What do we mean by second, meter....? A peek into the world of measurement

Last semester, I took a very interesting subject, Electrical Measurement. And Alhamdulillah, I was taught by a very strict lecturer who was very particular and cared for her students. Thank you Miss Anis Diyana for that. Basically the subject deals with statistical analysis, how the measurement is acquired, how we calculate and deal with errors, the mechanism of the measuring instrument itself, to its errors and sensitivities. Simply put, a very technical subject full with lengthy calculations and mechanism explanations.

One of the many things that popped in my head while dealing with this subject is to wonder how accurate and precise our measurement is. The thought was induced because what I learned was how to calculate errors, not only one layer but layer upon layer upon layer of errors. If I could describe it simply, it is like there is a boundary between the outside world and our measurement. What we measure isn't what exactly 'out' there. There will always be a slight deviation in term of its real value and the measured value - perhaps technology one day might close the gap who knows. Nevertheless, my true purpose of posting this is not to bring you along in my convoluted, complex unneccessary questions and thoughts, but to share with you what I love to share. Knowledge! :)

Have you ever wondered about all the units we use in our daily life, on what are they based upon? Units of measurement like second or meter. When we say, 'I'll be there in five minutes!' or 'Boss, 2 kilos brown beras please..', have you thought about it? Did the question 'How the whole world came to an agreement of what a second is or a kilogram is?' ever pop up in your head? Malaysian kilogram shouldn't be no different than the US' kilogram right? (Actually there is, very-very minute difference.. I'll explain later).


So what do we mean by second, meter......?


There are seven base units of SI(International System of Units) unit, namely second for time, meter for length, kelvin for temperature, kilogram for weight, candela for luminous intensity, ampere for current, and mole for amount of substance. And the whole world uses these units to indicate, measure, monitor and define. For us public, defining these units is not a thing to be concerned of. For example, when we came late to class, our lecturer said "Stop, stand right there. You are one minute late." And then we said "But my one minute is different than yours. I'm just following my standard, you can't punish me for that." Exaggerated. Point taken right? But, in big laboratories, institutional research lab, giant factories, and standard maintenance it's something very important. 

Before we go into the definitions of these units, we should know who's setting the standards for these units. There are three important organizations that are responsible for maintaining the standards, one of them is International Bureau of Weights and Measures. This organization along with the other two work hand in hand internationally to maintain and revise the standard definition for the SI units. They meet once in a few years with their delegates to discuss things regarding the standards. The bureau has another important role which is to maintain accurate worldwide time. A bit WOW isn't it? The reference is called the Coordinated Universal Time(UTC), somehow has the same function as often-used GMT(Greenwich Mean Time). UTC is more carefully calculated and defined, and it is governed by scientific community.

And the bureau also keeps the international prototype of kilogram. This prototype is very carefully protected and secured. Of course, it sets the defining kilogram for the whole world!

One thing you should know that these guys in the organizations are aiming to set the standard based on constants, not physical thing which will change in time. Constants like speed of light or charge of electron.


So what do we REALLY mean by second, meter....?

Ok. We'll go through one by one. As you read, you'll realize that these definitions do depend on one another.

1. Meter - The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second. You might also realize that if you rearrange this definition, it's the speed of light!

2. Second - The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. Previously, they defined a second as 1/(24 x 60 x 60) of the day. It's obvious right why they revise the definition?

3. Kilogram - Previously, it was defined as the mass of one litre of water. Now, it is the unit of mass; it is equal to the mass of the international prototype of the kilogram. What is the international prototype? Click

4. Ampere - The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length. Got it? If you don't understand, just know that when current flows through a conductor, it generates a field(circular most of the time).  When two magnetic fields meet, they are either pushed or pulled.

5. Kelvin - The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. Emm..what is triple point then? Interestingly, triple point is the temperature and pressure at which a substance coexists as all three phases of matter; gas, liquid, solid. Simply, it's a condition where for example H2O will exist as ice, water, and gas at the same time.

6. Mole - 1. The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is "mol."  2. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.

7. Candela - The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian. Don't worry, I don't understand it well myself. Self-effort please haha..

The definitions I listed are the exact definitions. Not a word changed.

Ongoing revision..
I don't know about other units, but from what I know, kilogram is going to be revised again and the process of introducing the new more stable prototype is on its way. I'll post the video at the bottom of the post.

Four standards of measurement
There are four standards as for now. The first one is the international standard, which is maintained by the bureau I mentioned above. The second one is primary standard, also known as national standard. This standard is preserved and maintained by each respective country. So Malaysian standard might as well different compared to Thailand standard, in very minute difference. It's an error though. The third one is secondary standard. Secondary standard is also known as industrial standard, usually maintained by large factories. Lastly, working standard. A standard that is used by most laboratories and researchers and many more.

These standards will try to maintain their standards as accurate and precise as possible with the international standard.

So, next time, in your daily conversation, you will finally begin to grasp fundamentally what a meter or a second means. Ha.

Our standard.. A sad reality
When my lecturer covered the above subchapter regarding standards of measurement, it really made me think, what sets our standard as a Muslim? In the university where I studied, you can even see girls with tudung labuh and guys with kopiah laughing so hard together on the same desk and eating together. I mean, what the heck?

I was moved when I posted about the death of Syeikh Said Ramadan al Buti, a friend commented. He said, although Syeikh Said was a syeikh, still when a female student came to him, you can see obviously he was shy because of the female student. Masya Allah. May Allah bless him.

Perasaan malu tidak mendatangkan apa-apa kecuali kebaikan - mafhum hadith.

We are an expert when it comes to talk about Islam. We can answer anything, refute anything, prove anything. But when it comes to akhlaq, we are the same with others. Our standard today has gone awry. Especially when it comes to ikhtilat and politics. I see even when it comes to watching movies, when some of them see erotic scenes or sexy poses, they just laugh and make a joke out of it.

I'm in an effort to re-adjust my standard. May Allah ease. May blessings of Allah come with my effort. Amin.

Salam.

p/s - Miss Anis Diyana rewarded me two times. Dulu masa nak beli pen drive, nak guna voucher tapi tak jadi, sebab voucher kena guna minimum Rm50. Masa itu memang sangat-sangat perlu pen drive. Terdesak. Pasrah lah masuk kelas miss. Alhamdulillah, dapat highest mark(rezeki Allah) dalam test, dapat satu pen drive 8GB. Second time, masa nak belanja makan adik-adik usrah. Masa itu memang kering, tapi nak belanja juga. Again, Allah blessed me, dapat highest mark lagi sekali dan kali ini miss bagi duit Rm40. Miss asalnya ajak makan sekali dengan student highest kelas lain, which happened to be girls. I rejected politely and miss gave me the money which I used all of them to treat my adik-adik usrah. Alhamdulillah. Allah memang ar Razzaq! :)

Video and reference
http://physics.nist.gov/cuu/Units/current.html
http://en.wikipedia.org/wiki/International_Bureau_of_Weights_and_Measures
Don't forget to subscribe the channel!