Ah, you intend to keep them photons. I had been imagining converting to electrons and running down cabling attached to the elevator cable. The other approach might very well be better, but doesn't really require a space elevator does it?
I'd imagine they'd go with super-conducting cables personally. Space is extremely cold, so achieving a super-conducting state is simply a matter of shielding the cable from the sun. Shouldn't be too difficult... At least, not in comparison to building a space elevator in the first place!
> Space is extremely cold, so achieving a super-conducting state is simply a matter of shielding the cable from the sun.
Not quite so simple. If we're talking about a cable near the earth, where the sun sometimes shines, there are always two heat paths -- from the sun to the cable, and from the cable to deep space. It's not easy, nor is a way self-evident, to make the cable fall to deep space temperatures at a reasonable cost, given that the sun is providing heat energy that must be diverted.
> Space is cold, but getting rid of heat is not easy in a vacuum.
On the contrary, getting rid of heat in a vacuum is easier than getting rid of heat in an atmosphere. Here's a diagram of human heat loss at the surface:
According to this source, at the surface of earth, under the atmosphere, a person loses:
Perspiration: 17 watts
Conduction: 11 watts
Radiation: 133 watts
Without an atmosphere, the direct radiation of heat energy into space becomes more efficient (no greenhouse effect), and it's always the most efficient way to radiate heat.
It is the efficiency of direct radiation of heat energy that explains why objects at the surface can fall below air temperature overnight under a clear sky, as they surely do.
I think some of the confusion arises because of vacuum thermos bottles, which are really efficient at holding onto their heat. But how they work is a bit complicated. They deal with conduction and convection losses by having the vacuum barrier between the contents and the outside. As to radiation, they rely on a reflector that's part of the vacuum bottle, which has the effect of greatly slowing the rate of heat loss by radiation.
So the vacuum thermos avoids radiation heat loss, not because of the vacuum, but with a reflector. That works in space too -- many orbiting telescopes use reflectors to keep the sun's heat energy from heating up the sensors and spoiling their performance.
But a vacuum is a pretty good medium for heat loss by radiation. The moon's surface, heated to several hundred degrees Celsius during the lunar daytime, drops to 26 Kelvins after a few (earth) days of darkness (26 degrees above absolute zero). That's a new figure, lower than had been realized, and seven degrees colder than the surface of Pluto.
Interesting speculation. I can't say whether it was related in my case - certainly it wasn't first-order (discussions I am very vaguely recalling revolved around satellites, but it was at least a decade and a half ago), but it could easily have been a cause of the meme in the first place.
I do recall someone explicitly stating that radiation is a poor means of losing heat compared to convection and conduction - which seems to just be wrong.
> I do recall someone explicitly stating that radiation is a poor means of losing heat compared to convection and conduction - which seems to just be wrong.
Yes -- it's a common belief, and it's wrong. Under clear skies after dark, objects on the surface that are convectively coupled to the atmosphere will quickly fall below air temperature because of radiation heat loss, which can produce what is called "radiation fog", so named because it's caused by the air being cooled by the ground, which in turn has been cooled by direct radiation into space.
