Lawnmower Boy Posted February 11, 2016 Report Share Posted February 11, 2016 Yeah, the evidence looks quite convincing for detection of gravitational waves from a black hole merger, detected last September 14. A 29 solar mass black hole merged with a 36 solar mass black hole, about 1.3 billion years ago (i.e., 1.3 billion light years away), forming a 62 solar mass single black hole. 3 solar masses was converted into gravitational waves energy and radiated away over about 20 milliseconds. Public Authority: "Evacuate now! Get in your spaceships and get to warp right now! Leave everything that can't run to the launch pads! Fly, you fools!" Radio News One: "And now for a counterpoint, a representative of the Real Estate Board of Omnicron Aurigae Beta VII." Real Estate Guy: "Thanks, Chet. I just want to say that that's crazy talk. Yes, three solar masses of gravitational waves will be a tad bumpy. But consider the one million percent increase in sale prices of single family detached residences in the greater metropolitan Omnicron Aurigae Beta VII area over the last solar period. A mere cosmos-scale gravitational radiation wave event isn't going to effect the fundamentals of this upside market. Yes, prices will cool off due to the billion trillion electron volt radiation impingement, but spontaneous collision-derived ground level uncontrolled fusion events are mainly a concern for structures built before the modern building codes were brought in. " Public Authority: "Are you, are you insane? Everyone who is on this planet in an hour is going to be reduced to hot plasma! Along with their granite countertops!" Radio News One: "Please, sir, there's no call to be uncivil here. It's a discussion, not a name-calling contest." Real Estate Guy: "Oh, indeed, Chet. Remember that with real estate, the key point is that they're not making any more of it. Our projections of future population growth, based on the reasonable assumptions that we will soon learn to cure entropy and reproduce by spontaneous mitosis, shows population here on Omnicron Aurigae Beta VII rising by one billion percent in the next solar period. Well, that's if our sun isn't blown into supernova, but how likely is that? Only somewhat likely. The million percent increase in housing prices over the last period is going to seem positively infinitesmal compared with the increase in the next. Sell now! Buy nower! Wait a second. I've got to take a call. Business." Radio News One: "Wait. If prices are going to keep going up, why does everyone need to sell now? For clarification, this station turns to the Public Authority. Oh, wait, the Public Authority has just taken off in their spaceship, saying something about trying to make the escape run in less than twelve parsecs. Do you have a comment, Real Estate Guy? Real Estate Guy? Oh. There goes his ship. I . . . Oh, crap. Honey? Yeah, I know we just closed the deal on the house, but I think we maybe should think about staying with my sister over on Gamma Fomolhaut . . . Sorry, hon, you're breaking up. Too much interference. . . . " Quote Link to comment Share on other sites More sharing options...
DShomshak Posted February 11, 2016 Report Share Posted February 11, 2016 It's a nice centennial present for General Relativity and another win for Einstein. (And, incidentally, reminds me why I've become a bit, well, impatient with the String Theory crowd. Thirty years of work and, last I heard, still no testable predictions?) Dean Shomshak Quote Link to comment Share on other sites More sharing options...
Lucius Posted February 12, 2016 Report Share Posted February 12, 2016 Yeah, the evidence looks quite convincing for detection of gravitational waves from a black hole merger, detected last September 14. A 29 solar mass black hole merged with a 36 solar mass black hole, about 1.3 billion years ago (i.e., 1.3 billion light years away), forming a 62 solar mass single black hole. 3 solar masses was converted into gravitational waves energy and radiated away over about 20 milliseconds. ... Three solar masses worth of gravity waves? That can't be healthy! In the immediate vicinity, it surely wasn't. 1.3 billion light-years away, we can be more blase. Sometimes I think Drake and Fermi were asking the wrong question. Given the sheer number of things I hear about that are capable of destroying or sterilizing entire solar systems maybe the question isn't "Where is everybody?" but "How are we still standing?" Lucius Alexander The palindromedary wonders how many potentially civilization-destroying disasters are possible that we don't even know about yet. Quote Link to comment Share on other sites More sharing options...
