The Science Book

216 ALBERT EINSTEIN

I

n the year 1905, the German
scientific journal Annalen der
Physik published four papers
by a single author—a little-known
26-year-old physicist named Albert
Einstein, then working at the
Swiss patent office. Together, these
papers would lay the foundations
for much of modern physics.
Einstein resolved some
fundamental problems that
had appeared in the scientific
understanding of the physical
world toward the end of the
19th century. One of the papers of
1905 transformed understanding

of the nature of light and energy.

A second was an elegant proof

that a long-observed physical

effect called Brownian motion

could demonstrate the existence

of atoms. A third showed the

presence of an ultimate speed limit

to the universe, and considered the

strange effects thereof, known as

special relativity, while the fourth

forever changed our understanding

of the nature of matter, showing

that it was interchangeable with

energy. A decade later, Einstein

followed up the implications of

these latter papers with a theory

IN CONTEXT

BRANCH

Physics

BEFORE

17th century Newtonian

physics provides a description

of gravity and motion, which

is still adequate for most

everyday calculations.

1900 Max Planck first argues

that light can be considered to

consist of individual packets,

or “quanta,” of energy.

AFTER

1917 Einstein uses general

relativity to produce a model

of the universe. Assuming

that the universe is static,

he introduces a factor called

the cosmological constant

to prevent its theoretical

collapse.

1971 Time dilation due

to general relativity is

demonstrated by flying

atomic clocks around the

world in jet aircraft.

of general relativity that presented

a new and deeper understanding

of gravity, space, and time.

Quantizing light

The first of Einstein’s 1905 papers

addressed a long-standing problem

with the photoelectric effect. This

phenomenon had been discovered

by German physicist Heinrich

Hertz in 1887. It involves metal

electrodes producing a flow

of electricity (that is, emitting

electrons) when illuminated by

certain wavelengths of radiation—

typically ultraviolet light. The

If the speed of light through a vacuum is

unchanging...

Observers in relative motion to each other

experience space and time differently.

Special relativity shows that there

is no absolute simultaneity.

Then there can be no absolute

time or space.

And the laws of physics appear the same

to all observers...