tag:blogger.com,1999:blog-349831912012-02-10T15:55:48.716+01:00An independent viewpoint about quantum gravity.Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.comBlogger991100tag:blogger.com,1999:blog-34983191.post-34974989559280911722011-08-29T09:34:00.002+02:002011-08-29T09:56:10.763+02:00

The last Friday there was a very interesting paper in arxiv. I am really busy those days (and it will be so until around the 15 of September)so I couldn't still read ot completely. Still I think that I must leave notice of it here. The paper in question is title like the post entry, Geometric Models of Matter. It has three authors: Michael Atiyah, Nicholas S. Manton, Bernd J. Schroers. Among

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-38183496316335447912011-05-30T04:55:00.005+02:002011-05-30T09:48:56.878+02:00

Today there are in arxiv two articles that look really great. The firs (in the order that arxiv gives to them) is from Samir D. Mathur: Effective information loss outside the horizon. It argues that there is no loss of information inside a black hole because he information simply doesn't go inside the black hole. The abstract explains it more carefully: If a system falls through a black hole

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-78402073848611589892011-04-19T09:12:00.002+02:002011-04-19T10:59:29.527+02:00

The last week there was an article that was commented in the arxiv blog: Planets Could Orbit Singularities Inside Black Holes. The blog entry discuses this article: Is there life inside black holes?. The article is a pure classical relativity article. It study the possibility of stable orbits for planets inside a black hole, in particular in a Kerr-Newman black hole, that is, a rotting charged

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-79233744923709891462011-02-17T08:47:00.004+01:002011-02-18T10:09:26.961+01:00

Today in arxiv there is a very curious article:Quantum D-branes and exotic smooth R^4 written by Torsten Asselmeyer-Maluga, Jerzy Krol. The article is actually the second part of a previous one: Exotic smooth R^4 and certain configurations of NS and D branes in string theory. The abstract of the first (in date order) article reads: In this paper we show that in some important cases 4-

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-13578316322421559412011-02-11T08:59:00.003+01:002011-02-17T09:19:43.242+01:00

String theory deal mainly with physic at the planck scale, although it's goal is to connect to with the electroweak scale. On the other hand, nonotehcnology, deals with physics at sizes similar to the Bohr radius. There are, consequently, many orders of magnitude of difference among that two branches of physics. Because of that it is absolutely amazing to see in the title of the paper a reference

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-6119607348416934072011-01-27T09:44:00.004+01:002011-01-27T10:37:15.936+01:00

First an advert, the two topics are unrelated, well, or may be not ;). The first paper I would want to mention is this form Luis Alvarez Gaumé. Gaumé is one of the best known spanish string theorists. He is famous for the 80's paper with Witten about the (absence of) anomalies in string theory. Now he has a paper in arxiv. A Minimal Inflation Scenario. This is the abstract: We elaborate on a

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com4tag:blogger.com,1999:blog-34983191.post-37317699045864676952010-12-20T09:49:00.002+01:002010-12-20T09:55:32.789+01:00

Today in arxiv has appeared something that I had never seen before, a whole collection of review articles devoted to a single topic, the ADS/CFT. There is an "overview" article that serves as reference of the others: Review of AdS/CFT Integrability: An Overview. If I haven't counted bad there are 23 articles. And this is a review!. Clearly that is an indication of the fact that AdS/CfT is a very

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-91498862926400942342010-12-02T10:08:00.002+01:002010-12-02T11:15:07.962+01:00

This is a very brief note to tell that I have not forgotten about the blog. There are a couple of combined reason for my long absence. Possible one of the most important ones is that my favourite (and expensive) wireless keyboard is out of work because it's USB connector seems to be slightly broken. Now I must return to writing with a wired keyboard, which is uncomfortable and it results in

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-75927241816975087392010-10-05T06:36:00.002+02:002010-10-05T07:38:49.787+02:00

This last mounth happened many interesting things and there were a few good papers. Possibly I´l mention some of them in the future, but today just want to write a brief entry about a pre-idea. The energy of vacuum is an ugly problem for QFT and string theory. Both in the theoretical side, the vacuum energy would be a lot greater than 0, and in the experimental side, the universe seems to be

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-89975302607746299222010-08-30T08:43:00.002+02:002010-08-30T10:03:48.425+02:00

Reading the kea's new blog I advertised that there were two videos of Verlinde talking about emergent gravity:1)KIPT video2) Perimeter video At the beginning of this summer Verlinde had announced it's presence in a string theory conference in Madrid but, unfortunately, at last he didn't assist. Because of that I was curious to see in video what I missed in direct and looked at the first of the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-84351667446182930032010-07-26T09:34:00.005+02:002010-07-26T10:43:38.620+02:00

The great conference of the moment is ICHEP. It has a dedicated blog where very well known people as Tommao Dorigo (quantum diaries survivor), Jester (resonances) and many others are posting about the conferences. Today is a great day in the conference. In one hand the French president Nicolas Sarkozy will give a talk (not sure what he will speak about, possibly about the financiation of CERN)

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-6802989554456595242010-07-13T09:16:00.004+02:002010-07-13T09:55:22.073+02:00

WARPDRIVES Reading this post at the vixra bog I got aware of this paper: Warp Drive Basic Science Written For ”Aficionados”.Chapter II - Jose Natario. Warp drives are a nice idea. They are inspired by the TV and cinema serial Star Trek of which I am not a particular fan, although I have seen a few chapters and most of the movies. The key concept is that when you want to to go from a point A to

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com5tag:blogger.com,1999:blog-34983191.post-43102510196895019562010-06-16T04:25:00.005+02:002010-06-17T07:08:26.278+02:00

