[HN Gopher] A wonderful coincidence or an expected connection: w...
       ___________________________________________________________________
        
       A wonderful coincidence or an expected connection: why p2 [?] g
        
       Author : signa11
       Score  : 335 points
       Date   : 2024-08-10 12:24 UTC (10 hours ago)
        
 (HTM) web link (roitman.io)
 (TXT) w3m dump (roitman.io)
        
       | levzettelin wrote:
       | He wouldn't be speaking like this if he was born on Mars.
        
         | edflsafoiewq wrote:
         | Sure he would, the meter would just be a different length.
        
         | baxtr wrote:
         | Finally an easy way to identify aliens!
        
           | samstave wrote:
           | How? Because they don't have a Venus?
        
         | alfiedotwtf wrote:
         | The pendulum from the Mars pole to Paris would be long indeed!
        
         | Maxatar wrote:
         | I thought they key insight of this article was if he were born
         | on Mars, then the meter would have been defined differently so
         | that gravity would still be 9.8 m/s^2.
         | 
         | I think what you meant to say was that he wouldn't be speaking
         | like this if people were born with 3 fingers.
        
       | mistercow wrote:
       | This is interesting, but I have to quibble with this:
       | 
       | > If you express this value in any other units, the magic
       | immediately disappears. So, this is no coincidence
       | 
       | Ordinarily, this would be extremely indicative of a coincidence.
       | If you're looking for a heuristic for non-coincidences, "sticks
       | around when you change units" is the one you want. This is just
       | an unusual case where that heuristic fails.
        
         | karmakurtisaani wrote:
         | Actually no, the whole equation boils down to the definition of
         | meter. Or rather, one of the earlier definitions.
        
           | mistercow wrote:
           | Yeah, I read the post. What I'm saying is "this relationship
           | vanishes when you change units, so it must not be a
           | coincidence" is a bad way to check for non-coincidences _in
           | general._
           | 
           | For example, the speed of sound is almost exactly 3/4 cubits
           | per millisecond. Why is it such a nice fraction? The magic
           | disappears if you change units... (of course, I just spammed
           | units at wolfram alpha until I found something mildly
           | interesting).
        
             | brians wrote:
             | Because the cubit is a measure of what a body can reach
        
               | Bjartr wrote:
               | How does that explain the relationship to the speed of
               | sound?
        
               | ValentinA23 wrote:
               | A bit out of topic, however
               | 
               | https://www.youtube.com/watch?v=0xOGeZt71sg
               | 
               | Note: I'm more inclined to think this is a coincidence
               | given that it establishes a link between the most
               | commented text and the the most commented building in
               | history. However I don't think these kind of
               | relationships based on "magic thought" should be
               | discarded right away just because they are coincidences,
               | and I'd be very interested in an algorithm that
               | automatically finds them.
        
               | ants_everywhere wrote:
               | I never thought of the cubit this way. It's an
               | interesting idea, but the cubit is the length of a
               | forearm, whereas you can reach around yourself in a
               | circle the length of your extended arm, from finger tip
               | to shoulder.
               | 
               | That would be somewhere between 1.5 to 2 cubits for
               | people whose forearm is about a cubit long.
               | 
               | I think the cubit is mainly a measure of one winding of
               | rope around your forearm. That way you can count the
               | number of windings as you're taking rope from the spool.
               | This is the natural way a lot of us wind up electrical
               | cables, and I'm sure it was natural back in the day when
               | builders didn't have access to precise cubit sticks.
               | 
               | I don't see the connection with the units and sound that
               | you're making. But it is kind of interesting to know that
               | sound travels about 3/4 of a forearm length per
               | millisecond. That's something that's easy to estimate in
               | a physical space.
        
             | jncfhnb wrote:
             | X^2 is a lot more interesting than x*0.0000743 or whatever
             | it is
        
               | satvikpendem wrote:
               | Why is it more interesting? Is it just more interesting
               | because we use such bases, or can it be interesting
               | inherently? That is the question that is being asked, and
               | why some say it's merely a coincidence.
        
               | jncfhnb wrote:
               | Well every number is the product of another number and
               | some coefficient. If it's a nice clean number then that
               | implies it could be the result of some scaling unit
               | conversion. But that should be sort of apparent. And it's
               | not super interesting if true.
               | 
               | If a number is another number squared then that implies
               | some sort of mechanistic relationship. Especially when
               | the number is pi, which suggests there's a geometric
               | intuition to understanding the definition.
        
               | satvikpendem wrote:
               | In other bases, it does not actually imply much, even if
               | it were squared. Maybe it really does make sense if it
               | existed in base 10 but I cannot see much if it were part
               | of other bases.
        
               | mistercow wrote:
               | Ok, then by that thinking, you should find it _really_
               | interesting that Earth escape velocity is almost exactly
               | ph^4 miles per second.
               | 
               | In fact, adding exponents here objectively makes it less
               | interesting, because it increases the search space for
               | coincidences.
               | 
               | What makes the case in the post most interesting to me is
               | that it looks at first glance like it _must_ be a
               | coincidence, and then it turns out not to be.
        
             | Waterluvian wrote:
             | Or the speed of light being almost a sweet 300 million m/s.
             | 
             | Or after-atmosphere insolation being somewhat on average
             | 1kw/m2.
        
               | ta1243 wrote:
               | I always find insolation and insulation to be such an
               | interesting pair of words
               | 
               | I guess the equivelent of "change the units" is "change
               | the language".
               | 
               | French: insolation et isolation
               | 
               | German: Sonneneinstrahlung / Isolierung
               | 
               | Spanish: insolacion / aislamiento
               | 
               | Chinese: Ri Zhao  / Jue Yuan
               | 
               | I guess coincidence
        
               | mananaysiempre wrote:
               | _insolation_ < Latin _sol_ , _solis_ m  "sun"
               | 
               |  _insulation_ < Latin _insula_ , - _ae_ f  "island"
               | (apparently nobody knows where this one comes from)
               | 
               |  _isolation_ < French _isolation_ < Italian _isolare_ <
               | _isola_ < Vulgar Latin * _isula_ < Latin _insula_ , -
               | _ae_ f
               | 
               | Spanish _aislamiento_ < _aislar_ < _isla_ < Vulgar Latin
               | * _isula_ < Latin _insula_ , - _ae_ f
               | 
               | Oh and the English _island_ never had an _s_ sound, but
               | is spelled like that because of confusion with _isle_ ,
               | which is an unrelated borrowing from Old French ( _ile_
               | in modern French, with the diacritic signifying a lost
               | _s_ which was apparently already questionable at the time
               | it was borrowed), ultimately also from Latin _insula_.
        
               | mistercow wrote:
               | > Or after-atmosphere insolation being somewhat on
               | average 1kw/m2.
               | 
               | I'm kind of inclined to say that this one isn't so much
               | of a coincidence as it is another implicit "unit" in the
               | form of a rule of thumb. Peak insolation is so variable
               | that giving a precise value isn't really useful; you're
               | going to be using that in rough calculations anyway, so
               | we might as well have a "unit" which cancels nicely. The
               | only thing that's missing is a catchy name for the
               | derived unit. I propose "solatrons".
        
               | nneonneo wrote:
               | Usefully, the speed of light is extremely close to one
               | foot per nanosecond. This makes reasoning about things
               | like light propagation delays in circuits much easier.
        
               | mistercow wrote:
               | I really wish we had known this back before it was way
               | too late to seriously change our units around. It would
               | mean that our SI length units wouldn't have to have some
               | absolutely ridiculous denominator to derive them from
               | physical constants, and also the term "metric foot" is
               | pretty fun.
        
               | tomjakubowski wrote:
               | Fun, and poetic too
        
               | cozzyd wrote:
               | I use the term "natural foot." It's very useful in
               | simulations.
        
               | kuschku wrote:
               | See, the issue with "foot" is that different people use
               | different body parts to measure length. Germany used the
               | "Elle", which is the distance between wrist and elbow, or
               | roughly one foot. Other regions used the foot or the
               | cubit instead.
               | 
               | The primary advantage of the SI system is that it has
               | only ONE length unit that you add prefixes to.
        
             | euroderf wrote:
             | 32 meters is 35 yards, to within about an eighth of an
             | inch. How's that grab you ?
        
