# Physics/Astrophysics Questions **URL:** \ **Category:** Factual Questions\ **Created:** [May 23, 2019, 3:23pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411 "2019-05-23T15:23:33Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [May 24, 2019, 12:00am UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/21 "2019-05-24T00:00:38Z")
> [@Just\_Asking\_Questions](#): > > I was being funny, but…imagine a universe where pi is equal to 3. Now THAT would be an interesting universe. The Ragged Astronauts by Bob Shaw ([https://www.amazon.com/dp/B00H6SOKZA/ref=dp-kindle-redirect?\_encoding=UTF8&btkr=1](https://www.amazon.com/dp/B00H6SOKZA/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1)" From one of the reviews "There is one mathematical curiosity: the geometry around the planets is conical in nature, with the value of pi set to equal exactly 3 (one of the mathematicians uses a rolling wooden disk to demonstrate to his brother that its circumference is exactly 3 diameters in length. He muses, “Even when we go to the limits of measurement, the ratio is exactly three. Does that not strike you as astonishing? That and things like the fact that we have twelve fingers make whole areas of calculation absurdly easy. " ---
**Author:** ![Steven\_Estes](https://avatars.discourse-cdn.com/v4/letter/s/94ad74/32.png) [@Steven\_Estes](https://boards.straightdope.com/u/Steven_Estes)\ **Post date:** [May 24, 2019, 7:47am UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/22 "2019-05-24T07:47:05Z")
I realize that our measurement system is arbitrary and we could call the speed of light, say, one flurble. But the question remains: In this measurement system why isn’t the speed of light two flurbles or thre flurbles or 1/2 flurble? ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [May 24, 2019, 7:58am UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/23 "2019-05-24T07:58:23Z")
Because according to all understanding the speed of light cannot vary, so if it is 1 by definition it does not speed up to 2 or slow down to 1/2. Note, actual light traveling through actual materials (not vacuum) can nonetheless be refracted, dispersed, etc. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [May 24, 2019, 10:05am UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/24 "2019-05-24T10:05:48Z")
When I buy a jar of jam, the label says that it weighs 454 grams; years ago the label on my jam jar said that it weighed 1lb. The strange thing is that there is no difference between the two jars. ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [May 24, 2019, 1:03pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/25 "2019-05-24T13:03:51Z")
> [@Steven\_Estes](#): > > I realize that our measurement system is arbitrary and we could call the speed of light, say, one flurble. > But the question remains: In this measurement system why isn’t the speed of light two flurbles or thre flurbles or 1/2 flurble? If I understand the question, this is literally equivalent to asking why the vacuum permettivity is equal to one groon per fathom and why the vacuum permeability is equal to one schnitz per fathom. Eventually you can combine all these fundamental constants in such a way as to cancel out all units and then you get the [Fine Structure Constant](https://en.wikipedia.org/wiki/Fine_structure_constant). The value of the Fine Structure Constant turns out to be roughly 1/137.035999… It is a deep philosophical question why it has that value and if it is in fact even constant (see Wiki article as a starting point). ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [May 24, 2019, 1:14pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/26 "2019-05-24T13:14:32Z")
The great Richard Feynman himself wrote about this question (quote from Wiki article) > [@Richard Feynman](#): > > It has been a mystery ever since it was discovered more than fifty years ago, (…) … Nobody knows. It’s one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man. You might say the “hand of God” wrote that number, and “we don’t know how He pushed his pencil.” ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [May 24, 2019, 1:44pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/27 "2019-05-24T13:44:07Z")
I’m partial to the speed of light being [3.9 x 10-14 petasmoots per femtotribulation.](http://www.greylabyrinth.com/solution/puzzle067) ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [May 24, 2019, 2:03pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/28 "2019-05-24T14:03:15Z")
In my youth, I wandered around with an oscilloscope wondering about glitches in digital circuits. Knowledge that the speed of light was almost exactly 1 foot per nanosecond often came in handy. The figure ‘c = 1 foot per nanosecond’ is off by almost 2%. For greater accuracy, prefer 1802.6175 gigafurlongs per fortnight. ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [May 24, 2019, 3:54pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/29 "2019-05-24T15:54:45Z")
