50th
Annual Meeting of the Australian
Mathematical Society
Education
Afternoon Talk
Terence
Tao (University of California,
Los Angeles)
The Cosmic
Distance Ladder
How do we know the distances from
the earth to the sun and moon, from the sun to the other planets,
and from the sun to other stars and distant galaxies? Clearly
we cannot measure these directly. Nevertheless there are many
indirect methods of measurement, combined with basic high-school
mathematics, which can allow one to get quite convincing and accurate
results without the need for advanced technology (for instance,
even the ancient Greeks could compute the distances from the earth
to the sun and moon to moderate accuracy). These methods rely
on climbing a "cosmic distance ladder", using measurements
of nearby distances to then deduce estimates on distances slightly
further away; we shall discuss several of the rungs in this ladder
in this talk.
