
George Gamow (19041968)

George
Gamow was a brilliant physicist who made major contributions
to 20th century physics. He worked with Niels Bohr in the development
of quantum mechanics. During World War 2 he participated in the
Manhattan project. After the war he became one of the chief advocates
of the Big Bang theory. He was also a great popularizer of science
with a wonderful sense of humor. (On one occasion,
when he was about to publish a paper with his student Ralph Alpher,
he mischievously added Hans Bethe's name to the paper, although
Bethe had had nothing to do with it, just to make a pun on alphabetagamma.)
He has written several books on physics for laymen
in addition to his Mr. Tompkins books, such as One, Two, Three
 Infinity and Thirty Years That Shook Physics.
In "Mr. Tompkins in Wonderland" his protagonist
is a bank clerk who strays into a physics lecture. Of course, Mr.
Tompkins does not understand much of what the professor is saying
 his skills in mathematics are limited to addition, subtraction,
multiplication and division, "of which he uses the first two
in his profession". But he picks up enough interesting impressions
to have a vivid dream related to the lecture. He likes his dream
and comes back to enjoy additional lectures which in turn inspire
new dreams.
In
his dreams, Mr. Tompkins experiences some of the weird and counterintuitive
phenomena of the theories of Relativity and Quantum Mechanics. Gamow
uses the ingenious device of lowering the speed of light to 15 km/h
and of raising the value of Planck's constant by many orders of
magnitude in Mr. Tompkins dreams. The result is that relativistic
and quantum effects become noticeable in daily life. For instance,
Mr. Tompkins experiences length contraction in his surroundings
when he travels fast on his bike; and when he plays billiards, the
balls spread out in a probability cloud after each collision. The
lectures that trigger his dreams are included as appendices to the
book.
Actually, notwithstanding the awe that surrounds Albert Einstein
and his work, the Special Theory of Relativity published in 1905
is not that difficult to understand. It is certainly within
the capacity of many bright 15yearolds. It is just a question
of working out the logical consequences of the empirical observation,
that a measurement of the speed of light in vacuum always gives
the same result, irrespective of the relative motions of the observer
and the observed object. The difficult part is to integrate this
with your "gut feeling" about how the world works.

The stowaway running at 0.75 c on a train
travelling at 0.75 c still cannot outrun the beam of light.

In the late 19th century, it was quite a shock to scientists to
find that the speed of light is constant to all observers. They
tried to measure our planet's speed relative to the "ether",
the medium that was believed to carry light waves, by sending light
in different directions and having it reflected by mirrors, over
carefully measured distances. The negative result was hard to explain.
 Today we do not have to rely on tricky measurements to know that
the speed of light is constant. In supernova explosions, large parts
of a star are ejected in opposite directions at speeds of thousands
of km/sec, i. e. at a significant fraction of the speed of light.
If the speeds of those segments were additive/subtractive to the
speed of light, we would expect a supernova explosion to be visible
for centuries rather than weeks or months.  Direct measurements
of the speed of light can nowadays be carried out with extremely
great precision. The unit of length, the meter, has been formally
redefined as the distance that light travels in 1/299 792 458 of
a second.

Mr. Tompkins waking up
from one of his dreams.

Einstein's greatest achievement was the General Theory of Relativity
in 1915, ten years after he published his Special Theory of Relativity.
While the Special Theory of Relativity deals with reference systems
travelling at uniform speed relative to one another, the General
Theory of Relativity concerns systems that accelerate with respect
to one another. The starting point is two key observations: 1. Inertial
mass is identical to "weighed" mass. The effects of gravity
and of acceleration are identical. (Einstein described a thought
experiment involving an accelerating elevator to demonstrate this.)
2. If one frame of reference rotates with respect to another, application
of the Special Theory of Relativity leads to the conclusion that
the geometry of the rotating system cannot be Euclidean.  The full
implications of this are not as easy to deduce as in the case of
Special Relativity, but Einstein was able to make two specific predictions
that set his theory apart from Newtonian physics: a) Light bends
around massive objects, so the apparent position of stars will shift
slightly near the sun (observable during a total eclipse). b) The
orbit of Mercury will precess in a way that can be precisely predicted.
 Both of these predictions were confirmed within a few years.
The dreams of Mr. Tompkins make an enjoyable path to understanding
Relativity, but Einstein himself was quite good at explaining his
theories to an educated lay audience, as can be seen from his book
Über die spezielle und die allgemeine Relativitätstheorie published
in 1916. An English translation is available here.  When it comes to Quantum Physics,
Einstein's role was more that of "the Devil's Advocate".
(See my musings about Quantum
Entanglement.)
An amusing aside: When my schoolmate and close friend
Olav and I were 14 or 15, we went into an 8storey building near
our school just to ride the elevator up and down. (Elevators were
a rarity at the time; there were few highrise buildings in our
suburb of Stockholm.) When an annoyed adult asked what we thought
we were doing, Olav responded: "We are conducting Einstein's
elevator experiment!". (Olav
Kallenberg later had a career as a professor of probability
theory at Auburn University.)
"Books"
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