From: runningman@writeable.com   
      
   On 21/02/2024 00:12 Sylvia Else  wrote:   
   > On 21-Feb-24 8:31 am, The Running Man wrote:   
   >>> On 2024-02-20 1:51 p.m., The Running Man wrote:   
   >>>>> For some reason, the PNN folks who were quite active on this group do   
   >>>>> not seem to have posted anything in a long while. Did they run out of   
   >>>>> active people, or money? Or did they finally figure out it doesn't work   
   >>>>> and quietly closed shop?   
   >>>>> --   
   >>>>> /* * * Otto J. Makela  * * * * * * * * * */   
   >>>>> /* Phone: +358 40 765 5772, ICBM: N 60 10' E 24 55' */   
   >>>>> /* Mail: Mechelininkatu 26 B 27,  FI-00100 Helsinki */   
   >>>>> /* * * Computers Rule 01001111 01001011 * * * * * * */   
   >>>>   
   >>>> What does PNN stand for?   
   >>>>   
   >>>   
   >>> It stands for Propulsione Non Newtoniana (Italian, meaning Non-Newtonian   
   >>> Propulsion). A group of Italian people claiming that they have a   
   >>> propulsion system using no reaction mass. Something like a microwaves   
   >>> bouncing around in a closed cavity that they claim, without explaining   
   >>> the physics behind it, that it produces acceleration. They have video   
   >>> showing that it gives if I recall correctly some 200 mN of force. We   
   >>> tried to explain to them that because their microwaves heat one side of   
   >>> their apparatus more than the other side, the air is heated more on one   
   >>> side than the other. This differential in air temperature can explain   
   >>> the force that they measure, therefore, outside an atmosphere it   
   >>> wouldn't work. But they don't want any of that, they are sure that their   
   >>> "invention" will revolutionize rocketry.   
   >>>   
   >>>   
   >>> Alain Fournier   
   >>>   
   >>   
   >> I once read a (fiction) book about futuristic spaceships and they claimed   
   that a mass-less propulsion drive could be made by a huge electromagnet which   
   would change its polarity so fast that the EM flux didn't have time to   
   dissipate, thereby creating    
   a repelling force.   
   >   
   > Transmitting electromagnetic waves using a directional antenna produces   
   > a net force. Not much of one, for sure, but some. It's a kind of photon   
   > drive.   
   >   
   > But it's still not mass-less, because the photons that form the   
   > electromagnetic waves have mass, and the attached craft is losing mass   
   > in proportion to the energy being radiated.   
   >   
   > Near a star, the required energy can be collected using solar panels,   
   > but solar sails of the same area work better.   
   >   
   > So there's a reason we don't use photon drives.   
   >   
   > Sylvia.   
      
   The idea was that the repulsive force would come from the EM field and not any   
   photon mass ejection.   
      
   Photon mass ejection from an antenna would be similar to a solar sail, I   
   imagine.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)