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Relativistic Kill Vehicles and the Fermi Paradox

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  • #76
    Originally posted by WABs_OOE View Post
    It's getting to the solar system that is the problem. Not hitting the planet itself. If the solar system travels a predictable path, ie didn't run into some major black holes that would alter it's course, then you can reasonably get your asterioid into the general area. After that, you can use onboard intelligence to deploy reflective surfaces to use solar winds to guide you onto target.
    Possibly but you also have to allow for the vagaries of random chance. You can compute a course that will avoid significant gravitational deflections (you might even be able to use them to your advantage). The question is how do you cope with random influences like micrometeorite impacts, galactic gas/dust effects and radiation pressure - which as you noted generates force.
    Last edited by Monash; 14 Apr 18,, 08:08.
    If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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    • #77
      Originally posted by Monash View Post
      Possibly but you also have to allow for the vagaries of random chance. You can compute a course that will avoid significant gravitational deflections (you might even be able to use them to your advantage). The question is how do you cope with random influences like micrometeorite impacts, galactic gas/dust effects and radiation pressure - which as you noted generates force.
      Well, yes and no. For the centre of the galaxy, you're absolutely right but life as we know it could not exist there but out in the arms, it's mostly space. They would know the source of such particles, ie stars and predict the likelyhood of such impacts. It's the same reason why we can go through the Asteroid Belt to get to Mars. It's mostly space.

      It's the unseen black holes you have to worry about.

      Edit: This got to be the nerdiest thread on WAB.
      Last edited by Officer of Engineers; 14 Apr 18,, 17:14.
      Chimo

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      • #78
        Originally posted by WABs_OOE View Post
        Edit: This got to be the nerdiest thread on WAB.
        Mea culpa. :-)

        Nerdy can still be interesting though.

        BTW, this video is a must-watch:

        https://www.youtube.com/watch?v=NFTaiWInZ44
        Last edited by Ironduke; 14 Apr 18,, 23:10.
        "Every man has his weakness. Mine was always just cigarettes."

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        • #79
          Originally posted by WABs_OOE View Post
          Well, yes and no. For the centre of the galaxy, you're absolutely right but life as we know it could not exist there but out in the arms, it's mostly space. They would know the source of such particles, ie stars and predict the likelyhood of such impacts. It's the same reason why we can go through the Asteroid Belt to get to Mars. It's mostly space.
          The big stuff yes, it's the little stuff that's the killer in terms of accuracy over long ranges (think hundreds/thousands of light years). You could infer or even detect asteroids belts and other major obstacles but random micrometeorite impacts or solar flares? The cumulative effect of these kind of events would be critical to any mission based on a 'simple' ballistic calculation. IMO you would have no chance without a onboard navigation system and some kind of drive to make course corrections. ... and yes, this is as 'nerdy' a thread as I have ever seen on WAB. What can I say except 'nerds rule'.
          If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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          • #80
            Originally posted by Monash View Post
            The big stuff yes, it's the little stuff that's the killer in terms of accuracy over long ranges (think hundreds/thousands of light years). You could infer or even detect asteroids belts and other major obstacles but random micrometeorite impacts or solar flares? The cumulative effect of these kind of events would be critical to any mission based on a 'simple' ballistic calculation. IMO you would have no chance without a onboard navigation system and some kind of drive to make course corrections. ... and yes, this is as 'nerdy' a thread as I have ever seen on WAB. What can I say except 'nerds rule'.
            Something what you said. There is no way for that asteroid to make it one straight line trip from home to target. Sooner or later, they have to pass through other star systems. Why wouldn't the aliens do what we do? Use large gravitational source as sling shots? We use planets to hurl VOYAGEUR and PIONEER out. Why would not aliens do the same with star systems? Aim the asteroid at the nearest star. Find suitable planets. If found, crash. If not, sling shot around the star to the next star system and so on and so on.
            Chimo

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            • #81
              Yes, they would have to sling shot, if only across the outer 'edge' of various stellar gravity wells. Trouble is the more systems they pass by/through the greater the effect those systems will have on the asteroid. It will get hit by random debris and solar radiation so course corrections seem inevitable.

              Hollowed out asteroids would be good candidates for survey missions though.
              If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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              • #82
                Originally posted by Monash View Post
                Yes, they would have to sling shot, if only across the outer 'edge' of various stellar gravity wells. Trouble is the more systems they pass by/through the greater the effect those systems will have on the asteroid. It will get hit by random debris and solar radiation so course corrections seem inevitable.
                But wouldn't course correction be the case when slingshotting out of the system? The AI to decide to crash would have to course correct to hit a planet. It could just as easily use its reflective surfaces to plot a course to slingshot to the next star system.
                Chimo

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                • #83
                  Yep, but as I originally interpreted the proposal it was that aliens could launch a 'dumb' asteroid and rely on extremely sophisticated math calc and ultra-precise astronomical measurements to calculate a purely ballistic path from A to B. Across thousands of light years!

                  My point was that you might (at least over the first few systems) be able to calculate the approach to a target star so that the you use its gravity field to curve it round towards the next target. It would mean you have to make accurate measurements of the rate of solar rotation and the strength of a target stars the gravity fields etc in advance of launch but in theory it is doable.

