Astronomy and Cosmology

What is the scientific definition of universe? What might divide ours from alternates?

Hello, I've been trying to understand the quantum fluctuation theory of the Big Bang lately. That's probably not the technical name of the theory, but it's the one that says the Big Bang is the result of a quantum fluctuation in the void--the spontaneous appearance of some particle or force or something that very quickly lead to a run-away inflation of spacetime and matter and energy. First of all, is there any credence to this theory among scientists? Second, what exactly "fluctuated"? Third, if from the Big Bang was create space a time, what time was there for any "fluctuation" to occur in such that it could give rise to time and everything else in it? …

Hi, Say the moon doubled in size magically, what would keep it from becoming part of the Earth again? I guess I'm asking what would have to happen to stabilze the orbit of the two objects if one just suddenly became larger ? Would one have to spin faster? or conversely move away from the other ?

http://www.abc.net.au/science/articles/2013/02/19/3693584.htm Apparently, the mass of the Higgs Boson has determined the fate of the universe. Submitted for your discussion.

Could anyone please explain to me how can an accelerated expansion take place in a homogenous & isotropic universe? I really can't figure that out - at all. Not only cannot happen radial, but not even linear. Unless I'm terribly wrong - and there's where you'll probably come in. If you even take the time for an (simple !) illustration, I would thank you even more. By the way, not only I cannot figure out dark energy, but I cannot imagine expansion even before DE - how could even a constant expansion, or a deccelerating one, could take place in a homogenous & isotropic three-dimensional universe? As soon as I think of several points in space and try …

Why don't the crew in the spacestation have living quarters that rotate for artificial gravity?

is there really any black suction theory exist ?

CDMS (cryogenic dark matter search) Very interesting these experiments, however I think they don´t use the most important propriety of the dark matter, the gravity attraction. I do think it should be done in another region of the earth, near the equatorial line or at least between the tropics. I think when the mass of the earth attracts these possible dark matter divert them from its original trajectory pulling them to the center of the earth. This new trajectory would cross the imaginary translational line of the earth and sometimes could take them to orbit, depending of the speed and height. If the experiments were done in this region, the site will coincide wi…

It was a once in about a hundred years event. A meteor of 50 feet across, about 10,000 tons, traveling 11 miles per second before impact, exploded 9 - 12 miles high with the energy of 30 Hiroshima bombs or 500 kilotons. It blew out windows 23 miles away. Anyone find any other info about this? I suppose something this large could have crashed over the ocean or desolate area, since the Tunguska event of 1908, without getting any attention, or could be mistaken for lightning and thunder. http://en.wikipedia.org/wiki/2013_Russian_meteor_event http://phys.org/news/2013-02-russia-asteroid-impact-esa.html

Hi everyone, alright my question is this, what are the reasons for such a strong and widespread belief that some dark, as of yet unobserved type of matter must be present in the universe? My knowledge of the topic is rather superficial but the way I reason is this, there is mathematically and physically appealing theory called general theory of relativity and for quite some time this theory has been repeatedly tested (with positive outcomes). The precision of the tests is nothing like the experiments in quantum mechanics, but hey, GTR always gave better predictions than any other theories and up to date. I think that only Brans-Dicke theory and some of the f( R) theories…

From my knowledge the theory of the accelerating expansion of the universe is based only on the observation of the Doppler effect. Is it possible that light's frequency is dropping (for some unidentified reason) traveling throughout the cosmos and the stars are moving away with a constant speed? If dark energy is blowing up everything (including us), then it is merely a question of perspective if the universe is expanding, or the forces that hold matter together are decaying. In the case of photons this process could also mean loosing frequency. Am I contradicting some scientific observations?

Considering the fact that the Universe is principally made up of Dark Matter, how is it that the spacecraft Voyager that started its journey about forty years ago and has travelled a billion or so miles in space has not hit/encountered Dark Matter?

I am struggling to find consistent information about where to look in the sky this evening for a chance to see the Neo (I am in outer London on northeast). Between Leo and the Plough seems the most regular advice from 8pm - but that's a big space and an uncertain time. I have tried pasting the orbital elements into fourmilab yoursky without success Any clues - preferable a sky map with a nice line drawn on it?

