Universe or Multiverse? - Neutron Stars and Black Holes Lecture 14

Overview

Explore the fascinating realm of cosmology in this comprehensive lecture on the universe and multiverse theories. Delve into key concepts like the expanding universe, cosmic microwave background, and the age of the universe. Examine troubling aspects such as the horizon and flatness problems, and discover how inflationary theory attempts to resolve these issues. Learn about cosmological phase transitions, symmetry breaking, and gauge theories of elementary particles. Investigate various inflationary models, including chaotic and eternal inflation, and their implications for the multiverse concept. Contemplate profound questions about the beginning of the universe and alternative cosmological models like cyclic universes. Gain a deeper understanding of cutting-edge ideas in theoretical physics and cosmology through this engaging 2-hour lecture by G. Srinivasan from the Raman Research Institute.

Syllabus

Time: AM
Neutron Stars and Black Holes Lecture - 14: Universe or Multiverse?!
Universe or Multiverse?!
What have we learn about our universe during last
Our Universe is expanding
The present expansion rate
Age of the Universe
The Universe is not only expanding,it is Accelerating!
Geometry of the universe is Euclidean
The geometry of the Universe
Critical density
The Energy-Density Budget of the Universe
The Present Revolution in Astronomy
A Singularity Theorem
Some troubling things about our universe
The "Horizon" problem
Isotropy of the Cosmic Microwave Background
At t~10-36 sec
At Planck time =10-43 sec, the size of the universe exceeded the causality scale by 10 power 28
The "Flatness" problem
How to fix the Horizon Problem
Why would the early universe expand exponentially?
Inflationary Universe
The "Heavy Nothing" or Vacuum Energy
Matter & Radiation exert positive pressure
Vacuum exerts negative pressure!
Exponential Expansion
An initial exponential expansion
Ingredient of Inflation
Unification of forces Cosmological Phase Transitions
Symmetry Breaking and Phase Transitions
Landau's theory of second order transition
First order Phase Transition
Supercooling and Superheating
Nucleation during transition
Cosmological Phase Transitions
Symmetry Breaking and Phase Transitions
Gauge Symmetry
Gauge Theories of elementary particles
Vacuum Driven Acceleration
Exponential Expansion
A curved surface expands by a factor of 3 in each panel.
But there are problems!
The initial hope was not to be!
'New' Inflation
Slow Roll Inflation
New Inflation - a summary
Inflation: underlying assumptions
Chaotic Inflation
Robertson-Walker Universe
The essence of Chaotic Inflation
Inflation is generic!
Eternal Inflation
Multiverses
Was there a beginning?
History in "Imaginary time"
Cycles of time
Wrap Up