> [@septimus](#): > > In my youth, I wandered around with an oscilloscope wondering about glitches in digital circuits. Knowledge that the speed of light was almost exactly 1 foot per nanosecond often came in handy. > > The figure ‘c = 1 foot per nanosecond’ is off by almost 2%. For greater accuracy, prefer 1802.6175 gigafurlongs per fortnight. I used to have my Geometry students calculate the speed of light in a vacuum in furlongs per fortnight. Got us into a discussion of the arbitrary nature of units of measurement. I never thought to get them to do it in smoots per \, despite showing them the smoot by using Google Earth. :smack: ---
**Author:** ![Buck\_Godot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/buck_godot/32/6573_2.png) [@Buck\_Godot](https://boards.straightdope.com/u/Buck_Godot)\ **Post date:** [May 24, 2019, 4:14pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/30 "2019-05-24T16:14:43Z")
> [@Steven\_Estes](#): > > I realize that our measurement system is arbitrary and we could call the speed of light, say, one flurble. > But the question remains: In this measurement system why isn’t the speed of light two flurbles or thre flurbles or 1/2 flurble? Because then your definition of flurble would be either too short of too long by a factor of two or three. Re-read [Chronos’s explanation](http://boards.straightdope.com/sdmb/showpost.php?p=21659554&postcount=18). From a four-dimensional space-time perspective it makes sense to view space and time on the same unit set. So that the speed of light is 1 foot per foot. Or one second per second. Now one might want to ask why the angle of my car as it travels through time and space has a slope of 1,647,000 as it moves through time a lot faster than it does through space, but that has to do more with my car than with anything involving light. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [May 24, 2019, 6:10pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/31 "2019-05-24T18:10:44Z")
> [@Steven\_Estes](#): > > I realize that our measurement system is arbitrary and we could call the speed of light, say, one flurble. > But the question remains: In this measurement system why isn’t the speed of light two flurbles or thre flurbles or 1/2 flurble? Related to what you’re asking, there’s a real problem that’s at the heart of modern physics and cosmology. But you first need to understand why you haven’t framed the problem in a way that quite makes sense, as people have been trying to explain. If some universal property is measured in arbitrary units, it’s not a well-formed question to just ask why its value isn’t something different as measured in those units. Take a much simpler scenario. Suppose lengths are measured in flurbles. What would happen if all linear dimensions in the entire universe doubled? Would we all now be giants? Presumably not - because our ceilings would be twice as high, everything in our environment would be twice as long. Even our rulers would have doubled in length, so the apparent length of things in flurbles would appear unchanged. We could modify this scenario to say that everything in the universe except the flurble doubled in length. Now everything would be numerically longer in flurbles, but that doesn’t seem fundamentally important, because objects in the universe would still have the same relative length. In fact, the critical aspect of this scenario is what we assume happens to _other_ properties of our hypothetical universe when everything doubles in length. Forces and masses may be a function of area or volume, the square or the cube of length, and we haven’t said what we are assuming about that. Depending on our other assumptions, we might all collapse under our own weight according to the [square-cube law](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law) that forbids the giant ants of 1960s B-movies; or the universe might remain unchanged. So, if some universal constant is measured in arbitrary units, and you want to ask about it taking a different value, it can be a meaningful question, but it’s important to clarify - relative to what? What are you assuming happens to other universal constants in this scenario? What’s important is the _relationship_ between fundamental properties, not their size in arbitrary units. So, the fundamental questions in physics and cosmology that are closely related to what you’re asking are usually framed in terms of **_dimensionless_ physical constants**. > **[Dimensionless physical constant](https://en.wikipedia.org/wiki/Dimensionless_physical_constant)** > > In physics, a dimensionless physical constant is a physical constant that is dimensionless, i.e. a pure number having no units attached and having a numerical value that is independent of whatever system of units may be used. > The concept should not be confused with dimensionless numbers, that are not