From: kozelsm@yahoo.com   
      
   On Friday, October 23, 2020 at 9:40:07 PM UTC-4, Alain Fournier wrote:   
   > On Oct/23/2020 at 21:08, JF Mezei wrote :   
   >     
   > > Another aspect I heard, but I am not certain and that when they buildt   
   > > the Gothard tunnel in Switzerland, one challenge was heat. Apparently   
   > > the weight (as in force, not mass) of mountain above was so great that   
   > > the pressure against matter causes the rock to heat up.  If that is   
   > > true, that would be another example where gravity constantly acts on   
   > > matter to release some form of energy (in this case heat).   
   >    
   > I'm not familiar with the boring of the Gotthard tunnel and I'm not sure    
   > about heating related to that. But compression from mass can generate    
   > heat. Some part of the heat in Earth's core comes from that. But it    
   > isn't some kind of magical perpetual heat that comes from nowhere. If    
   > gravity compresses a mass of rock, that generates heat. But as the mass    
   > of rock becomes more compressed, it becomes harder to compress it more    
   > and the process will eventually stop. So if the rock over the tunnel    
   > squished the rock on each side of the tunnel by say 1 mm, that would    
   > generate great amounts of heat. But once that squishing is done, it's    
   > done. The heat generated will dissipate. It will take time because    
   > dissipating heat through hundreds of meters of rock takes a lot of time.   
   >    
   > There is also heat in the tunnel that comes simply from the fact that    
   > there is a lot of heat below (Earth's core) and lots of insulation above    
   > (a mountain).   
      
   Closer to the mantle of the Earth, where temps gradually increase with depth.   
      
   The temps in the Gotthard Base Tunnel are not that much higher.  45°C or    
   113°F.   
      
   "Inside the tunnel they measured a high of 45°C, far above the safety limit   
   of    
   28°C laid down by the Swiss workplace accident insurer."   
      
   https://www.swissinfo.ch/eng/alptransit_engineers-meet-challenge   
   of-gotthard-tunnel/40792690   
      
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