Has any experiment actually measured PI to many places?

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Discussion Overview

The discussion revolves around the question of whether there have been any serious physical experiments to measure the value of Pi, particularly in a laboratory setting. Participants explore the implications of measuring Pi physically versus mathematically, and consider the nature of Pi in relation to geometry and spacetime curvature.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that Pi is a mathematical constant defined as the ratio of a circle's circumference to its diameter, and that it cannot be measured physically in a meaningful way.
  • Others question the validity of measuring Pi physically, suggesting that any physical measurement would only yield a limited number of decimal places compared to the extensive calculations possible with modern computers.
  • A few participants propose that if one were to measure Pi in a curved spacetime, the value might differ, leading to speculative ideas about whether Pi could be 3.0 under certain conditions.
  • Some participants argue that the measurement of Pi is not just about its numerical value but also about how accurately Euclidean geometry describes our universe, suggesting that discrepancies could indicate non-Euclidean properties of space.
  • There are references to mathematical methods for calculating Pi, such as series expansions, which are preferred over physical measurements.
  • One participant humorously suggests alternative values for Pi, indicating a playful exploration of the concept rather than a serious claim.

Areas of Agreement / Disagreement

Participants generally disagree on the feasibility and relevance of physically measuring Pi. While some emphasize the mathematical nature of Pi, others explore the implications of physical measurements in different geometrical contexts. The discussion remains unresolved regarding the validity of measuring Pi in a physical sense.

Contextual Notes

Some participants note that any physical measurement of Pi would be subject to measurement errors and limitations inherent in the experimental setup. The discussion also touches on the implications of curvature in spacetime and how that might affect the value of Pi, although these ideas remain speculative.

squirrlmcduckles
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Ok,
This probably seems a silly question, but has there been any 'serious' attempt to measure Pi PHYSICALLY, like in a lab, using say a light fiber in a circle and one down the radius?
If so, where can I find the results/paper?
Thanks!
 
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Pi is a mathematical constant. It is determined through mathematical means, not through experimental means.
 
squirrlmcduckles said:
Ok,
This probably seems a silly question, but has there been any 'serious' attempt to measure Pi PHYSICALLY, like in a lab, using say a light fiber in a circle and one down the radius?
If so, where can I find the results/paper?
Thanks!
What would be the point? Any physical measurement would be limited to a handful of decimal places only, and π has been calculated to more than 13 trillion decimal places as of 2015.

https://en.wikipedia.org/wiki/Pi
 
squirrlmcduckles: Maybe you are thinking along the following lines: π is defined as the ratio of the circumference of a circle to its diameter. In order to know what that value is, we need to draw a circle and measure the circumference and the diameter, i.e. a physical measurement. But π turns up in many mathematical expressions that can be calculated by computer to high degrees of precision. So we are not dependent on a physical measurement.
 
Well, the reason for the seemingly weird question is this.
Pi represents a measurement of 2d to 1d ratio, if we were in a curved spacetime, say on an apple surface, the value of Pi would be different.

So my real thought is, is Pi actually 3.0, and the .14159 just an effect of the expansion of the universe? i.e local/global spacetime curvature?
 
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squirrlmcduckles said:
Well, the reason for the seemingly weird question is this.
Pi represents a measurement of 2d to 1d ratio, if we were in a curved spacetime, say on an apple surface, the value of Pi would be different.

So my real thought is, is Pi actually 3.0, and the .14159 just an effect of the expansion of the universe? i.e local/global spacetime curvature?
This is nonsense.

The circumference of a circle is a length, a one-dimensional quantity. Pi is not a 2d to 1d ratio.
 
squirrlmcduckles said:
but has there been any 'serious' attempt to measure Pi PHYSICALLY



You shouldn't have put "serious" in scare quotes.
 
squirrlmcduckles said:
So my real thought is, is Pi actually 3.0, and the .14159 just an effect of the expansion of the universe? i.e local/global spacetime curvature?

