Thread: Can we predict the number of people who will ever live?

Imagine a hypothetical situation where the people who will ever get born are 50 billions. If each one of them knows how many people were born before him, he could make a prediction on how many people will be born after him by doubling that number. This would be roughly accurate in the most cases, theoretically even in the case that the answer is "infinity" (if I'm not wrong here).

Therefore, since it's estimated that 100-115 billion people have lived so far (source: Wikipedia), would we expect about as much, if we ignore everything else we know?

I feel that there is a good chance that I'm wrong, but I've checked this hypothesis several times and I don't see any mistakes, except that I'm not sure about the case where infinite people will be born.

yep you are wrong-there are a tremendous number of factors to consider-not simple multiplication

Originally Posted by fizzlooney

yep you are wrong-there are a tremendous number of factors to consider-not simple multiplication

I know there is. But can't I just ignore them and assume that they are unknown? After all, it did work in this way in the hypothetical situation.

Blackened, fizz is correct, let me explain. When I was born there were 3 billion people on this earth,
now there are 7. I feel the factors fizz is speaking of are these, we have limited resources to support
more than 9 billion, and what your point is, with respect, I fail to understand.
I feel your question is more academic than realistic in the real world.
How can you assume something is unknown because you choose to ignore it? How can you
assume not knowing when you are aware of it?
And, with respect, do you really understand what hypothesis means?

nokton.

Originally Posted by Blackened

he could make a prediction on how many people will be born after him by doubling that number.

I don't see the logic in that. It implies that everyone ever born was half way through the total number of people who will ever exist. That is obviously self-contradictory.

@nokton: I know stuff about the other factors. My point is that, if we ignore them in the example, the method worked, so I assumed that if we ignore them in real life, the method would work too, right? I will explain my method in the next paragraph in this post. As far as I know, "hypothesis" means an idea about the world that is theoretically explained (sometimes with some practical evidence), but is too unreliable and there is a good chance that it's wrong - in contrast of a theory - a theory is a hypothesis with some evidence behind it, usually (or "always" instead of "usually", I'm not sure) reliable.

@Strange: You are right, I presumed that certain parts of my explanation are obvious, while they aren't. Let me clarify it.

In my example, doubling the number of people who were born before you would have given 2 billion for a whole billion of the people - this is 25 times less than the real answer, for a whole 2% of the people. And for some people (like the first one million people), the answer would be a thousand times more inaccurate. However, if you take into account the last 1 billion, they would get a result that would balance out the first 1 billion. The point is that they balance out themselves, so that the mean result is exactly 50 billions. And the number they are the closest to is 50 billions.

I'm not sure if they really balance themselves out in the sense that allows me to make that conclusion, because the first 1 billion would get 2 billions (25 times less than 50 billions), and the last 1 billion would get 98-100 billions (just two times more than 50 billions).

Also, 90% of them would arrive at a number that is relatively close to 50 billions.

It's all useless speculation, since we don't know how long human civilization will last.

It's not going to tell us how long is it going to last, but IF it can give an estimation of it, then it wouldn't be useless. And if I don't have an error somewhere, then it can give us an estimation.

Originally Posted by Strange

Originally Posted by Blackened

he could make a prediction on how many people will be born after him by doubling that number.

I don't see the logic in that.

I don't either.

When will will stop being people?

You can predict whatever you want, but keep in mind the only thing in common among people who predict the future is they all get their predictions wrong.

Anyway, the earth is a complex system and trying to use linear modeling to predict its behaviour sets you up for an automatic fail.
You would do better trying to model it with complexity theory instead. Unfortunately that might take you to the edge of Chaos and render your prediction as a set of probailities instead of a single possibility.

I'm still trying to understand how they count everyone to determine just how many people are actually on this planet. Few countries have a census and that Is often skewed by false data that those answering the survey many times make.

I'm still trying to understand how they count everyone to determine just how many people are actually on this planet. Few countries have a census and that Is often skewed by false data that those answering the survey many times make

There are all kinds of statistical methods for computing fairly accurate numbers.

A good place to start would be here .... Gapminder: Unveiling the beauty of statistics for a fact based world view.