3 ms·

"most of the universe's galaxies are already receding faster than the speed of light" Relativity theory: "It's impossible to go faster than the speed of light"

• goatlover 5y ago
  The expansion of space doesn’t fall under that limitation. Spacetime isn’t a particle or collection of particles. It’s the gravitational field.
  • mrphoebs 5y ago
    Space-time isn't a gravitational field. Gravitational fields curve space-time.
    • goatlover 5y ago
      Well, that might be a matter of interpretation: "I point out that the often voiced claim that in the general theory of relativity (GR) geometry and gravity are ‘associated’ with each other can be understood in three different ways. The geometric interpretation asserts that gravity can be reduced to spacetime geometry, the field interpretation claims that the geometry of spacetime can be reduced to the behaviour of gravitational fields, and the egalitarian interpretation affirms that gravity and spacetime geometry are conceptually identified." https://www.sciencedirect.com/science/article/abs/pii/S1871177408000053#:~:text=as%20the%20discovery%20that%20spacetime,positions%20rather%20than%20single%20positions https://www.sciencedirect.com/science/article/abs/pii/S18711....
• zamadatix 5y ago
  Expansion isn't objects in space moving farther apart through space it's the change in the geometry of space itself. A poor analogy might be a continuous zoom of a map map on your phone while something always moves less than a constant speed limit of pixels per second on the screen. It is easy to see this object can move around locations on the map but may not be able to reach most of the map if it is zooming in fast enough that far away portions !at get farther away faster than it can travel to them at the constant pixels per second.
  • koonsolo 5y ago
    Wow yeah, thanks for the explanation. Now I kind of get it (still, relativity theory is hard to comprehend for me).