Diche Bach

Isp means specific impulse, basically the efficiency of an engine. Thrust is the force the engine produces. Pretty sure, the more powerful engines tend to have lower Isp because they achieve greater thrust (assuming the same chemical fuel) largely by burning the fuel more rapidly compared to less powerful engines. There are probably clever mechanical ways to maximize efficiency (e.g., by shaping the exhaust or something like that) but for any given fuel there are inherent limitations on how efficient you can make an engine. At least that is my understanding at this point! Will be good to see if the local physicists and engineers give me a passing grade

Not to sound . . . disbelieving or even necessarily skeptical, but . . . every time I read something about elementary particle physics and the standard model, something about the seemingly flippant and almost facetious tone starts to make me feel like I'm reading a Lewis Carroll story. I think you brainiac physicists who actually understand this stuff get just a tad bit of fun from making it all a bit whimsical

Get the pod! Get the pod!

Somewhat unrelated thing I ran across the other day. Supposedly the core of the sun is not so much energetic like a 'nuclear bomb' but rather a compost heap!? Does this sound right to you guys?

Well I wish them the best of luck. When they succeed in a few years time, you can come back and tell me you told me so

It is a wonderful community

I don't want to belabor this and I do not hold any hope of convincing you of anything. But I thought other folks might find this interesting. Radiation risks for Mars astronauts. Spending a few months onboard ISS is one thing. Living the remainder of your life on Mars, or worse being conceived and born there is another thing entirely.

Le sigh . . . Believe me dude, I would love to believe that humans living on Mars, much less getting there, was something I might see in my lifetime. But unless I discount the obstacles, both technical and economic, I am unable to go with that wishful thinking that we both share.

Disputed. Perhaps one of the resident experts can clarify. Even to the extent that Earth's atmosphere does protect the surface from radiation, the fact that Mar's atmosphere is about 0.6% as dense on average indicates that the Martian atmosphere is unlikely to diminish much of the radiation at the surface as compared to in orbit.

Yes, the radiation on Mars is so mild that the MARIE experiment broke after a couple of powerful solar flares in 2003 Humanity is unlikely to ever go extinct, under any circumstances short of the ultimate fate of Earth being consumed by the Sun, some billion years hence. Nuclear war, asteroid impact, plagues, wars; as someone who has studied the evolutionary and cultural history of humans in all our diversity for over 30 years, I have no fear that any of such cataclysms have any reasonable prospect of driving humanity into "extinction." There is a strangely contradictory logic in arguing that (a) we have the ability, resourcefulness, and adaptability to colonize an inhospitable hellhole like Mars; yet ( we are simultaneously vulnerable to extinction because some fearful cataclysmic event might make Earth difficult to live on.

