In a letter to Physics Today
that the terms "Stone Age," "Iron Age," etc. refer
to the material used most commonly to construct knives.
This means we are currently in the Stainless Steel Age,
possibly changing to the Plastic Age.
By some reasonable measure, when would the transition happen?
2009-05-28 Thursday 17:37:37
Many people have jaws too small to contain thirty-two teeth,
and have to have their "wisdom teeth" extracted.
When did this practice become widespread?
And how common is it to have an
2009-02-24 Tuesday 12:41:14
A black hole at the end of its Hawking evaporation radiates
with some very large power. But the high-power period
doesn't last very long, since the mass is so small.
Apparently the overall luminosity is small enough
that it'd be hard to see a radiating black hole outside
the solar system.
What limit can you set on the density of
very small black holes
knowing only that, say, there are none in the room right now?
2009-02-04 Wednesday 22:19:29
There's a theorem in control theory that sets limits on how quickly
the gain of a feedback system can change with frequency without
driving oscillations. This is the logic behind using the
integral and/or the derivative
of the feedback signal in
mechanized control systems. One factor in the current financial
tension between short-term and long-term risk
a problem that
also appears in smaller-scale "markets."
Suppose this tension were reduced by, say, paying fund managers
investments less liquid than cash, in some quantifiable way.
Are cash commissions guaranteed to have boom and bust oscillations?
Do oscillation-free commission schemes exist?
2008-12-31 Wednesday 10:03:07
Among the different Nobel prizes, there is a big spread between
when work is done and when it is rewarded. The physics prizes seem
to go to people whose work decades ago has shaped research since,
while the peace prizes seem to go to people who are actively doing
notable things right now. What's the distribution of times
between doing something noteworthy and winning a prize for it? What
about less famous prizes?
2008-10-08 Wednesday 10:54:38
Fresh Air interviewed
Katharine Jefferts Schori
, the primate of the US Episcopal
Church, who has a doctorate in oceanography. Are advanced degrees
in the sciences more common, or less common, in the clergy than in
other nontechnical fields? How does the frequency change across
2008-10-08 Wednesday 10:27:03
If Hawking's connection between black holes and thermodynamics
is right, astrophysical black holes --- for which general
relativity predicts everything bizarre happens well inside the
horizon, and for which there are observational evidence --- are at
the zero-temperature limit. What's the "warmest"
black hole for which there is observational evidence? What's
the transition "temperature" where quantum gravity starts
2008-10-06 Monday 19:45:48
by Consumer Reports
, that breakfast cereals marketed to
children aren't terribly nutritious, has gotten some
evening-news press. The main contribution of the Consumer Reports
release seems to be that they bought a bunch of cereal and read the
nutrition labels. What's new here? Has the composition of
existing products been tweaked? Have some sweeter brands been
introduced to replace healthier ones? How do these sorts of news
blobs correlate with sales, or with marketing spending?
2008-10-06 Monday 12:29:26
What's the pressure inside an unopened soda bottle (or can)?
What's the rate at which CO2
comes out of solution
at ambient pressure? How much does the bubbling change the
temperature of the liquid?
2008-09-23 Tuesday 19:19:09
I have heard it repeated a few times now that, in some counting,
the human body is "mostly" bacteria. Is this number of
cells? biomass? genetic information? Wikipedia cites
"mini-review" in Anaerobe
. How much of the
human body and its function are bacterial in other interesting
2008-09-22 Monday 10:40:07