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the asinine cretin

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Posts posted by the asinine cretin

  1. I have no experience with such things, but my guess is that rather than there being a biology programming language, there are libraries for existing languages. For example, a Google search just brought me to some python libraries.

     

    http://biopython.org/wiki/Biopython

     

    This page has a list of relevant python tools under the "Life Science" section. http://wiki.python.org/moin/NumericAndScientific

     

    I'm sure there are similar resources out there for other languages. I just searched for python because I've fiddled with SciPy.

     

     

    Is this helpful at all?

  2. the asinine cretin,

     

    Ok, so I thought I could lurk, but I can't. Too many thoughts half expressed and too many objections unanswered.

     

    I do not know the assumptions and figuring involved in the figure of how many molecules there are in the universe. You know which parts are left out, and which parts are included, and what facts are exptrapolated to arrive at a "plausable" number. And you know it is a guess, and an estimate, that given the starting assumptions the number cannot be greater than so and so, and must be at least so and so, so therefore there must be this many. You know what the definition of "observable" is, which leaves quite a chunk of the universe outside of the figure, and you leave out all the dark matter and energy that is "inside" the observable universe. These omissions that you make, allow you to claim to know something about the universe that I do not know, which you obviously do. But what if I don't know all your assumptions, or what if I don't agree with all your assumptions, or what if I don't know how you treated time in your figuring? Or how exactly you define the border between observable universe material and other than observable material? What if I thought you were talking about ALL the molecules in the UNIVERSE, as if you KNEW. As if you claimed to know something you do not know. Then I might figure you were making it up, and deluding yourself into thinking you had personal knowledge of the universe. That you had an objective certainty about the number of molecules in the universe. That you were making a claim that your model was fact...then my bullshit detector might go off.

     

    Regards, TAR2

    I don't follow. Forgive me, but, is this sincere inquiry, disingenuous obscurantism, or something else?

    Of course I don't "know" how many baryons there are. My understanding is that our best estimate indicates roughly 10^80 baryons in the observable universe. But who cares? What actual point are you trying to make with these rhetorical questions? Are you somehow trying to suggest that empirical estimates of this kind are comparable to belief in religious stories such as Mohammad talking to an angel or flying on the magic donkey? I must be misunderstanding your intent.

     

    Thanks for the reply.

  3. [1.] My personal bullshit detector goes off when Mohammed has a talk with the angel Gabriel.

    [2.] My personal bullshit detector goes off when a scientist/mathematician says they know how many molecules there are in the universe AND that we don't even know anything about what most of the mass and energy in the universe even consists of.

    At least with #2 you can look up the basis of the claim, and it doesn't claim to be anything more than our best estimate given certain assumptions. On the other hand, #1 is something out of the fairy tale genre that asks for your assent, no questions asked. If you're born in the wrong place/time that could be "assent, or else."

     

    P.S. I am aware of plausible estimates of the number of baryons in the observable universe. Such an estimate does not include dark matter or dark energy and I'm not so sure that your objection would be relevant.

     

    As far as the thread topic is concerned, I think some forms of religiosity are "broken" in the sense that they require certitude where there is none. I'm hesitant to say religion must include dogma and confident supernatural beliefs. There are many distinctions that can and should be made. For example, the kind of religious experience described by mystics of various traditions is quite different from the doctrinaire fundamentalism many Americans seem to espouse and promote.

     

    Love everyone, explore the depths of human consciousness, revere and in some sense worship the mystery of being, and so on. As opposed to, "the bible says the earth was created in six days, and by golly, if the king james bible was good enough for jeebus, it's good enough for me." Or the somewhat more sophisticated variant, "complexity, complexity, complexity, mouse traps, bacterial flagella, therefore, Jeebus."

     

    P.P.S. It's very hard to imagine, but I am open to the possibility that some version of one of the traditional religions is true. I haven't ruled out the supernatural a priori, or the idea of an intervening personal God, or of a pantheon of "divine" beings (whatever that even means), or of supreme extraterrestrial beings beyond our comprehension. The issues, at least to me, are epistemological and psychological. I am unaware of a viable religious epistemology/criteria of truth that could sufficiently test and justify religious claims. Second, I think that the psychology of belief and the study of religion as a natural phenomena go a long way toward an adequate explanation of existing religions as purely human constructs.

