THE UNIVERSE, AS WE FIGURE IT OUT, IS ALL THE SPACE AND TIME TAKEN

TOGETHER. IT IS EVERYTHING, EVERYWHERE THAT EVER WAS, IS, AND WILL

BE. FOR A FACT, WE DON’T EXACTLY KNOW WHY THE UNIVERSE STARTED;
BUT WE KNOW FOR SURE, THAT IT DID. THE BIRTH OF THE UNIVERSE HAS
ALWAYS REMAINED A TOPIC TO LOOK OUT FOR AND TO FIND ANSWERS FOR.
ALMOST ALL THE CIVILIZATIONS THAT EVER EXISTED ON EARTH HAVE HAD
SOMETHING TO SAY ABOUT THIS. EACH OF THEM HAS DONE THEIR BEST TO
UNDERSTAND THE BEGINNING OF EVERYTHING. SOMETHING IS FASCINATING
ABOUT THE UNIVERSE THAT HUMANS HAVE ALWAYS BEEN CURIOUS ABOUT
IT, EVEN UNTIL THIS DAY. IN MODERN TIMES TOO, THERE HAVE BEEN MANY
THEORIES ABOUT THE ORIGIN OF THE UNIVERSE BUT THE ONE THAT TENDS
TO DESCRIBE IT THE BEST (AS PER OUR CURRENT UNDERSTANDING) IS OF
COURSE THE ‘BIG BANG THEORY’.

GEORGES LEMAITRE WAS A PRIEST FROM BELGIUM; HE WAS ALSO AN

ASTRONOMER, A MATHEMATICIAN, AND A PROFESSOR OF PHYSICS. IN 1929,
HE PROPOSED AN EXPANDING MODEL FOR THE UNIVERSE. THE BASIS OF HIS
THEORY WAS THE WORKS OF EINSTEIN AND OTHERS, WHICH HE USED TO
EXPLAIN THE REDSHIFTS OF DISTANT SPIRAL NEBULAS (LATER CALLED
GALAXIES). INITIALLY, THERE WERE NOT MANY SUPPORTERS OF HIS THEORY.
EVEN EINSTEIN INITIALLY REFUSED HIS IDEAS OF AN EXPANDING UNIVERSE
WHICH LATER HE ADMIRED LEMAITRE FOR. LEMAITRE WENT ON TO VARIOUS
CONFERENCES EXPLAINING HIS EXPANDING UNIVERSE THEORY AND CALLED
IT THE “HYPOTHESIS OF THE PRIMEVAL ATOM”. HE WAS THE FIRST WHO
SAID THAT THE UNIVERSE WAS CREATED AS A RESULT OF AN EXPLOSION OF
A PRIMEVAL ATOM AND THE RATE OF ITS EXPANSION WAS CONSTANTLY
INCREASING. THIS EXPLOSION WAS LATER CALLED THE BIG BANG.

IN 1929 EDWIN HUBBLE, AN AMERICAN ASTRONOMER; THROUGH HIS

ASTRONOMICAL OBSERVATIONS, DISCOVERED THAT ALL THE GALAXIES
WERE MOVING AWAY FROM EARTH. IN WHATEVER DIRECTION HE
OBSERVED, HE FOUND THAT THE GALAXIES WERE GETTING FURTHER AWAY
FROM EARTH IN THE VELOCITY DIRECTLY PROPORTIONAL TO ITS DISTANCE
FROM EARTH. HE ALSO OBSERVED THAT EVEN THE GALAXIES WERE MOVING
AWAY FROM EACH OTHER AND DISCOVERED THAT THE UNIVERSE ITSELF
WAS EXPANDING. SO IF THE UNIVERSE WAS EXPANDING AT AN INCREASING
RATE, THEN IT MUST HAVE BEEN SIGNIFICANTLY SMALLER IN THE PAST.
HUBBLE’S DISCOVERY CONCLUDED THAT THE UNIVERSE MUST HAVE
STARTED FROM A SINGLE POINT THAT WAS INFINITESIMALLY SMALL IN PAST.
THIS THEORY OF HUBBLE’S WAS LATER KNOWN AS THE BIG BANG THEORY.
ALTHOUGH HIS THEORY WAS SIMILAR TO WHAT LEMAITRE HAD EXPLAINED
THROUGH HIS PAPERS IN 1927, IT IS CONSIDERED THAT BY THE TIME HUBBLE
HAD DISCOVERED THE BIG BANG THEORY; HE, LIKE MOST OTHERS, WAS
UNAWARE OF LEMAITRE’S WORKS. THE BASIC MATHEMATICAL LAW BEHIND
THIS THEORY WAS DERIVED BY BOTH OF THEM AT TWO DIFFERENT TIMES.
LEMAITRE WAS THE FIRST TO FIND THIS BUT THIS LAW WAS KNOWN AS THE
HUBBLE’S LAW; UNTIL 2018. IN 2018, INTERNATIONAL ASTRONOMICAL
UNION (IAU) MEMBERS PARTICIPATED IN AN ELECTRONIC VOTING PROCESS
TO RECOMMEND THE RENAMING OF HUBBLE’S LAW TO THE HUBBLE-
LEMAITRE LAW. THIS RECOMMENDATION WAS LATER ACCEPTED BY IAU
WITH 78% VOTES IN FAVOUR.