                  But what you couldn't do is calculate the effect of any specific meteorite impacts etc during the trip because they would be impossible to predict in advance. You might be able to calculate a probability curve for impacts over the course of centuries but what you couldn't do is predict the effect any single hit would have. This is because each individual impact is a random event in terms of it's mass and direction.
                  Last edited by Monash; 17 Apr 18,, 12:55.
                  If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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                  • #84
                    Originally posted by citanon View Post
                    Now you take that probability, and put the following conditions onto the 100 billion to 500 billion starts in our galaxy:

                    1: not in the galactic core
                    2: Sun like
                    3: has planets orbiting in the habitable zone
                    4: is sufficiently stable to not fry habitable planets with solar flares
                    5: does not have other unfavorable astronomical calamities going on in its neighborhood

                    Finally, out of all of the above, if intelligent life emerges, is it technological life? What if you had an ocean world with very smart alien dolphins who have no use for technology what so ever? Seems like the chances of intelligent technological life existing at the same time within a million year time span might be quite small.
                    I'm not an astrophysicist, but from my layman's understanding, a red dwarf seems like it would be an ideal place for life to evolve, with a lifespan measured in the trillions of years, and a constant temperature and stability. From what little I know, a planet would need to orbit much closer to a red dwarf than a yellow dwarf like our Sun. Potential downsides I see for life evolving on a planet orbiting a red dwarf would be the potential for the planet to be tidally locked to the star, and also that a red dwarf may be perhaps too stable and consistent, and not give impetus toward accelerating the evolutionary process that a more variable yellow dwarf would.
                    Last edited by Ironduke; 01 Jul 18,, 16:25.
                    "Every man has his weakness. Mine was always just cigarettes."

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                    • #85
                      Red drawfs tend to have fluctuations in their output that cause issues for a potentially habitable planet. Intense radiation from a star can basically blast the atmosphere off a planet. It is suspected that this is what happened to mars, and that the earths magnetic field (gifted to us by the metallic core) is what has allowed the earth to retain atmosphere for this long. It's likely that a magnetic field is a precursor to an environment stable enough to develop life.

                      Getting back to the original topic, it seems to me most any ship capable of a trip duration that we would consider survivable time frame would basically be a weapon. Even accelerating a modest mass, say 1000-3000 tons, at 0.01g consistently would add about 1%c per year and give you impact measured in gigatons at the arrival point in only a half dozen light years. A probe specifically designed to gravity assist rather than slow down so as to investigate multiple star systems would be indistinguishable from a weapon designed to devastate a biosphere.

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                      • #86
                        Saw an interesting article recently. I was going to reactivate an old zombie thread that was relevant but I decided just to post it here instead;

                        In short DARPA has provided a (small) grant to study the maths behind what is posited to be a potential reactionless drive which in theory would operate on similar principals to the one Dr Woodward at NASA is currently conducting bench tests on. Here is the link to the article;

                        https://www.plymouth.ac.uk/news/scie...for-spacecraft

                        Roger Sawyers work on what he calls his 'EM" drive has of late been widely criticized in scientific circles both because it failed independent tests and because the 'theory' he proposes to explain how it works is apparently a washout. It doesn't help that Sawyer has made some very ambitious claims about progress. However Dr Woodward proposes a different theory derived (I think) from MOND theory that explains why his idea might work. Unlike Sawyer as far as I am aware to date Dr Woodward has not any bold claims about his 'drive' and so far NASA is still backing his work.

                        So its interesting to see these ideas still have enough credibility to get seed funding from scientifically credible organizations. Fingers crossed.
                        Last edited by Monash; 23 Sep 18,, 02:33.
                        If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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                        • #87
                          IMO, it has less to do with credibility and more to do with the incredible pay out if any of these ideas panned out. Kinda like the CIA and remote viewing and their other psi warfare studies: probably bullshit, but you can't afford to not follow up and confirm it is bullshit because of the repercussions if the bullshit proved to be true. As such I don't blame them for contributing a small amount of resources to the idea to test if it is remotely plausible. That is kinda what DARPA is there for.

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                          • #88
                            Originally posted by Ironduke View Post
                            I imagine our sense of smell would get better, our jaws would again grow large enough to fit our wisdom teeth, our vision would improve, spatial intelligence would return, etc.
                            As long as we have dogs, our sense of smell is going to remain effectively non-functional. Man-dog is a symbiote, we evolved together. Man predog had a larger olfactory bulb. We gave it up for better problem solving. We gave up about 15% of brain mass. Dog gave up problem solving and about 25% of brain mass. Every species including us subject to domestication has a smaller brain than the pre-domestication version.

                            You're right though when you implied that outward physiological changes would not occur in these sorts of timeframes.
                            To an extent. but diet can have a profound effect. Grain/carb, lean protein based survival breeds smaller physiques that a red meat fat rich diet.

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                            • #89
                              Originally posted by zraver View Post
                              To an extent. but diet can have a profound effect. Grain/carb, lean protein based survival breeds smaller physiques that a red meat fat rich diet.
                              I have read articles pointing out that the consumption of animal protein - in the form of red meat/marrow scavenged from carcasses would have aided the development of larger brains in early hominids because of the relative abundance of proteins and fats in this food source.
                              Earlier species were already heavily vegetarian so it was the progression to an omnivorous diet that is argued in these articles as having made the difference.

                              Picking up rocks to crack open bones and sticks/stones to throw at encroaching hyenas/vultures/carnivores did the rest.
                              If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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                              • #90
                                Originally posted by Monash View Post

                                Picking up rocks to crack open bones and sticks/stones to throw at encroaching hyenas/vultures/carnivores did the rest.
                                The three evoluntionary break throughs that created us were fire, tools and dogs. Man before dogs is just a member of our family tree, man after dogs is us. Ever wonder why we like puppies, why babies like stuffed animals, why dogs are so attuned to us? We evolved together.

                                https://www.theatlantic.com/technolo...rthals/257145/

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