I was once challenged by a friend: ‘I have just finished reading Stephen Hawking’s “A Brief History of Time” and I have no clue what I just read. Can you send me a half page summary of the book’.
So, here…
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‘Is space infinite? And in what sense? Is the material world infinite in extent, and are all places within that extent equally full of matter? Do atoms exist, or is matter infinitely divisible? The discussion of questions of this kind has been going on ever since men began to reason, and to each of us, as soon as we obtain the use of our faculties, the same old questions arise as fresh as ever.’
-James Clerk Maxwell (1831-1879,) Physicist and Mathematician
Famous for his work on electromagnetism
In his book, a Brief History of Time, Physicist and Mathematician, Stephen Hawking presents to the reader a picture of the Universe in which we live in. In the book, he discusses some of the latest developments in science, especially Physics, in the latter half of the century. He hasattempted, and succeeded in explaining a range of topics from Astrophysics andCosmology and Quantum Mechanics including topics such as The Big Bang Theory, Black Holes and developments in Quantum Mechanics and the Physics of sub atomic particles. Thebook is about the history of time itself, so in this summary, I will dwell on this interesting quantity.
It was shown by Einstein in 1905, in his theory of Special Relativity that time is the fourth dimension. Time can move faster, or slow down, for different objects relative to their motion. Objects exist in space, that is, length, width and height. For instance, we say that an object is so many metres long, several metres wide and several metres high. That is volume in space. Einstein, however, showed that that time itself is not an absolute and constant quantity. For instance, Time slows down at very high velocities (as an object approaches the speed of light, this difference in time is not negligible). Since different objects in the universe have different velocities, they also have their own unique times. That is to say, an object exists in the three dimensions in space, plus another dimension – time. A bird lasts for a length of say one year, a tree lives for say fourty years, a stone for say, 10000 years, and fools will exist for, say, eternity. After the relativity theory, the idea of Space-time was (officially) born. Three-dimensional geometry was no longer possible to describe our universe. Space-time was represented by four-dimensional geometry. This may be a little confusing at first, but, not to worry, three dimensional geometry is good enough for describing our or day to day phenomena but it issomewhat inaccurate when describing events at the sub atomic level, or when describing objects moving at nearly the speed of light. Now, since it is possible to move along the three dimensions in space, it is also (theoretically) possible to travel through time in Space-time. Hawking explores the possibility of time travel in the book, and, in future, if mankind is advanced enough to travel through time, the form in which time travel will take.
It is generally believed that the Universe was created froma singularity (a point in space-time with infinite ‘density’ during The Big Bang. The Big Bang, it is thought, happened about 13.7 billion years ago. Time began at the Big Bang. Time is a quantity that was created along with everything else in the present Universe, including our laws of Physics – the laws with which we use to describe our Universe. There would be no way to ‘know’ what it was like before the Big Bang. At least, there would be no way of describing or re-creating those events mathematically.
So, if time began at the Big Bang, then it can be said that Time itself has a history (or herstory for thegender sensitive). I think that is one of the reasons Hawking chose ‘A brief History of Time’ as the title for his epic scientific book. If you like science, or you like asking big questions about our Universe, this is a book that I would recommend you read. (And, it is science book, so one would expect some math and equation in there, Hawking doesn’t dissappoint, he includes an equation in the book, the only equation: E=mc^2).
Now, does time have a beginning? Is it possible to travel through time to say, a different parallel universe in which there are different realities? Was the universe formed/created some 13.7 billion years ago during the Big Bang? Something tells me no. I think that there was no Big Bang.
My half a page of space has ran out.
Reference
You may download the ebook, ‘A Brief History of Time’ by Stephen Hawking at: