It’s called measurement, Adam. Measurement. The only methods that are accepted into the fold are ones that have accurate measurements and that interpret them honestly. The ones that get “thrown under a bus” are the ones that do not. As they should be.
There are radiometric dating methods, known as Isochron dating, that do not need to know the starting point and that include built in tests for contamination.
and they work by taking measurements from multiple samples from the same rock formation and plotting them on a graph. The slope of the graph gives their age, and if there had been any contamination then the points would not lie on a straight line.
There are other radiometric techniques where the starting point is a direct consequence of the physical, chemical and crystallographic properties of the minerals concerned. For example, it is physically impossible to get lead into a zircon crystal by any route other than nuclear decay from uranium. Furthermore, if the sample is disrupted (for example by heating) the lead will leak out but the uranium will not, for precisely the same reason. This means that in such cases, the measured age will be a lower limit.
Your understanding is incorrect. Radiometric dating of terrestrial rocks may not give us an exact figure but it does give us a lower limit.
Radiometric dating of meteorites gives us the age of the Solar System as a whole. These give very consistent results of about 4.4 to 4.6 billion years by multiple different methods, which confirms that the meteorites concerned have not been disrupted geologically since their formation.
And once again, this has nothing whatsoever to do with evolution or “Darwinian assumptions.” Whoever told you that the theory of evolution, or Darwinism, has anything to do with it is either lying to you or doesn’t have a clue what they are talking about.
Diffusion of radon gas along tiny fractures in the crystals concerned.
Radiohalos have also been found in intrusions into fossil-bearing sedimentary rocks and in metamorphic rocks. Such rocks cannot have been original primordial rocks, even in a young earth model.
Sorry, but it’s contamination, it’s as simple as that. And no, there’s nothing whatsoever that is “evolutionist” or “Darwinist” about me saying that, nor is it any form of “rescuing device.” Contamination is a legitimate source of error and one of the most fundamental rules and principles of measurement in every area of science is that all possible sources of error must be fully and accurately accounted for. No exceptions, no excuses. By dismissing contamination as some sort of a “rescuing device,” young earthists are effectively insisting that the basic rules and principles of accurate and honest measurement do not apply to them. In other words, they are demanding a free pass to make things up and claim whatever they like, regardless of its truthfulness. The scientific term for doing such a thing is “lying.”
Possible sources of contamination in this case include memory effects in the mass spectrometer, insufficient care and attention in sample handling and preparation, or irradiation from nearby sources of uranium.
In the words immortalised by Wikipedia, [citation needed].