               | GoldenRacer wrote:
               | My favorite is 1 mile = phi kilometers with <1% error
        
               | baliex wrote:
               | That one's useful too. If you know a few Fibonacci
               | numbers you can convert miles to kilometres and vice
               | versa with ease.
               | 
               | 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 ...
               | 
               | 21 km is ~13 miles, 13 km is ~8 miles, etc.
               | 
               | A 26 mile marathon? Must be ~42km.
               | 
               | Same for speed limits too; 34 mph is ~55 kmh
        
               | eesmith wrote:
               | I use that approximation, via the Fibonacci sequence, to
               | translate between miles and km. 13 miles ~ 21 km
               | (actually 20.921470).
               | 
               | My favorite approximation is p*E7 = 31415926.5... , which
               | is a <1% error from the number of seconds in a year.
        
               | saalweachter wrote:
               | 1 km = 5 furlong, with < 1% error.
        
               | mistercow wrote:
               | I wonder if this is related, but imperial measurements
               | with a 5 in the numerator (and a power of two in the
               | denominator) are generally just under a power of two
               | number of millimeters.
               | 
               | The reason is fun, and as far as I know, historically
               | unintentional. To convert from 5/(2^n) inches to mm, we
               | multiply by 25.4 mm/in. So we get 5*25.4/(2^n) mm, or
               | 127/(2^n) mm. This is _just under_ (2^7) /(2^n) mm, which
               | simplifies to 2^(7 - n) mm.
               | 
               | This is actually super handy if you're a maker in North
               | America, and you want to use metric in CAD, but source
               | local hardware. Stock up on 5/16" and 5/8" bolts, and
               | just slap 8 mm and 16 mm holes in your designs, and your
               | bolts will fit with just a little bit of slop.
        
             | dr_dshiv wrote:
             | Alpha brainwaves are almost exactly 10hz, in humans and
             | mice. The typical walking frequency (for humans) is almost
             | exactly 2hz (2 steps per second). And the best selling
             | popular music rhythm is 2hz (120bpm) [1].
             | 
             | Perhaps seconds were originally defined by the duration of
             | a human pace (i.e. 2 steps). These are determined by the
             | oscillations of central pattern generators in the spinal
             | cord. One might suspect that these are further harmonically
             | linked to alpha wave generators. In any case, 120bpm music
             | would resonate and entrain intrinsic walking pattern
             | generators--this resonance appears to make us more likely
             | to move and dance.
             | 
             | Or it's just a coincidence.
             | 
             | [1] https://www.frontiersin.org/journals/neurorobotics/arti
             | cles/...
        
               | jvanderbot wrote:
               | Well, a second is also a pretty good approximate resting
               | heart rate (60 bpm)
        
             | saghm wrote:
             | Reminds me of https://xkcd.com/687/
        
             | panarky wrote:
             | Another bad way to check for non-coincidences is to use a
             | value like g which changes depending on your location.
             | 
             | Pi is the same everywhere in the universe.
             | 
             | g on Earth: 9.8 m/s2
             | 
             | g on Earth's moon: 1.62 m/s2
             | 
             | g on Mars: 3.71 m/s2
             | 
             | g on Jupiter: 24.79 m/s2
             | 
             | g on Pluto: 0.62 m/s2
             | 
             | g on the Sun: 274 m/s2
             | 
             | (Jupiter's estimate for g is at the cloud tops, and the
             | Sun's is for the photosphere, as neither body has a solid
             | surface.)
        
               | TheRealPomax wrote:
               | Fun fact: pi is both the same, and not the same, in all
               | of those places, too.
               | 
               | Because geometry.
               | 
               | If you consider pi to just be a convenient name for a
               | fixed numerical constant based on a particular identity
               | found in Euclidean space, then yes: by definition it's
               | the same everywhere because pi is just an alias for a
               | very specific number.
               | 
               | And that sentence already tells us it's not really a
               | "universal" constant: it's a mathematical constant so
               | it's only constant _given some very particular
               | preconditions_. In this case, it 's only our trusty
               | 3.1415etc given the precondition that we're working in
               | Euclidean space. If someone is doing math based on non-
               | Euclidean spaces they're probably not working with _the
               | same_ pi. In fact, rather than merely being a different
               | value, the pi they 're working with might not even be
               | _constant_ , even if in formulae it cancels out as if it
               | were.
               | 
               | As one of those "I got called by the principal because my
               | kid talked back to the teacher, except my kid was right":
               | draw a circle on a sphere. That circle has a curved
               | diameter that is bigger than if you drew it on a flat
               | sheet of paper. The ratio of the circle circumference to
               | its diameter is less than 3.1415etc, so is that a
               | different pi? You bet it is: that's the pi associated
               | with that particular non-Euclidean, closed 2D plane.
               | 
               | So is pi the same everywhere in the universe? Ehhhhhhhh
               | it depends entirely on who's using it =D
        
               | mr_mitm wrote:
               | In non-euclidean spaces, your definition of pi wouldn't
               | even be a value. It's not well defined because the ratio
               | of circumference to diameter of a circle is dependent on
               | the size of the circle and the curvature inside the
               | circle.
               | 
               | It's probably true that it's only well defined in
               | euclidean space. Your relaxed definition, which I have
               | never seen before, is not very useful.
        
               | _a_a_a_ wrote:
               | I don't agree, I thought what he said was very
               | interesting. It never occurred to me that pi might vary,
               | and over a non-flat space I can see what they're saying.
               | I think it's intrinsically interesting simply because it
               | breaks one of my preconceptions, that pi is a constant.
               | Talking about it being 'not very useful' just seems far
               | too casually dismissive.
        
               | mr_mitm wrote:
               | Pi doesn't vary. The ratio of circumference to diameter
               | of a circle may vary depending on the geometry. Clearly
               | everyone means euclidean space unless specified
               | otherwise. Any other interpretation will only lead to
               | problems, which is why it's not useful. There is really
               | no ambiguity about this in mathematics. Mathematicians
               | still use the pi symbol as a constant when they compute
               | the circumference of a circle in a given geometry as a
               | function of the radius.
        
               | TheRealPomax wrote:
               | There is no "clearly" in Math. The fact that pi is a
               | constant while at the same time not being "the same
               | constant" in all spaces, and not even being "a single
               | value, even if we alias it as the symbol pi" is what
               | makes it a _fun_ fact.
               | 
               | Heaven forbid people learn something about math that
               | extends beyond the obvious, how dare they!
        
               | withinboredom wrote:
               | This whole conversation is painful to read:
               | 
               | 1. Your parent was talking about projections from one
               | space to another and getting it confused.
               | 
               | 2. Pi is pi and their non-Euclidean pi is still pi
               | (unless you want to argue that a circle drawn on the
               | earth's surface has a different value of pi).
               | 
               | The problem comes down to projections, then all bets are
               | off.
        
               | TheRealPomax wrote:
               | Yes. That's what makes it a _fun_ fact. Most people never
               | even learn about non-euclidean math, and this is the kind
               | of  "wow I never even thought about this" that _people
               | should be able to learn about_ in a comment thread.
               | 
               | Calling it painful to read is downright weird. Pi, the
               | constant, has one value, everywhere. So now let's learn
               | about what pi can _also_ be and how _that_ value is not
               | universal.
        
               | travisjungroth wrote:
               | Just sounds like you've confused yourself. It's like
               | spinning in circles and acting like no one else knows
               | which way is up.
               | 
               | That isn't a different pi. That's a different ratio. Your
               | hint is that there are ways to calculate pi besides the
               | ratio of a circle's circumference to its diameter. This
               | constant folks have named pi shows up in situations
               | besides Euclidean space.
        
               | TheRealPomax wrote:
               | Good job, you completely missed the point where I explain
               | that pi, the constant, is a constant. And that "pi, if
               | considered a ratio" (you know, that thing we did to
               | originally discover pi) is _not_ the same as  "pi, the
               | constant".
               | 
               | Language skills matter in Math just as much as they do in
               | regular discourse. Arguably moreso: how you define
               | something determines what you can then do with it, and
               | that applies to everything from whether "parallel lines
               | can cross" (what?) to whether divergent series can be
               | mapped to a single number (what??) to what value the
               | circle circumference ratio is and whether you can call
               | that pi (you can) and whether that makes sense (less so,
               | but still yes in some cases).
        
               | stkdump wrote:
               | My physics prof said g is actually a vector field.
               | Because the acceleration has a direction and both
               | magnitude and direction vary from point to point.
        
