Precision and accuracy in glacial geology

Official definitions Old age comprises “the later part of life; the period of life after youth and middle age. Most developed-world countries have accepted the chronological age of 50 years as a definition of ‘elderly’ or older person. At the same time, the WHO recognized that the developing world often defines old age, not by years, but by new roles, loss of previous roles, or inability to make active contributions to society.

Being 60—65 years old is usually a requirement for becoming eligible for senior social programs. In developed countries, most people in their 60s and early 70s are still fit, active, and able to care for themselves.

A common rule of thumb, at least on the internet, is that it’s okay to be interested in someone “half your age plus seven” years. According to this rule, it would not be creepy for a 30 year old to date a 22 year-old, but an 18 year-old would be off-limits.

Can science prove the age of the earth? No scientific method can prove the age of the earth and the universe, and that includes the ones we have listed here. Further, it has to be assumed that the clock was never disturbed. There is no independent natural clock against which those assumptions can be tested. For example, the amount of cratering on the moon, based on currently observed cratering rates, would suggest that the moon is quite old.

However, to draw this conclusion we have to assume that the rate of cratering has been the same in the past as it is now. And there are now good reasons for thinking that it might have been quite intense in the past, in which case the craters do not indicate an old age at all see below. No scientific method can prove the age of the earth or the universe, and that includes the ones we have listed here.

Ages of millions of years are all calculated by assuming the rates of change of processes in the past were the same as we observe today—called the principle of uniformitarianism. If the age calculated from such assumptions disagrees with what they think the age should be, they conclude that their assumptions did not apply in this case, and adjust them accordingly. If the calculated result gives an acceptable age, the investigators publish it.

Examples of young ages listed here are also obtained by applying the same principle of uniformitarianism.