A&C reference library [Archive]

marcus

Jan26-04, 06:04 PM

Nereid kindly provided a link to this article about
a wide-angle deep survey of the universe called GEMS
http://skyandtelescope.com/news/article_1152_1.asp

GEMS covers a patch of sky as big as the full moon
and took thousands of images in that patch
and made a mosaic picture of that patch which is
real deep, going way back in time, so you see
galaxies forming and colliding and evolving.
The article Nereid shows a portion of the picture.
The total GEMS picture has some 3 billion pixels.

------------------------

Dark matter:
Here's another Nereid link to a dark matter article (mapping it in a cluster by observing lensing)
http://www.esa.int/export/esaCP/SEM...tureWeek_0.html
------------------------
Neutrino astronomy:
Has a big future potential in observational cosmology. Wolram provided these neutrino-related links:

http://www.space.com/scienceastrono...nos_030716.html
this gives the AMANDA2 neutrino sky map---the obseratory down near south pole.

http://www.lns.cornell.edu/spr/2003-07/msg0052565.html
Basic facts/estimates about the cosmic neutrino background presented
by Ted Bunn, one of the moderators on Usenet sci.physics.research.

---------------------------
High-energy Cosmic Rays:
A great survey article about high energy cosmic ray observations
(another window for observational cosmology to look thru)
Floyd Stecker
"Cosmic Physics: the High Energy Frontier"
http://arxiv.org/astro-ph/0309027

marcus

Jan26-04, 06:09 PM

two good online cosmology calculators:

Ned Wright's
http://www.astro.ucla.edu/~wright/CosmoCalc.html

Siobahn Morgan's
http://www.earth.uni.edu/~morgan/ajjar/Cosmology/cosmos.html

homepage for Siobahn in case you want to see who she is
http://www.earth.uni.edu/smm.html
homepage for Ned in case you want to see who he is
http://www.astro.ucla.edu/~wright/intro.html

-------
Martin Bojowald
http://arxiv.org./abs/astro-ph/0309478
"Quantum Gravity and the Big Bang"
General Relativity had a glitch and
quantizing the theory fixed the glitch so
it no longer predicts a moment of infinite
density and curvature (a type of singularity).
Evolution prior to big bang is shown in some
of the articles cited in this brief survey.
---------

Labguy provided news of a recent test of General Relativity
(which GR passed with flying colors) a binary pulsar:

http://www.astro.ucla.edu/~wright/cosmolog.htm#04Dec03

The technical article about the binary pulsar
and the most stringent verification of GR to date is:

http://arxiv.org/astro-ph/0401086

----------

marcus

Jan26-04, 06:28 PM

Useful constants:

One parsec = 3.857E16 meters

Newton's G = 6.6742E-11 cub.meter/sq.second kg

Best current estimate of Hubble parameter H = 71 km/s per Megaparsec

Critical energy density derived from that = 0.85 joule per cubic km.

In standard (SI) metric units H = 2.301E-18 per second

H reciprocal, the "Hubble time" parameter, is 4.3E17 seconds.
(As it happens this is roughly the same as the age of the universe.)

The standard formula for calculating the critical density (so-called "rho crit") is

\rho_{crit} = \frac{3c^2H^2}{8\pi G}

If you plug in the values for G, c, and H given here, it works out to 0.85 joule per cubic kilometer.

This is the average energy density that is theoretically needed for space to be flat rather than positively or negatively curved. Since WMAP observations of the CMB indicate that it is flat or very nearly so, this is the density usualy assumed.
When people say the dark energy is 73 percent they mean of this.
Or dark matter is 23 percent, it is of this 0.85 joules per cubic km.
Or ordinary visible matter is 4 percent, it is likewise.

marcus

Jan26-04, 06:39 PM

Lineweaver's article is also online in HTML at a Caltech site
and this is sometimes handy because you can link to a particular
page or Figure, rather than to the whole PDF file. For instance
his "Size and destiny of the universe" Figure 14 is immediately
accessible in two places

Figure 14 medium scale, with caption and another figure:
http://nedwww.ipac.caltech.edu/level5/March03/Lineweaver/Lineweaver7_7.html
Figure 14 larger scale, without caption:
http://nedwww.ipac.caltech.edu/level5/March03/Lineweaver/Figures/figure14.jpg

marcus

Jan26-04, 06:48 PM

Originally posted by cragwolf
Even if Omega was precisely equal to one, you could still have a finite universe: in this case, its topology would have to be multiply-connected. For example, a 3-torus, a kind of 3-dimensional version of the surface of a doughnut, is flat everywhere, but its volume is finite. General relativity (and hence the standard big bang model) has nothing to say about topology. Perhaps this is a limitation, perhaps not. Anyway, here are some articles on the subject of cosmic topology:

The Topology of the Universe (http://arxiv.org/abs/astro-ph/0010185) by Boudewijn F. Roukema

Topology of the Universe: Theory and Observations (http://arxiv.org/abs/astro-ph/9901364) by Jean-Pierre Luminet and Boudewijn F. Roukema

Cosmic Topology (http://arxiv.org/abs/gr-qc/9605010) by M. Lachieze-Rey and J.P.Luminet

Topology and the Cosmic Microwave Background (http://arxiv.org/abs/gr-qc/0108043) by Janna Levin

Constraining the Topology of the Universe (http://arxiv.org/abs/astro-ph/0310233) by Neil J. Cornish, David N. Spergel, Glenn D. Starkman and Eiichiro Komatsu

marcus

Jan26-04, 06:53 PM

There's an especially good PF thread about the expansion of space. It is wideranging and touches on a bunch of cosmology and general astronomy type issues. In this thread Nereid has a good short essay on dark matter.

http://www.physicsforums.com/showthread.php?s=&postid=135705#post135705

In the same thread Nereid supplied some source links, which I will exerpt from one or two of her posts and include here:

"...This page, brought to PF members by ranyart, is a good place to start:
http://www.solstation.com/x-objects/greatatt.htm
...
...

I don't have any good ones immediately to hand. However, this site has many excellent links:
http://msowww.anu.edu.au/2dFGRS/

In particular, this paper gives a flavour of how the work is done: "The 2dF Galaxy Redshift Survey: Cosmological Parameters and Galaxy Biasing", Ofer Lahev, in astro-ph/0205382

A couple more:
http://antwrp.gsfc.nasa.gov/apod/ap011219.html
and if you click on the 'computer simulation' link in this page, you will get....
...
...

A pretty picture:
http://antwrp.gsfc.nasa.gov/apod/ap030611.html
...
..."

marcus

Jan26-04, 07:15 PM

Jimmy supplied these mosaic pictures of Europa and Jupiter

http://members.aol.com/jrzycrim01/images/Europa.jpg
http://members.aol.com/jrzycrim01/images/Europa2.jpg

They are pretty remarkable.
----------------------------------------

Nereid supplied a good general purpose NASA link about the moons and the Jovian system in general

http://galileo.jpl.nasa.gov/moons/moons.html

Also some more specialized links concerning Io's ice
covered ocean and concerning impact basins (of which Callisto has
a couple of examples)
http://www.lpi.usra.edu/research/europa/thickice/
http://www.solarviews.com/cap/index/impactbasin1.html

----------------------------------------

Enigma supplied this link to tabulated data on the Jovian moons:

http://www.the-planet-jupiter.com/moons-facts-sheet.html
----------------------------------------

Here's a useful source about gravity assist maneuvers

http://cdeagle00.tripod.com/omnum/flyby.pdf

It gives a formula for the maximum turn angle

2arcsin \frac{1}{1+rv_{oo}^2/\mu}

possible flying by a body with radius r and gravitational parameter(GM) equal to mu. Here v-infinity is the speed of approach at infinity. This can be rewritten in terms of v-infinity and v-circ, the circular orbit speed at the body's surface:

2arcsin \frac{1}{1+v_{inf}^2/v_{circ}^2}
-------------------------------------------------

marcus

Jan26-04, 07:19 PM

http://www.solarviews.com/raw/jup/callisto.gif

it's big and has a lot of detail

marcus

Jan27-04, 01:39 AM

Mark Trodden and Sean Carroll just posted an 82-page
"Introduction to Cosmology"
http://www.arxiv.org/astro-ph/0401547

It's a pedagogical paper summarizing a series of lectures for advanced graduate students, delivered as part of the 2002 and 2003 Theoretical Advanced Study Institutes in elementary particle physics (TASI) at the University of Colorado at Boulder.

It seems that nowadays grad students in particle physics are often eager to move into astro/cosmo research----sometimes called "astroparticle-physics". So this course must be in demand at TASI. It certainly is not a course for beginners, in spite of the name "Introduction".

Sean Carroll is one of half a dozen most prominent cosmologists worldwide. These notes could be useful and informative for the right reader, so I list them. They just came out today. Personally I prefer Chuck Lineweaver's and Ned Wright's more popular and intuitive style. this is more elite high-academic style.

cragwolf

Jan27-04, 01:47 AM

A very nice web site for amateurs like me (I especially like the FAQs):

http://www.astronomycafe.net

Ned Wright's calculator has been mentioned, but here are links to his brilliant tutorial and FAQ:

http://www.astro.ucla.edu/~wright/cosmolog.htm

http://www.astro.ucla.edu/~wright/cosmology_faq.html

The NASA/IPAC extragalactic database contains data and literature on extragalactic objects:

http://nedwww.ipac.caltech.edu

There's also an excellent knowledge base, where many articles on various astronomical subjects are kept:

http://nedwww.ipac.caltech.edu/level5/

Some pretty cool lecture notes on galaxies:

http://www.astr.ua.edu/keel/galaxies/

This is one place I get my astronomy news from:

http://www.spaceflightnow.com/news/index.html

marcus

Jan29-04, 04:04 PM

Cragwolf thanks for posting these links at the A&C reference shelf!
---------------------------------
Recently Gale17 asked about introductory Astro material and chroot (Warren) and Phobos, as well as others responded. Warren teaches an extension course in Astro for continuing ed so here are his course notes among other things:

Warren says
http://www.skymaps.com
has a good monthly star map with lots of observing hints, for free.

He also says go to star parties (nerds with telescopes hanging out for an evening in a parking lot somewhere), which are remarkably educational.

Here are his course notes:

http://users.vnet.net/warrenc/astro/introduction.pdf

http://users.vnet.net/warrenc/astro/telescopes.pdf

http://users.vnet.net/warrenc/astro/mythology.pdf

http://users.vnet.net/warrenc/astro/stars.pdf

Phobos says:

Don't buy a telescope to start off. Start by learning the constellations (in the sky, not just on paper). You can get an updated sky map cheaply in the monthly magazines like Sky&Telescope or Astronomy (or even downloaded free from the internet). The first optical step should be a good pair of binoculars (not too expensive). That alone should cover you for a year or two of fun.

