No, they don’t have to be rational. It’s counter-intuitive but you can accurately draw a line with an irrational length, even though you can’t ever finish writing that length down.
The simplest example is a right-angled triangle with two side equal to 1. The hypotenuse is of length root 2, also an irrational number but you can still draw it.
Thanks for the answer. I’m confident you’re correct but I’m having a hard time wrapping my head around drawing a line with an irrational length. If we did draw a right angled triangle with two sides equal to 1cm and we measured the hypotenuse physically with a ruler, how would we measure a never ending number? How would we able to keep measuring as the numbers after the decimal point keep going forever but the physical line itself is finite?
It’s not that it can be measured forever, it’s just that it refuses to match up with any line on the ruler.
For a line of length pi: it’s somewhere between 3 or 4, so you get a ruler and figure out it’s 3.1ish, so you get a better ruler and you get 3.14ish. get the best ruler in existence and you get 3.14159265…ish
…and when you go deep enough you suddenly lose the line in a jumble of vibrating particles or even wose quantum foam, realising the length of the line no longer makes sense as a concept and that there are limits to precision measurements in the physical world.
Irrational numbers can be rounded to whatever degree of accuracy you demand (or your measuring instrument allows). They’re not infinite, it just requires an infinite number of decimal places to write down the exact number. They’re known to be within two definite values, one rounded down and one rounded up at however many decimal places you calculate.
You’re talking about maths, maths is theoretical. Measuring is physics.
In the real world you eventually would have to measure the atoms of the ink on your paper, and it would get really complicated. Basically … you can’t exactly meassure how long it is because physics gets in the way (There is an entire BBC documentary called “How Long is a Piece of String” it’s quite interesting).
No, they don’t have to be rational. It’s counter-intuitive but you can accurately draw a line with an irrational length, even though you can’t ever finish writing that length down.
The simplest example is a right-angled triangle with two side equal to 1. The hypotenuse is of length root 2, also an irrational number but you can still draw it.
Thanks for the answer. I’m confident you’re correct but I’m having a hard time wrapping my head around drawing a line with an irrational length. If we did draw a right angled triangle with two sides equal to 1cm and we measured the hypotenuse physically with a ruler, how would we measure a never ending number? How would we able to keep measuring as the numbers after the decimal point keep going forever but the physical line itself is finite?
It’s not that it can be measured forever, it’s just that it refuses to match up with any line on the ruler.
For a line of length pi: it’s somewhere between 3 or 4, so you get a ruler and figure out it’s 3.1ish, so you get a better ruler and you get 3.14ish. get the best ruler in existence and you get 3.14159265…ish
…and when you go deep enough you suddenly lose the line in a jumble of vibrating particles or even wose quantum foam, realising the length of the line no longer makes sense as a concept and that there are limits to precision measurements in the physical world.
Irrational numbers can be rounded to whatever degree of accuracy you demand (or your measuring instrument allows). They’re not infinite, it just requires an infinite number of decimal places to write down the exact number. They’re known to be within two definite values, one rounded down and one rounded up at however many decimal places you calculate.
You’re talking about maths, maths is theoretical. Measuring is physics.
In the real world you eventually would have to measure the atoms of the ink on your paper, and it would get really complicated. Basically … you can’t exactly meassure how long it is because physics gets in the way (There is an entire BBC documentary called “How Long is a Piece of String” it’s quite interesting).
Is that basically the coastline paradox?