Until Friday it is very unlikely that I have time to properly read the two articles that I am going to link here. But I find that they are challenging enough to leve a note abut them. The first article was cited yesterday in the arxiv blog: New Quantum Theory Separates Gravitational and Inertial Mass (if you are Spanish and prefer reading it in that language there is a translated version by

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-81553516868445996682010-06-07T09:48:00.004+02:002010-06-07T10:20:12.814+02:00

Today there are some interesting papers in arxiv, although not so many as the previous Monday. Some of them are purely mathematical, or concern formal aspects. I like formal aspects, and mathematics, but because I had some leaks on recent phenomenology I am provisionally interested in more mundane topics. One key aspect in phenomenology is supersymmetry breaking. To begin with the MSSM (

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-57261818148841343032010-06-01T08:34:00.007+02:002010-06-02T09:45:21.150+02:00

I have talked quite often in this blog about F-theory. This is partially due to "historical" reasons, that is, the F-theory GUT revolution happened recently, while this blog growth. Also the influence of a friend of mine to let learn algebraic geometry was a plus because F-theory relies a lot in that area of maths.Of course another reason is that they are very good developed framework. But that

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-27234206458746328922010-05-10T09:13:00.004+02:002010-05-10T11:16:38.106+02:00

The most interesting paper today n arxiv hep_th is very probably this: Uber-naturalness: unexpectedly light scalars from supersymmetric extra dimensions This is the abstract: Standard lore asserts that quantum effects generically forbid the occurrence of light (non-pseudo-Goldstone) scalars having masses smaller than the Kaluza Klein scale, M_KK, in extra-dimensional models, or the gravitino

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-42164466077418874472010-04-30T09:26:00.003+02:002010-04-30T10:15:55.197+02:00

Supersymmetry is easy, isn't it?. I have posted (in spanish) a brief introduction to the subject. And I'll make more posts abut it. I am almost sure that everyone who has passed a course in QFT can understand the basics of supersymmetry. After all, you have a superpartner for every particle, that has opposite statistic. You have funny names for the superpartnerts. The partner of the electron

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-4470538617487960822010-04-28T09:01:00.004+02:002010-04-28T11:18:47.487+02:00

When I studied theoretical physics in the UAM the everybody (well, at least everybody studying he specialty of theoretical physics) favorite teacher was Enrique Álvarez. Possibly, I don't know because I never coincided with him, today Ibañez could discuss the crown, but in that times Ibañez was in CERN and didn't teach. Particularly great was his course in an asignature devoted to classical

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-3967279233261363042010-04-09T09:15:00.003+02:002010-04-10T08:09:22.998+02:00

A few days ago it was published on arxiv the following paper: Black hole/string ball production, possibly at LHC I am busy reading any, many things nowadays and I couldn't read it immediately - despite of it's few number of pages - but today, at last, I read it. The main interest of the papers is that it makes a quick review of the ideas that lead to the proposal of black hole creation on the LHC

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-19041458980261540142010-03-30T09:28:00.002+02:002010-03-30T09:32:06.397+02:00

Today at 8 30 it was expected that the LHC would make the first collisions at 7 TeV. There has been some problem and one of the beans has been lost. It is expected that around 11 a second try would be made. You can follow the events in real time in the live webcast

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-20835689479509933972010-03-18T07:44:00.004+01:002010-03-18T08:56:54.476+01:00

I have been reading in the internet about the strings 2010, which this year has place in Texas, for a while. But I had not paid too much attention because I thought that, as usually, the event would be in summer. Today I have been shocked when I saw a quick note in U duality blog saying that the conferences have been going this week. This wee I was not particularly busy and if I just would

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com4tag:blogger.com,1999:blog-34983191.post-77610785420754669172010-02-24T07:40:00.006+01:002010-03-17T23:33:33.720+01:00

Yeahm I know it is a somewhat misleading title ;).What I am meaning is that a nobel laureate -and a very famouse one, the cosmologist Geogre F. Smoot- wrote a paper (in collaboration with other people) in the subject of entropic force. It is this: Entropic Accelerating Universe This is the abstract: To accommodate the observed accelerated expansion of the universe, one popu-lar idea is to

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com8tag:blogger.com,1999:blog-34983191.post-28204509748096902792010-02-15T10:06:00.002+01:002010-02-15T10:34:52.554+01:00

This new year "sensation" has been a paper by the well known string theorist Erick Verlinde about a possible entropic force like origin of gravity. The actual paper is this. The article has been extensively discussed in the blogosphere and I will not add too much about it. The main reason of publishing about the topic is that I commented to a friend it's existence and he asked me for the link.

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-68070077255519001742010-01-19T09:28:00.003+01:002010-02-05T03:49:48.335+01:00

In science fiction novels of not too long ago it was presented the idea of porting a whole library of textbooks in a pocket computer. Well, that is possible now. One option are the smartphones, specially the incoming new generation with screens of up to 4 inches or even greater. In today phones it is also possible, but possible the screens are too small to do a decent reading and they are useful

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com8tag:blogger.com,1999:blog-34983191.post-65661902782252715882009-12-31T08:30:00.003+01:002009-12-31T09:51:21.922+01:00

Ok, everybody made speculations about the meaning of the F in F-theory. Possibly the most accepted one was that it was due to Cumrumm Va(F)a. But an article appearing now in arxiv has shown it's real origin. The authors of the article are Adil Belha and Leila Medari. It is titled "Superstrings, Phenomenology and F-theory". the abstract reads: We give brief ideas on building gauge models in

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-16841423347389121552009-12-25T20:11:00.002+01:002009-12-25T21:03:54.881+01:00

