Why 24 hours in a day?

It appears that the Egyptians were responsible for the 24 hour day. The Eqyptians were fond of counting in base twelve (instead of base 10 which is commonly used today). This is thought to be because they counted finger joints instead of fingers. Each of your fingers has three joints, so if you count by pointing to finger joints with your thumb you can count to twelve on each hand. This might seem arbitrary, but is actually just a strange as counting in base ten simply because we have ten digits.

Another reason the Egyptians (and Indians) liked counting in base 12 is that 12 has a larger number of integer factors than 10. ie. 12/6=2, 12/4=3, 12/3=4, 12/2=6, while 10/5=2 and 10/2=5 are all there are for the number 10.

The Egyptians divided the clock into 12 hours of daytime and 12 hours of night-time (or alternatively 10 hours between sunrise and sunset, an hour for each twilight period and 12 hours of darkness). This is known because of various sundials from the period which have been found to be marked with hours. Interestingly this means that hours started out changing in length with the seasons (as the amount of daylight vs. darkness changes).

There is a more in-depth explanation for the division of night-time into 12 hours which is based on the number of "decan" stars which were seen to rise during summer nights in Ancient Egypt. A "decan" star was a star which rose just before sunrise at the beginning of a 10-day "decade" in Ancient Egypt. 36 "decan" stars marked the passage of a year for the Egyptians (or 36 10 day periods). During summer nights, 12 decan stars rose - one for each "hour".

However, hours did not have a fixed length until the Greeks decided they needed such a system for theoretical calculations. Hipparchus proposed dividing the day equally into 24 hours which came to be known as equinoctial hours (because they are based on 12 hours of daylight and 12 hours of darkness on the days of the Equinoxes). Ordinary people continued to use the seasonally varying hours for a long time. Only with the advent of mechanical clocks in Europe in the 14th Century, did the system we use today become common place.

I'm not someone who believes that each day was 24-hours long, but I think it's debatable whether Paul was trying to claim that God's rest was equal to the seventh day. He could have meant that, or he could have just being using it as an illustration. Having said that, we know that both Adam and Eve were both made on the sixth day. Yet we also know that there was time on the sixth day for Adam to be made, to 'be settled' in the Garden of Eden, to name all the different kinds of animals, to start to notice that all the animals had mates and he didn't (and you need to observe most animals for quite a while to learn to distinguish their sex, and apparently he observed them for a while to choose their names as well), and then for him to be go into 'a deep sleep' (not a 10-minute nap) and Eve to be created. Now while I agree with what young-earth-creationists say that it is theoretically possible for God to do all that stuff in however short a time he wanted, Adam was a mere man - I don't think he could have done all that stuff in between his creation and Eve's in 24 hours. And indeed, I think the statement of God that 'it is not good for the man to continue by himself' implies that he had by this time 'continued by himself' for more than just a few hours. With regard to the observable universe, be wary when trusting what scientists say if it can't be tested. No scientific measurements have really been made about what the universe was like 10000 years ago or what it's like 10000 light-years from here - all we can do is look at the light that arrives here now, and assume that most conditions in the universe are the same as here - that gravity has always worked the same as it does now, that light has always travelled at the same speed it does now, etc. The predictions we come to based on that are based on a hundred sweeping assumptions about the nature of the universe, many of which rarely get questioned, because nobody will ever know if they're wrong. Which is why I don't criticise young-earth-creationists on scientific grounds. Scientists have come up with a lot of evidence to support the 4500MY age of the earth, and it might be true. But it's kind of suspicious that a much younger earth, (not necessarily 6000years, maybe just 100million years) would be crippling to the atheistic-evolution theory that they're so desperate to hold on to no matter how much evidence there is that it's impossible. If evolution required the earth to be 6000years old, do you think that's what all scientists would have proven by now? Of course they would. So don't be too dogmatic about the age of the earth - remember that most evidence on both sides of the argument is found by people who have a vested interest in proving a particular age because of their theism or atheism.

the incas and the mayas