Whatever happened to Marty? He seemed so interested in this subject......?
Or I could give you a hard time in reverse!
One could be Xth generation white (historically European at some point), South African and move here- and be African-American. Or one could be an Xth generation black American who moves to South Africa (American-South African?) and marries a white European-South-African and their children move back to the USA who are thus both black and white South-African-African-European-African-South-African-American?
I love political correctness, because it gives me the wonderful opportunity to throw out how hypocritical it all is. I harassed someone just a few days ago who said, in the same sentence, "African-American", "Asian-American" and then "White", by asking a return question using the terms "Black", "Yellow" and then "European-American."
Just so just say "a black void" and be done with it
1) What does that mixture of origins make me?
2) If you are traveling at 60Km/H, how long must the rope be to tie the canoe to the jetty, before drinking a liter the water?
Whatever happened to Marty? He seemed so interested in this subject......?I was hoping for a 3rd grade explanation of whether a gram is now based on 1/1000 of a Kilogram as measured on a Kimble balance or is it still defined by the weight of one cc of water @4 degrees Celsius. If there was an answer to that posted already, it flew right over me. If it is still based on the one cc of water formula, I don't see how we've made as much progress as we could have in this new development.
Brian
He is off building that balance...
<snip>
I was hoping for a 3rd grade explanation of whether a gram is now based on 1/1000 of a Kilogram as measured on a Kimble balance or is it still defined by the weight of one cc of water @4 degrees Celsius. If there was an answer to that posted already, it flew right over me. If it is still based on the one cc of water formula, I don't see how we've made as much progress as we could have in this new development.
HA! No, my level of interest isn't that high.
If something weighs # units, or is X units long, or is X degrees temp, or is X bright, etc, but nobody is there to measure it, does it really?
Just don't go putting cats into boxes....
A gram is a man- made amount of a fundamental unit, which is mass. But mass has no actual units so the gram is simply assigned to it by us, as the meter was assigned to the fundamental unit length. Now that two completely 'made up' things cross, the cc and a gram of water, is by design when making these imaginary units in the first place and they are very handy for general calculations but still, none of them are linked to anything fundamental or effectively, "real".
There are seven fundamental units or basic units. All others are derived, compounded (such as MPH which is length divided by time, two fundamental units) or some completely man made 'measurement' that are not fundamental or relatable to anything fundamental. The fundamental units are these:
Length
Mass
Brightness (candela)
Current (ampere)
Temperature
Mole
Time
Then there are the four fundamental forces known and they are:
Electromagnetism
Gravity
The Strong force (atomic level only)
The Weak force (atomic level only)
A cubic centimeter of water is a derived unit, consisting of length X length X length. A volume of water measured in any way NOT based on fundamental units is simply a man made 'unit', created so either 1) we can get a handle on something easily- we buy gasoline in gallons, easy and handy but meaningless in the physics world or 2) some link such as one gram is one cubic centimeter of water at a temperature, which is merely man- made units designed to align volume to mass to length or similar.
The Kibble balance has allowed us to define a kilogram by comparing it directly with a fundamental force, which means that the man- made UNIT of a fundamental measurement can now be defined by another man- made UNIT of a different fundamental force. That plus the fact that we can readily only measure one of them (force, not mass) so we can now quantify mass in the physics world.
Or at least that is how it works in my corner of the universe..... I think. :-)
Brian
Thanks, I think. Well OK, that was very informative.
However I still had to read between the lines to guess that a gram is no longer the weight of 1 cc of water at 4 degrees C, but is now 1/1000 of a kilogram as measured by a Kimble balance. Still a guess however. Since I still haven't built my Kimble balance, I think I'll go get a box of cats to shake up and see if I get better results.
...
Watch out for the 'cat stuff' though, just like the arrow example (if it takes 1/2 of the time for an arrow to travel 1/2 way to its target, and 3/4 of the time for it to get 3/4 of that distance..... then it holds that as the distance can be divided infinitely, so too can the arrow's displacement.... therefore, the arrow will never reach its target. Any arrow, under any circumstances).
...
Now you've gone all calculus on us. I think
"If Achilles is to run from point A to B, he must first travel half the distance, then half again, and so on. Taking the distance from A to B as one, the distance Achilles must travel is the series 1/2 + 1/4 + 1/8...... Because there is an infinity of terms in this series, Achilles can never reach his goal."
The gram was never based on any volume measurement of water.
The gram takes inspiration from the density of water: It’s roughly equal to the mass of 1 cubic centimeter of water held at 4°C.
Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre [1 cm3], and at the temperature of melting ice"[2] (later at 4 °C, the temperature of maximum density of water). However, in a reversal of reference and defined units, a gram is now defined as one thousandth of the SI base unit, the kilogram, or 1×10−3 kg, which itself is now defined by the International Bureau of Weights and Measures, not in terms of grams, but by "the amount of electricity needed to counteract its force"[3]
....is, again, mental masturbation IMO.Agreed. (even though that quote was about something else and not this thread as a whole, it still applies IMO)
OK, I think that is where I made my major mistake. I went back and reread, and they use weathermanperson speak. (I.e. "chance of"; "likelihood of"; "trending towards"; "models show" )
I'm not sure why I started this thread, but at least it got to page three... Agreed. (even though that quote was about something else and not this thread as a whole, it still applies IMO)
OK, I think that is where I made my major mistake. I went back and reread, and they use weathermanperson speak. (I.e. "chance of"; "likelihood of"; "trending towards"; "models show" )
I'm not sure why I started this thread, but at least it got to page three... Agreed. (even though that quote was about something else and not this thread as a whole, it still applies IMO)
Of course any serious discussion of science needs an injection of amusement so I did my best there...... but it seems to have bounced off. Oh well, off to the next discussion.
:-)
Brian