Based on their observations concerning the motion ofthe galaxies, cosologists hypothesize the universe is do-?
958089
I don't know what cosologists are hypothesizing about.  Cosmologists on the other hand, are hypothesizing that the universe is expanding.
919010
Yes, you are completely right.  This is why astronomy is so important.  By looking at galaxies that are a billion light years away, we are seeing what those galaxies looked like a billion years ago.  Since we can see objects up to 13.7 billion light years away (corresponding to the age of the universe), we can see objects like galaxies as they appeared at a range of times, letting us develop more thorough hypotheses about how the universe itself has evolved, and what might lie in our galaxy's future.
405243
They worked together. Across the space-time continuum.\n\nYou obviously aren't in the know.
1062047
Astronomy is mostly an observational and descriptive field focusing on sky objects. \nCosmology, is physics applied to the mechanics and functioning of the cosmos. \n\nSo cosmology provides a theoretical background to explain what astronomy sees. \nRoughly, a cartoon would depict an astronomer looking through a telescope, while a cosmologist would be a guy scratching notes on a notepad while using a calculator. Of course, this would be only an approximation. Both use calculators and take notes... \n\n"Astros" derive from "astra", meaning stars. "Cosmos" (the same in greek), means "order, arrangement". And refers to the universe or existence as a whole (including stars, of course).  ;o)\n\nAstronauts and cosmonauts are exactly the same thing. \n\nHope I could clarify it a bit.
29633
Actually Einstein predicted the Big Bang before Hubble found the first observational evidence.\n\nEinstein found that in his theory of General Relativity that the universe as a whole should be either expanding or contracting. He didn't like this so he added an extra term the "cosmological constant" to balance the equations and have a universe that was not expanding or contracting. That sort of static universe was what was expected in those days.\n\nMeanwhile, Edmund Hubble began making observations in the 1920s from the Mt Wilson Observatory of distant "nebulae." He had discovered previosuly that many of this faint blobs, previously thought to be gas clouds, were in fact galaxies like our own Milky Way. This was a big surprise since previosuly the Milky Way was the only galaxy, or what they called at the time, an "island universe."\n\nSo, it was natural for Hubble to look at the spectra of some of these distant galaxies. What he found was that, except for a couple of very nearby galaxies like M-31 the Andromeda Galaxy, all the other galaxies had shifted spectra. That is, these other galaxies has spectra which were redshifted, indicating that they were moving away from us.\n\nFurther he found that the fainter galaxies (which on average are farther away) had the largest redshifts. This lead to the famous "Hubble's Law" that says that the observed redshift is proportional to the distance a galaxy is from us.\n\nEinstein found out about Hubble's discovery and realized what it meant - the whole universe is expanding. Although naively it looks like everything is moving away from us, all of space is expanding, so that an observor in any galaxy would detect the same thing - that every galaxy is moving away from them.\n\nThe usual analogy is to think of rasins in rasin bread. As the bread rises all the dough (space) expands, so the distance between all rasins (galaxies) grows. Thus from any one rasin (galaxy) all the rest look like they are moving away.\n\nEinstein realized that his "cosmological constant" was unneccessary. He famously called it his "greatest blunder" and that he could have officially predicted the expansion of the universe before Hubble confirmed it with observations. (And in fact, before Hubble's discovery, other scientists like Willem de Sitter and Alexander Friedmann used the equantions of General Relativity to calculate an expanding universe.) \n\nAt that point it was realized that if space is expanding that in the past it must have been all bunched up in one spot. Just before Hubble Georges Lemaître realized this and thought that at first there was some sort of "primaval atom" from which everything else came from.\n\nFred Hoyle didn't like Lemaitre's idea at all, not the least of which was because Lemaitre insisted that God started the whole thing. Hoyle developed a rival theory the Steady State universe, and dismissed the other type of ideas as a "hot big bang." Of course Hoyle's term, meant as a put-down, became the offical name. (Hoyle's Steady State Theory was a serious rival to the Big Bang until the 1960s and the discovery of the microwave background.)\n\nIt wasn't until 1948 that the modern aspects of the Big Bang were proposed by George Gamow and Ralph Alpher. These guys showed that from an initial explosion of compressed everything one would get the correct mixture of hydrogen and helium and other trace elements observed in the whole universe. That is, if one starts from a hot subatomic, compressed mixture and lets it go, it will recombine into the right ratio of atoms. (Right being the ration actually observed.)\n\nAnd so it goes from there, to much more observational evidence for the Big Bang, as well as lots of theoretical progress. At the moment we know that the old cyclical idea, that the universe expands and then contracts, is wrong. In fact the universe seems to be accelerating, tha
199058
Astronomers are always right except some theories. Because they are doing more than research for this every minute. And i believe that they are right about the black holes.\nBut to make sure that thing they need more research on this.
