Scientific problems with radiometric dating
The present day atmospheric 3He/4He ratio is 1.39x10-6, and is referred to as RA.
A better interpretation would be that the high 3He/4He ratio arises from a deficiency in 4He in the upper mantle caused by low U+Th areas, and thus low rate of addition of radiogenic 4He." also referred to in the book "Radioactive and Stable Isotope Geology" by Hans-Gunter Attendorn and Robert N. Strictly speaking, however, those methods do not belong to the topic of Radiometric dating, the current title of this article. Valich , 10 September 2006 (UTC) I understand that the half-life of a radio-isotope is unaffected by temperature, pressure, etc.Therefore, in my opinion, one of three things should be done: (1) rewrite the section so as not to appear as overtly off-topic; (2) move those other techniques to their proper places and place a link in "See also" section; or (3) rename the article to reflect a more general topic such as "Dating techniques" or the like. But don't other radiological sources have an effect? the atomic fallout from a meteorite or a supernova in a nearby star system. Example some part is 20000 years old and other is 35000 years in same animal.It seems such events could trigger substantial 'non-spontaneous' decay that would cause is discontinuity in the typical half-life curve and set dates off by an order of magnitude. Shortopinions , 29 March 2007 (UTC) Living things have been dated over 2500 years old. Posted unsigned, at , on April 22, 2007 by User:220.127.116.11 (Talk) (5,028 bytes).Also the level of C-14 in the atmosphere could increase significantly in response to such events too: making a sample appear younger than it really is. The procedure is inaccurate either way, since in order to use radiometric dating you have to make an assumption about how many isotopes were in the object being dated, don't you?ex: I'm dating a T-rex, and I find - I don't know - twenty billion isotopes.In order to know how old the rex is based on that data, I'd have to assume that it had a certain number of isotopes from the start.
So if the isotopes had a half-life of fifty years, I could assume it started off with 80 billion isotopes and say it's a hundred and fifty years old. Zillakilla (talk) , 3 January 2008 (UTC) Um, yes, you're wrong.
Each type of radiometric dating uses the radioactive decay of only one isotope of one element.
These are ratios used in isotope dating of mantle plumes: "Popular with plume enthusiasts is the ratio of helium-3 to helium-4.
A higher ratio is characteristic of deep mantle origin, they argue.
Similar information can be gleaned from isotopes of the elements neodymium, strontium, lead, and hafnium.
The ratio of 3He/4He increases over time as 4He is produced by the decay of uranium and thorium.