The Dagobah System

Corrected by an Astrophysicist. Dang.

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Bill Wolff on the pennies

Got this amazing correction from astrophysicist to the (radio stars) Summer Ash:

BTW, I know I'm a day late, so maybe someone else caught it, but I have a correction for Thursday's show. During the ramble, Bill Wolff was talking about the story with a quadrillion pennies that would reach to Saturn and he incorrectly said that they would melt. Could you inform him that space is cold, not hot? I just looked into this a bit and it appears that metals exposed to the vacuum of space actually undergo a "cold-weld" effectively bonding together without the aid of a bonding medium. This doesn't happen on Earth because the surfaces are oxidized, but in a vacuum, if the oxide films on the surfaces of the pennies were cleaned off, they would not return and the surfaces at which the pennies touched would effectively weld together. So I guess you might have a solid rod of pennies from here to Saturn, but thanks to the cold, not heat, of space.

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Is anyone else inexplicably pleased by the phrase "solid rod of pennies"?

Sent by Stewart | 11:12 AM | 1-15-2008

Umm, I do believe cold welding is due to the vacuum of space, rather than the "cold, not heat, of space". I can give literature citations if anyone is interested. Heat actually increases the force of adhesion. Further, cold welding can and does occur on Earth... if only in a laboratory setting.

Sent by Anna (A lowly chemist) | 5:52 PM | 1-15-2008

Anna, chemistry is both fascination and a weakness of mine, so I completly defer to you on that. I wrote the above in an email originally and only meant to point out the misconception that space hot. I think you are totally right about the vacuum and not the temperature being responsible for the 'cold weld'. But the vacuum of space is essentially cold because there are so few vibrating molecules with kinetic energy and at least out toward Saturn, less and less solar radiation, right? That's my understanding at least...

Sent by Summer Ash | 8:41 AM | 1-16-2008