Question

Firstly, I understand that we have no observational evidence for 'wormholes'. They are theorised solutions to general relativity equations.

That said, if macroscopic wormholes do exist---how do they work? I've been thinking about this for the past couple of days, and I have some questions.

What does the mouth of a wormhole look like? I've seen this; is that more or less accurate?
If I place one end of a wormhole in a high magnetic field, and the other end on my desk, will all my ferrous objects fly into the wormhole?
If so, with what force? What does the magnetic field look like at each end of the wormhole?
If the distance between the mouths of the wormhole was comparable to the force that the magnets exert, would the magnet 'pull' on itself and draw itself into the wormhole?

Do any of these questions even make sense?

Answer 1

I am not an expert by any means (just starting my studies in these topics) but i will share my understanding of the topic so to complement any further discussion of your question:

1) The example of joining two points in a sheet of paper makes good intuition but i think its physically very misleading; there is no such operation in GR as joining two space-time points, because in the case of the sheet of paper the points are joined by being close in an embedding space (euclidean 3-dimensional space), while classical GR does not have any notion of an embedding space in which space-time exists. Other theories (not sure, but probably string theory?) may have further assumptions in this regard, but as far as i can tell, such embedding spaces are not allowed to produce any direct, physical consequences

2) GR allows solutions in space-time topologies that are non-trivial (where trivial means homeomorphic to asymptotically flat minkowski space), but the dynamics of GR doesn't allow by itself any dynamical transition between space topologies.

What there exists in the literature is postulating ad-hoc the geometry in question, in this case two asymptotically flat minkowski spaces connected by the identification of two mouths on each space. Then one uses GR equations to derive the required tensor that makes the geometry stable.

What there is not in the literature to my knowledge is taking flat minkowski space, and obtain a consistent evolution of trivial, flat space topology in a given time foliation parametrized as t0 into another non-trivial space topology in another time , even assuming exotic stress-energy densities, i.e: . And the reason is that GR as a dynamical theory, is strictly a local theory (please, correct me if this is wrong, this just represents my knowledge of the subject) and as a local theory, doesn't really tell much about how the manifold behaves globally