Lisias Posted January 5 Share Posted January 5 6 hours ago, AckSed said: First 'proper' pooper? The first space toilet was on Skylab, so the first one would have been one out of Pete Conrad, Joseph P. Kerwin or Paul J. Weitz of SkyLab 2. This probably meant to space-faring what the latrine meant to civilization! "A small fart for a man, a huge..." uh... Never mind. Quote Link to comment Share on other sites More sharing options...
softweir Posted January 5 Share Posted January 5 15 hours ago, AckSed said: Apparently, farts ... But surely the Isp of low-mass, low-velocity methane would have been far too low to create any significant dV? Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted January 5 Share Posted January 5 46 minutes ago, softweir said: But surely the Isp of low-mass, low-velocity methane would have been far too low to create any significant dV? In microgravity, any impulse will cause an acceleration, however small… Quote Link to comment Share on other sites More sharing options...
magnemoe Posted January 5 Share Posted January 5 1 hour ago, StrandedonEarth said: In microgravity, any impulse will cause an acceleration, however small… Who is true but I think that moving the legs pressing one the seat would have an far larger effect. You want an decent airflow into an space toilet to do the work of gravity sucking everything in. Quote Link to comment Share on other sites More sharing options...
Lisias Posted January 5 Share Posted January 5 (edited) 2 hours ago, softweir said: But surely the Isp of low-mass, low-velocity methane would have been far too low to create any significant dV? You, surely, never tasted Brazilian Feijoada. 1 hour ago, StrandedonEarth said: In microgravity, any impulse will cause an acceleration, however small… Jesus Christ... I gogglo'ed this just for the LULz and ended up finding... Something... Quote (PDF) Innovative Solid Rocket Propellant Formulations for Space ... Academia.edu https://www.academia.edu › Innovative_Solid_Rocket_... Innovative Solid Rocket Propellant Formulations for Space Propulsion ... Innovative Solid Rocket Propellant Formulations for Space Propulsion ... sauerkraut · Erni ... (emphasis are mine) ==== EDIT ==== It was a SEO SCAM, I downloaded the damned PDF and there's nothing remotely near that. Edited January 5 by Lisias it was a scam Quote Link to comment Share on other sites More sharing options...
darthgently Posted January 5 Share Posted January 5 16 minutes ago, Lisias said: It was a SEO SCAM, I downloaded the damned PDF and there's nothing remotely near that Thanks for taking one for the team and the warning! Quote Link to comment Share on other sites More sharing options...
Lisias Posted January 7 Share Posted January 7 (edited) As a matter of fact, I just discovered that nope, we can't detect this hypothetical modulation on Gravitational Waves (of course, if this thing will ever exist). Yet. However, there's a theoretical phenomena called Gravitational Wave Memory and Scientists are going to research if this thingy really exists. TL;DR: when a GW propagates into spacetime, every matter it traverses changes the spacetime a tiny little bit in a way that could allow someone to infer when and where this happened (since the name "Memory"). Such "memory prints" would be extremely small, smaller than an atom, but it may be possible to detect them (if they exist) using an experiment to be launched in 2035, the LISA. If this GWM thingy exists, and can be detected (some speculations suggest that some could be detected using current technology, by the way), then it would be possible to detect modulations on it too**. ====================================== **EDIT: NOPE! While the oscillatory part of the merger gravitational waveform will be outside the frequency sensitivity range of pulsar timing arrays, the nonoscillatory GW memory effect is detectable. https://ntrs.nasa.gov/citations/20210010596 Even by being able to detect GWM, we are still unable to detect the oscillations themselves, what to say about a hypothetical modulation ===================================== Interesting thought. On 12/16/2024 at 4:11 AM, Lisias said: Assuming a Civilization Level III on the Kardashev Scale would like, by reasons beyound our reasoning, transmit a message to the Universe. It's known that Light have a horizon that limits the reach of such message, not to mention the shift to red due the spacetime expansion. Yeah, I'm talking about the limits from the Observable Universe. But since Gravitational Waves are not particles traveling in the spacetime, they are the own spacetime compressing and expanding (waves). So such waves would not have the same limitation of Light, that reaches a point in which the spacetime length it's going to travel "stretches" faster than it's own speed. Gravitational Waves travel on the spacetime itself, so these waves ends up being stretched together the spacetime itself instead of staying behind. So, the best way to transmit a one way message to the rest of the Universe would be by modulating Gravitational Waves (how they would do it it's out of the scope of this thought experiment - they are a Level III and not us for a reason!). Would we, primitive beings stumbling each other on the 3rd rock from the local Star, be able to detect such modulation on Gravitational Waves? More on this video: Spoiler Edited January 10 by Lisias Correcting myself. (EDIT) Quote Link to comment Share on other sites More sharing options...