               | jvanderbot wrote:
               | Your physics Prof is correct of course, and so is GP.
               | "Standard" values for g exist for these bodies, but it
               | also varies everywhere.
        
               | TheCleric wrote:
               | I volunteer for the Mars mission as a weight loss tool.
        
               | kevindamm wrote:
               | Surviving on Mars will probably involve some mass loss,
               | too.
        
           | KeplerBoy wrote:
           | It does not? Pi has nothing to do with our arbitrary unit
           | system.
        
             | eigenket wrote:
             | pi is always just pi, but g may be defined in terms of the
             | meter.
        
               | KeplerBoy wrote:
               | sure, that's the entire point.
               | 
               | heck, g is not even a constant, it just happens to
               | measure to roughly 9.8 m/s2 at most places around here.
        
             | mikequinlan wrote:
             | Pi is related to the circumference of a circle; the meter
             | was originally defined as a portion of the circumference of
             | the Earth, which can be approximated as a circle.
             | 
             | "The meter was originally defined as one ten-millionth of
             | the distance between the North Pole and the equator, along
             | a line that passes through Paris."
        
               | mistercow wrote:
               | But that connection actually _is_ a coincidence. From
               | what I can tell, when they standardized the meter, they
               | were specifically going for something close to half of a
               | toise, which was the unit defined as two pendulum
               | seconds. So they searched about for something that could
               | be measured repeatably and land on something close to a
               | power of ten multiple of their target unit. The
               | relationship to a circle there doesn't have anything to
               | do with the pi^2 thing.
        
               | mannykannot wrote:
               | It was news to me, but that's what the article says, and
               | it is supported by by Wikipedia, at least. [1]
               | 
               | In addition, I feel the article glosses over the
               | definition of the second. At the time, it was a
               | subdivision of the rotational period of the earth
               | (mostly, with about 1% contribution from the earth's
               | orbital period, resulting in the sidereal and and solar
               | days being slightly different.) Clearly, the Earth's
               | rotational period can (and does) vary independently of
               | the factors (mass and radius) determining the magnitude
               | of g.
               | 
               | The adoption of the current definition of the second in
               | terms of cesium atom transitions looks like a parallel
               | case of finding a standard that could be measured
               | repeatably (with accuracy) and be close to the target
               | unit - though it is, of course, a much more universal
               | measure than is the meridional meter.
               | 
               | [1] https://en.wikipedia.org/wiki/History_of_the_metre
        
               | GuB-42 wrote:
               | Not a coincidence. They defined the meter from the second
               | using the pendulum formula, and the pandulum formula has
               | a pi in it, so pi is going to appear somewhere. The
               | reason there is pi is probably because a pendulum is
               | defined by its length and follows a circular motion that
               | has the length as its radius.
               | 
               | We could imagine removing pi from the pendulum equation,
               | but that would mean putting it back elsewhere, which
               | would be inconvenient.
        
               | mistercow wrote:
               | Right, _that_ connection is not a coincidence. The
               | connection the previous commenter drew between the meter,
               | pi, and the circumference of the earth is a coincidence.
        
               | hanche wrote:
               | > The reason there is pi is probably because a pendulum
               | is defined by its length and follows a circular motion
               | that has the length as its radius.
               | 
               | It's not quite that easy: For small excursions x the
               | equation of motion boils down to x''+(g/L)x=0. There is
               | not a p in sight there! But the solution has the form
               | x=cos([?](g/L)t+ph), with a half period T=p[?](L/g), thus
               | bringing p back in the picture. So indeed not a
               | coincidence.
        
             | mistercow wrote:
             | Can you explain what you're taking issue with in the post,
             | then? Because it specifically lays out how the historical
             | relationship between the meter and the second does in fact
             | involve pi^2 and the force of gravity on earth.
             | 
             | (Granted, from what I can tell, it's waving away a few
             | details. It was the toise which was based on the seconds
             | pendulum, and then the meter was later defined to roughly
             | fit half a toise.)
        
             | nextaccountic wrote:
             | It does, and the formula in the post explains the
             | connection
        
         | blablabla123 wrote:
         | Changing units in Electrodynamics for instance comes with
         | unexpected factors in formulas though, indeed containing p.
         | (CGS <-> SI)
        
           | HPsquared wrote:
           | Isn't that just the change between rad/s and Hz?
        
             | elashri wrote:
             | It is more involving [1]
             | 
             | [1] https://phys.libretexts.org/Bookshelves/Electricity_and
             | _Magn...
        
             | setopt wrote:
             | It's more precisely the difference between "rationalized"
             | and "unrationalized" units.
             | 
             | You need a factor 4pi in either Gauss' law or Coulomb's law
             | (because they are related by the area 4pi*r^2 of a sphere),
             | and different unit systems picked different ones.
             | 
             | It's more akin to how you need a factor 2pi in either the
             | forward or backward Fourier transform and different fields
             | picked different conventions.
        
               | vitus wrote:
               | > It's more akin to how you need a factor 2pi in either
               | the forward or backward Fourier transform and different
               | fields picked different conventions.
               | 
               | Some fields even use the unitary transform -- they split
               | the difference and just throw in a 1/sqrt(2pi) in both
               | directions.
               | 
               | https://en.wikipedia.org/wiki/Fourier_transform#Angular_f
               | req...
        
         | phkahler wrote:
         | Doesn't the relationship hold if we change units? It seems like
         | it must.
         | 
         | When I worked with electric water pumps I loved that power can
         | be easily calculates from electrical, mechanical, and fluid
         | measurements in the same way if you use the right units. Volts
         | _Amps, torque_ rad/sec, pressure*flow_rate all give watts.
        
           | eigenket wrote:
           | Nope, it completely vanishes in other units. If you do all
           | your distance measurements in feet, for example, the value of
           | pi is still about 3.14 but the acceleration due to gravity at
           | the earth's surface is about 32 feet s^(-2). If you do your
           | distance measurements in furlongs and your time measurements
           | in hours then the acceleration due to gravity becomes about
           | 630,000 furlongs per hour squared and pi (of course) doesn't
           | change.
        
             | ValentinA23 wrote:
             | Only because you're using metric seconds instead of
             | "imperial seconds" (the time it takes for a 1 foot long
             | pendulum to complete a full oscillation).
        
               | eigenket wrote:
               | Sure, if you change either of the units you can always
               | change the other one to fix the equation again.
        
               | koolala wrote:
               | But does it work when you use the right Imperial
               | technique?
        
           | usaar333 wrote:
           | No, the equality requires the length of a 2 second period
           | pendulum be g / pi^2. Change your definition of length - that
           | no longer holds true.
           | 
           | g in imperial units is 32 after all. g has units; pi does not
        
             | lupire wrote:
             | A more natural way to say it is that equality requires that
             | the unit of length is the length of an arbitrary pendulum
             | and the unit of time is the half-period of the same
             | pendulum.
             | 
             | The pendulum is a device that relates pi to gravity.
        
               | koolala wrote:
               | Sounds universal. Get a different value on the Moon? Of
               | course... pi squares differently on the moon :)
        
             | phkahler wrote:
             | The equation holds in imperial units as well. The length of
             | the 2 second pendulum needs to be in feet AND the value of
             | g in ft/sec2.
        
               | SAI_Peregrinus wrote:
               | p^2 [?] 32 to you?
        
               | koolala wrote:
               | Replace s in your calculation with imperial s instead of
               | metric s and it isn't imperial feet per metric seconds.
        
               | phkahler wrote:
               | Solving the equation for pi we get:
               | 
               | PI = sqrt(g/L)
               | 
               | g = 9.81. L=1
               | 
               | or
               | 
               | g = 32.174. L=3.174
               | 
               | Either way works to approximately pi. There is a
               | particular length where it works out exactly to pi which
               | is about 3.2 feet, or about 1 meter. My point was that
               | equations like that remain true regardless of units.
               | 
               | The reason pi squared is approximately g is that the L
               | required for a pendulum of 2 seconds period is
               | approximately 1 meter.
        
           | mannykannot wrote:
           | This is not quite the same situation, as you are calculating
           | a value having a dimension (that of power, or energy per
           | second) three different ways using a single consistent system
           | of units, and getting a result demonstrating / conforming to
           | the conservation of energy. If you were to perform one of
           | these calculations in British imperial units (such as from
           | pressure in stones per square hand and rate of flow in slugs
           | per fortnight) you would get a different numerical value (I
           | think!) that nonetheless represents the same power expressed
           | in different units. The article, however, is discussing a
           | dimensionless ratio between a dimensionless constant and a
           | physical measurement that is specific to one particular
           | planet.
        
