Cosmo-torun

cosmo-torun@cosmo.torun.pl

328 discussions

Re: information request
by Boud Roukema 04 Dec '03

04 Dec '03

[pl] Witam - kolegy interesowane na tym dyskusji, proszę do http://www.astro.uni.torun.pl/sympa/cosmo-media/ Chciałbym że dyskusja jest publiczna, ale nie chcę spamować w po francusku... ;) [fr] Cher David, (Tu peux m'appeler Boud - mes travaux sont valables ou erronés indépendamment de mes titres officiels. Et j'en ai marre du vousvoyage, c'est pire encore en polonais avec "Monsieur pense-t-il ?"...) On Tue, 2 Dec 2003, dlarousserie wrote: > I am a french journalist working in a scientific magazine called > Sciences et Avenir (about 250 000 ex. monthly). I am writing a > paper on the shape of the universe ; Because of the recent paper Génial ! :))) > from Luminet et al. in Nature (9 ocotber 2003). I know that you > were, but perhaps are still, involved in this field. Then I have a > few questions. Je m'y intéresse toujours :)). Il y a maintenant une équipe de cosmologie à Toruń (Pologne) en train de se former, et la topologie cosmique est une de nos priorités. > In 1997, you have annouced that three galaxy cluster were in fact the same. Pas tout à fait. Alastair Edge et moi avons annoncé que trois amas de galaxies se trouvaient localisés dans l'espace d'une façon qui donnent à penser qu'ils soient trois images topologiques d'un seul amas. En traitant cette idée comme *hypothèse de travail*, Alastair Edge, Stanisław Bajtlik et moi avons essayé de la réfuter, vu qu'une quelconque hypothèse de topologie cosmique (comme celle de Luminet et al. dans Nature) devrait être solidement testée empiriquement avant qu'elle puisse être prise comme élément clé de la cosmologie moderne. * http://fr.arxiv.org/abs/astro-ph/9706166 - Roukema, Edge - premier article sur l'hypothèse spécifique * http://fr.arxiv.org/abs/astro-ph/9903038 - Roukema, Bajtlik - analyse photométrique des cartes de ciel - une tentative d'identifier des galaxies individuelles lentillées entre les deux images de l'amas à grand redshift, et ainsi d'en déduire leurs vitesses dans le plan du ciel, donne un résultat raisonnable (nous espérions trouver une incohérence et ainsi réfuter l'hypothèse) * http://fr.arxiv.org/abs/astro-ph/9910272 - Roukema - analyse du rayonnement de fond cosmologique (COBE) - hypothèse réfutée à une confiance de 94% (ce qui n'est pas très fort), à condition d'ignorer l'effet d'une constante cosmologique non-nulle. Or, aujourd'hui, quasiment tous les observateurs (sauf l'équiipe d'Alain Blanchard à Toulouse ;), et les partisans du modèle steady state comme Jayant Narlikar, Jean-Claude Pecker, ...) sont convaincus que la constante cosmologique est non-nulle. > Is it right ? Did you received confirmation ? La réponse courte est : « Je ne sais pas. » Je préfère distinguer mon intuition des calculs clairs et nets. Mon *intuition* est que cette hypothèse est probablement incohérente avec les observations du fond diffus cosmologique du satellite WMAP, et je travaille en priorité sur d'autres hypothèses. Or, mon intuition n'est pas une preuve qui enterre définitivement l'hypothèse. Lors de ma visite chez nous, à l'Obs de P-Meudon, Dominique Proust (maintenant dans le département « GePi » de l'Obs P-M) nous a aidé dans la préparation de demandes de temps aux télescopes au Chili et à l'Hawaï pour tester l'hypothèse. Or, nous n'avons jamais reçu de réponse positive des comités d'allocation de temps... :( Ce qui ne dit pas que notre hypothèse soit la bonne, elle dit plutôt qu'elle n'entre pas dans la pensée de productivisme à court terme. > What was the name of the three clusters ? Les trois amas sont: * l'amas de Coma * RX J1347-1145 * CL 09104+4109 Vous pourriez profiter des articles publiés librement (voir le fr.arXiv.org ci-dessus). > Do yo know if someone has observed the same similarity in galaxy > clusters or another objects ? Le travail le plus proche que je connais est celui de G.I. Gomero, mais je ne trouve plus de version publique de ces articles. En tous les cas, les résumés sont toujours publiques: * http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?bibcode=2003CQGra..20.4775G * http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?bibcode=2002IJMPA..17.4281G > What is your opinion on the work from Luminet et al. ? Voir http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/CommuniqueDePress… pour le point de vue de notre équipe. Je n'ai pas de monopole sur la sagesse, mieux regarder nos points de vue intégrées (en autres mots, mes propres points de vue corrigés par les critiques de mes collègues). > Do you have your own "shape" of the universe ? I mean, how do you > see our Universe ? Tout simplement je ne sais pas quelle est la forme de l'Univers. Je voudrais bien la savoir, et c'est pour cette raison que j'y travaille avec mes collègues... > When I speak about this subject, people ask me what is the interest >of such a research. What can I answer ? Why is it interesting to know >the shape of the universe ? Du point de vue des Lumières, l'intérêt principal est culturel : (quasiment) tout le monde a envie de comprendre et de savoir. Savoir quel est la forme de l'objet dans lequel nous vivons est fondamental. Du point de vue mercantile (genre Matra-Hachette-Lagardère, Messier, Bouygues, etc) et des politiques (genre Osama bin Laden, Jacques Chirac, Tony Blair, Saddam Hussein, Nicolas Sarkozy, George Bush), du point de vue de chacun-pour-soi, l'intérêt est que la recherche fondamentale motivée par la curiosité, sans aucune justification « productiviste » a régulièrement sorti des surprises qui plus tôt ou plus tard sont utilisées pour les buts technologiques. Voilà donc du fric et du pouvoir. Les ordinateurs avec lesquels nous communiquons sont en grande partie le fruit de réflexions sur la nature de la logique même. Mais pensez aussi à la radioactivité, à la relativité restreinte (« la théorie de Poincaré et d'Einstein), à la mécanique quantique, aux lasers, ... Evidemment, comme toute découverte scientifique peut être utilisée dans son application technologique tant pour violer les droits humains ainsi que pour les soutenir (en règle générale), la conséquence des découvertes cosmoloqiues pourraient, éventuellement, être de loin plus dévastateurs que les découvertes de la radioactivité et de la relativité restreinte, plus catastrophiques que les découvertes empiriques dans la psychologie et leur application dans les méthodes de propagande modernes et malheureusement légales et meurtrières, et plus répressives que les méthodes de torture dans les camps de la Guantanamo Bay qui pulvérisent le contenu humain du cerveau tout en gardant le corps en bon état. > What is your own motivation ? Tout simplement, j'ai envie de comprendre l'Univers :). Et les risques que je viens d'énoncer, alors ? J'en les assume. Je suis conscient des risques que je vient d'énoncer, et si les résultats soient catastrophiques, j'aurai ma part de blâme (bien qu'il n'y aurait peut-être pas ni moi ni aucun autre humain pour en parler...). Or, les arguments énergétiques et les mécanismes décisionnels qui permettent quelques éléments de démocratie dans notre société globale suggèrent que le plus grand risque actuel vient de l'Empéreur Bush et son Régent Dick Cheney plutôt que de la communauté des physiciens. Néanmoins, pour que *toutes les sciences et technologies* soient plus gérables par les cityon-ne-s, je suis aussi motivé dans le développement de plus de participation dans la recherche scientifique, les miennes incluses. J'essais de promouvoir la science ouverte, non au sens de mots vides, mais dans le sens de l'usage des technologies de l'internet pour non seulement permettre une participation du genre « les croyants peuvent lire ce que disent les sages » mais pour raccourcir les distances entre les fans et les experts. En jetant un coup d'oeil sur nos pages http://adjani.astro.uni.torun.pl/cosmo tu verrais que je commence en encourageant la transparence de relations entre étudiants (1ère, 2ème et 3ème cycles universitaires) et chercheurs, et j'espère pouvoir développer des logiciels qui peuvent être utilisés au sein s'un système ouvert comme GNU/linux afin que l'utilisateur moyen avec un savoir scientifique de base (niveau bac) puisse en profiter. Certaines parties des travaux astronomiques/cosmologiques sont très ouvertes, d'autres sont à moitié fermés comme certains logiciels « open source » qui non sont pas « libres » au sens du GNU GPL/LPG GNU (http://www.april.org), et encore il y a toujours des données empiriques ou logiciels complêtement fermés. Nous avons encore une longue distance entre nos pratiques actuelles et celles de la communauté GNU/Linux... > Do you think we could answer to this question ? When ? Is the Planck > observer the last hope ? Les prévisions du futur sont très peu fiables dans ce genre de domaine. Mieux regarder dans http://www.bdl.fr pour voir quelles seront les dates d'éclipse en 2007 ou 2008 ou 2010 plutôt que prédire le résultat d'une recherche scientifique de fond. :) > According to you who are the leader in this field ? Je ne crois pas trop au mythe des « stars » dans la recherche. Néanmoins, vu que les chercheurs actifs dans ce domaine qui reçoivent le moins de publicité sont ceux de l'Amérique du Sud et du Japon, pour des raisons nombriliques traditionnelles aux USA et en France, il faut que je vous les disent leurs noms: Helio FAGUNDES, Germán GOMERO (german à ift.unesp.br), M.J. REBOUCAS, et Kaiki Taro INOUE (ex http://fr.arxiv.org/abs/astro-ph/0103158, tinoue à yukawa.kyoto-u.ac.jp) > That's all for this time... N'hésite pas à répondre sur mailto:cosmo-media à astro.uni.torun.pl > Best regards, > > Larousserie David > 00 33 1 55 35 56 27 Bien à vous :) Que le savoir avance ! boud

