Cancer Posted October 17, 2017 Report Share Posted October 17, 2017 No, gravitational waves propagate at the speed of light. That is actually a part of the direction-finding for the events in the sky: the observatory on the side of Earth closer to the wavemaking event detects it earlier than the others, by interval = (difference in distance along direction to event)/(speed of light). EDIT: In this case, the VIRGO instrument in Italy detected it first, followed 22 milliseconds later by LIGO in Louisiana, followed 3 milliseconds later by LIGO at Hanford. For the neutron star merger announced yesterday, the interval between GW arrival and onset of the light flash is due to the time needed for the hot ejecta to expand to a big enough volume to be detectable by telescopes 40 megaparsecs away. EDIT: Figure 2 here shows the sequence of detections in various means, though it takes some work to grasp everything in that figure. Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 18, 2017 Report Share Posted October 18, 2017 How spacecrafts release wastewater could explain Enceladus' jets Wastewater flushed from manned spacecraft could help researchers better understand the icy plumes of water that erupt from the south pole of Saturn's moon Enceladus, according to findings presented at a meeting of the American Astronomical Society's Division for Planetary Sciences. "These observations don't tell us directly what's happening on Enceladus, but they provide a sort of anchor for our interpretations of what we're seeing on Enceladus," presenter Ralph Lorenz said. [tongue in cheek] So Enceladus is a spacecraft and we're watching it dump sewage. Hmmmm. [/tongue in cheek] Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted October 18, 2017 Report Share Posted October 18, 2017 I saw somewhere that VIRGO never saw the signal; that it came in its blind spot. Can that be right? Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 18, 2017 Report Share Posted October 18, 2017 [tongue in cheek] So Enceladus is a spacecraft and we're watching it dump sewage. Hmmmm. [/tongue in cheek] What are the chances the Milennium Falcon will come out "with the rest of the trash"? Quote Link to comment Share on other sites More sharing options...
pinecone Posted October 18, 2017 Report Share Posted October 18, 2017 Wait, something here is not right: Gravity waves are supposedly travelling instantly, not adhering to the light speed limit. The event was 100 million lightyears away So the time between us noticing the event via Gravity Observation and seeing anything with all our optical telescopes, should be literally 100 million years (+/- expansion of the universe). I Think the issue you're having is that Gravity is thought to be instant, ie if I create/move mass here the whole universe notes that, but gravity waves are waves, so they behave the way waves do....though the instant notation may be outdated. I am way out of touch with current physics. Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 19, 2017 Report Share Posted October 19, 2017 No, gravitational waves propagate at the speed of light. That is actually a part of the direction-finding for the events in the sky: the observatory on the side of Earth closer to the wavemaking event detects it earlier than the others, by interval = (difference in distance along direction to event)/(speed of light). EDIT: In this case, the VIRGO instrument in Italy detected it first, followed 22 milliseconds later by LIGO in Louisiana, followed 3 milliseconds later by LIGO at Hanford. For the neutron star merger announced yesterday, the interval between GW arrival and onset of the light flash is due to the time needed for the hot ejecta to expand to a big enough volume to be detectable by telescopes 40 megaparsecs away. EDIT: Figure 2 here shows the sequence of detections in various means, though it takes some work to grasp everything in that figure. I Think the issue you're having is that Gravity is thought to be instant, ie if I create/move mass here the whole universe notes that, but gravity waves are waves, so they behave the way waves do....though the instant notation may be outdated. I am way out of touch with current physics. I just read Wikipedia a bit. Apparently it was asumed to have infinite speed back in Newtonian Physics. But general relativity predcits speed of light. And chineses scientists found proof for this, using the moon and tides. Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 19, 2017 Report Share Posted October 19, 2017 Well, given that the core idea that gives rise to gravity waves is relativity, and a fundamental premise of relativity is that all frames of reference observe the same value for the speed of light, gravity waves have to propagate at the speed of light. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted October 19, 2017 Report Share Posted October 19, 2017 The fun part about that is, if there's a hypernova or gamma ray burst that wipes us out, our doom was preordained, in a manner of speaking, because the event that caused it will have happened years earlier. Quote Link to comment Share on other sites More sharing options...
