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Moontanman

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Posts posted by Moontanman


  1. 4 hours ago, swansont said:

    You made no modifiers to your claim.  Only after-the-fact, once the claim was rebutted.

    It's moot, anyway, since the claim I was responding to was "size is not a valid argument, technology could eventually conquer the entire local cluster of galaxies given a few hundred million years." followed by the claim that the only missing piece was fusion. "The only current flaw I am aware of is our lack of controlled fusion."

    The side-track into radio signals was just that — a side track, based on an unsupported implication that the interstellar medium is responsible for the decrease in signal strength. I brought that up because it ignored the (IMO) more obvious 1/r^2 decrease, and also fit in with a previous misconception that the interstellar medium is something other than a near-perfect physical vacuum, exceedingly sparsely populated with matter.

    Other arguments have morphed along the way, too. Every time a shortcoming is pointed out. No agreement that the claim is flawed. Just a rewording of the claim.

     

     

     

    I was trying to clarify the assertions I had made. 

    Ok, lets see how your assertion that we are sending out signals with the intention of notifying aliens we are here VIA the message sent by Arecibo.

     https://www.iop.org/resources/topic/archive/seti/index.html

    Quote

    This has been attempted several times, the best known of which was transmitted by the Arecibo radio observatory in 1974. The message was a sequence of binary digits, which, when decoded shows pictorial and mathematical representations of a human being, our solar system and DNA.

    It was aimed at the M13 globular cluster of around 30 000 stars 21 000 light years away, which will no longer be there by the time the message arrives – it was intended more as a demonstration of technology and to be thought-provoking.

    Although the power of deliberately transmitted beams doesn’t drop as rapidly as with accidental broadcasts, they are still only likely to be strong enough to be detected within perhaps a few hundred to a few thousand lightyears. The effective range of a transmission depends on several factors, including the frequency, bandwidth and transmission power, as this range-calculator shows.

    Even for messages at high power, any extraterrestrials waiting to hear from us could need a radio dish several kilometres across. They may not have the budget for it.

    It is quite possible that I am confused about the interstellar medium interfering with radio signal leakage detection. I concede that point. 


  2. 3 hours ago, swansont said:

    I am not prepared to make a specific pronouncement. I know that atoms didn't even exist until about 380,000 years after the BB, and then you'd need for stars to form (that took another few hundred million years) and then go supernova, because at that point you only have H, He and Li in the universe. So you have to add in that life cycle of stars just so you have some Carbon. You probably need a second round of star formation/supernova, too, in order to form the heavier elements that one would need as an advanced civilization — probably not going to do anything advanced without metals. I don't know how many billions of years each stage would take. 1? 2? 3?

    Nonetheless, time could very well separate civilizations as well as distance.  If civilizations are rare this has to be a factor in the Fermi paradox. IMHO there is no Fermi paradox, the paradox is an illusion I would assert we see what should expect to see...

    https://www.forbes.com/sites/quora/2017/01/27/how-far-into-space-can-radio-telescopes-hear/#57df9f2f5de7

    https://en.wikipedia.org/wiki/Fermi_paradox

    Quote

    Radio technology and the ability to construct a radio telescope are presumed to be a natural advance for technological species,[52] theoretically creating effects that might be detected over interstellar distances. The careful searching for non-natural radio emissions from space may lead to the detection of alien civilizations. Sensitive alien observers of the Solar System, for example, would note unusually intense radio waves for a G2 star due to Earth's television and telecommunication broadcasts. In the absence of an apparent natural cause, alien observers might infer the existence of a terrestrial civilization. It should be noted however that the most sensitive radio telescopes currently available on Earth would not be able to detect non-directional radio signals even at a fraction of a light-year, so it is questionable whether any such signals could be detected by an extraterrestrial civilization. Such signals could be either "accidental" by-products of a civilization, or deliberate attempts to communicate, such as the Arecibo message. A number of astronomers and observatories have attempted and are attempting to detect such evidence, mostly through the SETI organization. Several decades of SETI analysis have not revealed any unusually bright or meaningfully repetitive radio emissions.

     

     

    3 hours ago, swansont said:

    Even after that, you need a solar system around the star that ignites. Planets have to form and cool, and any early-formed life would have to survive bombardment/collision from anything left over from planet formation, which is more frequent for a young planet. So you likely have a delay before life takes hold on the new planet

    Recent research has pushed the possible existence of life on Earth back to more than 4 billion years, this would appear to indicate that life starts as soon as it's possible. 

