Black Holes and/or Wormholes:

[beecee]

https://phys.org/news/2018-06-speculative-wormhole-echoes-revolutionize-astrophysics.html

Speculative wormhole echoes could revolutionize astrophysics

June 12, 2018, Plataforma SINC

The scientific collaborations LIGO and Virgo have detected gravitational waves from the fusion of two black holes, inaugurating a new era in the study of the cosmos. But what if those ripples of space-time were not produced by black holes, but by other exotic objects? A team of European physicists suggest an alternative—wormholes that can be traversed to appear in another universe.
 

Scientists have deduced the existence of black holes from a multitude of experiments, theoretical models and indirect observations such as the recent LIGO detections, which are believed to originate from the collision of two of these dark gravitational monsters.

But there is a problem with black holes—they present an edge, called an event horizon, from which nothing can escape. This is in conflict with quantum mechanics, whose postulates ensure that information is always preserved, not lost.

One of the theoretical ways to deal with this conflict is to explore the possibility that the alleged black holes we 'observe' in nature are no such thing, but rather some type of exotic compact objects (ECOs), such as wormholes, which do not have an event horizon.

Read more at: https://phys.org/news/2018-06-speculative-wormhole-echoes-revolutionize-astrophysics.html#jCp

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the paper:

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.97.024040

Echoes of Kerr-like wormholes:

 

ABSTRACT:

Structure at the horizon scale of black holes would give rise to echoes of the gravitational wave signal associated with the post merger ringdown phase in binary coalescences. We study the waveform of echoes in static and stationary, traversable wormholes in which perturbations are governed by a symmetric effective potential. We argue that echoes are dominated by the wormhole quasinormal frequency nearest to the fundamental black hole frequency that controls the primary signal. We put forward an accurate method to construct the echoes’ waveform(s) from the primary signal and the quasinormal frequencies of the wormhole, which we characterize. We illustrate this in the static Damour-Solodukhin wormhole and in a new, rotating generalization that approximates a Kerr black hole outside the throat. Rotation gives rise to a potential with an intermediate plateau region that breaks the degeneracy of the quasinormal frequencies. Rotation also leads to late-time instabilities that, however, fade away for small angular momentum.

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Wormholes, Einstein Rosen Bridges? These are speculated to exist at the singularity region of a BH. So can we also logically speculate that what we are seeing are "naked singularities"? 

Wormholes of course are allowed for by GR.

an extract from the article....."The confirmation of echoes in the LIGO or Virgo signals would be a practically irrefutable proof that astrophysical black holes don't exist," Bueno says, adding, "Time will tell if these echoes exist or not. If the result were positive, it would be one of the greatest discoveries in the history of physics."

I have a problem with the above....Any future confirmation of echoes would validate wormholes and/or ERB's, but why would they invalidate BH's? Why couldn't both exist? [It certainly would show that the five affirmed discoveries of binary BH accretion events were not BH's, but why does that supposedly invalidate BH's in general? ]

[T. McGrath]

Isn't a wormhole a black hole at either end, with a conjoined singularity?  How could a wormhole not have an event horizon?  If black holes don't exist, what was that accretion disc orbiting in Cygnus X-1?  I'm willing to discuss the possibility that we may not know precisely what happens after the matter collapses beyond its Schwarzschild radius, but the fact that matter does indeed collapse at least to that point is irrefutable.  We have witnessed too many core collapse supernovae and measured stars orbiting extremely massive, yet invisible, objects to simply dismiss black holes out of hand.

[beecee]

51 minutes ago, T. McGrath said:

Isn't a wormhole a black hole at either end, with a conjoined singularity?  How could a wormhole not have an event horizon? 

Wormholes, Einstein Rosen Bridges? These are speculated to exist at the singularity region of a BH. So can we also logically speculate that what we are seeing are "naked singularities"? 

But wouldn't one throat of a wormhole act like a BH, and the other like a White Hole?

 

Bingo!! I said it somewhere else today [perhaps in my tutorial summary of BH's? too lazy to look ]if BH's don't exist, then we would have an even more counter intuitive, incredible object to describe and catorgorise.  The effects we do see, including as you said, accretion disks, and the fact that we have observed them [Cygnus X-1] actually disappearing into nothing [BH]    along with recent GW discoveries have shown BH's to be as near certain as we could wish.