From: eripe.dk@gmail.com   
      
   On Monday, January 23, 2017 at 11:49:31 AM UTC+7, nu...@bid.nes wrote:   
   > On Sunday, January 22, 2017 at 5:14:36 PM UTC-8, eripe wrote:   
   > > On Monday, January 23, 2017 at 3:45:07 AM UTC+7, nu...@bid.nes wrote:   
   > > > On Sunday, January 22, 2017 at 5:41:14 AM UTC-8, eripe wrote:   
   > > >    
   > > > (zeppelins filed with x, where x is lighter than hydrogen)   
   > > >    
   > > > > I have an idea, Diz iz Zuper Nutz; you could fill it with photons. If   
   you   
   > > > > have a perfectly reflective inner side, the pressure from the light   
   would   
   > > > > keep it inflated with a vacuum inside.   
   > > >    
   > > >   The reflector would only have to be perfect at one wavelength.    
   > >    
   > > Do we need Doc-Smithian technomacis Perfect Reflector fields, or will   
   > > suitable stacked coatings do the trick?   
   > >    
   > > I have no idea what any of those words mean :P   
   >    
   >   Uh, I misspelled "technomagic".   
   >    
   >   E. E. "Doc" Smith wrote gee-whiz SF with lots and lots of specious   
   "superscience" including some sort of field effect that when applied to a   
   metal would make it an absolute perfect reflector of EM radiation. One thing   
   he used it for was to build a    
   sort of ray gun- mill a paraboloid cavity into one side of a block of metal   
   and inject atomic oxygen and strongly ionized nitrogen at the focus. The gases   
   would emit lots of UV (which metals ordinarily absorb really well) while   
   combining and the    
   paraboloid would focus it to a beam. Replace the block with a sheet and you   
   could gently tweak the curvature to focus the beam to a point which would burn   
   through pretty much anything at fairly large distances.   
   >    
   >   (BTW with that last trick he predicted what we now call "adaptive optics".)   
   >    
   >   As for coatings I was thinking of the selectively absorptive and   
   reflective coating on frinst binocular lenses, but arranged to *enhance*   
   reflection rather than prevent it.   
   >    
   > > > > Radiation P = 0,5*p*c   
   > > > > P = 0,5 * 1E5 Pa * 3E8 m/s = 15E12 or 15 TW/m2.   
   > > > >    
   > > > > Im not sure how to calculate how much energy must be fed in there to   
   build   
   > > > > that pressure up. Say the mirror is 99,999999999 % reflective, then you   
   > > > > have to supply 15 W/m2 to make up for the losses at 15 TW/m2. I suppose   
   > > > > that much light would inflate it then, but how long would it take?   
   > > > >    
   > > > > Once you know the energy, you can find the mass from E = m c^2   
   > > >    
   > >    Also, if the envelope is controllably deformable, it's an EMdrive!   
   > >    
   > > This would explain how those space faring blimbs work on   
   >    
   >   Mmm... I forgot- to make an EMdrive it needs an absorber at the narrow   
   end. Allow for changes in the reflectivity of the internal coating maybe under   
   the localized influence of another frequency of light?   
      
   But if we can get this good reflection (= a Quality factor of a trillion)   
   working in the EM drive, I doubt you would use balloons. Just replace the   
   wheels of your car with a tapered bucket.   
      
   >    
   > > Anyway, was thinking a bit more about the amount of energy needed.   
   > > So if the ship is 60 meters wide, that means in one second a photon will   
   > > bounce c/(2*60)=694 times of one side of the ship, so my 15 W/m2 input   
   > > becomes 10400 W/m2.   
   >    
   >   It has to support itself against varying air pressure at different   
   altitudes. What to do when you want to go up or down, vent light to drop   
   altitude or absorb and store it somehow? As for gaining altitude, you'll need   
   to carry some very powerful    
   lasers aboard.   
      
   If it was a (sufficiently advanced) one-way mirror, the sun could help provide   
   the filling (not sure how much of it would fit the narrow frequency band), and   
   then you just vent the surplus, or point it at the enemy. You would only need   
   a laser at night,    
   perhaps deflate and hide?   
      
   >    
   > > I need to get to 15E12, so it will take 15E12/10400 = 400 hours to inflate   
   it   
   > > with 15 watts/m2, with perfect reflection. 15 W in 400 hours is 21,6 MJ/m2,   
   > > is basically zero mass added. Also not too terrible in regard to blowing   
   up.   
   >    
   >   It's not likely to blow up, but battle damage could rupture the envelope,   
   making it a briefly extremely bright light source.   
   >    
   > P. S. In the previous post I accidentally used a nym I invented for use   
   elsewhere. Sorry for any confusion.   
   >    
   >    
   >   Mark L. Fergerson   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)