The Science Book

200

W

hile the 19th century
had seen a fundamental
change in the way
scientists view life processes,
the first half of the 20th would
prove even more of a shock. The
old certainties of classical physics,
largely unchanged since Isaac
Newton, were about to be thrown
away, and nothing short of a new
way to view space, time, and
matter was to replace it. By 1930,
the old idea of a predictable
universe had been shattered.

A new physics
Physicists were finding that the
equations of classical mechanics
were producing some nonsensical
results. It was clear that something
was fundamentally wrong. In 1900,
Max Planck solved the puzzle of the
spectrum of radiation emitted by a

“black box,” which had stubbornly

resisted classical equations, by

imagining that electromagnetism

traveled not in continuous

waves, but in discrete packets,

or “quanta.” Five years later,

Albert Einstein, a clerk working

at the Swiss Patent Office,

produced his paper on special

relativity, asserting that the

speed of light is constant and

independent of the movement of

source or observer. After working

through the implications of general

relativity, Einstein had found by

1916 that notions of an absolute

time and space independent of the

observer had gone, to be replaced

by a single space-time, which was

warped by the presence of mass

to produce gravity. Einstein had

further demonstrated that matter

and energy should be considered

aspects of the same phenomenon,

capable of being converted from

one to the other, and his equation

describing their relation—E = mc^2

—hinted at an enormous potential

energy locked inside atoms.

Wave–particle duality

Worse was to follow for the old

picture of the universe. At

Cambridge, English physicist

J. J. Thomson discovered the

electron, showing that it has a

negative charge and is at least

a thousand times smaller and

lighter than any atom. Studying

the properties of the electron

was to produce new puzzles.

Not only did light have particle-like

properties, but particles had

wavelike properties, too. Austrian

Erwin Schrödinger drew up a

series of equations that described

INTRODUCTION

1900

1905

1915

1926

1906

1912

1927

Thomas Hunt Morgan

introduces the

chromosome theory

of inheritance.

Albert Einstein produces

his paper on special

relativity.

J. J. Thomson is awarded

the Nobel Prize in Physics

for his discovery of

the electron.

Paul Dirac introduces

quantum

electrodynamics.

Alfred Wegener

proposes a theory of

continental drift.

Max Planck describes

discrete packets, or

quanta, of energy.

Werner Heisenberg sets

out his uncertainty

principle.

Erwin Schrödinger

unleashes wave

mechanics.

1928