After that foothold, look for a local astronomy club (I can't recommend one for NH, but this looks promising...

http://www.nhastro.com/index.html

Check out local planetariums & observatories (sometimes they allow the public access to their telescopes).
--------end quotes from Warren and Phobos--------

since the Earth is one of the planets we should have some references with facts about the Earth (even tho this is not Astronomy as usually understood) and I dont know what to suggest, but a PF poster recently cited the CIA World Factbook, maybe it will do:
http://www.cia.gov/cia/publications/factbook/

marcus

Jan29-04, 04:41 PM

the expansion of space (socalled "hubble flow") defines a stationary reference frame. being at rest with respect to hubble flow is the same as being at rest with respect to the Cosmic Microwave Background. CMB it gives an absolute notion of rest which cosmologists use a lot and an interesting question is, in these absolute terms, how fast and in what direction is our solar system moving?

the COBE result reported in 1996 is that it is moving about one thousandth of the speed of light in the direction of the constellation Leo

there is a doppler hotspot in the CMB in Leo
and 180 degrees in the opposite direction there is a doppler coldspot
The Microwave Background coldspot would be in Aquarius, I guess.

COBE is authoritative, so here is the link to its 1996 report

http://arxiv.org/PS_cache/astro-ph/pdf/9601/9601151.pdf

"The Dipole Observed in the COBE DMR Four-Year Data"
-----------------------------

Now astronomers use several different systems of coordinates and
COBE reported the Microwave Background hotspot in two different systems, ordinary celestial and galactic.

ordinary:(11 h 12 m, -7.22 degrees)
galactic: (264 degrees, +48 degrees)

they actually gave more decimal places and error bounds.
The speed they gave was equivalent to 1.231 +/- 0.008 thousandths of c, but I would just round it off to 1.23 thousandths.

If you want to convert between ordinary coords and
galactic coords, you can use something online at
Johns Hopkins University. Professor Murphy's online calculator.
Murphy's Galactic Gizmo
http://fuse.pha.jhu.edu/support/tools/eqtogal.html

-----------------------------
If you go out to look at stars between 10 and 11 PM in
the evening then you probably can see Leo any clear evening
Feb thru May. It's where we're going. there's no destination, only
a direction. and the speed is a thousandth of light's

Here is a star map with the temperature of the Background as an overlay, showing the hotspot. So you can see the stars around Leo and a kindof contour map of temp:

http://aether.lbl.gov/www/projects/u2/

the hotspot is about 3.5 millikelvin above the average temp of the Background

marcus

Jan29-04, 04:59 PM

we belong to a little fleet of galaxies called the Local Group
the main ones are Milky and Andromeda but there are a dozen or so more
(I forget how many)
and sometimes people wonder about the course this small fleet of galaxies is steering----what it the speed and direction is in space

of course that is relative to the Cosmic Microwave Background, the standard frame for cosmology (also called the "Hubble flow")

This link tells the Local Group speed and direction

http://www.arxiv.org/abs/astro-ph/0210165

The speed they give is 627 km per second
This is 2.09 thousandths of the speed of light
or roughly two thousandths (easier to remember).

The direction is in the constellation Crater
and since Crater is small and dim it is easier to find
if you look for a diamond shape called Corvus
which is practically in the same direction.
You see Corvus to the south on spring evenings
like april and may is a good time and it will be
about on the meridian (the overhead northsouth line)

Thats where Milky and our neighbors are heading, but
Andromeda is behind us and moving faster so it is going
to catch up eventually which will mess up both spirals some.

Janus

Jan29-04, 05:16 PM

A nice coleection of info on the Solar System.

http://seds.lpl.arizona.edu/nineplanets/nineplanets/nineplanets.html

Including these appendixes:
http://seds.lpl.arizona.edu/nineplanets/nineplanets/data.html

http://seds.lpl.arizona.edu/nineplanets/nineplanets/data1.html

http://seds.lpl.arizona.edu/nineplanets/nineplanets/data2.html

marcus

Jan29-04, 05:38 PM

Janus thanks for posting the Solar System links!

Tsunami recently posted this GLAST link

http://glast.gsfc.nasa.gov/

She says that just this month (January 2004) the launch was postponed to February 2007. Another year delay. I am acting as reference librarian here and should not editorialize too much.

However notice that Fundamental Physics has acquired a new name.
It is no longer "high-energy particle physics" and no longer
so tied to the great accelerators.
The name of the Fundamental Physics game is now
cosmology and astroparticle physics

Lots of former HEP people are migrating.

GLAST (gammaray large array space telescope) is for seeing gammaray bursts---explosions bigger than supernovas, maybe from two neutron stars colliding to form a black hole.

these new space instruments are like the accelerators of the Fifties thru Seventies. they should not take second place to manned space projects which are Political Soap Opera compared with fundamental science.

Tsunami thanx for the link

marcus

Jan31-04, 04:16 PM

Gale17 asked about online stuff for getting an introduction
to basic general astronomy and
nymph suggested a monthly online course

"You can find free Monthly Astronomy Lessons at.."
http://www.synapses.co.uk/astro/

marcus

Feb1-04, 09:35 PM

this site seems to have current status of the two rovers
http://marsrovers.jpl.nasa.gov/home/index.html

if you know of a site that's more informative about their status, or the data and pictures they're transmitting, you are most welcome to post it

marcus

Feb2-04, 01:52 PM

Alan Guth has a couple of recent ones (2003)

"Time since the beginning"
http://arxiv.org/astro-ph/0301199
(quote: "'eternal' inflation...proposes that our universe evolved
from an infinite tree of inflationary spacetime")

"Inflation and cosmological perturbations"
http://arxiv.org/astro-ph/0306275

Stephen Hawking has a recent one (2003)

"Cosmology from the top down"
http://www.arxiv.org/ftp/astro-ph/papers/0305/0305562.pdf

Alan Guth has an older, more wide-audience, talk too (2001)

"Eternal Inflation"
http://arxiv.org/astro-ph/0101507

-------------

In eternal inflation an inflating patch expands so fast that even tho the vacuum energy driving it decays exponentially (causing pockets of non-inflating space to form) there is always a larger patch still inflating. Once, by some quantum mechanical accident, this process begins, it must continue forever, and create a welter of pockets of space that have finished inflating.

In a curious way, it appears as if the "eternal" inflation story was invented to take care of the the question of how inflation gets started-----in all spacetime it never has to start more than once (by some no-matter-how-unlikely quantum hiccup) and once started goes on forever making jillions of universes like ours. So the question of how it got started in OUR little universe is dispelled.

If this "starting problem" had never appeared---say the standard models of physics and cosmology had, from the outset, always predicted an inflaton field causing brief exponential expansion and then decaying---then quite possibly no one would have bothered to think up this "eternal" tree of pocket universes outside our own.

Hawking's critique of the "eternal" scenario is an example of someone who disposes of it because he thinks he doesnt need it---he thinks he has a way to describe how what we see came about (without going outside the universe we see).
-------------------

For a mainstream cosmologist's view (simple oneshot inflation, no fancy theory)

Lineweaver
"Inflation and the Cosmic Microwave Background"
http://arxiv.org/astro-ph/0305179
------------------------

Another recent paper (November 2003)

Tsujikawa, Singh, Maartens
"Loop quantum gravity effects on inflation and the CMB"
"Time since the beginning"
http://arxiv.org/astro-ph/0311015

Loop gravity predicts a quantum bounce with a peak density and predicts this will trigger inflation, so no other story is needed about how it gets started. So topic of "eternal" never comes up.
For other papers see references in this one. Tsujikawa and Maartens are string theorists---this is their only contribution so far to Loop gravity---so their examination of the loop gravity mechanism for inflation is especially interesting I think.

marcus

Feb5-04, 12:09 PM

Wolram supplied a link (in Astrophysics forum) about
an interesting object. It is a spinning black hole that
periodically produces jets along its axis of rotation

http://heasarc.gsfc.nasa.gov/docs/xte/learning_center/discover_0198.html

there are some schematic pictures describing what is going on
and some lightcurves, and an audio soundfile that I havent listened to.

marcus

Feb5-04, 12:35 PM

http://www.arxiv.org/abs/astro-ph/0402083

this recent article might be a useful source for someone interested
in neutrino astronomy----AMANDA, icecube, the future and an
overall perspective about it.

"High energy neutrino astronomy"
can't think of the author's name just now

Floyd Stecker's article also covers neutrino observation, there's a link to it earlier in the thread

Nereid

Feb6-04, 05:18 PM

If you are an amateur astronomer (or thinking about it), and are wondering about CCDs, what they can do, how you can use them, etc, I recommend you spend 30 minutes or so reading through the AAVSO* "CCD Observing Manual":
http://www.aavso.org/observing/programs/ccd/manual/index.shtml#new

This has got to be the best ~30 min intro to the subject on the web.

It covers telescopes, CCDs, computers, software, and (most important for real individuals) the actual time and $$$ that is involved in actually *doing* this stuff!

*despite its name - American Association of Variable Star Observers - it's a truly international non-professional organisation, with an incredibly strong contribution from 'down under' - yah Aussies!

marcus

Feb6-04, 05:55 PM

thanks Nereid! looking forward to more of your links
on this "reference shelf" thread.

marcus

Feb14-04, 01:18 AM

This article by Lev Okun has been cited several times IIRC,
most recently by pmb_pby:

http://xxx.lanl.gov/abs/physics/9907017

this is the article about the gravitational redshift.
Lev Okun's 1989 article about the concept of mass
is only available in hard copy AFAIK. If someone knows
where it has been put online please let us know.

marcus

Feb14-04, 09:51 PM

http://arxiv.org/astro-ph/0402278

Tamara Davis thesis (advisor Charles Lineweaver)
"Fundamental Aspects of the Expansion of the Universe and Cosmic Horizons"

------------------------
http://arxiv.org./abs/astro-ph/0310808

Davis and Lineweaver
"Expanding Confusion:common misconceptions of cosmological horizons and the superluminal expansion of the Universe"

Lineweaver and Davis are at the University of New South Wales.
Lineweaver was one of the leaders of the COBE project (satellite
mapping the cosmic microwave background in the 1990s)
----------------------------
http://arxiv.org./abs/astro-ph/0401024
Lineweaver et al
"The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way"

9 pages, 4 figs. Published in Science, 2 January 2004

We modeled the evolution of the Milky Way to trace the distribution in space and time of four prerequisites for complex life: the presence of a host star, enough heavy elements to form terrestrial planets, sufficient time for biological evolution and an environment free of life-extinguishing supernovae. We identified the Galactic habitable zone (GHZ) as an annular region between 7 and 9 kiloparsecs from the Galactic center that widens with time and is composed of stars that formed between 8 and 4 billion years ago. This GHZ yields an age distribution for the complex life that may inhabit our Galaxy. We found that 75% of the stars in the GHZ are older than the Sun.

marcus

Feb18-04, 09:17 AM

http://nedwww.ipac.caltech.edu/level5/cos_par.html
http://nedwww.ipac.caltech.edu/level5/toc.html
http://nedwww.ipac.caltech.edu/leve...ary/frames.html

"Level 5 knowledgebase for extragalactic astronomy and cosmology"
it has essays on various topics by famous people
and a glossary
it is put together by a CalTech guy
the site has one many awards
and is supported by prestigious funding agencies
arivero reminded me about this site

marcus

Feb19-04, 07:03 PM

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html

this java applet goes from a view of the milkyway galaxy down
to subatomic particles in steps of ten
you can control it and back it up if you want
or just let it go

I cant say how this compares to other things like it that
will play on your computer. A friend recommended it.
anyone have other visuals they especially want to recommend?

marcus

Feb24-04, 01:37 PM

There is a new paper posted by Eric Linder
"Probing Gravitation, Dark Energy, and Acceleration"

http://arxiv.org./astro-ph/0402503

it explores the different explanations of accelerating expansion

cosmological constant (w = -1)
quintessence
some braneworld picture (which he says tends to imply
that w > - 0.7 under realistic assumptions about the density of matter)

he seems fairly sanguine about upcoming possibilities for comparing and distinguishing between models, as the history of the universe's scale-factor becomes a(t) better-known

reputable discussion of the various explanations for acceleration

marcus

Feb26-04, 06:11 PM

It was Ranyart who mentioned this one

http://arxiv.org/hep-th/0311030

"Black Holes in de Sitter Space: Masses, Energies and Entropy Bounds"

a paper by Corichi and Gomberoff analysing a black hole (entropy, hawking radiation, evaporation and all that) in the "isolated horizon" situation.

