consciousness are built on these statistical phenomena. Now think about this. For a hypothetical super sensible being, time would not seem to flow at all: the entire Universe would be a block of past, present and future.

(7) Ourselves: So far, we have seen the swarm of ephemeral quanta of space, matter and elementary particles. In reality, we are also made of same atoms. Does this mean that we are just mere quanta and particles? Then where do we get this sense of individual existence and consciousness? We still don’t have a convincing answer to this question. But attempts are being made to characterise quantitatively the structure that a system must have in order to be conscious.

Can we find clue for consciousness through science in coming days? We may or may not. But our quest for knowledge will never cease. Through these years, we slowly uncovered the true nature of space, time and matter, which were mind blowing discoveries to grasp at first.

But who knows, there can be even more strange things in physics we are yet to discover.


 

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