I have been disucisong in my other (and in the miguis forum) the proposal of Crane to use a black hole as an starship impulsor, bases on his arxiv article: ARE BLACK HOLE STARSHIPS POSSIBLE?. You can read (if you understand spanish) the three post about the suject: 1 , 2 and 3. While discusing that papers I have ben reading in wikipedia about it's litle brother, the Unruh effect. As explained

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com5tag:blogger.com,1999:blog-34983191.post-84338356063619591812009-12-17T23:48:00.009+01:002009-12-21T07:52:34.422+01:00

Ok, a litle bit late, but still something is going on: Fermilab webcast in dark matter CDMSresults Or, if you prefer you can watch the other simultaneous conference: http://www-group.slac.stanford.edu/kipac/cdms_live.html As I am posting late just tell that the main announcement has been already made, two events. That means not a definitive discovering, because of statistical considerations, but

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-24553770491378797312009-12-08T09:48:00.001+01:002009-12-08T09:55:29.783+01:00

Pues si, pues sí. La famosa materia oscura que forma el noventa y tantos por ciento de la masa del universo cuya presencia se infiere por el comportamiento de la materia visible pero de la que no había evidencia directa parece que al final ha sido descubierta en uno de los numerosos experimentos de laboratorio que actualmente se dedican a su búsqueda.En realidad hay un grupo experimental italiano

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-36659615562140356332009-11-24T09:42:00.007+01:002009-11-26T08:26:35.232+01:00

Había escrito, hace ya tiempo, una entrada sobre supersimetría, esta. Continuo el tema introduciendo una realización de dicha supersimetría en términos de un lagrangiano sencillo, lo que se conoce como el modelo de Wess-Zumino. Quien no tenga muy recientes sus conocimientos de teoría cuántica de campos, y en particular los tipos posibles de spinores, puede leer sobre ello en esta entrada de mi

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-7940967917306858752009-10-31T13:01:00.004+01:002009-10-31T17:41:07.328+01:00

In the previous post I had presented the multiverse in a way that made it look almost innocuous. As I have said a few times in this blog I had heard about how the landscape (existence of a large number of vacua) in string theory made it unavailable to make predictions. Despite it the actual articles I had read didn't give to me that impression, so I suspected that I was missing something, the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com6tag:blogger.com,1999:blog-34983191.post-48821911444539175162009-10-17T08:24:00.007+02:002009-10-17T10:16:20.515+02:00

Universe or multiverse?Recently there has been some peak of comments on the blogosphere about the multiverse, partially because of a new article by Linde and Vanchury titled How many universe are in the multiverse?. But the battle against the multiverse, and it's buddy's, the anthropic principle and the string landscape are not new at all. Peter Woit is a championship of that cause. I have

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-64098320341825201412009-09-28T08:17:00.004+02:002009-09-29T19:14:34.740+02:00

The arxiv blog took notice of an article about the possible existence ofo experimental evidence of the collision of universes. You can read it here. For those people who has read the conventional cosmological sceneries, that is, a FRW type cosmology, slightly corrected by a very tiny cosmological constant and an early period of inflation the idea of many universes could sound to them very

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-38569962085880142562009-08-13T08:47:00.002+02:002009-08-13T10:15:19.552+02:00

Summertime, holidays, nothing important going on, isn't it? Maybe, but in my opinion some recent papers on arxiv are interesting. I am going to begin by CYBERsusy. The name can suggest some SF novel cyberpunk heroine. But not. It is an acronym for 'CohomologicallY Broken Effective Retro SUperSYmmetry'. The article is titled A new mechanism for supersymmetry breakingin the Supersymmetric Standard

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-28040812172481262432009-08-04T10:29:00.003+02:002009-08-04T13:29:52.480+02:00

At last the pdf articles of Matti pitkanen about topological geometrodynamics have been uploaded to vixra. If someone wants to beguin he would read Topological Geometrodynamics: Overview. Advise, despite the "overview" word in the title that pdf has 1000+ pages. There are many other papers that the reader can find by himself in vixra. I am aware that TGD is considered crackpot. For example Lubos

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com5tag:blogger.com,1999:blog-34983191.post-71321216595630828472009-07-28T09:28:00.002+02:002009-07-28T10:02:16.318+02:00

I had said that I wanted an easy way to use latex on blogspot. Untill now I was using an external mimetex server and using the html img tag with the url of the mimetex cg and latex code in it. The idea was to create some kind of customized tag that would write the html code. That has too good points. On one hand it makes the edition of the post easier. On the other if the mimetex cg is changed

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com63tag:blogger.com,1999:blog-34983191.post-62077495710465223582009-07-13T10:37:00.006+02:002009-07-13T19:56:45.582+02:00

This year the annual conference in string theory, celebrated at Roma, has not had an internet live TV broadcast as it happened the last year. Because of that reason I didn't do a post about the topic. I have waited until the slides where out and I could have read some of them. The slides of conferences, if they are detailed enough, are a good thing because they are addressed to non specialists in

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-78626384880943778942009-07-09T08:30:00.007+02:002009-07-10T00:08:12.871+02:00

In Kea Monad/Marni Dee Sheppeard blog there has been recently a few entries about the freedom to publish scientific results. As a result Tomasso Dorigo suggested her a bizarre idea. s a result of comments exchange it resulted into another idea, the birth of a new archive for scientific publication. In a really fast movement a new domain was registered and the site is already available. The name

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com6tag:blogger.com,1999:blog-34983191.post-38933893026183688432009-07-08T11:36:00.000+02:002009-07-08T11:36:40.610+02:00

