What is beyond the horizon of a black hole?

[Celerity]

Cosmic imposters

We know that black holes are strange, but they could be hiding something even weirder beyond their horizons

https://aeon.co/essays/black-holes-may-be-hiding-something-that-changes-everything


The polarised view of the black hole in the Messier 87 galaxy. The lines mark the orientation of polarisation, which is related to the magnetic field around the shadow of the black hole. Courtesy EHT Collaboration



What came first, the chicken or the egg? Perhaps a silly conundrum already solved by Darwinian biology. But nature has supplied us with a real version of this puzzle: black holes. Within these cosmic objects, the extreme warping of spacetime brings past and future together, making it hard to tell what came first. Black holes also blur the distinction between matter and energy, fusing them into a single entity. In this sense, they also warp our everyday intuitions about space, time and causality, making them both chicken and egg at once.

Physicists like me have long since accepted these strange properties of black holes. But I suspect that nature could very well have played a different trick altogether, and made black holes a gateway to something far more unusual – a region where the rules of spacetime themselves transform into something we’ve never seen before. Many objects we think of as black holes may, in fact, be imposters: identical on the outside but harbouring entirely different physics within. Finding out whether that’s true will require peeling back the shell of reality itself. And humankind is getting closer to doing exactly that.

To understand why black holes may be hiding something, let’s first recap how gravity works, because it is the foundation of how spacetime can curve itself into such exciting and mysterious objects. Before Albert Einstein’s theories, gravity had various unexplained features. Isaac Newton’s gravity states that the planets feel the Sun through the vacuum of space with no interaction whatsoever. What’s more, it also states that any interaction takes zero time. If we were to remove the Sun with the flick of a wand, Newton’s gravity suggests the planets would immediately be stripped from the Sun’s gravitational pull, contradicting the well-known fact that nothing travels faster than light.



It was Einstein who found the solution to this puzzle. All he needed was the simplest of observations: all objects drop in exactly the same way under the pull of gravity. Lift up a bowling ball in one hand and a cauliflower in the other, and you notice that one arm is struggling more. Yet, when dropped, both bowling ball and cauliflower fall equally fast and hit the floor at the same moment. Whatever difference there was in mass, gravity nullifies it on the way down. This reveals something very deep about nature. Just like the train tracks’ curves make every train follow the same twists and turns, the fact that the gravitational motion of all objects is the same reveals that this too must be due to curves, this time in space itself.

snip


A European Space Agency artist’s interpretation of spacetime depicted as a simplified, two-dimensional surface, which is being distorted by the presence of three massive bodies, represented as coloured spheres. The distortion caused by each sphere is proportional to its mass. Courtesy ESA/C Carreau

[LymphocyteLover]

1. this excerpt is very meandering and frankly not very convincing

[Intractable]

2. Unrec