how old do you think the earth is
 

okay the general consensus is about 4 billion years. but the thing is how can we say the evidence of that is so solid when we haven't lived 4 billion years to either witness it or know what the signs of 4 billion years of aging are? disscuss away

well the way that i understand it, is that we've found radioactive material (carbon 14 for example) that has a very specific halflife, and we know that this material only gets to the state that its currently in through radioactive decay. so you just multiply backwards as to how many years 'x' material has been around for, and we figure that since this chunk of rock is ~4 billion years old, that the earth's age must be close to that as well.

but even then, there's no real proof to my understanding that any half-life remains static(the same). without speeding up or slowing down

hm, well i guess there no real proof that the sun will rise tomorrow; but we know it will because it is a constant. here is a somewhat confusing link that essentialy says that "yes, radioactive decay is constant"

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ok, thats a very confusing link, ill have to try and find a simpler explination. but i guess thats why there arn't tons of nuclear physisits, this stuff is hard.

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ok, this is much better

Carbon 14 decays too much after 50,000 years or so. Plus, Carbon 14 only applies to formally living things. There are other elements that have much much much longer half lives that can be used. Like Uranium and, i think, potassium. The trick with those is that they don't come in exact ratios (i think). the C12:C14 ratio is always the same in the atmosphere, so you have a starting point. But with Uranium, the initial ratios are unknown.

I think Potassium decays to Argon, tho. So if you start out with pure Potassium, you can measure the Potassium-Argon ratio against potassium's half-life. BUT, there is always the possibility of primordial argon contamination, which cast doubt on all those datings.

It was my understanding, tho, that the earth's age was mostly a factor of extrapolating geographical information, like sedimentary layers and all?

but, no, Anarchy, Half-lives NEVER change. you find a way to change the half life of a radio active element, and you'd get a Nobel prize for physics.

well according tothis link you're rightbecause there's nothing that can make it loose it's energy faster to speed up the decay prcess. but i'm thinking maybe energy is actually electricity, a little known fact is that humans actually run on electricity. the energy in our bodies may indeed be electricity that our bodies extract from food. so i'm think that maybe lightning could be a factor and something that could alter the decay process

Actually no, energy isn't electricity. Electricity is a form of energy, just like sound, light, heat, movement, etc. Electricity has absolutely nothing to do with the decay of elements.

I was going to say some stuff about the age of the earth, but Drooling Iguana got to it before me.

Shoot, the Jewish calendar says that the Earth is 5000 years old. I'll agree with that.

According to The Hitchhikers Guide To The Galaxy, it's foolish to ask such questions because the entire world could've hatched one second ago, and all our memories and knowledge could be a split second rationalization of all that we may assume has happened, even though the world may only have just begun in 7 minutes.

i agree, that's sort of the point i was trying to make, in the article iguana linked to for instance there are many flaws. however i don't exactly believe the earth is only 4000 years old either