  4. Interesting. I just googled "Unity Scripting" as mentioned in the video title. How does that work? I have some background with game development so I'm curious. Actually, the last game project I worked on was a space game - but I never finished it (just a hobby).

     

    The games I've done on my spare time (which was years ago when I was a bachelor), involved building out a rendering engine using C++ and a graphics library (last game engine I developed used DirectX 9.0c) as well as writing shaders (HLSL was hot at the time), and then creating, rigging, and to some extent animating meshes in a tool like 3ds Max. I used Photoshop for textures and things. I wrote custom software (rough software that wouldn't win any awards, to say the least) for integrating assets into scenes and "levels." Finally, what might be called scripting in my game was entirely proprietary and bare-bones. The scripting language was syntactically reminiscent of JavaScript but minimal and executed with an interpreter/engine of my own design. Oh, and then the rest of what goes into a game engine, the physics, audio, user input, et cetera. Not the most feasible solo project, especially considering the scale of the games I wanted.

     

    I've only glanced at the site, but Unity seems to be an IDE Of sorts that integrates a full-featured game engine, asset editor, world builder, and "store" for purchasing ready-made assets. If my impression is correct, wow. Maybe the old game development hobby is something I could pick up again. What do you think of Unity? Have you used other game dev technologies/approaches? Does it have good APIs that let you really hack things? Well, rather than bombard you with questions I suppose I could click around their site more and use Google.

     

    Having said all that, what is your game going to be like? Do you have it planned out in detail? Just curious. Peace.

  5. In case anyone is interested.

     

    Electric Propulsion: Which One For My Spacecraft?

     

    Gas Core Nuclear Rocket Engines Promise and Reality

     

     

    Regarding Beamed Power

     

    Photovoltaic Receivers for Laser Beamed Power in Space

     

    Pulsed Laser Illumination of Photovoltaic Cells

     

    Beamed-Energy Propulsion Study (this doc is effin huge, be warned)

     

    NASA Technical Reports Server (search results)

     

     

    VASIMR Related

     

    Ad Astra Publications

     

    Nuclear Electric Rocket

     

    SAFE-400 Fission Engine (400 kW; 1.2x10^3 kg)

     

    Design and analysis of the SAFE-400 space fission reactor

     

    An Ad Astra study (found here) describes a mission using 12 MW VASIMR propulsion for a < 3 month trip to Mars and allocated about 25 mT of mass budget for the reactors (including radiators). It might then take 30 of the SAFE-400 reactors to achieve 12 MW. At 1200 kg each that's about 39 mT; significantly over budget. However, I suppose a megawatt-scale reactor would have a smaller specific mass. I wonder how the SAFE design would scale? What might the mass be for a 1 WM version, or a 6 MW version? (The SAFE-400 is basically the result of some fiddling "on the side" with discretionary money; it's not unreasonable to suppose we could do better with serious funding.) The study also describes an epic 200 MW Mars mission. This very interesting paper was among the references. Multimegawatt NEP with Vapor Core Reactor MHD

  6. In short, they made a metagenome project and among the sequences they found gene homologs that looked very distinct from available sequences. The big question is whether this is due to the fact that these differences are due to low relatedness to known organisms, or whether it just means that we have not explored sufficient genomes yet. The dark matter alludes to the assumption that (if they really are a distinct domain) these organisms are unknown until now. One possible source are giant viruses and they were some studies that alluded that they belong to a very old lineage (which includes the paper mentioned in the OP as well as another from a French group under Raoult late 2010). However, subsequent studies (Williams et al 2011, also in Plos One) using different evolutionary models indicate that there is really little evidence hinting at a fourth domain based on these viruses.

     

    My personal take is also on the conservative side and I do not think that the experimental evidence is currently strong enough.

     

    I hereby applaud and salute you. Thanks for the excellent info.

  7. The main driver behind that push is the fact that domestic production plutonium 238 has been shut down since 1993. Funding to get that domestic production restarted is barely there, and it's only on the NASA side. Producing 238Pu the job of the Department of Energy, and Congress for some reason refuses to fund the DOE side. Logjam.

