Science questions not worth a thread I: I'm a moron!

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Perfection said:
Well my point is not to belittle your question, but to a certain extent remind that every scientific construct has core values that really don't have theoretical justification, they just are that way. Of course, we might postulate something more fundamental, but that too will have said core values.

But I think I should point out that in the case of the speed of light the question isn't so much why the speed of light is 299,792,458 m/s rather why every other speed is X fraction of the speed of light? The speed of light is the most fundamental speed in the universe.
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Again, I wouldn't mind someone figuring it out and telling us all "Why the speed of light is so". Don't worry, I'm not a speed of light denier :p

And... yes, that is a very interesting question. I would think it would have to do with Mass–energy equivalence... but I suck at science, so I am probably wrong, lol.

peter grimes said:
Are you satisfied with the value of pi? It's the same sort of thing.
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We don't know the value of Pi.

Anyway, all i'm saying is that things taken for granted should be investigated to learn the reasons for what they are, even if it is a fruitless endeavor.
 
Right, you can't have a flat faced solid with less than 4 faces.

http://en.wikipedia.org/wiki/Simplex

EDIT: Whoah at your ninja edit

EDIT2: Not a ninja edit I see. Several posts were made in the meantime.

The Imp said:
We don't know the value of Pi.

Anyway, all i'm saying is that things taken for granted should be investigated to learn the reasons for what they are, even if it is a fruitless endeavor.
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We can calculate it to any accuracy we desire though.

There's also a formula for the digits of pi in hexadecimal.

http://en.wikipedia.org/wiki/Numerical_approximations_of_π#BBP_formula_.28base_16.29
 
Yeah - at that point you might as well say we don't know the value of the square root of 2.

Either way, it doesn't stop us from asking the question, "why is the ratio of the circumference of a circle to its diameter pi?" Why isn't it more than that, or less? What would the universe look like if pi was exactly 3?
 
Wheels would be hexagonal.

EDIT: pi is just the limit of ratio of circumference to diameter of a regular n-gon as n->inf.

It turns up in lots of other limits too (sum of 1/(n*n) -> pi*pi/6 as n-> inf)
 
A circle, not a hexagon :p Circles would still have the property that every point on its circumference is equidistant to its centre.

My point is, if the answer is "it wouldn't work - there is no such universe that satisfies those properties", then why can't we say that about the speed of light? Invoking the anthropic principle or something.
 
I'd say that we do indeed know the value of pi - in fact, there are computations going on right now working it out to further and further accuracy. Just because the number is infinitely long doesn't mean we can't know it.

And like Mise said, even if we couldn't know it past a certain decimal place doesn't mean we can't ask questions about it.

I think in this case, as with the speed of light, the value is intimately tied in with the structure of the universe we find ourselves to be living in. In a different universe, the value might be different. Some people think that these fundamental values can't be anything but what they are, other people think that there are many universes adjacent to ours with different values... I'm not sure which way I lean.
 
As I said, it's just a limit.

Why is lim n->inf (1 + 1/n)^n equal to e?
 
The only reason the limit makes sense is because the circumference of a circle can be bounded by two regular polygons. If we lived in a universe where a circle looked different we might not get that as the limit.
 
I know that ;)

I was just comparing that to pi. Both are limits.

EDIT: Taylor series is sum of n->inf 1/n! (starting with n = 0, 0! = 1)
 
Pi is now days defined as an infinite series too (I forget which).

But to get back to the speed of light question. The point is that the speed of light in a vacuum is constant. The exact number we get depends only on the units we use to measure it. A far more sensible system to use (used a lot in special relativity) is to say that c = 1, and then define the metre as the distance that light travels in one second.
The interesting thing is that c is a constant, its absolute value is of almost total irrelevance. The only thing which matters in a physical sense is its relationship with other constants, say Boltsman's or Plank's. And even then, that doesnt mean all that much because all of the fundamental constants have different units to each other and so are impossible to compare directly.
 
Lord Olleus said:
Pi is now days defined as an infinite series too (I forget which).

But to get back to the speed of light question. The point is that the speed of light in a vacuum is constant. The exact number we get depends only on the units we use to measure it. A far more sensible system to use (used a lot in special relativity) is to say that c = 1, and then define the metre as the distance that light travels in one second.
The interesting thing is that c is a constant, its absolute value is of almost total irrelevance. The only thing which matters in a physical sense is its relationship with other constants, say Boltsman's or Plank's. And even then, that doesnt mean all that much because all of the fundamental constants have different units to each other and so are impossible to compare directly.
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There are unitless constants whose numerical value is meaningful, eg. http://en.wikipedia.org/wiki/Fine-structure_constant
 
Lord Olleus said:
The interesting thing is that c is a constant, its absolute value is of almost total irrelevance.
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Seriously, how can you compare two constants if their value is irrelevant?
 
You can compare their two dimensions, thats pretty much all you can. You can't compare two constants that measure different things while making any sense. Otherwise, you're effectively saying something along the lines of "a meter is bigger/smaller than a kilogram" which is nonsensical.

Any dimensional constant only has a value once you define a unit system. For example to say that c = 3*10^8, you first have to decide on what a meter is and on how long a second is. A lot of the time, it is far easier to be able to ignore the factors of c everywhere so you just say c = 1 and redefine the second accordingly.

Obviously, this breaks down when you consider dimensionless constants, because no matter how you define your units their value is the same. Therefore a strong case can be made that they are the only constants whose value matters.
 
Lord Olleus said:
You can compare their two dimensions, thats pretty much all you can. You can't compare two constants that measure different things while making any sense. Otherwise, you're effectively saying something along the lines of "a meter is bigger/smaller than a kilogram" which is nonsensical.

Any dimensional constant only has a value once you define a unit system. For example to say that c = 3*10^8, you first have to decide on what a meter is and on how long a second is. A lot of the time, it is far easier to be able to ignore the factors of c everywhere so you just say c = 1 and redefine the second accordingly.

Obviously, this breaks down when you consider dimensionless constants, because no matter how you define your units their value is the same. Therefore a strong case can be made that they are the only constants whose value matters.
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Is pi a "dimensionless constant"? If not what is an example of one.
 
Yes pi is dimensionless. It's just the ratio of a circles circumference to diameter, irrespective of units used.
 
Birdjaguar said:
Is pi a "dimensionless constant"? If not what is an example of one.
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Yes, pi is a dimensionless constant. Although it would be very convenient to set pi to 1, or even better to 0.5, there is no way to do it, as pi is the same in any unit system. But pi is a mathematical constant: It can be derived from a few axioms and would be the same in any universe where these axioms apply.

Examples for physical dimensionless constants would be the fine structure constant mentioned by dutchfire (which determines the strength of the electromagnetic force), mass ratios for elementary particles (e.g. electron and proton) or mixing angles in the standard model. These cannot be derived from any axioms (yet) and one could imagine universes where these constants would be different.
 
uppi said:
Yes, pi is a dimensionless constant. Although it would be very convenient to set pi to 1, or even better to 0.5, there is no way to do it, as pi is the same in any unit system. But pi is a mathematical constant: It can be derived from a few axioms and would be the same in any universe where these axioms apply.

Examples for physical dimensionless constants would be the fine structure constant mentioned by dutchfire (which determines the strength of the electromagnetic force), mass ratios for elementary particles (e.g. electron and proton) or mixing angles in the standard model. These cannot be derived from any axioms (yet) and one could imagine universes where these constants would be different.
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Thanks.

Which axioms are "required" to derive pi.
 
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