From boud w astro.uni.torun.pl Fri Feb 1 18:09:02 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Fri, 1 Feb 2002 18:09:02 +0100 (CET) Subject: (1) proceedings (2) new lists (3) www link (4) Moriond Message-ID: Cze�� wszystkie, (1) proceedings ;) (2) A.M.: new lists please! (3) vario w ...? link from home page to .../sympa/ (4) someone to go to Moriond? ---------------------------------------------------------------------- (1) The good news about proceedings for the Wed 23 Jan mini-workshop is that... you don't have to write them! But seriously, it's probably useful for those outside of Toru� to have a brief idea of what went on, so here's my version of proceedings - any one else is free to correct them! My memory and judgment are not perfect. (In fact, proof that I am capable of making errors in judgment comes from the fact that I thought people would only be comfortable with a one hour meeting - look through the archive and you'll see this. Andrzej M. suggested a full afternoon, and I thought he was wrong. Thanks to this list, his idea was adopted, and he was right and I was wrong - thanks Andrzej!) The mini-workshop went well, IMHO. Starting from the general relativity basics of what scalar fields and quintessence are (Micha� F), going through Toru�'s big observational project which could in principle lead to direct measurement of local cosmological parameters like curvature, but maybe also quintessence and the details of perturbation statistics (Sebastian) and then an introduction to curvature and topology (Rafa�), we got back to the galaxy scale with Micha� H on how magnetic fields evolve within galaxies and how this should be related to star formation, with a nice flow diagram showing all the links and some nice videos of simulations, and then observational work on topology (Andrzej M) and on the curvature parameters (me). A lot to absorb in one afternoon. We even had several non-speaking participants! So, hopefully this will start everyone thinking about what each other is interested in and how we can have useful, productive conversations with each other. Since time ran short, we only had a brief discussion on organising questions, a main result which was people just suggested I create additional mailing lists and so how their usage evolves. Hence, point (2)... ---------------------------------------------------------------------- (2) Andrzej M, could you please create the following three mailing lists on sympa, just copy all the initial properties of cosmo-torun (except for the htaccess file, these three should be with open access, so no htaccess file is needed), and I'll adjust things once you've made them and got the daemons running. Here I'll just put the names I suggest and the descriptions. (2a) name: cosmo-spotka description: This mailing list is for all sorts of discussions on meetings of various sorts related to cosmology at Toru�. This can include (1) Discussion of what sort and frequency of regular TCfA meetings to organise (weekly vs fortnightly vs monthly; presentations of own research vs "journal club" talks on cosmo news items vs creative new idea generation sessions vs introductory reviews; should we have a separate seminar from the regular Monday ones or just use the Monday ones? - probably all these questions should be left open and fluid for some time and will probably be answered in an evolving way - hence the need for a list!); (2) Other organising info on TCfA meetings themselves; (3) Offers by people, e.g. from around Poland or internationally, to give cosmo seminars - if someone wants to give a seminar, they should briefly introduce themselves here and say something like "hey, I'd like to give a talk at Toru�", this way the information flow will be more efficient than if it has to go through just one seminar organiser; (4) Requests by outsiders for a Toru� person to give a seminar at their institute can go directly to this list - this would help give everyone a chance at giving outside seminars. (5) Other meeting related discussion. (2b) name: cosmo-pl description: Debaty generalne mi�dzy kosmologi w polsce, dla organisowa� badania i spotkanie kosmologi. Mo�e by� kilka rozmawiane b�d� zacz�� tutaj i przeprowdza� si� do cosmo-spotka, lub vice-versa. Nie jest problemu. R�nica: cel cosmo-spotka jest TCfA, a cel ta lista jest ca�a grupy lub naukowcy individualny z kosmologiem w Polsce. Chyba b�d� uzywa� po polsku, je�li po polsku kosmology zagraniczn�w nie jest zbytnio �mieszny ;). Wol� kodeks litery latin-2 (iso-8859-2), nie kodeks Micro$oft. [You can correct the po polsku putting in the correct odmian przypadk�w, if you like, o.w. just put it as it is!] (2c) name: cos-rule description: This list is for organising a workshop on the claimed features in the power spectrum/correlation function of extragalactic objects on scales at or above 100h^-1Mpc. According to standard "linear theory" of