    I am aware of the current state of Pu-238 and the other things related to that covered in materials that I've posted in this thread. But I'd like to know how you can say that this is the main driver behind the push for ASRGs. I don't dispute that it's a driver, but you make a lot of claims like this that strike me as supposition. If you have sources for these claims please share, if not, please indicate that you're just speculating. Are you personally involved in any of these things? (I actually find it hard to believe that you don't understand the many advantages of ASRGs over RTGs.)

     

    If there was an adequate supply of plutonium 238 NASA would happily continue using RTGs. They are a very simple and very trusted technology. No moving parts. They don't fail. While much more efficient, those Stirling generators are new technology and are significantly more complex than RTGs. Increased complexity means a significantly increased likelihood of failure. That it is new also increases the risk of failure. A lot.

    Again, I'm inclined to dispute this. RTGs have their advantages, but ASRGs are significantly more efficient (even if Pu-238 production were still happening the fuel would be expensive, and radioisotopes are heavy, dangerous, et cetera), and based on what I've read you're wrong that ASRGs add more mass. Some of the sources I've provided state that ASRGs are lighter and that this is a real advantage (I'd actually like to learn more about this as these sources have not gone into detail). Again, if you have sources I'd like to see them. The basis of my impressions can be found in documents linked above.

     

    The ASRGs will be used for low power consumption devices such as sensors and communications. Using them for a high power consumption device such as a VASIMR engine is not going to get a vehicle to Mars. At least not very fast. Do the math. A VX-200 sucks 200 kW of electrical power, or the output of 1400+ ASRGs. At 32 kg per ASRG, the power source needed to supply a VX-200 masses over 45,700 kg. That's just for the power source, not the housing for those 1400+ units or the electrical cable needed to connect them to the engine. All for 5 newtons of thrust.

    Where are you getting your numbers? The 2008 NASA Planetary Science Division Update indicates that the ASRG prototype has a nominal power of 140 W with 0.8 kg of Pu-238 fuel, but gives the mass as 20 kg, not 32 kg. I've also read that the 200 kW VASIMR can serve up 20 Newtons. But you're missing the key thing about my RTG/ASRG speculation, and why I brought it up at all, which was that Po-210 might be used, not Pu-238. This changes everything.

    And I'm interested in the theoretical potential here, not merely existing prototypes. E.g., Entertaining the possibility of fuel other than Pu-238 (the key point being that Po-210 ups things by orders of magnitude). A large ASRG utilizing 10 kg of Po-210 with 30% efficiency would obviously have very different specs than a 0.8 kg Pu-238 device, or multiple 140 W Pu devices that add up to similar power output. It's a fun theoretical exercise and not something I'm interesting in bickering with you about. Your condescension and habitual naysaying anger me.

     

    I think that for realistic power in space you will need a nuclear reactor of some type, gaseous fission would be tricky and difficult. Magnetic confinement of the reacting plasma would seem to be the answer but as far as I can see there is no hope of creating magnetic fields strong enough to confine such a heavy ion plasma.

     

    http://www.spacedail..._Space_999.html

     

    http://en.wikipedia....fission_reactor

     

     

     

    http://en.wikipedia...._reactor_rocket

     

     

    Thanks. That is interesting. Reading those links now. What I'm curious to know is to what extent such things are being actively developed right now. I mean, is this a possible solution for 100 years from now, 50 years from now, etc? It's encouraging to see ASRGs in the agenda-setting NASA docs, for example.

     

    (Disclaimer: What follows is purely "what if" speculation for its own sake and there is no need to take a shit on it. Assume I know the obvious. If you're offended by this, just consider it sci-fi or something. Thanks.)

    Clearly the killer problem with this Martian refill idea is that it assumes some serious infrastructure on Mars (for example, the neutrons required by the production process would probably require building and maintaining a large nuclear facility, as well as mining operations, refineries, and so on) . . .

    Bismuth might be obtained as a byproduct of mining and refining metals such as gold, silver, copper, cobalt, nickel, tin, etc. from asteroids. Such operations would presumably be established independent of the Polonium-210 fuel idea. Rather than having facilities on Mars it would probably make more sense to have the production capabilities on Phobos or Deimos. Perhaps one of these bodies is itself rich in relevant materials. A significant mining-refining operation on such a body would likely include a substantial nuclear reactor which could supply the neutrons. The production of short-lived but super high output Po-210 power source "refills" might then be a relatively painless byproduct of profit-driven infrastructure development. Basically, operations on Phobos receiving and processing materials from NMOs and asteroid belt objects; operations on Luna receiving and processing NEO materials; and a two-way express route powered by the Po byproducts.