78705
I think you are confused a bit. If you look around at nature, it is incredibly complex. The more we study it and the more we analyze i and measure it, the more complicated it appears. \n\nThe scientific theories and laws are attempts to put some order into this mass of complicated observations, to try to explain what is happening. Predictions based on these scientific theories can be made, and if it is a good theory, then the prediction will be verified by data. \n\nThe big bang is just one theory for the origin of the universe that attempts to explain what we observe: hubble's law, the microwave background radiation, etc. It is an attempt to produce a simpler theory to explain a very complicated and confusing set of observations.
694313
it's just the way we observe galaxies moving away from each other.  The further out from each other they are, the faster away from each other they move.\n\nFrom this and by analysing measures done on large numbers of galaxies, and then by taking these velocities and distances but plugging in older times in the data, it was found that, well, at some point back in time, all that stuff must have been concentrated at one point.\n\nAs the quality of experimental data improved, the Big Bang was the only theory that survived.\n\nBut in the early days, it was far from the only proposed model, so it is not at all, as you seem to believe, that physicists decided that you had to "build with explosions" ;-)\n\n\nhope this helps
998540
apparently there are 4 galaxies which appear to be approaching us. this link may explain why....i don't quite get it...it's 3am...i'm tired.
1182960
The expansion of the universe causes distant galaxies to recede from us faster than the speed of light, if Comoving distance and cosmological time are used to calculate the speeds of these galaxies. However, in general relativity, velocity is a local notion, so velocity calculated using comoving coordinates does not have any simple relation to velocity calculated locally. In other words, the galaxies (or more accurately, galaxy clusters) do not physically move away from each other. Rather, the fabric of spacetime between them expands. This also explains the Inflationary epoch during the Big Bang, when the universe expanded from a size a hundred billion times smaller than a proton to approximately one hundred million light years in diameter in just 10-32 of a second.
777198
the Milky Way is a galaxy
634899
I don't know of one. Observations could be explained by having the Earth fixed and the Sun orbiting it. It's just that our laws of physics would have to change.
475806
space is a thing, astronomy is the study of it.
274902
oscillating universe\nIn astronomy, theory stating that the gravitational attraction of the mass within the universe will eventually slow down and stop the expansion of the universe. The outward motions of the galaxies will then be reversed, eventually resulting in a ‘Big Crunch’ where all the matter in the universe will be contracted into a small volume of high density. This could undergo a further Big Bang, thereby creating another expansion phase. The theory suggests that the universe would alternately expand and collapse through alternate Big Bangs and Big Crunches.
370362
I've been studying these issues alot more in the past year or two, and I find them incredibly compelling. \n\nWhen you look at the massive size of the universe, to assume that we are alone is, if only mathematically, ignorant to some degree. \n\nThe more I study history and astronomy, the more I think these two topics are combined. \n\nI may sound like some wackjob, but, I think that there is life elsewhere, that they have traveled here, and perhaps have had a hand in certain events in history. \n\nI don't believe in coincidences, and there are entirely too many questions in our past without answers that can be provided which point towards humans. \n\nWho knows - maybe I am a wackjob, but in the big picture, you can never question everything enough. \n\nIts a big, big universe. We all get wrapped up in our tiny lives, in our tiny houses, in our tiny countries, and forget about the stars, the galaxies that are out there. \n\nSome day I believe we'll find the truth, unfortunately I believe that this 'someday' will be thousands, if not hundreds of thousands of years in the future.
983642
Actually, they know it isn't infinite.\n\n\nThe findings are mostly thanks to hubbles big idea and discovery, but they can now confirm that indeed the visible universe is finite thanks to WMAP.\n\n\n\nAs for the possiblity of space outside of the visible universe...we have no idea.
1005703
By the red shifts of the measurement. Or to make a short story long it's the displacement of features in the spectra of astronomical objects, such as galaxies and quasars, towards the longer wavelengths, generally interpreted as a result of the Doppler effect due to their recessional velocities (i.e. how fast they're moving away from something) The expansion of the universe means that all but the nearest galaxies have redshifted spectra (in fact this is what led to the discovery of the expanding universe back in the 1920's). Hubble first described this back in 1925 that the redshift or recession velocity of a galaxy is proportional to the distance in relationship with the viewer. All that means is that by this redshift they were able to approximate the distance of these galaxies, and since they had these distances they could state them in light years (since light years is a distance, not necessarily a time)