Book Club: Simply Einstein, Relativity Demystified

We each take turns writing our blog posts for the office book club. This entry was from Bart Epstein. In January, our  book club read Simply Einstein: Relativity Demystified, by Richard Wolfson.

The consensus on this book was nearly unanimous – it was the hardest book we have read by far, but also one of the best, most interesting, and most thought-provoking.   Reading a book like this really highlighted the difference between reading literature for pure pleasure and reading non-fiction to learn complex concepts.  Both can be rewarding experiences but they use completely different parts of our brains.

Mark thought this was the best book we read so far, and I liked this book so much that after returning my borrowed copy to the library I purchased a copy for my bookshelf.   I will freely admit that I had to re-read several sections of the book to allow the concepts to make sense.

The topic of the book is Einstein’s Special Theory of Relativity, which is difficult for most of us to comprehend because it deals with physical phenomenon that manifest themselves most observably at speeds we have never experienced — many thousands of miles per second. Because nearly everything we know and experience on Earth travels far less than even a single mile per second (3,600 miles per hour), we simply don’t experience the effects of relativity, and therefore find them difficult to comprehend.

In many ways, trying to teach humans about relativity is similar to explaining to snails how race cars zooming around a track need a very steep banked wall during the turns, to counterbalance centripetal acceleration.  Any human who has ever watched a NASCAR race (or exited a highway at high speed) understands this principal intuitively.

simply einstein relativity demystified

But most snails never would likely be completely puzzled by the concepts of inertia and acceleration and banked curves, because any snail that moves faster than one foot per minute is a likely candidate for the land speed record for snails.  And centripetal forces at such small speeds are simply not noticeable, regardless of how smart the snails may be.

simply einstein relativity demystified

And so it is for us humans who, as Adam pointed out in our book club discussion, think that “space” and “time” are two completely different concepts, when the reality of the universe is that space and time are both manifestations of a single concept called spacetime.  In his book, Wolfson does an excellent job of explaining how Einstein built on the work of Newton and others to eventually realize that time is not a universal constant but rather is inextricably intertwined with space.

The classic analogy used to explain how massive objects curve spacetime (and cause the perception of gravity) is by causing an indentation on a flat surface, such as in this picture of the sun.  The analogy is incomplete, however, because spacetime is four dimensional and we lack the tools to properly represent four dimensions in a two-dimensional medium such as a book or webpage.  (We also learn that gravity isn’t a force like magnetism but rather is a simple consequence of the topology of spacetime being curved and distorted by massive objects.)

simply einstein relativity demystified

What this means as a practical matter is that when someone travels at thousands of miles per second, time slows down.   Not from the perception standpoint, as in “I’m bored this class is taking forever,” but in the real physical tangible sense that the passage of time itself changes and slows when someone (or an object) is moving near the speed of light of 186,000 miles per second.

This concept is mind-boggling when you understand that for a person moving near the speed of light (relative to us on Earth) their clock is not “running slow.”   To an observer traveling at three quarters of the speed of light, time seems to “run” normally.   But time is “passing” for him at a much slower rate than for everyone else on Earth.

Wolfson does a very nice job of expanding on Einstein’s famous explanation about what would happen to a pair of identical twins when one took a trip on a spaceship traveling at near the speed of light, to another star, and then returned years later:  From the perspective of the space-traveling twin, only five years have passed.   But when he returned home he would find that his brother had experienced and aged twenty years because time itself is not a constant – the speed at which time “ticks” varies depending on one’s speed relative to another.    Both twins experience time normally in their local space but their entire frame of reference experiences time differently.

simply einstein relativity demystified

My own analogy is to think of two boats on an ocean, hundreds of miles apart.    Both boats have their motors on and are moving northeast at 5 miles per hours, but one boat is floating in the middle of the Gulf Stream, which is also moving northeast at 5 miles per hour.

As I said, this concept is mind-boggling, because we on Earth all experience time moving at the exact same speed “through time” because we are all essentially at rest when compared to the blazingly fast speed of light.

Wolfson also does a nice job of explaining how, because space (distance) and time are not separate principles but rather are both part of “spacetime,” it is equally valid to say that “distances” change as it is to say that “time” changes.  Wolfson is a patient, methodical writer who does an admirable job of explaining one of the most astonishing concepts in science without resorting to high level math or mumbo jumbo.    This equation is about as hard as it gets and he spends several pages breaking it down and explaining it.

simply einstein relativity demystified

In terms of other feedback and thoughts, Erica said she likes these kinds of books because it reminds her how little we know (as a species) and how much learning is ahead for us.   We tend to think of ourselves as modern and advanced as compared to those ignorant fools a thousand years ago who knew nothing of cars or electricity or even basic medicine.   But I have little doubt that people 500 years from now will look back at our times and shake their heads at how primitive and confused we were.

The book also discussed how black holes are formed and behave.  Kate loved that part, especially thinking about how a teaspoon of a black hole could weigh trillions of tons.  (Be sure to use two hands to hold it!)

Related to this concept, we discussed recent data collected by astrophysicists that calls into question the current belief that before our universe came into existence there was pure nothingness.  No time, no space, no nothing.   Within the last few weeks a pair of prominent researchers may have found evidence of echoes from a “big crunch” that happened before the big bang that created everything we know.  They theorize that “our universe may ‘be but one aeon in a (perhaps unending) succession of such aeons.’ What we think of as our ‘universe’ may simply be one link in a chain of universes, each beginning with a big bang and ending in a way that sends detectable gravitational waves into the next universe.” (Source, NYT.)

Adam really liked the idea of our entire universe recycling – starting with a big bang, billions of years of expansion and life and adventure, followed by a huge crunch as ever last stitch of spacetime and all matter and energy crunch back into a singularity. . .  which causes another big bang and so on forever.

Mark pointed out that it is nearly impossible for us humans to fathom there being a time before time … a time where there is no time.   He is certainly right, and we find that concept nearly impossible to fathom because time is such a constant in my life.   But it does appear that time is neither constant nor universal, except when waiting for a pot of water to boil or for a crying baby to fall asleep.

For our next book we switch gears.  Lauren has picked a widely acclaimed novel of historical fiction called Parrot and Olivier in America, by Peter Carey, an imagining of the experiences of Alexis de Tocqueville, the great French political philosopher who wrote Democracy in America.    If anyone would like to read along with us and email in thoughts or ideas or questions we’ll be glad to throw them into the mix when we next meet.

4 Responses to Book Club: Simply Einstein, Relativity Demystified

  1. Mike March 23, 2011 at 2:36 AM #

    If you believe in relativity and time dilation, try to answer this question:

    Suppose we have a long road. every 150,000 km (93,000 miles) along the road there is a clock, and above it a high resolution camera. The clocks are numbered, 1, 2, 3….100. All clocks are synchronized.

    A car is riding along the road, at half the speed of light (150,000 km/sec) relative to the road. On its roof a big clock, and a high resolution camera.
    Every time the car pass by a clock, the cameras in the car and on the road takes a picture of both clocks: the one on the road and the one in the car.
    The question is: If at clock #1 on the road, both pictures from the cameras, the one on the road and the one on the car, will show exactly 09.00.0000000, what will they show in clock 2, and 3?

    If you think that there is time dilation, remember that relative to the car, the road is the one which is moving, and since unlike the twin paradox, no acceleration is involved, which clock will slow down?

  2. sobelabs review February 21, 2011 at 9:16 PM #

    Good post which post reduced the problem a whole lot with my class assignment.

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