I have found a few papers that do a good job explaining the basics of F-theory in a relatively easy way. I could have posted them as un update of the previous post on the subject but I think it deserves an small separated post. One paper is : F-theory, GUTs and Chiral Matter. Another one, written by Hackman and Vafa is: From F-theory GUTs to the LHC Also I think that the interested reader would

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-35513232679646168822009-06-26T09:15:00.001+02:002009-06-26T09:29:57.406+02:00

Trantor is a ficticial planet presented in the Isaac Asimov series of books about the foundation. It is the centrer of a galactic imperia. In that universe the king of sciences is psicohistory. By that name is referred a mathemathical model of human societies with detailed qualitative predictive power. Physics has become an obsolete discipline that had dead of success long time ago. Supposedly it

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com5tag:blogger.com,1999:blog-34983191.post-62969159459174371812009-06-04T11:06:00.004+02:002009-06-07T12:32:11.174+02:00

Yesterday the number of visits to this blog had a major increase. Most of the traffic came from this post in Miguis web/blog. The post was a translation to Spanish of an article in new scientist about the good points of string theory. I had seen a discussion of that article in Lubos blog, concretely here. Well, that article comes to say that string theory is nowadays a good theory because it´s

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-73469899749204751632009-06-01T08:28:00.006+02:002009-06-11T09:27:47.376+02:00

As I said in the other post, and not for the first time, I don't take cosmology too seriously. I find that there are many uncertainties in the observed data and also in the interpretations. Because of that I hadn't bothered to think too much about that questions. In the last post Kea sugested me to read the Louise Riofrio theory, which resulted to be a version of the VSL (variable speeds of

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com5tag:blogger.com,1999:blog-34983191.post-72249137798784468892009-05-25T10:09:00.002+02:002009-05-25T10:31:24.165+02:00

I had said it before, but a new article, well, in fact two of them, almost consecutives, in arxiv, commented in the arxiv blog, brings again alive the question. My point was to state that although cosmology is a legitimate topic, and that it has seen a fructiferous interplay with particle physic(in, for example, the BBN-big bang nucleosynthesis) cosmological observations are subject to many

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-42958533890240515362009-05-14T10:57:00.008+02:002009-06-04T13:22:35.340+02:00

After an intensive training in algebraic geometry and the reading of the use of type II-B/F-theory in cosmology (KKLT, moduli stabilization and all that) I tried to do a direct attack to the two papers that initiated the F-theory revolution. I had read generic aspects of them in the Lubos and Distler's blogs (well, Distler is actually disappeared and only put an entry about the first paper, this)

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com4tag:blogger.com,1999:blog-34983191.post-88515367454913481042009-04-26T08:52:00.002+02:002009-04-26T11:10:22.113+02:00

Firs a clarification about the title. Most people know who Einstein or Galois are, but maybe not so many will know Margalef. He is an Spanish ecologist who begun his career as a self educated amateur and ended up with a tenure. I choose him because I needed a somewhat Spanish equivalent of the other two personalities. All those people share a common point. They were brilliant scientifcs (Einstein

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com4tag:blogger.com,1999:blog-34983191.post-88629438979868285932009-04-22T09:56:00.003+02:002009-04-22T10:36:08.032+02:00

This month, April 2009, the Spanish edition of Scientific American(investigación y ciencia)has an article about naked singularities (the English version was dated on February). The author, Pankaj S. Joshi, seems to be an total expert in the subject (a common issue in Scientific American)and has a recent book- from 2008- about the particular, Gravitational Collapse and Spacetime Singularities. I

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-24742087602329645252009-04-13T10:13:00.006+02:002009-04-13T20:03:31.087+02:00

I have mentioned many approaches to quantum gravity, other than string theory, in this blog. Besides LQG none of them has had major success in attracting people to do research in it. Now, at least it seems so, there is a new option, the so called Quantum Gravity at a Lifshitz Point initiated by Peter Horava, a well known string theorist (remember the Horawa-Witten model of heterotic string

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-51357512436677480652009-02-24T19:37:00.003+01:002009-02-24T20:44:20.283+01:00

2003 probably was the bes yer for LQG. It was published a relatively short paper (authored by Rovelli) that presented the basics of the canonical LQG. It stated the result of quantization of the area operator, related it to the idea of a minimal lenthg and, and this is the important point, stated that it implied an experimental prediction: "Vacuum light speed depends on it´s frequency". The paper

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-37793282266392189192009-02-16T06:35:00.005+01:002009-02-16T13:14:19.720+01:00

I have mentioned previously in this blog that I was studying algebraic geometry. O.K. I have concluded my first phase of study and it is time to tell something about it. Algebraic geometry is a very broad topic with different possible approaches and epochs of development. Most traditional courses/books of initiation on the subject go through the algebraic approach. As the name suggests there is a

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com9tag:blogger.com,1999:blog-34983191.post-89806763485682985412009-02-08T09:19:00.005+01:002009-02-08T12:38:37.758+01:00

The pioneer anomaly is a rather well established phenomena wichs is still lacking a satisfactory explanation. The Spanish physicist Antonio F. Rañada, well known in his country by his textbook about classic dynamics, and also by a semi divulgative book of introduction to physics (I would add that his theory of topological treatment of electromagnetism, elaborated in collaboration with Jose Luis

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-3545523566923832482009-01-09T04:34:00.002+01:002009-01-09T10:27:11.423+01:00

There are a bunch of things that I would like to post about, but I prefer to take a bit of time to present them in the best possible way. In the meantime I am going to leave links to some review articles. Of course one always go to the string wiki, or search for them in arxiv, but anyway Ill link them. The first one is this. It is a "pedestrian" introduction to the use of the ADS/CFT