the FLRW model, these features should serve as cosmological standard rulers if they real, and initial results certainly favour this. Both observational results, for and against, and theoretical explanations, are sought for this workshop. It would be hoped to organise this for the Northern Spring/Summer of 2002, at Toru�. Anyone wishing to speak or help organise is welcome to post an introductory message here and participate. ---------------------------------------------------------------------- (3) I propose that on the left bar of the www.astro. ... page we have a yellow tage with something like "Cosmology group" pointing to .../sympa/ so that people can easily find all four lists. If people agree, could someone do this? (Apparently vario w ... is the webmaster.) ---------------------------------------------------------------------- (4) Moriond - The Cosmological Model Les Arcs, France (March 16-23, 2002) http://moriond.in2p3.fr/J02/ I noticed there's special funding for East Europeans to go to this, and I don't know of many EE cosmo groups who could take up the offer... Polish people under 35 can also get funding under the "European" heading (see the page). This would be a good meeting for learning standard stuff (e.g. for starting to think about what to do with OCRA...), and for starting to get to know other European cosmologists, but it's *very* expensive and no point going unless you're fully funded. (You had also better like skiing - talks are something like 9:00-12:30 and 4:30-7:30, so that most people ski in the afternoon... ) Officially the funding deadlines have passed, but if very few East Europeans have applied, the organisers might be happy to accept some late offers. Be warned that any travel requires a bit of time invested, paperwork etc., thinking about the budget, but I think most of us have some travel experience. It's also a distraction from getting work done. But might give you new ideas or help you learn things. If anyone wants to apply, it might help if you do a cc: to me which would show to the organisers that you're in contact with someone they know, but I'm in Paris for getting a visa right now so I can't sign any forms for you - and in any case, you need a "senior scientist" to sign the request for funding form. ---------------------------------------------------------------------- Pozdrawiam Boud From boud w astro.uni.torun.pl Thu Feb 14 19:55:39 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Thu, 14 Feb 2002 19:55:39 +0100 (CET) Subject: favoured topology of Universe candidates In-Reply-To: <16.1a391306.299d505f@aol.com> Message-ID: Hi again Ken & Ali, On Thu, 14 Feb 2002 Kengrimes123 w aol.com wrote: > Thanks for that. We were rather shamefully going for the following 'quick > fix.' What do you think: The problem is that a spherical or hyperbolic, small universe would be just as exciting as a flat, small universe. The former might be more difficult to imagine, and there's more chance that Cornish et al would make errors or miss the real signal or take longer to find the result for a spherical or hyperbolic small universe than for a small, flat universe, but to me that's a secondary issue. (Using the circles principle in the most general way, the infinities of possibilities are not a problem for detection, however paradoxical that might seem!) Nevertheless, if what you really want to say is that a flat, small universe is in some ways "nicer" or "simpler" than a spherical or hyperbolic, small universe, then that is valid (and certainly defendable), but should probably be worded a bit more carefully. It would not really be that much more "hidden" from the measurement point of view, it would be more hidden simply because it's more complicated. I think the following is correct, clear and probably close to what you want to say: Replace: > 'So the universe may indeed be finite and bounded, and yet too vast to yield > to us the secret of its shape. Alternatively, the universe may possess > spherical or hyperbolic curvature, and so hide its secret shape among > limitless possibilities. Such thoughts are met with quiet stoicism by the > new wave of cosmologists: "The universe is however it is," Roukema > acknowledges, "Not how I would like it to be." by % 'So the universe may indeed be finite, bounded and flat, % and yet too vast to yield % to us the secret of its shape. Alternatively, the universe may be % small but possess % spherical or hyperbolic curvature, and so hide its secret shape among % limitless possibilities difficult for ordinary mortals to imagine % and challenging for professional % cosmologists to extract from the MAP data. Such thoughts ... And then the 2nd paragraph is fine unchanged: > But there remains the tantalising third possibility - that the universe is > relatively small, and possesses flat curvature. In that case, within a few > months of reading this article, we