He did not, when he wanted to compute the geometry of his continuum. But once he formulated, it realized it is pure geometry. Without mass, it would be just another geometry.
Because the gravitational field provides negative energy. And the two things seem to compensate themselves out precisely. A positive mass induces a negative gravitation and the total is zero. At least as long as spacetime is flat at large scales, as it seems to be. This is actually how mass assumes its permanent character. It needs to generate an offsetting negative energy in order to keep the balance happy.
So, it would be incorrect to speak of creation ex-nihilo, since we are still are, nihilo. In a sense.
Spacetime is a 4 dimensional manifold endowed with a covariant 2nd rank pseudo Riemannian metric tensor field. Translation: a 4 dimensional surface in which the distance between two nearby points can have a negative squared distance. If the squared distance were always positive, it would be a Riemannian surface, not a pseudo Riemannian one.
And this tensor field, ergo the operator that allows to measure distances between two nearby points, is affected by energy, ergo matter. So matter influences it, it does not necessarily originate it.
GR, In a nutshell, so to speak.
I subscribe to the B-series theory of time. Aka the block Universe, on account of relativity and the geometry of the universe. Therefore, I reject the idea that the past stopped existing. So, no. I did not have a beginning. My past self is still there, an event on that 4 dimensional surface. And my death is already there, as well. At another location on that surface.
I do not use tensed verbs when addressing events on the Universe, in general.
Yes, it is absurd. Space expands in time, at least from our vantage point. But that is a far cry from claiming that spacetime expands. Spacetime cannot have any dynamics whatsoever, For, within what does it expand and at what rate? There is nothing outside of it that can be used to measure its expansion and the rate thereof.
Causality makes sense only when you have a time context in place and a well defined arrow of time. Ergo, in Universes which are not in thermodynmical equilibrium. Which should be clear if we think that time dirctionality is a macroscopic effect deriving from entropy unbalance. Ergo, you need something macro, before you can talk about it. There is no time arrow in fundamental physics. Therefore, causality makes sense only withing such universes, and to apply it to the contexts in which it is defined, is logically unwarranted.
Ciao
- viole
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