A SEARCH FOR TRUTH
We, the human beings, homo sapiens, the pinnacle of intelligence and wisdom. Nature has provided us with the mental capability to look and understand the nature itself. We want to know the truth. Truth about everything from every day life that involves things, people and relationship to the grandiose cosmos.
Our quest has led us to discover new things, new perspective and new technologies but in terms of understanding ourselves, we do not know how far we have come. The debate of nature of reality is still on. From religions to mathematics and science to sorcery, we are still trying to seek the real nature of our home — the universe.
But what is reality by definition? Is it just a mere illusion? A cosmic dance of the absolute truth and the Maya as the vedic literature suggest? Or Are we a result of some divine intervention as suggested by monotheistic religions. These argument doesn’t lead us to the self sufficient answer. Instead, there can be more questions like who is the creator then? Or what is the absolute truth? Where would all these divine beings originate from? Since I am not trying to open a religious debate, we must shift our focus to the other quests. The path taken by Plato, Aristotle, Galileo, Newton, Einstein, Feynman. The path of science and reasoning. Like religions, it is also a long quest going back to the ancient Egyptians or perhaps even back when there was no recorded history. While looking for a divine reason of existence, Egyptians became one of the first cosmologists. While trying to see the future, the ancient Aryan astrologers were venturing in the world of astronomy or when pythagoreans were obsessed with numbers, they were developing a tool, a new perspective to look into the nature, mathematics. The tools and fundamental base of science started with a quest of divine being, purpose of human life and after 3 or 4 millenia, here we are. We have found many answers to the questions our forefathers wondered but our answers have come with more complicated questions and our search of identity is still in motion. Fast forwarding thousands of years of quest, we should look where we are now. How do we see the universe? How has the modern picture of reality evolved? And because of my interest, I shall only focus on the quest from the perspective of physics.
IN SEARCH OF SIMPLE TRUTH
We physicists are obsessed with truth and not just the truth but simple truth. If you ask any physicists, why is Einstein’s energy mass relation equation so beautiful, you will get one short answer…it is simple and it works. For some reason (reasons that I am not sure of …perhaps historical reasons), we believe the truth is always simple and if it is simple, it is beautiful. But it is not always truth. What is very simple and what sometimes works most of the time, might have minute flaws and those flaws open up the whole new perspective of nature and reality.
Our obsession with simplicity comes from our experience. A house is a complicated structure but it is made up of bricks and stones. Those bricks and stones are made up of small dust particles and we can go on and on until we come into the realm of quarks, gluons and electrons. Same goes with our bodies, the mountains, stars, river, plants or any material form. Everything in the universe is made up of a set of particles. It is so simple and so far it is true. Since there are only a few set of fundamental particles, we can find out the laws with which they interact with each other giving rise to the perceivable universe. Starting from Rutherford’s discovery of electrons, we have discovered the Higgs boson that gives mass to all fundamental particles. The Standard Model of Particle Physics (just like the periodic table in Chemistry, we have our own periodic table but it consists of fundamental particles and some laws what govern the whole universe) was finally complete with the discovery of Higgs Boson. The ultimate search of truth was complete right? With few sets of particles, the truth, we have been searching of is found. Or is it so? Not quite so. Although our periodic table got complete, the laws that govern these particles were as if brought together from various places and put together. It was as if instead of getting near truth, we improvised it. The standard model has 4 fundamental forces. 2 sets of particles (bosons and fermions) and nasty equations that would blow up to infinity if they are not normalized (in simple words, levelled up by equally large numbers). It gave us a bunch of constant numbers in the equations which no one knows why they are there or if they are also fundamental or a result of something unknown beyond our knowledge. To make things worse, it completely got the information about neutrinos wrong. It predicted that neutrinos (one of the fermions in lepton family, that are produced as a result of nuclear reactions going on in sun or our nuclear plants) were massless and yet they happen to have mass. And to make things even worse, it doesn’t really talk about gravity. The model described other forces like electromagnetic force, weak force or strong force in the form of fields which excitations would give rise to its mediators called bosons. To understand, lets look at electro magnetic field. The electric field gives rise to electric force which propagates through space in the form of waves. Light is electromagnetic wave. And they travel in the form of photons which are bosons and also particles. So, when we see the trees, the photons from the sun (assuming it is day time) strike on the trees and those photons bounce off and come to our eyes. Our retina then conceives it sends signal into our brain and we see the trees. Their different colors depend upon the frequency or energy of the photons. A red color comes from a photon with low energy and a blue color comes from a photon with high energy. Similar things is applied to the weak and strong force. Experiments have discovered these mediators of forces. But when it comes to gravity, all hell gets loose. Our fine picture of reality that looked so simple stops here.
A NEW PICTURE OF CONFUSION AND VODOONESS
I call the new picture vodooness not out of sheer superstitions but out of the hints we have got so far. We shall begin with the development of quantum mechanics.
