In attaining our ideals,our meansshould be as pure as the end!

Dr Rajendra Prasad02 BEYOND CLASSROOM

THE

IS DEADKILOGRAM

LONG LIVE THE KILOGRAMFinally, 130 years after it was established, the kilogram —as we know it— retired. On May 20 2019, a newdefinition took its place – one that’s more accurate than anything we’ve had until now. Kilogram was the lastremaining unit to be based on a physical artefact, the International Prototype Kilogram (cylinder of platinumand platinum-iridium alloy). The Kg will now be defined in terms of Planck’s constant (physical constant that isthe quantum of electromagnetic action). A Times NIE report on the impact it will have on our day-to-day life

On May 20, 2019, theweight of a kilogramwas given a much-need-ed update after 130years of using a less-

than-perfect measurement. If you’resomeone who frequents the localmarket, you’d understand perfectlywhy a physical one kilogram-block— a “standard” — decides the num-ber of potatoes, onions and lady’sfingers you take home. The troublewith that, though, is that the inter-national “standard” for one kilo-gram shed milligrams of weightevery few years. Hence all other

standards had to adjust according-ly, again and again!

HOW WAS IT DEFINED BEFORE?

The kilogram has been definedsince 1889 by a shiny piece ofplatinum-iridium kept in a spe-cial glass case, the InternationalPrototype of the Kilogram (IPK),also known as Le Grand K. It ishoused at the headquarters of theInternational Bureau of Weightsand Measures (BIPM), just out-side Paris.

The IPK doesn't always weigh thesame. Even inside its three glass belljars, it picks up microparticles of dirtand is affected by the atmos-phere. Sometimes it needscleaning, which canaffect its mass. Thatcan have profoundimplications. If theprototype were to losemass, atoms would, intheory, weigh more sincethe base kilogram must bydefinition always weigh a kilo-

gram. “We live in a modernworld. There are pollutants inthe atmosphere that can stick tothe mass,” said Ian Robinson, aspecialist in the engineering, materi-als and electrical science department

at Britain’s National PhysicalLaboratory.When you just get it outof the vault, it’s slightlydirty. But the process ofcleaning or handling orusing the mass can

change its mass. So it’snot the best way, perhaps,

of defining mass. What wasneeded is something more constant.

WHY IS THE KILOGRAMREDEFINED?

A kilogram will be defined by a tinybut immutable fundamentalvalue called ‘Planck con-stant.’ The new definitioninvolves an accurateweighing machine calledthe Kibble balance,which makes use of theconstant to measure themass of an object using aprecisely measured electro-

magnetic force. What this (new) tech-nique allows us to do is to actuallymeasure mass directly at whateverscale we like, and that’s a big step

forward.

How Does It Help Us While the accuracy will bea boon to scientists, forthe average consumerbuying flour or bananas,

there will be absolutely nochange whatsoever.

HOW WILL IT BEDEFINED NOW?

1Before the kilogram, therewas the “grave.” This, theking proposed in the late

1700s, would be a standard meas-urement based on the weight of alitre of water just above the pointof freezing. (To find its “truemass,” it would be weighed in avacuum.) This inalienable measure-ment was eventually renamed thekilogram, with the gram — onethousandth of its weight — the keyunit.

2But there were a few prob-lems with the approach. Tobegin with, it was impossi-

ble to weigh an open ves-sel of liquid in a

vacuum — airpres-

sure has a substantial influence onmass. This margin of error requiredsome other absolute standard asthe core measurement – one whichwould not be affected by anything.

3The solution came a centurylater, in the form of a metalcylinder made of platinum

and iridium. This, finally, was theur-kilogram, the ultimate kilogram.It was placed beneath a RussianDoll-like series of bell jars andlocked in a vault in Paris.

4For the last 129 years, theParis original — theInternational Prototype

Kilogram — has served as the basisfor what we know as the kilogram.But that changed on May 20.

K I B B L E F O R K I L O G R A MWWhhiillee LLee GGrraanndd KK ggaavvee mmeeaassuurree-mmeennttss wwiitthh aann uunncceerrttaaiinnttyy ooff 5500mmiiccrrooggrraammss,, tthhee KKiibbbbllee bbaallaannccee ccaannnnooww ggiivvee eexxaacctt mmeeaassuurreemmeennttss ooff aakkiillooggrraamm hhaavviinngg aa mmaarrggiinn ooff eerrrroorrwweeiigghhiinngg aass mmuucchh aass aa qquuaarrtteerr ooff aanneeyyeellaasshh ((11//1100,,0000,,0000,,000000 aa kkiillooggrraamm))..“On (May 20, 2019), you won’t seeany change in our daily lives,”Richard Davis, an emeritus researchphysicist at the International Bureauof Weights and Measures, told ‘TheAssociated Press’. WWhhiillee tthhee uuppggrraaddeetteecchhnniiccaallllyy aaffffeeccttss aallll tthhee wweeiigghhiinnggssccaalleess iinn tthhee wwoorrlldd,, aass tthhee cclloocckkssttrruucckk 0000..0011 aamm oonn MMaayy 2200,, ggrroo-cceerriieess,, aattttaa aanndd ggoolldd ccooiinnss ssttiillll ccoosstteexxaaccttllyy tthhee ssaammee ppeerr ggrraamm..The minute inaccuracies correctedby the new system were not felt inbakeries or hypermarkets, but williimmppaacctt rreesseeaarrcchh,, ttrraaddee aanndd iinndduuss-