universally constant, and remain constant only for a particular phenomenon. In aerodynamics for example, if one considers one particular airfoil, the Reynolds number value of the laminar–turbulent t... One kind of dimensionless constant that’s easy to understand is the _ratio_ of the masses of elementary particles. And, as Frankenstein Monster said above, the fundamental dimensionless constant that’s closely related to the speed of light is called the fine structure constant. > **[Fine-structure constant](https://en.wikipedia.org/wiki/Fine-structure_constant)** > > In physics, the fine-structure constant, also known as the Sommerfeld constant, commonly denoted by α (the Greek letter alpha), is a fundamental physical constant which quantifies the strength of the electromagnetic interaction between elementary charged particles. > It is a dimensionless quantity, independent of the system of units used, which is related to the strength of the coupling of an elementary charge e with the electromagnetic field, by the formula 4πε0ħcα = e2. Its numerical value i... And the huge question about why these dimensionless constants take their observed values is called the **fine tuning problem**. That’s a big discussion, but this is a pretty good starting point: [https://plato.stanford.edu/entries/fine-tuning/](https://plato.stanford.edu/entries/fine-tuning/) ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [May 24, 2019, 8:00pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/32 "2019-05-24T20:00:53Z")
Let’s first suppose that a universe with a “different” speed of light would still have, say, a molecule like tritium hydroxide, which can provide a defined distance and time. Let the ratio between that ratio and the speed of light be called C. Given this definition, @ Physicists: What constants would you change to make C 1% bigger (10% smaller? 99% smaller?) than its present value. What, if anything, would happen to the fine structure constant. How big a change could be tolerated before you’d have to shrug “properties of tritium hydroxide have changed so much (due to this new ⅟α FSC), the formulation no longer makes sense.” To get you started, please correct the errors in the following list: α = 137.040 ⇒ unknown α = 137.039 ⇒ changes in the periodic table α = 137.038 ⇒ star cycles differently; supernova less common α = 137.037 ⇒ chemistry not suitable for life α = 137.036003 ⇒ chemistry not suitable for life α = 137.036002 ⇒ narrow window of opportunity for silicon-based life α = 137.036001 ⇒ chemistry no longer suitable for carbon-based life α = 137.036000 ⇒ life forms must adapt to tighter phosphate bonds α = 137.035999 ⇒ our present universe α = 137.035998 ⇒ our present universe, different genetic code α = 137.03599 ⇒ carbon-based life possible α = 137.03598 ⇒ carbon-based life possible α = 137.03597 ⇒ carbon-based life possible α = 137.03596 ⇒ carbon-based life unlikely α = 137.03592 ⇒ carbon-sulfur life α = 137.03590 ⇒ carbon-sulfur life unlikely α = 105.738806 ⇒ life possible in universe with very different chemistry and star cycles. α = 91.7459122 ⇒ life possible in short-lived universe with very different chemistry and star cycles. α \< 75 ⇒ universe too short-lived for interesting life forms to be likely > [@DSYoungEsq](#): > > I used to have my Geometry students calculate the speed of light in a vacuum in furlongs per fortnight… Uh oh. I didn’t check my answer – is 1802.6 gigafurlongs per fortnight correct? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 24, 2019, 8:06pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/33 "2019-05-24T20:06:53Z")
I wouldn’t say that the Fine Structure Constant is “fundamentally related to the speed of light”. I’d say that it’s most closely associated with the charge of the electron. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [May 24, 2019, 8:49pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/34 "2019-05-24T20:49:17Z")
Basically there’s a fundamental distinction to be made. Either the speed of light is infinite or it’s finite. An infinite speed of light causes all sorts of problems, not the least of what happens when a photon “hits” something. Or what does “wavelength” mean in this situation? (It doesn’t.) So you rule that out. So, it’s finite. Then the question, which I interpret to be basically the OP’s is “Why _this_ speed?” Actually just saying “It’s gotta be some speed. So why not this one?” is a good answer at certain levels. But then you may want to get really technical like in properties of the vacuum and all that. But at some point the “this constant implies that this other constant has a certain value” becomes circular. There’s about [20 physical constants](https://en.wikipedia.org/wiki/Physical_constant#Number_of_fundamental_constants) that makes our Universe work. They are just there. Unless someone comes up with a major breakthrough and ties several of them together. ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [May 25, 2019, 3:31am UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/35 "2019-05-25T03:31:07Z")