Uhhh . . . that sounds absolutely insane. Somebody has been reading too much Kim Stanley Robinson. First of all, there is the issue of the radiation. Forgive me for not remembering the exact figures, but if memory serves, anyone spending any long duration on the surface of Mars would be rendered sterile and at higher risk for various cancers. Not the type of place for tens of thousands of people to setup residence. The standard Sci Fi response to this is to setup vast underground residences to protect from the radiation. Couple of responses to this: anyone who has not lived in such a residence for an extended period has no business postulating it. In sum, if you want to propose building an underground base on Mars to house 10,000 people, first thing you ought to do is simply demonstrate that a community of even just 100 people can survive and thrive in an analogous underground structure in a harsh setting on Earth. Someplace in the remote Mongolian highlands might suffice, or else someplace like Novaya Zemlya. Even this would be a poor comparison because the 'colonists' in simulated Mars colony in a harsh environment on Earth would always know (as do Antarctic research teams) that their tour of duty is soon to be over and that it is possible to get help in the event of an emergency. Not to mention the gravity, air, radation, circadian cycles all being different. Apart from the radiation, what else is a problem with humans living for even a short period of time on Mars? Well, lack of large quantities of water or at minimum obstacles and problems with acquiring water. Yes I know that there is water there, but the mere presence of water, even large quantities of it, does not mean that it will be easy to acquire and use. Breathable air is another major issue, though that is probably more readily addressed given the abundance of carbon dioxide in the atmosphere. Obviously any long-term human presence on Mars is likely to require establishment of some sort of agriculture which I'm sure is doable even with current technology, but obviously much MUCH more constrained and risky than it might seem. One minor technical glitch ala Challenger disaster O-ring and you could very easily have starvation to deal with. Lastly is the issue of gravity. I shudder to imagine the harm that will be caused to people living in that sort of low gravity for prolonged periods. Eventually, we may conclusively have the technology to address each and all of these issues without question or concern. However, even then, what exactly is the point of people living on Mars? If the technology were rock solid, the economics were favorable and the obvious scientific missions were the focus, I can definitely see how some research outposts on Mars would be quite useful for myriad reasons. But 10,000 "colonists!?" That is quite simply insane. I have my doubts that we will _ever_ colonize Mars, but if we do it is likely to be 10,000 years in the future. Drawing an analogy between the Age of Discovery and European colonization of the New World, Africa and Asia (or any major migratory even in human history) with the idea of humans colonizing extraterrestrial environments is faulty for a number of reasons. 1. Space and every other celestial body in the solar system cannot sustain human life without extensive artificial means, which are both technically complex, risky and costly. 2. The costs of building a caravel or noa and sending a boat load of dirty peasants with a couple of bourgeois ex-soldiers / adventurers as officers off for a long ocean voyage for a Monarch of the early 1500s is no where near the ballpark of sending even a small crew of highly trained astronauts and scientists into orbit, much less to other planets, and to say nothing of colonies. 3. Even accepting the limited utilty of the analogy: You've got to walk before you run. Long before the voyages of Magellanes around the Cape, long before Columbus' voyage to the West Indies, there were literally thousands of years of development of nautical technology. There had been steady progressive evolution in nautical technology for hundreds of years in the late middle ages and progressively more and more exploration and trade. The small innovations that had occurred in the decades preceding these watershed events were tiny by comparison to the huge amount of evolution in seaborne exploration and trade during the preceding centuries. Moreover, there were already extensive trade networks that extended substantial distances in every direction. Thousands of military and trade ships had been plying the waterways of Europe, the Meditteranean the coast of Africa and even around the African Cape of Good Hope for quite some distance. If memory serves, Portugese explorers had already managed to get to India via the African cape when Magellanes set out to find a shortcut (oh the irony!). In sum, by the time the era of European colonization to which you are drawing an analogy took place, the social and technological institutions that made this possible had already been firmly in place for centuries. To make the analogy more valid. With the discovery of flight we put our first boat in the water. The Apollo missions were the equivalent of the first oar driven single mast galley. The space shuttle a failed attempt to use a more efficient sail design. SpaceX's delivery of a load of cargo to the ISS the first merchant vessel to safely finish an ocean-going trade journey (say the equivalent of going from Athens to Alexandria). Arguing that we are ready to colonize other planets because we are at a watershed in history equivalent to the "Age of Discovery" is misleading I believe. Rather, we are in the early phases of the very first oceangoing exploration and trade and suggesting that we are ready to colonize other planets is like suggesting that the ancient Carthaginians could easily have colonized the New World had thus just been a bit more intrepid.

Interesting. Husband and wife inside an airtight can on a non-stop mission with "no shortcut's home" . . . sure, nothing could go wrong with this arrangement. Seriously though, what is the point? Why put two people up there in space for a couple years? Apart from being a test of human endurance, what exactly does it accomplish? I suppose that it would break many records and from a human standpoint it would provide insights into the rigors of long space journeys. But I would think that we already have plenty of insight into that from all the thousands of person hours in Mir, ISS, etc. Furthremore, what is the point of manned mission to Mars (particularly one way!!? THATS INSANE!) in the first place!? Its a barren, highly radiated, nearly vacuum of a dirt ball. I can see very little real reason humans would ever want to go there . . . or at least, very little reason to go there on a shoestring-budget/half-baked mission plan with no obvious objective other than to "get there." Probes? Sure! Send hundreds of the little buggers up there and gather all the data you can gather. In the meantime, developing the technology to economically put stuff into space in the first place, followed by development of a true SPACE STATION that will set the foundation for in-space construction and full-fledged research labs in space, followed by some sort of presence on or near the moon, seem to me to be far more useful, reasonable and practical motives than sending humans to Mars.