might well know whether Homer's donut is > truly the shape of things to come.' Cheers Boud From boud w astro.uni.torun.pl Tue Feb 19 22:10:14 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Tue, 19 Feb 2002 22:10:14 +0100 (MET) Subject: cosmo TCfA mailing lists - Witamy! Message-ID: Dear Anna, Magdalena, Nazywam si� Boud Roukema. I am about to start a job at TCfA to help organise a cosmology/extragalactic research group. Sebastian just told me that you are TCfA PhD students spending some time in JBO. To help organise discussion about research projects and techniques among us, Andrzej Marecki and I have started to create some email discussion lists, which are archived on the web. If you look at the pages: http://www.astro.uni.torun.pl/sympa/ you'll see that there are several lists which might interest you. Since you are at JBO on a long time scale, probably the cosmo-torun list would be the one most useful for you right now - but, of course, you're free to subscribe to any of the lists. The list cosmo-pl would probably interest you too - for the moment there are no messages - it will evolve depending on how people want it to evolve! (I m�j po polsku nie jeszcze jest wystarczy dobry dla dobrze dyskutowa� w tej listy mejla...) So I've subscribed you both to cosmo-torun and cosmo-pl (using your astro.torun addresses - you can still send mail to the lists from a JBO address, but it requires an authentification key to avoid spam). Of course you may unsubscribe if you think there are too many uninteresting messages... A very useful function is the archive - but since research ideas may be discussed *before* they are published, there is (moderately) limited access to the http://www.astro.uni.torun.pl/sympa/cosmo-torun/ archive. If you two and Motylek could tell me or Andrzej M (on-list or off-list) the IP numbers of computer(s) at JBO you are likely to use to access the site, then we would open up access to these IP #s. (The other existing lists have unrestricted access.) Pozdrawiam Boud From michalf w ncac.torun.pl Sat Feb 2 12:50:26 2002 From: michalf w ncac.torun.pl (Michal Frackowiak) Date: Sat, 2 Feb 2002 12:50:26 +0100 (CET) Subject: (1) proceedings (2) new lists (3) www link (4) Moriond In-Reply-To: Message-ID: > (4) Moriond - The Cosmological Model > Les Arcs, France (March 16-23, 2002) > > http://moriond.in2p3.fr/J02/ > > I noticed there's special funding for East Europeans to go to this, > and I don't know of many EE cosmo groups who could take up the offer... > Polish people under 35 can also get funding under the "European" heading > (see the page). I dont know what infulence on the organizers you have, but all the deadlines are crossed already, for registration and financial support. I have registered and waiting for the decision about financing, which I believe should come next week. But the meeting looks good anyway! There will be some people from Warsaw CAMK as well. Michal From boud w astro.uni.torun.pl Sat Feb 2 14:06:47 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Sat, 2 Feb 2002 14:06:47 +0100 (CET) Subject: (1) proceedings (2) new lists (3) www link (4) Moriond In-Reply-To: Message-ID: On Sat, 2 Feb 2002, Michal Frackowiak wrote: > > (4) Moriond - The Cosmological Model > > Les Arcs, France (March 16-23, 2002) > I dont know what infulence on the organizers you have, but all the I don't either ;) . > deadlines are crossed already, for registration and financial support. I > have registered and waiting for the decision about financing, which I > believe should come next week. But the meeting looks good anyway! There > will be some people from Warsaw CAMK as well. OK, good, you can get to know them there - if you all get financed. Good luck! boud From amr w astro.uni.torun.pl Tue Feb 5 13:16:36 2002 From: amr w astro.uni.torun.pl (Andrzej Marecki) Date: Tue, 5 Feb 2002 13:16:36 +0100 (MET) Subject: (1) proceedings (2) new lists (3) www link (4) Moriond In-Reply-To: from Boud Roukema at "Feb 1, 2002 06:09:02 pm" Message-ID: <200202051216.NAA04060@galileo.astro.uni.torun.pl> > (2) Andrzej M, could you please create the following three mailing > lists on sympa, just copy all the initial properties of cosmo-torun Done. (Sorry for being late.) > (except for the htaccess file, these three should be with open access, > so no htaccess file is needed), and I'll adjust things once you've > made them and got the daemons running. The .htaccess file is actually in /home/sympa/arc not in a particular list catalogue. Don't know whether I can move it elsewhere.... The daemons have been restarted. > ---------------------------------------------------------------------- > (3) I propose that on the left bar of the www.astro. ... page we have > a yellow tage with something like "Cosmology group" pointing to > > .../sympa/ > > so that people can easily find all four lists. If people agree, could > someone do this? (Apparently vario w ... is the webmaster.) Vario will do this. -- Andrzej From boud w astro.uni.torun.pl Mon Feb 11 15:14:16 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Mon, 11 Feb 2002 15:14:16 +0100 (CET) Subject: =?iso-8859-1?Q?succ=E8s_du_vol_Archeops?