    3 hours ago, swansont said:

    We know life on earth is billions of years old, so I can't make sense of this.

     

    I was referring to life in the galaxy, there are so many ifs involved that this is nothing but speculation but even if life in not rare civilizations could still be separated in in not only space but in time as well. A million civilizations could be separated by thousands of light years but also hundreds of thousand years in time. At any one time there could only be a handful of civilizations active and those would likely be separated by tens of thousands of light years in space. A civilization that far away would not be aware of us and unless they were intentionally sending out a high powered omnidirectional signal for tens of thousands of years we would be unaware of them. And due to the speed of light limitations they could not be aware of us...

    There is no Fermi Paradox, we see what we should expect to see when passively looking for signals of ET... 

     

    3 hours ago, swansont said:

    Where? It wasn't in the section on radio.

    Nothing about interstellar attenuation being the stumbling block, though, which was the claim I objected to.

    Ok, I'll concede that but the fact does remain that we could not detect a civilization equal to ours in the Alpha Centauri system unless they were intentionally trying to be recognised. 

    3 hours ago, swansont said:

     

    Pretty weak defense for moving the goalposts, IMO.

     

    No, not at all, the signal you are referring to was not omni directional, it was directed at the Magellanic clouds 16,000 light years away, it wasn't repeating over time and if we received such a signal it would be discounted. To have a real attempt at letting aliens know we are here would take a very powerful omnidirectional signal that we are currently incapable of generating due to both the power requirements and lack of infrastructure. 


  3. 1 hour ago, Prometheus said:

    Just found this channel and had to share:

     

    I love it, the micro cosmos is, IMHO, a source of information of how complex life advanced to us. Protests were the first step towards us!  


  4. 4 hours ago, swansont said:

    There's no way that advanced life could have existed for the first several billion years of the universe, and arguably could not have happened for a few billion beyond that.

    Please be specific, how far back could life have existed? If it's just a few thousand years then you have a point if life could have existed several billion years ago I don't think you have a leg to stand on. 

    4 hours ago, swansont said:

    That says nothing about the attenuation by the interstellar medium.

    Ok, even though it does state .3 light years as the limit. 

    This one says 16 light years for certain signals and explains why military radar is different. 
    https://www.forbes.com/sites/quora/2017/01/27/how-far-into-space-can-radio-telescopes-hear/#77c621915de7

    Quote

    The radar beams are potentially detectable by current radio facilities such as the Arecibo Observatory and FAST and the planned future Square Kilometer Array at distances of tens to hundreds of thousands of lightyears. However, they are transient and only very rarely aimed at any star because they’re tracking objects moving across the sky in the foreground. So unless an astronomer on an Earth duplicate at Tau Ceti were aiming their equivalent of the Deep Space Network directly at the solar system, we would be very unlikely to pick up those radar beams.

    http://curious.astro.cornell.edu/about-us/131-observational-astronomy/seti-and-extraterrestrial-life/seti/795-wouldn-t-the-vast-distances-of-space-distort-seti-signals-into-unintelligeble-forms-intermediate

    Ok, I can't find a direct reference to the interstellar medium problem, I know I've seen it, in fact i have posted a link to it in other threads in the past but for some reason I am google blind at the moment. I can't seem to find the right search criteria 

    4 hours ago, swansont said:

    Again, this would only mean that the signal carries a little further, and if a weak signal is essentially gone after a LY (your contention) then a stronger one is gone after 2 or 3. Which makes zero difference.

    https://www.forbes.com/sites/quora/2017/01/27/how-far-into-space-can-radio-telescopes-hear/#77c621915de7

    Quote

    The radar beams are potentially detectable by current radio facilities such as the Arecibo Observatory and FAST and the planned future Square Kilometer Array at distances of tens to hundreds of thousands of lightyears. However, they are transient and only very rarely aimed at any star because they’re tracking objects moving across the sky in the foreground. So unless an astronomer on an Earth duplicate at Tau Ceti were aiming their equivalent of the Deep Space Network directly at the solar system, we would be very unlikely to pick up those radar beams.

     

    4 hours ago, swansont said:

    You didn't say concentrated effort. You said we don't do it.

    Now you are just being pedantic... 