ttrriieess.. IInn ffiieellddss lliikkee ccoommppuuttiinngg,, pphhaarr-mmaacceeuuttiiccaallss aanndd cclliimmaattee sscciieennccee,,pprreecciissee mmeeaassuurreemmeennttss mmaayy mmaakkee oorrbbrreeaakk ccoonnsseeqquueenncceess.. It may take more than a few monthsfor the redefined kilogram to takefull effect in Indian industries,according to reports.

REVISION WHAT DO YOU MEASURE IN KG CHOOSING GRAMS OR KILOGRAMSWhen you’re weighing itemsusing metric measurements, it’simportant to choose the rightunit of measurement. The unitsof measurement for weight aregrams (g) or kilograms (kg), buthow do you choose which touse? As a general rule, youweigh light items in grams andheavier items in kilograms. Youweigh things in grams eitherbecause they’re light orbecause you’re measuring small

amounts of them. One way to help you decidewhether to use grams or kilo-grams is to try and judgewhether the item you need toweigh is likely to be heavier orlighter than a bag of sugar (1kilogram in weight). If you thinkthe item will weigh less, thenit’s probably best to use grams.If you think it will weigh more,then kilograms would probablybe more suitable.

You can writeweights in differentways, using frac-tions or decimals.For example:

• 500 GM = 1/2 KG OR 0.5 KG• 1,500 GM = 1. 1/2 KG OR 1.5 KG

TAKE A VIRTUAL

EXPLORE AND MORE(WWW.EXPLORATORIUM.EDU)Located in San Francisco, California,the Exploratorium is an interactive sci-ence museum that lets you explore theworld through science, art and humanperception. It encourages you to touch,listen, see, smell and even taste theworld around you!

WHAT CAN YOU DO: ACTIVITIES: Want to make your own saltvolcano? Or how about making tinselfly? This website contains a plethora ofactivities that will keep you on your toesthe entire summer. The activities arein the form of experiments you can doat home. They can be safely performedunder adult supervision by followingthe step-by-step guide given on the site.The activities cover a range of topics.

HISTORICALLY SPEAKING(WWW.NHM.AC.UK)The Natural History Museum in Lon-don is one of the oldest and most fa-mous museums around. It firstopened in 1881 and receives around5 million visitors annually.

WHAT CAN YOU DO: COLLECTIONS:You can view the col-lections online and read the colour-ful stories behind them. What’s more,you can even take part in ongoingprojects, contribute to scientific re-search and help scientists out in theirwork.READ UP: You can read up on sciencenews, latest papers and theories in thissection.

WHAT CAN YOU DO:EVENTS: You can catch liveevents happening at the mu-seum on its website. They in-clude live chat sessions withchildren around the world

and discussionsby scientists. CONNECTIONS:You can take a virtual tourof the museum on the site.You can access photo-graphs and videos of itscollections - both past andpresent. You can connectwith the museum authori-ties and share your storyon how aviation and space-flight transformed yourworld, and explore whatothers have to say.

WHAT YOU LEARN:1) Inquiry-based learning2) Experimentation

WHAT YOU LEARN:Exposes you to the latest scientific discoveries and research.

ALL ABOUT SCIENCEWWW.SCIENCEMUSE-UM.ORG.UKBased in London, it con-tains a huge collection ofrelics from the IndustrialRevolution, including

George Stephenson'sRocket.

WHAT CAN YOU DO: Exhibits: One ofthe popular

exhibits is Robotsthat charts the 500

years or so of the

evolution of the robot.Another interesting one isThe Cables That ConnectOur World. This exhibittraces the history of com-munication right from thelaying of telegraph cables inthe 19th century to mod-ern-day cloud computing.Other exhibits are on thehistory of mathematics andthe statistical work ofFlorence Nightingale.Games and apps: You canexplore brain-teasing puz-zles or learn about sciencewith a range of games andapps. You can download thegames from the website or

any playstore.

WHATYOU LEARN:

The history of sci-ence and important sci-

entific discoveriesmade over time

Museums are known as cathedrals of science.Featuring awe-inspiring exhibits, they fuel ourimagination. From the Natural History Museum inLondon to the Exploratorium in San Francisco,take an online tour of some of the world’s bestscience museums. These websites will help you

live this experience digitally

HISTORY OF KG

WHAT YOU LEARN:1) History of aviation.

2)The latest in the aviation and spaceflightindustry.

SPACE ANDBEYOND(AIRAND-SPACE.SI.EDU)

The National Airand Space Muse-

um in WashingtonDC forms part

of the Smithsonian Institution and is one

of the best science mu-seums in the world. Itis also one of the bestaviation and humanflight history museumsin the world.

SCIENCE TOUR