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IV Torunski Festiwal N .i Sz. (fwd)
by Boud Roukema 04 Dec '03

04 Dec '03

Witam, Andrzej Kus już proponował że zrobimy debat panelowy na tym Festiwał. Widocznie, ktoś w Administracji był bardzo zadowolony z artykuł w Rzeczpospolicie... Niezależny od mediów, zgadzam się że byłoby fajny pomysł zrobić jakiś prezentacja rozmaity punkt widzenia - dla inflacji, dla możliwość mierzyć topologia Wszechświat. Dokładnie format możemy dyskutować kilka dni przed Festiwał, ale chyba potrzebujemy: - tytuł - abstrakt - nazywa kto będzi mówić (ale oczywiści, moźemy zmienić na ostatniu minut, tylko nie będzi Twoja nazywa drukowana na reklama etc.) Tu propozycja: http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/FestiwalNauki2004 Staszek mówił że potrzeba być propozycja do jutrze czw 4 grudnia (jest trochę absurdalny, dać tylko jeden dzień dla decydować, ale nie ma sprawy), więc będę dać jej do Andrzeja Strobela jutro (czw 4 grud) w popołudniu. Oczywiście, ja nie mogę kontrolować co będzie na reklamów ofycjalny, ale chyba w praktyce możesz myśleć w czasie następne kilka miesięce... Proszę poprawiuj ten stron! http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/FestiwalNauki2004 pozd boud > > ---------- Forwarded message ---------- > Date: Wed, 3 Dec 2003 09:50:36 +0100 (CET) > From: Stanislaw Krawczyk <Stanislaw.Krawczyk at astri.uni.torun.pl> > To: staff at astri.uni.torun.pl > Subject: IV Torunski Festiwal N .i Sz. > > Zgodnie z ustaleniami na ostatniej Radzie Centrum bardzo prosze o > skladanie propozycji uczestnictwa w Festiwalu ( tematy prelekcji lub > innych imprez) na ręce pana prof. A. Strobla do dnia 4 grudnia 2003. > Na wyklady zarezerwowana jest wstepnie sala wykladowa w Instytucie Chemii > na Bielanach w kazdym dniu Festiwalu (22-25 kwietnia 2004) w godz. 18-20. > Formularze zgłoszeniowe jak i więcej informacji o przyszłorocznym > festiwalu mozna znalzc na stronie www.festiwal.torun.pl badz w biurze > Centrum Promocji i Informacji UMK (tel. 611 46 57, 611 48 74) > Podobnie jak w roku ubieglym organizowac bedziemy zwiedzanie Centrum i > pokazy nieba przez teleskop i w miare odpowiednich warunkow projekcje > filmow astronomicznych w "letnim kinie". Prosze takze o deklaracje > uczestnictwa w tym rutynowym przedsiewzieciu bezposrednio do mnie > badz do prof. A.Strobla. > Z gory dziekuje za pomoc w promocji naszego Centrum na Festiwalu. > S. Krawczyk >

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Fine structure constant vs. quintessence
by Andrzej Marecki 02 Dec '03

02 Dec '03

NEWSALERT: Thursday, November 27, 2003 @ 1442 GMT --------------------------------------------------------------------- The latest news from Astronomy Now and Spaceflight Now [...] Light signals from quasars seem to indicate that the bond between electrons and protons was weaker in the early universe. Luis Anchordoqui and Haim Goldberg of the Department of Physics at Northeastern University in Boston, Mass., propose that the apparent change in the fine structure constant is coupled to "quintessence." The fine structure constant was measurably weaker ten billion years ago, but as quintessence assumed dominance about eight billion years ago, the force between electrons and protons became stronger and "more constant." http://spaceflightnow.com/news/n0311/25nature/ ----- End of forwarded message from NewsAlert ----- -- Andrzej

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magister course 2003/2004
by Boud Roukema 12 Nov '03

12 Nov '03

Proposal for Supervising Masters (Magister) projects at TCfA for Nov 2003 - Sep 2004 Supervisor: B. Roukema (boud at astro.uni.torun.pl) Number of students: up to 3-4 students is possible Title: Observational Constraints on Cosmological Parameters Description: There are many possible projects which could be done as a master's thesis project, in using publicly available archival data from observational surveys to constrain one or more of the local or global cosmological parameters, either those related to shape (curvature, topology) or maybe also those unrelated to shape ("dark energy"). The precise projects would be chosen in discussion with the masters students during Nov-Dec 2003. One example would be further development and application of the "Dark Energy" software package which has been worked on during the "Shape of the Universe" monograph course: http://www.astro.uni.torun.pl/sympa/shape-univ/ Requirements: - basic knowledge in astronomy, physics, mathematics, computing skills - desire to measure something about the shape of the Universe - willingness both to learn from and to teach others interested in observational cosmology at TCfA - willingness to learn the following practical skills: touch-typing, emacs, \LaTeX, usage of mailing lists and wikis for communication - participation in the "Shape of the Universe" monograph course and/or Bronek Rudak's semester 9 "Kosmologia" course: http://www.ncac.torun.pl/~bronek/KOS.html - nie ma problemu jeśli student magisterowy (jeszcze) nie dobrze mówi po angielsku

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Re: prosba o komentarz
by szajtan odwieczny 03 Nov '03