    4 hours ago, swansont said:

    Drones are not cars, and don't operate in the same complex environment. Are any vehicles which drive in traffic doing so in anything other than a test program (typically with a driver on hand for when it fails)? I keep reading about them hitting pedestrians. Also how you can trap them

    The tech is advancing do rapidly I am not willing to use current problem to condemn the inevitability of autonomous cars... or airplanes... 


  5. 8 hours ago, swansont said:

    I don’t believe the math work out for that. 50k LY in radius and 1000 LY thick is a volume of less than 10^13 cubic LY. A million civilizations means they require a volume of less than 10^7 cLY, or a radius of ~200 LY (assuming equal spacing for max separation)

     

    Not if they were a million years apart in time, there are, estimate, 500 billion stars in the milky way, if one in a million have an advanced civilization then 500,000 of them exist but divide that by the age of the galaxy, I'm not sure what that is but let's just say a ballpark figure of 10 billion years. If an advanced technological civilization lasts 10,000 years then they could be a million years apart from each other in time. 

     

    8 hours ago, swansont said:

    So a million civilizations could not all be thousands of LY apart. For any one that is that isolated, many others have to be much closer.

    They don’t have to come here, we just need to be able to detect them.

    So these are impediments for them colonizing but somehow not for us?

    And now world building is in the inevitable march of technology?

    Citation needed.

    We seem to be able to do radio astronomy. The interstellar medium doesn’t filter those signal, often over much, much greater distances (and attenuation is an exponential)

    https://en.wikipedia.org/wiki/Fermi_paradox

    Quote

    Regarding the first point, in a 2006 Sky & Telescope article, Seth Shostak wrote, "Moreover, radio leakage from a planet is only likely to get weaker as a civilization advances and its communications technology gets better. Earth itself is increasingly switching from broadcasts to leakage-free cables and fiber optics, and from primitive but obvious carrier-wave broadcasts to subtler, hard-to-recognize spread-spectrum transmissions."[111]

    Quote

    Radio technology and the ability to construct a radio telescope are presumed to be a natural advance for technological species,[52] theoretically creating effects that might be detected over interstellar distances. The careful searching for non-natural radio emissions from space may lead to the detection of alien civilizations. Sensitive alien observers of the Solar System, for example, would note unusually intense radio waves for a G2 star due to Earth's television and telecommunication broadcasts. In the absence of an apparent natural cause, alien observers might infer the existence of a terrestrial civilization. It should be noted however that the most sensitive radio telescopes currently available on Earth would not be able to detect non-directional radio signals even at a fraction of a light-year, so it is questionable whether any such signals could be detected by an extraterrestrial civilization. Such signals could be either "accidental" by-products of a civilization, or deliberate attempts to communicate, such as the Arecibo message. A number of astronomers and observatories have attempted and are attempting to detect such evidence, mostly through the SETI organization. Several decades of SETI analysis have not revealed any unusually bright or meaningfully repetitive radio emissions.

    8 hours ago, swansont said:

    What makes military radar immune to “fizzling out”?

    Military radar is both high powered and directional, radio leakage is not. 

     

    8 hours ago, swansont said:

    One short message directed at the magellanic clouds is hardly a concentrated effort to draw attention to ourselves... 

    8 hours ago, swansont said:

    Not really. They are not reliably autonomous.

    There are Military drones that can take off and land autonomously and autonomous cars already exist as well as tractor trailers.   


  6. 15 minutes ago, swansont said:

    I guess you must be in the "there are no aliens" camp, too, seeing as there are no actual barriers to interstellar space travel, and your answer to the OP sounds like it's "no, space is not too big".

    If not, where are they?

    They avoid gravity wells... Actually you have to assert that aliens want to come here before you can say anything. Time is also a factor, do alien civilizations last forever? Ours has lasted a few thousand years so far, time is as big a factor if not larger than space. There could have been a million civilizations in the Milky Way so far and they could be separated by not just thousands of light years but thousands of years as well. I am of the "opinion" that planets would be avoided due to the fact that life has adapted to the earth, finding an earth like planet is no guarantee that we could live there. In fact slight variations in chemicals could make a planet uninhabitable to us even though the life that has adapted to it is prolific. It makes much more sense to build your own worlds than to try and find a world that happens to be perfect for you. 

    Some alien specialist might be interested in us for various reasons but landing on the white house lawn would destroy the study. There is no reason to think that aliens would want to contact us and the idea that we could simply see them through their radio "leakage" is false. It's doubtful that we could detect a civilization identical to us at Alpha Centauri unless they were specifically pointing a high powered transmitter directly at us. Our radio leakage fizzles out within a light year or so due to the interstellar medium. 