K^2 Posted January 9 Share Posted January 9 On 1/6/2025 at 5:25 PM, Lisias said: More on this video: Hide contents His videos are full of misinformation. Anton's background in astronomy is rather rudimentary, and in cosmology non-existent. He often brings up speculation about models that aren't just unconfirmed, but retracted, and does so without understanding any of the math that went into them in the first place. This particular video is a good example. Quote Link to comment Share on other sites More sharing options...
Lisias Posted January 10 Share Posted January 10 (edited) On 1/6/2025 at 10:25 PM, Lisias said: As a matter of fact, I just discovered that nope, we can't detect this hypothetical modulation on Gravitational Waves (of course, if this thing will ever exist). <yada yada yada> Probably due my (layman) researches about the subject, Youtube started to suggest to me more videos related to this subject. And one of them, boy oh boy, it's something pretty... interesting. In 2008 it was detected that some (observable) masses on the Observable Universe apparently are converging to a specific point beyound the Cosmological Horizon, like a huge concentration of mass had passed trough them in high speeds and added momentum to them due gravitational pull in the process (hypothesis A) - and since Momentum were added, Inertia kicked in and they kept moving faster. Or, perhaps, like a giganormous concentration of mass beyound the Horizon would be attracting them due gravity (hypothesis B). Problem: both hypothesis contradicts what we currently understand as how the Universe works! Hypothesis B is obvious: if Gravity is restricted to the Speed of Light, then anything beyound the Cosmological Horizon is unable to exert Gravity (or any kind of causality) in "our side" of the Horizon. Point. So or there's nothing there (so Hypothesis A), or Gravity can break the Ligtht Speed jail. So one could rest assured that Hypothesis A is the answer, right? Right? Problem: this would break the homogeneity and the isotropy of the Universe (i.e., the Universe has more or less the same mass and energy in all directions), literally destroying every single currently working models of the Universe. All our observations appears to confirm the Universe is uniform (homogeneous and isotropic), and so such a enormous concentration of mass in the very early stages of Cosmic Inflation would not be possible. So we are back to Hypothesis B. But, by then, what in God's Name is that giganourmous concentration of mass and from what deepness of Hell did it come from? And Gravity really can break the Light Speed jail, so? Ladies and Gentlemen, I present you Dark Flow: Quick visual explanation here (at t=312): Good thing I'm a software developer - it's not up to me so crack this nut! --- POST EDIT --- And since we are here... Gravitational wave memory is said to arise when a gravitational wave burst produces changes in a physical system that persist even after that wave has passed. This paper analyzes gravitational wave bursts in plane wave spacetimes, deriving memory effects on timelike and null geodesics, massless scalar fields, and massless spinning particles whose motion is described by the spin Hall equations. All associated memory effects are found to be characterized by four ``memory tensors,'' three of which are independent. These tensors form a scattering matrix for the transverse components of geodesics. https://arxiv.org/abs/2407.00174 And Gravitational wave memory is a nonoscillatory correction to the gravitational wave strain predicted by general relativity, which has yet to be detected. Within general relativity, its dominant component known as the null memory can be understood as arising from the backreaction of the energy carried by gravitational waves, and therefore, it corresponds to a direct manifestation of the nonlinearity of the theory. http://www.phy.olemiss.edu/StronGBaD/talks/Favata.pdf Oh, and from NASA: The mergers of supermassive black hole binaries (SMBHBs) promise to be incredible sources of gravitational waves (GWs). While the oscillatory part of the merger gravitational waveform will be outside the frequency sensitivity range of pulsar timing arrays, the nonoscillatory GW memory effect is detectable. Further, any burst of GWs will produce GW memory, making memory a useful probe of unmodeled exotic sources and new physics. https://ntrs.nasa.gov/citations/20210010596 And nope, I don't understand a thing from all of that. Edited January 10 by Lisias Post Edit Quote Link to comment Share on other sites More sharing options...