03 Nov '03

> > > > What I think we can say for sure is that, although we're not sure about > > > > the actual curvature of our obserwable universe, and thus we're not sure > > > > if the space go on and on to infinity, it seems that it's quite sure that > > > > our universe is accelerating (q<0), and from this point of view we can say > > > > that if we send out a probe into the space even at the velocity of light, > > > > it's likely that it will never return regardelss of the the curvature > > > > of the universe, because it just won't overpass the expantion rate of the > > > > universe unless there is some nontrivial topology involved. The Big Crunch > > > > never happens in area where q<0 on Omega_l, Omega_m plane. So from our > > > > point of view we can say the spacetime is infinite if we're thinking in a > > > > > > We can't say "the spacetime is infinite". What you mean is > > > why not ? > > Because "x is infinite" means that > "for every y \in {Real numbers}, x > y". > > If the Universe has positive curvature with curvature radius R_C (and > is a perturbed FLRW model, as we think), then there exists a maximal > length spatial geodesic X_s and a maximal length space-time geodesic > X_st . okok but if we set k=1 the solution of geodesic equation in FLRW metric for distance is something like arcsine function of comoving distance times S(t). So it's closed solution and space is finite. but when additionaly we set for example Omega_l > Omega_cdm then S(t) has no maximum (as is had in closed model with zero cosmological constant) and it grows with time to infinity. hmm it sounds simple ;) however infinity doen't appear anywhere in flormula. What I said was that I think the data are suffucient to say that the photon once sent in some direction will never return no matter what curvature the universe has because of S(t). So from the point of view of that photon the universe will be infinite > Then, there exist y \in {Real numbers} greater than these values and > there are no longer any x in the Universe greater than y. So it's not > infinite. > > > > event horizon accounts for all evolution of expantion according to assumed > > model. if it's less than the curent curvature radius then we won't see the > > probe, if it's bigger we mae but not must see it, for the curvature > > radius is changing in time. > > i'll let you do the calculations here, but they are irrelevant for the > question of infinity. > > > the fundamental nature of the model is that going in space we also move in > > time. > > This is extremely confusing language. What do you mean by "going in > space", "moving in time" and "we"? If you mean there's a second time > variable representing the time variable of a thought experiment, then > it makes sense. Or if you're talking about a physical particle, then > two different time variables are the local (proper) time of the particle > and the cosmological time. > > But it's perfectly possible to imagine comoving space without needing > any time variable to "go" through it (though having a local psychological > time variable is convenient). well, comoving space without remembering of time. how would you describe how it comoves then ? ;) it wouldn't differ from galileo's static space. > > > eg. Imagine that that space is closed, and expands slow enough that > > a photon emited from your flashlight can round it, but as the time passes > > expansion rate mae grow up, event horizon falls, (say cosmological > > constant starts dominate) and the photon won't make it eventually. > > IMHO this is a different theme to the universe being infinite or not why ? this is right the core of this probelm. if we consider only the spatial part of of the solution of geodesic equation, fine, but it's multiplied by S(t) which has no bounds because the time dimension in our universe has no bounds (no upper limit) so the whole distance (to something) relation has no bounds in spacetime interpretation, if I can say so. So here I recall the question why can't we say the spacetime is infinite, which reduces just to what's the maximal length of your X_st ? > > > > If you can think of an alternative model which only models our past > > > time cone, fine. > > btw. > > if the accurate model predict things in the past, I see no reason why > > it should not predict also things in the future. > > You can't predict things in the past. Astronomers doing models often talk about > "predicting" observations already made, but this is just astropolitics. > > The reality is that you can only postdict the past, and that if you make > predictions they will usually be wrong. Moreover, you're more likely to > get observing time/grants if you postdict the past (and say that you're > predicting it) rather than if you make real predictions. > > As for accuracy, the model below is extremely accurate, by definition. > > > below this this point I don't follow ;) > > Another way of describing the model is that the Universe the inside of a > 6k-light-year sphere and that initial (and continuing) boundary conditions > on the sphere have been designed in such a way that people trying to > understand them conclude with a series of simple (but wrong) physical > laws. Initial conditions throughout the sphere were also set up with > the same intention (e.g. fossils, distribution of continents, genetic > mixes of people and other animals, isotopic ratios of uranium etc...) > > Maybe another way of describing it is that we live inside a planetarium > of radius 6kly and that The Designer is pretty good at designing fun > models with just enough clues that we remain interested and think we > can understand the model represented in the planetarium. > > > > It's a model which perfectly fits all cosmological observations, > > > including those of WMAP. ;) The Universe in this model is the inside > > > > gash, does it says about CMB fluctuations ? > > No: but since human beings have interpreted these in terms of a simple > set of physical laws, the Christian fundamentalist model is satisfied > - there are simply a new set of boundary conditions designed to make > physicists interpret them this way. >

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Re: prosba o komentarz
by szajtan odwieczny 29 Oct '03

29 Oct '03

> > On Tue, 28 Oct 2003, szajtan odwieczny wrote: > > > What I think we can say for sure is that, although we're not sure about > > the actual curvature of our obserwable universe, and thus we're not sure > > if the space go on and on to infinity, it seems that it's quite sure that > > our universe is accelerating (q<0), and from this point of view we can say > > that if we send out a probe into the space even at the velocity of light, > > it's likely that it will never return regardelss of the the curvature > > of the universe, because it just won't overpass the expantion rate of the > > universe unless there is some nontrivial topology involved. The Big Crunch > > never happens in area where q<0 on Omega_l, Omega_m plane. So from our > > point of view we can say the spacetime is infinite if we're thinking in a > > We can't say "the spacetime is infinite". What you mean is why not ? event horizon accounts for all evolution of expantion according to assumed model. if it's less than the curent curvature radius then we won't see the probe, if it's bigger we mae but not must see it, for the curvature radius is changing in time. > "the http://www.wikipedia.org/wiki/Event_horizon is less than > 2 \pi times the radius of curvature even if comoving space is a hypersphere". last time I checked the page expired so don't know what was there, but did anyone said something about the relation of the event horizon to the curvature ratius.? (this should be calculated) > > This is true even when \Omega_\Lambda = 0 - the Big Crunch happens > before we can see the back of our head. > even better - another reason for which we will never see the sent signal (probe), but with CDM=.3 and DE=.7 or anything close to it we have no big crunch at all. > > way of traveling in it. If we think just of a space as a slice in some > > moment of time the quiestion is still open, but what is use of thinking > > i think you mean here "in some spatial section at constant cosmological time". yes > > about space this way - it just cannot be separated from time right ? > > It's the fundamental nature of the model, so we ought to think about it. the fundamental nature of the model is that going in space we also move in time. eg. Imagine that that space is closed, and expands slow enough that a photon emited from your flashlight can round it, but as the time passes expansion rate mae grow up, event horizon falls, (say cosmological constant starts dominate) and the photon won't make it eventually. > > If you can think of an alternative model which only models our past > time cone, fine. btw. if the accurate model predict things in the past, I see no reason why it should not predict also things in the future. below this this point I don't follow ;) > But personally this reminds me of the Christian > fundamentalist cosmology model where the Unvierse is only 6000 years > old, as written in the Bible. > > It's a model which perfectly fits all cosmological observations, > including those of WMAP. ;) The Universe in this model is the inside gash, does it says about CMB fluctuations ? meaybe I should review the bible instead of Peebles, etc :) > of a sphere of radius 6000 light-years, on which EM radiation of all > sorts of wavelengths (and we could add other particles) was generated > 6000 years ago on this surface, emitted in the direction of the Sun > (and it continues to be generated) in such a way to reproduce a > "naive" model that makes it (more or less) easy for human beings to > interpret these in terms of simple laws of physics. The being "God/Bóg" > which generates the emission wants human beings to have an easily > interpretable Universe, he/she/it is extremely intelligent and able > to generate such complex emission patterns of radiation. Just like > he/she/it set up species of animals 6000 years ago in a way that > makes biologists think there must have been lots of evolution... > > Personally i find the model ridiculous, but it perfectly fits all the > observations and avoids "extrapolation" into times with which we have > no written contact (prehistorical), and the Universe is only 6000 > years old. pozdrawiam bartek.