         | glitchc wrote:
         | Your quibble seems nitpicky and unwarranted. What the author is
         | saying is that the relationship becomes evident if we consider
         | the units of m/s^2 for gravity. They just didn't quite say it
         | like that.
        
           | mistercow wrote:
           | Obviously it's nitpicky. That's what a quibble is. But I
           | don't think it's unwarranted. How you reason your way to a
           | conclusion is at least as important a lesson as the
           | conclusion itself. And in this case, the part I quoted is a
           | bad lesson.
        
         | lupire wrote:
         | The "magic" doesn't disappear in "any" other units.
         | 
         | Period = 2p[?](length/g)
         | 
         | So the "magic" holds in any units where the unit of time is the
         | period of a pendulum with unit length.
        
         | msteffen wrote:
         | It's really the best and only way to find non-coincidences
         | involving the definition of units, though. All such non-
         | coincidences will have this property
        
           | mistercow wrote:
           | All coincidences involving the definition of units will also
           | have this property. Once you've narrowed to that specific
           | domain, invariance to change of units is completely
           | uninformative.
        
           | koolala wrote:
           | Reading this gave me a chill. Please take my temperature and
           | compare it to the norm temperature of humanity.
        
         | arcastroe wrote:
         | I'm surprised at the number of people disagreeing with your
         | quibble. I had the exact same thought as you!
         | 
         | If pi^2 were _exactly_ g, and the "magic" disappeared in
         | different units, THEN we could say "so this is no coincidence"
         | and we could conclude that it has to be related to the units
         | themselves.
         | 
         | But since pi^2 is only roughly equal to g, and the magic
         | disappears in different units, I would likely attribute it to
         | coincidence if I hadn't read the article.
        
           | mjburgess wrote:
           | It would be useful if people carried around some card with
           | all the information that they understood on it, since
           | opinions are largely symptoms of this.
           | 
           | In almost all cases any apparent phenomenon specific to one
           | system of measurement is clearly a coincidence, since reality
           | is definable as that which is independent of measurement.
        
             | twojacobtwo wrote:
             | > since reality is definable as that which is independent
             | of measurement.
             | 
             | In terms of quantum mechanics, would that mean the wave
             | function is real until it collapses due to measurement? Or
             | am I misunderstanding your use of measurement there?
             | 
             | Something about that is sticking in my mind in an odd way,
             | but I can't put my finger on exactly what it is - which is
             | intriguing.
        
               | mjburgess wrote:
               | Measurement can change what is measured, but it doesnt
               | change it from illusion to reality.
               | 
               | I cannot measure santa clause into existence. But I can
               | change the temperature of some water by measuring it with
               | a very hot thermometer.
               | 
               | That measurement changes what is measured is the norm in
               | almost all cases, except in classical physics which
               | describes highly simplified highly controlled
               | experiments. The only 'unusual' thing about QM is its a
               | case in physics where measurement necessarily changes the
               | system, but this is extremely common in every other area.
               | It is more unusual that in classical physics, measurement
               | doesn't change the system.
        
         | john-aj wrote:
         | I agree. But if you remove the "so", there is no contradiction.
         | It is possible the author used "so" not to mean "in other
         | words", but simply as a relatively meaningless discourse
         | marker.
        
           | mistercow wrote:
           | Huh, interesting point. Writing unambiguously is ridiculously
           | hard.
        
             | anon457437 wrote:
             | The comma differentiates. The comma indicates a short pause
             | and a certain intonation in speech (the period means a
             | longer pause and a different intonation). If you say that
             | sentence with and without a pause/comma, you'll see (hear)
             | that the sentence is correct. Reading unambiguously is also
             | hard.
        
               | mistercow wrote:
               | The problem with that is that writers are not consistent
               | with comma usage either, particularly when it comes to
               | informal writing, where prescriptive rules are out the
               | window anyway. And I would argue that it would be a bit
               | of a norm violation even in informal writing to introduce
               | this new point at the end of a paragraph rather than
               | starting a new one, which makes me think that that was
               | not the author's intent.
        
         | gklitz wrote:
         | What? The entire point is that it's no coincidence in this unit
         | set. Saying that changing units indicates a coincidence is like
         | saying that if we see Trump suddenly driving a Tesla after Elon
         | stated throwing money at him, that must be just a coincidence
         | because if we change the car model to a ford then there would
         | be nothing odd about it.
        
           | mistercow wrote:
           | That analogy is so bizarre that I have no idea how to respond
           | to it.
        
             | koolala wrote:
             | Truth feels like a coincidence when 1 small thing can make
             | anything wrong.
        
         | throwawayk7h wrote:
         | you can rule that heuristic out immediately because pi is
         | unitless, surely?
        
         | yunohn wrote:
         | I don't agree with this. You could literally redefine any unit
         | (as we have done so multiple times in the past) and end up with
         | zero coincidences.
         | 
         | All measurement metrics are "fake" - nothing is truly
         | universal, and can easily be correlated with another human made
         | measure eg Pi.
        
           | mistercow wrote:
           | I seriously doubt you could define any system of units that
           | has zero coincidences, even with significant computational
           | effort. Some things in the real world are just going to
           | happen to line up close to round numbers, or important
           | mathematical constants, or powers or roots of mathematical
           | constants, and then you'll have some coincidences.
           | 
           | There are just too many physical quantities we find
           | significant, and too many ways to mix numbers together to
           | make expressions that look notable.
        
         | thayne wrote:
         | Not necessarily. One of the things I was taught when studying
         | astronomy is that if you observe periodicity that is similar to
         | a year or a day, that's probably not a coincidence, you
         | probably failed to account for the earth's orbit or rotation.
        
           | jvanderbot wrote:
           | This is a good example, but actually this is exactly what GP
           | was referring to. It is a coincidence that the thing you're
           | observing is periodic with earth's rotation. Observing a
           | similar thing from a satellite (allegorically the same as
           | "changing bases") would remove the interesting periodicity.
           | 
           | The earths rotation _coincides_ with the phenomenon, so it 's
           | likely a _coincidence_.
        
       | otabdeveloper4 wrote:
       | > was actually proposed back in the 17th century
       | 
       | Pretty sure it was done back in Sumer first.
        
         | karmakurtisaani wrote:
         | A standard free measure for distance? Sounds dubious.
        
           | otabdeveloper4 wrote:
           | No. The other way around. Two seconds is the period of a
           | pendulum with a length of two Sumerian cubits.
           | 
           | (One meter is thus two Sumerian cubits, but that's an
           | artifact due to us still using Sumerian time measurements.)
           | 
           | P.S. I don't know why Sumerians used a factor of two.
           | Americans still divide the day into two 12 hour spans,
           | according to Sumerian fashion.
           | 
           | P.P.S. One second is 1/(2*12*60*60) of a solar day. 12 and 60
           | were "round numbers" in Sumer; they used sexagesimal
           | counting.
        
             | Maken wrote:
             | Probably because 12 is a much better base than 10. 12 can
             | be divided by 2, 3, 4 and 6 and still results in whole
             | numbers, which helps a lot when doing rounding and
             | fraccional numbers. The only reason we use base 10 is
             | because is much easier to count with our fingers.
        
               | jjk166 wrote:
               | There's also a method of counting where you touch your
               | thumb to the sections of your fingers on the same hand,
               | which naturally lends itself to base 12. This can be
               | extended by keeping track of how many times you've
               | counted to 12 on the other hand, which lends itself to
               | either base 60 or base 144.
               | 
               | Interestingly, the Sumerians did not seem to employ this
               | method, they would count 6 instances of counting to 10.
        
             | gavindean90 wrote:
             | Because it traverses the distance twice would be my guess.
             | If you show someone a pendulum going through 3 periods and
             | asked a group of people a generic question like "how many
             | times did it move" without clarifying what you meant I
             | would bet maybe half the people would say 6 as long as
             | everyone counted correctly.
        
