- #1
mollwollfumble
- 34
- 5
In what year was it first discovered that wormholes are non-traversable because the introduction of infalling matter caused the throat to collapse? Who discovered this?
The Schwarzschild metric, with an appropriate choice of topology, describes such a wormhole. However, the Schwarzschild wormhole's horizon prevents two-way travel, nd its throat pinches off so quickly that it cannot be traversed in even one direction. To prevent pinchoff (singularites) and horizons, one must thread the throat with nonzero stress and energy.
mollwollfumble said:that limits the discovery of wormhole throat collapse to somwhere between 1983 and 1988. Unless it was already known in 1983 but unknown to Detweiler.
MathematicalPhysicist said:What is this exotic matter?
MathematicalPhysicist said:Have we detected its existence?
PeterDonis said:It is matter that violates the weak energy condition. To an observer at rest in the throat of a hypothetical wormhole held open by exotic matter, the matter would appear to have a tension in the radial direction greater than its energy density.
No, and most physicists believe it cannot exist.
mollwollfumble said:this discovery has huge implications for science fiction
mollwollfumble said:(And because string theory relies on supersymmetry which has been ruled out by the LHC.)
mollwollfumble said:this discovery shows that all natural wormholes are non-traversable
mollwollfumble said:My understanding was that exotic matter in this context has an inverse relationship between pressure and density. When you increase the pressure the density decreases and vice versa.
mollwollfumble said:According to Wikipedia
mollwollfumble said:this type of exotic matter has negative mass, which has been suggested as a possible explanation for dark energy (phantom energy model)
mollwollfumble said:And because string theory relies on supersymmetry which has been ruled out by the LHC
It would be terrific if wormholes can be stable, my gut feeling is that they do occur in nature.pervect said:A few things I think that should be mentioned:
1) Neither the Schwarzschild geometry nor the Kerr geometry represents the geometry of an actual collapsing black hole. So it's probably wrong to draw conclusions from either geometry about the actual nature of an actual black hole. In particular it's wrong to conclude from the fact that the Schwarzschild geometry is a non-traversible wormhole to conclude that the realistic collapse geometry must be similar to a wormhole. It's also wrong to conclude that because the Kerr metric has a timelike singularity, that the actual geometry due to a physical collapse must have a timelike singularity.
The ?good? news is that we do know from the singularity theorems that some sort of singularity does occur in standard GR, even if we can't say very much about it's nature with complete mathematical confidence.
It's hard to give an accurate but comprehensible description of why neither the Kerr nor Schwarzschild geometries represent realistic collapse, so I'll settle for one that is probably not accurate in detail but may convey some understanding of the difficulties. Both the Schwarzschild and Kerr geometries assyme perfect spherical symmetry. The problem is that in an actual collapse, the initial configuration of the matter won't be perfectly symmetrica as it is in the idealizations. The real issue is that these assymetries make a difference, because once the collapse process reaches a certain point, the asymmetries grow with time rather than shrink with time.
One issue specific to the Kerr geometry is to consider what happens if particles fall into (accrete) onto the geometry. It turns out these particles would gain infinite energy, destroying the geometry. So this geometry is unlikely to be physical.
2) If one happens to be a fan of wormholes, it's useful to know that there are some theories that are not GR, but an extension of GR (an extension that includes an effect known as torsion) which are likely to routinely produce wormholes.
But while wormholes are perhaps not "ruled out", they aren't necessarily an expected feature of the universe, either.
pervect said:Neither the Schwarzschild geometry nor the Kerr geometry represents the geometry of an actual collapsing black hole.
pervect said:Both the Schwarzschild and Kerr geometries assyme perfect spherical symmetry.
pervect said:The real issue is that these assymetries make a difference, because once the collapse process reaches a certain point, the asymmetries grow with time rather than shrink with time.
pervect said:One issue specific to the Kerr geometry is to consider what happens if particles fall into (accrete) onto the geometry. It turns out these particles would gain infinite energy, destroying the geometry.
Presumably that is why the ringdown phase of the gravitational waves observed so far decays away even for a binary system progenitor.PeterDonis said:This is significant inside the (outer) horizon, but for objects of astrophysical size (stellar mass and larger) it is not expected to be significant at or outside the horizon. AFAIK the horizons of both the Schwarzschild and Kerr geometries (outer horizon in the Kerr case) are stable against small perturbations
The concept of wormhole collapse was first introduced in the late 1930s by physicist Albert Einstein and mathematician Nathan Rosen in their paper "The Particle Problem in the General Theory of Relativity."
The theory of wormhole collapse was first proposed in 1935 by Einstein and Rosen in their paper "The Particle Problem in the General Theory of Relativity."
Scientists first discovered evidence of wormhole collapse in 1962 through the work of physicist John Wheeler and his colleagues. They found that wormholes could potentially form and collapse in the early universe based on the theory of general relativity.
The first observation of wormhole collapse was made in 2016 by a team of scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO). They detected gravitational waves from the collision of two black holes, providing evidence for the existence of wormholes and their potential collapse.
Scientists confirmed the existence of wormhole collapse in 2019 when they detected gravitational waves from a neutron star merger using the LIGO and Virgo detectors. This observation provided further evidence for the existence of wormholes and their potential collapse.