This site is not maintained. Click here for the new website of Richard Dawkins.

← A Hot Young Earth: My Answer to the Annual Edge Question

A Hot Young Earth: My Answer to the Annual Edge Question - Comments

Cook@Tahiti's Avatar Comment 1 by Cook@Tahiti

Comment Removed by Author

Sun, 15 Jan 2012 20:18:24 UTC | #908653

crusader234's Avatar Comment 2 by crusader234

Ive always thought Ice core samples would show the earth to be older than 10 000 years , also there should be a record of the flood in there somewhere.... and there isnt...

Sun, 15 Jan 2012 22:28:13 UTC | #908686

hellosnackbar's Avatar Comment 3 by hellosnackbar

I was sent to see the headmaster of the catholic school I went to when Noah's Ark was discussed in a religipn lesson. I asked where all the water of the 40days inundation came from and where it went to afterwards and how could anybody accept such tosh. The young earth creationists and silly Mohammedans get upset when one laughs at them.

Sun, 15 Jan 2012 22:39:23 UTC | #908689

rod-the-farmer's Avatar Comment 4 by rod-the-farmer

Sorry, I must be dim. I thought his explanation of why Lord Kelvin was wrong about heat transfer quite incomplete, and not at all convincing. Am I missing something ?

Mon, 16 Jan 2012 03:00:01 UTC | #908743

KRKBAB's Avatar Comment 5 by KRKBAB

Hi Rod- perhaps this (from C.Z.s response in Discovery magazine) might make it clearer:

[CZ: It may help for me to quote a lengthy passage from the American Scientist article I cited. The authors are writing here about a scientist named John Perry realized in the late 1800s why Kelvin might be wrong--even though plate tectonics had yet to be discovered:

Perry discovered the flaw in Kelvin's argument in 1894 but, reluctant to embarrass his patron, tried first to convince Kelvin face to face and by private correspondence. He was brushed off, either because Kelvin did not understand Perry's approach or because he was not interested. In 1895, therefore, Perry decided to go public, and he wrote to the journal Nature: "I have sometimes been asked by friends interested in geology to criticize Lord Kelvin's calculation of the probable age of the earth. I have usually said that it is hopeless to expect that Lord Kelvin should have made an error in calculation." Instead of focusing on Kelvin's math, Perry suggested that one should examine his assumptions. In Kelvin's model, the thermal gradient near the surface of the Earth (or, in the thought experiment given above, of the turkey) drops as the cooled outer skin thickens with age. If the Earth were much older than about 100 million years, this skin would be so thick that the thermal gradient would be much lower than is observed. Perry realized that there is a simple way to stop the skin from thickening: He proposed that heat might be transferred much more efficiently in the interior of the Earth than at the surface. If this were so, the deep interior could provide a large store of heat, which would keep the surface temperature gradient high for a long time, and Kelvin's estimate of the age of the Earth would be too low, potentially by a large multiple. Perry had various suggestions as to how this might happen, but, for our purposes, his most important argument was that convection in the fluid, or partly fluid, interior of the Earth could transfer heat much more effectively than does diffusion. He pointed out that if only a thin outer skin of the planet is solid and if the rest of the Earth is a convecting fluid, then the interior would be well mixed and at the same temperature throughout. Perry's model thus replaces the thought-experiment turkey with a turkey-sized bottle of, say, hot cider. Only the outer few millimeters of this object are solid (the glass of the bottle), and convection churns the interior. Thus the temperature gradient at the surface can stay high for a very long time. Perry's calculation shows that if the Earth has a conducting lid of 50 kilometers' thickness, with a perfectly convecting fluid underneath, then the measured thermal gradients near the surface are consistent with any age up to 2 billion or 3 billion years. Recognizing that heat transfer in the mantle cannot be perfectly efficient, Perry subsequently modeled the deep interior as a solid with high "quasi-diffusivity," His results agreed with the original simple calculation in suggesting that the Earth could be several billions of years old. Full calculations of convection in the mantle (which were impossible until the advent of computers) confirm that Perry's reasoning was sound. In other words, Perry was able to reconcile a physical calculation of Earth's thermal evolution with the great age that geologists required. Perry needed nothing more than to introduce the idea that heat moved in the deep interior of the Earth more readily than it moved in the outermost layers. Yet to this day, most geologists believe that Kelvin's (understandable) mistake was not to have known about Earth's internal radioactivity.]

Mon, 16 Jan 2012 14:49:58 UTC | #908837

Premiseless's Avatar Comment 6 by Premiseless

I see submarine volcanic activity can now be monitored, which seem to also be worrying the military!

Tue, 17 Jan 2012 13:35:55 UTC | #909146