5,286 reputation
1329
bio website keith-s-thompson.github.com
location San Diego, CA
age 55
visits member for 2 years, 10 months
seen Aug 25 at 22:20

I'm a programmer and all-around nerd living in San Diego, California.
I work at JetHead Development Inc.

E-mail: Keith.S.Thompson@gmail.com


Nov
19
comment If neutrinos travel faster than light, how much lead time would we have over detecting supernovas?
Typos: Meanwhile, the core collapse and rebound emits energy in forms that are absorbed by the body of the star, causing it to heat up.
Nov
18
answered Why does the “Troll-Mobile” not work?
Nov
18
comment How does a mobile phone vibrate without any external force?
For those who want to Google it, it's "eccentric drive".
Nov
18
comment If neutrinos travel faster than light, how much lead time would we have over detecting supernovas?
(ran out of characters) The bulk of the star isn't significantly transparent at all. We don't see the light from the blast until most of the star is blown away -- which happens in a matter of a few minutes or hours.
Nov
18
comment If neutrinos travel faster than light, how much lead time would we have over detecting supernovas?
Is scattering really the answer? My understanding is that the core collapse is a quick event that generates a blortload of neutrinos; the neutrinos travel through the material of the star (and anything else in their path) and reach us without delay. Meanwhile, the core collapse and rebound emits energy in forms that's absorbed by the body of the star, causing it to head up. We don't see the visible light until that energy (1) reaches the surface of the star, causing it to glow more brightly, and/or (2) blows away most of the star's mass, exposing the bright core.
Nov
18
awarded  Nice Answer
Nov
18
answered How does a mobile phone vibrate without any external force?
Nov
18
comment Can a photon passing by an open space barycenter of a system of masses be modeled as if all the system's mass is at the barycenter?
Actually, the barycenter of the Sun-Jupiter system is above the Sun's surface, at 1.068 solar radii from the Sun's center, according to Wikipedia. (It might dip below the surface when Jupiter and Saturn are at opposition; I haven't crunched the numbers.)
Nov
18
comment Can a photon passing by an open space barycenter of a system of masses be modeled as if all the system's mass is at the barycenter?
@user1003469: The Earth is a special case. Any spherically uniform body is gravitationally equivalent, for any object outside the surface of the sphere, to a point source at the sphere's center.
Nov
16
comment Best time of the year to see the star Alpha Centauri in Chile, Santiago
Two hours later than midnight is 2AM, yes? Or am I missing something?
Nov
14
comment What makes matter “solid”?
The idea that glass is really a liquid is controversial.
Nov
13
awarded  Autobiographer
Nov
12
comment Why is this radio telescope's reflector spherical and not parabolic?
A paraboloid would probably be better if the telescope were aimed only in one direction, straight up. Most radio telescopes steer by moving the entire dish until the axis and receiver are aligned directly with the target. But Arecibo's dish is immovable, and to aim at targets off the vertical, only the receiver is moved. A spherical shape gives uniform reception over the entire range to which it can point. (A 1000-foot steerable dish would probably be a paraboloid.)
Nov
9
comment Difference between baryonic, inertial and gravitational mass? (and relation to dark matter)
@FlorinAndrei: Isn't that pretty much what "matter" means?
Nov
3
comment 2012: Is there some astronomical event happening?
And I just posted a small correction (not relevant to the current point) on your blog post.
Nov
2
answered Does the rotation of the earth dramatically affect airplane flight time?
Nov
2
awarded  Excavator
Nov
2
revised Age of the Earth and the star that preceded the Sun
Fix typo,capitalize Sun and Earth
Nov
2
suggested suggested edit on Age of the Earth and the star that preceded the Sun
Oct
31
comment Does the rotation of the earth dramatically affect airplane flight time?
During the flight, you need to get up to use the restroom. There's one 10 rows in front of you, and another 10 rows behind you. Does it take longer to walk to the one that's moving away from you at 600 mph than the one that's moving towards you at 600 mph?