Hello everybody! Please, pay no attention to my bad English, because I’m non-native speaker. Just try to see the point. I had a debate with my acquaintance concerning the following issue: Is there any physical possibility that humans are under surveillance of extraterrestrials? By surveillance I mean observing individual people by means of optics with great magnification. Well, I believe it doesn’t happen. Here is my little analysis of this matter. Let’s imagine any possible ways of such surveillance and fantasize about them: 1. Optical telescopes in space (like spy satellites). Such telescopes need big aperture of main mirror to be able to…

http://www.nasa.gov/topics/solarsystem/features/asteroidflyby.html The simulation of the flyby doesn't seem to be correct. The attached image is my plot(s) for the flyby path of 2012 DA14. I had to reverse the side elevation, at least it was symetric, scale it, and plot each against the other as the NASA/JPL images and the simulation were in opposition. BTW, pink is the color you get when you reverse a dark image. I don't think it will hit, there is a possibility it will become a satellite, NASA only said it would not hit the Earth or any other planet although they made no mention of the moon which usually helps to capture quasi moons. The last image is fr…

Hello there, I am simulating a planetary system and there was some anomalies like Green atmospheres. That anomaly gave me the question of what kind of elements are present in that planet's atmosphere that makes it color green or simply what are the different compositions of different colored atmosphere? Our home planet Earth has blue atmosphere since its main components are nitrogen (78.09%), oxygen (20.95%), argon (0.93%), and carbon dioxide (0.03%). The atmosphere also contains small amounts, or traces, of water (in local concentrations ranging from 0% to 4%), solid particles, neon, helium, methane, krypton, hydrogen, xenon and ozone. The color of our atmosphere is …

the sun is losing mass faster than the earth is. so later in the future, the gravitational force beetween the earth and the sun should decrease. my question is, will this actually happen and if it does, will the orbit of the earth be stable or could it shoot out into the universe?

please comment if you want, we would like to know what you think ... http://www.youtube.com/watch?feature=player_embedded&v=zIrgQKm5mwQ

It seems to me that stars orbiting black holes would cause some gravitational distortions within the disk, and that these distortions might cause some of the black holes material to be ejecected out from the center of the phenominon much like the jets of quasar. If this is happening all the time the black holes would probably be shrinking at a regular or at least a prdedictable rate. Does this happen? or has this been considered in any theories? if so, does the material expand into stable particles? perhaps strong force particles with no structure to capture electro magnetic energy?

Here is something I discovered on another web site, that refers to "physics.org". "13 light years away: Earth-like planets are right next door February 6th, 2013 "Astronomers have found that 6 percent of all red dwarf stars have an Earth-sized planet in the habitable zone, which is warm enough for liquid water on the planet's surface. Since red dwarf stars are so common, then statistically the closest Earth-like planet should be only 13 light-years away. Credit: David A. Aguilar (CfA) "Using publicly available data from NASA's Kepler space telescope, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) have found that six percent of red dw…

Let’s suppose that Big Bang was prepared and initiated by some “Creator” in other Universe and that our Universe is located within it being a smaller part of it. Is it theoretically possible to “create” in such a way several completely identical Universes with identical future and evolution? I mean is it theoretically possible that aeons ago somewhere existed the same Universe as ours with the same creatures and living beings and with the same events? Thanks in advance.

I need to know about black holes like 1)mass 2)volume 3)speed 3.5)temperature 4)if something goes is black hole what will its speed 5)formation 6)destruction 7)what is its role in universe 8)can we produce them 9)how much it's powerful 10)can we damage black holes 11)is there any power in universe to destroy black holes 12)how much black holes are present in current universe 13)what is relation of black holes with time etc. these are some of question when we want to learn about bh please give answer to each question

So light red-shifts over time as it travels over vast distances of space, eventually to the point where it would be immeasurable by our current technology, but for the faint radio photons we do manage to pick up, how do we determine that it wasn't a photon that traveled in the opposite direction from it's sources and then looped around the universe in a 4 dimensional hyper-sphere?

Globular clusters have a few well known characteristics They contain only old stars All stars within a globular cluster are approximately the same age They contain very few heavy elements The heavier the supermassive black hole at the center of a galaxy, the more globular clusters orbit around that galaxy Based on the above I speculate that globular clusters around the Milky Way were formed by gas emitted from the jets of the supermassive black hole at its center, by the time our galaxy was a quasar. I've just had the thought this evening. Not that I would claim to be the first, it seems too easy of an idea to not have been proposed before. Anyway, what would …

If I know my physics correctly, the singularity at the center of a black hole has infinite mass. How can something that is infinite ever decrease in gravity? Wouldn't the pull of gravity from the black hole always be faster than the speed of light from any point in the universe?