3 ms·

There is one thing not relative in Einstein's universe: The universe centre of mass.

• gress 13y ago
  How is that not relative to the motions of all of the other masses in the universe?
  • 3pt14159 13y ago
    Good question. Say you spin like a ballerina in a circle, that force that pulls up your arms (angular momentum / centrifugal force). But why should your arms go up? If you take the person's face's point of view, the arms are still and some mysterious force is pulling them up. This is because it is relative to the CoM and spin of the universe itself (although things get a bit wonky when we look at this even closer).
• jerf 13y ago
  However, in the face of inflation that can still end up ill-defined, requiring measurements that can not be taken from the inside. And recall that while the specific inflation that our universe actually experienced may not fit directly into Einstein's original equations, a "cosmological constant" that permits a certain type of inflation does exist.
• pdonis 13y ago
  The universe doesn't have a center of mass.