Archive for March 2010

the honesty and fallibility of Scientists…!   1 comment

The honesty, fallibility of Scientists…!

The decade of galaxy formation: pitfalls in the
path ahead
Simon P. Driver
School of Physics, University of St Andrews, St Andrews, Fife, KY16 9SS
At the turn of the decade we arguably move from the era of precision cosmology to the era of galaxy formation. One approach to this problem will be via the construction of comprehensive galaxy samples. In this review I take the opportunity to highlight a number of challenges which must be overcome before we can use such data to construct a robust empirical blueprint of galaxy evolution. The issues briefly highlighted here are: the Hubble tuning fork versus galaxy components, the hierarchy of structure, the accuracy of structural decompositions, galaxy photometry, incompleteness, cosmic variance, photometric versus spectroscopic redshifts, wavelength bias, dust attenuation, and the disconnect with theory. These concerns essentially form one of the key motivations of the GAMA survey which, as one of its goals, will establish complete comprehensive kpc-resolution 3D multiwavelength (UV-Opt-IR-Radio) database of 250k galaxy systems to z < 0.5. Keywords: Galaxies PACS: 95.85.Kr
Following a decade of precision cosmology we move confidently into the decade in which we expect the process(es) of galaxy formation to become clear. The problem is well defined, how did baryonic matter assemble from the smooth distribution of neutral atoms at recombination to the 109M conglomerations of dust, gas, and stars that we see today. As we enter 2010 it is sobering to have to acknowledge that we do not yet have a cohesive model of galaxy formation [1] but rather an extensive body of empirical results from diverse approaches and which are often in conflict (does the IMF vary or not?, why does the cosmic star-formation history overpredict the local stellar mass density?, is the merger rate high or low? how exactly do AGN fit in?), and that these fragmented bodies of evidence sit uncomfortably with the obvious bottom-up mergerrich inference one naturally draws from the hierarchical-CDM paradigm (why does the majority of stellar mass sit in thin fragile discs if merging is the principle formation mechanism? why do both galaxies and AGN follow downsizing trends if the majority of massive systems form late?). At the outset of this journey it may be worth lightening our burden in two ways: firstly by acknowledging that probably a significant fraction of the current literature is in error (or at least dominated by poorly quantified systematics), and secondly that while hierarchical-CDM has been spectacularly successful at explaining the large-scale structure (> 1Mpc), the exact processes by which the baryons evolve remains a matter of prescriptive speculation. Monolithic collapse, feedback, merging, and hot/cold gas infall sure, but how much of each, and how are they regulated? The modeling, while The decade of galaxy formation: pitfalls in the path ahead January 22, 2010 1 a vital industry and visually spectacular, should not overshadow or overly influence the empirically driven process of discovery, but rather augment it. Nor should we be over-burdened with statistical precision given the domination of the data by hidden systematics. So many of the papers I referee focus exquisitely on the statistical errors while paying scant regard to the systematics errors, some of which are laid out here. Despite the plight of the world economies, we move into the new decade with a truly outstanding set of facilities coming online, for example: the refurbished HST, the HERSCHEL and WISE missions, the commissioning of VISTA and ALMA, and the opening up of 21cm studies beyond 12000km/s via ASKAP and MeerKAT, and in the longer term JWST, LSST, the SKA, and SNAP/DUNE/EUCLID (and too many more to mention). It is up to us not to fumble the opportunity this problem and these facilities provide, nor be overly fettered by the preconceptions we carry with us.
In this review I highlight ten practical issues which together convince me that low rather than high redshift is the place to start, that the time has come to truly embrace the multiwavelength approach, and that as much as we enjoy working in small teams the way forward is through large, open, and internationally cooperative collaborations.
Global versus component measurements
What exactly constitutes a galaxy? Is it a single entity best defined by global parameters (size, colour, flux), or a more complex construction of distinct components (bulge, bar, disc)? Which components are transient and which might represent a fundamental imprint of its formation history?
The legacy of Hubble’s initial classification scheme devised over 80 years ago lives on as galaxies are most often defined by their Hubble type (a global measure), but why? If the bulge and disc are co-eval entities whose properties are co-dependent then thismakes sense but, putting aside the question of pseudo-bulges, it is difficult to find any property beyond total luminosity which discs and bulges share. The ages, metallicities, dynamics, dust, star-formation rates are all distinct evoking the notion of a least two fully distinct evolutionary processes and pathways. A classical bulge shares more commonality with a giant elliptical than the disc so surely it is logical to isolate the bulges and discs and look for commonalities and correlations within each structural group rather than with Hubble type. Perhaps this is best illustrated through galaxy bimodality (see Fig. 1), where the blue cloud and red sequence (global measurements) provide a less clear distinction than that provided by the bulges and discs (component measurements). As a community we know this deep down but the blue/red mantra along with the Hubble Tuning fork is proving hard to leave behind.