         | ValentinA23 wrote:
         | https://www.ukbiblestudents.co.uk/Great%20Pyramid/chapter%20...
         | 
         | >"It was contended," says Dr. Peacock, " by Paucton, in his
         | Metrologie, that the side of the Great Pyramid was the exact
         | 1/500th part of a degree of the meridian, and that the founders
         | of that mighty monument designed it as an imperishable standard
         | of measures of length.
         | 
         | https://www.theguardian.com/science/2020/dec/06/revealed-isa...
         | 
         | >Newton was trying to uncover the unit of measurement used by
         | those constructing the pyramids. He thought it was likely that
         | the ancient Egyptians had been able to measure the Earth and
         | that, by unlocking the cubit of the Great Pyramid, he too would
         | be able to measure the circumference of the Earth.
        
       | BrandoElFollito wrote:
       | As a physicist, this makes sense. Pi = 3, pi^2 = 10, which is g
       | 
       | Not sure why everyone is surprised.
       | 
       | Ah, and a year is pi*10e9 seconds (IIRC)
        
         | exe34 wrote:
         | pi * 1e7
        
         | radiator wrote:
         | As a physicist? When we did physics at school, and we were
         | solving problems, the answer was _always a number together with
         | its unit_. pi2 might be 10 because it is a pure number, but g
         | can never be 10, because it is an acceleration, a physical
         | quantity, so it must be 10 of some unit.
        
           | bmacho wrote:
           | Not if you define g as the real number before m/s^2, in the
           | expression '10 m/s^2'.
           | 
           | In middle school physics lessons this makes teachers to hate
           | you (it's their job to ensure that you do not do this), but
           | after that, this has advantages time to time.
           | 
           | .. I remember hearing an _anecdote_ that ancient Greeks did
           | not know that _numbers can be dimensionless_ , and when they
           | tried to solve cubic equations, they always made sure that
           | they add and substract cubic things. E.g. they didn't do x^3
           | - x, but only things like x^3 - 2*3*x. I don't think this is
           | true (especially since terms can be padded with a bunch of
           | 1s), but maybe it has some truth in it. It is plausible that
           | they thought about numbers different ways than we do now, and
           | they had different soft rules that what they can do with
           | them.
        
           | BrandoElFollito wrote:
           | Oh, come on, it is inches / (day * "hold on"). Everyone knows
           | this, this is physics for art majors 101.
           | 
           | In guess it's a good thing I left physics after my PhD.
        
         | CoastalCoder wrote:
         | I assumed the pi / g connection was because cows that
         | accelerate in a vacuum are _spherical_.
        
           | openrisk wrote:
           | I think it was Gauss who proved that any convex cow would
           | work equally well. But we need to assume an infinitesimally
           | thin and infinitely long tail as boundary condition.
        
           | Sharlin wrote:
           | According to the Banach-Tarski paradox, if you accept the
           | Axiom of Choice, you can disassemble a spherical cow and put
           | the parts back together such that you end up with two cows of
           | the original size. How exactly this affects Cow Economics is
           | not well-understood.
        
         | fouronnes3 wrote:
         | As a computer scientist this is not surprising either. After
         | all there are only three numbers: 0 1 and n.
        
           | 360MustangScope wrote:
           | You mean the legendary "i". There is no n.
        
           | de_nied wrote:
           | Yea if you're some classical snob.
           | 
           | - Posted by the quantum gang
        
           | pansa2 wrote:
           | Remember that `i` is also a number. As in `for i = 0 to n`.
           | 
           | Don't believe those mathematicians when they tell you that
           | `i` is "imaginary".
        
             | Anarch157a wrote:
             | All numbers are imaginary.
             | 
             | sqrt(-1) should have been called w, for "weird".
        
               | syockit wrote:
               | I use w for the complex roots of 1 though, when rewriting
               | FFT notes.
        
           | HPsquared wrote:
           | And int_max
        
             | Maken wrote:
             | That's a implementation detail.
        
           | jeffwass wrote:
           | One of my old physics professors said something similar -
           | there are only three numbers in the world - 0, 1, and
           | infinity. No wait, zero is just one divided by infinity, so
           | there are only two numbers, zero and one. So if the answer is
           | not zero, it must be one. (ie, how to justify dimensional
           | analysis and ignore any dimensionaless constant).
           | 
           | Hysterical, especially for the fact that he quotes 'two' and
           | 'three' in the sentence itself.
        
             | imoverclocked wrote:
             | He already got rid of "three" and just needed a little help
             | to get rid of "two." Since we already have 0 and (almost)
             | everything else can just be "one more" than something else,
             | we only need 0 and one more ... or 1.
             | 
             | One and Done!
        
             | klabb3 wrote:
             | Another one would be philosophy: there's nothing, something
             | and everything. Or logic: [?], ![?] and [?]. Just rambling
             | here, but seems like universal concepts across fields.
        
               | john-aj wrote:
               | Chiming in from theoretical linguistics: it is impossible
               | for natural languages to "count", i.e. make reference to
               | numbers other than 0, 1 or infinity.
               | 
               | As an example, there are languages where prenominal
               | genitives are impossible (0).
               | 
               | Then, there are languages, such as German, where only one
               | prenominal genitive is possible (1):
               | 
               | > Annas Haus
               | 
               | > *Annas Hunds Haus
               | 
               | Finally, there are languages, such as English, where an
               | infinite number of prenominal genitives are possible
               | (infinity).
               | 
               | > Anna's house
               | 
               | > Anna's dog's house
               | 
               | > Anna's mother's dog's house
               | 
               | > Anna's mother's sister's ... dog's house
               | 
               | But there are no languages where only two or three
               | prenominal genitives are possible.
               | 
               | This property is taken to be part of Universal Grammar,
               | i.e. the genetic/biological/mental system that makes
               | human language possible.
        
           | ithkuil wrote:
           | And -0 and NaN
        
         | hyperhello wrote:
         | 3600 seconds per hour, times 3*8 is only about 80,000 seconds a
         | day. You can't get to a billion from there.
        
         | sa46 wrote:
         | Pi seconds is a nano-century. So 1 year = pi*10^7 seconds
        
         | remuskaos wrote:
         | A year is pi 10^7, or pi 1e7.
         | 
         | On the other hand, 10 e9 = 10 * 10^9.
        
         | leoff wrote:
         | as a mechanical engineer, can confirm. also, e [?] pi [?] 3
        
           | winwang wrote:
           | in fact, e = 2, made rather abundantly clear in "finite
           | difference" calculus, and also that in computer science, the
           | "natural" log base 2.
        
         | Sharlin wrote:
         | The pi in pi*10^9 seconds clearly comes from the fact that
         | Earth's orbit is circular.
        
           | maxnoe wrote:
           | Nore sure if serious or not, but anyway:
           | 
           | 1) it isn't circular, although just barely (it's an ellipse)
           | 2) the length of the day is not really related to the length
           | of a year, and the second was defined as 1 / (24 * 60 * 60) =
           | 1 / 86400 of the mean solar day length
           | 
           | So this is really just a coincidence, there is no
           | mathematical or physical reason why this relationship (the
           | year being close to an even power of 10 times pi seconds)
           | would exist.
        
             | Sharlin wrote:
             | Definitely not serious :)
             | 
             | But from the fact that an Earth year happens to be roughly
             | pi*10^7 seconds long, it follows that in 10^7 seconds Earth
             | travels about two radians, or one orbital diameter, and
             | equivalently that the diameter of Earth's orbit is roughly
             | 10^7 seconds times Earth's orbital speed.
        
       | breck wrote:
       | Very interesting!
       | 
       | So if I understand correctly: the meter was defined using gravity
       | and p as inputs (distance a pendulum travels in 1 cycle), so of
       | course g and p would be connected.
        
         | fweimer wrote:
         | On the hand, g is about 32.2 ft/s2. So it's suddenly related to
         | p3? I think there's no connection at all, it's just an
         | accident. It would be really weird if some contemporary
         | property of the earth were actually related to a fundamental
         | mathematical constant. It's similar to finding a message among
         | the digits of p that shouldn't be there, statistically
         | speaking.
        
           | cvoss wrote:
           | The bulk of the article is devoted to explaining that g =
           | pi^2 in m/s^2 units (under an old definition of meter)
           | because (that definition of) the meter was not selected
           | arbitrarily, but selected in a way that makes the equation
           | hold on purpose.
        
       | thaumasiotes wrote:
       | g is related to the radius of the earth; the meter is related to
       | the circumference of the earth; and pi is the relationship
       | between the radius and the circumference.
        
