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How Science Figured Out the Age of the Earth

27 points by Libertatea 13y ago

xefer 13y ago
For anyone looking for a bit more detail I would highly recommend: "Ancient Earth, Ancient Skies"[1] by G. Brent Dalrymple which is a distillation of the author’s earlier, more scholarly work: "The Age of the Earth"[2] if you're looking for a lot more detail. [1] http://amazon.com/o/asin/0804749337 http://amazon.com/o/asin/0804749337 [2] http://amazon.com/o/asin/0804723311 http://amazon.com/o/asin/0804723311
hdivider 13y ago
A really good book on this is The Dating Game: One Man's Search for the Age of the Earth http://www.amazon.com/The-Dating-Game-Search-Earth/dp/0521893127/ref=sr_1_2?ie=UTF8 http://www.amazon.com/The-Dating-Game-Search-Earth/dp/052189... by Cherry Lewis [0]. It's an informative read. Especially the stuff about the actual calculations. It's fun to realise how massively the early approaches (salinity, heat transfer considerations, etc.) were blown out of the water by good old nuclear decay (Rubidium->Strontium, as I recall). Once again, nuclear phenomena are damn near magical. [0]: http://www.bris.ac.uk/earthsciences/people/cherry-l-lewis/index.html http://www.bris.ac.uk/earthsciences/people/cherry-l-lewis/in... . It's a solid department (though I'm biased - I used to study there). They're totally immersed in all things earth science. Rarely seen so much enthusiasm.
hawkharris 13y ago
If you ever start to feel old, think in geologic time.
- jofer 13y ago
  As a geologist, I assure you, it doesn't help. The fact that your great-great-great grandparents are basically the same age as you (penecontemporaneous with you, to use my favorite term) isn't exactly comforting. I'm kidding, of course :) On the bright side, it's _really_ incredible how far civilization has come in such a short time! Putting that in geologic perspective just makes it even more impressive.
elyase 13y ago
This is how it works: "Rock minerals naturally contain certain elements and not others. By the process of radioactive decay of radioactive isotopes occurring in a rock, exotic elements can be introduced over time. By measuring the concentration of the stable end product of the decay, coupled with knowledge of the half life and initial concentration of the decaying element, the age of the rock can be calculated. Typical radioactive end products are argon from potassium-40 and lead from uranium and thorium decay." -- Wikipedia
- pdonis 13y ago
  This quote does leave out one crucial item, though (I don't know exactly which Wikipedia page you are quoting from, so I don't know if it's brought up elsewhere on the page, or on a page it links to): how do you know the initial concentration of the decaying element? (This is often asked by creationists trying to discredit radiometric dating techniques.) The answer is that, if you make some additional measurements, you can figure it out from the data, as explained in the Isochron Dating FAQ: http://www.talkorigins.org/faqs/isochron-dating.html http://www.talkorigins.org/faqs/isochron-dating.html
coldcode 13y ago
Science history is among my favorite topics. Today we take it for granted how much we know about things. Imagine being in a time when we knew virtually nothing and still having the imagination to figure it out.
srean 13y ago
A conundrum that would tickle my (geologist) dad no end was that some of the earlier estimates of the age of the universe were lower than some of the older rocks found on the earth. The article mentions red-shift of galaxies, it allows us to estimate their speed. One of the older scientific estimates of the age of the universe was based on "reverse" extrapolating those values.
SmokyBourbon 13y ago
Does anybody have a link to an article on the subject from a reputable publication?

27 points by Libertatea 13y ago

xefer 13y ago

For anyone looking for a bit more detail I would highly recommend: "Ancient Earth, Ancient Skies"[1] by G. Brent Dalrymple which is a distillation of the author’s earlier, more scholarly work: "The Age of the Earth"[2] if you're looking for a lot more detail. [1] http://amazon.com/o/asin/0804749337 http://amazon.com/o/asin/0804749337 [2] http://amazon.com/o/asin/0804723311 http://amazon.com/o/asin/0804723311

hdivider 13y ago

A really good book on this is The Dating Game: One Man's Search for the Age of the Earth http://www.amazon.com/The-Dating-Game-Search-Earth/dp/0521893127/ref=sr_1_2?ie=UTF8 http://www.amazon.com/The-Dating-Game-Search-Earth/dp/052189... by Cherry Lewis [0]. It's an informative read. Especially the stuff about the actual calculations. It's fun to realise how massively the early approaches (salinity, heat transfer considerations, etc.) were blown out of the water by good old nuclear decay (Rubidium->Strontium, as I recall). Once again, nuclear phenomena are damn near magical. [0]: http://www.bris.ac.uk/earthsciences/people/cherry-l-lewis/index.html http://www.bris.ac.uk/earthsciences/people/cherry-l-lewis/in... . It's a solid department (though I'm biased - I used to study there). They're totally immersed in all things earth science. Rarely seen so much enthusiasm.

hawkharris 13y ago

If you ever start to feel old, think in geologic time.

jofer 13y ago
As a geologist, I assure you, it doesn't help. The fact that your great-great-great grandparents are basically the same age as you (penecontemporaneous with you, to use my favorite term) isn't exactly comforting. I'm kidding, of course :) On the bright side, it's _really_ incredible how far civilization has come in such a short time! Putting that in geologic perspective just makes it even more impressive.

elyase 13y ago

This is how it works: "Rock minerals naturally contain certain elements and not others. By the process of radioactive decay of radioactive isotopes occurring in a rock, exotic elements can be introduced over time. By measuring the concentration of the stable end product of the decay, coupled with knowledge of the half life and initial concentration of the decaying element, the age of the rock can be calculated. Typical radioactive end products are argon from potassium-40 and lead from uranium and thorium decay." -- Wikipedia

pdonis 13y ago
This quote does leave out one crucial item, though (I don't know exactly which Wikipedia page you are quoting from, so I don't know if it's brought up elsewhere on the page, or on a page it links to): how do you know the initial concentration of the decaying element? (This is often asked by creationists trying to discredit radiometric dating techniques.) The answer is that, if you make some additional measurements, you can figure it out from the data, as explained in the Isochron Dating FAQ: http://www.talkorigins.org/faqs/isochron-dating.html http://www.talkorigins.org/faqs/isochron-dating.html

coldcode 13y ago

Science history is among my favorite topics. Today we take it for granted how much we know about things. Imagine being in a time when we knew virtually nothing and still having the imagination to figure it out.

srean 13y ago

A conundrum that would tickle my (geologist) dad no end was that some of the earlier estimates of the age of the universe were lower than some of the older rocks found on the earth. The article mentions red-shift of galaxies, it allows us to estimate their speed. One of the older scientific estimates of the age of the universe was based on "reverse" extrapolating those values.

SmokyBourbon 13y ago

Does anybody have a link to an article on the subject from a reputable publication?