In that situation there are two horizons---the BH's own event horizon and a cosmological horizon (from beyond which nothing can ever come)
Ashtekar has been doing a lot of research on this situation. It is realistic in the sense that assuming a positive cosmological constant we really do have a cosm. horizon. Accelerating expansion causes it.

Having the other horizon helps limit things and makes it possible to do analysis where one could not before (with the BH just sitting by itself in an infinite expanse of space).

A couple of other BH articles came to light recently
-------------------

Maulik Parikh
http://arxiv.org/hep-th/0402166
"Energy Conservation and Hawking Radiation"
---------------------

Maulik Parikh and Frank Wilczek
http://arxiv.org/hep-th/9907001
"Hawking Radiation as Tunneling"

ranyart

Feb27-04, 12:09 AM

Originally posted by marcus
It was Ranyart who mentioned this one

http://arxiv.org/hep-th/0311030

"Black Holes in de Sitter Space: Masses, Energies and Entropy Bounds"

a paper by Corichi and Gomberoff analysing a black hole (entropy, hawking radiation, evaporation and all that) in the "isolated horizon" situation.

In that situation there are two horizons---the BH's own event horizon and a cosmological horizon (from beyond which nothing can ever come)
Ashtekar has been doing a lot of research on this situation. It is realistic in the sense that assuming a positive cosmological constant we really do have a cosm. horizon. Accelerating expansion causes it.

Having the other horizon helps limit things and makes it possible to do analysis where one could not before (with the BH just sitting by itself in an infinite expanse of space).

A couple of other BH articles came to light recently
-------------------

Maulik Parikh
http://arxiv.org/hep-th/0402166
"Energy Conservation and Hawking Radiation"
---------------------

Maulik Parikh and Frank Wilczek
http://arxiv.org/hep-th/9907001
"Hawking Radiation as Tunneling"

This paper may allready be on PF somewhere, but this is a recent update:http://uk.arxiv.org/PS_cache/gr-qc/pdf/0402/0402009.pdf

Its quite an interesting read, gives detailed and clear perspective outlines, and the citation/referal pages are a who's who of current Quantum Gravity community

marcus

Mar2-04, 11:20 PM

Meteor pointed us to the mid-pyrenees observatory
finding a z = 10 galaxy
(and GedankenDonuts gave a link too) then Nereid came up with
the scientific article co-authored by Roser Pello

http://www.edpsciences.org/papers/aa/pdf/press-releases/aaga201.pdf

here is a picture of Roser, she looks pleased to have found the galaxy
http://webast.ast.obs-mip.fr/people/roser/

z=10 means that the universe has expanded 11-fold since
the light issued from that galaxy

so while the light was traveling to get to us, distances between things became eleven times larger.
that means it was a long time that the light was traveling, estimated 13.2 billion years

for a calculator to calculate stuff like that try
Siobahn Morgan's online cosmology calculator

http://www.earth.uni.edu/~morgan/ajjar/Cosmology/cosmos.html

homepage for Siobahn also with photo
http://www.earth.uni.edu/smm.html

putting in the usual 71 for H, 0.73 for Lambda and 0.27 for matter density, we get that the object Roser and the others found is currently 31.5 billion light years from us and receding at a speed of 2.3 times the speed of light

marcus

Mar9-04, 10:17 AM

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=34567
link courtesy Nereid, see her thread on this
"Osiris, a chthonian planet"
http://www.physicsforums.com/showthread.php?s=&threadid=13989

Janus

Mar15-04, 07:15 PM

Here's a nice Ephemeris Generator:

http://ssd.jpl.nasa.gov/cgi-bin/eph

wolram

Mar24-04, 01:12 PM

http://map.gsfc.nasa.gov/

some major and minor observatories, loads of links and info.

wolram

Mar24-04, 01:33 PM

http://www.school-for-champions.com/science/gravity2.htm

gravity equations lots of basic stuff.

wolram

Mar24-04, 02:01 PM

http://www.go.ednet.ns.ca/~larry/stars/starform.html

how stars are formed.

marcus

Mar24-04, 03:16 PM

wolram thanks for adding these links to the reference thread!
the interactive tutorial on gravity is a good idea
(with the mild online quizes to self-check understanding)
the history of formation of a star like the sun was
informative (at least for me) by telling central and surface temperatures at each stage and time in that stage and
plotting the protostar's approach to the main sequence on the HR diagram---gives a more detailed story helping imagine how the
sun came into being

wolram

Mar26-04, 12:19 PM

http://calspace.ucsd.edu/virtualmuseum/Glossary_Astro/gloss_a-f.shtml

GLOSSARY of terms.

marcus

Apr17-04, 01:28 AM

http://relativity.livingreviews.org/Articles/lrr-2001-4/

Clifford Will
Confrontation between General Relativity and Experiment
----------

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

Tom Roberts
Experimental Basis of Special Relativity
(from the Physics FAQ)
-----------

these are two links that Russ says Nereid supplies in her posts
responding to folks challenging GR and SR

meteor

Apr17-04, 10:41 AM

This paper seems interesting:
"Distance measures in cosmology"
David W. Hogg
http://arxiv.org/abs/astro-ph/?9905116

It must be good given that I really enjoyed the pdf course of special relativity of D. Hogg

marcus

Apr28-04, 08:11 PM

A recent set of lectures
http://www.mpia-hd.mpg.de/homes/rix/Lecture.html

Rix is director of the MPI for Astronomy
the lectures are winter 2003-2004
by Matthias Bartelmann

a recent article by Alan Guth
"Inflation"
http://arxiv.org./astro-ph/0404546

a new pedagogical paper on the standard view of
the early universe
seems clearly written, 44 pages
by David Langlois
http://arxiv.org./hep-th/0405053

marcus

May14-04, 04:06 PM

the Friedmann equations (the basic equations of cosmology)
just to have them handy for reference:

in units where c = 1:

\frac{a''}{a} = - \frac{4\pi G}{3}(rho + 3p)

(\frac{a'}{a})^2 = \frac{8\pi G}{3}rho - \frac{k}{a^2}

on first encounter with F. eqn. people often get confused by
the fact that Greek letter rho (for density) looks like Roman p (for pressure)
so I spell rho out here instead of using the symbol. The rho and p here are inclusive of all forms of energy from ordinary matter to dark energy.

k is a spatial curvature term, often set to equal zero since the universe is seen to be spatially flat either exactly or to a good approximation

a is the spatial scale factor in the standard cosmology metric (socalled FRW metric) and a increasing means distances between points are getting larger IOW space is expanding. The prime is its time derivative, so a' is rate of increase of a and a'' is a measure of acceleration.

----------very sketchy discussion--------
in cosmology almost nothing has pressure besides the dark energy
and for dark energy the most commonly assumed equation of state is
pX = - rhoX
(thats what you get from a vacuum energy or a constant energy density associated with the cosmological constant, the typical dark energy idea)

IIRC the estimated average density for our universe at the present is
about 0.83 joules per cubic km
this includes the estimates of everything: visible matter, unseen matter, dark energy, light energy, neutrinos etc.
this energy density accords with the observed expansion rate and the observed flatness.

Dividing a'' by a makes the arbitrary length unit go away and you get a measure of acceleration that is just a reciprocal time squared.

Dividing a' by a gets rid of the length unit and after squaring you have
a reciprocal time squared there too. So in both equations the LHS is a reciprocal time squared.

rho and p have the same units (the unit of energy density is the same as that of pressure, in any coherenent system of units)
and multiplying by G will give, on the RHS as well, a reciprocal time squared

the point about dark energy is that as an energy density it contributes to the slowing of expansion by contributing to rho
just like any other type of energy including matter
so by contributing to rho, dark energy favors contraction

but dark energy is 3 times more influential as a pressure and in that way (by the negative pressure) it makes the whole RHS of the eqn positive and favors accelerating expansion

sol2

May14-04, 04:49 PM

Here we provide you with an exercise to explore the possible universes governed by the Friedmann equation (equation (11.19) in the text). We use a simple applet to integrate the Friedmann equation for a range of models. (Note that this requires Java running on your browser.) On the applet below you can enter a value of Omega (density of the universe), a value of Lambda (the cosmological constant), and select a curvature (positive, zero, or negative). Note: This exercise provides a qualitative feel for the relative behavior of the Friedmann equation with respect to cosmological parameters. It does not provide detail models for comparison with observed cosmological values of omega or hubble time

http://astsun.astro.virginia.edu/~jh8h/Foundations/Friedmann.html

marcus

May15-04, 06:13 PM

sounds like fun, sol
here is a source on neutron stars
including detailed accounts of the stages of
Type II supernova collapse and the layer structure
of a neutron star
http://arxiv.org./astro-ph/0405262

sol2

May17-04, 10:38 AM

Thank you Marcus,

I have been developing well with this kind of information (http://online.itp.ucsb.edu/online/plecture/thorne/). I hope others will benefit too.

http://online.itp.ucsb.edu/online/plecture/thorne/oh/08.gif

Some will appreciate the understanding there, of all the maths. Klein's ordering of Geometires as they have been shown through Patricias link of what is required of String theory in terms of those maths would have been laying one over the other, but in the Bose Nova, a culmination?

With Omega, critical density must still play a part in our understanding of this dynamical world in the classical realities? But when it comes to QM, how shall we understand the issues presented in cosmology, might also speak to QM as well?

