The Greatest Speech Ever Made

An inspirational speech by comedian Charlie Chaplin from the film "The Great Dictator", 1940.

3. Quantum Mechanics

The birth of our universe, namely the Big Bang, is described by scientists as a 'quantum event'. What does that mean?

All natural phenomena are governed by the laws of quantum mechanics. However, much of our day-to-day activity and experience can be well-explained in terms of the laws of classical mechanics, propounded, among others, by Newton. Classical mechanics is a good approximation (but only an approximation) of quantum mechanics under certain conditions. Newton's three laws of motion are examples of laws of classical mechanics. When does the approximation become invalid, and it becomes necessary to invoke laws of quantum mechanics directly for explaining a natural phenomenon? One situation is when the spatial dimensions are extremely small. A tennis ball is so big that classical mechanics is adequate for describing its trajectory. An electron is so small that only quantum mechanics can explain its behaviour properly.

Is an electron a particle or a wave? Experimental evidence says that it is both. An electron has a certain mass and electric charge. If we apply an electric field, we can accelerate the motion of the electron, which we can correctly calculate by assuming that it is a particle having the known mass and charge. So it is a particle.
 
But now consider the famous double-slit experiment first performed by Davisson and Germer in 1927. They shot a beam of electrons through two parallel slits, and recorded the positions of the electrons on a flat screen on the other side. What they found was that the electrons behaved, not as particles moving in straight lines, but as waves, forming a diffraction pattern like the one you would expect from a beam of light. So electrons are waves also. This experiment established the wave-particle duality of elementary particles like electrons.

 

There are serious consequences of this conclusion. A particle can be assigned a certain position or 'coordinates' in space. But we cannot do that for a wave. Consider the familiar sound waves in air. As a sound wave travels, there is compression and rarefaction in air. Some of this vibration of air reaches your ears, and you sense the sound. But can you tell that the sound wave is here and not there? No. It is everywhere; with different intensities, of course.
 
So, if an electron has wave properties, it means that it is everywhere at the same time! We say that it is delocalized. This is one of the shocks that quantum theory inflicts on us. There are many more. And yet, it is the most successful and the most thoroughly tested theory, or model of reality, ever.
 
The wave nature of electrons is a reality. Otherwise we would not have been able to build the very important and much used electron microscopes. In these devices, electrons do what is done by light in an optical microscope.

Just as electrons have wave properties, light can also behave as if it is a collection of particles called 'photons'. This was established in 1905 by Einstein for an experiment involving the so-called 'photoelectric effect', and he was awarded the Nobel Prize for this work in 1921. We say that electromagnetic radiation (which includes light, as also X-rays, gamma-rays, etc.) exists as discrete packets of energy, or 'quanta', called photons.
 
Now consider an experiment in which an electron is more conveniently interpreted as behaving like a particle, rather than a wave. We can assign a position and a momentum (or velocity) to it. In a 1-dimensional situation, the position is, say, x, and the momentum is p_x. Let ∆x and ∆p_x be the errors or uncertainties in the measurement or specification of these quantities. In classical physics it is presumed that these errors or uncertainties can be arbitrarily small, even zero. This is not correct. Quantum physics attends to this wrong presumption of classical physics. There is this famous principle called the Heisenberg uncertainty principle, according to which the product ∆x.∆p_x cannot be less than a certain quantity of the order of the Planck constant, h. The principle says that ∆x.∆p_x ≥h/(4π). Of course, the Planck constant is a very very small quantity, but it is not zero.
 
This principle implies that if ∆x is nearly zero, then ∆p_x is extremely large, and vice versa. And large ∆p_x means large uncertainty in kinetic energy (because energy E = p_x²/2m, where m is the mass of the particle).

There are several 'conjugate' pairs of quantities for which the Heisenberg uncertainty principle must be obeyed. Energy E and time t are another such pair, and the principle states that ∆E.∆t ≥h/(4π). This provides a very important loophole (!) in the principle of conservation of energy, because the uncertainty principle says that energy conservation can be violated by an amount ∆E, provided it occurs for a time less than ∆t.

Back to the Big-Bang event. This was a quantum event because the spatial dimension of the system was extremely small: ∆x ≈ 0. And this, in turn, means that ∆p_x, and therefore ∆E, could become arbitrarily large at the moment of the Big Bang. Our universe was born out of such a quantum fluctuation.
 
This energy fluctuation got sustenance from the fact that the gravitational interaction was born at the same instance, and the rest of the story is as given in Part 2 of this series.
 
Admittedly, this is a simplistic narrative, but should be enough to convey to the lay person how something could emerge out of 'nothing', without having to postulate the pre-existence of a Creator.

For those who can stomach it, here is an excerpt from a book by Seth Lloyd (2006):

Quantum mechanics describes energy in terms of quantum fields, a kind of underlying fabric of the universe, whose weave makes up the elementary particles – photons, electrons, quarks. The energy we see around us, then  –  in the form of Earth, stars, light, heat  –  was drawn out of the underlying quantum fields by the expansion of our universe. Gravity is an attractive force that pulls things together. . . As the universe expands (which it continues to do), gravity sucks energy out of the quantum fields. The energy in the quantum fields is almost always positive, and this positive energy is exactly balanced by the negative energy of gravitational attraction. As the expansion proceeds, more and more positive energy becomes available, in the form of matter and light – compensated for by the negative energy in the attractive force of the gravitational field.

