I was looking at someone's blog last week. I came across this picture of a large floral clock with its digits in Roman numerals. And it reminded me of something my fifth or sixth grade teacher once told me; the Romans did not have a symbol for zero. As the Wikipedia post suggests, dots and blank spaces might have been utilized.
But, "Records show that the ancient Greeks seemed unsure about the status of zero as a number. They asked themselves, 'How can nothing be something?', leading to philosophical and, by the Medieval period, religious arguments about the nature and existence of zero and the vacuum." Thus, knowing the difference between, say, 16 barrels and 106 barrels was a matter of context. (This rather reminds me of some ancient scriptures that used neither vowels nor spaces.) Here's another history of zero.
This is utterly fascinating to me! It was not merely the fact that the Arabs created Arabic numerals (0, 1, 2, 3, etc.); it's that they were "philosophically neutral" enough to give a null placeholder its due.
And some placeholder it's turned out to be. Add a couple zeroes to 1 to make it a hundred, another to make it a thousand, three more to make it a million. But then it gets complicated. There's disagreement throughout the world how many zeroes are needed to make a billion, trillion and so forth. That's probably why one is prone to see designations such as 10 to the 12th power rather than having it stated it as trillion (U.S.) or billion (much of the rest of the world). Check out this link and look for the "add zero" file, for a humorous take on this.
Once zero is given a value, the notion of negative numbers can evolve. In the winter, we use them all the time when discussing temperature, for instance. Unfortunately, there are two popular scales, Celsius (called Centigrade when I was growing up), used by most of the world, and Fahrenheit, in use primarily in the metric-resistant United States. Thus: 0 degrees Celsius is 32 degrees Fahrenheit. 0 degrees Fahrenheit is -17.78 degrees Celsius. Cold and colder. The scales are the same at -40; here's a temperature converter.
Then there is absolute zero, the point at which there is a "theoretical absence of all thermal energy." By definition, that is at 0 degrees on the Kelvin scale (−273.15 C, -459.67 F).
Collins Helium Cryostat that freezes elements to absolute zero. September 1948
Once the concept of zero and negative number takes hold, then other concepts involving the word "zero" got introduced. Zero sum, for instance, suggests that some people are advantaged, and others disadvantaged in a transaction, and once you add up the pluses and the minuses, the sum is equal to zero. Or to quote John Mellencamp, "there's winners and there's losers." Compare this concept to win-win (or, I suppose, lose-lose.)
Zero hour refers to the end of the countdown to particular event, whether it be planned or unforeseen.
I'll end this with a song by Joan Armatrading, one of two "name" artists I've sactually seen twice (the other being the Temptations), doing Down to Zero.
Jerome McLaughlin buying war bond from rural mailman Mark Whalon making rounds in sub-zero weather. East Dorset, VT, US; December 1942