Christopher Posted February 12, 2016 Report Share Posted February 12, 2016 Sometimes I think Drake and Fermi were asking the wrong question. Given the sheer number of things I hear about that are capable of destroying or sterilizing entire solar systems maybe the question isn't "Where is everybody?" but "How are we still standing?" Lucius Alexander The palindromedary wonders how many potentially civilization-destroying disasters are possible that we don't even know about yet. It only takes about a million years to colonise the entire universe, once you got of your planet/home system. Without using any FTL drives. Our species is two million years old. Not including all the intermediate species we went through. Once you do get of your home system a mere "planetary annihilation" event can't kill your species anymore. A black hole colission is able to kill a few lightyears worth of civilisations, but black holes of that magnitude are not exactly common. Or hard to see when you are closer. If there was a species a mere 1000 years more advanced then ours nearby, they could have out-walked that. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted February 19, 2016 Author Report Share Posted February 19, 2016 NASA simulates growing potatoes on Mars in Peru Branson's Virgin Galactic moves to return to the Space Race Quote Link to comment Share on other sites More sharing options...
tkdguy Posted February 19, 2016 Author Report Share Posted February 19, 2016 Trash Day Aboard the ISS Quote Link to comment Share on other sites More sharing options...
tkdguy Posted February 23, 2016 Author Report Share Posted February 23, 2016 Do you hear music? Christopher 1 Quote Link to comment Share on other sites More sharing options...
Old Man Posted February 25, 2016 Report Share Posted February 25, 2016 SpaceX was scheduled to attempt a GEO launch today with an attempted first stage landing on a drone barge 400 miles downrange. That launch has been postponed until 630pm EST Thursday. Apparently this is a reused first stage, the one that successfully returned to the launch site a couple of months ago. Though they will attempt to recover the stage again, they're not really expecting it to work--the geosynchronous launch requires a longer burn, so the stage will have much less fuel reserves to work with. That's also why the landing attempt will be offshore; there is no way the booster would have enough fuel to make it back to solid ground. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted February 25, 2016 Author Report Share Posted February 25, 2016 Astronaut Scott Kelly believes travel to Mars is "clearly doable." Fireball streaks through atmosphere; almost nobody noticed Quote Link to comment Share on other sites More sharing options...
Cancer Posted February 25, 2016 Report Share Posted February 25, 2016 More AAS Nova links. Quick astrophysics fallout from the gravity-wave detection event Yes, there are systematic differences in luminosity for Type Ia supernovae, probably Disintegrating planets orbiting white dwarf have changed noticeably in the year since discovery tkdguy and Christopher 2 Quote Link to comment Share on other sites More sharing options...
DShomshak Posted February 26, 2016 Report Share Posted February 26, 2016 Yes, there are systematic differences in luminosity for Type Ia supernovae, probably A-Ha! I've wondered about this, since the whole claim of Dark Energy and accelerating expansion seems to rest on supernova-derived distance measurements. Not that I could imagine why there might be secular changes in supernova brightness: It's just that the claim of accelerating expansion is so extraordinary that every possible confounding factor should be checked. I can't see which way these results would affect the Dark Energy claim, but I'm glad to see someone's checking. Dean Shomshak Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted February 27, 2016 Report Share Posted February 27, 2016 I've been idly speculating in whether the metallicity of the star has anything to do with it. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted March 2, 2016 Author Report Share Posted March 2, 2016 Coming home Quote Link to comment Share on other sites More sharing options...
Cancer Posted March 2, 2016 Report Share Posted March 2, 2016 A-Ha! I've wondered about this, since the whole claim of Dark Energy and accelerating expansion seems to rest on supernova-derived distance measurements. Not that I could imagine why there might be secular changes in supernova brightness: It's just that the claim of accelerating expansion is so extraordinary that every possible confounding factor should be checked. I can't see which way these results would affect the Dark Energy claim, but I'm glad to see someone's checking. Dean Shomshak I've been idly speculating in whether the metallicity of the star has anything to do with it. Yeah, that latter is the chief suspicion. If low-metallicity stellar evolution gives you white dwarfs that are systematically different from ones resulting from higher metallicity stellar evolution, then the energy yield might be different between the two if they explode. And with the look-back time, the more distant SNe will be from generally metal-poor environments, since metals accumulate over time. I do not know enough about the physics of degenerate-dwarf supernovae to have an opinion about that: the details really matter and it has been a while since I kept up on the supernova literature. DShomshak 1 Quote Link to comment Share on other sites More sharing options...
