## Redefine the metric system

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gmalivuk
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toysbfun wrote:
zenten wrote:
gmalivuk wrote:
evilbeanfiend wrote:why bother pretending that's not how it's defined already?

Because 9,192,631,770 is generally not considered to be a "round number".

Anyone know of the smallest base where it would be?

I don't think there is one. A script could probably confirm this by looking for an answer that's an integer to log x++ 9,192,631,770...or something along those lines.

Well, if we used base 1.2578660587847377050667 or so, that number would be a one followed by 100 zeros...

Or did you mean integer base?
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zenten
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gmalivuk wrote:
toysbfun wrote:
zenten wrote:
gmalivuk wrote:
evilbeanfiend wrote:why bother pretending that's not how it's defined already?

Because 9,192,631,770 is generally not considered to be a "round number".

Anyone know of the smallest base where it would be?

I don't think there is one. A script could probably confirm this by looking for an answer that's an integer to log x++ 9,192,631,770...or something along those lines.

Well, if we used base 1.2578660587847377050667 or so, that number would be a one followed by 100 zeros...

Or did you mean integer base?

Well, if we want an integer base then base 9,192,631,770 would definitely work, as 10 is generally considered a round number. I'm just not sure if there's a smaller integer base, because I can't be bothered to factor the number and whatnot.

gmalivuk
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zenten wrote:Well, if we want an integer base then base 9,192,631,770 would definitely work, as 10 is generally considered a round number. I'm just not sure if there's a smaller integer base, because I can't be bothered to factor the number and whatnot.

In base 3, 7, or 21, that number ends with two zeros. But it's not a positive power of any integer other than itself.
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toysbfun
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Torn Apart By Dingos wrote:
SpitValve wrote:If we chose to all live in self-contained domes, we could ignore the year and go for kilodays instead. Hoorah!
Why stick to the old 24-hour days then? I think a ~30 hour day is more suitable for hunams. Why not make a day a nice, round 10^5 seconds (approx 27.8 hours)?

Because the hormones that govern our wake/sleep periods cycle a little over seven times a week. We're biologically programmed for a 24-hour day. That's why six 28-hour days per week never caught on (yes, people have tried it).

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toysbfun wrote:Because the hormones that govern our wake/sleep periods cycle a little over seven times a week. We're biologically programmed for a 24-hour day. That's why six 28-hour days per week never caught on (yes, people have tried it).

I thought light regulation of wake/sleep is the real kick in the can for that kind of change.

SpitValve
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Torn Apart By Dingos wrote:
SpitValve wrote:If we chose to all live in self-contained domes, we could ignore the year and go for kilodays instead. Hoorah!
Why stick to the old 24-hour days then? I think a ~30 hour day is more suitable for hunams. Why not make a day a nice, round 10^5 seconds (approx 27.8 hours)?

Well, we do have our internal body clocks to think about. Apparently our in-built rhythm is about 24 1/2 hours, but it gets reset by the sun each day.

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SpitValve wrote:Well, we do have our internal body clocks to think about. Apparently our in-built rhythm is about 24 1/2 hours, but it gets reset by the sun each day.

From what I've read, it varies significantly from person to person
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kwan3217
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What would I change? Simple. Make the meter 1/10 as long as it is now, and make a gram the mass of 1 (new) m^3=1(new)liter=1(old)liter of water. Since the mass system isn't really based on water anymore, just say that the kilogram artifact is exactly one new gram.

This of course would propagate through all the electrical units in interesting ways, but my guess is that amps and farads wouldn't be too large to use anymore.

The source of this idea is the old conflict between the centimeter-gram-second and meter-kilogram-second systems. Both of these systems have the oddity that one of the fundamental units has a multiplier in it. My (new)meter-(new)gram-second system doesn't have this problem.
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Firstly, I would redefine the second to be the duration of 9 000 000 000 periods of the radiation corresponding to the two hyperfine levels of the ground state of a caesium-133 atom. (A change of just over 2%)

I would then define a metre to be the distance light travels in 1/300 000 000 of a second.

I would then redefine a kilogram as the mass of 1 cubic metre of protons packed as close together as possible (based on classical values for the mass and diameter of an electron).

All other units should be worked out from that.
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bonder wrote:
skeptical scientist wrote:Why would you want to do that when we have a base 10 number system?

Base 12, having more factors, would be a more convenient base than base 10. Just because we have 10 fingers does not mean that we need to have a base 10 number system: the Babylonians had a base 60 number system.

There are even groups advocating a change to a base 12 number system:
The merits of base twelve are due to the great factorability of the number twelve, the next really useful number being sixty, but this latter number is rather too large to be chosen as an every-day number base. Ten is unsatisfactory because its factors 2 and 5 include the prime 5 which in turn is not as useful as the prime 3 (though one professor of mathematics complained that I was not being really fair to the number 5 when I said this ... ). The dozen, and the dozen dozen, or gross, have shown their usefulness in packing and packaging over many, many years.

