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☖ Forums → Discussion Forum → Pi is (still) wrong?
Pi is (still) wrong?
2011-03-15, 1:37 AM #1
Since yesterday was pi day, I came across posting this video on Facebook:

To me, this seems to make sense, which raises my own suspicions, especially since mathematics isn't my strong suit. From the more mathematically-minded, I ask of you: does what this video present have merit, or is it a bunch of rubbish?
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2011-03-15, 2:14 AM #2
She's stupid and her voice infuriates me....


...is what I would have said had I not watched the whole video, that's quite smart and I would like to see someone with a math background explain why it isn't this way.
2011-03-15, 4:14 AM #3
Long live tau
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try: command not found
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2011-03-15, 6:42 AM #4
The issue is at best a minor inconvenience for only the dumbest students.
2011-03-15, 7:20 AM #5
Armsocks!? is that rob?
[01:52] <~Nikumubeki> Because it's MBEGGAR BEGS LIKE A BEGONI.
2011-03-15, 7:23 AM #6
Originally posted by Jon`C:
The issue is at best a minor inconvenience for only the dumbest students.


Elegantly put as always, Sire.
2011-03-15, 8:10 AM #7
It really isn't as confusing as they try to make it out to be. If pi confuses you, you should probably quit math then and there, because things that come after it are going to rape your brain.

Basically they're proposing replacing pi to make one major geometric formula cleaner, at the expense of making an already clean geometric formula more complex (area of a circle). There's really not much to be gained by doing it, not to mention randomly rewriting core formulas of geometry that have been in use for ages and expecting people to embrace such a trivial change is just, well, silly.
2011-03-15, 8:24 AM #8
We could get rid of 2*pi just as easily by defining 1 radian = angle with arclength of 1 diameter.
2011-03-15, 8:28 AM #9
Note: just as easily
2011-03-15, 8:32 AM #10
I see her point, but it's just a factor of 2. It's utterly arbitrary.

I like my bucking equations / strut curves in terms of pi, missy.
2011-03-15, 8:32 AM #11
Originally posted by Darth:
It really isn't as confusing as they try to make it out to be. If pi confuses you, you should probably quit math then and there, because things that come after it are going to rape your brain.

Basically they're proposing replacing pi to make one major geometric formula cleaner, at the expense of making an already clean geometric formula more complex (area of a circle). There's really not much to be gained by doing it, not to mention randomly rewriting core formulas of geometry that have been in use for ages and expecting people to embrace such a trivial change is just, well, silly.


Not understanding is the last reason to quit. If you don't understand something, you should work at it until you DO understand it.
2011-03-15, 8:48 AM #12
Martyn, this isn't even a joke: I get really aroused when you talk about structural engineering and ****. I'm not kidding. Please talk about it more, it excites my architectural sensibilities.
2011-03-15, 8:52 AM #13
I've heard this argument before and I've yet to find a compelling reason against it, other than the fact all of us who learnt to use pi would have to adjust our thinking a bit...

For the amount of hassle that would be caused over what is a factor of two, I don't really think it's worth it.

It's one of these discussion that I find theorists doing quite often, I listen for about 2-3 minutes and then decide to actually go do something useful other than just talking (excuse the pun) in circles for eternity.
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2011-03-15, 8:54 AM #14
I like the last few seconds at the end of the video with the pies.... how she has one pie, and two pies. she's pie-winning.

oh and I guess the math stuff was interesting.
The Gas Station
2011-03-15, 8:56 AM #15
Originally posted by poley:
For the amount of hassle that would be caused over what is a factor of two, I don't really think it's worth it.


Yeah, if we started making these kinds of changes I could think of much better places to start.

f[sup]-1[/sup](x), f(x)[sup]-1[/sup], f[sup]2[/sup](x), f(x)[sup]2[/sup], sin[sup]2[/sup](x), sin(x)[sup]2[/sup]
2011-03-15, 9:09 AM #16
Originally posted by saberopus:
Martyn, this isn't even a joke: I get really aroused when you talk about structural engineering and ****. I'm not kidding. Please talk about it more, it excites my architectural sensibilities.


I'm leaving work now, but I can leave a large tirade here another time...

...and talk about flanges.

Mmmmmm... flanges.
2011-03-15, 10:20 AM #17
Originally posted by Darth:
It really isn't as confusing as they try to make it out to be. If pi confuses you, you should probably quit math then and there, because things that come after it are going to rape your brain.

