# Thread: Pi is out! Tau is in!

1. Originally Posted by Spectral
I'm confused by this; could you elaborate? I only went up through Physical Chemistry (well, that was my most difficult math applying class anyway), but I feel like I was pretty much always taught to check and make sure that the units come up right in the end, as if they didn't, something was wrong somewhere. This is really long ago though, I might be misremembering order of operations.[COLOR="red"]
Simple example: Speed = distance / time. Speed = 100 (m)/14 (s) = 100/14 (m/s) = 7.1429 (m/s). Units and math are two separate entities. You can easily divide meters by seconds.
Now let's see: Speed == 10 (m) / 10 (s). But we need to get the distance in 100 seconds = 100(s) * 10(m) / 10(s). We can get rid of 10s = 100. We know the units - meters. If we do not know units - we can get them by doing this: s * m / s = m

2. HERESY! death to Tau xenos filth!

3. Originally Posted by Hurax
What is more fundamental though, the diameter or the radius?
Diameter ... assuming you don't know Pi, then the only way to the radius is either by measuring half the diameter, which would generally done by finding the intersection point of two diameters.

4. Originally Posted by Hurax
Agree with you there. Dropping units in solving something is lazy, you don't save much time but risk making mistakes that you would easily avoid with them.
If you know that the result is in Newtons (for instance) - you do not need to worry about units in the formula. The only thing you have to worry about is that all units are of the same magnitude - so if you have meters in upper part - the lower part should have meters too - not millimeters or something.

5. Originally Posted by ag666
Simple example: Speed = distance / time. Speed = 100 (m)/14 (s) = 100/14 (m/s) = 7.1429 (m/s). Units and math are two separate entities. You can easily divide meters by seconds.
Now let's see: Speed == 10 (m) / 10 (s). But we need to get the distance in 100 seconds = 100(s) * 10(m) / 10(s). We can get rid of 10s = 100. We know the units - meters. If we do not know units - we can get them by doing this: s * m / s = m
Ah, I see what you're saying. Yeah, I think I just expressed the same thing differently. Perhaps I'm still whiffing though.

6. Originally Posted by Spectral
I suppose that's conceptually useful, but it just seems confusing to me. I think I'm better at tracking new information than most folks, but it still just seems intuitive to me to teach both up front, then just use one during learning stages. Sort of a, "oh, by the way, I should mention that tau is also used, but don't worry about that too much for now, we'll come back to that later". I personally like having that sort of thing so that when it comes up later, I don't feel like, "why didn't anyone mention this to me?".
Right. We didn't start dropping the constants until 3rd year physics at University. When you're working out a problem that takes 10+ pages of scratch work before you get it, the pen strokes saved are huge...

7. Originally Posted by ag666
If you know that the result is in Newtons - you do not need to worry about units in the formula. The only thing you have to worry about is that all units are of the same magnitude - so if you have meters in upper part - the lower part should have meters too - not millimeters or something.
I think he and I are thinking of complex equations where the units can get really esoteric and weird. It starts to get pretty important to track them closely at every step. I see what you're saying about them being separate from the math though.

8. Would it really make a difference? I would think it would be an equivalent of using kelvin instead of celsius or etc. It would get you the same result, in some ways the math would be easier in other it could be longer. If you like tau go for it, no ones stopping you, but I don't see a real advantage over the other.

9. Originally Posted by apepi
Would it really make a difference? I would think it would be an equivalent of using kelvin instead of celsius or etc.
Actually - the difference between K and C would be WAY bigger than between Pi and Tau.

At least with Pi and Tau, multiplying by two means the same thing

With C - 40C isn't twice as hot as 20C, matter of fact it is pretty much meaningless what 40C/20C is.

10. To me the argument is as simple as this. Can we stop using pie? Only if we start using tau/2.

Tau/2 is just as bad as 2pie. You can argue about which is more common if you like, but that seems futile.

Wanting the conceptual fundamentals of the constant to be a single units is nice, but how many of the constants are? And it still doesn't change the actual number or the math, only the conceptualization of that number.

As far as teaching kids... fractions were always more hated then multipliers. You don't start teaching kids 2pie. 2pie doesn't come up until(correct me if I'm wrong) maybe grade 12 trig/physics? So your going to either start kids on tau/2 or start with pie and shift them 1/2 way in their mathematics understanding.

11. Originally Posted by apepi
Would it really make a difference? I would think it would be an equivalent of using kelvin instead of celsius or etc. It would get you the same result, in some ways the math would be easier in other it could be longer. If you like tau go for it, no ones stopping you, but I don't see a real advantage over the other.
Actually gas law formula problems with not work with celsius at all, you need to convert :P

12. I stand corrected. This amazing advance simplifies everything.

just becomes h/tau!!!!

13. Originally Posted by schwarzkopf
With C - 40C isn't twice as hot as 20C, matter of fact it is pretty much meaningless what 40C/20C is.
Indeed, Celsius (and Fahrenheit to an even greater extent) are scales of convenience for commonly dealt with everyday temperatures. They're quite useless if we're trying to deal down to "real" heat.

14. Originally Posted by belfpala
I stand corrected. This amazing advance simplifies everything.

just becomes h/tau!!!!
I don't think my calculator has a t button. So I'd have to enter h/2pi anyway.

15. Delicious Xeno Mathemathics!

*snip*

Infracted

16. Originally Posted by Butler Log
I don't think my calculator has a t button. So I'd have to enter h/2pi anyway.
Time to write a nasty letter to Texas Instruments.

17. Originally Posted by belfpala
Time to write a nasty letter to Texas Instruments.
I'm not buying a new calculator just so I can type t/2 when I need to use pi. And my calculator is a Casio.

18. Originally Posted by Butler Log
And my calculator is a Casio.
Well that's your problem right there... (kidding).

Anyway, tau is used for enough things. Torque, time (when t might be confused with temperature), among other things. Tau is fine. Don't give it more work to do. Pi only has one job.

19. Originally Posted by belfpala
Well that's your problem right there... (kidding).
Originally Posted by Butler Log
And my calculator is a Casio.
I'm not kidding! TI-92 represent!

20. Originally Posted by Spectral
I'm not kidding! TI-92 represent!

You don't have a tau button either

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