

Terrence Tao: The Cosmic Distance Ladder - xtacy
http://terrytao.files.wordpress.com/2010/10/cosmic-distance-ladder.pdf

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Jun8
If you do nothing else today, go through this presentation!

I am humbled by the intellectual capacity of (i) these early
philosophers/natural scientists/physicists (they meant the same at they time)
and (ii) Tao's gift of making things "as simple as possible, but not any
simpler".

On a tangential thought: where are the Taos of chemistry, economics, or
physics (Feynman was it when he was alive, but I think Tao's explanation
powers surpass even him) and, of course, philosophy. Currently, science
popularizers seem to either give you a watered down, sweetened, "intelligent
layman" version (e.g. Hawking and Mlodinow's _The Grand Design_ ) or hard core
stuff that only practitioners can understand.

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brainproxy
A highly accessible overview of Western philosophy, from the Greeks to present
day, can be found in Frederick Copleston's 9-volume "A History of Philosophy"
series.

Vol 1, as sold on Amazon: [http://www.amazon.com/History-Philosophy-Vol-Pre-
Socratics-P...](http://www.amazon.com/History-Philosophy-Vol-Pre-Socratics-
Plotinus/dp/0385468431/)

A sharp person with a high school education, and a willingness to lookup terms
or references s/he doesn't understand (with the help of Google, Wikipedia,
etc.), would be able to readily digest these books, though even postdocs would
find much in them that is challenging and intriguing.

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brainproxy
This fact surprises many, but Hubble was actually quite critical of using red-
shift as an indicator of cosmological distance. In 1953 (the year before his
death) he even convinced Robert Millikan, 1923 recipient of the Nobel Prize
for Physics and director of physics at the California Insitute of Technology,
that it was probably wrong to interpret red-shift as an expanison of the
universe.

Hubble ended his book _Observational Approach to Cosmology_ with the
statement: "... if the recession factor is dropped, if red-shifts are not
primarily velocity-shifts, the picture is simple and plausible. There is no
evidence of expansion and no restriction of time-scale, no trace of spatial
curvature, and no limitation of spatial dimensions. Moreover, there is no
problem of inter-nebular material. The observable region is thoroughly
homogeneous; it is too small a sample to indicate the nature of the universe
at large. The univers might even be an expanding model, provided the rate of
expansion, which pure theory does not specify, is inappreciable. For that
matter, the universe might even be contracting."

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giu
Blog post: [http://terrytao.wordpress.com/2010/10/10/the-cosmic-
distance...](http://terrytao.wordpress.com/2010/10/10/the-cosmic-distance-
ladder-ver-4-1/)

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dmfdmf
"By establishing the relationship of feet to miles, he can grasp and know any
distance on earth; by establishing the relationship of miles to light-years,
he can know the distances of galaxies." Ayn Rand "Introduction to Objectivist
Epistemology"

<http://aynrandlexicon.com/lexicon/measurement.html>