In the early 20th century, it seemed like the physics was saturated. It was before the development of quantum mechanics. Newton had discovered law of gravity which governed the heavenly bodies and interactions of things in the earth and beyond and they worked perfectly fine. Light was well known in terms of waves and the recent discovery of electricity had shown the power of science. But there were small problems arising in between the festive era. Of course the world was preparing for the first world war and tensions were building among the European super power. At the same time, small fractures in physics kept on growing slowly. Scientists began to suspect that something was not right with the current picture of nature.
The first flaw came from thermodynamics. After the recent discovery of electricity, there were all kind of experiments going with light. In Germany, Max Planck was working on a very bizarre problem that couldn’t be explained by contemporary framework of reality. The problem was this. When we heat of metal rod, it gets hot. After sometime, it gets red and if we heat further, it will become bright orange. The white light as we know are made up of different colors (VIBGYOR). However, after yellow, it would never get Blue or violet. No matter how much it is heated, the rod would only glow more brigher but in the yellow orange spectrum. But wave mechanics dictates that as the input energy grows, there is no limitation for the energy and frequency of emitted radiation. By theory, it would mean it is possible to get infinite energy from an ideal black body. So, the problem was double edged. If it doesn’t work, it would mean the contemporary knowledge of light was all wrong and if worked, it would just violate the conservation of energy/momentum, the most sacred of physics. So, to solve this, Max Plank unknownly came up with a solution. He considered light to be small packets of quanta or photons (as we know today). And Einstein proved it. His proof and explanation of photo electric effect got him the Noble prize. But the honeymoon of physics was over. The perfect picture of the world had turned into shatters. If light was not wave but particles and if energy comes in discrete quantity, that means things don’t move or flow continuously but jump from one step to another. It was like when an electron moved from point A to point B, it disappears in between the transition.
To make things worse, Heisenberg and Schrodinger came up with mathematical tools to describe this bizzard world in terms of waves (but of probability). So the tool that we use to understand atoms do not tell the exact information about them but rather give us various possibilities and what we measure is the collapsed version of these possibilities into one final form which we see as reality. This idea was so wild that Einstein, one of the founding father of quantum picture, outright rejected it. After all, it is as if there is no objective reality after all. When we are not looking at things, anything and everything is possible and our very action of looking/measuring would give us one of the various possible pictures. If you are not baffled by now (assuming you haven’t heard this before), then let us scale this picture into macroscopic version. Imagine I have a box of chocolate. Our common sense tells me that if I open the box, I will see chocolates inside it because somebody had already put chocolates in the box. In other words, the information about the chocolate inside the box is already there. In quantum world, however, it means that until I open the box, there is no way to know if it has chocolate or not. In fact, quantum mechanics says there will and will not be chocolate with certain degree of probability and only when I open the box, one of the probable picture of reality will take the material form. In other words, there is no pre defined information about chocolate.
In the atomic scale, it means the very existence of a quantum particle (electron say) is because of our measurement. If the fundamental particles are the result of our measurement, what does it mean to our existence? Does it mean our existence is the result of interaction with everything else? Perhaps yes, perhaps no. But we know for sure that after thousand years, our quest to find objective reality has put us into a very bizarre situation. So far, quantum mechanics has been a very successful tool to describe the elementary particles. It is used in our daily lives in the form of computer (transistors), medical science and investigate the elementary particles. However, we still debate what does the equations arising from quantum mechanics mean to reality? Or does it even describe the fundamental particles, the very building block of nature? I have come to settle that quantum mechanics gives us how everything interact with everything in a minute scale. It is a tool to measure these interactions and if we follow our nose, it says that these very measurements give rise to the picture of reality. It is as if the very picture of reality is somewhat a subjective thing.
Now we should turn into another problem in physics. Gravity. So after ranting about quantum mechanics, we should accept one fatal limitation of our current knowledge of QM. It is that we do not know how to incorporate gravity into this quantum world. We currently have two separate working tools to understand one universe. One is quantum mechanics which effectively probes into the minute scale and describe the fundamental building blocks of universe. Another is general relativity which probes into grand cosmic scale. General relativity says that gravity unlike other force is not quantized. In fact, by definition of standard model, it should not even be force. It is a resulting effect of warping of space and time. GR says that space can be stretched, twitched, shrinked just like a bed sheet and time is just another face of space. In other words, space and time are same. This is such a bizarre proclamation that when Einstien first proposed it, there were only a handful people to understand it. Now lets see what kind of grand picture general relativity gives.