Awright I'm gonna just admit that my mind is a bit blown to learn that relativistic time dilation effects are being measured by freaking GPS devices. I have a GPS in my phone! The fact that its all relative simultaneously does and does not make sense. I guess that makes sense . . .

Evidently "Distant Worlds" has been mentioned a sum total of five times on these forums. On the one hand, this is surprising because it is the sort of game that a lot of you KSP fans would I think very much appreciate. On the other, this doesn't surprise me because Matrix Games is overall not well known among gamers, though their 'regulars' are quite a devoted community. Lots of older players, retired military, retired scientists and the like . . . In my opinion, Distant Worlds Shadows is the best 4x space game out there at this stage. (Note, you've got to install Distant Worlds, then DW Return of the Shakturi, then Legends then Shadows, so the total price tag for the fully expanded and up-to-date game is probably in the ballpark of $100). Matrix is a bit weird compared to other contemporary publishers. Mostly their games are VERY historical strategic or tactical war games that reflect hex-based strategy & tactics (S&T) boardgames. They are probably most famous for what is certainly one of the most complicated, intricate, detailed and accurate grand strategy games of all times War in the Pacific Admiral's Edition. They don't claim that this game represents _every_ ship, plane, dinghy, battalion, and radar shack which was involved in the Pacific War, but it comes damn close. The rule book is around 500 pages of bible print. I'm a pretty smart guy, and I have played S&T boardgames since High School. I had managed to get to the point where I truly understood all of the rules in the original War in the Pacific. I just lost steam with the newer one, but I may go back to it eventually. Not all of their games are that complicated and obsessed with historical accuracy and some of their games have a bit more of a Civ-like feel or even a Risk feel. For example Crown of Glory Emperor's Edition was a great unsung game that I had a lot of fun with a few Play-By-Email matches with half-dozen other geeks. Matrix staff and their fans are very nice folks, although they do tend to be fairly militarily oriented and among their forum-dwellers there is a good bit of the "Get off my lawn!" sentiment. They don't work with Steam at all (to their loss I think) and their games tend to be rather expensive (WiPAE is $80!). As noted, they are not widely known among gamers. But somehow, they seem to have done well. Their product line continues to grow every year and their forums are generally pretty active. This puts "Distant Worlds" game into perspective by showing that, it was a fairly unusual new direction for Matrix and I think the first time they had worked with the games developer, a New Zealand group called Code Force. The main developer "Elliot" is pretty active on their Matrix forums. I'm not sure if Code Force is only one guy, but it is clearly a small "indie" developer similar to Squad. Matrix's previous space games had been pretty simple and uninspiring, but it was clear when DW first came out that this was something special, something that honestly was trying to push the envelope a bit. For one thing the way it renders space as a continuous zoomable thing manages to convey more effectively than any other space game the vastness and great distances involved (although the scales and numbers are still waaayyy scaled down relative to reality). The graphics are clearly not the focus, rather the strategic dynamics, empire building, spacecraft engineering, fleet operations, and logistics for lack of a better term are what this game is all about. Exploration is a key element of the game, and I believe it is done more effectively in DW than in any other game I've encountered. The balance between technology, ship design, ship cost (build and maintenance), exploration and empire growth are exceptional in this game. You honestly 'feel' like you are stewarding a young interstellar empire as you play this game. The ship combat is very comparable to other 4X space games, and reminds me a good bit of GalCiv II, in sum, well-done and satisfying. Much like GalCiv II, designing your own ships is a fun part of the game and essential to have the most effective fleets. I had bought the original Distant Worlds in 2010 when I used to be more active on their forums (my avatar over there is Anthropoid) but for various reasons just didn't get into it. Main thing for me was the small fonts used in the UI were headache enducing on my big screen TV 'monitor.' That was three years ago and the game has been continuously updated and expanded since then. With the DW-Return of the Shakturi expansion came out later in 2010, Legends about a year after that, and then Shadows came out this spring. I only owned DW vanilla up till recently and it was certainly a fun and playable game, so buying only that one and giving it a whirl is certainly a viable option I think. However, I have now updated to the most recent complete set, and I have to say, it really has a finished and satisfying feel to it. Mainly I just wanted to give the game some visibility in this KSP community, which I think this longish note does fine. But if there is any interest, I'd be happy to do a Youtube video or two just to showcase the game!