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-33889978632277011612008-12-24T10:57:00.002+01:002008-12-24T11:12:18.882+01:00

Today in Arxiv it hs appeared the following paper: A solution manual for Polchinski's "String Theory" The name says it all. The abstrac dissipates any possible dude: We present detailed solutions to 81 of the 202 problems in J. Polchinski's two-volume textbook "String Theory". Also I find interesting the announcement of Tommaso Dorigo in his blog about an upper limit on the mass of the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-2838214984159648602008-12-15T06:05:00.006+01:002008-12-15T08:40:58.589+01:00

Status of Superstring and M-theoryIf someone is interested in getting an idea of the status of string theory today, in a readable form for non specialists, I seriously recommend this paper by John Schwarz Status of Superstring and M-theory. It begins with an introduction to the very subject of string theory, explaining the basic of string theory. It explains in more detail than usual the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-81526527184900148772008-11-18T06:50:00.004+01:002008-12-02T05:21:32.226+01:00

At least some readers of this blog will read some of the links, and also other blogs (and phorums) not linked here. If so it is very probable that they will already know about the fqxi foundation and it´s content about time nature. The actual webpage of the essay is this . The content, or at least many of the papers appeared when he id the post, has been judged by Jonh Baez, in a post in the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-27558648799793205132008-10-31T19:18:00.001+01:002008-10-31T19:18:58.404+01:00

Dos papers salieron ayer dando señales claras de nueva física. De un lado anlizando los datos del satélite PAMELA se ha confirmado un exceso de positrones en los rayos cósmicos respecto a lo esperado según los modelos convencionales.Para explicarlo se sugieren modelos basados en producción de positrones basados en ciertos tipos de materia oscura como puede leerse en este paper: http://arxiv.org/

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-89194078898319261392008-10-29T05:02:00.008+01:002008-12-09T06:24:29.888+01:00

I keep reading Physicsforums, specially the beyond the standard model forum. Recently there was a discussion about a new proposal appeared in arxiv arguing that maybe gravity wouldn’t need to be quantized after all.The paper in question, authored by Stephen Boughn is this.It is a very clear paper where the usual assumptions are reviewed. As is commonly known we actually have a quantum theory, the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-325079517824887962008-09-20T06:05:00.002+02:002008-09-20T09:10:34.105+02:00

Afther listenign almost all the confrences of strings 2008 that I mentioned in the earlier post I had to make a break into blogging because of a few diferent reasons (computer virus, preparing people for september exams and so on). In the while I have ahd time to read a few papers and a few books, the books not mainly about quantum gravity related things. In all this time the most interesting

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com4tag:blogger.com,1999:blog-34983191.post-43782702874276931762008-08-18T10:14:00.001+02:002008-08-18T13:54:58.382+02:00

¿Alguna vez te has planteado asistir en directo a un congreso sobre física de cuerdas? Ahora puedes, al menos virtualmente: P.S. Podeis ver los horarios, con las diversas conferencias aquí Lubos esta actualizando su blog con comentarios sobre las diversas conferencias (a la fecha de escribir este post script van 3). Podeis seguirlo en esta entrada Yo por mi parte intentaré comentar alguna cosa,

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-38096392985462232312008-08-09T07:13:00.010+02:002009-12-25T21:04:36.641+01:00

Un entrada "ligerita", para que no se quede esto abandonado demasiado tiempo. La teoria cuántica de campos ordinaria se formula en espacios planos, en partícular en el espacio de Minkowsky. Se empieza explicando la teoria de campos libres, interesante para explicar el concepto de vacio y de espacio de Fock. En cuántica ordinaria (no relativista) se suele hacer teoria cuántica de una partícula. Y

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-14101972545683864032008-07-14T07:42:00.003+02:002008-07-18T05:29:15.274+02:00

Like many physicist I am a reader of science fiction. String theory is not a topic which is too broadly covered in SF, and, anyway, it is not covered too properly. For example, it could be that the author limits to cite the words "calaby-yau" as some kind of manra. Even thought there is one particular novel, writen in the eiguthies, where there was a fine usage of string theory. There an alien

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-25732412038926495372008-06-15T09:58:00.000+02:002008-06-16T11:47:32.942+02:00

It could be easy to suppose that following some selected blogs, and reading discussions in the appropriate forums one is aware of "what´s going on" in quantum gravity related issues. Well, the Ian Malcon´s law, you know, "98 % of what you believe is false" strikes again. If you follow the link´s sections of some of the most well known blogs (Motl, Distler, Woits, etc) you find that many of the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com2tag:blogger.com,1999:blog-34983191.post-36459160155872759472008-05-25T04:23:00.007+02:002008-06-02T07:04:42.823+02:00

The LCH is next to open. Hopefully supersymmetry and the Higgs boson will be found. But there are more possible things that we can find there. The recent Planck 2008 congress was devoted to that topic. You can see blog entries covering that in the Dmitry (non equilibrium phenomena) blog, concretely this entry, and previous ones (ok, the entry with the interview to Polyakov is not about Planck

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-72602549081159501732008-05-18T07:56:00.002+02:002008-05-19T10:52:07.954+02:00

A few days ago a friend of mine, graduate theoretical physician, but not an active physician nowadays, and an ocasional reader of this blog,let me know of a new in the media versing about a resolution of the "black hole information paradox". The new was published in many webs, for example here. By the same time a thread was opened in physics phorums about the topic, concretelly Physicists

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-19667742174768947172008-05-13T06:39:00.002+02:002008-05-13T09:26:29.277+02:00

