A Brief History of Time by Stephen Hawking

We have all asked ourselves the question of where the universe came from, and sometimes we also ask where it will end up. Then we decide to focus on just “ordinary” life on earth, forgetting that this very earth is spinning. It spins (rotates) at a speed of about 1,000 miles (1600 kilometers) per hour and orbits around the Sun at a speed of about 67,000 miles (107,000 kilometers) per hour. But we don’t feel it because the earth rotates and revolves  at a constant speed. We only feel motion when there is a change in speed.

Our Solar System

Gravity

If we are a giant ball spinning so fast around in space, what is keeping us there? Why aren’t we drifting away from the sun, crashing into other planets etc? We can all thank the law of gravity for that. Although it is a “weak force”, it exerts itself across long distances and it is always attractive, that is objects with mass will always attract one another with the force of gravity. The planets in our solar system are all caught up in the sun’s gravity so they all orbit it. But they orbit it at such a speed as to balance the force of gravity that would otherwise cause them crash into the sun. If  the speed were any faster too, the planets would overcome the force of gravity and drift further away.

If we zoom out of our solar system, the milky way and other galaxies around us are also observed to be constantly moving, at this critical speed that balances gravity. But is the observable universe  drifting farther apart? So it seems. If the universe is drifting apart, could this imply that at some time in the past it was all “together” at a singularity, at the point of the big bang. What is a singularity, exactly? Well, Stephen Hawking tries to explain in his book. Can gravity be so strong that it attracts the matter in a body and condenses into such high density that nothing can escape from it?

A black hole in space

 

This leads to the subject of black holes. There is matter out there in the universe that we cannot see, but we can see its effects because observable matter revolves around it. For example, if we see a star seemingly orbiting empty space, this “empty space” implies there is matter there but we cannot see it because gravity  is so strong nothing can escape from it, not even light. What is at the center of a black hole, if for example you fell into one? At the center of a black is a singularity, a point in which all the laws of physics break down and thus there is no telling what happens then.

The Strong Forces 

Over time, scientists have discovered the other forces in the universe. Physics was on “two levels”, the macro level observing the universe out there, and the micro level examining subatomic particles. In high school physics, we were taught that the smallest particles are electrons, protons and neutrons (these 3 make up an atom, which in turn make up a molecule). However, protons and neutrons are made up of even smaller particles called quarks! Are there even smaller particles than that? It does not seem so. But are there undiscovered subatomic particles? It seems so!

The Higg’s Boson, the origin of the World’s Mass. Image from http://4.bp.blogspot.com/

Recently in the news, there was the news of the particle accelerator (the machine they use to break up protons into even smaller particles) in Switzerland receiving an upgrade so that the super smart scientists can observe a particle known as the Higg’s Boson. We were taught in school that protons and neutrons contain mass and so are much heavier than electrons, but it turns out that protons and neutrons too, don’t have any mass! They pick up the mass property when they interact with the Higg’s field. The particles that make up the Higg’s field are called the Higg’s Boson. (This part about Higg’s Boson is not in this book actually, because it was published in 1988 – the year I was born. Stephen Hawking also wrote The Grand Design in 2010, which is definitely more updated and which I hope to read next).

(I hope there is someone still reading this!)

Okay, there is the force that keeps protons and neutrons together in the nucleus of an atom. This is called the strong nuclear force and that is why we need a lot of energy, achievable via the particle accelerator (the size of the largest one is 175Km in circumfrence lying 175 meters below the ground) to break apart protons and neutrons.  There is the weak nuclear force that keeps the quarks stable (don’t ask me to elaborate!).

There is the electromagnetic force that is observable all around us. At first it was thought that electricity and magnetism were two different forces until an English Scientist known as John Maxwell showed that they are like two different forms of the same force. Light is an electromagnetic wave, for example.

Stephen Hawking explains these forces more in his book, but fear not, there is no single equation except  E=mc²  pioneered by Einstein, he who came up with the theory of relativity. I kind of wish the equations were there (I am not sure I will understand them!) but actually equations are just symbols to explain “complex” thought. Imagine saying “eight times five is equal to forty” instead of” 8 X 5 = 40. ” He has to explain the equations in simple words for us to understand the complex physics theories!

The Unification of the Forces

So at the current energies of the universe, we have all these sub-atomic particles, and all these forces (that are carried by subatomic, force-carrying particles). However, at some critical energy, all these particles will lose their uniqueness and act as the same particle, the same force. This is called the grand unified theory which occurs at this high energy which unifies the three forces: weak and strong nuclear forces, and the electromagnetic force.

But this leaves out gravity.

Unification of physics

To incorporate gravity, the equations get extremely complex. The string theory is one of those theories trying to unify the 3 forces with gravity. Hence the “macro”  and “micro” physicists are now working together, it is the unification of physics. For the string theory to work however, it would mean that the universe is composed of up to 26 dimensions! We can barely process 3 let alone 4 or more dimensions!

There is so much more fascinating stuff in the book, such as warm holes, singularities, quantum mechanics, black holes, dark matter (and dark energy?), does God have any role at all in the creation of the universe (maybe he made the laws that govern the universe but so far he has had little interference since then), what role did Galileo Galilei, Aristotle, Sir Iscaac Newton, Einstein and many more others play in the development of physics up to the modern age?

The problem with science (and knowledge) today is that it has got so complex that to understand it, you have to dedicate your entire life to just one small part of it. But this book opens up the world of physics in a new and exciting way, makes me feel like computer science is boring in comparison! The book is “simplified” and quite exciting to read, just read through the parts you don’t understand and marvel at the ones you do!

As you will see, this book is not against God as the creator; on the contrary Stephen Hawking realizes that scientists are just answering the “what” questions. What makes the earth revolve around the sun? It does not answer “why”, why should the forces of gravity even exist in the first place? Why should a universe exist in the first place such that the laws that govern it then exist? However, that God created man literally? You may have to rethink that, given the overwhelming evolution theory and scientific facts. It is my belief that the Bible should be revised to reflect the new knowledge we have uncovered in recent times. After all, we do revise our textbooks whenever we discover something new!

A Brief History of Time by Stephen Hawking

Anyway, this book is a recommended reading for all who can read!