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Re: prosba o komentarz
by szajtan odwieczny 28 Oct '03

28 Oct '03

What I think we can say for sure is that, although we're not sure about the actual curvature of our obserwable universe, and thus we're not sure if the space go on and on to infinity, it seems that it's quite sure that our universe is accelerating (q<0), and from this point of view we can say that if we send out a probe into the space even at the velocity of light, it's likely that it will never return regardelss of the the curvature of the universe, because it just won't overpass the expantion rate of the universe unless there is some nontrivial topology involved. The Big Crunch never happens in area where q<0 on Omega_l, Omega_m plane. So from our point of view we can say the spacetime is infinite if we're thinking in a way of traveling in it. If we think just of a space as a slice in some moment of time the quiestion is still open, but what is use of thinking about space this way - it just cannot be separated from time right ? bart.

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multipole vectors - another hint for topology?
by Boud Roukema 21 Oct '03

21 Oct '03

http://de.arxiv.org/abs/astro-ph/0310511 ...We find that the result from comparing the oriented area of planes defined by these vectors between multipole pairs 2 <= l1 != l2 <= 8 is inconsistent with the isotropic Gaussian hypothesis at the 98.8% level for the ILC map and at 99.6% level for the cleaned map of Tegmark et al. A particular correlation is suggested between the l=3 and l=8 multipoles, as well as several other pairs. This effect is entirely different from the now familiar planarity and alignment of the quadrupole and octupole: while the aforementioned is fairly unlikely, the multipole vectors indicate correlations not expected in Gaussian random skies that make them unusually likely. ... If it's not topology, it's something else weird (politically incorrect ;) that happened on near-horizon scales... pozd boud

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by joseph mobutu 20 Oct '03

20 Oct '03

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Re: ksztalt Wszechswiata i media kontrolowane
by Andrzej Kus 16 Oct '03

16 Oct '03

Boud, Please ask someone from the group to correct polish in the > http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/OswiadczeniePraso… Some parts, as it is for the press, are not clear, perhaps Andrzej Marecki can do the job. This is very interesting and important development ! Cheers Andrzej K.

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prosba o komentarz (fwd)
by Boud Roukema 16 Oct '03

16 Oct '03

hi everyone, i definitely think we should respond to this - but i would prefer it to be a collective response - there's no reason why only my name should be cited - e.g., we could at least have the official "team" who was on the grant (amr + motyl + magda + bartek + sebastian + me), but if someone else wants to participate (i guess we can call this an official "press release" (oświadczenie prasowe)) that would be good, especially someone from CAMK to show that we work together despite the bureaucratic difference between CA-UMK and CAMK. As i understand it, Łukasz is in a hurry - he'll ring back at 15.00 - so i'll try to get a draft to the list within the next half hour or so. pozd boud > ---------- Forwarded message ---------- > Date: Tue, 14 Oct 2003 12:07:10 +0200 > From: Lukasz Kaniewski <l.kaniewski at rzeczpospolita.pl> > To: boud at astro.uni.torun.pl > Subject: prosba o komentarz > > Szanowny Panie doktorze! W zeszlym tygodniu w "Nature" ukazaly sie > wyniki badan dotyczacych ksztaltu i rozmiaru Wszechswiata. > > http://www.eurekalert.org/pub_releases/2003-10/ns-dtu100803.php > > Czy moglby Pan wyslac mi swaja opinie na temat tych wynikow? Prosze o > kilka lub kilkanascie zdan - mailem, bylbym wdzieczny za szybka > odpowiedz. > Sprobuje zadzwonic jeszcze do Pan okolo trzeciej. > Dziekuje - Lukasz Kaniewski, dziennik "Rzeczpospolita". >

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Re: prosba o komentarz
by Boud Roukema 16 Oct '03

