Astronomy and Cosmology

hey..im currently working on a big research papaer talking bout the shape of the universe..i jus started and im alreayd confused..it seems that ther are three posibilities for the shape and that the universe is flat.what does this mean? flat would mean having a single flat plane..but how is that possible when space time actually curves..i mean isnt the universe have depth to it? how can it simply be flat..please help!

Looking at the Friedman solution for a fluid with a given pressure and energy density, we have: [math]H^2 = \left(\frac{\dot{a}}{a}\right)^2 = \frac{8 \pi G}{3}\rho + \frac{\Lambda}{3} - \frac{k}{a^2}[/math] Would someone mind walking me through how we arrive at a? Rev Prez

The Pioneer 10 and Pioneer 11 spacecraft, the ones which are mysteriously slowing down... http://archives.cnn.com/2001/TECH/space/05/21/gravity.mystery/ Anyway, I was at the Mill Hill Observatory (I got to use the Radcliffe telescope: http://www.ulo.ucl.ac.uk/telescopes/radcliffe/ or image here: http://www.ulo.ucl.ac.uk/images/ulo_photos/rad_modern.jpg it's the only time it has ever been open to public (it was open because of national science week)).... back to the topic!... I was talking to a PhD astronomy/cosmolgy guy and asked him about what he thought was the 'mysterious force' acting on the Pioneers, he reckoned, off the top of his head, either mathematics error…

I've heard this term, but am unclear on it's exact definition. I think it implies that the entire universe as we know it is just one "volume" inside of a larger universe. Is that an even remotely accurate definition?

While trying to help someone else in another thread I posted a Link for them to go to. They were trying to draw a map. What intrigued me is the Great Wall of galaxy cluster shown. I started this new thread to see if anyone has any theories about it. This is the map http://www.astro.princeton.edu/~mjuric/universe/ This is more info about the Sloan Great Wall http://emystics.org/newscienceparadigms/astro/great_wall.htm

this is a lively ongoing line of research in LQG a new paper by Bojowald et al just came out this month http://arxiv.org/gr-qc/0503041 A black hole mass threshold from non-singular quantum gravitational collapse Martin Bojowald, Rituparno Goswami, Roy Maartens, Parampreet Singh 4 pages, 3 figures Report-no: AEI-2005-020,IGPG-05/3-3 "Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a simple toy model of a collapsing homogeneous scalar field. We show that non-perturbative semi-classical effects of Loop Quantum Gravity cause a bounce and remove the classical…

Hi all, i'm not sure if this is the right forum for this but i think its more of an astrophysics question. Can somebody please give me the gist of dark matter/ dark energy? Is it like antimatter or what? Thanks in advance ~Scott

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Just a personal possible theory here. But what if instead of out of nothing came the Big Bang, that the Universe was just one Big Solid Mass with no Space. Then at some point a fracture occured. So therefore all the Mass we see has always been. The Space inbetween is what's new. Sorry for the lack of scientific terminology here.

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If not what is a planetary body? What do we consider a plantery body?

http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Riemann.html to be accorded the right to lecture at the university Riemann had to present a talk on something he prepared 3 lectures, two on electricity and one on geometry, and he let Gauss choose which he should give Gauss chose the one on geometry this talk was on the foundations of geometry and it showed how a space can have shape and curvature and all that good stuff without living in any larger surrounding space and without having any boundaries this talk was given in 1854 Georg Friedrich Bernhard Riemann lived 1826-1866. He was extraordinary creative, like Mozart, except it was in math ins…

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This might be the hardest question ever because it's questioning the size and dimensions of the universe. If the universe is infinite (space-time is flat and Euclidean), this simply means there never was a big bang at all. But if the universe is finite (space-time is curved and elliptic) but unbound (eternal but not infinite in size) then we, as 3D creatures, will never be able to see what lies beyond. A NewScientist article implies that the universe is finite but unbound.

Earth years - is this true or false.

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Does anyone know; were the Dinos the first walking animals on this planet? I believe they survived about 50 million years is that right? And I'm really confused to as how long have we've been around... some say only a million years yet fossils say we've been around for about 4 million years does anyone out-there know for sure?...us.2u

measusing changes in the apparent wavelength of lines in their stras spectrum (the radial velocity method) True or False?

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Take a look at these pictures. I hope everyone can access them, they came off the AOL home page. http://rl.channel.aol.com/space/hubblegallery Edited: I checked it from the Foxfire browser and it seems that you will need an AOL screen name--sorry.

Why can we not use the direction of other galaxies that are moving away from us and the speed they are traveling to triangulate the origin of the Big Bang. I mean all galaxies are most likely to still be moving away from the Big Bang which means if we can identify only a few galaxies to our so called Northe south east and west, and the speed and direction from us and us from them, We should be able to determine which direction all of them are going and triangulate the origin of the Big Bang. Right? We need to clone Einstein. \ . . . . / \ . . . / …

The standard big-bang cosmology is based on the cosmological principle, which assumes that the universe is homogenous and isotropic on large distances. We use the FRW metric. Since cosmic inflation is getting slight support, why do cosmologists estimate that the acceleration began roughly 5 billion years ago? If so, what hapanned before that which caused the universe to decelerate?

hi im currently studying physics in grade 12. I have an assignment due at the end of the week which asks for the most important discoveries to the model of the solar system/universe. The major events in history i am aware of i.e. the invention of the telescope and Keplers 3 Laws of Astrophysics, but i am unsure of the importance of the lesser contributions to the model. I would appreciate any contribution to the importance of the developments in the model of the solar system/universe.

i know about the expanding universe, and does that relate to the big bang? is the big bang still going on? is the 'expanding universe' just the big bang still continuing? + i heard that when the big bang began it exploded faster than the speed of light. And if the big bang is still happening, that means the 'end' of the universe has no light, is that possible?

First Nasa decided they don't have the money to keep the Hubble up and running and now Nasa is looking to scarp their currently operating unmanned missions. It's discussed here in this article. I think it's very sad that we could loose these probes right when the data they are returning is coming so close to fruitarian. We have the Voyager probes, which already have proved useful in finding error in classical Newtonian gravity, and are just now approaching the heliopause. Considering it's taken 30 years of funding to get them this far, why not wait until after we know how thick the heliopause is before we cut off all communications? The Ulysses is a sola…