Do you "follow" Brane world collisions?

marcus

May27-04, 08:45 AM

I have not downloaded this----it is a long review paper on the physics of GRB: 159 pages. It probably could be mined for answers to questions about what causes GammaRay Bursts and what GRB events are actually like. the paper has been accepted by "Reviews of Modern Physics" so I would expect it to be suitably mainstream and authoritative.

http://arxiv.org/astro-ph/0405503
The Physics of Gamma-Ray Bursts
Tsvi Piran
159 pages, 33 figures, accepted for publication in Reviews of Modern Physics

marcus

May27-04, 08:52 PM

I was impressed by this short (11 page) paper by Daly and Djorgovski

http://arxiv.org/astro-ph/0405550
Direct Constraints on the Properties and Evolution of Dark Energy
Ruth A. Daly, S. G. Djorgovski
11 pages, 8 figures, invited presentation from the Observing Dark Energy NOAO Workshop in Tucson

It goes along with Wolram and other's interest in a skeptical appraisal of the dark energy idea.
D and D have developed a method to analyse the raw Supernova data with a minimum of assumptions----not assuming Friedmann equations or concordance model----and calculating the acceleration directly.

then they can say "what assumptions, what model, would get us this observed acceleration?"
in other words they proceed in a non-parametric way. they do not assume there are parameters like dark energy density and negative pressure, and try to find the value of these parameters. they assume nothing like that, they measure the acceleration--redshift relation and then try to find some mechanism that will fit it. then they bring in models, like concordance model, and try them out.

this is in a subtle way more difficult, but it is a commonsense approach,
it is scientifically respectable to work with as few assumptions as you possibly can (and still be able to process the data, get "traction" on the slippery road of the world in other words)

Ruth Daly has 22 papers in arxiv. many of them with Djorgovski.
this was an invited talk at a dark energy conference. She seems to me like
someone to listen to. Djorgovski is at CalTech. maybe Nereid knows of these people
*

marcus

May30-04, 07:45 PM

Here is a 66 page paper by Jonathan Feng
covering the interface between particle physics and cosmology
http://arxiv.org/hep-ph/0405215

"Supersymmetry and Cosmology"

In hep-ph, the ph stands for phenomenology, which studies the testing of theories by observation and measurement.

he describes the current situation where it is cosmology, with
its evidence for dark energy and dark matter----and it 4 percent estimate of the fraction that is baryon-matter. that is driving particle physics and astronomy that is offering prospects for testing various models.

he describes the interface between HEP and astrophysics/cosmology

astroparticle physics, particle astrophysics, whatever
different people call it different things.

he talks about the prospective role of accelerators too, how he thinks it all fits together.

it looks like an attempt at a review paper in a very new area, it is long, careful, with a lot of tables and/or graphs
he's a prominent expert. probably his viewpoint is worth understanding
it is a view of the nearterm future of physics, in some sense

Tom Mattson

May30-04, 07:54 PM

Straight from Physics Napster:

Astronomy and Cosmology

General:
Added 3/27/03
Publications of the Astronomical Society of Australia (http://www.atnf.csiro.au/pasa)
Added 3/28/03
Space Physics (http://spaceweb.oulu.fi) From Oulu, Finland.
Astronomy Dot Net (http://www.astronomy.net) The name says it all.

Cosmology:
Added 3/27/03
Cosmological Models (http://arxiv.org/abs/gr-qc/9812046) From LANL arXiv.

Astrophysics:
Added 3/27/03
Internal Dynamics of Globular Clusters (http://arxiv.org/abs/astro-ph/9610076) From LANL arXiv.

Simulators:
Added 3/27/03
Astronomy Software for PC (http://www.astronomy.ch/home.html)

and...

Relativity

Special Relativity:
Added 3/27/03
Lecture Notes on Special Relativity (http://www.lassp.cornell.edu/~cew2/P209/P209_home.html)
Added 3/28/03
On the Electrodynamics of Moving Bodies (http://www.fourmilab.ch/etexts/einstein/specrel/specrel.pdf) By Einstein, from Fourmilab.
Does the Inertia of a Body Depend on Its Energy Content? (http://www.fourmilab.ch/etexts/einstein/E_mc2/e_mc2.pdf) By Einstein, from Fourmilab.
Special Relativity (http://physics.nyu.edu/hogg/sr) by David Hogg—nice book.
Added 7/11/03
Special Relativity Questions (http://astsun.astro.virginia.edu/~jh8h/Foundations/quest7.html) Answered by Virginia's Astronomy Department.
Essay on the Twin Paradox (http://www.ccinet.ab.ca/tcantine/TP.html)

General Relativity:
Added 3/27/03
Lecture Notes on General Relativity (http://arxiv.org/abs/gr-qc/9712019) From LANL arXiv.
Added 3/28/03
Lecture Notes on General Relativity (http://pancake.uchicago.edu/~carroll/notes) by Prof. Sean Carroll, Univ. of Chicago.
Added 7/11/03
Sidelights on Relativity (http://www.focusresearch.com/texts/sor-latex.phtml) By Einstein.
Special and General Relativity E-Text (http://aci.mta.ca/Courses/Physics/4701_97/etext.html) From Mount Allison University (in progress).

Other:
Added 3/27/03
The Physical Basis of the Direction of Time (http://www.time-direction.de) This could have gone either in the Quantum or Relativity section. I flipped a coin, and here we are.
Added 3/28/03
Living Reviews in Relativity (http://www.livingreviews.org) An online journal.

marcus

Jun4-04, 02:57 PM

Stanford/SLAC puts out lists of topcited articles each year
the 2003 topcites are out
and there is a special review of the Astrophysics list
by Scott Dodelson

http://www.slac.stanford.edu/library/topcites/2003/eprints/astro-ph_review.shtml

marcus

Jun7-04, 07:11 PM

http://arxiv.org/abs/astro-ph/0406139
A Quantum Approach to Dark Matter
Authors: A. D. Ernest
Comments: To be published in "Progress in Dark Matter Research" Nova Science Inc. New York

"This work develops and explores a quantum-based theory which enables the nature and origin of cold dark matter (CDM) to be understood without need to introduce exotic particles. The quantum approach predicts the existence of certain macroscopic quantum structures that are WIMP-like even when occupied by traditional baryonic particles. These structures function as dark matter candidates for CDM theory on large scales where it has been most successful, and retain the potential to yield observationally compliant predictions on galactic cluster and sub-cluster scales. Relatively pure, high angular momentum, eigenstate solutions obtained from Schrodinger's equation in weak gravity form the structural basis. They have no classical analogue, and properties radically different from those of traditional localised matter (whose eigenstate spectra contain negligible quantities of such states). Salient features include radiative lifetimes that can exceed the age of the universe, energies and 'sizes' consistent with galactic halos, and negligible interaction rates with radiation and macroscopic galactic objects. This facilitates the formation of sparsely populated macroscopic quantum structures that are invisible and stable. Viable structure formation scenarios are based on the seed potential wells of primordial black holes formed at the e+/e- phase transition. The structures can potentially produce suitable internal density distributions and have capacity to accommodate the required amount of halo dark matter. The formation scenarios show that it is possible to incorporate structures into universal evolutionary scenarios without significantly compromising the results of WMAP or the measurements of elemental BBN ratios."

meteor

Jun27-04, 06:24 PM

Grzegorz Wardziñski offers all the abstracts of the latest papers in Astro-ph in Arxiv, all in the same page. The section is called Astro-ph for busy people. Wonderful!
http://www.camk.edu.pl/~gwar/astro-ph.html

marcus

Aug1-04, 12:15 PM

turbo points out that Aunt Nettie
has an explanation for why grass is green---
it is trying to get a message back to its home planet.
http://www.dearauntnettie.com/archives/archives-0105.htm
(dont believe this! it may be intended as a joke)

marcus

Aug13-04, 04:56 PM

Quantum Gravity Phenomenology

http://ws2004.ift.uni.wroc.pl/html.html

WS-2004 symposium, Feb 4-14
notes for all the talks are online, click on "lectures"
for a listing
a number of the talks are also on arxiv. search under author name.

marcus

Aug15-04, 12:14 PM

Chronos supplied this link
http://www.astrosociety.org/pubs/mercury/31_02/nothing.html
to a non-technical discussion by Filippenko and Pasachoff of
how the universe can have zero total energy
(positive mass-energy of matter balanced by negative gravitational potential)

marcus

Aug23-04, 01:10 PM

http://astsun.astro.virginia.edu/~jh8h/Foundations/Friedmann.html

sol put this curvegraphing applet link
which is good

but we somehow dont have a good post about the Friedmann eqns.
on this sticky thread and we should. I will try to get something

but please if anybody has a better discussion of the basic equations of cosmology, showing the Lambda which has become so important, please
post it

marcus

Aug23-04, 01:30 PM

in an earlier post on this thread we had a little bit about the Friedmann eqns. but this is better and also here is a link to a Sean Carroll piece in LivingReviews. the people at Albert Einstein Institute-Potsdam MPI asked Carroll to do the piece on "Cosmological Constant" for LivingReviews

http://relativity.livingreviews.org/Articles/lrr-2001-1/node3.html

Sean Carroll is a blogger as well as one of the worlds foremost cosmologists. he's at chicago. check out his blog sometime--it can be entertaining---the name is "preposterousuniverse"
------------------

In what follows I am using the same notation Sean Carroll uses in
LivingReviews which is pretty standard.

First here is a version of the Friedmann equations which conceals the cosmological constant as "dark energy" added into the rho term as another kind of energy density. So you dont see the Lambda explicitly in this version. This is how a lot of people do it nowadays, and the dark energy fraction is given as 73 percent of total energy density rho.

(\frac{a'}{a})^2 = \frac{8\pi G}{3}\rho - \frac{k}{a^2}

\frac{a''}{a}= -\frac{4\pi G}{3}(\rho + 3p)

Now I'm going to separate the cosmological constant part out as Lamda, an inverse distance squared term. Now rho is all the other stuff, not counting dark energy, and the equations are:

(\frac{a'}{a})^2 = \frac{8\pi G}{3}\rho - \frac{k}{a^2} + \frac{\Lambda}{3}

\frac{a''}{a}= -\frac{4\pi G}{3}(\rho + 3p)+\frac{\Lambda}{3}

EXPLAINING THE NOTATION
this is with c = 1 units, which simplifies things some.
the scale factor of the metric (whose increase is the expansion of the universe) is denoted by the letter a.
k is a spatial curvature parameter used to distinguish three cases
k = -1, 0, +1 for negative curvature, spatially flat, positive curvature

rho is an energy density, and easy to confuse with p pressure

the universe appears to be spatially flat, the critical density rhocrit is that needed for it to be perfectly flat with k = 0

HOW THE HUBBLE PARAMETER COMES IN
the Hubble parameter H is defined to be the time derivative a' of the scale parameter a, divided by a.
H^2 = (\frac{a'}{a})^2
for the time being assume we've included the Lambda term in rho as "dark energy, because this is a convenient way to set things up for calculating stuff, like the critical density. In the case of a spatially flat universe the first Friedmann equation boils down to

H^2 = \frac{8\pi G}{3}\rho_{crit}

algebraically that turns into the formula for the critical density

\rho_{crit} = \frac{3}{8\pi G}H^2

the Hubble parameter has been measured really accurately at 71 km/s per Mpc
and this lets us calculate the critical density at 0.83 joule per cubic km.since the U tests out flat or very nearly so, this is taken to be the
density of all the stuff, stars galaxies, light, dark matter, dust, dark energy etc. It all amounts to 0.83 joule per cubic km.

And the dark energy being 73 percent (from supernova data) means that its share is 0.6 joule per cubic km.

sol2

Aug23-04, 01:38 PM

sol put this curvegraphing applet link
which is good

but we somehow dont have a good post about the Friedmann eqns.
on this sticky thread and we should. I will try to get something

but please if anybody has a better discussion of the basic equations of cosmology, showing the Lambda which has become so important, please
post it

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/fried.html

This is a good link Marcus as well, and will lead you to many of the equations.