Basically they're proposing replacing pi to make one major geometric formula cleaner, at the expense of making an already clean geometric formula more complex (area of a circle). There's really not much to be gained by doing it, not to mention randomly rewriting core formulas of geometry that have been in use for ages and expecting people to embrace such a trivial change is just, well, silly.


The argument isn't that it makes just one formula cleaner, it's that it makes loads of things cleaner:

http://tauday.com/

Whilst a factor of 2 is trivial, if its presence causes needless complexity it just makes maths more ugly.
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2011-03-15, 4:21 PM #18
Her argument makes no sense. Radians and pi are different things. Just because we measure radians in multiples of PI does not mean that you can pretend the unit of measure is 'PI' and not radians. If you asked for '1/8th pi' any sane person will believe you asked for 1/8th pie. She seems to think you're asking for a slice with an angle of 1/8th radians. Except, that's not what you said. Because pi is a number. Not a unit of measure.

Incidentally, changing radians such that 1r = 360 degrees would make the radius of the unit circle radians are based on 0.5. All you did was move the factor of 2 somewhere else.

Changing PI to C/R instead of C/D, though, makes absolutely no difference. It's pretty ****ing arbitrary.
2011-03-15, 4:29 PM #19
Originally posted by JM:
Radians and pi are different things.


central angle of 1 radian = central angle with arclength equal to 1 radius.

Edit: this means the definition of pi and the definition of a radian are equivalent.

Edit 2: that said, the definition of tau does not have to change the definition of the radian. They are compatible.
2011-03-16, 1:37 AM #20
"mathematics should be as eloquent and as beautiful as possible" - says who?

pi is just a constant, it's function doesn't change whether you multiply it by two or not.. why fix what's not broken?

also, the "confusion" that she claims to exist about the current pi isn't even confusing. in elementary geo, when students are actually learning this math, the concepts of circumference and area are probably more confusing than the constants used
2011-03-16, 1:42 AM #21
Let's also not forget that in practical terms, (measurement of real objects for instance) diameter is king.

How big is that pipe? How wide a hole must I drill? What size are your tires?

All relate physically to diameter, not radius. Radius might well be useful on paper, but out in the real world of bores, bolts, drills, pipes, wheels and what have you, people need to work with diameters.

How would this girl propose to measure the radius of a hole drilled in a steel plate? She'd be forced to measure the diameter and then divide by two.
2011-03-16, 1:55 AM #22
nah, just wedge the calipers in at an angle. it'll be close enough.
2011-03-16, 1:58 AM #23
We'll say it's about 3.

FIBR

(**** it, it'll be right.)
2011-03-16, 4:50 AM #24
Quote:
Edit: this means the definition of pi and the definition of a radian are equivalent.
No it doesn't. pi is still a number, not a unit of measure.
2011-03-16, 7:36 AM #25
Originally posted by JM:
No it doesn't. pi is still a number, not a unit of measure.


he is right. pi is a ratio between a circles radius and circumference, radians are a measurement of angle
2011-03-16, 7:52 AM #26
A => B
B => A

∴ A <=> B

A and B are equivalent.
2011-03-16, 8:32 AM #27
I think it makes more sense. Since a circle is defined as a point and a radius in an equation, pi should be defined using the radius.
2011-03-16, 4:20 PM #28
Quote:
A => B
B => A

∴ A <=> B

A and B are equivalent.


No, they still aren't. You can't assume you are correct, then use that assumption to prove you are correct, which is what you have done.

The fact that radians are measured in multiples of pi does not mean that radians are pi or pi are radians. Pi is just a number. It's no different from 1 or 2 or 5.382213783. Radians are just a unit of measure. It's no different from meters or grams or kilowatts. Saying that pi is radians is as sensible as saying that e is stone.
2011-03-16, 4:43 PM #29
Yeah but both pi and radians are defined from the same mathematical concept. Even if they are different from each other, they are both derived from the circle.
Warhead[97]
2011-03-16, 5:02 PM #30
Originally posted by JM:
Saying that pi is radians is as sensible as saying that e is stone.
'Equivalent' does not mean what you think it means in a context of mathematics.
2011-03-17, 1:23 AM #31
She has arm-warmers. Hence, her opinion is ****.

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