Origin of our universe 4D black hole

[StonedPhysicist]

The brains at the Perimeter Institute recently published a paper describing how our 3 dimensional universe could possibly exist as the event horizon of a 4 dimensional black hole in a 4 dimensional universe as the event horizons of black holes have one less dimension than the black hole itself and the universe it occupies.

I was wondering what others think of this model and if this also suggests that our 3 dimensional black holes have themselves got a 2 dimensional universe within their event horizons.

Here is a link to an article on the paper: http://phys.org/news/2014-08-black-hole-birth-universe.html

 

[jedishrfu]

Pretty interesting notion.

 

[phinds]

Sounds like mathematical nonsense to me, but that's just the engineer in me talking, not anything based on scientific knowledge.

 

[Drakkith]

I'm much more inclined to believe that GR is not accurate at black hole scales and there isn't really a singularity at all.

 

[Doug Huffman]

Out of the White Hole: A Holographic Origin for the Big Bang http://arxiv.org/abs/1309.1487 is the only paper at ArXiv in the senior author's list and with the same junior authors as in the Phys.org.asm article. Citation by Scientific American does their credibility no good.

 

[StonedPhysicist]

Sounds like mathematical nonsense to me, but that's just the engineer in me talking, not anything based on scientific knowledge.

I believe they say there is a way to prove it (or disprove it)!

 

[phinds]

I'm much more inclined to believe that GR is not accurate at black hole scales and there isn't really a singularity at all.

Actually, that's a pretty widespread belief these days, isn't it? I certainly share it and if I do then dammit, everybody should !

 

[phinds]

I believe they say there is a way to prove it (or disprove it)!

Nothing is ever proved in physics, only in math. Things can easily be DISproved in physics.

If someone develops some solid evidence in favor, I'll reconsider my disbelief.

 

[StonedPhysicist]

Nothing is ever proved in physics, only in math. Things can easily be DISproved in physics.

If someone develops some solid evidence in favor, I'll reconsider my disbelief.

Things can be proved? like proving light has wave like properties with the double slit experiment...

 

[Drakkith]

Things can be proved? like proving light has wave like properties with the double slit experiment...

I'm not quite sure what you're getting at here.

 

[phinds]

Things can be proved? like proving light has wave like properties with the double slit experiment...

This is NOT a proof. It is an empirical observation.

 

[D H]

Things can be proved? like proving light has wave like properties with the double slit experiment...

To a logician, that proves nothing.

Think of it this way. Newton published his Philosophiæ Naturalis Principia Mathematica in 1687. Scientists tested this theory, engineers used this theory, and for the next 300 years and never found a cool person. There obviously were some chinks. My computer, your GPS unit, and a host of other technical wonders of the 20th an 21st century wouldn't exist if Newtonian mechanics was universally true.

One challenge confronted by quantum theory and relativity theory was to somehow explain how even though Newtonian mechanics is fundamentally flawed, it still appears to work very, very well in a limited domain. Physicists of the future will be confronted with the same problem when something better than quantum theory and relativity theory comes along. They'll have to explain that even though our quantum and relativity theories are fundamentally flawed, they still do appear to work extremely well in their limited domains.

 

[StonedPhysicist]

not sure I agree, if I see an apple fall off a tree, there MUST be a force acting on the apple, therefore i can say that my observation proves there is a force acting on the apple

 

[Drakkith]

not sure I agree, if I see an apple fall off a tree, there MUST be a force acting on the apple, therefore i can say that my observation proves there is a force acting on the apple

A "force" is a concept invented to explain why objects are accelerated. There is no proof that forces exist. It is simply the best explanation we have and allows us to predict how an object will act in a given situation.

 

[StonedPhysicist]

The proof is the fact the apple falls? It would only fall if the concept of a 'force' was real, thus it is real

 

[Drakkith]

The proof is the fact the apple falls? It would only fall if the concept of a 'force' was real, thus it is real

I would say that you observe that the apple falls. In an attempt to explain why and how, you can use the concept of a "force" acting on the apple to predict how fast it falls, when it will hit the ground, at what velocity, etc. There is no "proof" anywhere here.

 

[StonedPhysicist]

lets agree to disagree, this is well off the topic of this thread.

 

[Torbjorn_L]

The brains at the Perimeter Institute recently published a paper describing how our 3 dimensional universe could possibly exist as the event horizon of a 4 dimensional black hole in a 4 dimensional universe as the event horizons of black holes have one less dimension than the black hole itself and the universe it occupies.