= (fwd) Message-ID: > ---------- Forwarded message ---------- > Date: Fri, 08 Feb 2002 21:28:24 +0100 (MET) > From: Programme National de Cosmologie > To: diffusion PNC > Subject: [iso-8859-1] succ�s du vol Archeops > > --------------------------------------------------------------------------- > PNC PNC PNC http://webast.ast.obs-mip.fr/pnc/ PNC PNC PNC PNC > --------------------------------------------------------------------------- > message # 138 8 f�vrier 2002 > > 1. Succ�s du vol Archeops des 7 et 8 f�vrier 2002 > > --------------------------------------------------------------------------- > PNC PNC PNC http://webast.ast.obs-mip.fr/pnc/ PNC PNC PNC PNC > --------------------------------------------------------------------------- > > 1. Succ�s du vol Archeops des 7 et 8 f�vrier 2002 > > Apr�s un vol interrompu pr�maturement en janvier 2002 pour un > probl�me li� au ballon, la nacelle Archeops a effectu� un vol sans > faute de Kiruna (Su�de) jusqu'� Noril'sk (Sib�rie) de 19 heures au > plafond (dont 12h30 de nuit), conduit sous la responsabilit� du > CNES. Une analyse pr�liminaire des signaux montre une bonne > sensibilit� pour la mesure des anisotropies du rayonnement fossile > cosmologique a 3K. > > Cette r�ussite de l'un des programmes phare du PNC est un succ�s pour > toute notre communaut�. > > Toutes les informations sur Archeops et sur ce vol se trouvent sur > la page WEB de la collaboration : > http://www.archeops.org > This is good news for European observational cosmology - Archeops is a balloon project, mainly French, which will cover about 25% of the sky with more or less the same instruments to be used with Planck - but the observations are to be made much, much sooner... Brief translation: a flight of Archeops on 7/8 Feb 2002 went perfectly, from Kiruna (Sweden) to Noril'sk (Siberia) with 19 hours at the "roof" (12.5 h of night), organised by the CNES (French space agency). Initial analyses look good for 3K CMB fluctuation measurements. More info at the web site. Czesc Boud From boud w astro.uni.torun.pl Mon Feb 11 18:57:04 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Mon, 11 Feb 2002 18:57:04 +0100 (CET) Subject: favoured topology of Universe candidates In-Reply-To: <28.21ecf3a0.2996b155@aol.com> Message-ID: On Sat, 9 Feb 2002 Kengrimes123 w aol.com wrote: > Could you please confirm your title and institution for the Astronomy > article? Dear Ken & Alison, Title: Dr Institution (full name): Torun Centre for Astronomy, Nicholas Copernicus University International linguistic trivium: The "n" in Torun should have a "grave accent" on top, i.e. a forward slanting accent, like the accent on top of "e" in "�t�" ('et'e, = "summer" in French). > Date: Fri, 25 Jan 2002 16:51:33 EST > From: Kengrimes123 w aol.com > To: boud w astro.uni.torun.pl > Subject: Re: favoured topology of Universe candidates > > Sorry for the hiatus. We thought, 'We'll get back to Boud as soon as we've > got our heads round this.' Still trying! Did you get anywhere with this? I admit that in my case it took many years between learning about the existence of non-Euclidean geometry and developing an intuition in which I was satisfied that this was possible without needing an extra dimension. (The latter time happened to be when I attended a course on algebraic topology.) During the intervening time, I accepted that people were probably correct in their claims, but it was rather unsatisfying. My hope is that with proper explanation, the period of years could be replaced by the space of an hour or so..., or, at least, an hour or so of initial reading followed by a week of deep thought and playing with idea in one's mind... I'm sure that playing with the games on Jeff Weeks' site that I referred you to should help. Don't be embarrassed to play games - understanding is not a matter just of cold logic, it also requires intuition via the chaotic process of a neural network. Playing games is what mathematicians do most of the time. Since you're both journalists, probably the word games that Jeff has provided would sink deepest into the cores of your minds. E.g. try the games http://humber.northnet.org/weeks/TorusGames/html/WordSearch.html http://humber.northnet.org/weeks/TorusGames/html/Crossword.html with Java and auto-image-load enabled (this is probably the case by default). And try them with the "Klein bottle" setting! Try to "unlearn" what you thought you knew about physics, just have fun playing the games instead. Imagine you're really living in the WordSearch.html, like a good movie. And then, chances are a moment will occur when, all of a sudden, you'll realise that a multiply