3 ms·
You can just as easily have a Newtonian space with time travel (roll up the time coordinate in a circle by identifying T=0 with T=1). I think the same trivial c
by cousin_it 8y ago
You can just as easily have a Newtonian space with time travel (roll up the time coordinate in a circle by identifying T=0 with T=1). I think the same trivial construction would work in GR, so you don't need mass, rotation, etc. That doesn't seem to prove anything about the nature of time. Does anyone have a copy of Gödel's article so we can see if the argument goes deeper?
- nabla9 8y agoOf course it's must deeper than that. http://kurtgoedel.de/cms-83FO/wp-content/uploads/2016/10/Goedel.pdf http://kurtgoedel.de/cms-83FO/wp-content/uploads/2016/10/Goe... It's a solution allowed by GTR, not a new trick definition. It belongs to the family of 'dust solutions'. You arrange particles (can be as big as galaxies) that move in certain way and you get time travel. Only other assumption is nonzero cosmological constant. You can't get time travel in Newtonian universe just by arranging objects in it to move certain way. In general, closed timelike curves are allowed in GTR. It's possible generate them several different ways. Gödel just made super elegant one. What GTR allows and what actually is allowed are different matters. Just like Newtons equations break at some extremes, same probably happens to GTR.
- cousin_it 8y agoI see. Thanks for the link!
- gradschool 8y agoIf two trains are heading toward each other on the same track, one way for momentum to be conserved is if they pass through each other. Even though that's not what we observe in the real universe, its existence as a mathematical solution implies that mass is an illusion. How is this argument different from Godel's?