K^2 Posted January 10 Share Posted January 10 2 hours ago, Lisias said: In 2008 it was detected that some (observable) masses on the Observable Universe apparently are converging to a specific point beyound the Cosmological Horizon, like a huge concentration of mass had passed trough them in high speeds and added momentum to them due gravitational pull in the process (hypothesis A) - and since Momentum were added, Inertia kicked in and they kept moving faster. Or, perhaps, like a giganormous concentration of mass beyound the Horizon would be attracting them due gravity (hypothesis B). Problem: both hypothesis contradicts what we currently understand as how the Universe works! Hypothesis B is obvious: if Gravity is restricted to the Speed of Light, then anything beyound the Cosmological Horizon is unable to exert Gravity (or any kind of causality) in "our side" of the Horizon. Point. So or there's nothing there (so Hypothesis A), or Gravity can break the Ligtht Speed jail. So one could rest assured that Hypothesis A is the answer, right? Right? Problem: this would break the homogeneity and the isotropy of the Universe (i.e., the Universe has more or less the same mass and energy in all directions), literally destroying every single currently working models of the Universe. All our observations appears to confirm the Universe is uniform (homogeneous and isotropic), and so such a enormous concentration of mass in the very early stages of Cosmic Inflation would not be possible. So we are back to Hypothesis B. But, by then, what in God's Name is that giganourmous concentration of mass and from what deepness of Hell did it come from? And Gravity really can break the Light Speed jail, so? Ok, so first of all, you're 2 for 2 on YouTube channels I would strongly recommend avoiding. Astrum has a lot of the similar problems, where it takes sensationalist approach to an observation and runs with a hypothesis that's, to put it lightly, not seen as likely, and without any deeper understanding of cosmology involved. Secondly, you need to understand that any acceleration that we observe has to be explainable by matter within observable universe. Because we'd be observing it. Another way to look at it is noting that the path from gravity's source to us is at most as long as the sum of paths from source to observed mass flow and from there to us. (Worst case scenario, that is the shortest path.) Meaning, if the gravity's source is outside of our horizon, it can't produce acceleration detectable by us. However, it is very important to keep in mind that the earliest universe is opaque. What we call the observable universe is everything down to the age when it cleared, around 380ky after the big bang. Anything older than that is effectively obscured by the cosmic background. Because the universe is expanding at an accelerated rate, some galaxies that started out in that shell have moved beyond it since, making them invisible to us now. Meaning, there are masses we don't account for, and any random fluctuation anisotropy in them would be exacerbated by the higher density of the early universe. So if you naively compare the observable universe to movement of distant galaxies, there is an anomaly, that's trivially explained by the clusters and superstructure that goes just beyond, and are still falling within the normal distribution of densities consistent with the part of the universe we can observe. In simple, simple terms - if these galaxies were accelerating, it'd be weird. Movement is easily explained. In fact, if you simply started with the Wikipedia entry for Dark Flow, you would have discovered that a) evidence for it is inconclusive and somewhat controversial, and b) even if we were to assume it exists, the amount of flow consistent with measurements could be explained by density fluctuations in the early, opaque universe well within fluctuations allowed by the cosmic background radiation that we do observe. One paper puts the detection significance at 0.7 sigma. By the way, note the date. It's from 2009. As well as the original claim that the Astrum video talks about. Yes, there hasn't been anything new recently discovered. This is something that astronomers looked into more than a decade and a half ago, and there's been little change since, yet it's presented across several sensationalist pseudo-scientific channels as sensational new discovery. In other words, please, stop watching junk. If you want a recommendation on a good astronomy channel that goes over interesting discoveries and is done by somebody who is actually an active researcher, you can't go wrong with Dr. Becky. I would much rather you be legitimately confused by Hubble Tension than fall for that pseudo-scientific garbage. Quote Link to comment Share on other sites More sharing options...
Entropian Posted January 10 Share Posted January 10 The sheer number of channels posting this garbage in the quantities I see is highly concerning to me - a lot of young people these days consume media through places like YouTube and I can't help but worry that these kinds of things are poisoning the waters for future astrophysicists 10-20 years down the line. Quote Link to comment Share on other sites More sharing options...
farmerben Posted January 10 Share Posted January 10 It might be garbage, but a lot of the stuff I read back in the 90's and early 2000's was probably worse garbage. The observations of the past 30 years are incredible. But, I'm of the school that the best science predicts something before observing it. Some have it the other way round. Quote Link to comment Share on other sites More sharing options...
Lisias Posted January 10 Share Posted January 10 (edited) 6 hours ago, farmerben said: It might be garbage, but a lot of the stuff I read back in the 90's and early 2000's was probably worse garbage. . And at least we can double check them nowadays. 30 years ago there was absolutely no way to second guess anything written on a popular "science" magazine. Has anyone had read the 60s ones? We are WAY better nowadays. 14 hours ago, Entropian said: The sheer number of channels posting this garbage in the quantities I see is highly concerning to me Good thing we have the NASA guys to falsify their videos, right? Right? Distant galaxy clusters mysteriously stream at a million miles per hour along a path roughly centered on the southern constellations Centaurus and Hydra. A new study led by Alexander Kashlinsky at NASA’s Goddard Space Flight Center in Greenbelt, Md., tracks this collective motion – dubbed the “dark flow” – to twice the distance originally reported. “This is not something we set out to find, but we cannot make it go away,” Kashlinsky said. https://www.nasa.gov/news-release/mysterious-cosmic-dark-flow-tracked-deeper-into-universe/ Don't misunderstand the message with the messenger. Mon Dieu, c'est plein de Baobabs... Edited January 10 by Lisias brute force post merge Quote Link to comment Share on other sites More sharing options...