    Military type radar would be an exception but it would unlikely be a repeating signal and we have detected such signals from various places in our galaxy but they are not given weight because they do not repeat. 

    I think we don't see aliens because that is exactly what we would expect to see unless they are intentionally signaling us and we do not do that, why should they? 


  7. 8 minutes ago, Phi for All said:

    Do you really think most drivers could learn 3D? I don't, and I can't even imagine what it would cost to insure a flying car, much less all the things it might collide with. Right now I'm probably not covered if I plow into the 35th floor of a high-rise building. Also, we're going to need a few orders of magnitude more air-traffic controllers. I'm skeptical that energy is the only thing flying cars suffer from.

    Self driving cars are already a thing, why not self flying cars? 


  8. 1 minute ago, swansont said:

    On the contrary. Technology marches on and I'm in that parade. I've been doing R&D for >25 years. Not requiring new physics is an insufficient answer. I've witnessed firsthand that every time you try to get an incremental improvement that some new problem crops up, usually something unanticipated, that needs to be solved. There are theoretical limits to everything, even if you aren't aware of them.  

    "technology marches on" is a slogan, not science. It's not even a guarantee. We've been "50 years away" from fusion for ... 50 years. Flying cars are not ubiquitous  — and for good reasons, that people didn't seem to discuss back in the day, and reminiscent of the arc of this thread. There's no new physics required for them (either of them), after all.

    Fusion is the only technology required for star travel via McKendrick type artificial worlds that don't already possess. Developing the technology to build such worlds may not be easy but the engineering has been worked out. Distance is not a limiting factor given fusion, when you can build worlds supporting many thousands of people miles long and wide encased in the debris left over from their making from asteroids the idea of a destination becomes close to meaningless. Yes i am speculating but I am not speculating about things that are in violation of what we know to be possible. No FTL, no force fields, no Clark Tech, just fusion. If we can't control fusion then we might be limited to building a Dyson swarm around our current fusion power source but even that means many thousands of times the surface area of the Earth and there are other possibilities for star travel like probes humans are stored electronically and reproduction occurs after the space craft gets there. Maybe hundreds of thousands of years after launch. 

    12 minutes ago, swansont said:

    On the contrary. Technology marches on and I'm in that parade. I've been doing R&D for >25 years. Not requiring new physics is an insufficient answer. I've witnessed firsthand that every time you try to get an incremental improvement that some new problem crops up, usually something unanticipated, that needs to be solved. There are theoretical limits to everything, even if you aren't aware of them.  

    "technology marches on" is a slogan, not science. It's not even a guarantee. We've been "50 years away" from fusion for ... 50 years. Flying cars are not ubiquitous  — and for good reasons, that people didn't seem to discuss back in the day, and reminiscent of the arc of this thread. There's no new physics required for them (either of them), after all.

    Flying cars suffer from a lack of an energy source, nothing more. 


  9. 3 hours ago, swansont said:

    You should win some kind of award for missing the point.

    I think I am making a point you refuse to consider, technology marches on, I have suggested nothing that requires new physics yet you continue to dismiss the possibilities based on what we can currently do much like the quote I gave. 


  10. People who think Mars is a great place to colonise should spend a year in Antarctica, Mars is far less hospitable, much harder to get to, and out of range of any possible timely help... Antarctica is a paradise compared to Mars but you don't see lines forming to homestead Antarctica... 

    13 minutes ago, Moreno said:

    What would be temperatures on Venus if it would be completely Earth-like?

    Earth at the orbit of Venus would be somewhat warmer, probably too warm to maintain Earth like conditions. Venus receives twice as much energy from the sun as the earth does and it is thought that oceans would begin to evaporate and a runaway greenhouse would ensue. As recently, according to some sources, as 2 billion years ago Venus might have had earth like conditions even with oceans and life but the sun is steadily getting warmer and will eventually do to the Earth what it did to Venus. 
     

    8 minutes ago, John Cuthber said:

    If it was completely Earth like, it would have completely Earth like temperatures.

    For a while... 


  11. 19 hours ago, swansont said:

    So you've moved the starting line of the marathon a few meters down the road. And the Kuiper belt is about a factor of 10 further out. 