While I have never studied general relatiovity, I'm wary of black holes as models of a universe since they differ in details:

"Note that the maximally extended Schwarzschild metric describes an idealized black hole/white hole that exists eternally from the perspective of external observers; a more realistic black hole that forms at some particular time from a collapsing star would require a different metric. When the infalling stellar matter is added to a diagram of a black hole's history, it removes the part of the diagram corresponding to the white hole interior region.[6] But because the equations of general relativity are time-reversible (they exhibit T-symmetry), general relativity must also allow the time-reverse of this type of "realistic" black hole that forms from collapsing matter. The time-reversed case would be a white hole that has existed since the beginning of the universe, and which emits matter until it finally "explodes" and disappears.[7] Despite the fact that such objects are permitted theoretically, they are not taken as seriously as black holes by physicists, since there would be no processes that would naturally lead to their formation, they could only exist if they were built into the initial conditions of the Big Bang.[7] Additionally, it is predicted that such a white hole would be highly "unstable" in the sense that if any small amount of matter fell towards the horizon from the outside, this would prevent the white hole's explosion as seen by distant observers, with the matter emitted from the singularity never able to escape the white hole's gravitational radius.[8]"

[ http://en.wikipedia.org/wiki/White_hole ; my bold]

The larger claim of our universe being a variant of a black hole seems generically be an extraordinary claim without any (extra)ordinary evidence. The smaller claim that BHs contain universes can safely be rejected I think.

 

[StonedPhysicist]

hmm I wish I could look at the maths for all this and get to grips with it, i think i would understand it a lot better if i did so. There is only so much you can understand from reading words, a lot more can be understood from the maths.

 

[Torbjorn_L]

Off topic:

It would only fall if the concept of a 'force' was real, thus it is real

I think this confuses the notion of reality (robust observations) with the notion of theories (robust predictors).

 

[StonedPhysicist]

Off topic:I think this confuses the notion of reality (robust observations) with the notion of theories (robust predictors).

By theory you mean the mathematical models yes? Why can't these be reality?

 

[jedishrfu]

For the physical world, we can only have models that tell us how things work. These models are mathematical they have no basis in reality other than providing us with a means to predict things and conceptually understand things.

This was something I struggled with when I was a student. I look at it now when I compare a computer simulation with reality. The sim predicts many things and I can test it against reality but that doesn't mean reality works like my program.

 

[StonedPhysicist]

so what if we found a theory of everything that described all fundamental quantities with 100% accuracy? would this not be a reality?

 

[madness]

I think this confuses the notion of reality (robust observations) with the notion of theories (robust predictors).

I don't think "robust observations" are reality because of this http://en.wikipedia.org/wiki/Noumenon, unless you are an idealist who doesn't believe in an external world outside of your senses.

On the other hand theories are (in my opinion) definitely further from reality than observations. The use of force as an example ("It would only fall if the concept of a 'force' was real, thus it is real") is a bit ironic, since gravity has since been classified as an effect of geometry rather than a force.

 

[jedishrfu]

so what if we found a theory of everything that described all fundamental quantities with 100% accuracy? would this not be a reality?

No. The theory would describe everything but its still a mathematical model of how things work with no basis in reality. We can never know if someday some new phenomena is discovered athat our theory doesn't explain.

 

[jedishrfu]

I suggest we close this thread as we are getting off topic.

 

[madness]

No. The theory would describe everything but its still a mathematical model of how things work with no basis in reality. We can never know if someday some new phenomena is discovered athat our theory doesn't explain.

Even if, hypothetically, we did discover some exact set of mathematical laws which describe exactly how every detail in our universe behaves, it would still not be "reality", it would just be a description of it.

 

[jedishrfu]

Even if, hypothetically, we did discover some exact set of mathematical laws which describe exactly how every detail in our universe behaves, it would still not be "reality", it would just be a description of it.

So we are in agreement, right?

 

[madness]

So we are in agreement, right?

I think so :)

 

[StonedPhysicist]

But perhaps our own universe is a computer simulation, which there is no way to prove or disprove at the moment, so if it is a computer simulation, in this case there would have to be an underlying mathematical model that IS reality because our universe is governed by it?

 

[jedishrfu]

But perhaps our own universe is a computer simulation, which there is no way to prove or disprove at the moment, so if it is a computer simulation, in this case there would have to be an underlying mathematical model that IS reality because our universe is governed by it?

Give it a rest. You're just trying to win an argument that you have already lost.

Moderators, please close this thread.

 

[Doug Huffman]

I recommend Karl Popper's The Logic of Scientific Discovery for his insights into verification-ism as proof and developed a much better solution to the Problem of Demarcation in falsifiability. On point, fifty years after 'Logic' he wrote an anniversary postscript that grew into three volumes, one of which is Quantum Theory and the Schism in Physics: From the Postscript to the Logic of Scientific Discovery (1992 Routledge).

On proof, in general, a number of contemporaries, influential at least to me, caution against naive use of inductive inference for not reliably revealing the Black Swan hiding, camouflaged in the background complexity of reality. An assertion of non-existence cannot be sustained without examination of the entire universe of discussion. In physics and cosmology that is clearly impossible.

 

[Doug Huffman]

Our young member must needs read on the Boltzmann Brain and the Boltzmann Babies paradox, aspects of cosmological natural selection, and beware of infinite regressions.

Later; and of ad-hockery! Make your argument and let it stand or fall on its original structure, rather than patching and shoring a shaky structure into a cracker-box.

 

[Orodruin]

The discussion in this thread is no longer on the original topic. The thread will therefore remain closed.