Talk:Base unit of measurement/Archive 1

There was some other talk at talk. All discussion of the page should be on THIS page, not comments or forum or anything of the sort.

I have rewritten this page from scratch, because it was flatly idiotic before. Now it is merely lame. --Jimbo Wales

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Importance in understanding Fundamental Dimensions

It's important to focus on the Fundamental Dimensions used in physics, so we can understand at any given point of any given physics discussion what we are talking about.

Infact, if you add 2 apples to 2 apples you get 4 apples. But if you add 2 apples to 3 oranges... what do you get? Yes, you get 5 fruits, but you will loose the particular aspect of the apple and of the orange that you started with. So let's focus on the fact that usually we deal with 4 fundamental dimensions or units in:


 * Length measure
 * Time measure
 * Mass measure
 * Electric charge measure

... and that we CAN NOT obviously add a Time measurement (say 5 seconds) to a Length measurement (say 1 mile) because it makes ABSOLUTELY NO sense.

(1 sec + 1 mile = ???)

From these 4 dimensions we can talk about the 80% of ALL physics problems existing now or in the future... (Future?? Who knows the future?)

If you want to talk of the other 20% you need to add other 3 dimensions


 * 1) Thermodynamic temperature measure
 * 2) Amount of substance measure
 * 3) Luminous intensity measure

Once we agreed on so... How would you measure ESP ([Extra Sensorial Perceptions]?)? (LOL) :) (So we can talk about 101 % of physics now, say metaphysics)

little guru

1 sec + 1 mile = 186283.397051 miles.

seconds can be converted to miles using the speed of light. Assigning different dimensions to Time and Length is absurd considering Lorentz symmetry. You could just as well choose some arbitrary coordinate system and decide to assign different dimensions to lenghts in the x, y and z directions. Formulas for distances will then contain conversion factors that are no longer dimensionless (like the speed of light). And then you can claim that you cannot add up distances in the x and y direction!

Count Iblis 23:44, 9 August 2005 (UTC)

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Thanx Jimbo, for letting me appear less idiotic.

Very obliged.



little guru

'''I'm not sure about the tone of this article. Doesn't this discussion belong under 'dimensional analysis'?''' The Anome

Hmm, nah, I've added this new page as a link to the physics page under the "Concepts" paragraph. Little guru

Yes, you did that, but the question is whether a link to dimensional analysis (and maybe adding some information to that page) wouldn't have sufficed.

AxelBoldt

'''And whilst we're at it, what about geometric algebra? (See http://www.mrao.cam.ac.uk/~clifford/introduction/intro/intro.html for a discussion).''' The Anome

I worked as a computer science technician in 2 different Electrotechnical labs, and I can assure you that imaginary numbers exist in the calculus of alternate currents. Is this what you were aiming to talk about?

Little guru

'''No, I'm not claming that complex numbers don't exist. I was talking about vector sums between quantities of different dimensions. Of course all of these notations are abstractions - do the natural numbers 'exist' in reality? How 'real' they (and all the other abstractions) are in physical theory has only to do with the falsifiability of their predictions.'''

The Anome

'''I think this material is (or should be covered) on dimensional analysis. Also, the tone is too colloquial here.'''

AxelBoldt

''So what Axelboldt, you don't like having a [small talk]? once every while?''

little guru


 * As a matter of fact, I don't like small talk very much, but that is besides the point. This is an encyclopedia. --AxelBoldt

... and that we CAN NOT obviously add a Time measurement (say 5 seconds) to a Length measurement (say 1 mile) because it makes ABSOLUTELY NO sense.

'''It would make quite lot of sense. In fact, it's quite often being done in physics.'''

5 seconds + 1 mile = 5.0000053681938 seconds = 931412.99 miles.

Taw

Sorry, but i got to disagree with that Taw.


 * Because V=S/t where


 * V = Velocity


 * S = Space


 * t = Time


 * Because 1 mile=1.609 Kilometers


 * Because the speed of light is 300,000,000 km/sec that is 186,451,211 miles per second


 * Because of the fact that a light ray needs 0,000005363 seconds to "run" for a mile (that is 5,36E-6 in exp notation)

What are you adding?

Duh?

5 oranges + 1 apple = 5.0000053681938 oranges = 931412.99 apples

LOL

We could become MILLIONAIRES? at the speed of light in selling fruit! (apples of course)

ROTFL

Q.E.D.

little guru - Article says:
 * A system of Fundamental dimensions is such that every other dimension can be generated from them. Traditionally, the accepted fundamental dimensions are mass, length, time, and temperature, but in principle, other fundamental dimensions could be used

How can you get amperes from kelvins? And I've got this feeling about this whole article... something just seems wrong about it. And could little guru please not clutter this talk page with trash? I feel like going through and deleting all his nonsense... (Excuse the nasty tone, I've had no sleep :-) -- SJK

Surely all this should be dealt with within dimensional analysis, or in a new fundamental units article? I can't see how temperature is a dimension, either. -- The Anome

I think this article is confused on two counts:

Firstly, the article should probably be talking about units, as the Anome suggested. Dimensions is a misleading term, since it has two distinct but related meanings - one might speak of the "dimensions of space", or the "dimensions of measurement".

Secondly, the word "fundamental" is also misleading. It can mean (i) a complete system of units, such as the SI system, or (ii) a natural (minimal) system of units for describing fundamental physics, i.e. the Planck units (see for example http://math.ucr.edu/home/baez/constants.html).

I think the article is going to have to be re-written. Anyone?

-- CYD