Inflationary Cosmology and Multiverse Theory

-written by Radha Mittal, edited by Muskan Aggarwal

In an early period during the formation of our universe, the volume of space started expanding rapidly, and this period is defined in a cosmological model known as inflationary cosmology. This theory gives us probable potential answers to some problems in our standard cosmological models, especially concerning the multiverse.

Understanding the entire universe depends decisively on understanding the small units of matter and their basic interactions. Inflationary cosmology is a remarkably successful framework for exploring these relationships between particle physics and gravity. Inflation makes some predictions about the current state of the universe. For example, overall shape, massive smoothness, and smaller structures have been evaluated with unprecedented accuracy by a new generation of astronomical measurements.

History of the universe to explain the multiverse
History of the Universe – gravitational waves are hypothesized to arise from cosmic inflation, a faster-than-light expansion just after the Big Bang

It explains the flatness of the universe and about its homogeneity. Inflation explains that when the universe was microscopic, inflation began and expanded the universe to a vast size. It was big and inaccessible to various parts, but its smoothness was maintained. 

The expanding universe has a cosmological horizon. This marks the limits of the parts of the universe that the observer can see, and the more familiar horizon caused by the curvature of the Earth’s surface. Light (or other radiation) emitted from an object across the cosmic horizon of the accelerating universe cannot reach the observer because the space between the observer and the object expands rapidly. 

According to inflation theory, our observable universe is part of a larger and more inclusive universe. You can say it very well and multifaceted. Our universe is flat because it can be a small part of the larger universe/multiverse. And this may be curved. Now, the question arises. What kind of power can exhaust the universe so quickly? There are many terms for this power, such as dark energy. Or it is a more robust version of the dark energy that caused inflation in the first place, and in a weaker way, it works for the normal expansion of the universe.

Alan Guth’s Multiverse Model

In 1929, we learned that our universe was expanding for the first time in history. Before that, scientists thought that the universe had to be static. Einstein introduced the cosmological constant when he learned that his general theory of relativity equations represents an expanding universe. When humans embraced the expanding universe, the next idea was what the universe was like in the past. In dense, hot areas, any problems needed to be close. Then there was a pronounced reaction to the singularity. The universe was born from something.

But now, the idea that the universe was born after the Big Bang is not fully supported. The physics equation did not work at the singularity and sounded too sacred. After discovering the CMBR, many researchers such as David Wilkinson and Jim Peebles suggested that all the matter and energy of the universe came from the previous collapse of the universe. The universe was initially filled with energy and photons. Experiments at the LHC have shown that high-energy photon collisions can generate particle pairs such as electrons and positrons.

You need to follow the same path as the hot big bang model to understand the gas model. In the early universe, everything was very chaotic, and because of the exceedingly high energy, the universe was full of radiation. At that time, all four fundamental forces were integrated into one force. As the expansion progressed, the symmetry broke, and all the forces were separated. It was an unstable stage, producing more energy that would not have been there without it. That energy caused an anti-gravity explosion. The universe was also expanding from the beginning, but this boost rapidly increased its expansion rate.

The world of inflation has become a paradigm for concrete realization. There have been attempts to achieve inflation in supergravity and string models, modified gravity theory, or additional dimensions.

Chaotic inflation is currently the most advanced model. It has a much more significant magnitude than our current horizon, and we predict that the universe will consist of many different, almost separate mini universes.


Inflation solves some of the problems of the Big Bang cosmology discovered in the 1970s. Inflation was first proposed in 1979 when Alan Guth was investigating the question of why magnetic monopoles are not found today. According to the general theory of relativity, he discovered that a false vacuum of positive energy produced an exponential expansion of space.

It soon became apparent that such an extension would solve many other long-standing problems. These problems arise from the observation that the Big Bang had to have very finely tuned or “special” initial conditions for the universe to appear as it is today. Inflation seeks to solve these problems by providing a dynamic mechanism that propels the universe into this state, making the universe like us much more likely in the context of the Big Bang theory.



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