A través del excelente blog física en la ciencia ficción llegué a otro blog, la bella teoria. Supongo, no lo sé con certea, que eso de "la bella teoria" debería ir por la teoria de cuerdas, que en su momento alguna gente consideró matemáticamente bella y elegante. En todo caso en el blog ví que se trataban con cierta frecuencia temas sobre teoria de cuerdas (aunque no exclusivamente). También

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com4tag:blogger.com,1999:blog-34983191.post-38562155253424236512008-04-29T09:21:00.005+02:002008-05-01T21:05:02.213+02:00

The first oe paper is LOCALLY FINITE MODEL FOR GRAVITY written by Gerard ’t Hooft. If by some casual you dont know who ´t hoof is just to say that he has a nobel prize by proving that the gauge theories, wich are the basic ingredient, of the standard model, are renormalizable. A few physicists I know consider him the last greater phyisicist (Steven Weinberg would be considered slighly earlier in

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-22832757104212937472008-04-26T20:40:00.000+02:002008-04-27T18:08:57.013+02:00

As announced I have created an aditional blog inwordpress. The actual url is http://freelancescience.wordpress.com/. The idea is to keep this blog for quantum gravity related stuf and the other for diferent aspects of physics, math, and, ocasionally, another sciences. A separate interest is to see how well it works the LaTeX functionality of wordpress. If it works fine, and blogspot refuses to

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-74391599478860115202008-04-04T15:39:00.002+02:002008-04-04T16:22:10.302+02:00

The very recent mounths seem to have brought great news for string theory. I´ll write in this post a brief guide to the relevant papers. The first, cronologically, is this paper by Beasley, Heckman and Vafa. It is a paper where, for the first time, it is addressed the task of constructing phenomenology from F-theory. A second one is announced where the program started in thiw will be concluded.

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-80402994051840605452008-03-18T09:28:00.000+01:002008-03-20T09:55:36.798+01:00

I have writen relatively few (here and in forums) in the las times. This doesn´t mean that I would have somewhatleft the physici, quite on the contrary. Cronologicaly the first reason to stop me writng was to do a sistematic reading of Jackes Distler´s blog. That gave me a partial idea of what had been hapening in string theory and quantum gravity in general in the very last years. One of the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-6196844440873875472008-02-19T11:46:00.000+01:002008-02-19T11:47:14.520+01:00

Esta pregunta tiene una respuesta fácil, porque experimentalmente es lo que se observa. La problemática surge dentro del marco de las teorias de cuerdas, que tienen cómo requisito (salvo en versiones harto polémicas cómo las cuerdas de Liouville u otras también bastante discutibles, cómo las cuerdas supercríticas) que esten formuladas en 10 (u 11 para la teoria M) dimensiones. Aquí he hablado de

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com4tag:blogger.com,1999:blog-34983191.post-3233962808325715702008-01-29T10:01:00.000+01:002008-02-09T10:54:13.128+01:00

El año pasado ha surgido una nueva moda en los mundos de la físia de altas energías, la teroia de las no-partículas. El responsable de esta teoria es Howard T. Georgi, un muy conocido y respetado teórico cuya mayor contribucioin a la física, hasta el momento, fué el modelo de unificación para las fuerzas electrodébiles y la cromodinámica cuántica (es decir, todas las conocdias menos la gravedad)

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-63206183151938981682007-12-05T05:02:00.000+01:002007-12-08T09:52:40.292+01:00

I have, at last, readed the following article of Leonard Suskind on the antropic landscape: http://arXiv.org/hep-th/0302219 v1 Before briefly discusing it I will mention that I have also beeing reading the chpater on cosmology of dinés book "supersymmetry and string theory" and some stuff on blogs and forums about cosmology. I must say first that a few years ago (maybe a decade) the view of

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-38981591210109601562007-11-24T20:20:00.000+01:002007-11-24T22:15:41.675+01:00

I am almost sure that if some high end professional of string theory hs readed the previous entry vill have renewed his very bad thoughts about the physics blogosphere. If, instead, he would have readed the post about Horava-Witten theory and brane univereses I guess taht he instead will have felt more confortable. This is because the post of topology vs group theory was speculative, probably too

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-52348302024090016822007-11-24T09:35:00.001+01:002008-06-01T20:22:38.646+02:00

I have said in some ocations that I dont´t like too much group theory, and that I prefer to study topology. I am going to try to explain a litle bit about it. One of them is pureley mathemathical, I prefer to study things like homology, cohomology, sheaves, spectral sequences, cobordism, morse theory, K-theory and mostly all the topology in the world than group theory. Group theory, and it´s

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-68445227095030083462007-11-22T05:25:00.001+01:002007-11-23T09:15:05.754+01:00

I was aware of the existence of this theory since the post of Lisi in the Sabbines Hosfander "inspirational series". There he stated that "he was cooking a theory to kick the string theory ass" (or something quite similar). Not too surprisingly in the comments sectionhe was quilified by Lubos Motl as an crank. I am not a terrible fan of group theory and this proposal of ToE (theory of everything

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-11651786981103959922007-11-08T06:51:00.000+01:002007-11-14T20:18:11.218+01:00

I bet that among the "vocabulary" of string theory the two that more broadly have expanded in the layman are "Calabi-Yau" and "warped (or brane world) universes". I have already made (in Spanish) a brie introduction to compactifications and Calabi-Yaus. Now I am going to talk about the warped universes and related questions. I dón´t know the details of the history, but the "heuristic" aspects

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-53943888989135256392007-11-07T04:45:00.002+01:002008-05-19T16:38:58.300+02:00

My intention for this post was to make an exposition of Horava-Witten theory and the phenomenological and cosmological theories related to them (brane universes, ekptyroptic, etc). But a confluence of factors has decided me to make a brief post about a diferent topic. In a previous entry I talked about conformal gravity. That was a nice theory which could presumably reproduce general relativity

