Jesus Tap-Dancin' Christ

I heard this argument today, that the rate at which the earth cools, even with the added heat from gravitational attraction and radioactive decay, etc. it would have been over 100 degrees C 2 million years ago. Does anyone here have info regarding that?

ps418

First, what is the rate at which the earth is cooling? What is meant by "the earth"?

Jesus Tap-Dancin' Christ

I wasn't told the rate--but it is related to the temperature difference between the earth and outer space.

And the earth is meant by the amount of geothermal energy present.

Dr.GH

This was an argument that was posed in the 1800s by Lord Kelvin. This was made disregarding two important heat sources, natural radioactivity, and gravitational friction heating. Nor were the 19th century proponents of the idea aware that the sun has a variable output.

G. Brent Dalrymple, in The Age of the Earth (Stanford: Stanford University Press, 1991) gives a good summary.

JonF

I haven't seen that exact one. It sounds like a confused version of the Kelvin calculation.

As already pointed out, Lord Kelvin estimated the age of the Earth based on cooling without including radioactive decay (about which he didn't know). He estimated an age of 20 to 400 million years ... which most geologists rejected as too little time to form the observed features.

When radioactivity was discovered, it allowed for a much older Earth with the observed temperature characteristics.

AFAIK, nobody has tried to actually back-calculate the temperature of the Earth 2 million years ago including radioactivity.

See Dalrymple, "The Age of the Earth" or see <a href="http://epswww.unm.edu/facstaff/zsharp/103/Lecture%2010,%20Age%20of%20Earth.pdf" target="_blank">http://epswww.unm.edu/facstaff/zsharp/103/Lecture%2010,%20Age%20of%20Earth.pdf</a>

[ December 11, 2002: Message edited by: JonF ]

{edited to fix link - sci}

[ December 11, 2002: Message edited by: scigirl ]</p>

Tim Thompson

The current rate of cooling of the Earth, expressed as heat energy flowing out from the surface, averages out to about 0.0615 +/- 0.0034 Watts per square meter (Physics of the Earth, F.D. Stacey, 2nd edition, Wiley, 1977; may be a tad old, but the number won't change much). Compare that to the solar constant (solar energy deposited above the atmosphere) of about 1366.5 Watts per square meter (but <a href="http://www.pmodwrc.ch/solar_const/solar_const.html" target="_blank">variable seasonally</a>).

I have no idea where the anonymous creationist came up with their argument. Without a detailed statement of why the creationist thinks there is some problem with the cooling of the Earth, I suggest you assume that the creationist argument is, as usual, <a href="http://whatis.techtarget.com/definition/0,,sid9_gci748437,00.html" target="_blank">FUBAR</a>.

Nickle

It's always a good idea to ask for references when a creationist throws out tripe like that. Why take the time to refute it when they are going off hearsay anyway.