DShomshak Posted October 19, 2017 Report Share Posted October 19, 2017 Actually, this has me thinking: The cosmic speed limit is the speed of light in a vacuum. The actual speed of light drops slightly if it's not in a vacuum. Intergalactic space is really, really close to a perfect vacuum... but not quite. Now I wonder if the gamma pulse (I would guess that's the light from the actual moment of collision) arrived very slightly later than the gravity waves, because space isn't entirely empty. I also wonder to what extent gravity waves behave like other waves. Is a gravity wave bent by the curved space of a gravitational field? Can they be diffracted? (By what?) It's like having a new toy. Makes me wish I were a physicist. Dean Shomshak Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted October 19, 2017 Report Share Posted October 19, 2017 How to construct a gravitational lattice...? Quote Link to comment Share on other sites More sharing options...
Lucius Posted October 20, 2017 Report Share Posted October 20, 2017 I also wonder to what extent gravity waves behave like other waves. Is a gravity wave bent by the curved space of a gravitational field? Can they be diffracted? (By what?) Can they be REfracted? If so, do you get Gravity's Rainbow? Lucius Alexander The palindromedary says astronomers have already detected the pot of gold... Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 20, 2017 Report Share Posted October 20, 2017 Actually, this has me thinking: The cosmic speed limit is the speed of light in a vacuum. The actual speed of light drops slightly if it's not in a vacuum. Intergalactic space is really, really close to a perfect vacuum... but not quite. Now I wonder if the gamma pulse (I would guess that's the light from the actual moment of collision) arrived very slightly later than the gravity waves, because space isn't entirely empty. I also wonder to what extent gravity waves behave like other waves. Is a gravity wave bent by the curved space of a gravitational field? Can they be diffracted? (By what?) It's like having a new toy. Makes me wish I were a physicist. Dean Shomshak The hard part is measuring that kind of stuff. Being unable to produce gravity waves ourself makes it really hard to figure out how they behave in a controleld enviroment. What confirmed relativity back in the day, was how starlight managed to "get around" a Eclipsed Sun. And that only works if gravity waves can not simply pass "through" all mater. Quote Link to comment Share on other sites More sharing options...
pinecone Posted October 20, 2017 Report Share Posted October 20, 2017 Yeah, I reacon if somebody wanted to you could set up a gravity wave expirament in space so you could occult the source with a star or pulsar and get readings...then do some math. Looking for interferance etc... Quote Link to comment Share on other sites More sharing options...
tkdguy Posted October 21, 2017 Author Report Share Posted October 21, 2017 How scientists predict if a spacecraft will fall and kill you Did the moon once have an atmosphere? Quote Link to comment Share on other sites More sharing options...
Tech priest support Posted October 28, 2017 Report Share Posted October 28, 2017 https://www.eurekalert.org/pub_releases/2017-10/tcd-wom102617.php#.WfM4_Yzpy2U.facebook Quote Link to comment Share on other sites More sharing options...
DShomshak Posted November 7, 2017 Report Share Posted November 7, 2017 The Nov. 4, 2017 issue of the Economist has two articles on interstellar travelers. The first is about asteroid A/2017 U1, whose trajectory showed that it came from outside the Solar System and is returning to interstellar space. The article incidentally notes that it has not been named yet, and suggests that "Rama" is available and would be appropriate -- after Arthur C. Clarke's novel, Rendezvous with Rama. The second is about proposals to include living organisms on the first interstellar probes. Some organisms, such as the nematode C. elegans, or the tardigrade, can provably survive 20+ years freeze-dried. So, put a few in the CD-sized, laser-propelled probes to Alpha Centauri and see if they can be revived at the end of the journey. Dean Shomshak pinecone 1 Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 8, 2017 Author Report Share Posted November 8, 2017 Any links on those? Quote Link to comment Share on other sites More sharing options...