Thanks for the suggestions guys. Can you believe it, the hand-me-down phone I inherited from my wife doesn't have an "SD card" in it!? What the heck is an SD card anyway!? I'll see if my old phone can still snap pics and use a hard connection to transfer it, else get our old Olympus recharged. MACHINES! They hate me! . . . I know what it is; all that caving gear I wore out over the years has conveyed to its mechanical brethren to never give me a break. Between the machines and the rodents, I'm surrounded.

Also known as Targeted marketing.

Mice infested my snowblower, including (the little bastitches) stuffing their bedding (somehow they got their hands on about a plastic shopping bag FULL of red YARN!?") under the fly wheel. I've dismantled it and called the manufacturer about a fly wheel puller and they tell me "There is not such a tool. The technique is to use a 'brass pick' and a rubber mallet and tap in the center to knock it loose." I seem to recall removing at least one fly wheel in my day and this technique is foreign to me. What I'm gathering here is that the wheel itself is more or less just 'stuck' on there (perhaps with some little notches that lock it into place) and by tapping on the dimple in the middle it causes the underlying mount to recess and the fly wheel to shift upward (opposite to the direction of the tapping force). I recounted this understanding to the lady and she said, yep that is right. When I asked about putting it back on there she said 'it is basically just pressure that holds it on.' Are any of you guys familiar with such an operation? Any advice or suggestions? What about this "brass pick" business!? I may have a socket driver that has a small blunt square end which might fit inside that dimple, but I have never heard of a 'brass pick." When I asked her about this she said "more like an ice pick" and I clarified that what they really seemed to be talking about was a "brash punch." Any idea why they would specify brass? With the amount of effort I'm putting into fixing this thing, I'm tempted to just move back to Atlanta; it would be simpler!

I thought "orbit" was a simple matter of having a velocity within a certain mathematically defined range at a particular altitude, specified by the parent bodies mass, gravity and diameter. As such, I would think the simplest way to measure it is simply altitude and speed. If you are within the velocity window for a given altitude, then you know you are in orbit! Right?

There are a ton, but here is my current set:

Advertising on myriad sites that used to have no advertising at all, examples: various email providers, Google, Youtube, various wikias, various gaming forums, etc., etc. I predict that in 5 years (or less) the Internet will be like watching TV was in the late 1980s (around the time I stopped watching TV altogether)--a mind-numbing cavalcade of very creative, head-turning advertising, interspersed with the occasional glimpse of whatever it is you were actually seeking to view. I think I might have watched a sum total of 40 hours of TV [not counting movies] since 1989, and 37 hours of that was when I was in a traveling on business and either did not have a laptop or did not have a game on a laptop that I wanted to play, so had no choice but to watch a hotel TV. There are still a few enclaves of true Internet left: sites like this, Wikipedia, a small number of diffuse special-interest sites. Other than that, the multi-nationals and 'entrepreneurs' continue their slow inexorable acquisition and shifting of the culture to suit their symbiotic parasitism with consumers. This actually makes me rather sad. A service like Youtube is rather exceptional. It allows the average Joe and Sally to be creative and it allows people of like interests to communicate and share. There is also a lot of history on Youtube, and one might even go so far as to say it is a sort of 'digital archive' of the late 20th century and even earlier. But instead of retaining those pure features it is of course, like all good things being overrun with advertising.

Incompetent trolling efforts.

