From Newsgroup: rec.arts.drwho.moderated   
   From Address: jameskuyper@verizon.net   
   Subject: Re: "The Angles take Manhattan" - ground transport?   
      
   On 10/07/2012 10:43 AM, eleven@fish.net wrote:   
   > In article , jameskuyper@verizon.net says...   
   >> Time travel might actually be impossible, but so long as top physicists   
   >> are seriously debating the issue, stories postulating that it can   
   >> actually be done are entirely legitimate science fiction.   
   >>   
   >    
   > Top scientists are therefore wasting their time and no doubt "public"    
   > money.   
   > "time" is an abstract concept not something you can travel through.   
   > Top scientist are therefore just writing mathematical science fantasy.   
      
   Wow. Most ordinary objects travel through time at a constant rate of 1   
   year per year - but if you were making any kind of sense, that would   
   imply that this forward time travel must also be an illusion of some kind.   
      
   With just as much (or as little) sense, I could say the same thing,   
   replacing "time" with space, thereby justifying the claim that it's not   
   possible to travel through space.   
      
   Einstein's special theory of relativity reduced the distinctions between   
   time and space, replacing both concepts with a four-dimensional   
   space-time - and that replacement ultimately led to equations that   
   describe the release of nuclear energy from a nucleus (whether from the   
   Sun, nuclear bombs, or nuclear power plants) - but that must all be a   
   fantasy - many of the people who were living in Nagasaki and Hiroshima   
   in 1945 must still be alive, and will be grateful to learn that their   
   deaths were just imaginary. The Sun going dark will, however, interfere   
   with their joy at their continued survival.   
      
   Einstein's general relativity changed space-time from an inanimate   
   background to an active participant in physics. Massive objects change   
   the shape of space-time, and the shape of space-time causes objects to   
   move in curved paths (called geodesics) even when no forces are applied   
   to them, the same phenomenon that Newton's theory of gravity explained   
   in terms of gravitational force. General Relativity can be used to make   
   many predictions about gravity that are somewhat different from those   
   made by Newtonian gravity, and many of those predictions have been   
   confirmed, none have failed.   
      
   In particular, GR predicts the existence of traveling distortions in the   
   shape of space-time called gravitational waves, which can carry energy,   
   momentum, and angular momentum. Gravitational waves are inherently very   
   weak and difficult to detect; they have not yet been directly detected.   
   However, if GR is correct, close binary pulsars should emit large   
   amounts of gravity waves. The lost energy and angular momentum should   
   cause their orbital periods to decay at a rate that can be both   
   predicted and measured with considerable accuracy. Those predictions   
   match those measurements - but that must also be a fantasy, right? After   
   all, those pulsars can't actually be shining brightly enough to be seen   
   from Earth - that would require the release of nuclear energy, which is   
   also a fantasy.   
   --    
   James Kuyper   
      
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