A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.
Rules
This is a science community. We use the Dawkins definition of meme.
Meme of two women fighting while a man smokes from a pipe in the background.
The women fighting are labeled "mathematicians defining pi" and "engineers just using 3 because it's within tolerance"
The man smoking is labeled "astrophysicists" and the pipe is labeled "pi = 1"
I use 3 ^16^/~113~
At least do 22/7
(355/113)/ pi = 1.0000000849136...
That's way more numbers to remember than 1/7 above 3
You're a monster. I love it
Only basic math. You can convert Pi even more precise, but I think to 6 decimals is enough.
Computer science: pi is O(1)
Is it actually? I'll admit im pretty rusty on time complexity, but naively I'd think that pi being irrational would technically make even reading or writing it from memory an undecidable problem
It's usually a constant (or several ones with varying degrees of accuracy and size)
It all depends on the precision you need. You could use an infinite series to get to the precision needed but for most use-cases it’s just a double baked into the binary itself, hence O(1)
If you're trying to calculate it, then it's quite difficult.
If you just want to use it in a computer program, most programming languages have it as a constant you can request. You get to pick whether you want single or double precision, but both are atomic (a single instruction) on modern computers.
Do said atomic instructions produce pi though, or some functional approximation of pi? I absolutely buy that approximate pi is O(1), but it still seems like a problem involving a true irrational number should be undecidable on any real turing machine
I heard once π²=10 is fairly accurate approx and thus g=π²=10 in astrophysics where people thinks in order of magnitude, not value.
But my engineering ass is telling assumptions with larger than 50% difference from actual value may cause issues on order of magnitude if the value is used multiple times and isnt it better be like 5=1/2×10?
That's because your engineering ass needs things to be physical and sane. Physics is a field for the mentally unwell to sink further into insanity while incoherently scribbling greek letters on every available flat surface.
On a more serious note, yeah you absolutely have to be careful about where you apply really ambitious simplifications like that. There are plenty of mathematical regimes where you can use natural units (this is the term to look up if your interest extends further) and simplify your reference frame by a hell of a lot though. Setting the speed of light to 1 is also a hell of a drug, and brother I've got an addiction
This image is a two-panel meme utilizing a blurry, chaotic photo of individuals seemingly engaged in a mock fight and a separate photo of a person appearing to conduct a science experiment with a small flame, possibly under the influence of poor judgment.
In the left panel, the text "MATHEMATICIANS DEFINING PI" is superimposed over two individuals engaged in a dramatic physical altercation, one holding the other back. A third person, who is uninvolved but present, is labeled "ENGINEERS JUST USING 3 BECAUSE IT'S WITHIN TOLERANCE." This suggests a hierarchy of concern regarding the numerical precision of π (pi), with mathematicians caring deeply, engineers demonstrating relaxed standards, and general chaos ensuing.
In the right panel, a shirtless person crouches and conducts a questionable experiment involving a lighter and a small pipe. The caption "ASTROPHYSICISTS" is positioned above their head, and below is the phrase "PI = 1." This implies a level of approximation so extreme it borders on parody, indicating astrophysicists allegedly use such simplifications in the name of cosmic-scale practicality.
The overall composition is an exaggerated commentary on varying standards of numerical precision in different disciplines, presented through low-resolution imagery and humorous juxtaposition.
As an Astrophysicist, I have never seen anybody use pi=1, you just leave the character, it's anyway better to read, is not like you do any calculations by hand anyway. More common is c=hbar=kB=1, but that is not an approximate, is a gauge in another unit system. Also... Astronomy is not astrophysics...
"is not like you do calculations by hand anyway"
... get off my lawn, whippersnapper.
38 digits of pi can get the circumference of the visible universe to within a single hydrogen atom.
10 digits gets the diameter of the earth to within an inch.
Thank you for subscribing to Daily Spacey Math Facts
The real comment mvp. You deserve every positive vote my post got
And just two digits introduces less error than your average terrible model
Wow, what do you have against models? I mean, I know that the trope is that they aren't very smart, but the same trope applies to firemen, so why pick on models?
out of curiosity... does that first fact account for the continued expansion of the universe?
It works at the current 93 billion light years of observable universe (46ish in every direction)
as an engineer, a lot of languages (even proprietary ones) have a built-in constant pi variable because it is so ubiquitous - its easier and more readable to use pi than 3........
And then you’re using C++ and they scold you for including cmath for just M_PI because it increases compilation times.
As they should, if that's the only thing you are using it for, don't introduce a whole header file, just put the following in the constants.h or equivalent that the proj for sure has:
#define M_PI 3.14159265358979323846264338327950288
Yes, it's literally what math.h has defined.
We're talking about engineers here! We're using MATLAB or Python if we're programming at all.
You can't say that for all engineers. I'm one and the biggest part of my job is programming in C++
Just wanted to say something similar. Any low latency high frequency code is written in c++, c or assembler. And that’s engineers work usually.
Your not writing regular python code, your writing a special subset of python intended for engineers and scientists called "bad python code"
My code is not intended to be run by any idiots but myself! Anyways why can't i make sense of what i have written just a month ago?
As a comp sci that interacts a lot with engineers, I feel this in my soul.
They do? Why not provide some explanation?
Somebody else already said it, but that's what the title is.
Longform: a lot of calculations that happen in astro deal with distances so large so large that only order of magnitude changes actually meaningfully affect the end result. To connect to a more common topic, here's a joke.
"Whats the difference between a million dollars and a billion dollars?"
"About a billion dollars"
This joke works for the same reason; 1 billion is so many orders of magnitude larger than 1 million that (1,000,000,000 - 1,000,000 = 1,000,000,000) is only incorrect by ~0.1%, even though substituting 0 for 1 million in that equation seems ridiculous on the face of it. Substituting 1 for pi has similarly minimal errors (tbh it usually matters waaaaaaaaay less than .1% error) in a lot of astro math
In astronomy, the important part of the number is often just how big it is (that is, the exponent). Multiplying by pi doesn't change much in that.
The explanation is in the title.
It isn't an explanation
Astronomy often has pretty high error bars on their measurements (distance, size of stuff, etc).