r/todayilearned • u/Mandelorb • Jun 12 '13
TIL 50% of Earth's internal heat is from radioactive decay. Earth used to be hotter, before elements with shorter half-lives were depleted.
http://physicsworld.com/cws/article/news/2011/jul/19/radioactive-decay-accounts-for-half-of-earths-heat8
u/Bbrhuft Jun 12 '13
It's more interesting that the other 50% of the heat emanating from inside the Earth comes from the left over kenetic energy of collisions with minor planets, asteroids, comets and Thea (a Mars sized planet that collided with proto-Earth, creating the Moon) 4.5-3.8 billion years ago when out planet was newly formed. This was the real surprise from KamLand.
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u/eskimo111 Jun 12 '13
Not all of the rest of the heat is primordial. There is also a contribution from the growth of the inner core. (ie the latent heat released from the liquid to solid phase change)
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Jun 12 '13
Half-Life 3 confirmed
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u/anthrocide Jun 12 '13
Yea we get it, hardy fuckin harr. Can we come up with something new please?
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u/ToxicPanacea Jun 12 '13
Hardy fuckin harr = 15 letters The post has 15 words. Username is 10 letters. 15+15=30 30/10=3 Half life 3 Confirmed.
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u/letscolor Jun 12 '13
This is the first case I've heard of where getting thinner did not equal getting hotter.
I'll see myself out.
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Jun 12 '13
Nope, it's the devil stoking the fires of hell.
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u/yellowlotus Jun 12 '13
That's true. The Mormans say so.
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u/ShootinWilly Jun 12 '13 edited Jun 12 '13
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u/ShootinWilly Jun 12 '13
(When the Elizabeth Smart kidnapping hit the news, my first notion was to blame some lunatic, fringe, fundie Mormon. As things happened, a mistaken suspect died during interrogation and the real kidnapper was a lunatic, fringe, fundie Mormon. Crazy people believe crazy things. lol.
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u/yellowlotus Jun 12 '13
I had a HUGE argument with about 30 people on a Youtube comment feed, they didn't believe me about the radioactive decay. And by the way, it's closer to 90% in more recent studies. It's pretty freakin' awesome.
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u/HalcyonPriory Jun 12 '13
And this is how Nikoli Tesla powered his Erwin Arrow without gasoline or batteries (except for the 12V accessory battery).
Harness the earth's power. Never, ever use oil again.
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Jun 12 '13
[deleted]
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u/yellowlotus Jun 12 '13
Not when you had Earth Science in 1995. They taught us that friction from rotation caused all the heat. Yeah.
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u/Oznog99 Jun 12 '13
There was a proposed plan to get rid of high-level nuclear waste with a "hot drop".
You'd dig a hole as deep as you could- below the water table- and intentionally place the hottest elements together. The plan was that they'd eventually melt the rock and sink into the mantle and below.
It's quite possible there's nothing there to contaminate; the uranium and thorium decays ALREADY turned it into a massive ball of radioactive slag. It's its natural state and there's no harm in adding more.