No. Pi really is 3.14159...
You can mathematically construct a circle in a flat geometry and the ratio of the circumference of the circle to its diameter is exactly pi. Just about any graphing utility on the web will let you do this.
 
squirrlmcduckles said:
So my real thought is, is Pi actually 3.0, and the .14159 just an effect of the expansion of the universe? i.e local/global spacetime curvature?
A circumference to radius ratio of 3.0 would indicate positive curvature. A ratio of PI indicates zero curvature.
 
  • #10
Your thought is very interesting at least to me. However what is being said here by other members that you can calculate the value of pi much better using mathematical methods rather than physical ones, especially nowdays that computer hardware has evolved a lot.

For example it is

##\pi\approx 4 \sum\limits_{n=0}^{k} \frac{(-1)^n}{(2n+1)}##

the higher k you put the better approximation of pi you get.
 
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  • #11
squirrlmcduckles said:
Ok,
This probably seems a silly question, but has there been any 'serious' attempt to measure Pi PHYSICALLY, like in a lab, using say a light fiber in a circle and one down the radius?
If so, where can I find the results/paper?
Thanks!

pi is a mathematical constant, not a physical constant. It is similar to e, the number 42, etc... You do not "verify" them via experiments. You verify/derive them via logical mathematical arguments.

Zz.
 
  • #12
Might be interesting to know how many drops N of Buffon's needle on average one has to make to achieve n correct decimals of π with say .95 certainty.
 
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  • #13
squirrlmcduckles said:
Well, the reason for the seemingly weird question is this.
Pi represents a measurement of 2d to 1d ratio, if we were in a curved spacetime, say on an apple surface, the value of Pi would be different.

So my real thought is, is Pi actually 3.0, and the .14159 just an effect of the expansion of the universe? i.e local/global spacetime curvature?

Or wait, maybe pi is actually 100 and the -96.858 is just an effect of the expansion of the universe? Or maybe pi is 10,000 and etc... Let me guess, my suggestions for pi seem silly but 3 seems reasonable to you?
 
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  • #15
squirrlmcduckles said:
Ok,
This probably seems a silly question, but has there been any 'serious' attempt to measure Pi PHYSICALLY, like in a lab, using say a light fiber in a circle and one down the radius?
If so, where can I find the results/paper?
Thanks!
Pi is by definition the ratio of the radius of a circle to its diameter in Euclidian space, and its value has been calculated to many decimal places (and can always be calculated to more). Thus, the measurement that you're describing is not a measurement of the value of pi - we already know that. It is a measurement of how accurately Euclidian geometry describes the universe we live in; any discrepancy between calculated value of pi and the measured ratio (that cannot be attributed to the inaccuracy of the measurement) indicates that we do not live in a perfectly Euclidian universe.
 
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  • #16
A.T. said:
A circumference to radius ratio of 3.0 would indicate positive curvature. A ratio of PI indicates zero curvature.
Note that such a ratio would not be a constant. It would depend on the radius of the circle. The smaller the circle, the smaller the effect of the region's curvature on the ratio of circumference to diameter. In the limit of increasingly small circles, the ratio is still pi, regardless of whether curvature is positive, negative or zero -- as long as it is not infinite.

Edit: Consider, for instance, circles scribed on the surface of the earth. The length of the equator (circumference) is twice the distance from equator to pole and back (diameter). But a crop circle will have a circumference to diameter ratio pretty close to pi.
 
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  • #17
Nugatory said:
... Thus, the measurement that you're describing is not a measurement of the value of pi - we already know that. It is a measurement of how accurately Euclidian geometry describes the universe we live in; any discrepancy between calculated value of pi and the measured ratio (that cannot be attributed to the inaccuracy of the measurement) indicates that we do not live in a perfectly Euclidian universe.

I think this was the OP's point?

Seems to me, the deviation from Euclidean in any small circle is so small that it would be lost in the measurement errors. So, you'd need to measure a really big circle. Unless you're caught in the grip of a black hole, isn't "our universe" pretty flat? Then a really big circle would be Euclidean so you wouldn't see any deviation.
 
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