An easy way to explain this 180 degrees, less than 180 degrees, more than 180 degrees garble is like this: Take a sheet of paper. Draw a right-angled triangle (it doesn't have to be right-angled, but this helps explain the following examples). Add up the angles. 180 degrees. Voila! This is your flat universe. Now, take the Earth. The whole thing. It doesn't have to be the Earth; it could be the sun, or a rubber ball. Pick any two points on the equator. Connect these two lines with a big pencil. Now, remember grade 4, where you were taught all longtitudnal (sp?) lines ended up at one of the poles? Well, take your two points and draw straight north from each of them. Both end up at the north pole! So you will have two 90 degree angles, plus an x degree angle. More than 180! This is a spherical, or closed universe. Now for this last one, let's take that hollow rubber ball, and cut the top half off. We're looking in on a bowl-like shape. Draw a triangle inside. The angles add up to less than 180. This is your saddle, or open universe. This makes sense, if you flatten out the earth or the open bowl. If you do this, your triangles won't really be triangles at all; your flat earth will have pushed in sides, and in the bowl the triangle's sides will stretch outwards. The theory behind the closed (spherical) universe is that, given enough mass, the universe will close in on itself, somewhat in the way in which the Earth is closed on itself. In the open (saddle) universe, there isn't enough mass, so the shape of the universe is that of a parabola (A 'U' type thing, except the sides keep moving outwards instead of being parallel). Lastly, the flat universe has a perfect quantity of mass, meaning its shape is not curved in any way. If you go from the Earth to Pluto, you're going in a perfectly straight line (well, you're really going in a straight line in whatever universe you're in; but remember, like with the triangle sides, if you are in an open or closed universe you would appear to be moving in a curved line to an outsider. This shows how in an open or closed universe, the shortest distance between two points is _not_ a straight line. This shortest distance is called a geodesic. But now I'm off topic.) In an open universe, since it does not have enough mass, the galaxies will continue to fly apart from each other, forever and ever. On the flip side, in a closed universe, eventually the force of attraction between the galaxies will be strong enough to slow down this acceleration, and the galaxies will then move back together into a Big Crunch. And again, lastly, in the flat universe, the mass of the universe is just enough to stop the acceleration apart, but not enough to start bringing it back together. Therefore, it will just stop and be still, and we'll live in a static universe. You can see how important it is, then, that we detect the enigmatic "dark matter". This invisible matter could account for up to 90% of the mass of the universe, and is really the button to whether our universe is open, closed, or flat. There is not enough detected mass in the universe to allow for a closed universe. We need dark matter. You can also see how favourable the closed universe is over the other options. A Big Crunch would give way to another Big Bang (in fact, this is not necessarily the first 'universe'; there could have already been a hundred, or a million, or infinite universes before this), and this would continue. This is the theory of the oscillating universe, and it's really preferrable to believe this as opposed to the thought of the universe going cold and dark forever. I'm personally skeptical of these findings implying a flat universe, as it just seems unlikely to have a _perfect_ amount of matter (well, it's within a range, but it's still rather precise on a universal scale) to allow for a flat universe. I'll keep my eyes open, but what I'd really like conclusive evidence of a closed universe! You don't always get what you like, though. Anyways, I just intended to explain the triangles, but I went way overboard. I guess this is just a topic that interests me! Best wishes, Mark Ferguson
Slashdot Mirror
Sounds to me like a Magic Eye. Very uh.. odd. I can't imagine people being that enthusiastic about "looking past the screen" to get the correct image.
Sorry about that all being one big paragraph.
:)
This is my first time posting on slashdot. I didn't realize I needed to insert paragraph formatting manually.
An easy way to explain this 180 degrees, less than 180 degrees, more than 180 degrees garble is like this: Take a sheet of paper. Draw a right-angled triangle (it doesn't have to be right-angled, but this helps explain the following examples). Add up the angles. 180 degrees. Voila! This is your flat universe. Now, take the Earth. The whole thing. It doesn't have to be the Earth; it could be the sun, or a rubber ball. Pick any two points on the equator. Connect these two lines with a big pencil. Now, remember grade 4, where you were taught all longtitudnal (sp?) lines ended up at one of the poles? Well, take your two points and draw straight north from each of them. Both end up at the north pole! So you will have two 90 degree angles, plus an x degree angle. More than 180! This is a spherical, or closed universe. Now for this last one, let's take that hollow rubber ball, and cut the top half off. We're looking in on a bowl-like shape. Draw a triangle inside. The angles add up to less than 180. This is your saddle, or open universe. This makes sense, if you flatten out the earth or the open bowl. If you do this, your triangles won't really be triangles at all; your flat earth will have pushed in sides, and in the bowl the triangle's sides will stretch outwards. The theory behind the closed (spherical) universe is that, given enough mass, the universe will close in on itself, somewhat in the way in which the Earth is closed on itself. In the open (saddle) universe, there isn't enough mass, so the shape of the universe is that of a parabola (A 'U' type thing, except the sides keep moving outwards instead of being parallel). Lastly, the flat universe has a perfect quantity of mass, meaning its shape is not curved in any way. If you go from the Earth to Pluto, you're going in a perfectly straight line (well, you're really going in a straight line in whatever universe you're in; but remember, like with the triangle sides, if you are in an open or closed universe you would appear to be moving in a curved line to an outsider. This shows how in an open or closed universe, the shortest distance between two points is _not_ a straight line. This shortest distance is called a geodesic. But now I'm off topic.) In an open universe, since it does not have enough mass, the galaxies will continue to fly apart from each other, forever and ever. On the flip side, in a closed universe, eventually the force of attraction between the galaxies will be strong enough to slow down this acceleration, and the galaxies will then move back together into a Big Crunch. And again, lastly, in the flat universe, the mass of the universe is just enough to stop the acceleration apart, but not enough to start bringing it back together. Therefore, it will just stop and be still, and we'll live in a static universe. You can see how important it is, then, that we detect the enigmatic "dark matter". This invisible matter could account for up to 90% of the mass of the universe, and is really the button to whether our universe is open, closed, or flat. There is not enough detected mass in the universe to allow for a closed universe. We need dark matter. You can also see how favourable the closed universe is over the other options. A Big Crunch would give way to another Big Bang (in fact, this is not necessarily the first 'universe'; there could have already been a hundred, or a million, or infinite universes before this), and this would continue. This is the theory of the oscillating universe, and it's really preferrable to believe this as opposed to the thought of the universe going cold and dark forever. I'm personally skeptical of these findings implying a flat universe, as it just seems unlikely to have a _perfect_ amount of matter (well, it's within a range, but it's still rather precise on a universal scale) to allow for a flat universe. I'll keep my eyes open, but what I'd really like conclusive evidence of a closed universe! You don't always get what you like, though. Anyways, I just intended to explain the triangles, but I went way overboard. I guess this is just a topic that interests me! Best wishes, Mark Ferguson