         | mistercow wrote:
         | Aside from the fact that the post already explained what the
         | actual historical connection is, your explanation requires some
         | serious hand-waving about the mass of the Earth and the
         | gravitational constant, neither of which were known when the
         | meter was first defined.
        
           | jjk166 wrote:
           | Reasonably accurate values for both M_earth and G were known
           | at the time the SI meter was defined.
           | 
           | Also it's not too hard to extend this. M_earth is a function
           | of Earth's radius which goes into the definition of the
           | meter. G is a function of earth's orbital period, which goes
           | into the definition of the second. Further our definition of
           | mass is based on the density of water, which is chosen
           | because it is a stable liquid at this particular orbital
           | distance from a star of our sun's mass.
        
             | mistercow wrote:
             | As far as I can tell, the most recent experiment to measure
             | the mass of the Earth by 1790, when they decided on the
             | definition of the meter, was the 1772 Schiehallion
             | experiment, which gave a value 20% below the actual value.
             | So if pi^2 were to somehow fall out of that it would likely
             | be so far off as to be unrecognizable.
             | 
             | But even that doesn't matter, because the mass of the Earth
             | _didn't_ play a direct role in the definition of the meter.
             | If you take out the whole thing about the meter's
             | definition targeting half a toise, then all you have is
             | "related to the circumference of the Earth", and it would
             | be a monumental coincidence if the mass of the earth and
             | gravitational constant just conspired to somehow drop an
             | unadulterated pi^2 out of the math.
        
       | vessenes wrote:
       | Awesome write up and a great surprise in the history of the
       | definition of the meter.
       | 
       | Reading this reminds me a little of mathematicians like Ramanujan
       | who spent a fair amount of time just playing around with random
       | numbers and finding connections, although in this case, I imagine
       | the author knew the history from the beginning.
       | 
       | Anyway, I feel like my math degree sort of killed some of that
       | fun exploration of number relations -- but I did like that kind
       | of weird doodling / making connections as a kid. By the time I
       | was done with the degree, I wanted to think about connections
       | between much more abstract primitives I'd learned, but it seems
       | to me there are still a lot of successful mathematicians that
       | work this way -- noticing some weird connection and then filling
       | out theory as to why, which occasionally at least turns out to be
       | really interesting.
        
       | jds-67 wrote:
       | Sorry to ruin the party, but g is a quite random number, on other
       | planets the corresponding acceleration is different. So p^2~g is
       | a pure coincidence and not relevant. The Newtonian gravitational
       | constant G is a real constant btw.
        
         | gpvos wrote:
         | Have you read the article? The point is that the definition of
         | the metre, which is used in g, originates from the length of a
         | pendulum that swings once per second in the gravity field
         | around Paris. So it is a matter of definitions, and the length
         | of the metre originates from the duration of the second and the
         | Earth's gravity field. The definitions of 1/40.000 of the
         | Earth's circumference or ~1/300.000.000 of a light second came
         | later.
        
           | ccvannorman wrote:
           | My intuitive assumption, then, is that on Mars they would
           | have come up with a _different_ meter such that p2 [?] 10
           | "mars meters" / s2.
           | 
           | Or alternatively stated, that the Mars meter would be much
           | shorter than Earth's meter if they used the same approach to
           | defining it (pendulums and seconds).
        
             | ValentinA23 wrote:
             | A Martian meter defined by martians should relate their
             | average size, the number of fingers they have on their
             | hands and some basic measure of the planet.
             | 
             | I mean, one meter is defined as 1/10^7 of the distance
             | between the equator and the poles which leads to a round
             | number in base 10.
             | 
             | A unit system is not just something that matches objective
             | reality but something that has some cognitive ergonomy.
        
               | michaelrpeskin wrote:
               | > A unit system is not just something that matches
               | objective reality but something that has some cognitive
               | ergonomy.
               | 
               | Beautifully stated!
               | 
               | And that's one reason why I like the US units of
               | measurement better than SI. I mean, the divide-by-ten
               | thing is nice and all. But _within a project_ how often
               | are you converting between units of the same measurement
               | (e.g, meters to centimeters)? You pick the right "size"
               | unit for your work and then tend to stay there. So you
               | don't get much benefit from the easy conversion in
               | practice.
               | 
               | But if you're doing real hands-on work, you often need to
               | divide by 2, 3, 4, and so on. So, for example, having a
               | foot easily divisible by those numbers works well. And
               | even the silly fractional stuff make sense when you're
               | subdividing while working and measuring.
               | 
               | Of course it all finally breaks down when you get to
               | super high precision (and that's probably why machinists
               | go back to thousands of an inch and no longer fractions).
               | 
               | I think there's a little bit of academic snobbery with
               | the SI units (though, it is a good idea for cross-country
               | collaboration), but for everyday hand-on work the US
               | system works really well. I always love the meme: There
               | are two kinds of countries in the world, those who use
               | the metric system and those who've gone to the moon.
               | 
               | I'm an AMO physicist by training and my choice of units
               | are the "Atomic Units" where hbar, mass of the electron,
               | charge of the electron, and permittivity are all 1. That
               | makes writing many of the formulae really simple. Which
               | is what you say: it has cognitive ergonomy (and makes all
               | of the floating point calculations around the same
               | magnitude). Then when we're all done we convert back to
               | SI for reporting.
        
               | bialpio wrote:
               | One example where picking units within a project is still
               | not saving you from cognitive load is e.g. when doing
               | woodworking. Ymmv, but I can add decimals way faster than
               | I can add 7 9/16" + 13 23/32" (numbers picked arbitrarily
               | but close to a precision of 1mm so if you are ok w/ that
               | precision, you don't even need fractions in SI).
        
           | jds-67 wrote:
           | I have to admit I only read half of the article. Even if
           | there is some historical fact there (but it was not mentioned
           | at the beginning of the article), from a physical standpoint
           | this comparison is already dimensionally wrong and also
           | coincidentally only correct if you choose appropriate units.
           | That was the point I was trying to make. There is not
           | anything "deep" here.
        
             | shermantanktop wrote:
             | I'd suggest fully reading the article.
        
             | gpvos wrote:
             | I admit I scanned the article first and wondered what it
             | was all about. The actual argument is not very clearly
             | presented.
        
             | kbelder wrote:
             | How strange.
             | 
             | "I only ran the first half of the program, but it didn't
             | seem to give the correct answer, so it's obviously broken."
             | 
             | "I only read the first half of the proof, but the answer
             | wasn't contained there, so I'm forced to conclude the proof
             | is worthless."
             | 
             | You simply gave up before encountering the mathematical
             | reason the relationship exists, why the units are
             | different, and so on. You just ran with your incorrect
             | initial assumption.
        
               | gpvos wrote:
               | Not strange at all, most people do that most of the time.
        
         | sidpatil wrote:
         | It's not about the values, but the units of measurement. g is
         | in units of meter/second^2. The article discusses the
         | dependency of the meter's original definition on the value of
         | pi.
        
         | beardyw wrote:
         | You are correct but the point is the way the meter is
         | calculated, g in meters per second should come to pi squared.
        
       | dweekly wrote:
       | Link is broken for me?
       | 
       | "[ErrorBoundary]: There was an error: {}"
        
         | roitman wrote:
         | Try refreshing the page
        
       | shubhamjain wrote:
       | What an amazing post! Such an interesting investigation. These
       | kinds of write-ups make me realize how truly far we are from AGI.
       | Sure, it can write amazing code, poems, songs, but can it draw
       | interesting conclusions from first principles? I asked both
       | ChatGPT and Claude, the same question, and both failed at
       | pointing out the connection the author states.
       | 
       | This is not to deride feats of AI today, and I am sure it will
       | transform the world. But until it can show signs of human
       | ingenuity in making unexpected and far-off connections like
       | these, I won't be convinced we are nearing AGI.
        
         | air7 wrote:
         | Arguably most humans can't do this either.
        
         | avaldez_ wrote:
         | > Sure, it can write amazing code, poems, songs, but can it
         | draw interesting conclusions from first principles?
         | 
         | Can _you_?
         | 
         | https://youtu.be/KfAHbm7G2R0?si=oAPrNGylo7pUcRMZ
        
         | badgersnake wrote:
         | The only thing with more bollocks in it than this article is
         | your aibro comment.
        
