Astronomy and Cosmology

The paper may be downloaded at the following link: http://fr.calameo.com/books/000145333477ac4808aec SUMMARY: The principal objective of this study was to investigate the formation and evolution of quasars. First, a method to build the count density-distance curve for quasars was proposed. Then, the relative magnitude of quasars versus time was investigated, and led to a first order rate kinetics for the decay of quasars. From the first order rate decay, we could conclude that relative magnitude is a good measure of the quasar nuclear activity. We found out that quasars were formed by coalescence in a period between 10 and 12.5 Gyr ago. This observation provide…

I noticed no one has brought up this topic, so I have the honour to do it. I understand the principals, but I have a few questions: If a wormhole is created, it affects space and time all around it. The area around the wormhole is seemingly intact, but how does a wormhole affect everything else? I mean, can anybody else, who is not next to the wormhole feel that a wormhole is created? I understood that a wormhole dramatically decreases the distance between two points. Of all the models I saw, it makes a tunnel, but the tunnel has a certain lenght itself. But in the 1997 film "Event Horizon", they scrapped that idea and completely nullified the length of the tu…

Think about it: Jupiter is a gas planet. Stars are made almost entirely of gas. It has sixteen satellites that orbit it, some of which are even bigger than Mercury (now, the smallest planet). Stars have similar rocky objects orbiting them; they're called "planets." Jupiter emits its own radio waves. So do dwarf stars. Jupiter is so darn big, that if it were just a little bigger, it could probably perform fusion at its core (in fact, it already does; just not enough to heat a planet). Dwarf stars tend to be around that size. It seems to me that, had the conditions been only slightly different, we'd be living in a dual-star solar system right now. W…

Could dark energy be particles leaking off other branes?

Could it survive in a meteorite in space?? Would it burn up and be destroyed before it hit the earth?? also...what are the chances that we have seen every element in outerspace?? maybe theres something out there we could digest that keeps us awake for 7 days straight! there is probably a solar system with multiple earths out there...warring planets...we probably literally cant IMAGINE whats out there while i think its a good (overall peaceful) time to enjoy life i would like to know humanitys fate...i doubt living 10 generations on a giant spaceship in total darkness with no beaches or snow is much fun...im sure billions would be left behind...and even i…

IS it true that the sun is actually 7-8min behind it's true movement when we look at it from earth?

It is has become scientifically established that the sun will end its fuel and then it will change into a red giant that will come close to the earth swallowing all the nearby planets… this facts are stressed in the Holy Quran. By: Magdy Abd Alshafy The sun contains huge amount of matter. All of that matter produces a huge amount of gravitational force that squeezes the star inwards. In order to combat the inward crush resulting from the gravitational force, The Sun utilizes fusion power to hold itself up. This is the way the sun sustains its life and escapes collapse. How does the sun resist collapsing? At the Sun’s core, where the crush is most e…

I was thinking about all these SciFi stories about how massive amounts of shuttles, and or dropships entering the atmosphere in an invasion force; you'd need quite a lot of them, especially if you had deal with a continent's worth of military power. Now, would all those dropships, fighters etc. heat up the atmosphere when they enter? Enough to any invasion would be accompanied by a heat wave?

If the entire mass of the universe was compressed into a single point, it would form a black hole. What would be the radius of its event horizon? I calculated this from a mass of the universe of 10^52 kg, and it came out as around 10 billion light years. Is this right? If it is right then perhaps the whole universe is inside its own black hole. In which case where abouts is the singularity, and why aren't we sucked into it?