     

    Of course if space operations were already that advanced the current topic of powering VASIMR and the like would be obsolete. Again, this is just a fun imaginary thing. But I do suspect that Po-210 will prove to be a useful fuel with a variety of applications in the future. The theoretical potential is interesting anyway.

     

    As far as the real topic of getting the VASIMR in operation in the near future, based on what I've read, the direction they seem to be going is solar power. Of course this limits the applications considerably. But I recall something about a 2 MW solar array with multijunction photovoltaics with greater than 30% efficiency. I don't know how accurate or current this information might be. And I'd be curious to know what kg per kW ratio they can achieve. Must continue Googling...

     

    Although, for the lunar cargo spacecraft, perhaps solar arrays in cis-lunar space could beam power to the craft via microwave, thus radically reducing the mass required by power systems. I've researched space-based solar power and the possible efficiency is actually very good, but the receivers tend to be huge and the distances involved are of course far less than would be required for a lunar-bound spacecraft. Maybe laser power beaming from cis-lunar arrays and/or a lunar surface array.It would be interesting to explore such concepts anyway.

     

    P.S. This site is fun. http://www.asterank.com/

  8. The underlying findings are interesting but the NS covering is too sensationalist for me

     

    Thank you. As a non-biologist that's kind of what I was wondering. Where does the hype meter register on this? I have to confess that at first hearing the use of "dark matter" made me cringe a bit. And I agree, the facts are extremely interesting. When I get some time I'd like to find resources that are more technical.

     

    P.S. Why did someone give juanrga's post a -1? Please explain.

     

    I like the name but at the same time it is inciting youtube viewers to some odd speculations with respect to mythical creatures such as midi-chlorians. As much as I want to be a Jedi I don't believe that by increasing my biological dark matter count that I will suddenly be able to pick up airplanes with my mind, or affect the colour of a plasma/laser saber.

     

    They leave much to the imagination with these information pieces. Genetic assemblies are nothing new and I'm sure there is plenty of research into passive processes whereby genetic material self assembles due to predisposition. CharonY has mentioned a few things about early forms of genetic matter that are similar in concept to what I just described, in however limited detail.

     

    The fact that they may have found something structured that is not anything that we commonly observe today, that they may have overlooked is exciting. Calling it a new domain is hardly exciting because they keep changing the taxonomic descriptions of life every few years. But again, not cell life, not virus, it is something interesting if in fact it is organized life. Especially if it is concluded to be a form of life, as mentioned it would not be cellular and this is quite in contrast to present theory which places the cell as the smallest unit of life.

     

    The presumed benefits of this investigation seem to be the discovery of organisms that might be involved in manipulating both cellular organisms and viral matter such that we see rise to various illness'. Obviously if we can find and control the activities of anything that makes us sick, we are better for it, and this is a major plus to this investigation.

     

    Thank you for the interesting remarks.

  9. Zubrin's The Case for Mars talks about how Mars might be terraformed. It's a good read all around. There is also a Springer book that comes to mind called Terraforming. There are a lot of interesting ideas out there. Sad to say that while Venus is one of my favorite worlds, I've been forced to give up on the dream of terraforming it. There are some problems that I think are insurmountable. I still like the idea of aerostatic Venusian outposts and colonies though. biggrin.gif

  10. D H,

    Okay, well, your post is about 5% relevant to me. Mostly stating the painfully obvious and repeating things I've said or alluded to, which is obnoxious. Not an interesting convo.

     

     

     

    With so much machinery required to produce electricity from an RTG why not just just go for a real nuclear reactor? Something like a gaseous fission reactor should have a pretty good watts per kilogram ratio, use it to produce electrical power, it would radiate in the deep UV, possibly this could be turned directly into electricity? (I know I've got gaseous fission in my brain)

     

     

    Moontanman,

     

    The more I look into them the more intrigued I am by stirling radioisotope generators. The tech exists and has demonstrated to be both significantly more efficient and lighter than RTGs; at least according to the stuff I've been reading. There is a big push to finish its development.