    Highlighting these steps as significant means you're completely ignoring the scale of the trip. You're getting on your log raft to go across the ocean and saying "Don't worry. We won't jump on until the water is neck deep, and besides, I've packed a lunch." 

    Or Sundance complaining he can't swim when it's the fall that will kill you. You are, quite literally, missing the big picture.

    Ok you win, man will never reach the moon because we can't jump high enough... 

    Quote

    The demonstration that no possible combination of known substances, known forms of machinery and known forms of force, can be united in a practical machine by which men shall fly along distances through the air, seems to the writer as complete as it is possible for the demonstration to be. 
    — Simon Newcomb, 1900

     


  12. 7 hours ago, swansont said:

    But I think that's exactly what you are doing. Moving about the solar system is closer to log rafts, while interstellar travel is the 747.

    That's what you are proposing. Jupiter, one of the stopovers you mentioned, is less than a light-hour away from earth, so it's about 0.01% of a light-year. IOW the scale of this problem is 3 or 4 orders of magnitude larger than whatever we have to overcome for moving about the solar system.

    Jupiter is not a stop over for interstellar travel, Jupiter is in fact a site for manufacturing habitats. The moons and Lagrange points of Jupiter contain all the materials necessary to build habitats. This would be the starting point for colonization of the solar system which would eventually lead to things like a Dyson swarm, and colonization of the Kuiper belt and the Oort cloud. A these habitats would be the next step for moving on out, it might take centuries to develop the technology to build habitats and set up laser highways and or stations to accelerate volatiles and other supplies to traveling habitats but the possibilities are not limited to stopping for gas...    


  13. 14 hours ago, swansont said:

    I don't see the relevance of it. Stopping for gas after ~0.01% of your trip is over doesn't seem like it's in the critical path of success.

     

    The relevance is that no one is saying we will build a star ship in earth orbit and take off for the nearest earth like planet. It's like expecting European humans who were building log rafts to suddenly build 747's and fly to north america. We will build movable habitats for centuries all over the solar system before we even think of the oort cloud. The idea of a generational ship is not impossible and if you are taking your home with you stopping at some point to build more habitats is hardly stopping for gas in fact gas and dust could be harvested with out stopping and going from our Oort cloud to the next is not unreasonable. Why would you stop for gas at 0.01% of your trip? I don't get that.  


  14. On 7/13/2019 at 3:46 PM, swansont said:

    No. Why would you think it would?

    Because you seem to be dismissing my assertions of the beginning taking place in the solar system... 

    On 7/13/2019 at 4:05 PM, MigL said:

    Intelligent machines depend on the 'bags of protoplasm' having achieved an intelligence level facilitating their construction.
    As such, they would be even more scarce ( being equivalent to a subset ).

    Not all intelligent life will develop intelligent machines.
    Not all will develop space travel.
    Not all will be able to communicate with EMR.

    Imagine if we had evolved underwater like dolphins/whales.
    Or on a gaseous giant planet and floated in the upper atmosphere.
    Or silicon based life, on a hot planet.
    What kind of challenges would we have developing the technology we take for granted ?

    The silicone based life on a hot planet, organo-metallic based organisms might be more likely, but we know so little about what that might be like it's limitations are totally unknown..   


  15. 15 minutes ago, swansont said:

    You might notice that the only critique directed at the Mckendree Cylinders was that they are unproven.

    It's almost like you haven't read my objections. Jupiter is inside the solar system.

    Now all you have to do is some kind of analysis. Without it, this is just hand-waving. "Then a miracle occurs" of Sidney Harris fame.

    I mentioned in another thread that to get a mass M up to a speed v and stop it again requires a minimum of Mv^2 of energy, and in likelihood many times that. Decelerating to take on volatiles is a much more complex scenario than you are acknowledging. I doubt you would do that with the main ship; M is very large, and therefore the energy cost would be, too.  That raises the lower limit of how big and complex a system you need to build.

    At the very least this limits you to not trying to retrieve volatiles unless you encounter a rock of some minimum size, because it would cost more resources than you would gain.

    And my point, yet again, is that "Last gas for 1 light year" is not a problem you can deal with if you can e.g. only go 0.001 LY between refueling.

    IOW, your RV can go 500 miles on a tank, but you are trying to travel all the way across Europe and Asia on a route with no gas stations. Stop treating the latter half of this problem like it's a triviality. You skirt around this every time I point it out.

