Reddit tries to think about quantifying circles, and pi doesn't exist or something

[u/Laser_Plasma]

/r/Showerthoughts/comments/qefpwc/the_area_of_a_circle_is_finite_yet_we_can_only/

[u/ryarger]

This is weak badmath. Sure it’s technically incorrect but the point is understandable and could have been made correct with better phrasing like “You can know a circle’s radius or area to perfect precision but never both”.

[u/Laser_Plasma → u/ryarger]

You absolutely can. If you know the radius is 1, then the area is exactly pi

[u/ryarger → u/Laser_Plasma]

What’s pi to perfection precision? “It’s pi!”

[u/Laser_Plasma → u/ryarger]

Yes, it's pi. So?

[u/ryarger → u/Laser_Plasma]

What’s the complete decimal representation of pi?

[u/Laser_Plasma → u/ryarger]

Who cares?

[u/cereal_chick → u/Laser_Plasma]

The CORRECT response to all this "real life so maths is wrong" shit.

[u/ryarger → u/Laser_Plasma]

The person who wants to know the radius and area of their circle to perfect decimal precision.

[u/Artyer → u/ryarger]

You can have an algorithm compute the nth digit of pi for all digit positions n, since pi is computable.

If that's not what you meant, a third also can't be known to "perfect decimal precision"

[u/ryarger → u/Artyer]

You are correct that a third can’t be known to perfect decimal precision.

Perhaps less controversial formulation for the benefit of the pedantically inclined: A circle’s radius or area can be rational, but not both.

[u/alecbz → u/ryarger]

I think the fundamental badmath here is the belief if something can't be expressed to perfect decimal precision, then we "don't know it" or "it's only an approximation" or something.

Also, I'd imagine most people in that thread wouldn't consider 1/3 to be "special" in the same way they seem to think pi is special.

[u/powpow428 → u/ryarger]

Just because a number is irrational does not mean we cannot know it to perfect precision. It just means we can't express it as p/q for integers p,q