     

    Fission power back on NASA's agenda

    Using Nuclear Fuel for Future NASA Missions...

     

    Advanced Stirling Radioisotope Generator Flight Development

     

    The TiME mission is completely awesome and will likely use the tech.

     

    The NASA Space Technology Roadmaps and Priorities document, as of May 4th of this year, mentioned Advanced Stirling Radioisotope Generators 35 times.

     

    "NASA and DOE have been developing advanced RPSs that would use Stirling engines to replace thermoelectric converters. Because the energy conversion efficiency of the Stirling engine under development is about 5 times that of thermoelectric converters, Stirling engines require significantly smaller quantities of Pu-238 to achieve similar power levels."

     

    "The planetary science decadal survey committee cited its highest priority for near-term multimission technology investment was the completion and validation of the Advanced Stirling Radioisotope Generator. (NRC, 2011, p. 11-5)"

     

     

    "There were two technologies, Advanced Stirling Radioisotope Generators and On-Orbit Cryogenic Storage and Transfer, that the committee considered to be at a "tipping point," meaning a relatively small increase in the research effort could produce a large advance in its technology readiness."

     

     

    In other words, don't be surprised when we start seeing these on outer solar system spacecraft. Very cool.

  11. No news is no news. Or in some cases, it's bad news. Lots and lots of proposed technologies start with a flourish but then just fade away.

    In other words you don't know?

     

    What you are doing here is accounting for the mass of the fuel but failing to account for the mass of all of the infrastructure needed to make that fuel useful. The decay of polonium 210 generates heat. VASMIR runs on electricity. You are ignoring the fairly massive infrastructure needed to convert that heat into electricity plus the extremely massive infrastructure needed to ensure that the PO-210 remains safely encapsulated even in the case of an explosion. That alone changes your many kilowatts per kilogram into many kilograms per kilowatt. Then there's the problem of the efficiency of that conversion of heat into electricity. RTGs are simple devices with no moving parts. The downside: They are extremely inefficient. Typically efficiency is about 5%. Your two inch cube of polonium-210 would generate about 7 kW of electricity.

    Right. I was only talking about the fuel and not infrastructure. But I wouldn't call thermocouples "extremely massive infrastructure." There are things to consider beyond just the fuel? No kidding, everyone knows that. Perhaps you mistook this for a formal proposal. lol. Condescension isn't the reply I was hoping for.

     

    You evidently missed my comments about efficiency. Based on modern RTGs I suggested 7% as a reasonable efficiency but later mentioned a contemporary prototype device that is said to attain 30% efficiency. Since I'm freely speculating about what's possible, and not trying to be cynical, I think it's okay to imagine what could be done with a 7-30% efficient system.

     

     

    Swap it out? With what? Another PO-210 based RTG? Won't work. Polonium 210 is highly radioactive. The polonium doesn't care if the generated heat is put to productive use or is just radiated out into space.

    Moontanman's interpretation is correct. Obviously the radioisotope would be manufactured in situ on Mars. Clearly the killer problem with this Martian refill idea is that it assumes some serious infrastructure on Mars (for example, the neutrons required by the production process would probably require building and maintaining a large nuclear facility, as well as mining operations, refineries, and so on), but if we could already develop Mars on that scale it's hard to see why the VASIMR discussion would be relevant. In other words, it's a circular idea. There are ways to make it more worthwhile but I wouldn't actually say that I think it is workable. Just indulging in some stream of consciousness.

  12. "A two inch cube of polonium-210 would emit 140kW"

    That's about 600 ml of volume. The density is about 9 so

    It would weigh about 6. Kg

    1 mg is about 4 curies

    So you have 24 MCi of radioactive material

    About 50mCi killed someone and that dose is estimated as about 200 times the lethal dose.

    So the lethal dose is about 250µCi

    So 24,000,000 Ci is about 100,000,000,000 times the lethal dose for a human.

     

    And, in the event of the spacecraft exploding...

    And don't forget that with 210 Po the generator has a half life of about 6 months

    (data from wiki, but any errors in maths are my own responsibility.

