When the topic of measurement is discussed, many ask, “Why it is important, or, why bother about measurement?”
Most scientists think the answer is obvious (to them it is) and they often quote Lord Kelvin, the 19th century British scientist who”invented” Absolute Zero (among other things) to prove their point:
“I often say that when you can measure what you are speaking about and express it in numbers you know something about it; but when you cannot express it in numbers your knowledge is a meagre and unsatisfactory kind: it may be the beginning of knowledge but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.”
The average person sometimes has difficulty relating to the scientist’s view. It can be done…….. with a little extra explanation.
Here’s my explanation.
Measurements and measurement devices are important to more than just scientists and engineers. They impact everyone’s life; impact them in significant ways and impact them all the time. They affect you and I directly.
How about the bills you pay for items that are metered to you? Electrical power, water, natural gas or oil or propane and the time you spend, literally, on the telephone are charged according to some measuring device.
Do you want it to be a device that has an error favoring the supplier? Hardly.
What about the weigh scales that are used in the grocery store? Same thing. We need accurate measuring devices for fairness in buying almost all goods and services somewhere along the line.
Think about it! Measurements and measurement devices are like Rocky The (Cartoon) Flying Squirrel.
They’re everywhere, everywhere.
The situation is similar in exchanges of goods and services between companies where, for instance, a financial institution lends money to a company and the loan is secured by a mortgage on some property, say fuel oil in a tank farm.
Don’t you believe that both parties in such a transaction depend upon reliable and accurate measuring devices to attest to the correctness of the volume involved?
In manufacturing, the temperature of a process, the flow rate of fuel, the speed of a production conveyor can all be measured and controlled to correctly produce a product that a customer will willingly buy at a competitive price. Scrap dealers buy the mistakes, at reduced prices (and lower profits to the maker, lest the shareholders forget).
Similar issues exist in science and industry and in nearly all aspects of life for measurements of all kinds.
From the temperature of a sick child to the weight of a space vehicle, there are measurement devices used to find the amount or value of one or more properties, or attributes, of specific objects to within an acceptable error.
Whether you care to be involved with measurement or not, you are!
The sooner you understand something about measurement and measurement devices that affect you, your health, your money, your services, your job etc. the sooner you can expect to understand the impact they have in all aspects of your life. When you reach that stage, you may be surprised to find that you can impact some of the measurements and their influence upon your life and/or livelihood.
Measurements are Quantitative, not Qualitative.
(Like a rose is a 3″ red rose not a 1lb lumpy, orange or a 52 gram purple turnip!) According to Lord Kelvin (and most scientists and engineers), measurement is the way we gain substantive knowledge about things. We get numbers.
This is more than the philosophical “knowing” of something to gain knowledge.
The type of knowledge needed by scientists and engineers in order to understand things and how they interact with each other is called quantitative knowledge, or, knowledge that is expressed in terms of numerical values and units. (Kelvin knew about units, too; they’re not in his famous quote, but they probably should be!)
That’s going another philosophical step further from the qualitative to the quantitative. For example, if you needed information about some object, like: how big it is, how much it weighs, what it is made of, what its dielectric constant is, what its temperature is, how much it will heat up if placed in an alternating magnetic field of a given amplitude and frequency, what its color is, how fast it is moving, where is is now and will be in an hour or a microsecond, and so on.
The fact that an object is a sphere takes on a different perspective when it is described as a sphere with a radius of 6 millimeters (about 1/4″-like a marble) or 6 meters (about 18 feet-like a pressurized gas storage tank).
NOTE: If you think these examples have errors in them, recall the difference between a radius and a diameter! You know things better when you know about something quantitative about them. Your knowledge becomes “non-meagre”; it has descriptive attributes.
Numbers and attributes are, however, by themselves not enough. Measurement results are always expressed in terms of units or the ratio of properties or attributes having the same units.
There is a big difference between a journey of 2 meters and 2 kilometers. A journey of 2 (unspecified) is meaningless without knowing what the 2 means!
The Earth has approximately six times more mass than its moon. That means you can know the mass of one if you know the mass of the other of them. The units are ones of mass (not weight-that’s a different property than mass).
Units are tied to all measurements. Without measurement units, the measurements themselves are not worth performing.
The metric or SI system of units (Meters, Kilograms, Seconds, Celsius, etc.) is the common, defined vocabulary for units in most scientific and International Trade matters.
They are not exclusive and there are many unique measurement systems of units in the world. It is most interesting to note that in the USA, the English system of units (e.g. Feet, Pounds, Seconds, Fahrenheit, etc) is still dominant in every day US life and many manufacturing industries, while the English themselves converted to SI or metric units more than 25 years ago. Even the Canadians have changed!