Is Science Nearing Its Limits ?
Summarizing Dialogue Jean-Pierre Luminet
Laboratoire Univers et Théories, CNRS-UMR 8102,
Observatoire de Paris, F-92195 Meudon cedex, France
In 2007 an international conference engaged a reflection on the present conditions for sciences and scientific practice, to initiate a dialogue between science, philosophy, epistemology and sociology. Starting from many examples taken from the history of sciences and the present status of astrophysics, cosmology and fundamental physics, I analyze various issues such as the possible limits of theoretical and technological advances, the paradox of non-verifiability in string theory, incompleteness, the role of imagination in scientific research along with educational aspects, the epistemological value of the Ockham’s razor principle for constraining theories, and our undersanding of man’s place in Creation.

Is the cosmological “constant” a nonlocal quantum
residue of discreteness of the causal set type?⋆
Rafael D. Sorkin
Perimeter Institute, 31 Caroline Street North, Waterloo ON, N2L 2Y5 Canada
and Department of Physics, Syracuse University, Syracuse, NY 13244-1130, U.S.A.
address for email:
The evidence for an accelerating Hubble expansion appears to have confirmed the heuristic prediction, from causal set theory, of a fluctuating and “ever-present” cosmological term in the Einstein equations. A more concrete phenomenological model incorporating this prediction has been devised and tested, but it remains incomplete. I will review these developments and also mention a possible consequence for the dimensionality of spacetime.

…we do not know all about ourselves and life on Earth…!
…and they expect to determine the Universe and Galaxies…!
mainly because of the phenomena of basic matter being too small,
that surpasses even the most powerful “electron microscope”…!
and that the “indirect methods used” are not precise enough for
exactly this…! or viceversa, I.E.: too big…!
…not to mention, errors in obtained and calculated data…!
…that a lot of Science theories need to be at least “revised” !



Posted 03/29/2010 by abiteinthechunk in Uncategorized

news of the day…   Leave a comment

Grass-hoppers and yummy…!

Bees and honey…!

Tomatoes and bio-engineering…!

Quote of the Day
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
– Max Planck [Mon29Mar2010]

Posted 03/29/2010 by abiteinthechunk in Uncategorized

…Thanks GOOGLE on the day of PI…   1 comment

Book of Pure Logic
and the amazing never done
graphical low error calculation
of a closer range of the value
of pi = 3.1415……………………..

Thanks GOOGLE on the day
of PI…

Posted 03/14/2010 by abiteinthechunk in Uncategorized

…doomsday vaults and the movie 2012…   Leave a comment
World Seed Vault Reaches Half-Million Mark
Posted on: Friday, 12 March 2010, 06:50 CST
The foundation that oversees the Svalbard Global Seed Vault said Thursday that the unique Arctic “doomsday” stockpile of all the world’s crop seeds has reached the half-million species mark.
…i wonder if a world human vault will ever be thought of !!!
…because for some magical reason and/or copyright or “originality” with
my book of pure logic, the movie 2012, has used “ark(s)” for human
“doomsday” recovery ! ! !

Posted 03/12/2010 by abiteinthechunk in Uncategorized

  1 comment

World-true-right-correct MYSTERIES,
by no means “evolution”…!

…The alignment of the fantastic ancient rock statues
and buildings, of Easter Island, the Great Pyramids
of Giza, and others. But not the Mexico pyramids,
and/or not others, is significant.
…Also the Worlds axis of rotation inclination of 23deg.,
also is more so.
…I thought I heard and saw a recent news of an
Ar(c)tic glacier becoming a huge “IceBerg”…! But I
could not find it online…!

…No fear “super-man/woman” is hear…!

Posted 03/01/2010 by abiteinthechunk in Uncategorized