> [@septimus](#): > > Uh oh. I didn’t check my answer – is 1802.6 gigafurlongs per fortnight correct? Yes, to the level of exactitude you have given. 🙂 ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [May 25, 2019, 5:43am UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/36 "2019-05-25T05:43:41Z")
This question has come up before. My answer goes like this. The universe we live in is 4 dimensional, 3 of length and one of time, and has a curious property, causality travels at the same rate in any direction in these 4 dimensions. Imagine you are standing still (wrt some inertial frame of reference.) Your ability to affect things in the future is constrained to propagate no faster than the speed of causality. Something you do now can only affect things a minute into the future once your action has propagated for one minute. You can’t have something you do now affecting something 10 minutes in the future propagate for only one minute. It can’t reach that future time. Set an alarm clock to ring in a minute’s time. The alarm clock’s state travels into the future a no faster than the maximum rate, and your future self sees the alarm clock ring in one minute. If you want to see what the world looks like in 100 years time, you must wait 100 years. Thus we know that causality propagates at one time unit per time unit, or for use mere Earthlings, one second per second. But what if things moving? How do we measure movement? Speed is distance per unit time. So we need to define a distance metric. As Chronos points out above, it makes no sense to use different units for different dimensions. We don’t measure height in inches and length in centimetres. The most obvious unit of length is the second. The basic unit of length is how far causality can travel in one second. Something is some distance from you. What is the shortest possible time something you do now affect that other object? If that object is 10 length units away from you, there is nothing you can do to have what you do now affect that object in less than 10 time units. Causality only travels at 1 unit per unit. If the object is 10 seconds away, it will take a minimum of 10 seconds to affect it. And you can have a mix of travel in time and in space. If you are travelling at some very fast speed you will discover that you are only able to travel of the speed of causality in the mix of time and spatial dimensions. The apparent speed in each dimension can be worked out with nothing more complex than Pythagoras’ theorem. So how fast is causality? Clearly, in the only sensible units - it is 1. No dimensions, just 1. Given we have defined the time unit to be one second, our unit of length is one causality second. This turns out to be an inconvenient number, being not too far off from the distance to the moon. And we didn’t know the speed of causality until much later than when we needed to measure lengths. (We missed by a few thousand years.) So we invented all manner of length units that were a bit more convenient. Cubits, yards, feet, metres, furlongs, rods, chains, miles, nautical miles, and so on. We could use seconds. As noted earlier, one nanosecond is pretty close to one foot.\* So what about the speed of light. Well, for a host of interesting reasons, it turns out that if you have no mass, you can’t travel in the time dimension, and can only travel in the spatial dimensions. But remember, the universe constrains us so that we can only travel at the speed of causality. If you are not travelling in time, you must be travelling at the speed of causality in space only. So light travels at this speed. And, behold, we measure light to be travelling at the speed of causality in space. And in fundamental units, its speed is 1. If we used feet, its speed would come out at about one billion feet per second. So how do we define our earthly units of measure? Well the metre was 1/10,000,000 of the distance from the pole to the equator on the meridian that runs through Paris. Not a particularly happy definition, and one that needed work. So they made a metal rod with some inscribed marks. Still not great. Now we define it in terms of time. We need a very accurate clock, and that clock is essentially an atomic clock. A Caesium atom emits energy with a very precise period. We define how many periods of a carefully defined description of exactly which energy emission we are using, and use that time period times the speed of causality to define the metre. Since rather conveniently light travels at the speed of causality, and the energy emission we are concerned with is light, we can measure not simply the time period, but count the number of wavelengths. And so we get the metre. So why does the emission from the Caesium atom have this nice property we can measure, and this particular