Marcus, part of this journey for me, was recognizng how the universe could move from our past, to our now, and if we could not look beyond to the hyper geometries, how could we have ever accepted any views in cosmology like Reimann's? :smile:

What comes next? Omega? :smile:

marcus

Sep2-04, 09:54 AM

Pete contributed this to the "Dark Energy" thread. this shows the cosm. const. Lambda in the context of the full GR equation.
I have usually been discussing this in the simplified context of the Friedmann equations, derived from the full Einstein equation. What Pete has taken the trouble to put in LaTex is a useful reference, so I'll just copy it here:
---exerpt from Pete---
The term Dark Energy is given to that matter which is causing the universe to expand at an accelerating rate. This is what some call "anti-gravity" since this is clearly gravity acting in a repulsive manner.
Back in Einstein's day nobody knew of any kind of matter which could produce such an effect. since Einstein assumed that the universe was static he added a term to his field equations to allow for this repulsive effect. Einstein's equations changed from

G^{\alpha\beta} = \frac{8\pi G}{c^4}T^{\alpha\beta}

to

G^{\alpha\beta} + \Lambda g^{\alpha\beta} = \frac{8\pi G}{c^4}T^{\alpha\beta}

\Lambda is called the cosmological constant. In modern terms the cosmological constant is also called "Dark Energy." This is the term which, for normal matter, allows for anti-gravity when \Lambda > 0....
---endquote---
for full post see
http://www.physicsforums.com/showthread.php?p=30180#post301180

some more links for good measure
http://math.ucr.edu/home/baez/gr/outline1.html
http://math.ucr.edu/home/baez/einstein/einstein.html

marcus

Sep5-04, 06:39 PM

Correction to previous post (too late to edit)
where one of the links was wrong

Ned Wright's balloon animation
http://www.astro.ucla.edu/~wright/balloon0.html
Cartoon strip about the particle horizon being 3X what you naively expect
http://www.astro.ucla.edu/~wright/photons_outrun.html
Microlensing by a star
http://www.astro.ucla.edu/~wright/microlensing.html
Cluster of galaxies lensing animation
http://www.astro.ucla.edu/~wright/cluster-lensing.html
Inflation animation
http://www.astro.ucla.edu/~wright/CMB-MN-03/inflating_bubble.html
Animation of what "Equal Power on All Scales" means---part of
understanding the fluctuations shown by the Microwave Background
http://www.astro.ucla.edu/~wright/CMB-MN-03/epas.html

turbo

Sep6-04, 03:12 PM

Here's a nice non-technical overview of the state of quantum gravity research, including some basic information about how studying cosmic rays and gamma ray bursts might help probe the structure of spacetime.

http://arxiv.org/abs/physics/0311037

marcus

Sep19-04, 07:57 PM

Here is an introductions to cosmology, in about 60 pages:

http://arxiv.org/abs/astro-ph/0409426

An overview of Cosmology
Authors: Julien Lesgourgues
Lecture notes for the Summer Students Programme of CERN (2002-2004). 62 pages, 30 figures.

Very basic conceptual introduction to Cosmology, aimed at undergraduate students with no previous knowledge of General Relativity

---abstract---
While purely philosophical in the early times, and still very speculative at the beginning of the twentieth century, Cosmology has gradually entered into the realm of experimental science over the past eighty years. It has raised some fascinating questions like: is the Universe static or expanding ? How old is it and what will be its future evolution ? Is it flat, open or closed ? Of what type of matter is it composed ? How did structures like galaxies form ? In this course, we will try to give an overview of these questions, and of the partial answers that can be given today. In the first chapter, we will introduce some fundamental concepts, in particular from General Relativity. In the second chapter, we will apply these concepts to the real Universe and deal with concrete results, observations, and testable predictions.
---end quote---

meteor

Oct9-04, 05:03 PM

Helioseismology: the study of the interior of the sun by observing the oscillations on its surface. This is a 60 pages paper that offers an introduction to the subject, also includes an historical review. All that you want to know about f-modes, g-modes, ring-diagram analysis, helioseismic holography,...can be found here. Title of the paper: "Helioseismology"
http://arxiv.org/abs/astro-ph/0207403

marcus

Oct25-04, 11:55 AM

Sean Carroll online Cosmology Primer

good FAQ
http://pancake.uchicago.edu/%7Ecarroll/cfcp/primer/faq.html

rest of Primer is probably very good also, but havent reviewed it yet.
see what you think

meyer_lev3

Oct28-04, 08:14 AM

marcus

Oct28-04, 10:21 AM

New member, first post :rofl:

Streaming video of lectures/talks on current topics by Hawking, Weinberg, others.

Especially good is "Brane New World" (2003) By Steven Hawking.

http://www.phys.cwru.edu/events/cerca_video_archive.php

Enjoy :wink:.

thanks for the link, meyer_lev, and welcome.
Personally, I wasn't aware of this Case Western Reserve archive of public lectures on cosmology topics. Impressive list of speakers and panelists.

turbo

Nov13-04, 03:28 PM

My apologies if this has been posted previously. It is a fascinating overview of Physics papers from the last 110 years or so. You can browse by field, author, decade, etc.

http://fangio.magnet.fsu.edu/~vlad/pr100/

turbo

Nov25-04, 09:21 AM

http://www.sundog.clara.co.uk/halo/halosim.htm

The graphics are not hot-linked, but they are well-labeled, and the menus at the left will link you to further information.

marcus

Dec1-04, 11:33 PM

Peter Dunsby's online course. special and general relativity
very basic for the most part
http://vishnu.mth.uct.ac.za/omei/gr/index.html

marcus

Jan17-05, 12:19 AM

Here is a link with some physical data about Titan
http://library.thinkquest.org/18188/english/planets/saturn/moons/titan.htm
I will try to get some other links, just to confirm the numbers.
they say

mass 1.35E23 kilogram (2.259 percent of earth)
radius 2575 km
density 1.88
distance from Saturn 1,221,850 km
orbital period 15.945 days
surface temperature -178 celsius
surface pressure 1.6 bar (60 percent more pressure than earth)
escape velocity 2.65 km/second

this data is before Huygens and some of it might have already been improved on.
If anybody knows some better please post it. TIA.

Possibly the most reliable source is a JPL site I just found:
http://ssd.jpl.nasa.gov/sat_props.html
http://ssd.jpl.nasa.gov/sat_elem.html

Here is a sample---BTW they dont show mass in kilograms, they show GM (which is what astronomers measure, and then infer mass from it)

Titan
GM (km3/sec2) 8978.0 ± 0.8
Radius (km) 2575.5 ± 2.
Density (g/cm3) 1.880 ± 0.004

this site was updated as recently as November 2004
just for comparison here's what JPL NASA has for 4 jovians

Io
5959.916 ± 0.012
1821.6 ± 0.5
3.528 ± 0.006

Europa
3202.739 ± 0.009
1560.8 ± 0.5
3.013 ± 0.005

Ganymede
9887.834 ± 0.017
2631.2 ± 1.7
1.942 ± 0.005

Callisto
7179.289 ± 0.013
2410.3 ± 1.5
1.834 ± 0.004

Here's the main address
http://ssd.jpl.nasa.gov/

marcus

Jan25-05, 07:35 PM

intriguing new technique for measuring the mass of a star
http://arxiv.org/abs/astro-ph/0501548

European Space Agency page of facts about Titan
http://www.esa.int/SPECIALS/Cassini-Huygens/SEMMF2HHZTD_0.html

wolram

Jan28-05, 11:54 AM

http://xyz.lanl.gov/pdf/gr-qc/0501041
The basics of gravitational wave theory
47 pages jan 2005
Please discard this if it is of no use.

Physik

Mar2-05, 05:35 PM

Orbital Mechanics Basics

This is a very cool site that explains Orbital Mechanics from the beginning, and explains all the math steps of the equations. (Unlike some other sites I've been to.)

http://www.braeunig.us/space/orbmech.htm

turbo

Mar2-05, 07:51 PM

I have been plowing through the Vega lectures (including the wonderful Feynman series) and linked resources, and found that this man has linked streaming videos from academic programs all over the world. If you enjoy science, I know what you'll be doing for the next few months. :devil:

http://web.mit.edu/people/cabi/Links/physics_seminar_videos.htm

marcus

Mar6-05, 01:18 PM

http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0009F0CA-C523-1213-852383414B7F0147

Popular written feature article "Misconceptions about BigBang"
Here are some sample "sidebars" of the article. Each has one or more visual diagrams with a wrong answer discussed and a right answer explained.

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p39.gif
What kind of explosion was the big bang?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p40.gif
Can galaxies recede faster than light?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p42.gif
Can we see galaxies receding faster than light?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p43.gif
Why is there a cosmic redshift?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p44.gif
How large is the observable universe?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p45.gif
Do objects inside the universe expand, too?

marcus

Mar25-05, 01:14 AM

a NASA resource for teachers called "ask a high energy astronomer"
http://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html

when I sampled it I found a lot dated in the late 1990s, which can be fine.
lot of it was good information. some things I came across seemed questionable or outdated. worth keeping tabs on though

like this nasa page has a link to a list of "known black holes"
which gives some details about each of the one listed
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/011120a.html

http://mintaka.sdsu.edu/faculty/orosz/web/

marcus

Mar27-05, 07:42 PM

I like Thanu Padmanabhan, he is a worldclass relativist and cosmologist and he uses references to lewis carroll hunting of the snark
and generally manages to be deep and witty some of the time
and he also pulled the rug out from under string theory recently with his paper that says it is not enough for a theory to produce gravitons, that does not make it a quantum gravity theory
he had this paper From Gravitons to Gravity: Myths versus Reality

Well padmanabhhan has come out with one of these surveys of cosmology for general audience, that a senior cosmologist may do every now and then.
http://arxiv.org/abs/gr-qc/0503107
Understanding Our Universe: Current Status and Open Issues
T. Padmanabhan
To appear in "100 Years of Relativity - Space-time Structure: Einstein and Beyond", A.Ashtekar (Editor), World Scientific (Singapore, 2005); 30 pages; 4 figures

"Last couple of decades have been the golden age for cosmology. High quality data confirmed the broad paradigm of standard cosmology but have thrusted upon us a preposterous composition for the universe which defies any simple explanation, thereby posing probably the greatest challenge theoretical physics has ever faced. Several aspects of these developments are critically reviewed, concentrating on conceptual issues and open questions. [Topics discussed include: Cosmological Paradigm, Growth of structures in the universe, Inflation and generation of initial perturbations, Temperature anisotropies of the CMBR, Dark energy, Cosmological Constant, Deeper issues in cosmology.]"

turbo

Apr3-05, 10:48 AM

WGBH forum with streaming video lectures on LOTS of subjects, including astronomy (under the science subject heading).

http://forum.wgbh.org/wgbh/

marcus

Apr3-05, 09:05 PM

http://arxiv.org/abs/physics/0503245
Neutron Stars
Gordon Baym, Frederick K. Lamb
Comments: Encyclopedia of Physics 3rd ed., R.G. Lerner and G.L. Trigg, eds., Wiley-VCH, Berlin

Abstract: "This short encyclopedia article, reviewing current information on neutron stars, is intended for a broad scientific audience."

