From: mk_thisisit
A singularity is a point of infinite density [00:14:26]. Within a black hole, it is expected that an object will be torn apart in the center, leading to a singularity [00:12:42].
The Oppenheimer-Snyder Model
The concept of gravitational collapse, as it relates to black holes, was explored in an article by J. Robert Oppenheimer, known for his work at Los Alamos and a famous movie, and his student Snyder [00:13:08], [00:13:14], [00:13:47].
Their article described a collapsing dust cloud [00:13:30]. This dust cloud collapses into what is now referred to as a black hole [00:13:37]. The term “black hole” was not used at the time of their publication [00:13:40], [00:13:43], [00:13:45], [00:14:34].
Key Assumptions of the Oppenheimer-Snyder Model
The model operates under two main assumptions:
- No Pressure: The collapsing dust cloud has no pressure, meaning nothing stops the collapse [00:13:56], [00:14:02], [00:14:04], [00:14:23].
- Perfect Spherical Symmetry: The collapse is exactly spherically symmetrical, like a ball, with everything falling towards the center [00:14:07], [00:14:09], [00:14:12], [00:14:15].
Under these conditions, the particles fall towards the center, creating a singularity of infinite density [00:14:18], [00:14:26].
Criticisms of the Oppenheimer-Snyder Model
Despite its elegance, many scientists did not fully believe in the Oppenheimer-Snyder article [00:13:50], [00:14:41]. The model was considered unrealistic for several reasons [00:14:43], [00:14:46]:
- Lack of Pressure: Real dust is not without pressure; small pieces collide, and forces can repel them [00:14:48], [00:14:50], [00:14:53], [00:14:55].
- No Spherical Symmetry: Realistic collapsing objects are not perfectly spherically symmetrical [00:14:57], [00:15:00]. Irregularities would make the collapse very complicated, potentially involving spinning or parts leaving the system [00:15:04], [00:15:06], [00:15:11], [00:15:13], [00:15:15]. The smaller the object becomes, the more significant these irregularities would be [00:15:29], [00:15:32].
It was widely believed that the Oppenheimer-Snyder model, while elegant, was unrealistic, particularly when approaching the singularity where densities become infinitely large and equations cannot be solved [00:15:19], [00:15:20], [00:15:22], [00:15:24], [00:15:37], [00:15:41], [00:15:43], [00:15:46], [00:15:48].
Theory of Irregular Collapse and the Inevitability of Singularities
A new approach considered irregular collapse, moving beyond the spherically symmetric limitations of the Oppenheimer-Snyder model [00:15:51], [00:15:53], [00:15:56], [00:15:59]. This involved defining a “trap surface” to describe a state collapsed in on itself after crossing a boundary, even if highly irregular [00:16:01], [00:16:04], [00:16:06], [00:16:09], [00:16:12].
Using advanced mathematics not typically used in this field, it can be demonstrated that the emergence of a singularity cannot be avoided [00:16:24], [00:16:26], [00:16:28], [00:16:31], [00:16:33]. This holds true unless the physical properties are changed, such as by introducing negative energy, which is not generally permitted [00:16:36], [00:16:38], [00:16:40], [00:16:42]. This conclusion, formalized into a theorem, indicates that singularities are unavoidable in such scenarios [00:18:32], [00:18:35], [00:18:37].
The development of this idea was influenced by a conversation with Ivor Robinson in London, during which the foundational insight occurred while crossing a street [00:17:07], [00:17:10], [00:17:13], [00:17:15], [00:17:31], [00:17:41], [00:17:43], [00:18:21]. This discovery brought a feeling of elation [00:17:55], [00:17:59].
Connection to Black Holes
The understanding of black holes involves the concept of absorption. For example, the Andromeda black hole is much larger than our galaxy’s black hole and is expected to “eat us for dinner,” though this will occur in billions of years [00:09:29], [00:09:31], [00:09:33], [00:09:35], [00:09:37].
Eventually, entire galaxy clusters will be absorbed by supermassive black holes [00:09:40], [00:09:47], [00:09:49], [00:09:51], [00:09:54], [00:09:58], [00:10:00]. Most stars will fall into these supermassive black holes [00:10:03], [00:10:05].
These black holes will persist for an incredibly long period, approximately 10^100 years [00:10:17], [00:10:20], [00:10:22]. After this time, they will gradually disappear through the phenomenon of Hawking evaporation [00:10:25], [00:10:28], [00:10:31]. This emitted energy then transitions to the next “aeon,” creating a visible point in the sky for a future observer [00:10:35], [00:10:38], [00:10:40]. This process is integral to the cyclic universe theory [00:08:59].
In a preceding aeon, black holes, galaxies, and galaxy clusters would have absorbed each other, eventually disappearing through Hawking evaporation over 10^100 years [00:10:47], [00:10:51], [00:10:54], [00:10:55], [00:10:59], [00:11:02], [00:11:05], [00:11:08]. The radiation from this process carries energy from the galactic cluster and, after breaking through the “last scattering surface,” forms a small point visible in our sky, known as cosmic microwave background radiation [00:11:10], [00:11:13], [00:11:15], [00:11:17], [00:11:24], [00:11:26], [00:11:29], [00:11:31], [00:11:33], [00:11:36].