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3834 - BLACKHOLES
- Do SINGULARITIES
exist? The singularity at the
center of a black hole is the ultimate no man's land: a place where matter is
compressed down to an infinitely tiny point, and all conceptions of time and
space completely break down. And if it doesn't really exist something has to
replace the singularity.
--------- 3834 - BLACKHOLES - Do SINGULARITIES exist?
- “Planck stars”. It could be that deep inside a black hole,
matter doesn't get squished down to an infinitely tiny point. Instead, there
could be a smallest possible configuration of matter, the tiniest possible
pocket of volume.
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- This is called a “Planck star”, and it's a
theoretical possibility envisioned by “loop quantum gravity”, which is itself a
highly hypothetical proposal for creating a quantum version of gravity. In the
world of loop quantum gravity, space and time are quantized, the universe
around us is composed of tiny discrete chunks, but at such an incredibly tiny
scale that our movements appear smooth and continuous.
-
- This theoretical chunkiness, 3
dimensions, of space-time provides two
benefits. One, it takes the dream of quantum mechanics to its ultimate
conclusion, explaining gravity in a natural way. And two, it makes it
impossible for singularities to form inside black holes.
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- As matter squishes down under the immense
gravitational weight of a collapsing star, it meets resistance. The
discreteness of space-time prevents matter from reaching anything smaller than
the Planck length ( 1.68
* 10^-35 meters). All the material that
has ever fallen into the black hole gets compressed into a ball not much bigger
than this, definitely not infinitely tiny.
-
- This resistance to continued compression
eventually forces the material to un-collapse (i.e., explode), making black
holes only temporary objects. But because of the extreme time dilation effects
around black holes, from our perspective in the outside universe it takes billions,
even trillions, of years before they go boom.
-
- “Gravastars.” Another attempt to replace the singularity,
one that doesn't rely on untested theories of quantum gravity, is known as the
“gravastar.” The difference between a black hole and a gravastar is that
instead of a singularity, the gravastar is filled with dark energy.
-
- “Dark energy” is a substance that permeates
space-time, causing it to expand outward.
Dark energy is currently in operation causing our entire universe to accelerate
in its expansion.
-
- As matter falls onto a gravastar, it isn't
able to actually penetrate the event horizon (due to all that dark energy on
the inside) and therefore just hangs out on the surface. But outside that
surface, gravastars look and act like normal black holes.
-
- However, recent observations of merging
black holes with gravitational wave detectors have potentially ruled out the
existence of gravastars, because merging gravastars will give a different
signal than merging black holes, and LIGO (the Laser Interferometer
Gravitational-Wave Observatory) and Virgo are getting more and more examples by
the day.
-
- The idea of a single point of infinite
density comes from our conception of stationary, non-rotating, uncharged, black holes. The spin of a rotating black
hole stretches the singularity into a ring, not a dot.
-
- And, according to the math of Einstein's
theory of general relativity, once you pass through the ring singularity, you
enter a wormhole and pop out through a “white hole” (the polar opposite of a
black hole, where nothing can enter and matter rushes out at the speed of
light) into an entirely new patch of the universe.
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- The singularity, stretched into a ring,
rotating at such a fantastic pace has incredible centrifugal force. And in
general relativity, strong enough centrifugal forces act like antigravity: they
push, not pull.
-
- This creates a boundary inside the black
hole, called the “inner horizon”. Outside this region, radiation is falling
inward towards the singularity, compelled by the extreme gravitational pull.
But radiation is pushed by the antigravity near the ring singularity, and the
turning point is the inner horizon.
-
- If you were to encounter the inner horizon,
you would face a wall of infinitely energetic radiation, the entire past
history of the universe, blasted into your face in less than a blink of an eye.
-
- The formation of an inner horizon sows the
seeds for the destruction of the black hole. But rotating black holes certainly
exist in our universe, so that tells us that our math is wrong.
-
- What's really happening inside a black
hole? We don't know and the scary part is that we may never know.
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January 20, 2022 BLACKHOLES -
Do SINGULARITIES exist?
3834
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“Jim Detrick” -----------
--------------------- --- Saturday, January 21, 2023 ---------------------------
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