    You keep assuming we are only talking about interstellar space. This would have to start inside the solar system, be perfected inside the solar system. In fact I would think millions of these things would be build inside the solar system for use inside the solar system before the tech developed to allow longer voyages. 

    McKendree cylinders might be unproven but there is no reason to think they could not be built


  16. 21 hours ago, swansont said:

    You were the one who said full (pace is full of the stuff we need to live), so you need to define it and provide a reference, and we are talking about interstellar trips. My objection is that we have not yet gone to Mars, and undtil we have, there is no hard data that longer trips are possible.

    And therein lies the problem. You cannot have slow expansion. You have to have something at each destination. 

    It's like going into the desert — your endpoint of the trip has to be an oasis. Or on the ocean — the endpoint has to be land. You can't go 1 km a year into the ocean to get across it. 

    McKendree cylinder represents an unproven technology, and we have never, ever demonstrated a small number of people surviving on their own, in isolation, for any length of time anywhere near to what is required, regardless of the size of their cupboard. Biosphere-2 failed pretty quickly, and the ISS gets resupply on a fairly short interval. Submarines aren't an apt analogy, because they can easily make water and air, but even then, they will run out of food. In space, any mass you want to bring with you has a fuel cost, which, in turn, increases the fuel cost.

     

    If the point was colonization of space using the resources contained there there would be no destination. Your habitat would be your home and volatiles can be stored on board, even a smallish Mckendree cylinder of five miles long and one mile think would have nearly 8 square miles of living space, twice that if you could your counter rotating partner cylinder and no attempt at simply simply letting natural processes would be like the biosphere project. The biosphere project assumed no way to add outside materials and it was far too small. At first these habitats would stay inside the solar system near sources of raw materials but as technology advanced I would bet cylinders and even support tech would move out into interstellar space, using EM capaults to send volatiles to passing habitats.

    Any largish object would become a refueling station, repair, station and a place to make more habitats.  


  17. 13 hours ago, swansont said:

    Oort clouds are as yet unconfirmed and even if the do extend that far,  this does not claim they fill space. So you could still find yourself going LY stretches not inside them.

    interstellar objects do not fill space.

    the third link quotes a density a million times smaller than my example.

    If you can find data telling how often you might find a more massive object, please share it.

    But I’m guessing you don’t want to encounter one, because they would be hard to detect and hitting it will ruin your day.

    Are you simply allergic to providing citations?

    I gave a link to Mckendree Cylinders, lots of variations, take two counter rotating cylinders, energy via controlled fusion, make them 10 miles long 2 miles thick. rotate them within a non rotating metal scaffold, cover the scaffold with the construction debris. Things like rock, ice, regolith and minerals that contain other valuable materials. as thick or massive as you are willing to have if you have to slow down any acceleration you may have planned. 

    You might decide to stay hear where your house was built, say Jupiter's lagrange points, but most would eventually decide to move out, very slowly at first, building up speed with gravitational assists when ever possible.

    A huge amount of fuel, hydrogen, can be stored in the construction debris layer as ices which would protect from small meters.Keep you speed low so that when you detect an object ahead you can decelerate to take on volatiles if needed but using this method you should be able to cary many times the mass of volatiles you would lose over the time it took to semi drift to the next oort cloud.

    The only analogy we might make it RV travel, taking your home with you, it might take a million years but eventually things like gas stations might pop up on widely separated objects and chucks of icies or other necessities could be EM accelerated to the speed of the space RV to be captured so they don't even have to slow down.

    14 hours ago, swansont said:

    Oort clouds are as yet unconfirmed and even if the do extend that far,  this does not claim they fill space. So you could still find yourself going LY stretches not inside them.

    interstellar objects do not fill space.

    the third link quotes a density a million times smaller than my example.

    If you can find data telling how often you might find a more massive object, please share it.

    But I’m guessing you don’t want to encounter one, because they would be hard to detect and hitting it will ruin your day.

    Are you simply allergic to providing citations?

    https://en.wikipedia.org/wiki/Stanford_torus

    https://en.wikipedia.org/wiki/O'Neill_cylinder

    https://en.wikipedia.org/wiki/McKendree_cylinder

    https://en.wikipedia.org/wiki/Dyson_sphere#Dyson_swarm

    https://en.wikipedia.org/wiki/Space_habitat

    Best I could do on short notice, now I have go and pass some more kidney stones hallelujah!!!!! 