     

    It's definitely super lethal stuff. However, so is Pu-238 and we're still launching kilos of the stuff into space. The RTGs are pretty solid. An RTG from the aborted Apollo 13 mission is at the bottom of the sea some place. Actually dispersing the material in the atmosphere like you suggest isn't really going to happen even in the worst catastrophic failure. We've put Po-210 in orbit, and the Soviets certainly launched some good chunks of the stuff with their funny looking moon carts. But anyway, if your point is that it's dangerous stuff, I wholeheartedly agree.

     

    At least the majority of the Po-210 will decay into Pb-206 quite quickly. If Apollo 13 had used Po-210, a much smaller amount of dangerous material would have been needed and it would probably have been basically gone before I was born.

     

     

    "To minimize the risk of the radioactive material being released, the fuel is stored in individual modular units with their own heat shielding. They are surrounded by a layer of iridium metal and encased in high-strength graphite blocks. These two materials are corrosion- and heat-resistant. Surrounding the graphite blocks is an aeroshell, designed to protect the entire assembly against the heat of reentering the Earth's atmosphere. The plutonium fuel is also stored in a ceramic form that is heat-resistant, minimising the risk of vaporization and aerosolization. The ceramic is also highly insoluble." - Wikipedia: RTG

     

    Here's a bit of NASA's safety analysis for the Cassini-Huygens mission, which launched 3 RTGs and 129 radioisotope heaters. http://saturn.jpl.nasa.gov/spacecraft/safety/fseisd.pdf

  13. There you go. Problems everywhere you look. Incredibly low thrust, incredibly high power consumption. Non-existant generators, at least to the extent needed to generate meaningful thrust. Plans to use VASIMR to get people to Mars predicate one kilogram per kilowatt generators. The Soviet Union's TOPAZ generator: 100 kilograms per kilowatt. The United State's NERVA generator: 65 kilograms per kilowatt. Predicating nearly two orders of magnitude in improvement is in general a no-go. About the only place that works is in the world of computing, Moore's law. There is no equivalent to Moore's law in space technology.

     

    Interesting. Has anything changed since 2010? As I mentioned in another thread, Ad Astra says that the VASIMR is to be tested on the ISS in the near future. I've not seen any substantial details.

     

    Non-existant generators, at least to the extent needed to generate meaningful thrust. Plans to use VASIMR to get people to Mars predicate one kilogram per kilowatt generators. The Soviet Union's TOPAZ generator: 100 kilograms per kilowatt. The United State's NERVA generator: 65 kilograms per kilowatt.

     

    A two inch cube of polonium-210 would emit 140kW. That could definitively get you many kilowatts per kilogram; perhaps the two orders of magnitude you desire when compared with your numbers. The half-life is less than five months but I imagine a very compact and light weight RTG could power a VASIMR on a robotic spacecraft and ramp it up to extreme speeds for outer solar system recon and the like.

     

    (I haven't researched this or anything, just looked up some numbers of radioisotopes and talking out of my ass.)

     

    Just speculating here, but if polonium-210 production could be carried out on Mars you could make the trip to Mars in a few months or less and then obviously swap out the little power source for the return trip. Apparently it's been used in RTGs already so it's not that far-fetched.

     

    According to the VASIMR wikipedia page the 200kW engine is serious business.

     

    "Results presented to NASA and academia in January 2011 have confirmed that the design point for optimal efficiency on the VX-200 is 50 km/s exhaust velocity, or an Isp of 5000 s. Based on these data, thruster efficiency of 72 % has been achieved by Ad Astra, yielding an overall system efficiency (DC electricity to thruster power) of 60% (since the DC to RF power conversion efficiency exceeds 95%)."

     

    1 kg of polonium-210 emits 140kW, and good RTG efficiency by today's standards is something like 7%. Therefore, 20 kg of radioisotope could create a worthy generator. No? Also, I tend to suppose that the 7% RTG efficiency could be improved upon in this day and age.

     

     

    The wiki article mentions something about a craft with a MW solar array and five of the 200 kW thrusters. Hmm.. It might look goofy, but if it works... And maybe with the expected innovations in photovoltaic tech that I often hear about such an array wouldn't be as ridiculous as I'm imagining. I'm thinking that the ISS arrays total to something like 150-200kW (I could be wrong); extrapolating from that to 1 MW results in a rather goofy spacecraft.

