# Measurement systems

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1. Feb 28, 2015

### Lobos

Does anyone know of a good website or book that provides every measurement system that is still being used to this day? For example, I want to know the "how and what" when it comes to measuring cells, atoms, subatomic particles, etc,.

And another question, does anyone know if there is only one measurement system that can be used for everything of the known universe? One system that can measure things from the really big, to the really small.

2. Feb 28, 2015

### Staff: Mentor

3. Feb 28, 2015

### Simon Bridge

Welcome to PF.
What you are asking for does not exist. Every possible system for measuring anything? No.
You will have to be content with looking up how to measure particular classes of things as you need the information.

Similarly there us no one method that will measure everything ... perhaps if you were more specific about what you mean by a measuring system? I suspect you dont just mean a system of units...

In a way... a standard meter ruler can be used to measure any length you name, just tgat some of the lengths will be less accurate than others.

4. Mar 1, 2015

### Lobos

Thanks for the information.

And I'd be happy to be corrected if I'm not using the right wording or just plain incorrect with my approach.

Is it practical to suggest that units of one measurement system could possibly represent the measurement of things not only at the macro level, but represent particles with and without mass? Or is it best to create multiple units of measure to prevent over-simplification/misrepresentation?

In short, what would be better, a universal unit of measure or a bunch of different units of measure?

5. Mar 1, 2015

### Simon Bridge

I think you need to spell out what you mean by "measurement system".

You now appear to be asking about a system of units ... like whether you use kg-m-s or ft-lb-s or something else.
It this correct?

Standard systems of units will have three dimensions - typically "length", "mass" and "time" ... the most widely used being the metric system.
This system can be used to represent quantities at any scale.
Perhaps if you were to say what you find deficient about the metric system, we will be able to better answer your question.

In the search for the "best" system of units, scientists prefer to use "natural" or "unified" units. These are units kinda suggested by Nature.
There are several systems depending on what you are emphasizing - they tend to define units in terms of Universal constants, like the invariant speed (speed of light in a vacuum).

The scale of the units, in any system, is otherwise chosen to be convenient to the subject (avoids writing out lots of zeros).
So while it is possible to write out the size of an atomic nucleus in miles (6x10-19mi) that tends to be inconvenient for calculations.
There is no one system of units that is convenient for all scales.

6. Mar 1, 2015

### Lobos

Again, correct me if I'm wrong, as I have just begun researching into this.

I don't know if there is anything wrong with the metric system, though my wording probably made it seem I believed that, and I apologize. Multiple questions were presented by me along with a disclaimer for anyone to point out flaws with my approach.

Someone informed me about the International System of Units, so I think that's what I was looking for.

Thanks for the help Mr. Bridge. (I gave you a 'like')

7. Mar 1, 2015

8. Mar 1, 2015

### Simon Bridge

It is good to be liked.
I have, as requested, pointed out flaws in your approach - vis: you have not been clear about what you want.
For some reason you are reluctant to follow suggestions to become more clear but it may be that you can use what has been supplied anyway.

You must have been using a system of units before now - why not use that one? Why seek another?
If we understand the motivation for the question it helps us to answer the question.