Only 3 pages, but has a lot of interesting facts about the topic

Also turbo supplied a link to a Feynman lecture audio on conservation of energy

http://home.hockaday.org/HockadayNet/academic/physics/SciTeach/FeynEng.html

cosmoboy

Apr6-05, 04:17 AM

hi,
I woould like to suggest the following:

Review articles
1. Large scale structure of the universe and cosmological
perturbation theory (Bernardeau et al)
http://arxiv.org/abs/astro-ph/0112551
2. Cosmological Constant - the Weight of the Vacuum
( T. Padmanabhan)
http://arxiv.org/abs/hep-th/0212290
3. Lagrangian Perturbation and Other Approximations to Nolinear Gravitational Evolution
http://www.columbia.edu/~fms5/w161.html

Books
1.Particle Physics and Inflationary Cosmology
(Andrei Linde)
http://arxiv.org/abs/hep-th/0503203

marcus

Apr7-05, 07:29 PM

this paper describes a possible test of GR using LISA
Clifford Will is a co-author
http://arxiv.org/abs/gr-qc/0504017

marcus

May5-05, 10:33 PM

A FAQ is what does it mean that the old classical model of BH fails to compute at a certain point (has a "singularity") and gives non-physical answers or no answers at all.

What it means is a fault or limitation of the old classical Gen Rel theory. So now people are studying improved models of BH which dont have that failing. here are some people:

Abhay Ashtekar, Viqar Husain, Oliver Winkler, Leonardo Modesto, Martin Bojowald, Roy Maartens, Rituparno Goswami, Parampreet Singh.

Here are some recent research papers that they have written:

http://arxiv.org/abs/gr-qc/0504029
http://arxiv.org/abs/gr-qc/0503041
http://arxiv.org/abs/gr-qc/0504043
http://arxiv.org/abs/gr-qc/0411032
http://arxiv.org/abs/gr-qc/0407097
http://arxiv.org/abs/gr-qc/0412039
http://arxiv.org/abs/gr-qc/0410125

wolram

May24-05, 04:55 AM

http://www.psychcentral.com/psypsych/Milky_Way

The Milky-way lots of links and info on our backyard.

cosmo_boy

Jun29-05, 10:52 PM

Use this topic to post links to helpful/informative websites about astronomy & cosmology. [a)]

Here you can find many interesting recent papers in
physics & astrophysics.

http://web.mit.edu/redingtn/www/netadv/welcome.html

marcus

Sep23-05, 08:00 PM

http://chandra.harvard.edu/photo/2002/0192/BH_merge_sm.mov

This an animation of the collision and merger of two galaxies followed by the merger of their central supermassive black holes. the black holes spiral in towards each other ever faster as they loose energy by radiating away gravity waves.

Here is an update of something posted a few times back: a FAQ is what does it mean that the old classical model of BH fails to compute at a certain point (has a "singularity") and gives non-physical answers or no answers at all.

What it means is a fault or limitation of the old classical Gen Rel theory. So now people are studying improved models of BH which dont have that failing. here are some people:

Abhay Ashtekar, Viqar Husain, Oliver Winkler, Leonardo Modesto, Martin Bojowald, Roy Maartens, Rituparno Goswami, Parampreet Singh.

Here are some recent research papers that they have written:
http://www.arxiv.org/abs/gr-qc/0509075 (Ashtekar and Bojowald latest)
http://www.arxiv.org/abs/gr-qc/0509078 (Modesto latests)
http://arxiv.org/abs/gr-qc/0504029
http://arxiv.org/abs/gr-qc/0503041
http://arxiv.org/abs/gr-qc/0504043
http://arxiv.org/abs/gr-qc/0411032
http://arxiv.org/abs/gr-qc/0407097
http://arxiv.org/abs/gr-qc/0412039
http://arxiv.org/abs/gr-qc/0410125

marcus

Sep29-05, 11:50 AM

H. Rosewater has pointed out that this reference thread has no discussion of what it means to assume the universe is spatially homogeneous and isotropic.
Hellfire gave a pointer to this PF thread:
http://www.physicsforums.com/showthread.php?p=730619#post730619
where hellfire and SpaceTiger supply definitions and some examples are discussed.

I think these are symmetry assumptions-----one knows that the universe is spatially NOT symmetric but is instead fascinatingly different everywhere one looks, but that averaged out at large scale it has approximate symmetry. So for simplicity and convenience one decides to assume perfect translational and rotational symmetry.

That being decided, thereafter whatever functions one uses to describe the universe at some moment in time must have translational symmetry (be unchanged by shifting the origin) and rotational symmetry (be unchanged by rotating the coordinates)

Feel free to expand or clarify. If anyone comes up with a link to some particularly good definition please post it. otherwise, for more discussion see what hellfire and SpaceTiger had to say

marcus

Nov20-05, 09:23 PM

this might turn out to be a handy reference, it reviews why one usually accepts that things that look like black holes really are that---even though one wants to keep on testing and checking

http://arxiv.org/abs/hep-ph/0511217
Trust but verify: The case for astrophysical black holes
Scott A. Hughes
Based on invited lectures at the 2005 SLAC Summer Institute (SSI05-L006). 22 pages, 5 eps figures
"This article is based on a pair of lectures given at the 2005 SLAC Summer Institute. Our goal is to motivate why most physicists and astrophysicists accept the hypothesis that the most massive, compact objects seen in many astrophysical systems are described by the black hole solutions of general relativity. We describe the nature of the most important black hole solutions, the Schwarzschild and the Kerr solutions. We discuss gravitational collapse and stability in order to motivate why such objects are the most likely outcome of realistic astrophysical collapse processes. Finally, we discuss some of the observations which -- so far at least -- are totally consistent with this viewpoint, and describe planned tests and observations which have the potential to falsify the black hole hypothesis, or sharpen still further the consistency of data with theory."

marcus

May21-06, 06:39 PM

Cosmic neutrino background, why the temperature is less by a factor of 1.401

this is from the Georgia State University knowledge base called "hyperphysics" run by their physics and astronomy department
http://www.phy-astr.gsu.edu/new_web/newmain.html

http://hyperphysics.phy-astr.gsu.edu/Hbase/astro/neutemp.html

marcus

Oct10-06, 05:43 PM

Some ideas for future tests of General Relativity.
I was intrigued and wanted to keep tabs on this short (4 page) paper:

http://arxiv.org/abs/gr-qc/0610047
Testing General Relativity with Atom Interferometry
Authors: Savas Dimopoulos, Peter W. Graham, Jason M. Hogan, Mark A. Kasevich
4 pages, 1 figure

"The unprecedented precision of atom interferometry will soon lead to laboratory tests of general relativity to levels that will rival or exceed those reached by astrophysical observations. We propose such an experiment that will initially test the equivalence principle to 1 part in 10^15 (300 times better than the current limit), and 1 part in 10^17 in the future. It will also probe general relativistic effects--such as the non-linear three-graviton coupling, the gravity of an atom's kinetic energy, and the falling of light--to several decimals. Further, in contrast to astrophysical observations, laboratory tests can isolate these effects via their different functional dependence on experimental variables."

the authors are all at the Stanford physics department

Garth

Oct14-06, 12:06 AM

Astronuc

Mar24-07, 09:26 AM

NASA's Astrophysics Science Division Colloquium Series

http://www.universe.nasa.gov/seminars/EUDcolloq/

Astronuc

May21-07, 07:30 PM

This collection may be of interest -

Supernovae and Gamma Ray Bursts
June 21, 2004 - August 27, 2004
http://www.int.washington.edu/talks/WorkShops/int_04_2/

There are a lot more -

http://www.int.washington.edu/talk_list.html

http://www.int.washington.edu/PROGRAMS/programs_all.html

http://www.int.washington.edu/PROGRAMS/past_programs.html

Stellar Abundances & Nucleosynthesis Conference
http://www.int.washington.edu/talks/WorkShops/Stellar/

marcus

May26-07, 12:12 AM

Siobhan Morgan's redshift calculator has a new URL

http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html

when you start with it, put in three standard parameters
matter density 0.27
Lambda density 0.73
Hubble parameter 71

then it is ready and you can put some redshift like 3 into the "z box"
and it will give you data on light coming to us with that redshift
like travel time
and recession speed when and where the light was emitted
and recession speed of the emitter object now, etc.

Huashan

Jun18-07, 05:22 AM

This collection may be of interest -

Supernovae and Gamma Ray Bursts
June 21, 2004 - August 27, 2004
http://www.int.washington.edu/talks/WorkShops/int_04_2/

...

Wow ... great!!... i suggest everybody to see this ..:!!)

thanks ....

marcus

Jul17-07, 01:29 PM

Good talk given by Roger Penrose at Cambridge on 7 November 2005

http://www.newton.cam.ac.uk/webseminars/pg+ws/2005/gmr/gmrw04/1107/penrose/

topic was "Before the Big Bang"
and he said that only a couple of months earlier if someone had asked him he would have given the conventional answer that the question didn't make sense and there wasn't any "before"

if we can believe that, which could involve some striving for effect, then as recently as September 2005, Penrose would have said nothing before big bang, undefined.

but apparently now he has changed his mind----likes to talk about ideas of what was before the start of our universe expansion.
I heard him give the same talk in 2006, same slides, at MSRI Berkeley in 2006, and he also gave the talk at Perimeter in 2006.

great thing about this talk is his handdrawn pictures. good cartoonist. helps you understand both cosmology and thermodynamics in a more visual intuitive way
incredible what some people can do with just 3 or 4 different colors of felt-tip pen

Astronuc

Jul21-07, 07:13 AM

Look for the complete series 'UA: Space University' beginning this Sunday, July 29, both online and in the print edition of the Arizona Daily Star.

http://regulus2.azstarnet.com/mediaskins/main.php?id=1823

Series Preview - UA: Space University
Observers at the University of Arizona's Steward Observatory telescope on Mt. Lemmon search the sky for objects that could collide into Earth. First part is an interview with Stephen Larson.

Astronuc

Aug10-07, 06:40 AM

This might be of interest to students

ASTC22 Galactic and Extragalactic Astrophysics
http://planets.utsc.utoronto.ca/~pawel/ASTC22/

Astronuc

Aug19-07, 04:36 PM

Structure and dynamics of the solar chromosphere
Johannes Mattheus Krijger

http://igitur-archive.library.uu.nl/dissertations/2003-0321-121547/inhoud.htm

Astronuc

Aug28-07, 09:59 PM

Also referenced in some older papers as Carnegie Nearby Galaxy Survey

from http://arxiv.org/PS_cache/astro-ph/pdf/0508/0508338v1.pdf
[10] Mathewson D. S., Ford V. L., Buchhorn M., 1992, ApJS, 81, 413
[11] Persic M., Salucci P., 1995, ApJS, 99, 501

http://www.ociw.edu/%7Elho/projects/CINGS/CINGS.html

http://www.ociw.edu/~lho/projects/CINGS/Survey/index.html

http://www.ociw.edu/~lho/projects/CINGS/Survey/survey.html

Doesn't seem to have been updated in the last 2 years.