connected flat space makes perfect sense without needing an extra dimension... > Thanks, Ken & Alison. BTW, would you be able to run the final version of the draft text by me, at least the part of the text regarding our discussions? You would of course be free to ignore or follow my comments as you wish, but it would be good that I have the chance to at least make my suggestions. Cheers Boud From boud w astro.uni.torun.pl Thu Feb 14 16:24:23 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Thu, 14 Feb 2002 16:24:23 +0100 (CET) Subject: favoured topology of Universe candidates In-Reply-To: <127.c050913.299c54f1@aol.com> Message-ID: Hi Ken & Ali, On Wed, 13 Feb 2002 Kengrimes123 w aol.com wrote: > Please find attached as requested our latest draft of the article, which we > will be forwarding to our editor this Friday. Great! > We fear you may be somewhat disappointed with the finished product, since, as > you can see, we have not managed to cover the 'psychological crutch' aspect > of the 4th dimension. Although we found this discussion most interesting, we > simply found it impossible to fit into a popular account with a strict word > limit which had to cover so much other material. Our apologies. On the contrary, my general opinion of your article is that you've done a good job of making a simple as possible introduction to the subject and of covering the variety of research done in Europe/North America, given a non-expert background and a finite ;-) amount of time to learn the subject. (Including the several Brazilians and one Japanese researcher would have been fair, but would have required more time and reading and would have been difficult within the word limit.) I think there are several small changes that can be made in order to be correct about the "psychological crutch" aspect, which I've listed below as (1). These would only add a dozen or so words. Since I'm convinced that you've made an effort to try to understand the question - but probably without (yet) succeeding (it might happen sometime when you're in the shower or on summer holidays and daydreaming or whatever - and you'll suddenly say, of course!), I certainly won't hold it against you if you prefer not to make these changes. After all, only you two are signing it, not me! But I think it would be both in readers' and researchers' interests if if you did consider my suggested changes... There are also a few other corrections I've suggested. > We would, of course, still be most interested in any comments you might like > to offer (especially if we've made any howlers!) In the meantime, we would > like to take the opportunity to thank you for the time, interest and support > you have given us on this project. The most fun part of science is understanding the Universe, and helping others to understand the same things. Your help in transmitting this to others is definitely worth it. It's been a pleasure to work together. :-) All the best Boud ---------------------------------------------------------------------- (1) The "psychological crutch" aspect of the 4th dimension. (2) What are "photons"? (3) topological images of galaxies, not stars (4) Recent constraints show Universe flat like continents are flat (5) Infinitely many spherical spaces ---------------------------------------------------------------------- > This hard-to-visualise fourth dimension is particularly intriguing to > cosmologists because, if it exists, then the universe might be curved > within it. An immediate critique of this idea is that, to the best of (1) I would put: ... % cosmologists because it could be used to help imagine how the universe % might be closed. An immediate critique of this idea is that, % to the best of ---------------------------------------------------------------------- > joined to each other simultaneously [EXAMPLE AT ABOVE URL, PAGE 2]. If > this `cube' were the entire space of our three-dimensional universe, > then the bending operation, possible only in a fourth dimension, would (1) I would put: ... % then the bending operation, which can be imagined by using % a fourth dimension, would ---------------------------------------------------------------------- > began. The same would be true for our closed, curved, > higher-dimensional universe. Like an Asteroids-type starship, any (1) I would put: % began. The same would be true for our closed % universe. Like an Asteroids-type starship, any or % began. The same would be true for our closed % universe thought of inside a higher-dimensional artificial universe. Like an % Asteroids-type starship, any ---------------------------------------------------------------------- > The term any object includes, of course, photons. (2) I think that there are probably 10-100 times more people who have some notion of both "light" and "particles" but haven't the foggiest about "photons", so why not help enlighten them: % The term any object includes, of course, photons (particles of light). ---------------------------------------------------------------------- > In a closed, curved universe, (1) I would put: % In a closed universe (which could sort of be thought of as curved) ---------------------------------------------------------------------- > light itself would describe a curved path, eventually (1) I would put: % light itself could sort of be thought of describing a curved path, % eventually ---------------------------------------------------------------------- > The implications for contemporary cosmology are truly staggering. When > we look up at the night sky, it is possible that what we are seeing is > not a single, vast or infinite number of stars, but the same finite > set of stars repeated throughout the sky, like torchlights in a hall (3) You probably know that you're making an error here, with the goal of simplicity. We are certain that the size of the Universe is much bigger than our Galaxy - none of the stars we see with the naked eye are repeated, topological images of one another. (Unfortunately!) What solutions are possible to try to be correct without sacrificing understandability to the ordinary reader? Replacing "stars" by "astrophysical objects" would be correct but sound heavy and academic. In French you could use the word "astre" which is short and snappy and means an arbitrary object in the sky. But you're not writing in French. ;-) How about: % The implications for contemporary cosmology are truly staggering. When % we look up at distant galaxies in the night sky, % it is possible that what we are seeing is % not a single, vast or infinite number of galaxies, but the same finite % set of galaxies repeated throughout the sky, like torchlights in a hall ---------------------------------------------------------------------- > observations suggest that the universe is flat. (4) More accurate would be: % observations suggest that the universe is pretty close to flat, like % any continent on the Earth is pretty close to flat. ---------------------------------------------------------------------- > The number of contenders for shapes which could tile a flat or > spherical universe is limited, but a hyperbolic universe offers (5) A "howler", at least from the mathematical point of view! ;-) The number of shapes (in 3D) for both the spherical and hyperbolic cases is infinite [in mathematical jargon, these are both countable infinities, i.e. the same type of infinity as that of the ordinary counting numbers: 1,2,3,4,5, ...]. I made the *error* (published, I think) of repeating the claim by someone else (who I won't name) who said that the number of hyperbolic spaces is a bigger sort of infinity than the infinity of the spherical spaces. From Jeff Weeks' explanation, I accepted that this is wrong. It is true (as far as I understand) that the hyperbolic spaces are not yet completely classified by mathematicians, and their families are certainly more complicated in certain ways, while the spherical spaces are completely classified and form relatively simple families. But both numbers of spaces are infinite. I suggest: % The number of contenders for shapes which could tile a flat % universe is limited, but a spherical or hyperbolic universe would offer ---------------------------------------------------------------------- From boud w astro.uni.torun.pl Thu Feb 14 16:33:44 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Thu, 14 Feb 2002 16:33:44 +0100 (CET) Subject: MAP time scale, courtesy Ken & Ali Message-ID: Dear friends, For copyright reasons I probably shouldn't post Ken & Ali's full article here, but here are a couple of paragraphs which are pretty important: > But how can we spot these circles? From 1989-93, NASA's Cosmic > Background Explorer (COBE) mapped the microwave sky, and found that > it's not a perfect 3 Kelvin everywhere - there are slight fluctuations > in its temperature. Cornish, along with his collaborators David > Spergel of Princeton University and Glenn Starkman of Case Western > Reserve University in Cleveland, Ohio, thinks that searching for > patterns in these fluctuations may be the key to finding out the > universe's shape. > > The team hopes to trace out different temperature patterns along > circles, and then find the same pattern along another circle elsewhere > in the sky. Patterns of temperature around one circle should be > identical to another, says Cornish. The precise pattern of circles > will indicate the fundamental polyhedron's shape. > > COBE's achievement in making the first map of the microwave sky was > impressive. But the map wasn't quite detailed enough for > pattern-spotting. NASA's Microwave Anisotropy Probe (MAP), launched > last year, will map the microwave sky in unprecedented detail, > providing the data that Cornish, Spergel and Starkman need for their !