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avramI finished Urth of the New Sun this evening; a bit of a slog. The first four books remain brilliant even on the third reading, but the fifth just isn’t as good.
Now I’m reading a galley of Cory Doctorow’s upcoming novel, Eastern Standard Tribe. It’s fun so far, but one thing has me puzzled. Cory’s invented coffium, coffee made with heavy water that doesn’t cool off. Assuming that’s an exaggeration (even stars cool down eventually), does this idea work scientifically? Does heated heavy water take a dramatically longer time to cool than light water does?
I’ve tried using Google to find out what the specific heat of heavy water (D2O) is, without luck. This suggests to me that it’s the same as the specific heat of H2O (1.00 cal/g °C). Anyone out there know any different?
Heavy water is about 10% denser than regular water, which would slow its cooling a bit since you’ve got more mass trying to shed heat through the same surface area; I assume you’d get a 10% increase in cooling time, but I haven’t bothered to look up the actual formula and run the numbers. That’s not enough of a change to justify the claim Cory’s narrator is making.
It also has slightly higher boiling (101.42° C) and freezing (3.81° C) points than regular water does, and it’s about 10% denser; I don’t know what that would do for cooling, if anything.
Now I’m reading a galley of Cory Doctorow’s upcoming novel, Eastern Standard Tribe. It’s fun so far, but one thing has me puzzled. Cory’s invented coffium, coffee made with heavy water that doesn’t cool off. Assuming that’s an exaggeration (even stars cool down eventually), does this idea work scientifically? Does heated heavy water take a dramatically longer time to cool than light water does?
I’ve tried using Google to find out what the specific heat of heavy water (D2O) is, without luck. This suggests to me that it’s the same as the specific heat of H2O (1.00 cal/g °C). Anyone out there know any different?
Heavy water is about 10% denser than regular water, which would slow its cooling a bit since you’ve got more mass trying to shed heat through the same surface area; I assume you’d get a 10% increase in cooling time, but I haven’t bothered to look up the actual formula and run the numbers. That’s not enough of a change to justify the claim Cory’s narrator is making.
It also has slightly higher boiling (101.42° C) and freezing (3.81° C) points than regular water does, and it’s about 10% denser; I don’t know what that would do for cooling, if anything.
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(no subject)
Date: 2003-12-24 11:48 pm (UTC)http://www.slwater.com/slwEnglish/seizouE.htm
gives specific heat of light water as 4.19J/g and heavy as 4.208J/g, which is close to zip. So, no, the simple "heavy vs light" doesn't work but then a lot of SF has such in it.
Heavy water is toxic, if someone were to make coffium their major fluid intake they would likely become ill as the concentration of D2O and DHO in their body went up. However, a cup or two isn't going to hurt them.
(no subject)
Date: 2003-12-25 06:25 pm (UTC)But I am very, very glad that the fifth book exists for idiots like me.