     

    It looks like there really isn't a Po-210 supply. Russia has one facility that produces less than 100 grams per year. That's really about it. It must have been produced in notable quantities in the past given its use for Russian lunar rovers and some U.S. experiments and things. Plutonium-238 seems to be tending toward the same fate at the moment. I wonder if Po-208 is viable for use in an RTG? The half-life of nearly 3 years seems more useful than the 5 months of Po-210. I wonder what the heat energy would be for a kg of the stuff. Oh well...

     

    P.S. The prototype ASRG power system attains 30% efficiency and a fourfold reduction in fuel. With plutonium-238 as the energy source it could power a spacecraft for >14 years. If the design could be effectively scaled up for the 200 kW demands of VASIMR... The prototype seems to get 175 watts per kilogram of Pu-238, or about 6 kg per kW. It's a good step I suppose. Or maybe the uber efficient design of the ASRG with a more concentrated fuel such as Po-210 or whatever. Yeah, no doubt 30 or 40 kW per kg could be worth something. A radioisotope in between Pu-238 and Po-210 would be ideal. Oh well.

  14. Anyone know if the VASIMR is really legit? I hear they are supposed to put VASIMR thrusters on the ISS in the near future. On the other hand, I can remember Robert Zubrin vehemently trashing the VASIMR and basically saying it's a scam. I can recall a PBS show that spent ten minutes talking about the VASIMR and thought it was a load of crap. As if the only options are the VASIMR or a ridiculously long chemical rocket journey. If my impressions are correct it was very skewed pro-VASIMR propaganda with Neil deGrasse Tyson as the host.

     

    P.S. Here is the Zubrin screed I was thinking of. The VASIMR Hoax

  15. Ring species are an example of speciation that results from accumulated microevolution, otherwise called adaptation or mutation driven by natural selection. The resultant speciation could be categorized as macroevolution, particularly at the end populations where the ability to interbreed has been interrupted by the accumulated change.

     

    Again, I'm familiar with what ring species are. I was hoping for a summary description of macroevolution and an elucidation of why ring species are a particularly good example of this. The problem I have with ring species as an example of macroevolution is the possibility of gene flow and ambiguity. I do think that ring species are good for illustrating why categorical thinking about species is wrong. Where I'm coming from here is trying to communicate with a creationist. My concern is that the ring species example might complicate things.

  16. I'm hoping a biologist will happen upon this and be kind enough to reply. I've been trying to come up with a short summary of what I understand the distinction to be between micro and macro evolution. Is the following correct? If not, what would be correct? Thanks.

     

    Microevolution refers to evolution at the species level. Evolution as it occurs above the species level involves microevolution and speciation, which is sometimes referred to as macroevolution.

     

     

    Basically, the distinction comes down to evolution (so-called "microevolution") within populations that are exchanging genetic information vs. microevolution between gene pools that are separate and necessarily diverging. Thus, microevolution will not produce new species on its own (e.g., a dog will never bring forth a non-dog), but if speciation occurs microevolution may produce distinct lines of descent that can become highly divergent over time (e.g., the split at the common ancestor between hippos and cetaceans has lead to very distinct species).

     

    I would also welcome and appreciate book recommendations.

     

    Regards.

     

    P.S. If any creationists happen upon this I would be curious to hear what you understand "macroevolution" to mean. I encounter these terms in the context of creationist argumentation almost exclusively anyway.

  17. ok so this is for asinine cretin, i will state how i interpret that (very very simplified down to the basics) if you concurr and would like to continue i will, if you disagree please say so, so-my interpretation- we dont observe it today because it both started and stopped happening in the past. i will add myself although he didnt say this but it needs to be pointed out -that both the start and stops of his story were both unobserved. (again i have left out the time he mentioned and the process etc etc.) if you find fault anywhere please say so... thank you. shall i continue lol?

     

     

    What started and stopped happening in the past? Evolution? If so, what is the basis of this claim? If you invoke the shape of evolution, stasis, punctuated equilibrium, or any other such thing I will be forced to ironically remind you of your radical epistemology. But I should let you clarify and finish.

     

    So, the start and stop of evolution were both unobserved? Who didn't say it? Dawkins? I'm a bit confused. Thanks.

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