Where did 0 come from? The concept of the modern zero was invented in India, but the idea of a placeholder for numbers was thought up by the Mesopotamians.
We take the idea of the number 0 for granted. We use it regularly throughout the day (probably) and many of the things we use would not function without it. It is a part of the programming for your phone and for the algorithm that pushes my articles down to the darkest parts of the web. However, that concept has only existed since relatively recently. That is not so strange when you think about it because zero means nothing, and why would you have a number that means nothing? The very concept of numbers is to count things. You would never count nothing because there is nothing there to count.
Something similar to zero became necessary when counting systems changed. Early counting systems simply counted the number of things that there were. They used marks or symbols. One mark for one thing, two marks for two things, and so on. However, humans can only rapidly count groups of four things. Any more than that and we can’t do it quickly. That is why a lot of the early counting systems, like Roman numerals, use marks for one, two, three, and then change to other symbols. I, II, III, IV, V, VI etc. There is no need for a zero in a system that just counts what is there. The problem with these systems is that numbers get very long. An easier way is the system that we use today. You have the numbers 1 to 9, and then you have columns for the place values. The first column is for the units. Everything up to nine. The next column is for the tens. Everything up to 90. And the last column is for the hundreds. Everything up to nine hundred. This makes numbers shorter, but you have the problem of what to write when there is no value in that column. Today, we write a zero, but in the early days of counting, the Mesopotamians just left a space. This is not a zero, but it is the first instance of nothing being written. This was approximately 4,000 years ago. The Babylonians came next. They used two small wedges to indicate no values in one of the numerical columns. This is still not a number, though. The Mayans also used a symbol that looked like a zero as a placeholder, but this was also not a separate number. Zero as a placeholder spread through other civilizations as well, but it was never an actual number.
The first time zero was used as a number was in 628 AD in India. It probably evolved in India independently and started out as a concept of emptiness, or of nothingness. It was called śūnya, and the idea first appears in India in 458 AD. The rules for the use of zero were set down in 628 AD by an astronomer and mathematician called Brahmagupta, but he talks about zero as though it is already known about, which implies that it appeared before his time. He just clarifies the rules.
The concept of zero went from India to Arabia, where it was considered a regular number. In Arabic, zero was called sifir, which was a translation of the Hindi śūnya, which meant empty. From Arabia, it went into Europe via Venice. In Italian, sifir became zefiro, which later became zero.
The symbol for zero also evolved over time. Early civilizations used hash marks or other marks to indicate a space. In Mayan, it was portrayed as a tortoise shell shape, which is roundish. In ancient Greece, it was written as a small circle underneath a horizontal line. It started out as the Greek letter omicron (ό), and ended up as a smaller circle and a longer line. In China, it was written as a O, but it might just have been a square with rounded corners. In the early Indian manuscripts, zero was written as a solid black dot. There are some examples of zero being written as a circle in India, but it was more often a dot. When zero travelled to the Middle East and then moved up into Europe it gradually became a larger circle. This was probably because a dot could be mistaken as punctuation or easily missed. Also, as zero became a number in its own right, it was written the same size as all of the other numbers. And this is what I learned today.
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Sources
https://www.history.com/news/who-invented-the-zero
https://www.scientificamerican.com/article/what-is-the-origin-of-zer
https://www.ox.ac.uk/news/2017-09-14-earliest-recorded-use-zero-centuries-older-first-thought
https://en.wikipedia.org/wiki/Bakhshali_manuscript
https://www.cbc.ca/radio/ideas/zero-number-series-ideas-cbc-1.6977700
https://www.livescience.com/27853-who-invented-zero.html
https://en.wikipedia.org/wiki/0
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