by Laura Conaway

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.