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bio website david.carybros.com
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Jan
7
comment What properties do you need for building a tower?
@AlanSE: I am also mystified by the "1 km thickness". All the references listed at the Wikipedia: space elevator article that I've seen so far seem to assume ribbon of 1 meter wide or less.
Jan
7
comment What properties do you need for building a tower?
Yes, your calculation shows that the free breaking length of a constant-cross-section carbon nanotube rope in constant 1g gravity is not quite long enough to reach from geostationary orbit all the way to the surface. However, all modern space elevator designs do not have constant 1g gravity, and are not constant-cross-section -- they are tapered.
Jan
6
comment What properties do you need for building a tower?
How are "coal mines" relevant? My understanding is that most carbon nanotubes are produced from ethylene or methane, in turn purified from natural gas. The amount of carbon in a single year's production of ethylene -- 109 million tonnes in 2006 -- is over 4 orders of magnitude more than the 1,500 ton space elevator mentioned in the Space Elevator FAQ, which in turn is about 3 times the 400 ton weight of the international space station.
Jan
1
answered Why is an air conditioner more efficient in a low-thermal-mass house?
Dec
26
comment Why is an air conditioner more efficient in a low-thermal-mass house?
In principle, that would be relevant if I ever wanted to "reduce the temperature (of the room) by an appreciable amount". However, in practice, every thermostat I've ever seen attempts to keep the temperature (of the room) the same. Or is there some connection between the temperature of the outside air (that the air conditioner cools off and blows into the room) and the thermal mass that I am missing?
Dec
26
awarded  Critic
Dec
26
asked Why is an air conditioner more efficient in a low-thermal-mass house?
Oct
22
comment Would it be possible for geophysicists/geoengineers to develop an artificial way of trapping carbon in the ocean?
@annav: Huh? I thought that fish eat plankton. Wouldn't more plankton lead to more or bigger fish (or both)?
Oct
8
answered Can 2 beams of ultraviolet light intersect and be visible where they intersect?
Oct
2
answered What is the force exerted on a body that doesn't move?
Aug
12
comment Graphene space elevator possible?
@AlanSE: To answer your question, space-based solar power uses a "transmission line from GEO to Earth" with a linear density of zero.
Aug
9
awarded  Student
Aug
9
asked How do aerospace engineers choose a landing system? (Curiosity rover)
Jun
1
revised How much energy is in a lightning strike?
add direct links to the Wikipedia articles alluded to
Jun
1
comment How much energy is in a lightning strike?
related: Can energy be extracted from clouds?.
Jun
1
suggested suggested edit on How much energy is in a lightning strike?
Dec
25
awarded  Yearling
Nov
13
awarded  Organizer
Nov
13
revised Is a given volume of sparkling water lighter or heavier than the same volume of still water?
add tags, etc.
Nov
13
suggested suggested edit on Is a given volume of sparkling water lighter or heavier than the same volume of still water?