Christopher Posted November 8, 2017 Report Share Posted November 8, 2017 15 hours ago, DShomshak said: The Nov. 4, 2017 issue of the Economist has two articles on interstellar travelers. The first is about asteroid A/2017 U1, whose trajectory showed that it came from outside the Solar System and is returning to interstellar space. The article incidentally notes that it has not been named yet, and suggests that "Rama" is available and would be appropriate -- after Arthur C. Clarke's novel, Rendezvous with Rama. When hearing Rama, I have to think about the Margarine. Sorry, just can not help myself: https://en.wikipedia.org/wiki/Rama_(food) 15 hours ago, DShomshak said: The second is about proposals to include living organisms on the first interstellar probes. Some organisms, such as the nematode C. elegans, or the tardigrade, can provably survive 20+ years freeze-dried. So, put a few in the CD-sized, laser-propelled probes to Alpha Centauri and see if they can be revived at the end of the journey So you want to expose a Tardigrade to Cosmic Radiation? There is that old joke/story that Apes send to space come back super-intelligent and Dogs might become Telepathic. In this case, we might be hoping to get the Spore Hub Drive from Discovery out of it Quote Link to comment Share on other sites More sharing options...
DShomshak Posted November 8, 2017 Report Share Posted November 8, 2017 7 hours ago, Christopher said: When hearing Rama, I have to think about the Margarine. Sorry, just can not help myself: https://en.wikipedia.org/wiki/Rama_(food) Well, it gives "Rendezvous with Rama" a somewhat, um, kinkier interpretation. Dean Shomshak Quote Link to comment Share on other sites More sharing options...
DShomshak Posted November 8, 2017 Report Share Posted November 8, 2017 12 hours ago, tkdguy said: Any links on those? The first visitor from another solar system has just ... - The Economist The first voyager to another star may be a worm or a tardigrade - Worm ... tkdguy 1 Quote Link to comment Share on other sites More sharing options...
Lord Liaden Posted November 9, 2017 Report Share Posted November 9, 2017 If a preserved organism in a probe we send crashes into another life-bearing planet, we might be responsible for a devastating plague or infestation. Granted, the chances are extremely remote, but still. (It would make for a cool sci-fi story, though.) Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted November 9, 2017 Report Share Posted November 9, 2017 The Revenge of the Tardigrades, sort of thing. Quote Link to comment Share on other sites More sharing options...
Christopher Posted November 9, 2017 Report Share Posted November 9, 2017 10 hours ago, Lord Liaden said: If a preserved organism in a probe we send crashes into another life-bearing planet, we might be responsible for a devastating plague or infestation. Granted, the chances are extremely remote, but still. (It would make for a cool sci-fi story, though.) In the Tiberium Wars reality of Command and Conquer for a long time it was not clear how the Tiberium first got onto the planet. I do not think the goal is to get them down onto the planet. Just see if even those beings can survive the journey. If something like a Tardigrade can not survive interstellar spaceflight that way, we might have 0 chance ourself. Quote Link to comment Share on other sites More sharing options...
Christopher Posted November 9, 2017 Report Share Posted November 9, 2017 A Zombie Star (original posted on teh other news Thread): http://www.bbc.com/news/science-environment-41916738 DShomshak 1 Quote Link to comment Share on other sites More sharing options...
DShomshak Posted November 10, 2017 Report Share Posted November 10, 2017 20 hours ago, Lord Liaden said: If a preserved organism in a probe we send crashes into another life-bearing planet, we might be responsible for a devastating plague or infestation. Granted, the chances are extremely remote, but still. (It would make for a cool sci-fi story, though.) As the article notes, the probe would be moving so fast that the crash would create an explosion of nuclear intensity. Nothing could survive that! (Except maybe a cosmically-irradiated tardigrade-turned kaiju.) Dean Shomshak L. Marcus 1 Quote Link to comment Share on other sites More sharing options...
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