       | kwhitefoot wrote:
       | It isn't equal to g even in SI units except at some very few
       | spots on the surface of the earth.
       | 
       | Change the units to any other system and it's not even roughly
       | true.
       | 
       | Edit: Now that i have read the article i see that it is no
       | coincidence at all that it is close the pi squared. very
       | interesting.
        
       | philzook wrote:
       | I've got a related one I like. Why are the Avogadro's number and
       | Boltzmann's constant inverses of each other N ~ 1/k? The
       | statement doesn't make sense because the units don't work out,
       | but it is true in mks. It's because they multiply to the gas
       | constant which is ~1. They both are numbers to transfer from the
       | microscopic to human scale units and they cancel for the gas
       | constant, which is about human scale experience of gases.
        
         | bonzini wrote:
         | But it's a coincidence, right? N*k=8.31 is
         | pressure*volume/temperature for a mole of gas. Temperature has
         | a relatively small range (100-1000) and there's no reason why
         | the range of P*V couldn't be far from that range, for example
         | 0.01-0.1, with a different definition of meter, second or
         | kilogram.
        
           | lupire wrote:
           | Meter, second, and kilogram were all chosen to be
           | approximately the scale of a human, and the combined
           | multiplicative units like Pascal, m^3, and Kelvin/Celsius are
           | also numerically 1 in these units.
        
             | Someone wrote:
             | > Meter, second, and kilogram were all chosen to be
             | approximately the scale of a human,
             | 
             | "Approximately the scale of a human" leaves so much wiggle
             | room that I don't see how one can defend that claim.
             | 
             | > and the combined multiplicative units like Pascal
             | 
             | You don't explicitly claim it, but I wouldn't say the
             | Pascal is "Approximately the scale of a human". Atmospheric
             | air pressure is about 105 pascal, human blood pressure
             | about 104 pascal, and humans can very roughly produce about
             | that pressure by blowing.
        
               | Ekaros wrote:
               | Which is why I have always kinda hated kilogram. Such an
               | ugly unit for it having prefix. Grav should have been
               | correct answer, but instead we ended up with something
               | that is too small... That is in reality gram. For grams
               | we could simply have milligravs or decigravs for 100g
               | equivalents... Not that hard considering decilitres are
               | used and decimetres are kinda tried in schools.
        
             | stkdump wrote:
             | A human is ~1 meter, 1e2 kilograms and 1e9 seconds.
        
         | HuangYuSan wrote:
         | Funnily Avogadro's constant is actually equal to 1: it's
         | defined as Avogadro's number times mol, but mol is itself a
         | dimensionless quantity equal to the inverse of Avogadro's
         | number.
        
           | aaaronic wrote:
           | Multiplying by increasingly complicated expressions
           | equivalent to "1" is what I remember doing for almost every
           | problem in Quantum Mechanics.
        
       | sycren wrote:
       | If the definition of the meter is still wrong disallowing p2 = g,
       | how might this affect other calculations like for example thrust
       | and in aerospace engineering?
        
         | kseistrup wrote:
         | And what would all other natural constants look like, had the
         | meter kept the value derived from the length of the pendulum?
        
       | im3w1l wrote:
       | I knew that historically meter was related to the size of the
       | earth somehow, but I had never had about the pendulum definition!
        
       | spacebacon wrote:
       | I laughed 3 times reading this article while pondering the
       | novelty of standardization.
       | 
       | Is standardization the sans-serif of civilization?
        
       | alberth wrote:
       | No mention of 'meter' being the unit of measurement, make this
       | like saying 3:14pm is related to pi.
       | 
       | There's no correlation between a continuous number and a unit of
       | measure. That's truly apples to oranges comparison.
       | 
       | g can easily be expressed in 'feet' as ~32.1 ft/s^2
        
         | mistercow wrote:
         | What do you mean by "no mention"? The entire article is about
         | why this is specifically due to how the meter was first
         | defined.
        
       | ValentinA23 wrote:
       | Okay so this one has an explanation. But what about these ?
       | 
       | https://en.wikipedia.org/wiki/Mathematical_coincidence
       | 
       | See also this blog: https://martouf.ch/tag/coudee-royale-
       | egyptienne/
       | 
       | One french royal cubit [?] one egyptian cubit [?] about p/6
       | meters. One royal span [?] 1/5 meter = 20cm.
       | 
       | I'm wondering whether some of these coincidences could be
       | explained by the anthropic principle, which deals with these
       | quasi-equalities, for instance:
       | 
       | >An excited state of the 12C nucleus exists a little (0.3193 MeV)
       | above the energy level of 8Be + 4He. This is necessary because
       | the ground state of 12C is 7.3367 MeV below the energy of 8Be +
       | 4He; a 8Be nucleus and a 4He nucleus cannot reasonably fuse
       | directly into a ground-state 12C nucleus. However, 8Be and 4He
       | use the kinetic energy of their collision to fuse into the
       | excited 12C (kinetic energy supplies the additional 0.3193 MeV
       | necessary to reach the excited state), which can then transition
       | to its stable ground state. According to one calculation, the
       | energy level of this excited state must be between about 7.3 MeV
       | and 7.9 MeV to produce sufficient carbon for life to exist, and
       | must be further "fine-tuned" to between 7.596 MeV and 7.716 MeV
       | in order to produce the abundant level of 12C observed in nature.
       | 
       | Source: https://en.wikipedia.org/wiki/Triple-
       | alpha_process#Improbabi...
       | 
       | The idea goes like this:
       | 
       | 1. A more fundamental aspect under the anthropic principle which
       | underpins the existence of complex life and intelligent observers
       | is the quasi-alignment of values such as the fundamental
       | constants in physics within a short margin.
       | 
       | 2. If you consider the universe to be the product of a random
       | sampling process over these constants (either real or virtual, it
       | occurred many times or just once), and given the fact we exist,
       | which implies an abundance of coincidences, the maths seem to
       | tell us that we should expect to observe superfluous coincidences
       | that are non-functional for the appearance of complex life,
       | rather than the strictly minimal set of functional coincidences
       | necessary for its emergence.
       | 
       | 3. This implies that coincidences and pattern seeking are not
       | just features (or bugs) of our complex minds but are present in
       | the universe latently since it is not just fine-tuned for the
       | emergence of complex life but for the presence of coincidences
       | such as these https://medium.com/@sahil50/a-large-numbers-
       | coincidence-299c....
       | 
       | 4. It may be even testable by running computer experiments
       | relying on genetic programming/symbolic regression to see whether
       | there is something special about the value of physical constants
       | in our universe when compared to the value they would have in
       | other universes. I think such experiments should factor the fact
       | that not all equations with the same mathematical complexity
       | (number of operands and operators) have the same cognitive
       | complexity. Indeed, if you look at the big equation in the link
       | above, you'll remark that it can be further compressed into a/b =
       | c/d (where a is the photon redshift radius for instance). So I
       | guess you'd also have to throw into the mix Kolmogorov
       | algorithmic complexity to assess this aspect (which is in fact
       | used in some cognitive theories of relevance to tackle this kind
       | of stuff to the tune of "simpler to describe than to generate")
       | 
       | Thoughts ?
        
       | EasyMark wrote:
       | > Sometimes that was even useful. If you needed to buy more
       | cloth, you'd call the tallest person in the village and have them
       | measure the fabric with their cubits.
       | 
       | I highly doubt this bit of strategy would have worked with
       | sellers of said fabric. They may have not had formal measurements
       | but they weren't stupid either.
        
         | kthejoker2 wrote:
         | I find this comment delightfully ironic in a contemporary
         | moment of blatant shrinkflation.
        
       | karmakaze wrote:
       | Might be interesting if were true in Planck units.
       | 
       | But also 2Pi is fundamental, who defines a ratio of something to
       | 2 of something (radius)?
        
         | rvbissell wrote:
         | No, Tau is fundamental. Pi only exists because someone
         | mistakenly thought the formula for circumference involved
         | diameter, when in fact it involves radius. ("Quit factoring a 2
         | out of Tau!" I tell them.)
        
           | mistercow wrote:
           | Eh, you can find plenty of cases where tau is just as awkward
           | as pi is elsewhere. Right off the bat, the area of a circle
           | becomes more awkward with tau, becoming (tau*r^2)/2, and in
           | general, the volume of an n-ball gains weird powers and roots
           | of two in its denominator as n increases if you switch to
           | tau. In general, I don't think you can really claim either
           | one is "more fundamental". It's just a matter of framing.
        
