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WHEN IT COMES TO
UNIVERSE, WE SERIOUSLY DON’T KNOW MUCH ABOUT IT (THOUGH WE HAVE SOME IDEAS).LET’S
TAKE A LOOK AT THE COMPOSITION OF THE UNIVERSE ~ 68 %=DARK ENERGY ,~27% DARK MATTER AND ROUGHLY 5%
NORMAL(BARYONIC) MATTER.
LET’S TALK ABOUT DARK
MATTER FIRST. THE EFFECT OF DARK MATTER WAS FIRST
NOTICED IN 1933 WHEN FRITZ ZWICKY NOTICED THAT THE GALAXIES IN THE COMA CLUSTER
WERE MOVING WAY TOO FAST TO BE GRAVITATIONALLY BOUND WITHIN THE CLUSTER. IT WAS
CALLED ‘DUNKIE MATERIE’ THEN.
AS PER NEWTON’S LAW OF GRAVITATION, BECAUSE
OF WEAKENING OF THE FORCE OF GRAVITY ON INCREASING THE DISTANCE, THE GRAPH OF
VELOCITY VS DISTANCE FROM THE CENTRE OF ROTATION SHOULD INCREASE LINEARLY TO A
VALUE AND THEN DECREASE. BUT WHAT WE OBSERVE IS THE LINEAR INCREASE AND THEN THE
CONSTANCY IN THE RELATION. V=root(GM/R) ;IT
MEANT THAT THERE IS MAJORITY OF MASS RESENT IN THE HALO OF THE GALAXY.WE CALL
IT ‘DARK MATTER’.
LETS TAKE A LOOK AT VARIOUS POSSIBILITIES
ABOUT WHAT IT CAN BE--
1. IT IS A FORM OF PARTICLE THAT IS VERY
DIFFICULT TO DETECT.
- IF DARK MATTER HAS FORMED FROM THE
BARYONIC MATERIAL, IT SHOULD BE DETECTABLE BY THE GRAVITATIONAL LENSING. IT
SHOULD BE A MACHO- I.E. MASSIVE COMPACT HALO OBJECT (INCL. FAILED STARS, BLACK
HOLES).THE SAD STORY IS EVEN IF WE TAKE ACCOUNT OF THEIR MASSES BY GRAVITATIONAL LENSING , WE
COULD NOT ACCOUNT FOR THE MASS NEEDED.
2. GRAVITY BEHAVES DIFFERNTLY ON LARGE
GALACTIC SCALES (F VARIES AS 1/R)
THIS IS CALLED MOND (MODIFIED VERSION OF
NEWTONIAN DYNAMICS).ACCORDING TO THIS, BARYONS AND DARK MATTER ARE ESSENTIALLY
THE SAME. LET’S TAKE A LOOK AT THIS ARGUMENT VIA BULLET CLUSTER- THESE ARE THE
PAIR OF GALAXIES WHOSE COLLISION LOOKED LIKED THE SHAPE OF A BULLET.WHEN
COLLISION HAPPENED , THE STARS OF THE GALAXIES PASSED RIGHT THROUGH AND THE GAS
WAS IN THE MIDDLE .IF DARK MATTER CONSISTED OF BARYONS, THE MOST MASS SHOULD BE
CONCENTRATED IN THE GASEOUS REGION. BUT THE MASS WAS CONCENTRATED IN THE REGION OF GALAXIES.
THIS SHOWED THAT THE DARK MATTER IS A PARTICLE THING.
3. PARALLEL UNIVERSE THEORY-
IT STATES THAT THE EXTRA GRAVITATION IS ATTRIBUTED TO A PARALLEL UNIVERSE, WHICH CAN INTERACT TO US ONLY BY GRAVITATIONAL EFFECTS.
IT STATES THAT THE EXTRA GRAVITATION IS ATTRIBUTED TO A PARALLEL UNIVERSE, WHICH CAN INTERACT TO US ONLY BY GRAVITATIONAL EFFECTS.
4.EXTENSION/MODIFICATION TO PARTICLE
PHYSICS-
THESE PARTICLES MAYBE WIMPS- (WEAKLY INTERACTING MASSIVE PARTICLES) THAT EMERGE FROM FANCY MATHEMATICS AND SUPERSYMMETRY. THE POSSIBLE CANDIDATES ALSO INCLUDE HEXAQUARKS* (I.E THE PARTICLE OBTAINED BY THE COMBINATION OF 6 QUARKS-IT IS HYPOTHESIZED THAT THEY HAVE VERY LARGE DECAY PERIOD ).
THESE PARTICLES MAYBE WIMPS- (WEAKLY INTERACTING MASSIVE PARTICLES) THAT EMERGE FROM FANCY MATHEMATICS AND SUPERSYMMETRY. THE POSSIBLE CANDIDATES ALSO INCLUDE HEXAQUARKS* (I.E THE PARTICLE OBTAINED BY THE COMBINATION OF 6 QUARKS-IT IS HYPOTHESIZED THAT THEY HAVE VERY LARGE DECAY PERIOD ).
TILL NOW, FROM WHAT ALL WE KNOW , ALL THE
COMPUTER SIMULATIONS THAT THE SCIENTISTS HAVE RUN, IT’S SURE THAT WE NEED DARK
MATTER FOR THE EVOLUTION OF THE UNIVERSE FROM THE HOT PLASMA TO THE BEAUTIFUL
STRUCTURE WE SEE TODAY. AND THAT IT SHOULD BE COLD (I.E IT SHOULD NOT BE MOVING AT VERY HIGH RELATIVISTIC
SPEEDS) AND POSSIBLY A PARTICLE. WE NEED MORE INFORMATION ABOUT THE FORMATION OF
GALAXIES AND THEIR BEHAVIOUR AT THE EARLY STAGE OF UNIVERSE. JAMES WEBB
TELESCOPE- WE ALL ARE WAITING FOR YOU!
Refrences-
Dr. Physics - https://www.youtube.com/user/DrPhysicsA
PBS Space Time-https://www.youtube.com/channel/UC7_gcs09iThXybpVgjHZ_7g
NASA Science Article - https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy
PBS Space Time-https://www.youtube.com/channel/UC7_gcs09iThXybpVgjHZ_7g
NASA Science Article - https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy
