最初的三分钟.pdf

: .
t what the
universe was like at the end of the first second or the first
minute or the first year. To a physicist, the exhilarating
thing is to be able to work things out numerically, to be able
to say that at such and such a time the temperature and
density and chemical composition of the universe had such10 The First Three Minutes
and such values. True, we are not absolutely certain about
all this, but it is exciting that we are now able to speak of
such things with any confidence at all. It was this excitement
that I wanted to convey to the reader.
I had better say for what reader this book is intended.
I have written for one who is willing to puzzle through some
detailed arguments, but who is not at home in either mathe-
matics or physics. Although I must introduce some fairly
complicated scientific ideas, no mathematics is used in the
body of the book beyond arithmetic, and little or no knowl-
edge of physics or astronomy is assumed in advance. I have
tried to be careful to define scientific terms when they are
first used, and in addition I have supplied a glossary of
physical and astronomical terms (p. 165). Wherever possible,
I have also written numbers like 'a hundred thousand million'
in English, rather than use the more convenient scientific
notation: 1011.
However, this does not mean that I have tried to write an
easy book. When a lawyer writes for the general public, he
assumes that they do not know Law French or the Rule
Against Perpetuities, but he does not think the worse of them
for it, and he does not condescend to them. I want to return
the compliment: I picture the reader as a smart old attorney
who does not speak my language, but who expects nonethe-
less to hear some convincing arguments before he makes up
his mind.
For the reader who does want to see some of the calcula-