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-88456432526888790562007-11-06T04:59:00.000+01:002007-11-06T16:02:08.685+01:00

I have changed the name of the blog to somewhat most "stringy" (that is, the possible dimensions of spacetiem in string theories). In fact it also was the usual califications I used to have in exams in a far past (and indded in the very last exam that I did, well, almost), that is, upper the maximum, but unfortunatelly I stopped to get that notes when they could have been more usefull. Anyway,

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-21657939382229724082007-10-17T20:59:00.000+02:002007-10-20T09:36:41.793+02:00

Recordemos, las supercuerdas convencionales (las únicas de la que voy a hablar) se formulan en 10 dimensiones. Cómo el universo observado tiene la indecencia de no dar signo evidente de más de 4 hay que hacer algo para obtenerlo. Cómo bien explica el amigo Green lo que se hace es explotar la vieja teoría de Kalua-Klein de compactificar las dimensiones. Además uno saca la ventaja de que las

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-5963797489886106262007-10-16T02:01:00.000+02:002007-10-17T13:23:04.835+02:00

Fist of all to advise the possible readers that despite the name of the entry this post will, at least partially, be kept on the topic of quantum gravity related arena to which this blog is devoted, concretelly to the problem of the colapse of the wave function and some purposed solutions, including "quantum conscence" theories. I certainly could write about many other non "quantum gravity"

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com5tag:blogger.com,1999:blog-34983191.post-74135288649834466292007-10-07T10:27:00.000+02:002007-10-15T07:21:52.405+02:00

While I orginize ideas to post about more conventional ideas in physics (or science in general)I am goint to post today about topological geometrodynamics. Ther first time I got knowledge of these thoery was as a consecuence of seraching for p-adic numbers in the net. If I don´t remember bad I did that rsearch because I was triying to understand some chapters in that monument to abstract

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com23tag:blogger.com,1999:blog-34983191.post-34670596533841704072007-10-04T13:25:00.000+02:002007-10-05T13:16:14.096+02:00

I had a few entries in this blog wondering about some unnaturallness that i find in string theory. On the other side I am aware about what some people in the string theory comunity think about LQG, so I have decided to make a post about why someone could worry about LQG nowaday (or why not). One important thing is your academic enviroment. One of my teachers (probably the best in the field of

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-6435608781765181402007-08-31T11:27:00.001+02:002008-06-01T20:19:55.175+02:00

The most relevant new of this month was, probably, the announcement of the MAGIC discovery of indications of the possibility that light speed could depend on its frequency. The relevant paper is this. it has been discussed in some blogs (Lubos, Peter Woit, Sabine) and some forums (for example physics forums or, in Spanish, migui´s forum. See the links of these blog to search them if you are

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-72799956625033064512007-08-16T06:40:00.000+02:002007-08-17T22:32:38.940+02:00

Untill now most of the posts inthese blog have been expository. It is time for an expeculative one. I´ll try to give a few musings about the role of math in modern physic. Before anything else I must say that it is totally ridiculous that while theoretical physics goes into more abstract mathemathics graduate programs of the universities goes towards less level in maths in favour of informatic

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-29116902624344145412007-08-07T06:24:00.000+02:002007-08-09T10:35:26.317+02:00

In a recent post about the "brane forest" I said that although in type II strings, which are closed strings, there are d-branes, and play a very important role, I had not seen an explicit construction of them. After all in open string theory there is an easy way to see the appearance of d-branes, they are hyperplanes at which the extremes of open string can end. But, clearly, the same image

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-14275802272860585402007-07-31T08:39:00.000+02:002007-08-01T10:36:43.026+02:00

As most peoople who is nowadays interested in quantum theories of gravity knows, there is in the internet something called "string wars". These "wars" consist on a dialectic batlle betwen some string theorists, with Lubos Motl as the main contendient vs some people who claim that string theory is dead (mainly Peter Woit) because of it´s lack of experimentally falsifiable predictions and other

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com18tag:blogger.com,1999:blog-34983191.post-72633485334199866842007-07-17T08:04:00.001+02:002008-05-19T16:37:31.697+02:00

I have just seen in physics forums the following paper:Conformal Gravity Challenges String Theory I had no previous knoledge of these theory and now I have no time to search in google references for it so I just expose it without any claim about how good or flawed it could be. The author, Philip D. Manhein, semmengly a refuted cosmologist, reviews the genesis of general relativity and isolates

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-68522749711500644312007-07-12T18:01:00.000+02:002007-07-12T18:02:18.360+02:00

Estos días he estado mirando cómo anuncié, entre otras cosas string field theory. Voy a intentar dar una idea muy superficial de en que consiste y ya expondré los detalles en algún otro momento. En un post anterior expuse con un cierto detalle la parte clásica de la cuerda bosónica, escribiendo su lagrangiano y explicando algunas de sus características (invarianzas y demás). Cómo expliqué allí

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-72956944438135750642007-07-03T05:22:00.000+02:002007-07-03T09:14:45.800+02:00

First of all a quick clarification about the use of two diferents languages, english and spanish, in these blog. Initially I had the intention of using only english, but my participation of some spanish forums about physics derived in posts which I find could be interesting here (in a more complete form that the original ones in the forums). Also in spanish there is less material available about

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-8722870610398070532007-06-24T07:38:00.000+02:002007-06-25T04:44:45.657+02:00

