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From	Message
archangel_777 17-Jan-13, 21:09	Black holes If you could get near the event horizon of a black hole, seem to me you'd be completely destroyed, or do scientists still theorize that its a way to another time, and place in the universe.
gblaze 30-Jan-13, 18:01	I believe it's worm holes where that is theorized possible, the show Farscape was based on that theory. I felt it did a good job of making it seem realistically possible and kept it entertaining. I recommend it if you have Netflix.
archangel_777 31-Jan-13, 06:34	Thanks, i will check it out
eyero5 24-Apr-13, 09:01	Black holes I have read that beyond the event horizon the laws of physics do not hold.Also that time stands still .This boggles my mind. If someone can give me a better understanding I would very much appreciate.
archangel_777 24-Apr-13, 15:54	No water on the Moon If the earth, and the moon were basically formed around the same time, give or take a few million years, and some of the gas giant moon's seem to have water on the surface. The moon is large enough to have gravity, then it puzzles me how the moon is ocean-free?
lord_shiva 11-Sep-14, 01:12	Lunar Water There is ice in polar craters on the moon--places where the sun does not shine. The moon formed after the earth, from the debris of a collision between the earth and a Mars sized body. This explains the lighter elements of the moon. It formed outside Earth's Roche Limit within just a few thousand years from the debris ring encircling the Earth after that collision, some 4.5 billion years ago. This would have been roughly 400 million years after the earth itself formed. Mercury and Venus have no moons, but Mars has two (probably captured asteroids--they are very small). Jupiter has like 60 of them, with Ganymede being the largest. Titan is the largest moon of Saturn, and the only moon in our solar system with an atmosphere. It has seas, but not surface water. The seas there are ethane, methane, and propane. Some of Saturn's moons are composed of cometary materials--frozen CO2, H2O, and a smattering of organics. Pluto and Charon are largely ices.
lord_shiva 11-Sep-14, 01:19	Black Hole Time Gravity slows time, and the event horizon of a black hole is the ultimate time stopper. So time stops at the event horizon, but inside a black hole who knows? Time might be imaginary, or even reversed. Probably not, but we don't have a good handle of the other side. For SBMR--stellar sized black holes would have strong tidal forces that shred approaching matter, liberating x-ray radiation. Cygnus X-1 is an X-ray source as it pulls (and shreds) gas off a companion star. The difference in the pull of gravity at your feet and between your head would be enough to rip you up--you couldn't survive it even in the strongest space capsule which itself would be pulled apart. Around really big black holes the force differential might be small enough to avoid shredding--if you were moving fast enough and far enough out. Theoretically you might be able to use gravitational time dilation to travel into the future. Some physicists have proposed there might be ways to use black holes to create "Einstein-Rosen" bridges--essentially folds in space to distant places. On the other hand, there are sound theoretical reasons FTL travel is not possible. It violates causality.
knightrider62 29-Sep-14, 08:31	.What is FTL time travel? What isFTL time travel?Last year it was proposed by some scientists that the theory of time travel was possible.
lord_shiva 29-Sep-14, 10:17	Faster Than Light If time travel is possible FTL might be possible. Einstein's relativity discounts the possibility of FTL travel. Information cannot propagate faster than... I forget what it is called. The "world event" bubble. Light is absolute, and for this reason Einstein proposed calling it his "theory of absolute." He settled on "relativity" because of the overall emphasis on the relative nature of frames of references. World lines, maybe. If FTL was possible we could send a ship to a distant star which could then broadcast messages back that appear to have been issued before the ship could have arrived. This violates causality, a fundamental precept of physics (like conservation of mass/energy, momentum, charge, etc.) The first few experiments to detect tachyons (supraluminal particles or particles that never travel slower than light) failed, and it appears we've run out of ideas for means of detecting tachyons. Our universe is prosaic tardyons, and that is all. Travel forward in time--no problem. Easy-peasy. Travel backward in time? To do that you must restore the universe to its prior state. Imagine the energy involved in reversing entropy. Drawing starlight back towards the stars from which it was unleashed. Moving rocks back up mountains. These effects do not appear reversible. So time travel itself seems unlikely. It might be possible to travel to a similar, parallel universe that existed at a point earlier than ours. But it would not be OUR universe, otherwise at any point to which we might wish to return we would have done so. Suppose you want to see Jesus crucified. There would have been travelers from the future congregating at that point in our own history. We don't know of them--so (probably) there weren't. It is unlikely we can even rob light from events in our distant past. The best we could hope for is the return of distorted signals warped around black hole event horizons. Good luck!