  18. 3 hours ago, swansont said:

    Citation needed

    https://phys.org/news/2018-08-oort-clouds-stars-visible-cosmic.html

    https://en.wikipedia.org/wiki/Interstellar_object

    http://www-ssg.sr.unh.edu/ism/what1.html

    A cursory look only found listings of objects like oumuamua and or gas and dust but I have recently seen estimates of smaller ice and rock objects occuring in interstellar space, enough to be useful but I can't find them right now. I am unable to be online for long due to heath problems. I'll continue to look for the specifics at later date or with draw my claim your call...   

    7 minutes ago, swansont said:

    For the love of...

    Will you PLEASE provide a citation for this claim? 

    The interstellar medium has about 10^6 atoms per cm^3 (mostly Hydrogen. Some Helium. A smattering of heavier elements) as a maximum. Minimum is much smaller.

    https://en.wikipedia.org/wiki/Interstellar_medium

    If you have better information, provide a link to it

    Now, what does that mean. That's 10^12 atoms per cubic meter. Sounds like a lot. We put a 1 square meter scoop on our craft and collect everything. We go really fast: 1000 km/s, or 0.01c (we'll ignore all the problems associated with going this fast)

    That's 10^6 m/s, meaning we collect 10^18 atoms per second, once we're going that fast. It takes us a week (6 x 10^5 s /86400 s/day = 7 days) to harvest Avogadro's number of atoms. A gram of hydrogen per week. And only if we go really, really fast.  

     

     

    You do realise you are quoting an average of gas not objects right? And the oort cloud extends almost a light year away from the sun at least? 

    3 hours ago, Bufofrog said:

    I really think you are minimizing the incredible difficulty in making your own little world that flies around space!

    "your own little world" would be many miles long and miles wide, rotate for internal gravity and house thousands of people. The asteroids would be the construction materials along with trojan asteroids, kuiper belt objects and or oort cloud objects. I'm not saying it would be easy but the task is well within the realm of possibility. Engineering studies were done decades ago.  


  19. 2 hours ago, swansont said:

    I've seen arguments that take a distance and argue that there is this very small speed that expansion requires, but the problem with that is it ignores the discrete nature of the travel. There is no place to stop and resupply in the middle of nowhere. It's not a matter of only going some speed. It's a matter of surviving until you get to the next habitable planet.

    You can argue it took 10,000 years to expand across the ocean to the new world, and that's 10,000 km (just for sake of argument), so the speed was just 1 km/year, but you don't just go 1 km out into the ocean that first year. At the very minimum you have to go to the next island.

     

    Again, I'm not convinced this is true. It's just an assertion. Not an actual argument.

     

    The situation is more akin to being able to refuel and build more boats as you go. Even tiny islands would be exploited to refuel, repair, and reproduce more boats.

    We used to think the asteroids were natural islands for resources of a kind but volatiles would be a problem now we know that asteroids contain volatiles. We used to think that metals were the limit but we now think that carbon fibers and such will be the majority of construction materials with metals having a much smaller role. We used to think that self contained habitats were a necessity but now we know that ices and other volatiles are available in space. Space is not empty, gas dust and even chucks exist in reasonable numbers even in interstellar space. 

    It's not a matter of building a ship to travel to the new world, its a matter of colonizing the ocean by removing the raw materials we need form the water. Oort clouds extend far from a star and do not suddenly stop but slowly become the interstellar medium, which is not a vacuum but contains significant quantities of various materials from the size of dust grains to planetoids. 

    The expansion would proceed from the asteroids to the kuiper belt to the oort cloud to oort to objects in the interstellar medium to other oort clouds and onward. Planets and deep gravity wells would be avoided for the most part.

    Single forays to the next star would be difficult to improbable but tiny steps out by millions of habitats would be inevitable...  

    1 hour ago, swansont said:

    You were asked for supporting evidence. Saying, in effect, "Go dig it up yourself" isn't really an acceptable response, especially in light of it being in the context of things that nobody has ever done.

    If no one had ever used iron ore to make cars how would you even know there is supporting evidence? he was as much as saying there are no raw materials and so it can't be done. Do I really have to demonstrate the existence of resources in space? 


  20. 5 minutes ago, Bufofrog said:

    I really think you are minimizing the incredible difficulty in making your own little world that flies around space!

    I suggest you do some research...  Your assertion still sounds like someone standing on an iron ore deposit and says it's impossible to use it to make cars... 

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