FURTHER, IN 1964-65, TWO AMERICAN ASTRONOMERS, ARNO PENZIAS AND

ROBERT WILSON WERE DETECTING RADIO SIGNALS FROM SPACE WHEN THEY
ACCIDENTALLY FOUND A FAINT BACKGROUND NOISE IN EACH OF THEIR
OBSERVATIONS. THIS BACKGROUND NOISE WAS IN EVERY DIRECTION THAT
THEY LOOKED IN. THEY INITIALLY SUSPECTED THAT THIS WAS DUE TO THE
BIRD DROPPINGS ON THEIR RECEIVER, SO THEY CLEANED THE RECEIVER TO
MAKE A BETTER OBSERVATION. BUT, TO THEIR SURPRISE, THE BACKGROUND
NOISE GOT EVEN BETTER AND CLEARER. THIS BACKGROUND NOISE WAS
LATER OBSERVED TO BE THE LEFTOVER RADIATION FROM THE EARLIER
UNIVERSE, ABOUT 380000 YEARS AFTER THE BIG BANG. THIS RADIATION
WAS HIGHLY ENERGIZED AT THE TIME OF ITS CREATION, BUT AS THE
UNIVERSE EXPANDED, THE WAVELENGTH OF THIS RADIATION ALSO
INCREASED OVER TIME AND TODAY IT’S FOUND AT ALL PLACES IN THE
MICROWAVE REGION OF THE SPECTRUM. THIS FINDING SUPPORTED THE BIG
BANG THEORY ABOUT THE CREATION OF THE UNIVERSE AND THE
EXPANSION OF THE UNIVERSE EVER SINCE. IT HAS PROVED TO BE A
FUNDAMENTAL DISCOVERY IN THE FIELD OF COSMOLOGY. ARNO PENZIAS
AND ROBERT WILSON WERE AWARDED THE NOBEL PRIZE IN PHYSICS IN 1978
FOR THE DISCOVERY OF COSMIC MICROWAVE BACKGROUND RADIATION.

THE PHENOMENON OF STRETCHING THE WAVELENGTH OF LIGHT DUE TO

THE EXPANSION OF THE UNIVERSE TO A HIGHER WAVELENGTH SUCH THAT
THE LIGHT APPEARS TO SHIFT TOWARDS THE RED SIDE OF THE LIGHT
SPECTRUM IS CALLED REDSHIFT. A REDSHIFT CAUSES AN INCREASE IN
WAVELENGTH AND A DECREASE IN THE FREQUENCY AND ENERGY OF LIGHT.
THIS PHENOMENON IS USED BY ASTRONOMERS TO MEASURE THE DISTANCE
OF DISTANT OBJECTS SUCH AS STARS AND GALAXIES FROM US. EVEN TO THIS
DAY, THE UNIVERSE IS CONTINUOUSLY EXPANDING AT SUCH A HIGH SPEED
THAT SOME OF ITS CORRESPONDING PARTS ARE GETTING AWAY FROM EACH
OTHER FASTER THAN THE SPEED OF LIGHT.

BUT WAIT? HOW CAN THAT BE POSSIBLE? DOESN’T EINSTEIN’S THEORY SAY
THAT NOTHING CAN TRAVEL FASTER THAN LIGHT THROUGH SPACE?

