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Gazeta Wyborcza o odkryciu Tegmarka
by Andrzej Marecki 18 Mar '03

18 Mar '03

Artykuł o odkryciu ("odkryciu" ?) Tegmarka: http://www.gazeta.pl/nauka/1,34148,1376101.html Krytyka Marka Demiańskiego: http://www.gazeta.pl/nauka/1,34148,1376526.html -- Andrzej

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Re: map data
by szajtan odwieczny 18 Mar '03

18 Mar '03

I know this looks bad ;) and ... discouraging. But non of is comes from my code. I just ploted the data from internet - from lambda. They get a nice spectra because they bin it every 25 multipoles (on average), and as Boud noticed with some weight, which I have to chack. In this way we get that few point like in the first picture I sent but the errors become smaller. They also drop all data above l approx 600. Well there is no easy way out, and much to do. Now I'm also thinking about calculating the power spectra directly from the map from MAP. Any ideas with aid of what to do it ? (witting a new code I give up - from time reasons ) bart. oh btw. that "vast f90" you mentioned is also commercial now. On Mon, 17 Mar 2003, Michal Frackowiak wrote: > you must have missed something important.... it's more than a game of > "show the diffrences in 2 pictures". it's a game of "check your code and > do it again..." ;-) > > szajtan odwieczny wrote: > > >well this is the thing I've been talking about on last thursday. > >Look at these two pictures. ;) > >Maeybe this kind of analysion is useless but surely it shows what problem > >we are dealing with here. > >On my plot (green dots) I chop off all negative values, all the values > >above 10000 for > >multipoles greater that 300 (which isn't a big crime), and throw out all > >points of which "errorbars" were bigger that the values itself. > >The red dots are raw data as it goes from LAMBDA. > > > >Well perhaps (I hope ;) somewhere among green dots are those we see at the > >picture from NASA. > > > > > >bartek > > > > > > > > ------------------------------------------------------------------------ > > > >------------------------------------------------------------------------ > > > >LISTNAME: shape-univ > >HELP: send an email to sympa(a)astro.uni.torun.pl with "help" > >WEB ARCHIVE: http://www.astro.uni.torun.pl/sympa/shape-univ/ > >UNSUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "unsubscribe shape-univ" > > > > > > > > >

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Re: new cmb code... (fwd)
by szajtan 17 Mar '03

17 Mar '03

ok. ciakawa koncepcja ale nie do konca rozumiem jak to dziala. masz obliczona i zparametryzowana (parametrami) w jakis sposob siatke modeli (o roznych parametrach kosmologicznych). tak ze na podstawie zadanych wartosci parametrow (nie kosmolog.) mozna szybko odtworzyc widmo. poszukiwane widmo w n wymiarowej przestrzeni parametrow jest otoczone przez 2^n modeli bazowych (o znanych zestawach wartosci parametrow kosmologicznych, i tych z parametryzacji). Mozna tez obliczyc jak daleko w przestrzeni parametrow kosmologicznych lezy poszukiwany model od modelow budujacych wezly siatki (tylko jak z tego skorzystac). Wiemy rowniez o ile roznia sie miedzy soba zestawy wartosci parametrow przypisanych do wezlow sieci. Ale nie chwytam kewstii obliczenia poszukiwanych wartosci parametrow na podstawie ktorych mozna odtworzyc widmo. Czyli innymi slowy jak to interpolowac skoro wiemy tylko ze poszukiwany zestaw parametrow lezy gdzies w oczku siatki parametrow.? > I have the code - not publicly available yet, but soon > it works as follows: > > 1. grid is produced and in nodes exact (well... cmbfast) cl spectrum is > calculated > 2. for every node some parametrisation of the spectrum is done (scaling, > chebyshev coeficients etc.) > 3. for given cosmo parms those parameters are interpolated and the > spectrum is reconstructed. > > quite simple. but faster than other interpolation methods (for gridded > models). > that is the main idea... > > polarisation also possible, but not yet implemented. > I can send you the code with the spectrum database if you wish. > > Bartosz Lew wrote: > > >ok, what's the catch ? > >and where is the code ? > > > >and btw. how this works ? > > > >On Mon, 17 Feb 2003, Michal Frackowiak wrote: > > > > > > > >>well, not completed, not even documented, but if anyone of you would > >>like to use it to reconstruct cmb spectrum REALLY FAST (within > >>miliseconds) - please try. > >>http://coyote.ncac.torun.pl/~michalf/cmbrecon/cmbrecon.php > >> > >>well - you can treat it as a preview of what is really about to happen. > >>a fast cmb-spectrum reconstruction code. with quintessence (or whatever) > >>included (soon also other scalar-tensor things). for generating grid: > >>server-client architecture, quite smart reconstruction algorithms.... > >>in case of interest/doubts/will to use - feel free to contact me. code > >>is quite complete and usable. > >> > >>michal frackowiak > >> > >> > >> > >> > >> > > > > > > > >------------------------------------------------------------------------ > > > >LISTNAME: shape-univ > >HELP: send an email to sympa(a)astro.uni.torun.pl with "help" > >WEB ARCHIVE: http://www.astro.uni.torun.pl/sympa/shape-univ/ > >UNSUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "unsubscribe shape-univ" > > > > > > > > > > > > ---------------------------------------------------------------------------- ---- LISTNAME: shape-univ HELP: send an email to sympa(a)astro.uni.torun.pl with "help" WEB ARCHIVE: http://www.astro.uni.torun.pl/sympa/shape-univ/ UNSUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "unsubscribe shape-univ" --------------r-e-k-l-a-m-a----------------- Tanie bilety lotnicze! http://samoloty.onet.pl