16 Oct '03

Dear Łukasz, We have a draft version of a text here: http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/OswiadczeniePraso… but clearly the po polsku is not yet correct. It would probably be better that one of us corrects the po polsku in order to avoid introducing scientific errors, but it is unlikely that this will be ready by 18.00 today. If you can wait till later in the evening, then maybe we will have a better version ready for you. Alternatively, you could just click on "Register" on that page and make yourself your own username + password, then return to the page and click on Edit. Make the language corrections, click Preview and Save when you're happy. I (and maybe some of the others) will check later this evening to see if the scientific meaning is still correct after the corrections, but I'll be offline for the next few hours. Feel free to reply directly to our mailing list (cosmo-torun at astro.uni.torun.pl). *** Please keep the URLs (http links), at least you may shift them as references to the end of the article if you don't like them in the middle of the sentence - the aim of an article about cosmology in a major newspaper should not only be to "inform" readers, but also to give the power to readers to *inform themselves*. By including URLs - even in the paper version - some fraction (10-20%) of the readers will be able to explore further and will have some independence both from Rzeczpospolita editors/writers and from CA-UMK/CAMK scientists. Maybe only 1% will really do this, but the principle of giving maximum power to the reader is a fundamental part of intellectual freedom. pozdrawiam boud On Tue, 14 Oct 2003, Lukasz Kaniewski wrote: > Szanowny Panie doktorze! W zeszlym tygodniu w "Nature" ukazaly sie > wyniki badan dotyczacych ksztaltu i rozmiaru Wszechswiata. > > http://www.eurekalert.org/pub_releases/2003-10/ns-dtu100803.php > > Czy moglby Pan wyslac mi swaja opinie na temat tych wynikow? Prosze o > kilka lub kilkanascie zdan - mailem, bylbym wdzieczny za szybka > odpowiedz. > Sprobuje zadzwonic jeszcze do Pan okolo trzeciej. > Dziekuje - Lukasz Kaniewski, dziennik "Rzeczpospolita".

3 4

Dodecahedral space topology
by Andrzej Marecki 10 Oct '03

10 Oct '03

----- Forwarded message from NatureAlert ----- [...] Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background JEAN-PIERRE LUMINET, JEFFREY R. WEEKS, ALAIN RIAZUELO, ROLAND LEHOUCQ & JEAN-PHILIPPE UZAN http://info.nature.com/cgi-bin24/DM/y/eMJG0BfWLH0Ch0EeW0Ay [...] ----- End of forwarded message from NatureAlert ----- Nature's politics require embargo for articles before they are in the current issue on Nature so the authors couldn't post it on astro-ph but hope they'll do so. ;-) A.M.

2 2

No topological signal detected in WMAP data
by Andrzej Marecki 10 Oct '03

10 Oct '03

Paper: astro-ph/0310233 From: Neil J. Cornish <cornish(a)physics.montana.edu> Date: Wed, 8 Oct 2003 20:27:22 GMT (16kb) Title: Constraining the Topology of the Universe Authors: Neil J. Cornish, David N. Spergel, Glenn D. Starkman and Eiichiro Komatsu Comments: Submitted to PRL \\ The first year data from the Wilkinson Microwave Anisotropy Probe are used to place stringent constraints on the topology of the Universe. We search for pairs of circles on the sky with similar temperature patterns along each circle. We restrict the search to back-to-back circle pairs, and to nearly back-to-back circle pairs, as this covers the majority of the topologies that one might hope to detect in a nearly flat universe. We do not find any matched circles with radius greater than 25 degrees. For a wide class of models, the non-detection rules out the possibility that we live in a universe with topology scale smaller than 24 Gpc. ------------------------------------------------------------------------------

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double double-lobed FR IIs
by Boud Roukema 03 Oct '03

03 Oct '03

http://arxiv.org/abs/astro-ph/0310045 Double-double radio galaxies: remnants of merger of supermassive binary black holes Sounds like a model from what andrzej presented yesterday.

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EARA workshop at IAP (fwd)
by boud 30 Sep '03

30 Sep '03

> ---------- Forwarded message ---------- > Date: Mon, 29 Sep 2003 16:02:13 +0200 (CEST) > From: Caroline Terquem <terquem at iap.fr> > Subject: EARA workshop at IAP > > > Dear colleague, > > The IAP will host an EARA workshop entitled: > > The interplay between galaxy interactions, black holes, starbursts > and galaxy formation > > The dates (which we set from people's preferences and local constraints > with other meetings in Paris) are: > > December 4 and 5, 2003 (Thursday & Friday) > > You are invited to attend and present your work. > > Please let us know if you can attend as soon as possible, and send us a title. > > all the best > > Gary Mamon > Andrea Cattaneo > Bruno Guiderdoni > Avishai Dekel

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Re: A Big Rip instead of Big Crunch?
by Jaroslaw Rzepecki 30 Aug '03

30 Aug '03

>About 3 months before the end the solar >system would become undone. About 30 minutes before that the Earth >would explode. And about 10^-19 seconds before the ultimate >moment of doom, atoms would be pulled apart Hi! I never quite understood this... what do you mean by 3 months, 30 min, 10^-19s? Is this the time measured by my local clock? General question is: What would happen to time dimension in such a fast accelerating universe? Cheers Jarek

