Sunday, February 8, 2009

Book Review: A Brief History of Time

A Brief History of TimeOne of my favourite books is A Brief History of Time, written by Stephen Hawking. This book is famous like its author. Its wonder lies in the fact that the forefront of physics is portrayed in laymen's terms. Thus the theories behind quantum mechanics, relativity, black holes, time travel, and wormholes can all be comprehended by the average person. Every time I pick up this paperback, I feel humbled by the grandeur of our mysterious universe. Needless to say, the origin of the universe may just provide a clue to the birth of life. Of all the theories described in the book, I was most intrigued by Einstein's special theory of relativity.

Before the dawn of the 20th Century, the Michelson-Morley experiment was conducted to substantiate the existence of a substance called "ether." Instead, it created a shock wave for the entire scientific community. Throughout the next twenty years, numerous futile attempts were made to explain the surprising results of the experiment. In the end, it was Einstein's special theory of relativity that came to the rescue.

A remarkable consequence of relativity is that it revolutionized our ideas of space and time. Before Einstein's heydays, Newtonian physics indicated that space was not absolute, meaning different observers of a moving object may conclude differently about the distance it travelled. However, time was always assumed to be absolute, i.e., different observers would always agree on the time it took an object to traverse through space. Einstein took Newton's theories and took a step back. He claimed that if one lets go of the idea of absolute time, then we need not "invent" the idea of ether. Nor would we be troubled by the Michelson-Morley experiment. The notion of absolute time, however, is so deeply engraved in our minds that even today, it is difficult to discard.

Einstein went on to come up with unconventional predictions of how objects behave when they approach the speed of light. These imaginary experiments came to be known as Einstein's paradoxes. Perhaps the most famous one is the twins paradox: A twin steps on a spaceship and travels at the speed of light for 20 years according to his watch. When he returns to Earth, he will find that much more time has indeed elapsed during his absence and his twin brother is now 100 years older than him. You might find it hard to accept this outcome. That is why it is called a paradox in the first place. However, this is not so difficult any more if you think of time being relative.

Einstein's brilliance in my opinion, lies not in his discovery of relativity, but the manner in which he did it. In order to reach his conclusions, he took a step back from well known physics principles. Instead of taking for granted the firmly-entrenched view that time was absolute, he chose to doubt it. In the end, he took a completely opposite stance. As a result, every road block baffling the scientific world then was instantly removed.

Einstein's work prompted me to wonder whether we can always take our assumptions for granted. Sometimes, moving a step backwards and re-evaluating popular opinion is not a bad idea. Of course, to his credit, Einstein also applied immense creativity and ingenuity to secure the fantastic success that he enjoyed. Nonetheless, I will keep this lesson in mind on my quest for knowledge.


-PTS

4 comments:

  1. Very nice!
    Thank you.
    (I arrived from Wired via WUWT?)

    ReplyDelete
  2. Of course this book is great... its been the best selling science book for the longest time!

    ReplyDelete
  3. I didn't care for the book. It accepted so much nonsense ideas the physicists tout.
    M&M's experiment could not possibly have given any results related to the ether (illogical experiment design!).
    Then Fitzgerald came up with a formula to apply to the calculations that would set it right. Eventually Einstein adopted the formula into his relativity theory, but no reason was given to support such an action. Then Einstein came up with some more ridiculous ideas, such as that the mass of an object increases with its speed (but from what cause?). Then they get no time and curved space. What wll be next?

    ReplyDelete
  4. @Ralph: I agree that Einstein's ideas are radical and hard to accept at least at first, but so are all bleeding edge concepts (science and what not). I am not standing 100% behind Einstein or Hawkings, as I believe their theories (as with all theories) can be disproved and replaced with better theories. After all science is all about "best guesses", and we call these guesses "theories".

    ReplyDelete