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Assume v. Presume

I've had a brainwave (you might call it something different). In electrical/electronic engineering we have two ways to express the ability of current to flow through a conductor - resistance and conductance. One is the inverse of the other, in as much as r = 1/c.

Suppose we were to define lightness as being the inverse of weight, so something that weighs 10kg has a lightness of 0.1/kg. Now "three times lighter than" makes sense, because three times lighter than 0.1/kg is 0.3/kg, which is 3.33kg (ie a third of 10kg). Something of zero weight will have infinite lightness.
 
The unit of conductance is the Siemen, so perhaps I will propose the unit of lightness as being the Wally (I predict it being popular with super-models).

Wallace said:
I must be being brain washed. BH is starting to make sense!. Nice one BH, even I understand that.
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No, it's late on a Friday night and you've just got back from the pub (or is it me who just got back from the pub?).
 
Black Hole said:
Suppose we were to define lightness as being the inverse of weight,
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As, at present, there is no such unit of lightness and your suggestion of the Wally is brilliant and could change science forever. Nearly as good as E=MC squared. I wish you all the luck in the world trying to convince those who set the SI units for official recognition of the Wally? This would certainly alleviate the problem that 'three times lighter' poses. So presumably the Wally is the inverse of the Kg? As you say, the models will be most inpressed by having a mass of 0.02Wa. I have assumed the abbreviation Wa, as W is already in use.
 
Convince anybody? We'll see how long it is before Google spreads the word!

Search: inverse weight unit
 
"Wa" works for me :thumbsup: , but you can't refer to it as a measure of mass - partly because mass is already defined in kg (note the lower case k) but also because we are discussing lightness as the inverse of weight not mass (weight is the force exerted by a mass in a gravitational field or accelerating frame of reference - which are equivalent under General Relativity). If we were to expand the discussion to cover inertial mass we might have to come up with a unit to express the reluctance of memebers to read the Glossary.

Thus Wa represents a measure of the ease with which one could pick up a super-model in a gravitational environment, not their lack of resistance to movement in the vacuum of outer space.

PS: Well done on your conversion factor 0.02Wa = 1SM, I think that's about right (or perhaps just a smidge low).

PPS: Well done on your correct usage of "assume".
 
Black Hole said:
PS: Well done on your conversion factor 0.02Wa = 1SM, I think that's about right (or perhaps just a smidge low).
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I did my calculation in mixed units. Started off with 8stone x 14 /2.2 =50.909. Round down to 50 then convert to Wallys. But I suppose my rounding down is the equivalent to your 'a smidge low' or should it be a smidge high?
Black Hole said:
PPS: Well done on your correct usage of "assume".
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I do try, considering the title of the topic, and the pedants present, but I thought that I was being a smart ass using 'Mass' not weight and now feel extremely embarrased at my incorrect useage of mass when referring to lightness. Nearly as bad as three times lighter.
 
And I just edited my last post ref smidges to make it wrong:frantic: But I noe see that you were referring to 8st, not my rounding down. Jeez, this is confusing. I used to be able to handle conductance, but am now having problems with Wallys. have you posted on Wiki yet? You could always include the 'citation needed' tag to cover your ass
 
If 'light' is the opposite of 'heavy', it is also the opposite of 'dark'. While there is already a measure of weight, giving rise to an undeniable need for a unit of lightness, as addressed above, there is also already a unit of lightness in the sense of luminance (candella). Clearly, then, a suitable unit of darkness is also required, so that one can correctly quantify a statement like "When I switched to low-energy bulbs, my house was one and a half times darker than it was before." This further raises the question of darkness in the metaphorical sense, for which a separate SI unit would be required in order to allow, e.g. "Series 5 of Trueblood is at least 1.25 times darker than series 4."

It's Saturday. I'm not hung over...
 
Spelling is also important for some! ;)

Substitute 'backside' for 'ass' if you can't use the proper word, although smart backside doesn't sound right. :D
 
I think the inverse unit of darkness could be the oiJ (pronounced "joy", notable for his absence so far), whereas darkness itself would have to be on the BH scale.
 
Trev said:
No R=V/I. And how do we get G from Siemen for conductivity anyway?
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G represents conductance not the units of conductance. If you ask how do we get the symbol G for conductance, it is probably in the same way we get:
I for current, L for inductance, Y for admittance, Z for Impedance... :)
 
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