It says the earth is travelling in a straight line. But how is it possible? Earth is revolving around the sun in an elliptical orbit. GR says that the sun’s mass has stretched and space in such a way that space is not flat around sun. Instead it is like a funnel with the sun in the center. In that geometry, a round path is a straight line. This is a very surprising picture of universe. We are used to imagining the flat space. Straight lines mean line that will never turn around and end back to its initial position. However, in a curved surface things are a bit weird. If the space were a hyperbola, the sum of 3 angles in a triangle would be less than 180 degrees. Or to make things simpler, if we sail straight on earth from north pole, we will end up back to north pole after one complete circle. So far GR has spectacularly passed all the predictions it made including the gravitational waves..the rippling of space when two massive bodies collide or when a massive star dies in supernova explosion. Now lets look at how space and time are same from the perspective of relativity.
When we say something is fundamental, it should exist on its own. Its properties should be independent of other casualties. So, we begin by proposing that time is fundamental. If we find a contradiction, then our proposition fails. So, special relativity says and it is a proven fact that the speed of light is a universal constant. If I were on a train travelling at 80 mph, my speed with respect to the buildings outside is 80 mph. If a guy on the train is moving at 1 mph, his speed relative to me is 1 mph and relative to the building, it is 81 mph. Or, someone from the building would measure that the guy’s speed is 81 mph. So, velocity or speed is a relative quantity. But it doesn’t apply for the speed of light. No matter where you are, how fast you travel, it will always have a speed of 300000000 m/s and there is no debate on it. So, the only way this can happen is if the time slows down in such a way that the speed of light remains constant. That means, if I travel at 80 miles per hour, compared to people on the ground, my time is travelling slower. In fact, an astronomer’s clock in ISS is ticking slower than ours. If you were to hop on a space ship and travel at 99 percent of the speed of light and come back after 2 days of your time, it would be thousands of years (I don’t want to go to math here) back in earth. So, it seems like time is not absolute after all. If two events happen in two different places, some will say it happened at same time and some would say it happened at different time. This slowing of time when you move, as gravity says is because of stretching and contracting of the space. Time as we feel is a property of space. In fact, special relativity might say that speed of light is fundamental instead of time. (just like going from north to south or x axis to y axis and so on).
So, we have two different pictures of reality. One from QM and another from GR. One says that anything is possible. There is no objective reality. Another says that space and time are one thing and it is our illusion that makes us think they are two. Our picture of reality has two forms and both are far from everyday experience. So, perhaps truth is not simple. But can we have two forms of truth. That should not be true, if we still use of common sense although our discoveries have suggested us to toss our common sense when it comes to understand the picture of reality. However, there are efforts going on to unify gravity with quantum mechanics. If all 3 forces can be explained by one mechanism, gravity cannot be an outlier. If there are two similar things, chances are they have same origin. You and your brother look alike. Or we and apes look much similar compared to cats and dogs because our common origin is same. So, if we were to believe this logical regression then gravity at some point must join other forces, or at least a group of independent scientists around the world would like to think. Two big efforts are string theory and quantum gravity. I will only talk briefly about quantum loop gravity and its implication (and save string theory for another day).
Quantum loop gravity theory suggests that perhaps Einstein is right on saying gravity is the geometric manifestation of space time. However, it might be that space is still discrete. Just like lights are made up of photons, space is discrete. They are made up of small nodes intertwined each other and each node is a unit in space and their smallest distance that separates them (although personally I do not know what the definition of distance means when there is no space), quantizes the space. But what it means is if these loops are the building blocks of space then they exist nowhere. In nowhere they exist and yet they give rise to the infinite universe. It is an elegant theory but it just means that perhaps reality is nothing. It is a big illusion. The grand universe that spreads to infinity is nothing but nothing, I mean literally nothing and we the part of this universe are the product of this literally nothing nothing. Quantum loop theorists think that this kind of condition might exist in the black holes. As the black holes collapses, all its mass collapses into a small finite space. But since space is discrete, this collapse cannot go further beyond this limit and the black hole will rebound or the space inside it will expand infinitely fast. But since the gravity of the black hole is so strong, it would mean that for an observer outside the black hole, this rebound looks like an extremely slow process. Basically it says that our whole universe might be what is inside a black hole that is dying or decaying. It also means that there can be multiple universe and we might be the one with right amount of ingredients to come up with life and the intelligence to ponder about our existence and reality.
So, finally we are here. In the search of reality, we were on a point where we thought we knew everything and then the new perspective has put us nowhere. The current best theories give a very weird picture of reality. It is as if our very existence is because of us. Time is no more fundamental. Space can stretch and twitch and particles that we are made up of float in the mystic world of probability. New theories suggest that perhaps the ultimate reality is nothing bu a literal nothing. Does that mean, we give up hope? Does that mean reality in the end is nothing? No, I think the quest to reality is that mountain top where we want to be. It might be still far but on our way we have learnt a lot. We got a lot from those travelers who carried on the voyage to get to that mountain top and we are bound to contribute to our future generations. We might get nowhere in the end or this voyage will surely give us new ideas, new perspectives and new ways to look ourselves, our universe and appreciate our very existence. On our way to know more, we will discover new things to make this world a better place for future generations to come.