Common... misconception? (... just stupid, actually). Their number system was base 5. They used tally marks, much like we do (check it, they're very similar), except that 60 was their 100. Their system wasn't base 60 any more than our system was base 100, or 1000, or any other 10^(n+1) that you can think of. In any case, 10 is a good practical base, 12 is a good mathematic base.
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gmalivuk
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I think the first thing to do would be to actually define the goddamn kilogram. Right now, it's just "defined" as the mass of some standard chunk of metal.

I think there's another thread about Avogadro's Number, which mentions this: Give that an exact definition, and then define the kg so that 12 grams is the exact mass of a mole of Carbon-12.

Or if we care more about the large scale, one kg is that mass which makes G exactly 6673*10^-14 m^3/(kg s^2).
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Nimz
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If we use base eight instead of base ten, 1 day = 30 hours. Although I like the idea of having a 28 hour day and 6 day week (but then, what about sabbath?). The week would be the same length as it is now, and the number of hours per day and the number of days per week would both be perfect numbers!

If we're going to talk about using non-integer bases like pi and e, why not throw 1/alpha ~ 137 into the mix?

Btw, I thought the Babylonian system was a hybrid of base 10 and base 6. They had different symbols for tallying tens and ones. The tallies for 1 and the tallies for 10 would alternate, so their "round" numbers would be 10, 60, 600, 3600, 36000, 216000, etc.

Finally, 9,192,631,770 factors as 2x3x3x5x7x7x47x44351. If you want a 1 followed by zeros, 9,192,631,770 is the smallest base for making a round number out of it. If you want a single digit followed by zeros, there are smaller bases. 103,635 seems to be the smallest base that does that. In this case the single digit would be 88,702 in base ten.
Last edited by Nimz on Thu Aug 16, 2007 10:53 pm UTC, edited 1 time in total.
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Ghona
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Nimz wrote:If we use base eight instead of base ten, 1 day = 30 hours. Although I like the idea of having a 28 hour day and 6 day week (but then, what about sabbath?). The week would be the same length as it is now, and the number of hours per day and the number of days per week would both be perfect numbers

With the problem of not being synched with daylight anymore.
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Quote from the abstract of a seminar that doesn't sound hugely interesting:

The next step in improving the SI is likely to see the biggest change
to the SI since it was introduced in 1875. Several fundamental
constants of nature will be fixed and used as the basis for the new
definitions. In particular, the kilogram, which is currently the only
remaining SI definition to rely on a unique physical artefact, will be
re-defined in terms of either the Planck constant h or the Avogadro
constant NA. The ampere is also likely to change from a classical
physics definition to a quantum one involving defining the charge on the
electron.

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gmalivuk wrote:I think the first thing to do would be to actually define the goddamn kilogram. Right now, it's just "defined" as the mass of some standard chunk of metal.

The CSIRO is developing some perfect silicon spheres to define the kg as a certain number of silicon atoms.
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a_passing_lunatic
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Earlier this year, a bunch of nerds which included me defined the Josh to be a measure the satisfyingness of food or something (there was an argument about the statement 'one muffin is never enough', and whether this was to do with the circularity of the muffin or not), but later we redefined the Josh to be the true measure of everything (one Josh, that is).

It makes calculations much simpler.

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### Re:

Shadowfish wrote:the speed of light would be exactly 3*10^8 m/s. I can't be bothered to remember all of those digits.

Why not call it an even billion, and the metre would be a lot closer to a foot.

gmalivuk wrote:I think the first thing to do would be to actually define the goddamn kilogram. Right now, it's just "defined" as the mass of some standard chunk of metal.

The reason for this is that it's a lot easier to precisely compare two masses than to measure just about any of the properties one might use to define it.

bonder wrote:I'd take a tip from the high energy physicists: redefine so that c = h = h_bar = mu_naught = epsilon_naught = pi = G =1.

High energy physicists actually do things like this (I admit I carried it a bit to the extreme) but then at the end of their calculations, they use dimensional analysis to find out how many c's and h_bar's etc. that they need for the correct answer.

Once, a high energy physics professor was doing a calculation in class and in order to get the right answer in the end said "and we can see through dimensional analysis, we need a 2*pi in here"....

You can't set pi to 1, but you can define some of those constants as being 1/pi or 2pi or something times what it is normally / in other systems

kwan3217 wrote:What would I change? Simple. Make the meter 1/10 as long as it is now, and make a gram the mass of 1 (new) m^3=1(new)liter=1(old)liter of water. Since the mass system isn't really based on water anymore, just say that the kilogram artifact is exactly one new gram.