But it has photometric properties -
http://www.ociw.edu/~lho/projects/CINGS/Survey/leda2.html

Astronuc

Aug28-07, 10:07 PM

http://www.astronomy.ohio-state.edu/~survey/

The goal of the Ohio State Bright Spiral Galaxy Survey is to create a database of deep, photometrically calibrated images of a complete magnitude limited sample of nearly 200 bright, nearby, well-resolved spirals.

Near-IR and Optical Morphology of Spiral Galaxies
http://www.arxiv.org/abs/astro-ph/0206320/

Galaxies from the OSU Spiral Galaxy Survey Master List for which
BVRJHK observations have been completed.
http://www.astronomy.ohio-state.edu/~frogel/OSUgalsurvey/GalaxiesDone.html

http://www.astronomy.ohio-state.edu/~survey/EDR/Data/

Astronuc

Oct12-07, 07:41 PM

report on the detection of X-ray emission from the unusual Galactic radio source G357.7-0.1 (the "Tornado"). Observations made with the Chandra X-Ray Observatory demonstrate the presence of up to three sources of X-ray emission from the Tornado:
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJL/v594n1/17398/17398.html?erFrom=-2587168887994415514Guest

Astronuc

Nov30-07, 04:31 AM

This might be of interest to those involved or seeking opportunities in visual/optical astronomy.

http://www.vlti.org/home.php

http://www.vlti.org/project.php?cid=2
Project Overview
ONTHEFRINGE is a series of four schools designed to train young astronomers in optical interferometry. Optical interferometry is a new technology enabling observations with angular resolution an order of magnitude larger than the largest single telescopes available at visible and infrared wavelengths. Optical interferometry is the only technology allowing the systematic direct detection and characterization of Earthlike planets orbiting other stars. Therefore it plays a key role in ESAs long-range plan through the Darwin mission, and in NASA's Origins program via TPF-I. On the ground Europe has achieved leadership with the ESO Very Large Telescope Interferometer (VLTI). Interferometry from the ground will play a central role in:

understanding the lifecycles of stars in the Milky Way,
the discovery and characterization of planets orbiting stars in the solar neighborhood, and
the understanding of the energy conversion mechanisms in Active Galactic Nuclei.

marcus

Dec20-07, 04:09 PM

Wallace found this link to the 2005 Lineweaver Davis article in the SciAm called
Misconceptions about the Big Bang.
http://www.astro.princeton.edu/~aes/AST105/Readings/misconceptionsBigBang.pdf

The article used to be available at the SciAm website but I've noticed that what they have there has been dwindling----some very educational graphics have been eliminated---maybe because storage is scarce.

It is a really good article, very helpful. Classic example of general audience hype-free science writing----cool clearheaded no gee-whiz---by a top expert. Much needed because of persistent misunderstanding of the standard world model

The collection that the link came from is worth knowing about
http://www.astro.princeton.edu/~aes/AST105/syllabus.notes.html

this gives the readings for a Princeton general astronomy course (for nonscience majors) no calculus needed.
the course was taught in 2005 by Ostriker and Shapley.
it is a good kind of course that can teach a lot about how we understand and measure the universe just using pictures, highschool mathematics like simple algebra and trig, and intuitive verbal description

there are a lot of links to readings here that could be useful to us at PF, as long as they stay live.
information page for the course (Astro 105) is
http://www.astro.princeton.edu/~aes/AST105/course.information.html
which has a link to the homepage at the bottom, if you want

marcus

Jan2-08, 04:03 PM

To have this handy to refer to,
http://arxiv.org/abs/astro-ph/0603449
Page 50 Figure 17
==quote==
Fig. 17.— Constraints on a non-flat universe with quintessence-like dark energy
with constant w (ModelM10 in Table 3). The contours show the 2-d marginalized
contours for w and Omega_k based on the the CMB+2dFGRS+SDSS+supernova data
sets. This figure shows that with the full combination of data sets, there are
already strong limits on w without the need to assume a flat universe prior.
The marginalized best fit values for the equation of state and curvature are
w = −1.08 ± 0.12 and
Omega_k = −0.026+0.016/−0.015 at the 68% confidence level.
==endquote==

The confidence interval for Omega_k is [-0.041, -0.010]

That means that the confidence interval for Omega_total, or simply Omega, is
[1.010, 1.041]

marcus

Feb14-08, 10:56 PM

Updating some basic cosmology links and getting a bunch of them together:

Ned Wright's cosmology tutorial
http://www.astro.ucla.edu/~wright/cosmolog.htm

Ned Wright's cosmology FAQ
http://www.astro.ucla.edu/~wright/cosmology_faq.html

Ned Wright's most basic cosmology calculator
http://www.astro.ucla.edu/~wright/CosmoCalc.html
(he has links to some more advanced or specialized calculators)

Morgan's calculator
http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html

Murphy's coordinate conversion tool
http://fuse.pha.jhu.edu/support/tools/eqtogal.html

Lineweaver and Davis' Scientific American article Misconceptions about the big bang March 2005.
AS LONG AS THIS PRINCETON LINK WORKS IT IS BETTER THAN THE OTHERS

http://www.astro.princeton.edu/~aes/AST105/Readings/misconceptionsBigBang.pdf

Here are the links to the same article at the SciAm website. But these links have been going dead or else the GRAPHICS that you used to get have been disappearing. So these SciAm links may not be as good as the Princeton one

http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0009F0CA-C523-1213-852383414B7F0147

The Lineweaver Davis article had some very useful SIDEBARS giving pictorial diagrams with a question together with right and wrong answers explained. For easier access, here are links to individual sidebars.

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p39.gif
What kind of explosion was the big bang?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p40.gif
Can galaxies recede faster than light?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p42.gif
Can we see galaxies receding faster than light?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p43.gif
Why is there a cosmic redshift?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p44.gif
How large is the observable universe?

http://www.sciam.com/media/inline/0009F0CA-C523-1213-852383414B7F0147_p45.gif
Do objects inside the universe expand, too?

Astronuc

Mar29-08, 07:54 PM

marcus has posted some links to relativity.livingreviews.com, and I stumbled on a set of articles about solarphysics.

http://solarphysics.livingreviews.org/Articles/index.html

Astronuc

Jun7-08, 06:35 AM

I found a nice little pocket handbook/guide for visual astronomers. I was discounted to $5 (normally $15) at Barnes & Noble.

Neil Bone (Illustrated by Wil Tirion), Deep Sky Observer's Guide, Firefly Books.

Astronuc

Jun7-08, 09:41 AM

Connecting Quarks with the Cosmos:
Eleven Science Questions for the New Century

http://www.nap.edu/catalog.php?record_id=10079

Advances made by physicists in understanding matter, space, and time and by astronomers in understanding the universe as a whole have closely intertwined the question being asked about the universe at its two extremes the very large and the very small. This report identifies 11 key questions that have a good chance to be answered in the next decade. It urges that a new research strategy be created that brings to bear the techniques of both astronomy and sub-atomic physics in a cross-disciplinary way to address these questions. The report presents seven recommendations to facilitate the necessary research and development coordination. These recommendations identify key priorities for future scientific projects critical for realizing these scientific opportunities.

marcus

Feb15-09, 02:07 PM

Fascinating article mentioned by Xantox:
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1995ApJ...446...63H&data_type=PDF_H IGH&whole_paper=YES&type=PRINTER&filetype=.pdf
Edward R. Harrison
Mining Energy in an Expanding Universe
This seems not to be available at the arxiv, but is from Harvard.

marcus

Mar21-09, 02:13 AM

Some Einstein quotes:
http://www.physicsforums.com/showthread.php?p=1386960#post1386960

“Dadurch verlieren Zeit & Raum den letzter Rest von physikalischer Realität. ..."

“Thereby time and space lose the last vestige of physical reality”.

(Possible paraphrase: space does not have physical existence, but is more like a bunch of relationships between events)

In case anyone wants an online source, see page 43 of this pdf at a University of Minnesota website
www.tc.umn.edu/~janss011/pdf%20files/Besso-memo.pdf

==quote from the source material==
...In the introduction of the paper on the perihelion motion presented on 18 November 1915, Einstein wrote about the assumption of general covariance “by which time and space are robbed of the last trace of objective reality” (“durch welche Zeit und Raum der letzten Spur objektiver Realität beraubt werden,” Einstein 1915b, 831). In a letter to Schlick, he again wrote about general covariance that
“thereby time and space lose the last vestige of physical reality” (“Dadurch verlieren Zeit & Raum den letzter Rest von physikalischer Realität.” Einstein to Moritz Schlick, 14 December 1915 [CPAE 8, Doc. 165]).
==endquote==

Both quotes are from Nov-Dec 1915, one being from a paper on perihelion motion. and the other from a letter to Moritz Schlick a few weeks later.

marcus

Mar25-09, 11:09 AM

Thanks to George Jones for this link:
http://arxiv.org/abs/gr-qc/0508052
"In an expanding universe, what doesn't expand?"
May be helpful in addressing a questions that often comes up in cosmo forum.

marcus

Mar30-09, 04:12 PM

R. Brent Tully (of the Tully Fisher relation) has some fine outreach material,
http://www.ifa.hawaii.edu/~tully/outreach/vv1a_9-25.mpg
See this animation of a trip up out of Milky's disk and then to the Virgo Cluster, eyeballing lots of stuff along the way and ending up in a giant elliptical.

See also this, which I had trouble streaming and couldn't evaluate but which might be interesting
http://www.ifa.hawaii.edu/~tully/pecv_12min_sound_qt.mov

I should alert readers to the fact that I have just become aware of Tully's website and outreach material. Although I am impressed by by the quality and by his reputation, I cannot say anything overall. He may have some unorthodox views. From my point of view this is how science happens. Individuals should have some individualistic views and not just follow the consensus. So this would be OK. But proceed with caution. I'm just now watching the sound movie and finding it very interesting although the streaming is spasmodic.

marcus

Jun1-09, 03:06 PM

Nobelist George Smoot talking about the CMB and what things it tells us.
Very skillful presentation with animated graphs, shows what bumps in the power spectrum mean, and why. Part of the "Honeywell Nobel" lecture series.

http://www.revver.com/video/827006/the-history-and-fate-of-the-universe-part-1-of-9/

http://www.revver.com/video/827106/the-history-and-fate-of-the-universe-part-2-of-9/

http://www.revver.com/video/827171/the-history-and-fate-of-the-universe-part-3-of-9/

http://www.revver.com/video/832550/the-history-and-fate-of-the-universe-part-4-of-9/

http://www.revver.com/video/832599/the-history-and-fate-of-the-universe-part-5-of-9/

http://www.revver.com/video/832643/the-history-and-fate-of-the-universe-part-6-of-9/

http://www.revver.com/video/832679/the-history-and-fate-of-the-universe-part-7-of-9/

http://www.revver.com/video/832724/the-history-and-fate-of-the-universe-part-8-of-9/

http://www.revver.com/video/832788/the-history-and-fate-of-the-universe-part-9-of-9/

marcus

Jun11-09, 08:19 PM

Primer on black holes.
For nonspecialist general audience by the president of the Royal Astronomical Society.
How we observe the black holes at the center of normal galaxies and quasar galaxies.
How they generate different kinds of radiation. Models. Inference.

