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→Zircon Dating
:::::: On October 21, 1983 the meter was defined as the distance light travels in a vacuum in 1/299,792,458 of a second.[http://physics.nist.gov/cuu/Units/meter.html] --[[User:Rutm|Rutm]] 14:11, 13 May 2008 (EDT)
:::::: On October 21, 1983 the meter was defined as the distance light travels in a vacuum in 1/299,792,458 of a second.[http://physics.nist.gov/cuu/Units/meter.html] --[[User:Rutm|Rutm]] 14:11, 13 May 2008 (EDT)
::::Yes, if the speed of light were to double then the length of the foot would double. I can tell you that the speed of light had doubled since yesterday and there would be no way for you to prove me right or wrong. If you have access to an extensive library, can you please check out Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics, by W. H. Freeman, and read the sections on the theory of relativity, and pay attention to the explanition of the speed of light being the same in all frames of reference? I could explain to you how the equations would cancel each other out, and I will if you make me, but it takes a long time to enter in the equations into this wiki markup. Better yet, you should take two semesters of physics at any public university in the United States (preceded by a complete course in calculus). I already explained that everything depends on the speed of light. Can you please analyze the dimensions of the constants I gave you before? The electric and magnetic constants are just to examples. Look at it this way: suppose you're in a building and someone somehow shrinks you along with the building you are in. Well that sounds silly, so I guess I will have to break out the maths. But not tonight. I think I see why the consistancy of the speed of light scares you so much: the fact that an object that is more than 8,000 light years away is observable means that the universe must be older than 8,000 years. Unfortunately, I can't use this as an argument yet because the physics of Hubble shift are currently beyond my understanding, as are the physics of cosmic expansion. So I don't really know how the distances of very far away objects are measured. To be honest, I am not sure that these things are really that far away because I don't understand this, which refutes the common accusation that I have "faith" in science.
::::The sample taken for measurement was taken form an area of the crystal that was free of cracks. Let me make sure we're both clear on this: the total minimum age of the crystals was determined using <sup>207</sup>Pb/<sup>206</sup>Pb dating. The U/Pb dating I was talking about earlier was from another project published in ''Nature''. You're saying that because the two isotopes of the lead existed in different ratios over time, one isotope may have leached out (meaning more of one isotope left the crystal) at one time.
::::Even if the lead was somehow leaving the crystals (and there is no evidence that it is), there is no natural process which removes <sup>207</sup>Pb at a faster rate than the <sup>206</sup>Pb. Even if a lead-removing process started recently, it would still remove the two isotopes at the same rate leaving the ratio unchanged. Also, if the lead-removing process started and ended a long time ago, it would also remove the two isotopes at teh same rate leaving the ration unchanged.
--[[User:MichaelK|MichaelK]] 21:01, 15 May 2008 (EDT)