En este journal se ha hablado mucho sobre la teoría de cuerdas, pero, sin embargo, no se ha hecho nínguna exposicion formal de la misma, Bien, es tiempo ya de ser un poco mas precisos respecto a la teoria de cuerdas,Empezamos por lo más sencillo, explicar que es una cuerda dentro de esta teoria. Bien, en realidad es la cosa mas sencilla del mundo, una cuerda (bosónica), matemáticamente, es una

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com3tag:blogger.com,1999:blog-34983191.post-68634394700854296582007-06-08T23:33:00.000+02:002007-06-08T23:37:46.501+02:00

¿Que es esto de la geometría no conmutativa? La respuesta varía un poco dependiendo a quien preguntes, un matemático o un físico. Un matemático dirá algo así cómo que es algo relacionado con la geometría algebraica y enseguida te atacará con un montón de álgebra abstracta. Un físico empezará por mencionar la mecánica cuántica (que raro xD) y te dirá algo del estilo: "El principio de

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-73395690793259873282007-05-27T19:48:00.000+02:002007-05-28T21:09:15.783+02:00

Habíamos visto por encima el formalismo ADM. Vamos a mantener la misma foliación del espacio-tiempo que para evitar confusiones de notación aquí denoto por Et=MxR. Dejo una imagen que pueda aclarar un poco esto de las foliaciones, que es importante visualizarlo para entender la parte clásica de estas teorias: Doy ahora también mas detalles de la descomposición de los vectores tangentes a cada

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-67380532058397368912007-05-12T20:01:00.000+02:002007-05-14T08:01:28.078+02:00

He hablado por aquí de la loop quantum gravity pero hasta ahora no había explicado nada de ella. A raíz de empezar a participar en un foro de CF, www.sedice.com, me encontré con que me pidieron un post sobre el tema. He aquí la primera parte del mismo (ligeramente retocada). Aviso, en el post se repiten algunas cosas que ya he explicado, y mas extensamente aquí, pero creo que no viene mal tenerlo

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-89682521228336521722007-03-26T09:39:00.000+02:002007-03-26T14:35:49.025+02:00

Nivel: Doctorado de física teórica (o nivel avanzado de licenciatura)Mucho se ha hablado de supercuerdas. Esta palabra consta de dos partes. La parte de "cuerdas" más o menos es algo que todo el mundo puede entender en el sentido de que todo el mundo tiene la idea intuitiva de lo que es una cuerda. La parte "rara" es la de super. El prefijo "super" se usó mucho en física en una época. Los casos

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-77068689790043220192007-03-17T21:23:00.000+01:002007-03-26T14:37:14.346+02:00

Nivel:Doctorado de física teórica (o nivel avanzado de licenciatura)Voy a exponer cómo la teoria clásica del electromagnetismo puedes surgir de las dimensiones adicionales . Es lo que se conoce como el modelo de Kaluza allá por el 1919, con la RG recién salidita del horno.Antes de ello hablar un poco del electromagnetismo en si mismo. La idea es sencilla, existen en la naturaleza unos campos E y

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com1tag:blogger.com,1999:blog-34983191.post-14653327507538268172006-12-27T09:10:00.000+01:002007-03-26T13:48:32.276+02:00

Level:Speculative physics, doctorate (or advanced graduate) levelI have been keeping studiying the Clifford V. Jonhson book (D-Branes) and I gues I hvae a good understanding of the first six chapters. Specially I think I, at last, begin to understand the subleties of D-brane theory.I have made a bit of crosscheckingof my understanding with the first chapters on string theory of the book of Tomás

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-1166861950347321912006-12-23T09:08:00.000+01:002007-03-25T20:02:43.208+02:00

It has been a few weeks that i dónt publish anything. I have been learning a few buch of things while.I had posted in these blog some doubts about the foundations of string theory. I also posted some of them in physics forums. If you don´t want to push the link I´ll give you some of the answers I got:Dmystifier:here is no such thing as constituent points. A string can decay or snap only into

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-1164009941458951282006-11-20T07:48:00.000+01:002006-11-20T09:05:41.850+01:00

I have these blog somewhat stopped while I am updating my knoledege in string theory. My previous background in the field came mainly from three books. The Lüst- Theisen one: "lectures on String theory" from the series "lectures notes in physis of Springer Verlag, "Quantumf field theory of point particles and strings" by Brian Hatfield" and "Strings theory and M-Theory" from Micho Kaku. For the

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com12tag:blogger.com,1999:blog-34983191.post-1160396710069813992006-10-09T14:15:00.000+02:002007-03-25T20:02:13.079+02:00

Well, apart of these ontological questions we always could listen to Feyman and go with the "don´t think, calculate" premise. But, can we? The fundamental calculational tool in string theory is the polyakov path integral. If you read the correponding chpaters in the string books they aregue that one virtue of string theory if that you don´t need so many feyman diagrams and taht you basically need

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-1159188043725062002006-09-25T14:05:00.000+02:002007-03-25T20:01:27.395+02:00

There are considerable amounts of blogs which attack string theory.Some of the argued reasons against it are things like: "they require additional non-observed dimensions", "they don’t make predictions and so they are not refutable", et, etc, you can see the "not even wrong" blog to find many of them.I particularly have a problem with string theory far before all these questions even appear in

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0tag:blogger.com,1999:blog-34983191.post-1159173197242059152006-09-25T10:27:00.000+02:002006-09-29T14:48:42.876+02:00

These is intended as a blog mainly centered in diferent aproachs to quantum gravity, that is, string theory and loop quantum gravity and maybe others. Also it will paid some atention to the historical development of the subject.I don´t claim to be an expert in none of them. That makes me feel freeand to not be tied to any of the contending theories.

Javierhttp://www.blogger.com/profile/17845977289427117418noreply@blogger.com0