By Chet Yarbrough
Narrated by Michael Jackson
In a physics reference table, A Brief History of Time is an old book because it dates before the year 2000. However, it remains a fairly good layman’s overview of the state of physics.
This surprise best seller is not easy to understand in spite of its brevity and avoidance of mathematics. Without additional reading, “A Brief History of Time” is less intelligible than more recent physics-for-laymen’ books (see previous reviews).
An interesting and revealing observation in Hawking’s book is a comment about the lack of philosophical perspective in the field of Physics. Hawking suggests that philosophers choose not to examine theories of physics because of the abstruse and specialized nature of research that make it difficult for outsiders to understand. There is some truth in that observation but one can read Will Durant’s 1929 edition of “The Mansions of Philosophy” or his revision (“The Pleasures of Philosophy”) in 1953 and see that Durant believed philosophy was in decline long before specialized research in physics.
Hawking explains that Einstein shows time is not a constant measurement for all observers. Time is relative. Depending on one’s speed of travel, measurement of time is different for individuals traveling at different speeds. A person traveling nearer the speed of light sees time pass slower than a person who is traveling at a slower rate of speed. Humans do not see time slow down or speed up at conventional speed differentials because the differences in time are too small for human perception.
If a human travels near the speed of light, he/she ages slower than a person traveling at earth-bound speeds. The theory suggests humans can travel into the future but not into the past. As a person slows from the speed of light, observation would show that people he/she knew were older, if alive, than when last seen.
The world appears as a different place to the speed-of-light traveler. Everything would look different to the speed-of-light’ traveler that slows down, with the amount of difference based on how long he/she had been traveling at the speed of light while the rest of the world was traveling at normative speeds.
Black holes are high density, gravitational points in the universe that are so powerful that anything within their grasp (their event horizons) will be sucked into their maws, never to be seen again. The belief is that black holes (though not actually black) come from imploding stars; i.e. stars that have lost their source of nuclear reaction that become so dense that their force of gravitation draws anything near them into their mass.
Hawking believes time began when our universe exploded from a single point in the cosmos. Before the big bang, there was no concept of time. Our universe is expanding from that singular event and will do one of three things. It will continue to expand, it will expand to a point and then contract, or it will reach a point of stasis.
The question of the existence of God is raised and unresolved.
The quest for a unified field theory is part of a physics reference table that began with Newton, progressed through Einstein and Dirac, and is presently stalled at string theory speculation. The search continues, passing to future generations. Finding a unified field theory, in Hawking’s opinion, would be like reading the mind of God.