WELL, EINSTEIN’S THEORY IS CORRECT, THAT NOTHING CAN TRAVEL FASTER

THAN LIGHT THROUGH SPACE, BUT IT DOESN’T FORBID THE SPACE FROM
EXPANDING ITSELF. EVERYTHING IN SPACE TRAVELS AT A SPEED BUT SPACE
ITSELF EXPANDS AT A DIFFERENT KIND OF RATE. SPACE EXPANDS AT SPEED-
PER-UNIT-DISTANCE. IT MEANS THAT, IF THE DISTANCE BETWEEN TWO
POINTS IN SPACE IS MORE, THE CUMULATIVE EFFECT OF THE EXPANSION OF
SPACE WOULD BE MORE, AND THIS GOES ON AND ON. AND HENCE, THERE
CAN’T BE A FINITE LIMIT TO THE VELOCITY OF EXPANSION OF SPACE. THE
EXPANSION OF SPACE AT SPEED-PER-UNIT-DISTANCE WAS EXACTLY THE
REASON WHY EDWIN HUBBLE OBSERVED THAT THE FARTHER THE GALAXIES
WERE, THE FASTER THEY APPEARED TO MOVE AWAY FROM US.

THERE IS A COMMON QUESTION AMONG ALL OF US, AND THAT’S, “HOW BIG
IS THE UNIVERSE?” THE SIMPLEST ANSWER TO THIS QUESTION IS THAT WE
DON’T KNOW HOW BIG IS THE UNIVERSE? IT MAY BE INFINITE. BUT WHAT
WE KNOW IS THAT THE OBSERVABLE UNIVERSE OR THE UNIVERSE THAT WE
CAN SEE THROUGH OUR TELESCOPES IS FINITE. ALTHOUGH THE UNIVERSE IS
ABOUT 13.8 BILLION YEARS OLD, THE OBSERVABLE UNIVERSE IS A SPHERICAL
SPACE OF RADIUS AROUND 46.5 BILLION LIGHT-YEARS CENTERED ON EARTH.
THIS HUGE SPHERE OF AROUND 93 BILLION LIGHT-YEARS IN DIAMETER, WITH
EARTH AT ITS CENTER IS ALL THAT WE CAN OBSERVE. DESPITE BEING ONLY
13.8 BILLION YEARS OLD, WE HAVE SUCH A LARGE OBSERVABLE UNIVERSE
BECAUSE OF THE EXPANSION OF THE UNIVERSE OVER TIME. WE CURRENTLY
CAN’T SEE ANYTHING OUTSIDE THAT SPHERE BECAUSE LIGHT HAS NOT HAD
ENOUGH TIME TO REACH EARTH FROM THERE. HOWEVER, THE OBSERVABLE
UNIVERSE IS GETTING BIGGER AND BIGGER WITH THE SPEED OF LIGHT WITH
THE PASSING OF EVERY SECOND, AND IN THE PAST, IT WAS MUCH SMALLER
IN SIZE THAN IT IS TODAY. BUT, SINCE THE CUMULATIVE EXPANSION OF
SPACE IS MORE THAN THE SPEED OF LIGHT; WE ARE CONSTANTLY LOSING
SEVERAL DISTANT GALAXIES FROM OUR OBSERVABLE UNIVERSE. THERE WILL
BE A DAY WHEN ALL THE GALAXIES APART FROM OUR LOCAL GROUP OF
GALAXIES WILL MOVE OUT OF OUR OBSERVABLE UNIVERSE.
BEYOND OUR OBSERVABLE UNIVERSE, WE DON’T EXACTLY KNOW IF THERE IS
AN END OR A LIMIT TO THE UNIVERSE. SOME STUDIES SUGGEST THAT THE
ENTIRE UNIVERSE MIGHT BE FINITE AND BIGGER THAN 250 TIMES THE
CURRENT OBSERVABLE UNIVERSE. BUT, SOME QUESTION THAT IF THE
UNIVERSE IS FINITE THEN WHAT’S IT EXPANDING INTO? AND THEY
CONCLUDE THAT THE UNIVERSE MUST BE INFINITE BECAUSE ONLY THEN IT
WILL EXPAND INTO ITSELF AS INFINITY EXPANDS INTO INFINITY. UNLESS WE
FIND SOME CONCRETE EVIDENCE TO PROVE EITHER OF THESE
EXPLANATIONS, THERE WILL ALWAYS BE A DEBATE OVER IT. THERE HAS TO
BE MORE RESEARCH TO FIND THOSE EVIDENCE AND TRY TO PUT AN END TO
THESE DEBATES.