The moment you are born you are 0 years old (or perhaps 0.75 years old, but we don't usually recognize that). We count from zero in this case, at least implicitly.
In some cultures you are considered 1 the moment you are born, so the zero indexing isn't universal here, but typical in North America as noted earlier.
Typical counting of things starts from 0. If you count apples you implicitly start at zero and add 1 for each apple. If you count age, you start at birth (0) and count years; one for each birthday. That isn't zero based. The difference is the index of the item between the starting point and the next item. In zero based this item is number 0, in one based, this item is number 1. The first year of life is generally considered the year following birth.
This is a philosophically deep point which took me a long time to grasp.
There is a narrowing from "nothing at all" to "zero apples" which doesn't happen 'in the world' but is a necessary precondition to counting apples. The existence of any apple is a requirement for there to be zero of them before you put anything in the basket.
I just dealt with this problem(how to store periodic events(including birthdays)). It is a surprisingly difficult problem. After reading up on postgres interval types my latest attempt uses them to store events, where a per year event(like a birthday) is stored as "2 months 15 days". it turns out the postgres project has put quite a bit of thought into making interval types work as expected with regards to months, not an easy task when you consider how difficult it is to treat dates mathematically.
The nice part is that now February 29 "just works" the downside is the impedance between how months and days are numbered and a how an offset from the epoch(beginning of the year) is defined. January 3rd(1-3) is stored as "0 months 2 days" as when it hits, 0 months have passed and 2 days have passed.
So the specific case of February 29 hits when 1 month has passed and 28 days have passed. 3 years out of 4 this will be the same as "2 months 0 days"(3-1) but every forth year this will be(2-28). As an aside, and the specific reason I went with interval types, every event past feburary 29 works just fine with or without a leapyear, that is, the extra day in the middle does not mess up the offset to days after it.
Honestly I curse a little as I wish months and days were 0-based. At least clocks get this right, almost, 12 hour clocks are a special breed of stupid. start at 12, then go to 1 and proceed up to 11. 24 hour clocks properly start at 0. The worst part about 12 hour clocks is that it is almost correct, replace the 12 with a 0 and it every thing be the same but now it makes sense from a moduler math point of view.
You're just 1/4 of the age of everyone else born the same year. You have the same number of laps around the sun as those people, but you've definitely had fewer birthdays. It's a common joke for leap year babies.
The counting activity doesn't begin when the first item is registered; it begins when the counter is initialized to zero. A decision is made to begin counting, along with the realization that nothing has been counting yet. That's when counting has started. When the first item is seen, the counting is then continuing.
Suppose your job is to count some events. You check in for work at 8:00 a.m., but the first event has not registered until noon. By your logic you should not be paid for four hours, because you're paid to count, and counting started at 1.
I don't think your definition is complete. We can count a set by mapping its elements to the natural numbers, and then identifying that number which is highest. However, we must have a provision for identifying zero as the highest when the set and mapping are empty.
Do you know the definition of countable? A set S is countable if there is a one-to-one mapping from S to N where N is the natural numbers. Do you know that 0 is not a member of the natural numbers? We literally start counting at 1 by definition of countable.
> Equivalently, a set S is countable if there exists an injective function f : S → N from S to N; it simply means that every element in S corresponds to a different element in N.
Defining N is usually done via a successor set, on which case 0 makes no sense to include.
Standard construction of ordinals is that each ordinal is the set of all its predecessors. (0 has no predecessors , hence 0 is the empty set.) (And so finite ordinals have the same ordinaliity as cardinality).
Birthday[0] gives you an out of range exception, since there is no birthday called 0th. Birthdays are [first,second,..] indexed from 1: brithday[1] = first, birthday[2] = second, and so on. That's what indexing a series from 1 means.
Ok, use the baker and cup as an example. If you have an empty cup and put half of a cup of flour in it, you now have 0.5 cups of flour. Notice the zero before the ".5". That is us, normal humans, realizing that until you add enough to have 1 of something, you have between 0 and 0.999 repeating.
No, it just means we have a different notion of what a year is in regards to age. Similar to how different cultures can use different units of measurement for length, mass, etc.
Yes, exactly. One of which carries an implicit zero indexing. The date of birth doesn't disappear just because you decided to use a different measuring device.
No, it doesn’t carry an implicit 0 index. Measuring age (in the West) is like measuring distance. You start at 0, but that doesn’t mean the first item is at index 0.
No, old calendar systems are one indexed. In those system, there is literally no year zero; the first year is year one. This leads to crazy things like year 100 being part of the "first century" and year 101 being part of the "second century".
That is not the case with age or birthdays which are, thankfully, zero indexed. The first year of human life is age=0, birthdays=0.
If you don't care then sure, it's not crazy, but if you did care then believe me, it is crazy. Crazy enough that astronomers[0] and software engineers[1] rebelled against the historian's practice and renamed the years preceding 1 AD in the proleptic gregorian calendar year 0, year -1, year -2, et cetera. A major benefit of this is it allows the leap year pattern to stay consistent and the rule to remain legibile for all years, going back before 1 AD. It's also nice because it lets us say "the 90's were the last ten years of the 20th century" and be correct.
Haha, this thing is messed up. Your "first birthday" is technically second, because the first was at your, well, day of birth. But we people love to complicate things and count 1st birthday as a number of annual celebration events after the first mm-dd of birth. Off by one as it is.
Elapsed time timers start at 0. Time is continuous. The elapsed time being “out of the womb”, that we call “age”, starts near 0. Five minutes after birth, the baby has been in the world for, or it’s age is, five minutes. If someone asked how old a new baby is you could hear “3 weeks”.
Another definition might be from conception. But birth being “one year old” is illogical. The sperm didn’t even exist yet, one year before birth.
Your mistake is using years - use milliseconds (or nanoseconds) when you wish to express a duration. Years don't even have the same duration/length (leap years, and leap seconds)
And before an hour has even passed, we'd probably say "minutes old" or perhaps "not even an hour/day old", all to avoid saying "zero days/months/years old". But some might still say zero days old, and they'd be both understood and correct (at least logically if not stylistically). That's the "implicit zero" everybody is talking about. We avoid saying it, but that's just a convention of communcation. Logically it's there. You're zero days old before you're one day old.
In some cultures you are considered 1 the moment you are born, so the zero indexing isn't universal here, but typical in North America as noted earlier.