Almost a year ago being in Seoul I was thinking about visiting say the Far East Federal University with a seminar. Trying to find any information on their official website about people working on HEP I realized, how a complicated task it is. Almost all webpages of institutions contain very fragmented, insufficient, outdated or even wrong information on the subject, that makes it very hard to understand who is working at which institute and what are his/her research interests. Precisely to overcome this problem I started developing a website, storing a database for all HEP-people.
Showing posts with label interesting stuff. Show all posts
Showing posts with label interesting stuff. Show all posts
05 April, 2016
19 November, 2013
Video Lectures on MathPhys
Here are some sources where one can find video lectures on basics of theoretical physics and/or mathematical tools that we use. Of course, this list is not comprehensive, but may be useful anyway. (All links open in a new window.)
1. Perimeter Institute graduate lectures for 2012/2013 can be found here . The other years from 2009 to 2014 are hidden in the "Course" menu of this page.
2. Seminars at Isaas Newton Institute in Cambridge. Navigation on this site may be not clear, so lets try find some videos there. Firstly, one chooses a program. Go to "Past programs" that is in the bottom of the page, then find there entry The Mathematics and Applications of Branes in String and M-theory . Click "Full list" in the left menu list and that's done.
3. YouTube channel of Stanford University contains a lot of information on the university itself and in addition one may find interesting lectures there. E.g. lectures on cosmology by Prof Leonard Susskind of Stanford University.
I'm sure that there are much more of this kind of sites, please add in the comments below if you know some. This will be of much help.
1. Perimeter Institute graduate lectures for 2012/2013 can be found here . The other years from 2009 to 2014 are hidden in the "Course" menu of this page.
2. Seminars at Isaas Newton Institute in Cambridge. Navigation on this site may be not clear, so lets try find some videos there. Firstly, one chooses a program. Go to "Past programs" that is in the bottom of the page, then find there entry The Mathematics and Applications of Branes in String and M-theory . Click "Full list" in the left menu list and that's done.
3. YouTube channel of Stanford University contains a lot of information on the university itself and in addition one may find interesting lectures there. E.g. lectures on cosmology by Prof Leonard Susskind of Stanford University.
I'm sure that there are much more of this kind of sites, please add in the comments below if you know some. This will be of much help.
22 July, 2013
What is...?
I have found an interesting series of articles under the common topic "What is..?" One can browse a small archive of these articles or go to the home page home page of AMS Notices to search for more.
In these notes one can find brief introductions to some mathematical stuff that is usually hard to understand reading books or articles.
The ones that I would like to recommend for reading are "What is a gerbe?" by Nigel Hitchin and "What is a G_2 manifold?" by Spiro Karigiannis. These are interesting because gerbes appear as nice generalisations of fibre bundle and are relevant to the recently developed duality covariant approaches. G2 manifolds play the same role for M-theory compactifications as Calaby-Yau manifolds play for stringy compactifications. These are 7-dimensional (compact) manifolds with a lot of nice properties.
In these notes one can find brief introductions to some mathematical stuff that is usually hard to understand reading books or articles.
The ones that I would like to recommend for reading are "What is a gerbe?" by Nigel Hitchin and "What is a G_2 manifold?" by Spiro Karigiannis. These are interesting because gerbes appear as nice generalisations of fibre bundle and are relevant to the recently developed duality covariant approaches. G2 manifolds play the same role for M-theory compactifications as Calaby-Yau manifolds play for stringy compactifications. These are 7-dimensional (compact) manifolds with a lot of nice properties.
05 September, 2012
FQXi Essay Contest
The FQXi community closed its essay contest that started in spring. The topic is "Which of Our Basic Physical Assumptions Are Wrong?".
Actually, there are a lot of these essays, and I read only one, written by Sabine Hossenfelder. She assumes in this essay that what we observe as a Planck constant is just a vacuum expectation value (VEV) of a scalar field. Thus, we see here a kind of spontaneous symmetry breaking.
Increasing temperature restores this symmetry and she assumes that the Planck constant goes top zero at high energies. That provides gravity decoupling from matter since newtons constant is proportional to Planck constant
\begin{equation}
G=\frac{\hbar c}{m_{Pl}^2}.
\end{equation}
This solves one of the problem — singularity of the initial state of the Universe. Since we have no interaction between matter and gravity at high temperatures then high densities do not form space-time singularities. Something similar happens inside black holes: as the process of a black hole formation is adiabatic (nothing escapes from it), then entropy is conserved and temperature grows while BH is collapsing.
The other problem arises when we are going to quantize gravity. It is known that gravity can be quantized perturbatively, but it is a non-renormalized theory. Setting $\hbar$ to go to zero as temperature increases solves this problem at high energies: gravity is just classical.
An interesting fact is that there disappears the notion of quantumness in this consideration. It appears as some kind of interaction of fields with VEV of a field of special type.
Actually, there are a lot of these essays, and I read only one, written by Sabine Hossenfelder. She assumes in this essay that what we observe as a Planck constant is just a vacuum expectation value (VEV) of a scalar field. Thus, we see here a kind of spontaneous symmetry breaking.
Increasing temperature restores this symmetry and she assumes that the Planck constant goes top zero at high energies. That provides gravity decoupling from matter since newtons constant is proportional to Planck constant
\begin{equation}
G=\frac{\hbar c}{m_{Pl}^2}.
\end{equation}
This solves one of the problem — singularity of the initial state of the Universe. Since we have no interaction between matter and gravity at high temperatures then high densities do not form space-time singularities. Something similar happens inside black holes: as the process of a black hole formation is adiabatic (nothing escapes from it), then entropy is conserved and temperature grows while BH is collapsing.
The other problem arises when we are going to quantize gravity. It is known that gravity can be quantized perturbatively, but it is a non-renormalized theory. Setting $\hbar$ to go to zero as temperature increases solves this problem at high energies: gravity is just classical.
An interesting fact is that there disappears the notion of quantumness in this consideration. It appears as some kind of interaction of fields with VEV of a field of special type.
12 July, 2012
Official string theory site
Found very interesting "official" superstring theory website http://superstringtheory.com. One can read there about string theory on basic and advanced level. Actually, the advanced level is basic for a PhD student and very understandable.
Nice reading during breakfast or leasure time.
Nice reading during breakfast or leasure time.
30 June, 2009
Ice ages
There is such a hypothesis that the Ice Ages on The Earth are somehow connected with The Solar System moving through The Galaxy spiral branches. It is said that the cosmic particles flow changes when we go in and go out from a spiral arm. These particles can cause clouds condensation nuclei formation in the Earth atmosphere. And therefore there become less sunlight on the Earth surface and the climate becomes colder.
Recently there appeared the paper astro-ph: 0906.2777v1 where this hypothesis is said to be wrong. They have found no correlation between moving of The Sun through The Galaxy and the Ice Ages. They used the distribution of carbon monoxide molecules taken from the infrared data of the NASA's Spitzer mission.
Recently there appeared the paper astro-ph: 0906.2777v1 where this hypothesis is said to be wrong. They have found no correlation between moving of The Sun through The Galaxy and the Ice Ages. They used the distribution of carbon monoxide molecules taken from the infrared data of the NASA's Spitzer mission.
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