3 ms·
> The universe, despite being filled with mass and energy, is roughly flat. No, it isn't. It is spatially flat (if we choose appropriate coordinates), but the
by pdonis 5y ago
> The universe, despite being filled with mass and energy, is roughly flat.
No, it isn't. It is spatially flat (if we choose appropriate coordinates), but the spacetime of the universe is not flat, because it is expanding.
The rest of your reasoning is wrong because it starts from this false premise.
- whatshisface 5y agoWhich kind negative curvature does the drive need?
- pdonis 5y ago"Negative curvature" isn't quite the right term. (For one thing, curvature in 4-dimensional spacetime cannot be described by a single number.) The Alcubierre drive requires "exotic matter", i.e., matter that violates the weak energy condition. One way of phrasing that condition is that the matter will have negative average energy density as measured by certain observers.
- pdonis 5y ago> Which kind negative curvature does the drive need? The issue with your reasoning is not what kind of curvature the drive needs, but the idea that there is a "natural" bending of spacetime at all. There is no such thing.