value? Well it is governed by some other laws of nature, and some other physical constants. And a key one of those for these purposes is the fine structure constant. Why does the fine structure constant have the value it does? We have no idea, but as noted above, we should be eternally grateful that it does. - Whilst writing this I had the inspiration to initiate up a Kickstarter project to make a one nanosecond ruler. There are companies that make steel rules that will do custom rulers. (usually just with your company logo on etc) but it is just a matter of defining an etching pattern. A one nanosecond ruler would fit on the same blank as used for a one foot ruler. But rather than inches and fractions, the ruler measures exactly one nanosecond, and is divided in to 10 sub divisions, of 01. nanoseconds each, with further divisions beneath. Close to useless, but makes an important point. Maybe someone has already done this. I would buy one. 😃 ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [May 26, 2019, 8:12pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/37 "2019-05-26T20:12:09Z")
I’m just bumping this because I missed Francis Vaughan’s comment a couple of days ago, and I think his account above is the best answer to what the OP was really about. > [@Chronos](#): > > I wouldn’t say that the Fine Structure Constant is “fundamentally related to the speed of light”. I’d say that it’s most closely associated with the charge of the electron. And on reflection I also think my entire comment above about the relationship to the fine tuning problem was not really on point. Although the speed of light is an input into most formulations of the Fine Structure Constant, that doesn’t imply that it’s correct to think of the magnitude of the speed of light itself as fine tuned for life. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [May 26, 2019, 8:41pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/38 "2019-05-26T20:41:47Z")
> [@Francis\_Vaughan](#): > > - Whilst writing this I had the inspiration to initiate up a Kickstarter project to make a one nanosecond ruler. There are companies that make steel rules that will do custom rulers. (usually just with your company logo on etc) but it is just a matter of defining an etching pattern. A one nanosecond ruler would fit on the same blank as used for a one foot ruler. But rather than inches and fractions, the ruler measures exactly one nanosecond, and is divided in to 10 sub divisions, of 01. nanoseconds each, with further divisions beneath. Close to useless, but makes an important point. Maybe someone has already done this. I would buy one. 😃 This is the closest I’ve been able to find. It’s plastic, not steel, and has no subdivisions, and frankly looks pretty cheesy. [https://www.flinnsci.com/one-nanosecond-bar/ap7785/](https://www.flinnsci.com/one-nanosecond-bar/ap7785/) ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 26, 2019, 8:41pm UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/39 "2019-05-26T20:41:55Z")
> [@Francis\_Vaughan](#): > > - Whilst writing this I had the inspiration to initiate up a Kickstarter project to make a one nanosecond ruler. There are companies that make steel rules that will do custom rulers. (usually just with your company logo on etc) but it is just a matter of defining an etching pattern. A one nanosecond ruler would fit on the same blank as used for a one foot ruler. But rather than inches and fractions, the ruler measures exactly one nanosecond, and is divided in to 10 sub divisions, of 01. nanoseconds each, with further divisions beneath. Close to useless, but makes an important point. Maybe someone has already done this. I would buy one. 😃 Grace Hopper used to hand out nanoseconds to attendees of talks she gave. They were ~ 1-foot sections of wire. I used to have one somewhere. She also had a micrometer, which was a ~ 1000-foot roll of wire . ---
**Author:** ![MarvinKitFox](https://avatars.discourse-cdn.com/v4/letter/m/7ba0ec/32.png) [@MarvinKitFox](https://boards.straightdope.com/u/MarvinKitFox)\ **Post date:** [May 28, 2019, 6:59am UTC](https://boards.straightdope.com/t/physics-astrophysics-questions/834411/40 "2019-05-28T06:59:34Z")
> [@Blue\_Blistering\_Barnacle](#): > > Hate to ask, but… > > How fundamental are pi (and e)? Is there some mathematician somewhere who has considered some alternate spatial geometry where these would be different? > > I’m having difficulty imagining such a thing. Pi has nothing to do with spatial geometry, although spatial geometry does use pi to describe some of its properties. Pi is something a lot more fundamental than the mere layout of space. e is the same property, viewed from a different angle. There is a reason why e^(i\*pi) = -1 [Previous page](https://boards.straightdope.com/t/physics-astrophysics-questions/834411.md?page=1) [Next page](https://boards.straightdope.com/t/physics-astrophysics-questions/834411.md?page=3)