DShomshak Posted March 3, 2016 Report Share Posted March 3, 2016 On other matters, has anyone else heard about the quasar that apparently shut down sometime in the last few years? I heard the story last week on BBC Radio, interviewing one of the astronomers. The team looked again at a quasar they'd studied several years ago, and it wasn't there anymore. As the astronomer said, there's nothing physically impossible about this: If quasars are indeed the light of superheated gas spiraling into supermassive black holes, well, this black hole just ran out of gas. But it's unusual to see something change so dramatically in such a short time. Dean Shomshak Quote Link to comment Share on other sites More sharing options...
tkdguy Posted March 4, 2016 Author Report Share Posted March 4, 2016 Extragalactic radio bursts detected Scott Kelly grew 2 inches in space Quote Link to comment Share on other sites More sharing options...
Christopher Posted March 4, 2016 Report Share Posted March 4, 2016 Scott Kelly grew 2 inches in space So what if we send the Grinch into space? Would his heart grow 3 sizes without the ephiphany of the story? Quote Link to comment Share on other sites More sharing options...
DShomshak Posted March 4, 2016 Report Share Posted March 4, 2016 As luck would have it, the latest Scientific American has an article about dark energy; the writers include one of the astronomers involved in the original studies that discovered the apparent accelerating expansion. The article laid out the pros and cons of three proposed explanations: the Cosmological constant (a.k.a. vacuum energy), Quintessence, and Modified Gravity. Didn't mention the possibility of secular changes in supernova brightness or other systematic errors, but otherwise it seemed quite fair in laying out the arguments for and against -- mostly, the authors ruefully admit, against. Dean Shomshak Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted March 5, 2016 Report Share Posted March 5, 2016 It would simplify things if Dark Energy wasn't around ... Quote Link to comment Share on other sites More sharing options...
dmjalund Posted March 5, 2016 Report Share Posted March 5, 2016 It would simplify things if Dark Energy wasn't around ... but my supervillain depends on dark energy to conquer the world! Quote Link to comment Share on other sites More sharing options...
Christopher Posted March 5, 2016 Report Share Posted March 5, 2016 It would simplify things if Dark Energy wasn't around ... To quote Captain Kirk in the Game Star Trek Academy: "That would be a simple solution. But if you want simple solutions, you are in the wrong place." It would be nice if for once the universe answers a question without raising 15 new ones. But it's track record speaks against that. Quote Link to comment Share on other sites More sharing options...
Old Man Posted March 5, 2016 Report Share Posted March 5, 2016 It's toying with us. The way a cat toys with its food. Quote Link to comment Share on other sites More sharing options...
Cancer Posted March 9, 2016 Report Share Posted March 9, 2016 And after it tries eating us, we'll come back up like a hairball. I'm sure this is in someone's cosmological model somewhere. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted March 9, 2016 Report Share Posted March 9, 2016 Probably some Mesoamerican religion. Quote Link to comment Share on other sites More sharing options...
DShomshak Posted March 12, 2016 Report Share Posted March 12, 2016 Well, not every great discovery pans out; or it turns out that one discovered something different. This month's Scientific American also has a short article about Big Rocks from Space as the cause of mass extinctions. In brief, the theory is dead. Of the 5 biggest mass extinctions in the fossil record, 4 are associated with massive flood basalt events. As geologists have refined the dates, the association has become tighter and tighter. Only the K-T extinction had a Big Rock From Space impact, but the Deccan Traps eruption was happening at the time and appears to have been plenty big enough to kill off the dinosaurs (and a whole lot more) all by itself. No impacts have been found at the times of other mass extinctions, so it looks like the Chicxulub impact was just a coincidence. (Granted, a big rock falling on a bed of sulfur-rich limestone probably made things worse. K-T impactor co-discoverer Walter Alvarez also tries to keep the theory alive by arguing that the impact shook the Deccan eruption fissures wider, making it worse. Maybe so, but it now looks like the impact was only an aggravating factor, not the main cause.) The Big Rock From Space hypothesis wasn't worthless. It got geologists looking at rock strata and fossil evidence in new ways. It was wrong, but productively wrong, which makes it a good example of science operating as it should. Also, the Ordovician mass extinction remains mysterious. No Big Rock From Space; no Large Igneous Province. Dark Energy may turn out to be another case where the apparent discovery turns out not to be the real discovery. It may take a few decades to figure it out, though. Dean Shomshak Hyper-Man 1 Quote Link to comment Share on other sites More sharing options...
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