Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: jeffreyH on 16/12/2015 23:06:33
-
An event horizon is thought to only expand over time via the accumulation of mass and therefore has an increase in mass density. Since the universe is expanding and so is decreasing in mass density does this mean that the idea that the universe itself is inside a black hole is a fallacy? Does this also mean that dark energy could be the force that drives a white hole?
-
Just for starters, most of the Matter/Energy budget of the Universe is already contained in the Universe's many Black Holes.
An event horizon is thought to only expand over time via the accumulation of mass and therefore has an increase in mass density.
I do not see where the increase of "Mass Density" comes from. Yes an Event Horizon is thought to expand with the accumulation of more Mass. That would suggest that the Black Hole already exists at maximum density.
If the Event Horizon did not increase with more Mass accumulation, then the density would have to increase.
Since the universe is expanding and so is decreasing in mass density does this mean that the idea that the universe itself is inside a black hole is a fallacy?
From a Human perspective of the Universe, the answer to this question would have to be yes, it is a fallacy.
However the Human observational perspective is not the only one. If we were to consider a reference frame near the Event Horizon of a Black Hole, relativity tells us that Time and Space take on a totally different perspective. Now everything we see when looking out at the Universe is heavily "Blue-shifted". Not only that but Space is heavily contracted.
The Universe would appear relatively small and contracting. From that time dilated reference frame the Big Bang didn't happen that long ago, didn't expand very far, and is rapidly contracting. Stars would light up and extinguish in an instant. They would look more like sparks.
I could go on and on but I think you get what I'm saying by now. It's all relative.
There may be some reference frame that makes sense of the idea that the universe itself is inside a black hole. (Shoulder shrug)
Does this also mean that dark energy could be the force that drives a white hole?
White Hole?
Although hypothesised, so are Unicorns, Hidden Dimensions, Fairies, Singularities, Gods, Gravitons, etc etc etc...
Hope that helps.
-
http://arxiv.org/ftp/astro-ph/papers/0608/0608389.pdf
Chapline has a look at some related ideas.
-
most of the Matter/Energy budget of the Universe is already contained in the Universe's many Black Holes
It is thought that the black hole in the center of most galaxies has a mass of about 0.1% of the central bulge (http://en.wikipedia.org/wiki/M%E2%80%93sigma_relation#Importance).
One of the early candidates for Dark Matter in the galaxy was stellar-mass black holes (http://en.wikipedia.org/wiki/Dark_matter#History_of_the_search_for_its_composition) (the ashes of a supernova). But searches for gravitational lensing suggested that stellar mass black holes are not common enough to account for Dark Matter.
So I suggest that Black Holes make up a small (but growing) percentage of the mass of the universe.
does this mean that the idea that the universe itself is inside a black hole is a fallacy?
One of the theoretical principles of Black Holes is that nothing can escape, apart from the slow emission of Hawking radiation.
One of the theoretical principles of Cosmic Inflation (http://en.wikipedia.org/wiki/Inflation_(cosmology)) is that the universe at one time was smaller than a grapefruit.
The mass of the universe in the size of a grapefruit is certainly enough to form a black hole.
- And having formed a black hole, nothing can escape
- The effects of Hawking Radiation can be effectively ignored for a black hole more massive than the Sun.
So I suggest that it is possible for the entire universe to be within a black hole, as unpalatable as that may be for those who want unlimited horizons. What happens inside the event horizon of a black hole is almost unknowable to those outside it.
-
So I suggest that it is possible for the entire universe to be within a black hole, as unpalatable as that may be for those who want unlimited horizons. What happens inside the event horizon of a black hole is almost unknowable to those outside it.
This observation is thought provoking because there are many theorists who suggest that there is no outside when speaking about our universe. This raises the question; If our universe is a black hole, why would there be no outside to it when we certainly observe and recognize black holes at the center of most galaxies? Because these black holes most assuredly have things outside, why wouldn't our universe have an outside as well? As for myself, I reckon that our universe must also have an outside.
This point of view suggests that while our universe is finite, it may lie within an infinite expanse where an infinite number of black hole universes exist. And the black holes we observe within our local universe may be separate and distinct universes as well. All too grand for the human mind to grasp!
-
You have to consider how a geodesic would be described within an event horizon. It would be the shortest path to the singularity. This is complicated by rotation and the existence of an ergosphere. Nevertheless it can only be a straight line to the singularity in cases of extreme density when the initial mass before collapse was small. For much larger objects, such as the universe, the gravitational force at the surface of the horizon would be extremely small and yet the escape velocity must still equal c. There is something wrong with this picture. If we can easily orbit VERY close to the horizon since the pull is infinitesimally small then how can it trap anything by just moving a little closer? The pull will still be infinitesimally small just inside the horizon. There is nothing to stop us from escaping. Unless the horizon is moving away from the centre. This indicates that above a certain size of mass we can only have white holes with an expanding Rindler horizon. This describes an expanding universe.