K^2 Posted January 11 Share Posted January 11 8 hours ago, Lisias said: Good thing we have the NASA guys to falsify their videos, right? Right? I'll let you figure out what the problem with referring to that article is based on this screenshot from it. Quote Link to comment Share on other sites More sharing options...
Kerbalsaurus Posted Sunday at 08:12 PM Share Posted Sunday at 08:12 PM What’s the difference between wheat and barley? Quote Link to comment Share on other sites More sharing options...
AckSed Posted Monday at 06:03 PM Share Posted Monday at 06:03 PM 20 hours ago, Kerbalsaurus said: What’s the difference between wheat and barley? Quite a few, so I'll cover some of the similarities first. Both are ancient, being cultivated as far back as 9000BC at least, both belong to the Triticeae family, and both were and are grown for beer and animal feed. Barley prefers growing in lower temperatures. Domesticated wheat has gluten, which helped the Egyptians make a more springy bread with the addition of yeast. Barley bread was and is a dense, gummy mouthful. Barley, in my part of the woods, makes for an essential addition to vegetable soup as a thickener. It has fair amounts of niacin and thiamine, though not as much as some wheats. Wheat has much more protein than barley, though it is not readily absorbed. It is also deficient in lysine, which means that it was often consumed with legumes (peas, beans, lentils). Wheat has a much more tangled family tree, being inbred and crossbred with other plants for drought resistance, suitability for bread and disease resistance. To this day, most of the barley humans use for food go into alcoholic drinks-making. Quote Link to comment Share on other sites More sharing options...
DareMightyThingsJPL Posted Monday at 09:56 PM Share Posted Monday at 09:56 PM Is there a difference between antimatter initiated, and antimatter catalyzed microfission/microfusion? I know the difference between fission and fusion, but was wondering why some engines used 'catalyzed', whilst others used 'initiated' in their names. Quote Link to comment Share on other sites More sharing options...
AckSed Posted Monday at 11:01 PM Share Posted Monday at 11:01 PM 55 minutes ago, DareMightyThingsJPL said: Is there a difference between antimatter initiated, and antimatter catalyzed microfission/microfusion? I know the difference between fission and fusion, but was wondering why some engines used 'catalyzed', whilst others used 'initiated' in their names. I think it means that "initiated" makes the nuclear reaction happen at all, and "catalysed" makes the nuclear chain-reaction happen. The difference is somewhat 'angels dancing on the head of a pin', but this page uses both: https://web.archive.org/web/20070103171724/http://www.engr.psu.edu/antimatter/documents.html Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted Tuesday at 12:39 AM Share Posted Tuesday at 12:39 AM If I get a job selling ice cream at KSC, can I tell people I'm a NASA employee? Quote Link to comment Share on other sites More sharing options...
DareMightyThingsJPL Posted Tuesday at 01:32 AM Share Posted Tuesday at 01:32 AM 2 hours ago, AckSed said: I think it means that "initiated" makes the nuclear reaction happen at all, and "catalysed" makes the nuclear chain-reaction happen. The difference is somewhat 'angels dancing on the head of a pin', but this page uses both: Thanks! Quote Link to comment Share on other sites More sharing options...
monophonic Posted Tuesday at 06:44 AM Share Posted Tuesday at 06:44 AM 6 hours ago, JoeSchmuckatelli said: If I get a job selling ice cream at KSC, can I tell people I'm a NASA employee? If your pay slip says NASA, then yes. If your pay slip says anything else, you are a consultant to NASA instead. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted Tuesday at 11:35 AM Share Posted Tuesday at 11:35 AM 4 hours ago, monophonic said: consultant I might need to get a badge made then! Hi - I'm Joe NASA Consultant *would you like nuts with that? " Quote Link to comment Share on other sites More sharing options...
DDE Posted Tuesday at 12:25 PM Share Posted Tuesday at 12:25 PM 49 minutes ago, JoeSchmuckatelli said: I might need to get a badge made then! Hi - I'm Joe NASA Consultant *would you like nuts with that? " No, that's a... *breathes in* delivery expert. Sincerely, a consultant. Quote Link to comment Share on other sites More sharing options...
K^2 Posted Tuesday at 05:48 PM Share Posted Tuesday at 05:48 PM 10 hours ago, monophonic said: If your pay slip says anything else, you are a consultant to NASA instead. "Contractor working at <place>" is the standard phrasing. We have a lot of "Contractor v. FTE" (Full Time Employee) discussions around here in the Valley. If your resume lists FAANG (MAANA????) it makes a huge difference if it's a "worked at" vs "worked for". Personally, I think it's ridiculous, because these people are doing literally the same job most of the time, but I have a lot of empirical evidence for it making a huge impact on your ability to find jobs in the future. Being an FTE in one of these automatically passes you on a pre-screen and sometimes the first round of interviews. Quote Link to comment Share on other sites More sharing options...
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