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! > search. MAP will complete its first complete scan in March and then we > can begin our analysis, says Spergel. We hope to have the results by > the end of the year. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Of course, it's quite possible that they'll make too many simplifying assumptions or that the integrated Sachs-Wolfe effect (between us and the last scattering surface) or "foregrounds" will cause too much confusion and lead to a false exclusion (more likely than a false detection), so Planck might still have a chance. But Archeops data would clearly be the best competitor for MAP: 25% of the sky is not that far off from 67% of the sky... Cze�� Boud From boud w astro.uni.torun.pl Thu Feb 14 18:23:11 2002 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Thu, 14 Feb 2002 18:23:11 +0100 (CET) Subject: favoured topology of Universe candidates In-Reply-To: <18b.3557073.299d3c46@aol.com> Message-ID: Hi again Ken & Ali, On Thu, 14 Feb 2002 Kengrimes123 w aol.com wrote: > Thanks once again for the prompt feedback, which we would like to say was a > model in how to suggest quick and concrete improvements (if only more > contributors could do that!) We have gone for the simple expedient of > incorporating all of them. Great! Well, I've stoically ;-) learnt that careful, precise criticism tends to yield better results than general rants! > Please find below our proposed ending (featuring once more your good self - > and if you don't like the phrase 'quiet stoicism' we can go for 'cheerful > resignation' instead). We'd be very grateful if you could check this quickly, > as I think it probably repeats the 'howler' you picked out in your Point 5: > ' ... "If the universe is relatively large compared to its age,' > Levin observes, "I.e if it is significantly bigger than about 15 > billion light years across, then light from our ghost images will > not have time to reach us before the death of this planet." OK. > So the universe may indeed be finite and bounded, and yet too vast to yield > to us the secret of its shape. OK. > Alternatively, the universe may possess > hyperbolic curvature, and so hide its secret shape among limitless > possibilities. Hmm. Even though there are limitless possibilities for both the spherical and hyperbolic cases, as far as analysis of MAP data is concerned, the difference between them and the flat cases is "just" a question of calculation techniques and computer speeds. ("just" means a lot of hard work...) As you said in your article, Cornish et al. will calculate the easier cases first, simply because they're easier. The "limitless" or difficult classification of hyperbolic spaces just means it's much harder to analyse the data - the matched circles principle of Cornish, Spergel & Starkman is still perfectly valid. Just a reminder: the smallest "size" of the Universe could be: i) smaller than the horizon size (distance to last scattering surface) ii) about the same as the horizon (still maybe detectable) iii) much bigger than the horizon iv) infinite (There are in fact several "sizes" of the Universe which could be defined, the smallest one is the smallest distance between two images of the same object.) the curvature of the Universe can be: a) "slightly" spherical (like the Earth is "slightly" spherical) b) flat c) "slightly" hyperbolic There *is* some link between the two, [ a) => maximum size of Universe; b) => minimum size of Universe] but I think it's too subtle to include in your article, certainly too subtle for a conclusion. I think probably the closest correct thing to what you want to say is to compare the three possibilities: i) + ii) (put together) iii) iv) ---------------------------------------------------------------------- So here's my suggestion, to replace: > Alternatively, the universe may possess > hyperbolic curvature, and so hide its secret shape among limitless > possibilities. by % Alternatively, the universe may really be infinite and unbounded, % leaving us without the merest hope of being able to distinguish % between the two cases. ---------------------------------------------------------------------- > Such thoughts are met with quiet stoicism by the new wave of > cosmologists: "The universe is however it is," Roukema acknowledges, > "Not how I would like it to be." "quiet stoicism" and your quote are fine. :-) ---------------------------------------------------------------------- > But there remains the tantalising third possibility - that the universe is > neither vast nor hyperbolic. In that case, within a few months of reading To match the above correction: % neither vast nor infinite. In that case, within a few months of reading ---------------------------------------------------------------------- > this article, we might well know whether Homer's donut is truly the shape of > things to come.' Cheers Boud