1 0

A Big Rip instead of Big Crunch?
by Andrzej Marecki 29 Aug '03

29 Aug '03

----- Forwarded message from physnews(a)aip.org ----- PHYSICS NEWS UPDATE The American Institute of Physics Bulletin of Physics News Number 651 August 28, 2003 by Phillip F. Schewe, Ben Stein, and James Riordon THE BIG RIP: A NEW COSMIC DOOMSDAY scenario takes the present acceleration of the expansion of the universe to new extremes. Dartmouth physicist Robert Caldwell and his colleagues Marc Kamionkowski and Nevin Weinberg at Caltech have determined that if the supposed dark energy responsible for the acceleration is potent enough not only will the space between galaxies continue to increase but that the galaxies themselves will fly apart as will, at successive times stars, planets, and even atoms and nuclei. Since the acceleration idea became established with astronomers a few years ago in the wake of observations of distant supernovae, it has been conventional to apportion the supposed energy inventory of the universe as follows: 5% in the form of conventional baryon matter (out of which atoms are made), 25% in the form of dark matter, and the biggest part, 70%, in the form of dark energy. Not a lot is known about dark matter, and even less about dark energy. Cosmologists have taken to discussing the enigmatic properties of the dark energy with the use of a new parameter, w, which is the ratio of its average pressure to energy density. The degree of this runaway expansion impulse is expressed by w. What is the nature of dark energy and how does it overcome the attractive pull of gravitation in order to speed up the cosmic expansion, and what is the proper value of w? In the best known model, the "cosmological constant" in Einstein's famous equations of general relativity corresponds to energy and pressure of the universal quantum vacuum, and is constant in space and time. Here the value of w is -1. In a second popular model, the "quintessence"model, the dark energy is associated with a universal quantum field relaxing towards some final state. Here the energy density and pressure of the dark energy are slowly decreasing with time, and the value of w is somewhere between -1/3 and -1 (w must be smaller than -1/3 in order for cosmic acceleration to occur). In Caldwell's "phantom energy" model, there is no stable vacuum quantum state and the energy density and the expansionary pressure exerted on the universe seems to increase even as the spacetime itself expands (with ordinary gases, pressure falls with expansion). In this scenario w is less than -1. The implications of this new type of cosmology are that bound systems should in the course of time be ripped up (see figure at http://www.aip.org/mgr/png/2003/200.htm ). For example, at a w value of -1.5 the universe would last for 35 billion years before being ripped apart. About 60 million years before the end, the Milky Way would be torn apart. About 3 months before the end the solar system would become undone. About 30 minutes before that the Earth would explode. And about 10^-19 seconds before the ultimate moment of doom, atoms would be pulled apart. Caldwell (robert.r.caldwell(a)dartmouth.edu, 603-646-2742) suggests that deciding between this model and the others might be possible in coming years with much better data coming from microwave background, supernovae, and galaxy measurements. (Caldwell et al., Physical Review Letters, 15 August 2003; text at www.aip.org/physnews/select) [...] ----- End of forwarded message from physnews(a)aip.org -----

2 1

open zwicky proposal - deadline Mon 7 July 2003
by boud 30 Jun '03

30 Jun '03

Hi everyone, I think people have had enough time to see how wiki pages work internally http://adjani.astro.uni.torun.pl:9673/zwicky/ and how they work externally where anybody at all with internet access can modify pages http://pl.wikipedia.org So I think it's time to have some open zwiki (or other wiki software) pages on adjani for organising things like: - cosmic topology research - cosmic standard ruler stuff - OCRA coordination - other research projects - cosmo/extragalactic session at http://www.pta.edu.pl/zjazd - other conferences where there's no point creating a new password for everyone who might want to make a comment or change something. So this is my proposal. Please provide comments, a modified, improved version of the proposal, or if you really think this goes against the purpose of why we are here - observational cosmology research - then you may *block* the proposal, but in that case you take responsibility for having blocked. (This is the style of consensus decision-making, for anyone who forgot...) pozdrawiam boud ********************************************************************** PROPOSAL for open (z)wiki pages. DECISION DEADLINE Mon 7 July 2003 It is proposed to have some wiki pages, separate from the present pages http://adjani.astro.uni.torun.pl:9673/zwicky/ For example, with a name http://adjani.astro.uni.torun.pl:9673/open/ to make it clear that it's an open zwiki. The purpose will be to organise things like - cosmic topology research - cosmic standard ruler stuff - OCRA coordination - other research projects - cosmo/extragalactic session at http://www.pta.edu.pl/zjazd - other conferences where cosmologists (faculty, postdocs, students) from outside of TCfA will be able to contribute to pages, update them, etc. Although hypothetically this means that web surfers might write rubbish on the pages, in practice there will hopefully be enough real cosmology users on the pages that any rubbish will quickly be removed by the real users. The example of http://pl.wikipedia.org shows that this is possible and practical, with good results. **********************************************************************

1 0

H0=75km/s/Mpc
by Andrzej Marecki 12 Jun '03

12 Jun '03

----- Forwarded message from send mail ONLY to astro-ph ----- [...] Paper: astro-ph/0306216 From: L.V.E. Koopmans <leon(a)astro.rug.nl> Date: Wed, 11 Jun 2003 01:59:39 GMT (350kb) Title: The Hubble Constant from the Gravitational Lens B1608+656 Authors: L.V.E. Koopmans (Caltech/STScI), T. Treu (Caltech), C.D. Fassnacht (UC Davis), R.D. Blandford (Caltech), G. Surpi (Caltech) Comments: 16 pages, 6 figures, 5 tables; submitted to ApJ \\ We present a refined gravitational lens model of the four-image lens system B1608+656 based on new and improved observational constraints: [...] A combined gravitational-lens and stellar dynamical analysis leads to a value of the Hubble Constant of H_0=75(+7/-6) km/s/Mpc (68 percent CL; Omega_m=0.3, Omega_Lambda=0.7. [...] ----- End of forwarded message from send mail ONLY to astro-ph ----- It's important to note that originally the same group claimed that H0 might be as low as... 61 km/s/Mpc, see: Fassnacht et al. (2002) ApJ, 581, 823 -- Andrzej

