this post was submitted on 30 Nov 2023
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You ever see a dog that's got its leash tangled the long way round a table leg, and it just cannot grasp what the problem is or how to fix it? It can see all the components laid out in front of it, but it's never going to make the connection.

Obviously some dog breeds are smarter than others, ditto individual dogs - but you get the concept.

Is there an equivalent for humans? What ridiculously simple concept would have aliens facetentacling as they see us stumble around and utterly fail to reason about it?

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[–] [email protected] 3 points 11 months ago (2 children)

There's lots of proofs for this but this is the simplest one.

.333... = 1/3
.333... • 3 = .999...
1/3 • 3 = 1
Therefore .999... = 1

[–] [email protected] 1 points 11 months ago* (last edited 11 months ago) (3 children)

Why is .333 being treated the same as a third?

You could have .3 of 2.7 and that wouldn’t be a third. So I don’t see why .3 times 3 would be anything other than 0.9?

[–] [email protected] 3 points 11 months ago

In this case you literally divide 1 by 3. And that's 0.3333 . And if you multiply 1/3 by 3 you get 1 and if you multiply 0.3333 by 3 you get 0.9999. So these two are the same.

[–] [email protected] 3 points 11 months ago (1 children)

.333... Not .333

The "..." Here represents an infinitely repeating number.

In this context 1/3 = .333...

[–] [email protected] 1 points 11 months ago* (last edited 11 months ago) (1 children)

Just pretend I added dots. But that still doesn’t change anything?

Imagine a pizza, I can divide that pizza into halves, thirds, quarters, etc. because conceptually they represent splitting a defined thing into chunks that are the sum of its whole. 1/3 can exist in this world of finites.

0.333… is unending. I can’t have 0.333… of a pizza, because 0.333… is a number and that makes as much sense as saying I’ll have 2.8 pizza. Do I mean 2.8 times a pizza, 2.8% of one? Etc.

[–] [email protected] 1 points 11 months ago (3 children)

1/3 being equal to .333... Is incredibly basic fractional math.

Think about it this way. What is the value of 1 split into thirds expressed as a decimal?

It can't be .3 because 3 of those is only equal to .9
It also can't be .34 because three of those would be equal to 1.2

This is actually an artifact of using a base 10 number system. For instance if we instead tried representing the fraction 1/3 using base 12 we actually get 1/3=4 (subscript 12 which I can't do on my phone)

Now there are proofs you can find relating to 1/3 being equal to .333... But generally the more simplistic the problem, the more complex the proof is. You might have trouble understand them if you haven't done some advanced work in number theory.

[–] [email protected] 2 points 11 months ago (1 children)

Is there a number system that's not base 10 that would be a "more perfect" representation or that would be better able/more inherently able to capture infinities? Is my question complete nonsense?

[–] [email protected] 1 points 11 months ago

Different bases would have different things they cannot represent as a decimal, but no matter what base you can find something that isn't there.

For real world use base 12 is much nicer than base 10. However it isn't perfect. Circles are 360 degrees because base 360 is even nicer yet, but probably too hard to teach multiplication tables.

[–] [email protected] 1 points 11 months ago* (last edited 11 months ago) (1 children)

I get its basic shit that’s over my head. I’m just trying to understands

If the only reason is because 1/3 of 1 = 0.9, than id say the problem is with the question not the answer? Seems like 1 cannot be divided without some magical remainder amount existing

If I have 100 dogs, and I split them into thirds I’ve got 3 lots of 33 dogs and 1 dog left over. So the issue is with my original idea of splitting the dogs into thirds, because clearly I haven’t got 100% in 3 lots because 1 of them is by itself.

Likewise would 0.888… be .9? If we assume that magical remainder number ticks you up the next number wouldn’t that also hold true here as well?

And if 0.8 is the same as 0.888888888…, than why wouldn’t we say 0.7 equals 0.9, etc?

[–] [email protected] 2 points 11 months ago* (last edited 11 months ago)

I get its basic shit that’s over my head.

It's over the head of everyone. That's why I shared it here.

Likewise would 0.888… be .9?

No, but 0.899... = 0.9. This only applies to the repeating sequences of the last digit of your base. We're using base 10 so it got to be 9.

If I have 100 dogs, and I split them into thirds I’ve got 3 lots of 33 dogs and 1 dog left over. So the issue is with my original idea of splitting the dogs into thirds, because clearly I haven’t got 100% in 3 lots because 1 of them is by itself.

Then you split the leftover dog into 10 parts. Why 10? Because you use base 10. Three of those parts go to each lot of dogs... and you still have 1/10 dog left.

Then you do it again. And you have 1/100 dog left. And again, and again, infinitely.

If you take that "infinitely" into account, then you can say that each lot of dogs has exactly one third of the original amount.

[–] [email protected] 2 points 11 months ago (1 children)

0.333... represents 0.3 repeating, which has an infinite number of 3s and is exactly equal to 1/3.

[–] [email protected] 4 points 11 months ago (1 children)

I don't agree that they are the same.

It's just that the difference is infinitely small

[–] [email protected] 0 points 11 months ago (1 children)

The difference is zero, so they’re equal.

[–] [email protected] 0 points 11 months ago

Well, you state that as a fact, but I’m going to say that the difference is infinitely small, so they are equal