knightrider62 29-Sep-14, 10:55	thanks, for your reply. Things a lot clearer now. anything on the latest about Black holes. Suppose for time being nothing further can be known. As when all is said and done know one is going to come back and tell the tale!
lord_shiva 29-Sep-14, 12:28	Time Travel Richard Feynman postulated a decay mode in quantum mechanics in which part of a virtual particle propagates backwards through time--albeit very briefly. It seems like backwards travel might be theoretically possible, but only for the most fleeting of moments. You can look up stuff on electron/positron annihilation and Feynman diagrams. Some folks say he did it just as some sort of shortcut to make the math work easier--and that positrons do not actually briefly propagate backwards through time. I don't really have a horse in this race so it doesn't make any difference to me. I wondered once if it might not be possible to improve lottery guesses by measuring decay events of medium half life substances (minute range) by placing the isotope in containers after the numbers are drawn. We're talking time scales many orders of magnitude larger than positron temporal retrograde motion, and no actual connection between post draw decay events and pre-draw measurements. So far as I know, no one has ever measured any radiation increase BEFORE a radioactive substance is brought near or prodded into some chain reaction. And standard nuclear decay really isn't tied to positron/electron annihilation anyway. It was just an entertaining random thought. You know--like animals being sensitive to "microquakes" preceding a major tectonic event.
lord_shiva 29-Sep-14, 12:42	Triple Black Hole Galaxy From NASA APOD (Astronomy Photo of the Day) apod.nasa.gov The two big holes each mass roughly 100 million solar masses (decent size--our galaxy's black hole is only 4 million solar masses). The two big ones are about 500 light years apart. Some people believe black holes do not exist, that there are other (possibly even better) explanations for what we observe. I have a friend who thinks the LIGO scientists are just kidding themselves--that gravity waves do not exist (and Einstein was therefore mistaken). I don't hold any human being up as infallible. Einstein might very well have been wrong about some things. He WAS wrong about the fudge factor. He THOUGHT he was wrong for introducing it, but it turns out he was right about that--he just had the sign wrong (expansion rate of universe is INCREASING). The Gravity B probe tested Einstein's frame dragging conjecture--one of the last things Einstein postulated that had yet to be confirmed. Turns out he was right about that. Einstein really nailed a great many things. He is one of the guys who postulated the existence of black holes. Artist's image of accretion disk for a small (seven solar mass) black hole, like what would be associated with GRO J1655-40: apod.nasa.gov
lord_shiva 07-Dec-14, 19:59	"Imaging" Black Holes Ran across this article in Yahoo Finance today: finance.yahoo.com This is for the benefit of gameknot.com, who asked about recent developments in black hole theory. I attended a lecture on black hole/neutron star collisions Friday evening--quite fascinating. The standard explanation for the origin of heavy isotopes (heavier than iron) apparently has some flaws, in that the neutron cloud emitted from a supernova would then be shot through by neutrinos, decaying the material available for heavy nucleosynthesis into a proton gas. When you are in the vicinity of a supernova, there are a LOT of neutrinos. So many that you'll get multiple hits in a detector (like Kamiokande) 170,000 light years away. There is a line from hydrogen out past Uranium connecting stable isotopes to nuclear mass. Every element is distinguished by its proton count (1H, 2He, 3Li, 4Be, 5Bo 6C, etc.), but the nuclear mass varies by neutron count. So Hydrogen has three isotopes--two of which are stable. H & H2 (deuterium) and H3 (tritium--half life 12 years or so). 1H1, 1H2, 1H3. You might be able to smack on a fourth neutron momentarily, but it won't stay. Instead what will happen is that you will bump hydrogen up to helium--you will transmute it into a new element. So by power of the S process tritium transmutes by neutron capture and beta particle emission (mediated by a W boson of the weak nuclear force) to Helium 4. 