       | julienchastang wrote:
       | Relatedly, I recommend reading "The Measure of All Things" by Ken
       | Alder about the origins of the metric system and the first
       | scientific conference ever. It is a surprisingly gripping read.
       | 
       | https://www.simonandschuster.com/books/The-Measure-of-All-Th...
        
       | karmakaze wrote:
       | Numerologists unite!
        
       | xxmarkuski wrote:
       | I remember in mechanical engineering class we would often use
       | this for exercise sheets. On our calculator we could directly
       | enter p and 2, thus it was equally as fast to entering 10.
        
         | imoverclocked wrote:
         | That's one way of setting up a standard deviation!
        
       | rich_sasha wrote:
       | This is neat, but still something if a coincidence.
       | 
       | It appears the first definition of a metre is in fact around
       | 1/4e10 the circumference of Earth, and the further coincidence is
       | that a 1m mathematical pendulum has a period of almost exactly 2
       | seconds.
       | 
       | So there's still a neat relationship between mass/radius of
       | Earth, its diurnal rotation period and the Babylonian division of
       | it into 86,400 seconds.
        
         | owisd wrote:
         | According to the article the 1/4e10 circumference definition
         | came second
        
           | rich_sasha wrote:
           | Wikipedia says the Earth circumference definition comes from
           | around Copernican times.
           | 
           | Also my reading of TFA is that the pendulum definition was in
           | fact a redefinition that didn't catch on.
        
           | Ekaros wrote:
           | I wonder how many numbers they checked until they arrived on
           | this one. As to me it seems picked as something close enough
           | for committee work.
        
       | textlapse wrote:
       | I wonder if this is how astrology was born. You can draw
       | arbitrary connections between things if you stare at them long
       | enough.
        
       | bravura wrote:
       | Philosophy time:
       | 
       | Does this mean in 400 years it's possible we no longer disagree
       | about how to evaluate things? i.e. we converge on one
       | totalitarian utility function that everyone basically accept
       | answers every possible trolley dilemma?
       | 
       | In 1600, people just took the world as that: measurements are
       | sloppy, and vary culturally and based upon location etc. But we
       | eventually came upon tools and techniques that are broadly
       | accepted as repeatable and standard.
       | 
       | Would this sort of shift be possible? Or desirable?
        
         | kccqzy wrote:
         | Personal preferences continue to exist. I don't see that
         | happening.
        
       | pclmulqdq wrote:
       | More fun arithmetic coincidences:
       | https://en.m.wikipedia.org/wiki/Almost_integer
       | 
       | Some of these are test vectors for math systems.
        
       | fireattack wrote:
       | Totally unrelated to the content, but about the website itself.
       | 
       | The site completely breaks when I visit it. After some
       | investigation, I found out that if I enable Stylus (a CSS
       | injection extension) with any rules (even my global ones), the
       | site becomes unusable. Since it's built using the React
       | framework, it doesn't just glitch; it completely breaks.
       | 
       | After submitting a ticket and getting a quick response from the
       | Stylus dev, it turns out that this website (and any site built
       | with caseme.io) will throw an error and break if it detects any
       | node injected into `<html>`.
       | 
       | [1] https://github.com/openstyles/stylus/issues/1803
        
         | gpvos wrote:
         | I don't currently use Stylus, but it breaks for me too; it
         | looks like CSS isn't applied at all: I get some big logo
         | images, and the text uses standard fonts. Not sure which
         | extension triggers it, probably Dark Reader. I could still read
         | it, so no biggie.
        
       | otterley wrote:
       | This post feels like one of those cork boards with photos and
       | strings connected between them in some prepper's basement, but in
       | blog post form.
        
       | lutusp wrote:
       | Another "wonderful coincidence" is that the conversion between
       | miles and kilometers involves this constant of conversion :
       | kilometers = miles * 1.609344. Let's call 1.609344 the "km"
       | constant.
       | 
       | As it happens, km is very close the the Golden Ratio
       | (sqrt(5)+1)/2 = 1.618033989... (call this "gr"). In fact they
       | only differ by about 1/2 of one percent (100 * (gr/km - 1) =
       | 0.54%)! As the author of the original article says, "If you
       | express this value in any other units, the magic immediately
       | disappears. _So, this is no coincidence_ ... ". Yeah ... wait,
       | what?
       | 
       | Here's another one. Pi (3.141592654...) is nearly equal to 4 /
       | sqrt(gr) (3.144605511...), call the latter number "ap" for
       | "almost pi". This connects pi to the golden ratio, and they
       | differ by only 0.096% (100 * (pi/ap - 1)). Surely this means
       | something -- doesn't it?
       | 
       | Finally, my favorite: 111111111^2 = 12345678987654321. This
       | proves that ... umm ... wait ...
        
         | 29athrowaway wrote:
         | The best is sum(1, 36)
        
         | areyousure wrote:
         | ln(5) ~ 1.6094379 is much closer, differing by about half of a
         | percent of a percent.
        
         | maxnoe wrote:
         | A year is very close to pi * 1e7 seconds, better than half a
         | percent.
        
         | koolala wrote:
         | Do miles connect to feet and feet vs. gravity connect to the
         | Golden ratio? 6 feet is like 2 pi?
        
       | renewiltord wrote:
       | Hence the 2[?]l formula for the pendulum haha
        
       | Ekaros wrote:
       | Underlying idea of whole metric and SI system is the real start
       | point. You want to define some units that you can easily
       | replicate. Time is reasonable enough one, measure and track
       | length of day and then length of second. Now based on this figure
       | out way to come up with replicable definition for distance,
       | pendulum is good enough gravity is constant enough. Thus linking
       | gravity and meter arises.
       | 
       | From here you can define lot of other units like mass and Volt
       | and Ampere... Everything comes from second which is weird, but
       | does make lot of sense.
        
       | notfed wrote:
       | Another wonderful coincidence:
       | 
       | - Speed of light: 299,792,458 m/s
       | 
       | - Great Pyramid of Giza: 29.9792458degN
        
       | frankus wrote:
       | Another interesting coincidence (or perhaps a decades-long dad-
       | joke troll perpetrated by German-speaking scientists) is that 1
       | hertz is roughly equal to the frequency at which a human heart
       | ("Herz" in german, with a nearly indistinguishable pronunciation
       | to "Hertz") beats.
        
         | Ekaros wrote:
         | That seems rather low rate. Regular rate in rest is 60 to 100.
         | Which only lower bound is roughly 1Hz, while upper rate is
         | quite far what I would understand German to understand as
         | roughly.
        
       | nyc111 wrote:
       | g is the distance an earth skimming satellite falls to earth in
       | one second along the tangent. But I don't know how it is related
       | to pi.
        
       | osigurdson wrote:
       | Having pi^2 = g would annoy me a bit as g is fundamentally a
       | measured value. Depending on the required accuracy of the
       | calculation, you can't even use the idealized value.
        
       | kaapipo wrote:
       | If the length of a meter were defined as the length of a seconds
       | pendulum [1], then g would equal exactly p2. From the pendulum
       | equation:
       | 
       | `T = 2p[?](L/g)`
       | 
       | substitute T = 2 s and L = 1 m:
       | 
       | `2 s = 2p[?](1 m / g)`
       | 
       | solve for g:
       | 
       | `g = p2 m/s2`.
       | 
       | This holds up in any strength of gravity, but the length of a
       | meter would be different depending on it.
       | 
       | [1]. This actually was proposed by Talleyrand in 1790. Imagine
       | the world if this were true!
        
         | n4r9 wrote:
         | The article explains that Huygens proposed this in the 17th C,
         | and gives the same derivation :)
        
       | mro_name wrote:
       | > And yet, no matter how you look at it, this can't just be a
       | simple coincidence.
       | 
       | why not?
        
       | tdiff wrote:
       | Regarding "Catholic meter": its definition depends on time
       | measurement. How did they ensure that "seconds" of different
       | clocks were equal?
        
         | umanwizard wrote:
         | The traditional definition of the second before modern
         | timekeeping was 1/86400 of a day. I'm guessing that was precise
         | enough for their purposes.
        
       | quasarj wrote:
       | > this can't just be a simple coincidence.
       | 
       | uhhhhhh yes it can?
        
       | anigbrowl wrote:
       | Can we do the same with 432Hz please
       | 
       | 432: yes it's a super fun and interesting number 432 cycles per
       | second: seconds are not in fact special
        
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