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Index of Subjects
Index of Subjects --_000_662E3D62D8C04C61B811727C09E501F9dalca_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Interference won't work either. Unlike water waves, which travel in a mediu= m, which can physically interact, light waves do not travel through a mediu= m at all, so they pass by and through each other with no effect. (In the last 1800s, Michaelson and Morley devised an experiment to look for= the "aether" though which it was though that light propogated. Their exper= iment proved there is no such thing. https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment) You can get waves to interfere with each other if they come from a single s= ource and pass though a narrow slit, and then a double slit, but the constr= uctive and destructive only occurs in a limited area, and affects their amp= litude, not their wavelength. Plus, the size of the slip would only affect = waves of a certain wavelength. You can prove this to yourself at a beach. T= ake a whole bunch of stick, and line them up in a row parallel to the shore= . Space them about 3 or 4 wavelength apart. The waves will just ignore them= . If you keep filling it to get the gaps close to the size of the wavelengt= h you will then see some interference and if you take lots of sticks and ma= ke the gaps a lot smaller than the wavelength, you will see that the waves = will now reflect off the barrier. (That is why radio telescopes can be made= with, what looks like chain link fencing material. The wavelength of radio= waves is sol long compared to the gaps that they just see it as a smooth s= urface. The other problem is that at the large scale the structure of the matter in= the universe is "frothy" like soap bubbles with large voids with almost no= galaxies, and galaxies found in sheets, filaments and lumped together in c= luster and supercluster where these come together. So any process that depe= nds on light interacting with matter, would have to produce identical effec= ts on electromagnetic radiation of all wavelengths, coming through all man= ner of distributions of matter AND give results that are exactly the same a= s those of an expanding universe which is predicted by relativity, a theory= which has passed (perfectly) every test we have been able to devise for it= as the technology to do so has advanced. Humans used to be comfortable with the idea that Earth was at the centre of= everything. Turned out we aren't but then we though we were near the centr= e of the Milky Way. It turned out that we aren't but we though that we were= in the only galaxy. Turned out we aren't, there are billions of them. Scie= nce does not care about what makes humans feel good..... The universe also is highly unlikely to have perpetual renewal. There was a= time when it was though that there was enough matter (including dark matte= r) to eventually slow the expansion. That is no longer the case. The rate o= f expansion appears to be increasing due to dark energy. This is an outward= "pressure" that appears to be a property of space-time (Einstein's cosmolo= gical constant that he later though was zero) and the universe expands, the= re are more and more cubic metres from which the dark energy can act. The e= ventual result is the heat death of the universe. There are already large prats (the vast majority, actually) of the universe= which is unobservable to us. As the expansion rate continues, more and mor= e distant objects will disappear. Almost all regular matter in the universe= is in the form of stars or gas and dust. For the vast majority of stars (i= ncluding the Sun), at the end of their life they puff off a bit of their ou= ter atmosphere and end up as a white dwarf star. They can no longer produce= energy and slowly cool off becoming black dwarves. They are quite small=85= the mass of the Sun packed into a ball the size of Earth and kept from col= lapsing farther by electron degeneracy pressure. For the small number of stars about 2-10 times the mass of the sun, they en= d up producing a supernova explosion, throwing some material back into spac= e with the rest ending up as a neutron star. Again, they can no longer prod= uce energy and slowly cool off becoming black. They are even smaller=85 the= mass of the Sun (or a bit more) packed into a ball the size of Halifax and= kept from collapsing farther by neutron degeneracy pressure. The really massive stars end up as black holes as they have so much leftove= r mass that neutron degeneracy pressure cannot stop the collapse. On the lo= w end they produce supernova and end up as a black hole=85 on the high end = they simply wink out leaving behind a black hole. So all stars end up as a dead object that either slowly cools off, or in th= e cases of black holes go cold right from the start. You can always make mo= re stars, but there you run into a problem. You need gas* and dust** from w= hich to form them. About 25% of the galaxies are classed as elliptical. They used up all their= gas and dust in a massive burst of star formation when they formed. As the= stars in there galaxies "turn off" they cannot be replaced. The Milky Way = is classed as a spiral galaxy and about 70% of galaxies fall into this type= . About 15% of their mass is still in the form of gas and dust, so they, at= least for now, they are capable of forming new stars, but a time will come= when they too run out of gas and dust. About 5% of galaxies are "irregular= " and while they have about 50% of their mass in gas and dust they are quit= e small. It is though that many of them formed from collisions between spir= al galaxies (common in clusters) an the stars are so far apart they can eas= ily pass through each other, the same cannot be said of clouds of gas. They= are also undergoing massive star formation, likely due to the shock waves = in the gas caused by the encounter. So, in the grad scheme of things, a bit depressing, but as there are still = many billions of years to go, I would not be too worried about it, especial= ly as the Sun is going to fry the earth in about 4 billion years when it go= es through its red giant phase..... Pat *The gas in our galaxy is 97% hydrogen and helium, with the other 3% compos= ed of metal. Note that in astronomy, "metal" is the term used for all the c= hemical elements which are neither hydrogen nor helium.. The early universe= started with no metal. Again, observ