From: nuny@bid.nes   
      
   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?   
      
   > 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.   
      
   > 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   
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