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Cosmology education General Relativity Mathematics Physics Science Uncategorized

Revisiting Kaluza Klein Theory

In the video below, I explain how to derive Kaluza Klein action which occurs from generalizing the Einstein-Hilbert action to five dimensions. The grand implication of this is that gravity and electromagnetism are unified!

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Cosmology General Relativity Mathematics Physics Science

New Article Published in Journal of Geometry and Physics

Our new article was recently published in The Journal of Geometry and Physics. It is shown that under certain conditions, The Einstein Field Equations have the same form as a fold bifurcation seen in Dynamical Systems theory, showing even a deeper connection between General Relativity and Dynamical Systems theory! (You can click the image below […]

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Cosmology General Relativity Mathematics Physics Science

Attempts at a General Einstein Equation for an Arbitrary FLRW Cosmology

I tried to derive a general Einstein field equation for an arbitrary FLRW cosmology. That is, one that can handle any of the possible spatial curvatures: hyperbolic, spherical, or flat. Deriving the equation was easy, solving it was not! It ends up being a nonlinear, second-order ODE, with singularities at a=0, which turns out to […]

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Cosmology General Relativity Mathematics Physics Science

New paper published on cosmological singularities

My new paper has now been published in Annalen der Physik, which is a great honour, because 100 years ago, Einstein’s General Theory of Relativity was also published in the same journal. This paper describes a method by which one is able to determine whether a given spatially flat cosmological model produces finite-time singularities, and […]

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Cosmology General Relativity Mathematics Physics Science

Making a Cosmological Model

What goes into making a cosmological model? Here is a presentation (that was part of my Ph.D. dissertation) that I have reproduced and embedded here to describe what actually goes into the making of a cosmological model. After describing some general properties, I describe specifically a early-universe model that contains a viscous fluid and a […]

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Cosmology General Relativity Mathematics Physics Science

Pi Day and Einstein 

  

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Cosmology education General Relativity Mathematics Physics Science

On Gravitational Waves

Since I expect the concept of gravitational waves to once become very popular in the next few days, I wrote some quick notes on them, I.e., where they come from. They are handwritten, as I didn’t have time to LaTeX them, but, hopefully, they’ll be useful to interested readers!  Also note that, gravitational waves are […]

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Cosmology education General Relativity Mathematics Physics Science

Equations Published in a Cosmology Textbook

One of my earliest works was deriving equations which themselves were forms of Einstein’s field equations that described the state of the early universe, which may have had dominant viscous effects. I was delighted to learn that these equations were published in Springer’s Handbook of Spacetime Cosmology textbook. Here is a snapshot of the textbook […]

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Cosmology General Relativity Mathematics Physics Science

Black Holes, Black Holes Everywhere

Nowadays, one cannot watch a popular science tv show, read a popular science book, take an astrophysics class without hearing about black holes. The problem is that very few people discuss this topic appropriately. This is further evidenced that these same people also claim that the universe’s expansion is governed by the Friedmann equation as […]

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Science

Some of Lemaitre’s Contributions

Many have no doubt heard of Lemaitre’s important contributions to cosmology theory. In this brief post, I provide links to Lemaitre’s original papers: 1. Lemaitre proposing that the universe is expanding: Full paper available here for free 2. Lemaitre proposing that the universe had a beginning, the original Big Bang model: Full paper requires subscription […]