Venoms have evolved independently in several different
vertebrate lineages: in snakes and lizards, and in
the platypus, and in one other mammal.
What are the transitional stages for venom to appear?
How would the appearance go in, say, a population of people?
2009-04-01 Wednesday 17:41:46
The Greenland and Antarctic landmasses are under a mile of ice.
Supposedly if this weight were removed the landmasses
would "rebound" out of the mantle. How high would they go?
2009-02-27 Friday 23:30:51
To an outside observer,
an object dropped onto a black hole never actually
crosses the horizon; it approaches the horizon
asymptotically and light from it becomes more and more redshifted.
Suppose I drop a room-temperature blackbody in a hole.
How long does it take before the redshifted temperature
is colder than the Hawking temperature of the horizon?
2009-02-27 Friday 23:24:26
Yesterday's solstice was the day when the northern hemisphere
gets less solar irradiance than any other. In most countries this
is "midwinter," but in the United States it's "the first
day of winter." When did this label change?
2008-12-22 Monday 06:58:50
New "open" signs at restaurants, with bright red and blue LEDs,
bring out some chromatic aberration in my glasses: viewed
peripherally, the different-colored parts don't line up.
Quantify? Why have I only just started to notice this?
2008-11-11 Tuesday 09:44:38
Passing traffic makes Doppler-shifted noises ("wheeee-oooom").
Useful trick: map between musical interval of the shift
and the speed of the traffic?
2008-11-11 Tuesday 09:38:19
Suppose I replace an incandescent light bulb with a more expensive,
more energy-efficient, longer-lived light — a CFL, an LED,
whatever — based on the expectation that it'll cost less over
its life. How old does my incandescent bulb have to be before I
actually save anything?
2008-10-28 Tuesday 21:42:08
When using χ2
minimization to estimate parameters
from some data set, what fraction of the fits stop converging in
the "wrong" place?
2008-09-28 Sunday 16:55:01
You can't interact with a physical system without disturbing
it, though you can ignore the disturbance in the limit where
ħ is small. Similarly, you can't interact with a market
for some product (by asking or buying or offering or selling)
without affecting the "market price" seen by others, but
you can neglect that change unless your exchanges comprise a large
fraction of the market. There is some correspondence here. Clearly
it'd be easy to take this correspondence as justification for
saying some really dumb things. Are there any useful insights
2008-09-26 Friday 14:50:23
Parity nonconservation in weak interactions can interfere with
strong or electromagnetic interactions to produce parity-forbidden
transitions or correlations. Without some unusual enhancement, the
approximate statement "strong and electromagnetic interactions
do not have pseudoscalar observables" is accurate to
. What similar statement can one make about CPT
2008-09-21 Sunday 14:21:05