Chris Hillman

Hi, Seele, for some reason you seem to have ostentatiously ignored several recent PF posts including Post #2 just above in which I tried to carefully warn against several serious misconceptions. This is disappointing.

It would be well to qualify that. See how I described what gtr says about various aspects of "black holes" in these PF posts (listed roughly in ascending chronological order, for my convenience in avoiding listing any post twice):

• here, comparing static observers in the Schwarzshild vacuum with Rindler observers in the Minkowski vacuum,
• here, about coordinate speeds and light cones in the Schwarzschild vacuum,
• here about light bending and instability of the "circular photon orbit" at in the Schwarzschild vacuum,
• here and here about the interpretation of the Schwarschild radial coordinate (and comparing various distinct and operationally significant notions of "distance in the large"; see also this),
• here and here about Kottler lambdavacuum (Schwarzschild with lambda) and an the stability of orbits,
• here, where I briefly describe the Aichelburg-Sexl ultraboost of a non-rotating black hole and its relation with pp-wave solutions,
• here about "mass inflation" in the Poisson-Israel model of a black hole interior, and here about black hole interiors generally,
• here, comparing various black hole models and mentioning the "teleological" nature of the event horizon,
• here and here about exact solutions of the EFE (which include the Schwarzschild vacuum, Kerr vacuum, OS dust ball, and other black models),
• here, here, here, here, and here about varous common misconceptions concerning black holes,
• here about the Oppenheimer-Snyder collapsing dust ball model,
• here about closed timelike curves inside the "eternal Kerr vacuum" model,
• here about the plausiblity of event horizons,
• here, here and here about the physical experience of various observers near/inside a black hole,
• here about "quasi-Keplerian orbits" in the Schwarzschild vacuum,
• here about "gravitational time dilation" near a black hole, and comparing de Sitter versus Lense-Thirring precession of the spin axes of gyroscopes in orbit around a (possibly rotating) black hole,
• here about locally flat spatial hyperslices in the Schwarzschild vacuum,
• here about comparing some coordinate charts on the Schwarzschild vacuum,
• here about "tipping over of light cones" (e.g. in the Kerr vacuum as often it is often graphically represented in terms of the well-known Boyer-Lindquist chart),
• here about stationary versus static spacetimes (e.g. Kerr versus Schwarzschild),
• here, about the "effective potential" governing geodesics in the exterior of the Schwarzschild vacuum,
• here about the Vaidya null dust (which can be used to model the formation of a black hole due to the collapse of a spherically symmetric shell of incoherent EM radiation) and some other simple exact solutions with nonzero energy-momentum-stress tensors; see also this about the form of the contribution of an EM field to the energy-momentum-stress tensor (e.g. in Reissner-Nordstrom or Kerr-Newman electrovacuum solutions),
• here about gravitational waves from black hole mergers,
• here about the optical appearance of a black hole to a nearby external observer,
• here and here about black hole mergers generally,
• here about dropping a small object into a black hole,
• here about "singularities" in gtr,
• here and here about gtr generally,
• here about black holes versus "point masses",
• in my Post #2 above, comparing various features which have been called "wormholes" in the gtr literature (with greater or lesser accuracy and greater or lesser degrees of physical plausibility)

My point is that gtr is a subtle subject and as the posts to which I was responding in the posts I cited above show (IMO), failure to think and write very carefully inevitably leads to confusion and misconceptions.

I think you are talking about the throat of something like the "eternal Schwarzschild vacuum" solution, which pinches off before any particle can get through. The whole point of the (dubious) speculation about hypothetical "stable wormholes" is that these would be filled with mysterious "stuff" which would in principle hold the wormhole open indefinitely. One problem with such speculation is that the "stuff" required probably doesn't exist. The basic problem with the putatively stable throat(s) of something like the Reissner-Nordstrom electrovacuum is that it is unstable against small perturbations due to infalling matter or radiation. As I already mentioned.

As I already explained, such statements are theory dependent. The classical black hole concept is well established in the context of gtr, which in turn is one of the most highly tested theories devised so far. The notion of Hawking radiation is so far only a theoretical concept, one which goes outside gtr and which has not yet been tested experimentally, but nonetheless is generally believed to be true on theoretical grounds, even though the theoretical arguments for it involve approximations rather than any exact and well-tested theory (such as gtr). The notion of black hole evaporation is another theoretical concept which also goes outside gtr, is even less well established than the existence of Hawking radiation, and again has not been tested.

Solidity is in the eye of the beholder, obviously. I feel it is terribly misleading not to provide the context which I described above.

I really doubt the OP was asking about scattering by black holes