Originally posted by JadeMantis
I am no *phycist, so please excuse my ignorance in these matters, but I do not quite understand this.
Why would the ages given vary by different amounts if there is some constant factor applied. For example, if we could look at 2 objects falling under the influence of gravity but the gravity is at some point increased by 3x. Would we be able to observe ...[text shortened]... d clearly I am no linguist either - spelling spelling spelling, oh well - you know what I MEANT]
Okay, to understand all this it's best to know a little more about both nuclear structure and radioactive decay.
Basically, a nucleus is comprised of two types of matter; protons, with a positive charge, and neutrons, with no charge. Since the protons all have the same positive charge, then they tend to want to fly away from each other, but are held together with neutrons by the strong nuclear force.
Now in small atoms this is fine, there is roughly an equal number of protons and neutrons in any given atoms nucleus and all is well. In larger nucleii however, the number of neutrons may be significantly higher than the number of protons. If we have too many neutrons in a nucleus, or there are simply too many protons and neutrons full stop then the nucleus will break apart. The energy that is released (by the convertion of an infinitesimally small amount of matter to energy by E=mc^2) is called radioactivity.
Now, there isn't just one form of radioactivity - there are in fact a number of different types, the main three being alpha, beta and, imaginatively enough, gamma.
Alpha emissions are where a particle comprising two protons and two neutrons are expelled from the nucleus, for example in the decay of uranium-238 to thorium-234. Energy is also released.
Beta emissions release either an electron (-ve charge) or a positron (+ve charge) from the nucleus, changing a neuton into a proton which balances the mass:charge of the nucleus making it stable. This is best characterised by the production of 14N from 14C (one of the extra neutrons in 14C is converted into a proton, giving the nucleus 7 protons which converts it into a nitrogen atom).
Gamma emissions are the emission of pure energy from a nucleus as it makes a transition from one element to another. After a beta decay, there is occassionally some extra energy in the atom, in which an electron is in an outer orbital, rather than the 'ground state'. Pure energy must be released, and this is done as a gamma ray - which is not a particle, like the others.
Because we are working at an extremely small scale the nucleus isn't affected by many of the same things that affect us, like gravity. Only the electrostatic, strong and weak nuclear forces affect the nucleus and nuclear decay. For the rate constant of nuclear decay to change would require the alteration of one of these forces. Since all nucleii are bound by the same rules, but are different masses, they all decay at their own unique rate. A change in the strong nuclear force would have to affect all radioactive elements by an exactly proportional amount in order to fool radiometric dating into yielding the same, but incorrect, date for the planet / universe, etc. This is all well and fine, except for the fact that (a) we have no evidence for any fundamental change in that laws of physics over the last 18 billion years, (b) we have alot of evidence (from spectral analysis of distant starlight (which is necessarily old)) that the decay constants have not changed over time, and (c) the universe couldn't have formed in the way it has if the strong nuclear force was altered, for two reasons. One, if the strong nuclear force was weaker then large atoms could not form, and possibly small ones too, because they'd constantly be falling apart, with the concommitant nuclear radiation that would be emitted. Two, if the strong nuclear force were stronger, nuclear reactions wouldn't occur, and the sun wouldn't function, except under greater pressure.
Fortunately for us, the rate constant hasn't changed, and we live on a planet heated by radioactive decay in the sun, and from radioactive decay in the planets core. But, to the creationists out there who'll try and say "look, proof of god" i'll remind you of this, this is not proof of god, just proof that these conditions exist.