Slashdot Mirror
Solar Sailing and Physics
Roland Piquepaille writes "In this article, the New Scientist writes that the next generation of spacecraft might be propelled with the help of the sun. "Both NASA and the European Space Agency are developing solar sails and, although never tested, the concept is quite simple. A solar sail is essentially a giant mirror that reflects photons of sunlight back in the direction they came from." But Thomas Gold from Cornell University in New York says the proponents of solar sailing have forgotten about thermodynamics, the branch of physics governing heat transfer." And this is where it's becoming interesting. Gold's paper, "The solar sail and the mirror," states that "either Carnot's accepted rule is in error, or the solar sail proposal will not work at all." So, as this illustration from New Scientist shows, the real question is: "Can it really sail away?" We'll know it in September when the first tests are done. In the mean time, read this summary for more details and read the original stories for far more information."
The Solar Sail and the Mirror says:
"If this was a perfect mirror, the two temperatures will be the same"
This ignores the frequency shift due to the moving mirror. Proof falls down. Thermodynamics and conservation of momentum both still hold.
Physics correct! News at 10!
Yawn.
NO ID: BEING FREE MEANS NOT HAVING TO PROVE IT
the second law of thermodynamics is only a statistical law
I'm not a physicist, but I thought the first two laws of thermodynamics were:
1. You do not talk about thermodynamics.
2. You do not talk about thermodynamics.
Maybe I'm getting confused with something else.
Suck figs.
>We still need someting like Prometheus in order get around and about in places where the sun doesn't shine brightly.
OUCH...my doctor usually just uses an index finger!
Just another day in Paradise