1 0

unofficial unofficial grant results :(
by Boud Roukema 10 Jun '03

10 Jun '03

Hi everyone (on the grant proposal), The unofficial unofficial grants results are negative, sorry. :( The official unofficial results should be found as Konkurs XXV here within a few days: http://www.astrouw.edu.pl/~kst/konkursy.html And the official official results probably within 3-4 weeks. i'll be in Blois next week: http://blois.in2p3.fr/2003/pages/inform2.html but in July and August i'll be more or less in Toruń/Piwnice, though probably working from home more often than from my office. i'm not eager to do the paperwork again, but i guess the funding arithmetic can be the same, we only need to change the scientific plan and translate it to po polsku. IMHO, it's probably not worth trying again in topology, i think we should consider a plan which is more or less: ArFus - galaxy formation modelling + SMBH merger models for inducing AGN formation => RLAGN birth, youth and death observational (phenomenological) population constraints Nothing will stop us doing topology anyway, and this sort of work is something i think we should do anyway - it's the obvious way of combining our best observational and theoretical experience on a subject where it is certain that the objects of interest exist! The difficult question is how Bartek can fit into this. Bartek: any ideas? How about something like the reionisation epoch, around z=10-20? Since WMAP, people are coming up with all sorts of stuff on this. Hmmm... How about predictions for SKA? http://www.skatelescope.org/ That should find star-forming galaxies at redshifts anywhere around z=5-20, and SMBH and AGN formation around then should certainly be affected by when and how reionisation happened, making the link with RLAGN evolution modelling. Anyway, please say what you think, is it realistic to do this during July - including Polish translation etc etc - when everyone would rather be doing theoretical cosmology in the warm sunshine outside? pozd boud

1 0

PTA wrzesnia - can we have a cosmo session?
by boud 10 Jun '03

10 Jun '03

Cześć, Would it be possible for the cosmologists in Poland to organise a session during the PTA in September? Since many of us may be attending anyway, we might as well do this in an organised and open way rather than just as a random meeting among friends who already know each other... My idea would be to use the mailing list cosmo-pl(a)astro.uni.torun.pl so that everybody from Toruń, Warszawa, Kraków and other cosmologists with Polish connections can coordinate, decide on a programme, etc. I would be happy to facilitate (moderować) the discussions. I guess the questions to the LKO would be: (1) How much time can we have in total? half-a-day? a few hours? (2) Would a meeting in the full session be best, or would a parallel session be better? But they would have to evolve depending on how much interest there is to Polish cosmologists. For the moment I'm only cc-ing this to cosmo-torun, so that we have some "local" coordination first, before PL level coordination. I'm not yet a member of the PTA, but of course I would be happy to become a member. pozdrawiam Boud PS: Is there an http: reference to the meeting details?

2 1

SZ - OCRA paper - Battye Weller
by Boud Roukema 30 May '03

30 May '03

http://de.arxiv.org/abs/astro-ph/0305568

1 0

Dark matter - yes, MOND - no.
by Andrzej Marecki 23 May '03

23 May '03

----- Forwarded message from physnews(a)aip.org ----- THE CONVENTIONAL THEORY OF DARK MATTER just got some potent support from a new batch of observations to be reported by scientists from the Sloan Digital Sky Survey (SDSS) this week at a meeting in the Canary Islands. One of the main reasons for believing in the existence of non-luminous matter is that the motions of galaxies within galaxy clusters and the motions of matter around individual galaxies seems to defy conventional celestial mechanics. Either plenty of extra (but unconventional) mass must lurk in the vicinity of the galaxies (the dark matter theory) or the known laws of physics might be in need of amendment (the theory known as modified Newtonian dynamics, or MOND). Scrutinizing a subset of 3000 galaxies (from Sloan's inventory of 250,000 galaxies) with satellite galaxies in tow, the researchers' profile of satellite velocities supported the dark matter theory and discounted the MOND idea. (See the Sloan website at www.sdss.org ) ----- End of forwarded message from physnews(a)aip.org ----- -- Andrzej

1 0

Weyssenhoff fluid article - Szydlowski & Krawiec
by Boud Roukema 21 May '03

21 May '03

Cześć Adam (z Krakowie), Zobaczyłem twoj artykuł z Marekem Szydłowskiego: http://de.arxiv.org/abs/astro-ph/0305364 Chyba już znasz, ale w Toruniu próbujemy rozwijać komunikacji między kosmologów i ekstragalaktyków w Polsce - możesz napisać się na lista mejla cosmo-pl małpa astro.uni.torun.pl tutaj: http://www.astro.uni.torun.pl/sympa/cosmo-pl/index.html SUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "subscribe cosmo-pl" W tej chwili nie są wiele mejlów (ryzyko spam jest bardzo niski, oprócz spam od mnie :), ale kiedy ktoś chce używać ta lista, może być użyteczny. Mniej-więcej są osób z Toruniu + Wwie + Krakowie + kilka na granicą (Bohdan P, Radek Stompor, Krz Górski). Najaktywne listy mejla u nas chyba są http://www.astro.uni.torun.pl/sympa/cosmo-torun/index.html http://www.astro.uni.torun.pl/sympa/shape-univ/index.html i stron Zwicky: http://adjani.astro.uni.torun.pl:9673/zwicky/TCfACosmology Chyba teraz najłatwiejszy okazja dla spotka kosmo w Polsce będzie spotka PTA w Toruniu, widocznie: 8-10.09.2003 http://www.phys.uni.torun.pl/phys/KONFERENCJE/konf-w2003.html ale wiem że potrzebuję iść do Krakowie dla spotykać z wasz... pozdrawiam boud

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