Buffy Posted February 2, 2005 Report Posted February 2, 2005 I caught this in the Jan 15th Economist ("In the Beginning", http://www.economist.com/science/displayStory.cfm?story_id=3556105 if you have a subscription and missed it): At the meeting of the American Astrophysical Union in San Diego a few weeks ago, it was announced that a combination of results from the Sloan Sky Survey and the 2-degree Field Galaxy Redshift Survey on the fine grain structure of the Universe, that was intended to measure how much gravitational collapse has occured in the last 2b (2d) and 500m (Sloan) years. Comparing the two they got a much more exact breakdown of the amounts of matter, dark matter and dark energy in the universe, and it the numbers exactly match those necessary to show that the Universe is...FLAT! We've always known its been close (and of course one of those quinky dinks that some like to use as proof of multiple universes), but this is getting close to "fer shure." Unfortunately the Economist doesn't print names of these, and I haven't bothered to look, but I'll bet theres some interesting reads on the AAU site or in upcoming proceedings... Cheers,Buffy
lindagarrette Posted February 2, 2005 Report Posted February 2, 2005 Thanks, Buffy. Very interesting article! http://www.economist.com/science/di...tory_id=3556105
Tormod Posted February 2, 2005 Report Posted February 2, 2005 So there you have it. The universe is flat, infinitely prolonged, and the more common something is in it, the less we know about it. Oh, and as far as making planets is concerned, God may not play dice, but He is a mean hand at snooker. Good catch, Buffy.
Buffy Posted February 2, 2005 Author Report Posted February 2, 2005 Actually the other half of the article is about planet formation and is pretty interesting too, which is where the snooker joke comes from. Unfortunately of course, most folks in the US don't know playing snooker from canoodling in the boot! :hyper: Cheers,Buffy
alxian Posted February 3, 2005 Report Posted February 3, 2005 i always wondered about this topic galaxies have to be flat because of their spin but the universe exists in every direction. therefore the world =roundsystems existing within the influence of a larger mass (solar systems)(galaxies) =flat (planar)everything else =equidistantly volumetric (since we can see to a certain distance in every direction (spherically, space is a sphere for now. but intellectually we assume that space is infinite, limited only by our ability to capture light. perhaps if we can map out the regions based on masses and quirks in the behaviors of the objects at the current limit of what we can see we can extended our map of space a bit outside of what we can see)
Buffy Posted February 3, 2005 Author Report Posted February 3, 2005 galaxies have to be flat because of their spin but the universe exists in every direction. therefore the world =roundsystems existing within the influence of a larger mass (solar systems)(galaxies) =flatUh, this is actually cosmologically "flat" as in "not closed and not open either", not "flat as a pancake"... Cheers,Buffy
maddog Posted February 4, 2005 Report Posted February 4, 2005 Buffy is saying "flat" as in the radius of curvature is VERY VERY near 0.0 ! Which means flat ! ;) Maddog
alxian Posted February 5, 2005 Report Posted February 5, 2005 meaning even though there appears to be tons of stars there isn't much matter in the universe nothing acts on anything else??
Buffy Posted February 5, 2005 Author Report Posted February 5, 2005 meaning even though there appears to be tons of stars there isn't much matter in the universe nothing acts on anything else??Oh its acting all right! The article sez that they've figured out that 77% of everything is dark energy, with 5% dark matter and 18% plain ol' matter that makes up you, me the earth, planets, stars, black holes, and anything else we'd consider "real." Regular matter and dark matter both provide gravitational effects that suck things together. Dark Energy pushes the opposite direction! Between all this pushing and pulling, the argument has been "is the universe going to continue to its expansion and dissipate completely" (aka "open universe", but see below) or "there's enough matter to slow it down and suck it back together in a big crunch" (aka "closed universe"). Then there's the answer "neither: it'll keep expanding but right at the point beyond it slowing down enough to eventually get to a point where its closed." To make it more complicated, the difference between these three possibilities is based on the notion of how space is "curved." Einstein postulated that if the universe closed then if you shine a really powerful flashlight and wait long enough, it would shine on the back of your head (well, if it was a laser with infinite power and zero dissipation, but heck this is a thought experiment). In an open universe, light would also travel along a curved path but would go off forever and never come back to you (space is hyperbolic). In a flat universe, light actually follows a straight line (unless acted upon by a gravitational field!). Yow! Cheers,Buffy
alxian Posted February 5, 2005 Report Posted February 5, 2005 i'm made up of tardyons.. or is that retardyons...
Aki Posted February 5, 2005 Report Posted February 5, 2005 So that means there is no possible way for wormholes to exist??
Buffy Posted February 5, 2005 Author Report Posted February 5, 2005 i'm made up of tardyons.. or is that retardyons...NopeNopeNope. You got good questions! Keep asking em! Lots of good books on the topic. Try Coming of Age in the Milky Way, Tim FerrisThe Whole Shebang, Tim FerrisThe Inflationary Universe, Alan Guth (a bit tough and it does focus on early history of the universe)*A Short History Of Nearly Everything (Chapters 1-3 & 8), Bill BrysonCartoon History of the Universe, Larry Gonick (this one's great for beginners OR experts! Don't be fooled! This is not an Idiot's Guide!) I'm not actually a fan of Hawking's books: most people who said they read A Brief History of Time were lying! At least they bought it and tried! Cheers,Buffy
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