2He4. Helium is an alpha particle (named back when we didn't understand radiation very well). And, uhm, beta particle--high speed electron ejected from the atomic nucleus. Where does it come from? Turns out neutrons weigh slightly more than proton/electron pairs combined. You could think of a neutron as the combination of a proton/electron, and the additional mass (mass defect) is converted to energy imparted to the electron to expel it during neutron decay. Free neutrons have a half life of 12 minutes. So back to the line. The R process (S=slow, R=rapid) occurs in core collapse supernova. There are a LOT of neutrons suddenly available for manufacturing stable nuclei. Normal stars cannot do this--they cannot synthesize elements heavier than iron because it takes more energy to create such isotopes than is liberated. Mm, isotope. 1H1, 1H2, 1H3 are all isotopes of hydrogen. An isotope has the same number of protons, but is distinguished by varying atomic mass (number of neutrons). To emphasize: Atomic NUMBER = number of protons which dictates the element. Atomic MASS is the sum of protons and neutrons in the nucleus. Let's do the line one more time. You have all these neutrons smacking into nuclei, but the laws of nature say you can't have nuclei too heavy. You can't have hydrogen 4, or hydrogen 5, etc. So one of those neutrons splits, energy is liberated, and the atom migrates down the periodic table sort of like it was fusing. The old image (that I had) of disparate atomic masses smacking together and sticking just isn't the way atoms are made. There is no reverse fission process. Instead atoms are built the old fashioned way--up one neutron at a time (mass increase), then beta emission (atomic number bump and grind). So you get this line that sort of trails off into super transient elements with half lives so brief they break within the tiniest fractions of a second. But then, dangling WAY (TF) out beyond rationality the ratio of protons to neutrons drops down to about 10% and you get these (essentially) atomic nuclei that are a quarter mile in diameter. A substantial fraction of a stellar mass would be packed into such a sphere. Surface escape velocity would be relativistic--pushing 20% of the speed of light. We call these objects "neutron stars." Now, you might think a neutron star/black hole collision would be exceedingly rare, and for bodies in OUR neck of the universe you are right. But we have modeled the dance of stellar bodies (swing your partner round and round, do si do), and as they merge the neutron star ends up sloughing off a substantial fraction of mass. I'm not sure about roche limits of such bodies, but this material gets flung out at 20% of the speed of light. It is neutronium, and free neutrons begin decaying ferociously. There is a lot of energy available for R process heavy nucleosynthesis, and the models accurately fit observed isotope ratios. All that gold in your wedding band? It might very well have formed from a black hole/neutron star merger, maybe close to six billion years ago, rather than as the result of a supernova as you've been told. We think some gamma ray bursts are signatures of these events broadcast from billions of light years away.
lord_shiva 09-Dec-14, 18:47	Corrections I heard back from the lecturer today--there are a number of things I got wrong and a few that require clarification. Will post later.
archangel_777 11-Dec-14, 15:33	Black holes ive always heard that nothing can escape the gravity pull of a black hole, not even photons, then how can gamma rays shoot out from the north and south axis?
lord_shiva 11-Dec-14, 16:48	Black Hole Emissions The gamma rays were not in the hole, but were generated via powerful magnetic fields encompassing the black hole, created by the accretion disk. Herbig Haro Objects do essentially the same thing, spin matter into highly collimated bipolar jets of matter and radiation, though on a much smaller scale. The truly amazing ones are the quasars, galactic sized black holes ejecting particle beams that stretch out across hundreds of thousands to millions of light years. Imagine your home galaxy being intersected by one of those. Titanic forces wreaking havoc. The early universe was a much less pleasant place that what we enjoy now.
lord_shiva 11-Dec-14, 17:43	Hawking Concedes Back in 1975 Kip Thorne bet Stephen Hawking Cygnus X-1 was a black hole. Fifteen years later Hawking conceded--concurring the evidence was sufficiently compelling X-1 was indeed a black hole. It has a mass of nearly 15 suns, but a radius that is just under 30 miles. These dimensions would make it a black hole. You cannot pack 15 solar masses into a sphere that small without exceeding relativistic escape velocity. It's the law. 186,282.4 miles per second. Thou shalt not exceed this speed.