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map data
by szajtan odwieczny 15 Mar '03

15 Mar '03

well this is the thing I've been talking about on last thursday. Look at these two pictures. ;) Maeybe this kind of analysion is useless but surely it shows what problem we are dealing with here. On my plot (green dots) I chop off all negative values, all the values above 10000 for multipoles greater that 300 (which isn't a big crime), and throw out all points of which "errorbars" were bigger that the values itself. The red dots are raw data as it goes from LAMBDA. Well perhaps (I hope ;) somewhere among green dots are those we see at the picture from NASA. bartek

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about the variability
by Bartosz Lew 20 Feb '03

20 Feb '03

I was inspired by Magda's seminar this monday about the variability of css, gps or whatever. She said that variability is something like a hundret years. And then I thought: shouldn't it (the period) be corrected for the expansion of the universe since these objects happend to be so strongly redshifted ? Or maeybe this effect is negligible. bartek

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Fwd: The Oldest Light in the Universe
by Tomasz Laczkowski 12 Feb '03

12 Feb '03

NASA Science News for February 11, 2003 A NASA satellite has taken a picture of the Big Bang's ancient afterglow. Scientists have analyzed the data and learned that the universe is 13.7 billon years old (plus or minus 1 percent)and that the first stars appeared only 200 million years after the Big Bang. These results are a milestone in cosmology, says the NASA director of astronomy and physics. FULL STORY at http://science.nasa.gov/headlines/y2003/11feb_map.htm?list129344 <czosnek> \|/ (|||) " -

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all those constraints
by szajtan 15 Jan '03

15 Jan '03

Boud, I got your point about those constraints ;) (Maeybe there arose a little confiusion because I treat everything from the CMB point of view (CMB & rest of the world) as everything else (other methods) were just a kind of supplementary thing, some aid of narrowing our choices in space of parameters.) When we have a theory describing sth. with some free parameters, it doesnt give any constraints on unknown values until we know the values of those parameters. In that moment measurments enter the scene as some kind of calibration. Then we have a model and can derive whatever we want quantitatively. (e.g. LSS constraint - from assumption on model + "calibration" measurments ) But what if we had such a good theory that it doesnt need any additional measurmenst (except some well known physical constants) (nb measurments that introduce additional uncertanities) to predict the thing we're looking for. That would be a constraint of purely theoretical nature. (e.g. BBN constraint - only from physics of high energy particles - which happens to be more less consistent with constraints from observations of Ly_\alpha forest) Do you agree with this approach to the word "constraint" in astronomy ? Bartek ps. mentioned constraints include h uncertanity (which should be constrained externaly (eg. by SNIa constraint :)) (hmm but in this case I treat SNIa constraint supplementary not equivalently which at the beginning wasn't my intent) Maeybe this is just a nomenclature problem. We cannot deal with all methods of estimating parameters simultanously, so we pick one to ESTIMATE (DERIVE) parameters and then as an additional help treat all other estimations (comming from other methods) as CONSTRAINTS. I think thats it ! ***************r-e-k-l-a-m-a************** Chcesz oszczedzic na kosztach obslugi bankowej ? mBIZNES - konto dla firm http://epieniadze.onet.pl/mbiznes

