APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
From Sagittarius to Scorpius, the central Milky Way is a truly beautiful part of planet Earth's night sky. The gorgeous region is captured here, an expansive gigapixel mosaic of 52 fields spanning 34 by 20 degrees in 1200 individual images and 200 hours of exposure time. Part of ESO's Gigagalaxy Zoom Project, the images were collected over 29 nights with a small telescope under the exceptionally clear, dark skies of the ESO Paranal Observatory in Chile. The breathtaking cosmic vista shows off intricate dust lanes, bright nebulae, and star clusters scattered through our galaxy's rich central starfields. Starting on the left, look for the Lagoon and Trifid nebulae, the Cat's Paw, the Pipe dark nebula, and the colorful clouds of Rho Ophiuchi and Antares (right).
Nobody proposes that there is a swarm of black holes in the center of the Milky Way. So I don't think you can fault the video for not discussing such a thing.harry wrote:The image and the video are great, but! the explanation falls short in explaining the probable activity of the swarm of so called black holes that I would rather refer to as ultra compact matter that mimic the trapping horizons and still allow the formation of jets that we can observe in these areas as indicated in one of the APODS.
Rather than treating these compact objects as black holes, the point being to treat them as compact bodies and apply known properties to their "THING" this way we do not have the classical BH with Zero volumn and Event horizons that is based on ad hoc theories without observational evidence.Explanation: What do you call a group of black holes ... a flock, a brace, a swarm? Monitoring a region around the center of our Galaxy, astronomers have indeed found evidence for a surprisingly large number of variable x-ray sources - likely black holes or neutron stars in binary star systems - swarming around the Milky Way's own central supermassive black hole. Chandra Observatory combined x-ray image data from their monitoring program is shown above, with four variable sources circled and labeled A-D. While four sources may not make a swarm, these all lie within only three light-years of the central supermassive black hole known as Sgr A* (the bright source just above C). Their detection implies that a much larger concentration of black hole systems is present. Repeated gravitational interactions with other stars are thought to cause the black hole systems to spiral inward toward the Galactic Center region.
I don't think so. There is a swarm of ordinary stars orbiting Sag A*. That a few of these happen to be black holes doesn't seem too extraordinary.harry wrote:Chris I think you missed the point.
Well, then, I think you missed the point. They are black holes, so that is how they are "treated".Rather than treating these compact objects as black holes, the point being to treat them as compact bodies and apply known properties to their "THING" this way we do not have the classical BH with Zero volumn and Event horizons that is based on ad hoc theories without observational evidence.
Black holes all have a finite volume. Maybe you are confusing the singularity at the center of a black hole (which may not even exist) with the entire black hole? And all black holes have event horizons. I'm not clear what your point is.harry wrote:Than define a Black hole that does not have a zero volumn and an event horizon.
Chris Peterson wrote:Black holes all have a finite volume.
Because thats not how the time line works. Time cannot be changed.If a singularity can create, "Space Time" Why cannot a Singularity destroy "Space Time"? And that a Black Hole is a one way trip, back to before the big bang and Time.
Parampreet Singh has written some interesting papers on the topic.Abstract: A unified treatment of all known types of singularities for flat, isotropic and homogeneous spacetimes in the framework of loop quantum cosmology (LQC) is presented. These include bangs, crunches and all future singularities. Using effective spacetime description we perform a model independent general analysis of the properties of curvature, behavior of geodesics and strength of singularities. For illustration purposes a phenomenological model based analysis is also performed. We show that all values of the scale factor at which a strong singularity may occur are excluded from the effective loop quantum spacetime. Further, if the evolution leads to either a vanishing or divergent scale factor then the loop quantum universe is asymptotically deSitter in that regime. We also show that there exist a class of sudden extremal events, which includes a recently discussed possibility, for which the curvature or its derivatives will always diverge. Such events however turn out to be harmless weak curvature singularities beyond which geodesics can be extended. Our results point towards a generic resolution of physical singularities in LQC.
I have a better question: if a black hole can create a spaghetti out of spaceships, why can't it create spaceships out of spaghetti? Instead, all we have are those silly jets.mark swain wrote:If a singularity can create, "Space Time" Why cannot a Singularity destroy "Space Time"?
I don't know what you mean by "contextual". Black holes are well described by current theory, and most all theorists are describing about the same thing. Questions about them are mainly concerned with their interiors, where our current physics appears to break down. Read about them on Wikipedia if you want to understand the most common viewpoint.harry wrote:Black hole today are very contextual. Plsease define what you think they are.
Many would agree with you about a classical singularity. But that doesn't necessarily reflect on the existence of black holes, because there is no certainty at all that a black hole contains a singularity. In fact, it is the production of a singularity by theoretical models that provides some of the best evidence that our physics is currently inadequate to describe a black hole's interior. I, for one, think it is unlikely that physical singularities exist, but I certainly have little doubt that black holes are real- that is, dense objects with true event horizons, describable as simple particles with just a few properties, and into which energy disappears, not to be released again for many trillions of years.I for one do not think they exist, for the simple reason that a classical singularity cannot form.
The bit about not to be released for many trillions of years. Logic holds that if the BBT is correct than trillions of years would not be logical.Many would agree with you about a classical singularity. But that doesn't necessarily reflect on the existence of black holes, because there is no certainty at all that a black hole contains a singularity. In fact, it is the production of a singularity by theoretical models that provides some of the best evidence that our physics is currently inadequate to describe a black hole's interior. I, for one, think it is unlikely that physical singularities exist, but I certainly have little doubt that black holes are real- that is, dense objects with true event horizons, describable as simple particles with just a few properties, and into which energy disappears, not to be released again for many trillions of years.
Why not? Black holes evaporate, and the evaporation rate depends on their size. In order for stellar mass black holes to radiate faster than they absorb from the microwave background, they need to be warmer than that background. That isn't currently the case. It is only after the Universe gets much, much older that the background temperature will be low enough that black holes will start losing mass. It is the BBT theory that leads to the conclusion that the Universe is cooling, and therefore that there will come a time when black holes can finally evaporate.harry wrote:The bit about not to be released for many trillions of years. Logic holds that if the BBT is correct than trillions of years would not be logical.
Certainly, if one is studying neutron stars, which are made up of matter that can still be understood in terms of phase states. That doesn't describe black holes, however.harry wrote:One needs to understand the phase changes that matter undergoes in Star bodies and the mechanism by which such matter changes with various fields including Gravity, EM and subatomic.
I am another scientist who would like to take part. However, I don't think I can sum things up better than Chris Peterson has. Once again, good job explaining difficult technical points, Chris.harry wrote: we need to invite other scientists to take part.
harry wrote:Hello Mark
You said
If a singularity can create, "Space Time" Why cannot a Singularity destroy "Space Time"? And that a Black Hole is a one way trip, back to before the big bang and Time.
Because thats not how the time line works. Time cannot be changed.
but! the point of a rebounce is probable.
makc wrote:I have a better question: if a black hole can create a spaghetti out of spaceships, why can't it create spaceships out of spaghetti? Instead, all we have are those silly jets.mark swain wrote:If a singularity can create, "Space Time" Why cannot a Singularity destroy "Space Time"?