3 ms·
You are correct that a heat pump needs both a heat source and heat sink. However, radiation is quite effective at transmitting heat at high temperatures. Blac
by FiatLuxDave 11y ago
You are correct that a heat pump needs both a heat source and heat sink. However, radiation is quite effective at transmitting heat at high temperatures. Black-body radiators emit as the fourth power of the temperature, although real objects never emit quite as efficiently as ideal black-bodies. It works pretty well for stars, though, since radiation is how they lose the vast majority of their energy.
If the photosphere above the heat engine was opaque, then the heat engine would not work. So it makes sense to keep the heat engine near or above the top of the photosphere, without going high enough to overheat near the top of the chromosphere.
It's mainly just a fun idea. I have no plans of trying to build one in the near future. :)
* I am a physicist, but that is no protection against being wrong. ;)
- marktangotango 11y agoFYI David Brin explored this idea in the novel 'Sundiver' (1980)[1]. In the novel a laser is used to radiate heat out into space. This is the first book of the Uplift Trilogy. Incidentally, the second book, 'Startide Rising' is really great imo, and won a bunch of awards. [1] https://en.wikipedia.org/wiki/Sundiver https://en.wikipedia.org/wiki/Sundiver
- FiatLuxDave 11y agoAye, actually Sundiver is my favorite of David's books. I think his writing is better in later books, but I enjoy the audacious technical ideas and the classic 'closed room mystery' plot. I met David earlier this year at the NASA NIAC symposium, and spent a nice afternoon hanging out with him and Joe Haldeman and his wife. Very nice people! We toured the Swampworks and launch sites at KSC, and talked about practical methods for moving planets. It was a very enjoyable day.
- marktangotango 11y agoVery cool. You seem to be familiar with him and his work, so I'll ask this; I seem to recall that him and Vernor Vinge have sidelines doing 'scenario planning' for government agencies, is that something you've ever heard of? I've always wondered what that consisted of. Maybe I'm just searching for a reason to explain Vinge lack of productivety and imagined that?
- FiatLuxDave 11y agoI'm sorry. but I don't know much about that. However, you could ask them about it. Most sci-fi authors I have spoken with are very open to answering questions, as long as they are addressed in a respectful manner. I don't know about Vernor Vinge, but I know that David Brin has a website that you could email him at.