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P(k)
by Bartosz Lew 07 Jan '03

07 Jan '03

what is the true meaning of P(k) ??? bartek

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Re: military masking net
by szajtan odwieczny 16 Dec '02

16 Dec '02

> As Michaウ said, it's true that the deviations from homogeneity are > small on scales anything much bigger than the Schwarzschild horizon of > a SMBH http://adjani.astro.uni.torun.pl:9673/zwicky/SuperMBH > > Another problem is that in the 2D balloon, the positive fluctuations > (the net) are connected in a continuous network, while the negative > fluctuations (lowest density) are unconnected, separated from one > another. Why do you consider that as a problem. That's just what we observe, isn't it. Those great cosmic scale filaments extending for hundredths of Mpcs. > > In the standard (3D) model, at early times the + and - fluctuations > are typically of the same typical sizes (e.g. from the hypothesis of > "gaussian fluctuations"), and the 2D topology of contours of constant > density ("genus analysis") is connected both for + and - fluctns. agreed but in time the curvature evolves, like everything else in this Universe. In time, because of gravity, matter tends to gather in a strings or clumps of higher density, and thus the curvature changes. > > If you consider all matter more dense than some value, > - a low density value gives a "gruyere (ser) topology" > - a critical density values gives a "sponge topology" what is the difference between these two ? is it only about the thickness of strings ? > - a high density gives a "meatball topology" > > This is impossible to do with a balloon, which is 2D, since the > topology of constant density "1-surfaces" is 1D. Let's consider a cross section of a large part of the universe with a plain. Then we take a pencil and draw all the contours of a constant matter density (= constant curvature) on that plane. We make a little step back to see the picture. We will see some distinctive pattern similar to the one observed for clusters of galaxies. This is the analogy to that net on the balloon. But strings of the net are not 1D but 2D (they have width) and in reality 3D, so for the fishing net we should sometimes even fill up some gaps not allowing the balloon the out stand. This I should call now a military masking net. The constraint of 2D balloon is as you mentioned that - fluctuations are separated. That's right but this is only because that on 2d surface a circle splits it into two regions. So in general this is not a good model. In 3D we can easily jump from one loop into another, unless there are walls (also those from that masking net :) but in 3D) - like The Great Wall. na razie bartek. --------------r-e-k-l-a-m-a----------------- Masz dosc placenia prowizji bankowi ? mBank - zaloz konto http://epieniadze.onet.pl/mbank

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fishing net
by szajtan odwieczny 13 Dec '02

13 Dec '02

hello everybody. Got an idea to share. Once upon a time I thought about such a thing. What was observed are the great voids (of size about 100 Mly in diameter or even bigger) separated by some cosmic great scale structures so it altogether looks like a soap foam. Assuming that the voids are empty, than the curvature of out local part of the Universe would look like - example in 2d: as we were pumping the balloon but confined by a fishing net which doesn't allow the surface of the balloon for free expansion, and in the end the balloon is quizzed by the strings of the net but it out stands in the holes of the net between the strings. In 3d this would be little more complicated to imagine but what do you thing about this ? with best holiday greetings Bartek --------------r-e-k-l-a-m-a----------------- Masz dość płacenia prowizji bankowi ? mBank - załóż konto http://epieniadze.onet.pl/mbank

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