This of course would propagate through all the electrical units in interesting ways, but my guess is that amps and farads wouldn't be too large to use anymore.

The amp was actually arbitrarily defined to be the size it is now. Your units would actually propagate through quite a lot in interesting ways. If we hold the Amp to be the same value it is now, we have:

Code: Select all

(based on the assumption that all these use the new gram where they used the old kilogram)
Force         0.1  N
Pressure     10    Pa
Energy        0.01 J
Power         0.01 W
Voltage     100    V
Capacitance   0.01 F
Resistance  100    Ohm
Conductance   0.01 S
Magnetic flux 100 Wb

If you made the amp smaller, the volt and ohm would be even bigger, along with the weber (the farad and siemens would be smaller). Though, the amp isn't "too big" - it's too big for microelectronics, but not for, you know, power line engineering, etc.
Last edited by Random832 on Fri Jul 11, 2008 7:57 pm UTC, edited 2 times in total.

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### Re:

Torn Apart By Dingos wrote:
SpitValve wrote:If we chose to all live in self-contained domes, we could ignore the year and go for kilodays instead. Hoorah!
Why stick to the old 24-hour days then? I think a ~30 hour day is more suitable for hunams. Why not make a day a nice, round 10^5 seconds (approx 27.8 hours)?

Because the day and year are based on our relationship with the sun. A lot of what we do is based around the sun. But, there's no basis for hours, minutes and seconds to remain the same. If you want 10^5 seconds in a day, simply shorten the second a bit, and there you are.

Personally, I'm not terribly attached to base 10, and would prefer a power of two. Everything in binary would make it take forever to write anything, but base 8 or 16 would be much more math/science friendly.

Edit: I suppose if we cut off our relationship to the sun, as spitvalve suggested, it would make sense, but I doubt we could cut our sun-dependence so easily.

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### Re: Redefine the metric system

Yeah, amps really aren't too big to use in general, because there are plenty of applications where we want rather a large number of them.

Coulombs and farads, though, are rather large for normal applications. (Can't really change either of them without changing other units though, is the problem.)
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### Re: Redefine the metric system

a bet dr brown's flux capacitor is measured in > whole numbers of farads. the farad has clearly been defined to ease maths for time travellers.
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Shadowfish wrote:the speed of light would be exactly 3*10^8 m/s. I can't be bothered to remember all of those digits.

Very true. We should suggest that to the ISO.

Um... I'd probably redefine a litre to be 1 cubic metre. No sense using a pseudonymous unit that can't be defined using the number 1 of any unit to some power. I'd also try to make the kilogram not based on water, but I don't see how I'd be able to do that (considering any unit based on force is based on the kilogram and metre/second in some way, e.g. 1 N = 1 kg*m2/s2), unless I based it on 83 moles of carbon-12? But that would just be basing it on some other chemical. So water it is.

Noticed something: 1 Pa = 1 N/m2, right? Then, it would be kg/s2, which makes no sense whatsoever.

I'd also redefine the hour, minute, and second. The day would be redefined to either 60 or 100 hours, and would be subdivided into 60 or 100 minutes, which would be further subdivided into 60 or 100 seconds. That way, 1 second is much shorter than we would take it to be. XD

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### Re: Re:

Random832 wrote:If you made the amp smaller, the volt and ohm would be even bigger, along with the weber (the farad and siemens would be smaller). Though, the amp isn't "too big" - it's too big for microelectronics, but not for, you know, power line engineering, etc.

But the A looks just so lonely next to kV and MVA when using the per unit system!

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### Re:

tricky77puzzle wrote:I'd also try to make the kilogram not based on water

The modern kilogram is no more based on water than the modern meter is based on the circumference of Earth.
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### Re: Redefine the metric system

Remember the old card that to within half a percent, pi seconds is a nanocentury?

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### Re: Redefine the metric system

I would make the standard measurement of weight the gram, not the kilogram. It's completely illogical as it is! Anyone know why it's a kilo that's the standard unit and not simply 1 gram?

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### Re: Redefine the metric system

Because we decided that mks makes more sense than cgs (except astronomers, who insist on using smaller units even though they're dealing with much, much bigger numbers).
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tricky77puzzle
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### Re: Re:

gmalivuk wrote:
tricky77puzzle wrote:I'd also try to make the kilogram not based on water

The modern kilogram is no more based on water than the modern meter is based on the circumference of Earth.

Well, not based on that steel object, then. Why not make it based on carbon-12, then? But I think the "litre" idea is good, no?

Because we decided that mks makes more sense than cgs (except astronomers, who insist on using smaller units even though they're dealing with much, much bigger numbers).

Why not use MGS then? Well, I can see why astronomers insist on using smaller units... They have a tool known as "scientific notation" that they abuse to no end.

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