Astronomy and Cosmology

There is a short animated film of the formation of a dwarf galaxy, based on supercomputer simulation. http://www.sciencenews.org/view/generic/id/54015/title/Supernova_winds_blow_galaxies_into_shape In the video you see occasional supernovae exploding, each time blowing away part of the ordinary matter that is trying to gather together. Time is speeded up and the video gradually zooms out, as the small protogalaxy blobs collide, coalesce, as the galaxy grows, and as its spiral structure develops. Finally the galaxy grows massive enough so that its own supernovae do not disrupt it. The animation is part of a proposed solution to a long-standing puzzle about s…

In the first paragraph below, the description's indicative of less heat (coldness of a void). Yet in the second and third paragraphs, the description's more indicative of a rise in heat. But isn't each a description of the same place, thus contradictory? http://en.wikipedia.org/wiki/Intergalactic_medium#Intergalactic Generally free of dust and debris, intergalactic space is very close to a total vacuum. Certainly, the space between galaxy clusters, called the voids, is nearly empty. Some theories put the average density of the universe as the equivalent of one hydrogen atom per cubic meter.[22][23] The density of the universe, however, is clearly not uniform; it …

On the BBC's Science page "Herschel space telescope captures birth of stars" which can be found at http://news.bbc.co.uk/1/hi/sci/tech/8416263.stm Palab Gosh (BBC Radio Science) who has a science degree from Imperial College narrates a short video where he states that stardust is seen "forming into clumps along magnetic lines". He goes on to talk about "magnetic eddys" when describing how the dust forms a new star. Please correct me if I'm wrong, but I always thought it was gravity that did the "clumping"!

The Cold Dark Matter theory, found here, has been used to explain how the universe formed into a cosmic array of galaxies from the moment of the big bang. This is from the above link: "In the cold dark matter theory, structure grows hierarchically, with small objects collapsing first and merging in a continuous hierarchy to form more and more massive objects. In the hot dark matter paradigm, popular in the early eighties, structure does not form hierarchically (bottom-up), but rather forms by fragmentation (top-down), with the largest superclusters forming first in flat pancake-like sheets and subsequently fragmenting into smaller pieces like our galaxy the Milky …

Apparently, during a Martian winter, sand particles can get stuck together and frozen carbon dioxide will cover them making a sort of "forest" from these structures. http://www.bild.de/BILD/news/2010/01/13/nasa-fotografiert/doch-sind-das-wirklich-baeume-auf-dem-mars.html

Chuck Lineweaver and his student Tammy Davis did everybody a big service by publishing a SciAm article covering the most common popular misconceptions about Expansion Cosmology (misnamed "Big Bang" Cosmology by someone who didn't like it.) the article is used for the Princeton basic course, so it is online at the Princeton.edu site, and also in a slightly tattered version it is still online at the SciAm site. To avoid making the worst fallacies, and wasting everyone's time, please please pretty please everybody who wants to discuss Cosmology make sure they either have read the article or already avoid making these very common naive mistakes. If somebody keeps …

I was just thinking, the LHC is supposedly going to kill us all right? Maybe the Norway Spiral has something to do with the LHC making it's first collisions? They are in the same general area and the dates sort of fit together. I have a hard time believing it is just a rocket that created such a beautiful but mysterious object.

It is stated in most scientific texts that what ever goes into a black hole never comes back out. I was wondering if this is absolutely true. Is it not possible that it just takes a very long time and then suddenly all of the mass that has been "gobbled up" by the black hole will suddenly be ejected? Are there any known instances in the universe of areas of space that spew mass? If so, could these be former black holes?

I never really liked the notion of the universe expanding, it leads to so many misconceptions. Think 4-d and think about space-time cuts into space and time. The ideas of expanding and what it expands into just go away. Relativity 1.01 think 4 dimensionally! The analogy I like is the cone. Lets cut out the conical singularity. Then globally the cone looks like a circle times an interval (part of the line). Orientate it so that the smaller circle is facing down. Now do some space-time cuts, that is cut up the cone into a series of circles. You see that they are all of different sizes. Now for the analogy. Imagine that the cone represents space - the circles an…

Read it all here: http://www.universetoday.com/2009/11/30/the-next-generation-of-heat-shield-magnetic/ This heat shield idea does make a lot of sense. When a craft enters the atmosphere, it generates heat from the immense pressure of reentry. When this happens much of that super-heated air becomes plasma and is able to be influenced by magnetic fields. Did I describe this accurately enough? Also, in the diagram on that site, the magnetic coil looks like a simple solenoid. Was this coil shape simplified for the causal reader, or is this the actual coil design? Or is it's because the coil is a superconductor it will provide a diamagnetic field? Merged post fo…

Hi, I would love to join your discussion forum, cosmology is never far from my mind, and I love to theorize about the Universe and all that. Another interest of mine is amateur fusion, I have a small lab where I can carry out small high voltage/vacuum experiments. I often like to bring up new ideas and hypothethise about new theories, I hope you guys are open to that. (not like those "standard model Nazi's" at the PhysicsForum ) Let logic and reason prevail Steven

According to mainstream science, the entire universe is generally agreed to be "flat". Just how do we know that it is flat? How does the data from COBE allow cosmologists to conclude that it is flat and not, say, donut shaped?

