Here's a short article that describes why radiometric dating is not always a sure fired thing.
Sigh. The usual strawmen.
1.
Each system has to be a closed system; that is, nothing can contaminate any of the parents or the daughter products while they are going through their decay process
Yes, and environmental weathering can and has been detected in rocks. The most amazing thing is that radiometric dating has been carried out on
meteorites, all of which yield a date of about 4.5 billion years for the Solar System. What could contaminate a meteorite in the depths of space, and how could all those meteorites all be contaminated to exactly the same extent to yield exactly the same date?
2.
Each system must initially have contained none of its daughter products.
Isochron dating explicitly assumes that initial daughter products are present in some indeterminate amount.
3.
The process rate must always have been the same. The decay rate must never have changed.
And observations of supernovae spectra from decaying elements that decayed long in the past demonstrate that their rates have not changed.
it is a known fact among scientists that such changes in decay rates can and do occur. Laboratory testing has established that such resetting of specimen clocks does happen.
Yes, you can change decay rates of certain elements in the lab. I have friends just a year older than me who've done it. They took beryllium-7, cooled it to a few kelvins, and found that the rate dropped by a few percent points. There are three obvious difficulties for the creationist:
- beryllium-7 isn't used for dating,
- most rocks don't maintain temperatures of a few kelvins,
- and changes of a few percent aren't going to change a million years into a thousand years.
Furthermore, many different elements often agree to one same date for the same rock, yet they decay via fundamentally different processes so that if one speeds up, the other should slow down. For multiple dates to agree shows that rate change can't account for the data.
4.
One researcher, *John Joly of Trinity College, Dublin, spent years studying pleochroic halos emitted by radioactive substances. In his research he found evidence that the long half-life minerals have varied in their decay rate in the past!
Note the date given as 1931; one wonders why the creationists cannot find any later quotations? I can't track down the direct quote and see if it is out of context, but another quote from John Joly quite clearly shows the implications of his own science:
Modern Science has along with the theory that the Earth dated its beginning with the advent of man, swept utterly away this beautiful imagining. We can, indeed, find no beginning of the world. We trace back events and come to barriers which close our vistabarriers which, for all we know, may for ever close it. They stand like the gates of ivory and of horn; portals from which only dreams proceed; and Science cannot as yet say of this or that dream if it proceeds from the gate of horn or from that of ivory.
In short, of the Earth's origin we have no certain knowledge; nor can we assign any date to it. Possibly its formation was an event so gradual that the beginning was spread over immense periods. We can only trace the history back to certain events which may with considerable certainty be regarded as ushering in our geological era.
John Joly is no help for creationists!
5.
If any change occurred in past ages in the blanket of atmosphere surrounding our planet, this would greatly affect the clocks in radioactive minerals.
6.
Any change in the Van Allen belt would powerfully affect the transformation time of radioactive minerals.
Bunkum and a good demonstration of how little science this site has. It
is true that the above factors would affect
C-14 dating, since C-14 dating relies on knowledge about the continuous production of C-14 in the atmosphere that is precisely dependent on such factors. However, radiometric dating of rocks on geological timescales doesn't depend on continual creation of parent isotopes, and thus this "flaw" (which is accounted for in C-14 dating using historical calibrations) doesn't apply at all.
7.
A basic assumption of all radioactive dating methods is that the clock had to start at the beginning; that is, no daughter products were present, only those elements at the top of the radioactive chain were in existence.
Again, isochron dating assumes that an indeterminate amount of daughter product is initially present. For a rock to possess multiple concordant isochron dates (as many do) would require not only that the rock simply had "some" daughter product initially present - it would require that God had carefully crafted that rock to have just the right isotopic ratios for multiple elements, none of which are necessary for life (and many of which are indeed detrimental for life - it would be far better, for example, for rocks to not contain radioactive elements at all).
There, a thorough debunking. Back to the main show ...