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Author of Beta's Rule: "Never add to code that doesn't work."


Sep
24
awarded  Autobiographer
Sep
7
comment How can interstellar space have a temperature of 2-3K?
If you think of temperature as being about the motion of molecules, then it's about the average of their kinetic energy, not the sum. A pot of boiling water (at sea level, in normal weather) is at 100C, no matter how big it is.
Sep
7
comment How do you find the average speed and average velocity?
Which of these do you understand: "speed", "velocity", "average"?
Sep
6
comment Can resistance be directional?
Imagine a thick bundle of insulated copper wires, all running in the same direction.
Jun
30
comment Why does the speed of the propellant limit the speed of a space ship in open space?
@this: The same can be said of a rocket employing baking soda and vinegar, if the fuel tanks are big enough.
Jun
30
awarded  Supporter
Jun
17
comment Hydrostatic pressure - doesn't density vary with depth?
It's interesting to note that if the Pacific were ten times deeper, there might be ice at the bottom...
Jun
17
comment Do black holes cause gravitational redshift?
The edited question is clearer, but you still seem to be confusing two different questions, 1) will the ray escape? (No, it won't), and 2) will it be red-shifted? (Yes, for some observers.)
Jun
17
comment Do black holes cause gravitational redshift?
Is the source inside the event horizon, or outside? (There is now some doubt about whether event horizons actually exist, but bear with me.)
Jun
11
comment Moon's pull causes tides on far side of Earth: why?
When I take a little boy by the hands, pick him up and twirls around, his arms are pulled horizontal; that is understandable, since I am pulling them. But his legs are pulled horizontal too, even though no one is pulling them. Likewise, he pulls my arms outward from my body, but somehow my coattails are also pulled outward from my back.
Jun
9
comment Why is electric current dangerous to humans?
Few cells can survive the trip up to the boiling point, never mind the effect of the boiling.
May
12
answered Electric Field due to a disk of charge. (Problem in derivation)
Apr
10
comment Why isn't jumping from a high altitude fatal?
@Luaan: No, I would not call hitting a stone wall "friction", and I don't see how you got there. I think that "friction" is a useful term for solid-solid interaction, but it should not be extended to solid-gas interaction unless we remember that we are talking about an entirely different mechanism. I hear it used to refer to the entire process of heat generation in reentry, so the division of heat generation into "compression" and "friction" seems misleading at best.
Apr
9
comment Why isn't jumping from a high altitude fatal?
@EricLippert: I suspect that this is a "tomayto"/"tomahto" distinction. What is air "friction" if not imparting momentum to air molecules? And it's hard to do that without compressing the air.
Apr
2
comment limited number of photons problem
What's the difference between disappear (i.e. I know it's right there on the table, but I can't see it) and be invisible (i.e. when I look at the moon, I know that I'm looking at some human footprints, but I can't make them out)?
Apr
2
comment Can a magnet or a magnetic field push gravity?
What does "push gravity" mean?
Feb
23
comment Why is the moment of inertia for a hollow sphere higher than a uniform sphere?
A simpler question: why does a ring have a higher moment of inertia than a disk?
Feb
17
awarded  Commentator
Feb
17
comment Does space curvature automatically imply extra dimensions?
Zogg from Betelgeuse made a very helpful video on the subject. I cannot recommend it strongly enough.
Dec
29
comment Is it possible to “cook” pasta at room temperature with low enough pressure?
Oh, you'd be surprised.