I know that the known universe is roughly 27 billion light years in diameter, but what about the unknown universe - that is, the universe even beyond what is visible? I used to assume it just wasn't known how big it was until I came across a chart the other day depicting the rate of expansion of the early universe. It was like this: Time: size: 10^-40s 1mm 10^-30s 100m 10^-20s Earth 10^-10s solar system 1s 10 Ly Now I'm not sure how reliably we can extrapolate this chart to today's universe. The rate of expansion has been changing after all. From what I understand according to the inflationary theory, the universe started out by accelerating, then deceler…

Lectures on inflation and cosmological perturbations by David Langlois arXiv:1001.5259v1 [astro-ph.CO] The above are notes based on lectures given at the Second TRR33 Winter School on cosmology, Passo del Tonale (Italy), December 2008. I have not read them very carefully, but they represent a modern and accessible introduction to cosmic inflation. To date, a hot big bang + inflation model has survived against its competitors as a good model of the early universe. It makes predictions of the fluctuations in the CMBR via quantum perturbation in the inflaton field. Observations seem to agree with this theoretical set-up. It is expected that future more …

Please ponder a planet's Gravitational Binding Energy (Joules): U = (2/5) G M2 / R Now, please ponder that planet's Specific GBE (J / kg): U = (2/5) G M / R It turns out, that for the Earth, the S-GBE is roughly 15x the Energy-per-Mass released by exploding TNT. Thus, even if the whole world was turned into TNT, and detonated, it wouldn't be blown apart, but would reform, from the fragments, from gravity. Earth is "strongly gravity bound" (as it were). Now, according to Ollivier, Encrenaz, et al, in Planetary Systems — detection, formation, and habitability of extra-solar planets (pp. 209-213), for rocky worlds of terrestrial-type bulk chemical compo…

As I understand it, the galaxies moving towards us are in our local galactic cluster. Since Andromeda is moving towards us at the current time I was wondering if using the shrinking universe analogy that is used to speculate that most galaxies that are moving away from us at one time were much closer to us at creation would suggest that Andromeda was farther away from us at our creation times. It would seem that this would have to be true or Andromeda would have already collided with us during expansion. Would the distances between now and then jibe with the rate at which it is coming towards us without being too far away at creation to be affected by grav…

http://en.wikipedia.org/wiki/Harmonices_Mundi Why is this? The angular velocities vary in accordance to the distance to the sun, moving faster at perihelion, but what of it? The planets were formed of the same elliptical proplanetary disk, which explains why the ratios correspond so well, but I'm assuming that the approximation to musical harmonies can't be coincidental.

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/990924a2.html "...is now thought that the Great Attractor is probably a supercluster, with Abell 3627 near its center..." The date on that NASA public outreach page is 1999. Anybody have an update? Additional detail? Wikipedia refers to the concentration around Abell 3627 as "ACO 3627" and says there could be an even more massive concentration ("Shapley") out beyond the G.A., discovered in 2005. http://en.wikipedia.org/wiki/Great_Attractor So the G.A. may have been "demoted" "The survey also confirmed earlier theories that the Milky Way galaxy was in fact being pulled towards a much more massive cluster of…

hi everybody, I studied some astrophysics back at college many years ago, and I remember having a really good text book on the subject...cant for the life of me remember the name or the author. Anyway I really wanted to "get back into" astrophysics, but not sure where to start. Can anybody recommend any decent textbooks for beginners which might help me brush up? Alternatively, am I better going down a video / DVD route?? Thanks in advance

The Universe is constantly expanding and as a consequence some very distant stars are moving away from us at speeds greater than the speed of light. This means that these stars will never be seen by us. If the Universe stopped expanding, or worse, started shrinking, the radiation from those distant stars would reach us. This is the case for every point in the Universe. Would the Universe be destroyed along with the Earth and all of humanity?

Im sorry if this doesant make sence,but If the gravity inside a blackhole pulls light into it when light is trying to escape but cant:wouldnt the invisible fource of gravity be faster than the speed of light? Because Gravity is a constant,where as light has its limitations.

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I read at the following site: http://www.pbs.org/wgbh/nova/elegant/view-glashow.html that the universe is not only expanding but doing so at an accelerated rate! We're expanding FASTER as time goes on. Is this true? What kind of force is behind this acceleration? What will become of the universe? PS - Scroll down to "Towards a unified field theory" in the link above where this is mentioned.

Hey. Ive seen recently in the news about ligh sails for space crafts. apparently they work by reflecting photons of light backwards and some momentum transfered from the photon to the sail. However, I thought that photons where massless and therefore had no momentum. Anyone know how these work?

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 …