Color illustrated magazine article somewhat on the level of SciAm, maybe a bit more math, but still fairly accessible.
http://arxiv.org/abs/0906.2119
Black Holes at Work
Andrew Fabian
published in Astronomy and Geophysics

marcus

Dec15-09, 07:58 PM

http://arxiv.org/pdf/0912.2809v1
Black Holes in an Expanding Universe
Gary W. Gibbons, Kei-ichi Maeda
4 pages, 1 table, 2 figures
(Submitted on 15 Dec 2009)
"An exact solution representing black holes in an expanding universe is found. The black holes are maximally charged and the universe is expanding with arbitrary equation of state. It is an exact solution of the Einstein-scalar-Maxwell system, in which we have two Maxwell-type U(1) fields coupled to the scalar field. The potential of the scalar field is an exponential. We find a regular horizon, which depends on one parameter (the ratio of the energy density of U(1) fields to that of the scalar field). The horizon is static because of the balance on the horizon between gravitational attractive force and U(1) repulsive force acting on the scalar field. We also calculate the black hole temperature."

This short article could be useful as a review with references to a number of earlier papers on models of black hole in expanding universe.

marcus

Mar12-10, 10:05 PM

Meteor posted this back in April 2004, almost 6 years ago. Time flies!
This paper seems interesting:
"Distance measures in cosmology"
David W. Hogg
http://arxiv.org/abs/astro-ph/?9905116

It must be good given that I really enjoyed the pdf course of special relativity of D. Hogg

Thanks to meteor for adding this to our A&C reference library. Hogg's tutorial is an excellent clear layout of the different distance measures. I recall finding it a real help at one time.
http://arxiv.org/abs/astro-ph/9905116

Of course Ned Wright's tutorial, and his cosmo calculator, should be mentioned as well.

If you don't know about this already, several different distance measures are used in astronomy. It's good to be reminded of this and of these resources. Thanks to Sylas for doing so most recently!

marcus

Mar14-10, 03:09 PM

http://arxiv.org/pdf/0909.3983
Latest estimates about the Cosmic Event Horizon (CEH) by Egan Lineweaver.
Current distance to it ~15.7 Gly (proper i.e. freezeframe distance)
what that is converging to ~16.4 Gly (likewise proper, or freezeframe distance).

Note the CEH is not the same as the Hubble distance ~13.7 Gly.

You can picture the proper distance (at a given moment) as what you would measure if you could freezde the expansion process at that moment and use conventional radar ranging or timing of lightsignals to measure in the usual way. The Hubble law v = Hd is based on this concept of distance.

The CEH is basically the distance to a galaxy which, if you left here today and traveled at the speed of light, you could never quite get to. Something closer than CEH you could, in principle, reach. It's definition depends on the standard cosmo model.

Astronuc

Apr9-10, 06:59 PM

Closer to home.

Nearest Star: The Surprising Science of Our Sun
Leon Golub, Jay M. Pasachoff

Leon Golub is an astrophysicist at the Harvard-Smithsonian Center for Astrophysics and is the head of one of the teams working with NASA's Transition Region and Coronal Explorer (TRACE) spacecraft.

Jay M. Pasachoff is Field Memorial Professor of Astronomy at Williams College and, having viewed 31 solar eclipses, is Chair of the Working Group on Eclipses of the International Astronomical Union.

Abstract: Unlike the myriad points of light we gaze at in the night sky, our nearest star allows us to study the wonders of stellar workings at blindingly close range--from a mere 93 million miles away. And what do we see? In this book, two of the world's leading solar scientists unfold all that history and science--from the first cursory observations to the measurements obtained by the latest state-of-the-art instruments on the ground and in space--have revealed about the Sun. Following the path of science from the very center of this 380,000,000,000,000,000,000-megawatt furnace to its explosive surface, Nearest Star invites readers into an open-ended narrative of discovery about what we know about the Sun and how we have learned it.

How did the Sun evolve, and what will it become? What is the origin of its light and heat? How does solar activity affect the atmospheric conditions that make life on earth possible? These are the questions at the heart of solar physics, and at the center of this book. Having made optical solar observations with many solar telescopes and in the rockets and satellites, the authors bring their extensive personal experience to this story of how astronomers study the Sun, and what they have discovered about phenomena from eclipses to neutrinos, space weather, and global warming. Richly illustrated with an assortment of pictures from the latest solar missions and the newest telescopes, this book is a very readable, up-to-date account of science's encounter with our nearest star.

http://www.hup.harvard.edu/catalog/GOLNEA.html (on sale ~$18)

Nearest Star (http://books.google.com/books?id=lRvIdqj3y8UC&dq=Nearest+Star+The+Surprising+Science+of+Our+Sun&printsec=frontcover&source=bn&hl=en&ei=3r2_S9aCM4P88Aa14sjxCA&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBcQ6AEwAw#v=onepage&q&f=false)

Astronuc

Dec8-10, 06:52 PM

OPPORTUNITIES IN NUCLEAR ASTROPHYSICS
Conclusions of a Town Meeting held at the University of Notre Dame
7-8 June 1999
http://www.nscl.msu.edu/~austin/nuclear-astrophysics.pdf

It would be interesting to do an update of this program.

Also - http://en.wikipedia.org/wiki/Joint_Institute_for_Nuclear_Astrophysics
http://www.jinaweb.org/

marcus

Dec12-10, 12:34 PM

New textbooks about the early universe. Expensive but the department library might be willing to order copies.

http://www.worldscibooks.com/physics/7874.html
INTRODUCTION TO THE THEORY OF THE EARLY UNIVERSE
Hot Big Bang Theory
by Dmitry S Gorbunov (Russian Academy of Sciences, Russia) & Valery A Rubakov (Russian Academy of Sciences, Russia & Moscow State University, Russia)
This book is written from the viewpoint of a deep connection between cosmology and particle physics. It presents the results and ideas on both the homogeneous and isotropic Universe at the hot stage of its evolution and in later stages. The main chapters describe in a systematic and pedagogical way established facts and concepts on the early and the present Universe. The comprehensive treatment, hence, serves as a modern introduction to this rapidly developing field of science. To help in reading the chapters without having to constantly consult other texts, essential materials from General Relativity and the theory of elementary particles are collected in the appendices. Various hypotheses dealing with unsolved problems of cosmology, and often alternative to each other, are discussed at a more advanced level. These concern dark matter, dark energy, matter-antimatter asymmetry, etc.
Contents:
Cosmology: A Preview
Homogeneous Isotropic Universe
Dynamics of Cosmological Expansion
ΛCDM: Cosmological Model with Dark Matter and Dark Energy
Thermodynamics in Expanding Universe
Recombination
Relic Neutrinos
Big Bang Nucleosynthesis
Dark Matter
Phase Transitions in the Early Universe
Generation of Baryon Asymmetry
Topological Defects and Solitons in the Universe

Readership: Cosmologists, advanced undergraduate and graduate students.
500pp (approx.)

http://www.worldscibooks.com/physics/7873.html
INTRODUCTION TO THE THEORY OF THE EARLY UNIVERSE
Cosmological Perturbations and Inflationary Theory
by Dmitry S Gorbunov (Russian Academy of Sciences, Russia) & Valery A Rubakov (Russian Academy of Sciences, Russia & Moscow State University, Russia)
This book accompanies another book by the same authors, Introduction to the Theory of the Early Universe: Hot Big Bang Theory and presents the theory of the evolution of density perturbations and relic gravity waves, theory of cosmological inflation and post-inflationary reheating. Written in a pedagogical style, the main chapters give a detailed account of the established theory, with derivation of formulas. Being self-contained, it is a useful textbook for advanced undergraduate students and graduate students. Essential materials from General Relativity, theory of Gaussian random fields and quantum field theory are collected in the appendices. The more advanced topics are approached similarly in a pedagogical way. These parts may serve as a detailed introduction to current research.
Contents:
Jeans Instability in Newtonian Gravity
Cosmological Perturbations in General Relativity. Equations of Linearized Theory
Evolution of Vector and Tensor Perturbations
Scalar Perturbations: Single-Component Fluids
Primordial Perturbations in Real Universe
Scalar Perturbations Before Recombination
Structure Formation
Beyond Ideal Fluid Approximation
Temperature of Cosmic Microwave Background Radiation
CMB Polarization
Drawbacks of the Hot Big Bang Theory. Inflation as Possible Way Out
Inflation in Slow Roll Regime
Generation of Cosmological Perturbations at Inflation
Further Aspects of Inflationary Theory
Preheating After Inflation
Bouncing Universe

Readership: Cosmologists, advanced undergraduate and graduate students.
480pp (approx.)

http://www.worldscibooks.com/physics/7235.html
PRIMORDIAL COSMOLOGY
by Giovanni Montani (ENEA & ICRANet, University of Rome “Sapienza”, Italy), Marco Valerio Battisti (ICRA & University of Rome “Sapienza”, Italy), Riccardo Benini (ICRA & University of Rome “Sapienza”, Italy), & Giovanni Imponente (Queen Mary, University of London, UK)
Primordial Cosmology deals with one of the most puzzling and fascinating topics debated in modern physics — the nature of the Big Bang singularity. The authors provide a self-consistent and complete treatment of the very early Universe dynamics, passing through a concise discussion of the Standard Cosmological Model, a precise characterization of the role played by the theory of inflation, up to a detailed analysis of the anisotropic and inhomogeneous cosmological models...
This book traces clearly the backward temporal evolution of the Universe, starting with the Robertson–Walker geometry and ending with the recent results of loop quantum cosmology in view of the Big Bounce. The reader is accompanied in this journey by an initial technical presentation which, thanks to the fundamental tools given earlier in the book, never seems heavy or obscure.
Contents:
Historical Picture — From Ancient Cultures to the 20th Century
Fundamental Tools — Einstein Theory and Singularity Theorems
The Structure and Dynamics of the Isotropic Universe
Shortcomings of the Standard Model and Inflationary Theory
Inhomogeneous Quasi-Isotropic Cosmology
Homogeneous Universes — Chaotic Cosmology
Hamiltonian Formulation of the Mixmaster — The Liouville Measure
The Generic Cosmological Solution — Singularity without Symmetries
Quantum Cosmology — From the Wheeler-DeWitt Approach to Loop Quantum Cosmology

Readership: Researchers in cosmology, high energy physics and quantum physics.
616pp (approx.)

Amazon links for these and related textbooks:
http://www.amazon.com/Introduction-Theory-Early-Universe-Bang/dp/9814322245/
http://www.amazon.com/Introduction-Theory-Early-Universe-Perturbations/dp/9814322229
http://www.amazon.com/Primordial-Cosmology-Giovanni-Montani/dp/9814271004/
http://www.amazon.com/Canonical-Gravity-Applications-Cosmology-Quantum/dp/0521195756/