Dmitry Podolsky has got his PhD from Landau Institute for Theoretical Physics. He currently works as postdoc at Case Western Reserve University. He is also one of the editors of NEQNET.

10. Introduction into perturbation theory in general relativity 3 (Inflationary perturbations 3)

Sorry, but today’s post is going to be rather short: the end of this week is a lot busier than usual, since I am trying to finish a couple of papers. One of them is about intrinsic instability of de Sitter spacetime (became a hot subject recently; also, it is one of the most important [...]

9. Introduction into perturbation theory in general relativity 2 (Inflationary perturbations 3)

Today I will continue our discussion of the perturbation theory in general relativity (please see the previous post here); in particular, I will focus my attention on the issue of gauge invariance. 1. Gauge transformations Let us consider how the metric modes we have constructed in the previous post change under coordinate transformations. We introduce [...]

8. Introduction into perturbation theory in general relativity (Inflationary perturbations 3)

Before turning to the discussion of the perturbation theory in general relativity, let me briefly remind the outline of the two previous posts (1 and 2). As we have found, Newtonian perturbation theory works well at relatively small scales (much less than hundred of MPcs), but predicts exponential growth of infrared adiabiatic modes. We have [...]

7. Newtonian perturbation theory 2 (Inflationary perturbations 2)

This is the 5th post in the series based on my lectures on inflationary perturbations at the University of Helsinki. Today I will continue to discuss Newtonian perturbation theory (the first post on this topic can be found here). Let me remind you that my ultimate goal is to explain the features (filaments and voids) [...]

6. Newtonian perturbation theory 1 (Inflationary perurbations 2)

This is the 4th post in the series based on my lectures on inflationary perturbations at the University of Helsinki. I decided to postpone the basics for the next time and rush a bit; today instead we will start to develop the theory explaining the large scale sctructure of the Universe as described here. The [...]

Death of Arthur C. Clarke

Arthur C. Clarke, one of the best science fiction authors of 20th century, died today at Colombo Sri Lanka. The death finally cought him in the age 90; he was planning to be the guest of first hotel in the Earth’s orbit in 2017, and it is sad that he was unable to fulfil his [...]

5. The Universe is expanding (Inflationary perturbations 1)

This is the 3rd post in the series based on my lectures on inflationary perturbations at the University of Helsinki (previous ones can be found here and here). Today I am going to finally start constructing some theoretical basis for the future posts on inflationary perturbations Probably, the most important observation ever made by an [...]

4. Large scale structure of the Universe. In other wavebands (Inflationary perturbations 1)

In this post, I will briefly describe what astronomers see on the sky in wavebands other than optical as well as what observations in other wavebands are especially good for. The best instruments to observe the Universe one can have are the space based ones. Currently, the space observatories – the facet eyes of our [...]

3. WMAP 5 year – more

I was asked over email how well it is known that the Universe is spatially flat. According to just released WMAP 5 year dataset , the spatial curvature contribution is bounded by at the 95% confidence level with prior on the equation of state for the dark energy , according to 5 year data

2. Large scale structure of the Universe. In visible light (Inflationary perturbations 1)

This post is the first one in the series devoted to discussion of the large scale structure of the Universe, inflationary cosmology and inflationary perturbation theory. The series will be essentially based on the lectures I am giving currently at the University of Helsinki for graduate students and advanced undergrads. Today, I am going to [...]