Fig. 21.16, on page 893, of Carroll & Ostlie's Intro. to Mod. Astrophys. [1st ed.], shows that (1) for stars more massive than [math]2 M_{\odot}[/math] (A5), Specific Angular Momentum (L/M) increases as M2/3; and, that (2) for stars less massive than said same value, the star's S.A.M. increases as M5 (with the deficit probably borne by planets, according to the caption). We seek an order-of-magnitude calculation, which can indicate some sort of suggestion, as to the origin of this [math]2 M_{\odot}[/math] threshold. S.A.M. for massive stars Please ponder an idealized Giant Molecular Cloud core, of constant density, from which a spherical fragment begins…

Dos vidanya, Apophis! http://ph.news.yahoo.com/ap/20091230/twl-eu-russia-asteroid-encounter-c8e2916.html

T Pyxidis, estimated 3000 lightyears from us, is being presented in science media as a potential supernova. I'm not sure this is right, or that it will be confirmed. But I respect Steinn Sigurdsson. He's a reputable astrophysicist. In my opinion reliable and hardhead, not a speculator. Judge for yourself from his other blog posting. Here's what he says about the T Pyxidis news: http://scienceblogs.com/catdynamics/2010/01/has_a_supernova_type_ia_progen.php The reports come from a group at Villanova University led by Prof. Edward Sion. What I get from this is that T Pyxidis is extremely interesting but most likely far enough away not to pose a threat to Earth, alt…

http://backreaction.blogspot.com/2009/06/shrinking-betelgeuse.html Giant stars have a short lifetime. Consume their fusible elements rapidly. When there is nothing more to fuse, they start cooling and shrinking, then collapse and blow. Interesting to study the shoulder star Betelgeuse (alpha Orionis) with that possibility in mind. It is close enough that instruments can actually resolve it and can measure the diameter by a couple of different methods. Diameter measurements by different teams over the course of fifteen years or so show a downtrend. This could be part of a cycle--and destined to reverse itself. Or it might continue shrinking. At the mom…

http://audio.wnyc.org/radiolab_podcast/radiolab_podcast081208.mp3 According to Mr. Green our universe is a quantum flux in the the inflaton field... and that section of the field gave up its energy to kickoff our universe. Could the expansion of the universe be thought of as an injection of entropy into our universe to dilute the energy enough to allow it to fall back to ZERO charge? so it may just dissolve to nothing some day? no hope of anything left behind. I know i am very layman i know... just trying to understand.

http://planetquest.jpl.nasa.gov/atlas/atlas_search.cfm?&Sort=DiscDate&SortDir=DESC FYI, five new exoplanets were posted today, for a total of 19 so far this year.

Spirit is apparently stuck in a sandy bit of Martian soil: http://marsrovers.jpl.nasa.gov/newsroom/pressreleases/20091231a.html Dust may continue to accumulate on its solar panel while it is stuck, until it no longer functions.

http://www.boston.com/bigpicture/2009/11/martian_landscapes.html?amazing All these Mars landscape shots are incredible and astonishingly beautiful. Some are taken from over the polar icecaps Apologies if somebody already posted link to these.

As the earth spins, lines of force facing the sun are 'compressed', and 'expanded' at the umbra. http://www.biocrawler.com/w/images/1/19/Magnetosphere_simple.jpg Does it mean they are constantly changing its position and shape as they pass from a compressed state at noon, to dusk, to midnight, to dawn ? Do they cyclically deform and also rotate ? Question number two... Electrical wiring in orbiting satellites are constantly crossing magnetic lines from the earth field. Does such generates 'stray' currents in their circuitry ?

Does space go on forever, or does space end? There is a "big" difference, if any way you go space goes on forever or if any way you go space ends. What is a "big" difference between those two ideas? If space goes on forever any way you go, space does not have a shape. If space ends any way you go, then space can take a shape. Space can take a shape, if space ends. There is another "big" difference whether space ends or not. Can you think of what that is?

See those letters in the sun glare? I have two questions: 1) where does it come from and 2) what does it say? It's probably the mirror image of a label somewhere on the camera. Upside down, it says "!R" or "IR" Assuming all letters are capital, the letter before the I is probably an N, the one behind the R probably an U — IRU.

“There are several ways in which a planet can disturb the internal motions of matter in its host star, thereby rearrange the distribution of the various chemical elements and possibly cause the destruction of lithium. It is now up to the theoreticians to figure out which one is the most likely to happen,” http://www.eso.org/public/outreach/press-rel/pr-2009/pr-42-09.html FYI, a lack of lithium in a star may indicate the presence of exoplanets. This could be a short cut for exoplanet hunters.

Evidence !!! Show me all the Evidence !!! , that space goes on forever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ev…