Carl Sagan Quotes from the Rig-Ved

Carl Sagan was one of the best known popularizers of science. He was an atheist. In this video he quotes from the Rig-Ved. Please click on 'YouTube' to view it.

Who Says Science has Nothing to Say About Morality?

Sam Harris is one of the original proponents of the philosophy of New Atheism (cf. my post dated 6 November 2011). Some of his books are: The End of Faith, Letter to a Christian Nation, and The Moral Landscape.

Please click on 'YouTube' to watch this video. It is a lecture by Sam Harris.

Sam refers to David Hume's distinction between 'is' and 'ought'. The 'is' part is clearly in the purview of science. But even the 'ought' part can come in when we realize that the well-being of the ecosphere is OUR responsibility entirely, and only scientific reasoning and methods can ensure this. Naturally, the justification for the maximum good of the largest number follows from this. The only way to be selfish sensibly is to care for the happiness of others. This 'science of morality' is a far cry from what passes as 'moral science' in religious teaching.

Some other points made by Sam Harris are: 

• It makes sense to raise compassionate children.
• It may be necessary to shun certain kinds of knowledge (in our pursuit of truth). This may be so for, for example, to forestall internecine wars.
• There is no need to postulate the existence of free will.
• Even subjective 'facts' can be subjected to objective analysis. 
• People can be wrong about their perceived subjective knowledge.
• Sometimes one has to weigh justice against fairness, and tilt a little towards fairness (even at the cost of absolute justice).

In short, scientific reasoning CAN be used for dealing with questions of morality. The scientific method is supreme. 

2. The Big Bang

How and when did our universe begin?

According to the most acceptable scientific model at present, our universe was born ~13.7 billion years ago. A so-called 'Big Bang' occurred at the moment of the birth of the universe, and this moment was also the Time Zero for our universe.

But how can something emerge out of nothing? Is that not a violation of the law of conservation of mass and energy? Was there not a Creator involved? No.

A proper explanation requires reference to what is called quantum field theory. But I shall attempt a simple explanation here, just to convey the point that there was no net creation or annihilation of mass/energy involved.

We all know about the force of gravity that the Earth exerts on all objects. If your mass is m, then your weight is mg, where g is 'acceleration due to gravity'. The mass is a measure of the quantity of matter. The weight is a force; the force the Earth exerts to pull you towards its centre. [Newton's second law of motion says that force is equal to mass multiplied by acceleration: F = m x a; and a is the same as g in our example.]

Your weight on the Moon would be one-sixth what it is on Earth because the Moon has a lower mass than the Earth, with a correspondingly lower value for its g.

The gravitational force or interaction is one of the four fundamental interactions of Nature. It is an attractive interaction (rather than a repulsive interaction). There is a force of gravitational attraction between any two objects. It is directly proportional to the product of their masses, and inversely proportional to the square of the distance between them. For example, if the distance is doubled, the gravitational force of attraction becomes one-fourth.

Consider an object (say of mass m₁) that is so far from everything that there is no gravitational force on it. This is really not possible, but just imagine it as an idealization. We say that it is a 'free' object, free from any gravitational force acting on it.

Next, consider another object, of mass m₂, at a certain finite distance from the first object. The two attract each other. Physicists speak of this as a negative-energy configuration, because (positive) energy needs to be spent to take the two objects so far away from each other that they are free of each other's force of attraction. By contrast, a positive–energy configuration would be one in which the two objects repelled each other, rather than attracting.

So, the gravitational interaction makes a negative contribution to the overall energy.

The other big idea I have to introduce here is that mass and energy are inter-convertible. This fact is embodied in the famous Einstein equation: E = mc². Here c is the speed of light in vacuum. The equation says that if a mass m disappears, an equivalent amount of energy E would be produced or released.

This is how energy is produced in our Sun (by thermonuclear reactions). The mass of five atoms of hydrogen (or rather an atom of 'deuterium' (which is twice as heavy as an atom of hydrogen) and an atom of 'tritium' (thrice as heavy as an atom of hydrogen)) is a little more than that of an atom of helium and a charge-neutral particle called the 'neutron'. In the interior of the Sun, conditions are right for the fusing of deuterium and tritium atoms, and the creation of an atom of helium plus a free neutron; the balance mass appears as energy. We receive some of this life-sustaining solar energy on Earth.

Similarly, in a fission-based nuclear reactor we produce energy by losing a little mass of, say, uranium. The nucleus of an atom of uranium captures a neutron to form a 'compound nucleus'. This then splits (fissions) to two different nuclei the sum total of the masses of which is a little less than the mass of the compound nucleus. The balance mass appears as kinetic energy (same as heat energy) of the particles involved.

What happened at the Big Bang was that there was a simultaneous emergence of the gravitational interaction. There was an explosion of sorts, in which radiation (and, a little latter, matter) emerged. The universe has been expanding ever since then. Expansion means an increase in the distances between the celestial bodies. Such ever-increasing distances mean a build-up of negative energy, which gets compensated by the creation of an equivalent amount of matter.

