Research

Cosmology

My research interests lie broadly in theoretical cosmology and gravitation, with a focus on understanding the fundamental physics of the early universe and the geometric structure of spacetime.

I am particularly interested in how high-energy particle physics, quantum field theory, and gravitational dynamics interact to shape the cosmological evolution.

Baryogenesis

In simple words, immediately following the Big Bang, the universe contained equal amounts of matter and antimatter. When matter and antimatter collide, they destroy each other and leave behind only energy. If this perfect balance had continued, all particles would have been destroyed, leaving a universe completely empty of solid objects.

However, a process known as baryogenesis occurred. For reasons scientists are still researching, the universe produced slightly more matter than antimatter. Specifically, for every one billion antimatter particles, there were one billion and one matter particles.

Once the universe cooled and the widespread collisions stopped, all of the antimatter was destroyed. The small fraction of remaining matter survived to form every galaxy, star, planet, and living thing
that exists today.

Simply, the question is...
WHERE IS ALL THE ANTIMATTER?
or at least philosophically...
WHY DO ONLY 'MATTER' MATTERS TO THE UNIVERSE?
or at most sarcastically...
WHERE DOES ANTI-RAGHAV LIVE? IS HE ALIVE???

Cosmic Microwave Radiation

Image Courtesy: ESA/Planck Collaboration

The Cosmic Microwave Background (CMB) is the leftover thermal radiation from the big bang formed during the period of recombination, measured at temperature1 T0 = 2.72548 ± 0.00057 K. Here we see CMB has tiny anisotropies (temperature fluctuations) of the order ∆T ∼10^(−5) The fact that the temperature fluctuations are so small is telling us that the early universe was extremely smooth. Data from missions like COBE, WMAP, and Planck have provided high precision maps of the CMB. One can enjoy the 3D view at www.thecmb.org.

Two Major Probes of Antimatter

This asymmetry between matter and antimatter can be determined independently in two different ways:

1.) from the abundances of light elements in the intergalactic medium (IGM) produced during Big Bang Nucleosynthesis (BBN)
2.) from the acoustic peaks observed in the power spectrum of temperature fluctuations in the CMB

It is remarkable that two completely different probes of the baryon content of the Universe
(the synthesis of light elements occurred during the first 3 minutes of the Universe evolution,
and the photons decoupling occurred when the Universe was 400 thousand years old)
give compatible asymmetry measure:

~ 10^(-10)

...that is roughly one antimatter particle in ten billion matter particles !!
This represents one of the great successes of modern Cosmology.

My_Thesis_Preview .pdf

That's my first official research
document.... my MS Thesis!

In this, I have explored a particular method i.e
Gravitational Baryogenesis , which can possibly generate this observed measure of asymmetry, considering our universe
is spatially homogenous but `nearly' anisotropic (deviating from a fundamental assumption of standard cosmology, that is,
COSMOLOGICAL PRINCIPLE) on large scales (>100 Mpc).

Possibly described by any one of the fundamental anisotropic Thurston geometries which are categorized based on their topology.

Though my thesis ended up asserting the failure of achieving the
desired asymmetry measure through any of the anisotropic
geometries considered as the spatial part of our universe,
under the assumption that the radius of curvature of such
geometries remain constant and larger than the Hubble radius throughout the evolution of the universe.

Remember?
"We are trying to prove ourselves wrong as quickly as possible, because only in that way can we find progress."
---- Richard Feymann

Page updated

Google Sites

Report abuse