Fascinating. This was the best I could find. After one quick read through I can't say it is crystal clear to me. Know of any better descriptions? The thing(s) that puzzles me is: 1) is "dark matter" just basically asteroids, planetoids, dust, and the like which is so low albedo and/or so far from a luminous object and doesn't produce any other form of measurable radiation and is therefore simply 'invisible' to our telescopes? Or is it something more special? 2) Obviously glass or other material through which photons can pass also bends light. Isn't it possible that the phenomenae responsible for gravity lensing of distant objects is behaving by refraction or reflection instead of actual mass? 3) Is mass-based gravity lensing of light something that has been directly measured in experiments, or is it simply something that has been inferred from things like the Hubble Deep Field? 4) Does mass-based gravity lensing apply to other forms of radiation? Can X-rays and gamma rays, etc., be bent? 5) It would seem to me, with my very naïve (but Oh so creative!) view of physical sciences, that, assuming that mass-based modification of light and/or other forms of radiation is a general and well-established phenomenon that it must have some rather profound engineering principles. Namely, if you can control energetic particles with nothing but mass, then it would seem you can potentially harness very large sources of energy for 'free' (meaning without having to expend energy. For example, for hypothetical cases, lets say we put together an object that was as massive as the Earth (I know, not gonna happen, but bear with the childlike imagining). I would think that if we could shape into a specific shape and position such an object where we wanted, we could effectively harness and intensity radiation from the sun in such a way to concentrate it for some useful purpose? Obviously, at the mega scale that is not going to happen. But if this mass-energy interaction effect extends downward in scale then perhaps it might really be a basis form something practical at the nano-technology scale? A device in which some ambient source(s) of radiation (for example bananas, or 'spent' nuclear fuel, etc.) is structured with matching sources of mass to concentrate/magnify and redirect the energy into useful behavior? ADDIT: Ah one last question! 6) Reading up about this on wiki a bit it sounds like there is at least one major assumption to thisweak gravitation lensing methodology: that the interstellar medium itself is not the source of the lensing. If the aggregation of many background objects is being used and estimates of the intervening mass are being derived from that, there are, if I'm not wrong, two interpretations: a) there is an intervening object of "Q" mass and X, Y, Z shape between us and those background objects, i.e., the assumption that seems to be typical. there are intervening object(s) of "Q" mass and effectively no shape between us and those background objects. What I mean by ( is: if light is traveling through several hundreds of millions or billions of light years of "empty" space (meaning space that does not have some sort of special "dark matter" in it) it would seem that it could nonetheless be bent by the diffuse matter and energy of the intergalactic medium? Because as we know the "empty" space in our solar system is not truly and completely empty. There are some atoms in the "vacuum" of the interplanetary medium (not to mention energetic particles), and it may be reasonable to postulate that there is also some matter and energy in the intergalactic medium? Assuming that is the case, wouldn't it be possible for the sum total of all that diffuse matter and or/energy past which the light from the background objects is moving to cumulatively bend it as if the light had instead passed an aggregation of "dark matter" of the same mass? . . . . Ahhh, now that I think this through a bit more I see that even if ( is the case, lensing is nonetheless revealing some sort of discrete concentrations of mass that is greater than the average distribution! Currents and eddies in the intergalactic medium?

Ah okay. So while the existence of Black Holes in general is not 100% confirmed there are several candidate one could say are 99%. Given the gravity involved, I don't suppose there is anyway that any sentient being will ever be able to actually directly measure a black hole. Thus, I'm gonna go with: Black Holes are "God."

Oh that is interesting. I had heard the idea of a BH in the center of Milky Way, but didn't exactly pickup that they are hypothesized to be at the heart of _most_ or all galaxies. Interesting! Yes, it does make sense that it would need to be something quite massive to act as the central body for an entire galaxy of several billion stars to revolve around it. Here is my one question though. Assuming it is a black hole at the center or Milky Way, presumably it formed either just before or just after the galaxy began to coalesce. Now I can't remember if they think our galaxy is an first or second generation one, but in any event, 6 to 10 billion years old galaxy I would think (at least)? So why is it that, after that much time for the BH to have cleared the space around it, it hasn't? Instead of a black blank spot with the other side of the galaxy lensing behind it and nothing energetic crashing into it (because it has had plenty of time to clear its surroundings out to extent of its ergosphere I would think?) we got a giant cluster of gass and energetic activity.

You make excellent points Gesch! Wish I had the ability to rebut them. Although I went the social scientist path, I am afraid I have come to largely the same conclusion as you. With one exception: I do retain 'hope'(?) that eventually humans WILL defeat the tyranny of Earth's gravity well (and the myriad other obstacles) and making good use of the solar system will ensue. Even if it is 1000, or 10,000 years from now, that is a lot different than 'never!'