This is how mass gets created out of 'nothing', and there is no violation of the law of mass/energy conservation. This 'nothing' is actually a vacuum, which has some remarkable properties which can be described in the language of quantum mechanics only. Further, according to Einstein's theory of gravitation (to be described in a future post), the existence of a certain 'cosmological constant' can endow empty space with mass/energy.

But let us not get into those details yet. For the time being, suffice it to say that our universe emerged out of nothing, and this did not require the intervention of a Creator. The book by Hawking & Mlodinow explains that in some detail.

Of course, there are other models which compete with the Big Bang model, and the final word has not been said yet. Science is open to all ideas, subject to rational analysis and experimental verification. One such model postulates a cyclical set of events, involving an endless series of Big Bangs and Big Crunches. But then, in such a model, there is no need to argue how matter can emerge out of nothing.

Great Indians - 5

Darwinian Evolution

 Teach yourself Darwinian evolution. Click here for free downloads.

Our Duty Towards Children

Minds of young children are highly impressionable. They are strongly influenced by what they learn from their parents and teachers. It is only much later that some of them make a near-complete break from the childhood conditioning, and strike on their own. My own rejection of the unscientific and irrational way of thinking at the age of ~17 years is an example. But most people are not able to make this kind of a break. In particular, it is very difficult for them to undo the brainwashing regarding religion and God etc.

Ideally, enlightened parents should strive to create conditions in the family in which the child can grow to become an independent thinker, unencumbered by the views his/her parents or teachers may hold. Credulity in a child is an evolutionary necessity. It suits the child as well as the parents. But every child has a right to be exposed to all streams of thought before making a choice.

Imagine a scenario in which a child learns to have full confidence in the scientific method, and therefore in science. Such a person will not waste energy and time fighting what science has to say. Instead, he/she will take even the counter-intuitive quantum mechanics for granted, all the time fully conscious of the fact that there is nothing dogmatic about the concepts and theories of science, and even the most cherished scientific ideas can be abandoned if the new evidence so demands. Such a person will be able to have a rational and objective view about the (failed) hypothesis about God, even when he/she does not have the expertise to understand the advanced scientific ideas used in, for example, Hawking's book I mentioned in the previous post.

The present situation is pathetic and alarming. In India, in most cases even a six-month old child gets exposed to religious mumbo jumbo. Around that age the child gets the first solid food and, sure as ever, the event abounds in religious ('auspicious') trappings.

What right the parents have to impose their views on a child? The child should be able to make a choice after learning about the various streams of thought. Is that asking for too much? Are we being fair to our children?

Needless to say, the parents do it with good intentions. Most of them believe that a religious upbringing will instill moral values in the child. But do they succeed? I don't think so.

How moral is it to kill in the name of religion?

How moral is it to perpetuate social injustice in the name of religion?

How moral is it to stifle the intellectual growth of a child in the name of religion (e.g. by teaching creationism)? If you teach your child that something is true simply because the 'holy book' says so, you are destroying something very valuable, namely the urge to go on questioning things till a rational and sensible answer has been obtained.

How moral is it for parents to teach a child that their religion (or caste) is superior to all others?

I can go on.

Now contrast this with a situation in which a child has imbibed the spirit of the scientific method, and has blossomed into a rational, mature person who realizes that there is no God up there to intervene and help us in case we mess up our affairs on this planet. That Mother Earth is our collective responsibility, for which we should cooperate with one another, rather than waste our energy and resources in mindless conflicts in the name of religion.

Imagine a world in which human beings, after they grow up from childhood, are no longer children in their emotional get-up, but are mature, responsible, and mentally strong persons, who hold nobody but themselves accountable for all their actions. They do not need a father figure (God) to whom to go crying for help like a child does. They are noble and moral because it feels good to be so, rather than because they believe that God will punish them if they are not good. And what kind of God is this which first makes people do what he wills, and then punishes them for their actions?

By adopting a strictly logical, honest, and objective approach to empirical observations and data, humanity has been able to achieve so much. To appreciate this properly, and to take pride in our scientific heritage, your child should understand the basics of this approach. In particular, he/she must learn to admire the indomitable human spirit which, in spite of the hostile conditions in which it had to progress, came up on top by adopting THE SCIENTIFIC METHOD of interpreting natural phenomena.

‘Science is the process that takes us from confusion to understanding in a manner that’s precise, predictive and reliable – a transformation, for those lucky enough to experience it, that is empowering and emotional’ (Brian Greene).

Do you really want to deprive your child of this empowerment, and cripple his/her mental growth? Think about it.

Richard Dawkins has recently written a book, The Magic of Reality, which explains to children how the scientific version of reality has far more magical beauty and fascination than any of the prevailing myths about reality.It is designed to be intelligible to 12-year olds, perhaps with some help from enlightened parents. How about buying a copy of the book for your child?

With or without religion, good people can behave well and bad people can do evil; but for good people to do evil - that takes religion [Steven Weinberg (Nobel Laureate).]