archangel_777 11-Dec-14, 18:43	Do you feel that a pulsar is a black hole reversed from a connecting universe.
lord_shiva 11-Dec-14, 19:37	Pulsars No, pulsars are rapidly spinning neutron stars radiating long (radio wave) electromagnetic spectrum. Some thought quasars might be "white holes" connected to black holes in another universe, but we now believe these are just galactic "herbig haro" objects powered by super massive black holes. Quasars are black holes too, heralding from an earlier, more chivalrous (or medieval) age of the universe, lancing out bipolar jets atop their steady black stallions...
archangel_777 11-Dec-14, 19:40	My mistake, I did mean quasars
eyero5 23-May-16, 13:27	Black holes in galaxies. Is it true that all galaxies have black holes in their center of rotation ?
lord_shiva 24-May-16, 08:26	Galactic Black Holes It was thought only spiral galaxies possessed black holes at their core, but we now know all (or almost all) galaxies have big black holes. Our galaxy's hole measures twenty million solar masses. The nearest quasar galaxy boasts a twenty BILLION solar mass black hole. The collision of two black holes was detected by LIGO, near my home, last year. One was 29 solar masses, the other thirty six. The result was a 62 solar mass black hole. Three solar masses was converted into energy, bled away through powerful ripples in space time itself. This event was orders of magnitude more powerful than the biggest supernova ever seen.
lord_shiva 24-May-16, 08:28	Collision The collision was a little over a billion light years away, not all that near my home. Just clarifying.
mo-oneandmore 24-May-16, 11:44	shiva Thank you for the clarification. I was almost did an appropriate response to your "near my home" statement.
brigadecommander 29-Mar-18, 04:33	question? does Newtons third Law of Motion (For every action, there is an equal and opposite reaction.) mean anything in the context of Black holes.?? If a black hole gravitationally pulls in all material near it, what would be the opposite effect of this Action? As suggested in the third Law.
brigadecommander 29-Mar-18, 04:36	correction meant to say;''What is the Opposite reaction to this Action?""
lord_shiva 29-Mar-18, 07:22	Black Holes Obey As matter falls towards a black hole, the black hole falls towards the matter. Black holes obey physical laws--they just also stretch spacetime beyond its breaking point (from our perspective).
brigadecommander 29-Mar-18, 07:46	so you think there is no 'other side' to a BH. Nothing coming out the other side to balance whats going in?. I don't think we understand BH's much at all. And if and when we do,it will go a long way to understanding more of the Cosmos. BH's seem to be a dynamic part of the structure. Like a valve or something. Or not....
inhis_service 30-Mar-18, 17:09	Second Law of Thermodynamics This Christian, yours truly, is reading these posts/ comments by non-believers in the God I believe in just ooing and aweing over our incredible world/ universe. Which is fine as far as that I, too, ooh and awe with you. However, just because I am a Christian, and a man of faith, does not mean that I am not unaware - I am - of a certain thing called the second law of thermodynamics. Especially as it relates to the principal within this law called entropy. Here is a video primer on this subject. www.khanacademy.org The point of which is that all of this fabulous complexity over which we ooh and awe is not by happenstance.
lord_shiva 31-Mar-18, 08:25	Second Law The temperature of a given reservoir cannot be reduced to absolute zero through a finite series of operations. You may not have ever heard the second law phrased this way, but it is an equivalent statement. The second law does not stipulate Christ died on the cross for our sins, or that local reversals of entropy are impossible. Can entropy be reversed? On the largest scale, no. Overall entropy in any isolated space must increase over time. Nevertheless, Earth enjoys three sources of energy. First is the enormous fusion reactor in the sky. Second is the sparkling of long lived heavy isotopes generated via cataclysmic supernova nucleosynthesis occurring about the time our sun first began to glow, before it became a sun, suffused through Earth's core and mantle. The third is gravitational friction from lunar and solar tides. Our fossil fuels, coal and oil, were formed via sequestration of carbon concentrated through biological activity powered by solar nuclear activity three hundred million years ago, largely during the Permian and Carboniferous epochs.
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