Both of the following calculations were wrong. But how they were corrected (or not) is what separates science from dogma.
First example, how science was wrong:
"In 1862, the physicist William Thomson (who later became Lord Kelvin) of Glasgow published calculations that fixed the age of the Earth at between 24 million and 400 million years.[2][3] He assumed that the Earth had been created as a completely molten ball of rock, and determined the amount of time it took for the ball to cool to its present temperature. His calculations did not account for the ongoing heat source in the form of radioactive decay, which was unknown at the time.
Geologists had trouble accepting such a short age for the Earth. Biologists could accept that the Earth might have a finite age, but even 100 million years seemed much too short to be plausible. Charles Darwin, who had studied Lyell's work, had proposed his theory of the evolution of organisms by natural selection, a process whose combination of random heritable variation and cumulative selection implies great expanses of time. Even 400 million years did not seem long enough.
In a lecture in 1869, Darwin's great advocate, Thomas H. Huxley, attacked Thomson's calculations, suggesting they appeared precise in themselves but were based on faulty assumptions. The German physicist Hermann von Helmholtz (in 1856) and the Canadian astronomer Simon Newcomb (in 1892) contributed their own calculations of 22 and 18 million years respectively to the debate: they independently calculated the amount of time it would take for the Sun to condense down to its current diameter and brightness from the nebula of gas and dust from which it was born.[3] Their values were consistent with Thomson's calculations. However, they assumed that the Sun was only glowing from the heat of its gravitational contraction. The process of solar nuclear fusion was not yet known to science.
Other scientists backed up Thomson's figures as well. Charles Darwin's son, the astronomer George H. Darwin of the University of Cambridge, proposed that the Earth and Moon had broken apart in their early days when they were both molten. He calculated the amount of time it would have taken for tidal friction to give the Earth its current 24-hour day. His value of 56 million years added additional evidence that Thomson was on the right track.[3]
In 1899 and 1900, John Joly of the University of Dublin calculated the rate at which the oceans should have accumulated salt from erosion processes, and determined that the oceans were about 80 to 100 million years old.[3]"
(quoted from wikipedia)
Second example, how drdino is wrong and refuse to correct it:
"Since solar radiation causes the formation of C-14 in the atmosphere, and normal radioactive decay takes it out, there must be a point where the formation rate and the decay rate equalizes. This is called the point of equilibrium. Let me illustrate: If you were trying to fill a barrel with water but there were holes drilled up the side of the barrel, as you filled the barrel it would begin leaking out the holes. At some point you would be putting it in and it would be leaking out at the same rate. You will not be able to fill the barrel past this point of equilibrium. In the same way the C-14 is being formed and decaying simultaneously. A freshly created earth would require about 30,000 years for the amount of C-14 in the atmosphere to reach this point of equilibrium because it would leak out as it is being filled. Tests indicate that the earth has still not reached equilibrium. There is more C-14 in the atmosphere now than there was 40 years ago. This would prove the earth is not yet 30,000 years old! This also means that plants and animals that lived in the past had less C-14 in them than do plants and animals today. Just this one fact totally upsets data obtained by C-14 dating."
(quoted from drdino)
