QUOTE(Dr.Shotgun @ Sep 24 2005, 02:03 PM)
About space:
There are three posible shapes of space: A cube, a sphere, and a reverse sphere. If it was a sphere, you woukld never reach the end, same with the reverse sphere. If it was a cube, the sides could "wrap around" like a pacman screen.
Read The Fabric of the Cosmos by Brain Greene.
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I like to think of it as a reverse eliptoid sponge.
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QUOTE(synd)
[cate,Sep 22 2005, 12:38 AM]Particles in the water absorb certain frequencies of light and some of those that aren't photons that aren't obsorbed make it back to the surface (then observed by your eye). There is also some ideas on these particles also scattering light, I didn't quite understand what it ment but most likely related to some form of refraction.
The color may be related to the color of the sky but only partially.
People often say the the sky is blue because the oceans.. and is funny because people say the ocean is blue because of the sky. We do know however the blue sky is a result of the chemical makeup of our atmosphere so we can safely say only the sky contributes to the oceans blueness and not the other way around.
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This should explain everything.
.QUOTE(Webxhibits.org)
Water has an intrinsic color, and this color has a unique origin. This intrinsic color is easy to see, as can been seen in the Caribbean and Mediterranean Seas and in Colorado mountain lakes. Pure water and ice have a pale blue color, best seen at tropical white-sand beaches and in ice caves in glaciers (green colors are usually derived from algae). It is neither due to light scattering (like the sky), nor dissolved impurities (e.g., Cu2+). Because the absorption which gives water its color is in the red end of the visible spectrum, one sees blue, the complementary color of orange, when observing light that has passed through several meters of water. This color of water can also be seen in snow and ice as an intense blue color scattered back from deep holes in fresh snow.
Water owes its intrinsic blueness to selective absorption in the red part of its visible spectrum. The absorbed photons promote transitions to high overtone and combination states of the nuclear motions of the molecule, i.e. to highly excited vibrations. To our knowledge the intrinsic blueness of water is the only example from nature in which color originates from vibrational transitions. Other materials owe their colors to the interaction of visible light with the electrons of the substances. Their colors may originate from resonant interactions between photons and matter such as absorption, emission, and selective reflection or from non-resonant processes such as Rayleigh scattering, interference, diffraction, or refraction, but in each case, the photons interact primarily or exclusively with electrons. The details of the mechanism by which water is vibrationally colored will be discussed in the paragraphs which follow.
Laboratory observation of the vibrational transitions that give water its color requires only simple equipment. The graph at right gives the visible and near IR spectrum of H2O at room temperature. The absorption below 700 nm in wavelength contributes to the color of water. This absorption consists of the short wavelength tail of a band centered at 760 nm and two weaker bands at 660 and 605 nm. The vibrational origin of this visible absorption of H2O is demonstrated by the spectrum of heavy water, D2O. Heavy water is chemically the same as regular (light) water, but with the two hydrogen atoms (as in H2O) replaced with deuterium atoms (deuterium is an isotope of hydrogen with one extra neutron -- the extra neutron that makes heavy water "heavy," about 10% heavier). Heavy water is colorless because all of its corresponding vibrational transitions are shifted to lower energy by the increase in isotope mass. For example the H2O band at 760 nm is shifted to approximately 1000 nm in D2O.
Hydrogen bonding makes liquid water more colorless than gas. Water is unique among the molecules of nature in its high concentration of OH bonds and in its plentiful supply. Most important, the OH symmetric (v1) and antisymmetric (v3) vibrational stretching fundamentals are at high enough energy so that a four quantum overtone transition (v1+ 3v3) occurs just at the red edge of the visible spectrum. These gas phase transition energies are all shifted to slightly lower energy by the hydrogen bonding of liquid water.
The role of hydrogen bonding can be determined by comparing gas and liquid phase water. When comparing the vibrational transitions of gaseous and liquid water, the liquid phase OH stretching band centered at about 3400 cm- 1 is red-shifted from the gas phase values of v1 and v3 by several hundred wavenumbers. This shift is primarily the result of hydrogen bonding in the liquid. The shift to lower energy induced by hydrogen bonding is seen most clearly in a comparison of the stretching frequencies observed for monomeric and dimeric water in a solid nitrogen matrix. While the monomer OH stretching bands v1 and v3 are slightly red shifted (ca. 25 cm-1) from gas phase energies by the matrix, the frequency of the dimer (with hydrogen bonding) OH stretch involved in a hydrogen bond was red shifted to 3547 cm- 1. That is 105 and 209 cm-1 below the gas phase values of v1 and v3, respectively. The near IR absorption bands of ice are the most red-shifted of all.
As the temperature is increased, hydrogen bonding decreases in importance to the point that at 375º C the liquid peaks are only an average of 80 cm-1 below the gas phase transitions. The red absorption which gives rise to the blue color of liquid water can be plausibly ascribed to high energy vibrational overtone and combination bands which, like the other vibrational transitions, have been shifted to lower energy by hydrogen bonding. Also, as the temperature of H2O is lowered, the band near 760 nm shifts to lower energy but also broadens enough to slightly increase the intensity near 700 nm. However, the changes are small enough that the color of water should not vary significantly with temperature between 0 and 50º C.
Hydrogen bonding in water causes the stretching frequencies of H2O to shift to lower values, making water more clear. If water did not have hydrogen bonds, it would still be colored, perhaps even more intensely than is actual water.
One might assume that some other hydrogen-containing liquids and solids beside water, such as liquid ammonia, could possess traces of bluish color because of similar effects. However, water and ice are the only two chemical substances we normally have the opportunity to observe in pure form in sufficiently large bulk so that a weak coloration becomes detectable.