The Nature of the Universe, Time Travel and More...

[Toril Toran]

Could this river of stars be the Bifrost Bridge between Midgard and Asgard? Now that would make an interesting story.

 

[Will The Serious]

Some have theorized the proposed Planet 9 is a small black hole.

I hope so…that might be used.

I just saw an article about some proposed use for miniature blackholes created in a lab. I didn't read the article, but the idea has some intriguing possibilities.

Professor Kazzak, the Vulcan Gravitics scientists in my own fan-fic series, is working on a method of inducting energy from the gravity lines of curved space as their ship travels crosses them. Other than harnessing the power of falling water or some similar relationship to gravity, how would gravity even hold energy if it is only a geometry to space-time? Stand on a road, then curve, bend or twist that road all you want, you will never get closer to a distant point, nor gain energy from the shape of the road. The best you can hope to achieve would be to make that road as straight as possible between yourself and that distant point, so you don't expend more energy to traverse the distance.

Perhaps, by converting distance and time to energy units, you can begin to approach the practical nature of the problem of curved space and express it in useful terms.

-Will

 

[Toril Toran]

I think gravity could give you a small amount of potential energy ( on say, a curved road) but it would most likely detract energy.

<Quote>Perhaps, by converting distance and time to energy units, you can begin to approach the practical nature of the problem of curved space and express it in useful terms.</Quote>

Some sort of 3D topographic map to figure out the effects of curvature on space/time?

 

[Will The Serious]

Some sort of 3D topographic map to figure out the effects of curvature on space/time?

In terms of topographical illustrations, this type of analogy is strictly a 2D representation of a 3+dimensional phenomenon. It basically uses gravity to explain itself.

-Will

 

[Asbo Zaprudder]

Indeed, such illustrations can be misleading. The path representing the orbit of one mass about another mass is called a time-like geodesic. To understand General Relativity, you need to understand special relativity, linear algebra, calculus, vectors, tensors, differential geometry, and Riemannian geometry. The following book by Leonard Susskind might be an aid to understanding:

General Relativity: The Theoretical Minimum: Amazon.co.uk: Susskind, Leonard, Cabannes, Andre: 9780141999869: Books

Here's a screenshot of the contents:

The Kindle edition is $20 in the US. It's the fifth book in a series based on lecture notes. The other four books cover prerequisite knowledge (the "theoretical minimum"), classical mechanics, quantum mechanics, and special relativity and classical field theory. It's not possible to understand these subjects without understanding the mathematics. If you can't get to grips with the mathematics, please find something else to occupy you to avoid wasting your own time. The English language is just not up to the task of describing all the nuances, which is why pop science explanations often fall short. Sometimes, the implications of mathematical descriptions aren't even readily apparent to the physicists who derived them.

 

[Asbo Zaprudder]

I realise I might be coming over as elitist, but my experience shows me that serious discussions about advanced physics require mathematics. It wasn't until people such as Newton, Lagrange and Riemann invented the mathematical tools that the subject could advance. Using ordinary language on its own just isn't able to provide the predictive power and falsifiable results that are required.

 

[Will The Serious]

https://bigthink.com/starts-with-a-bang/singularities-dont-exist-roy-kerr/

• Way back in 1963, Roy Kerr became the first person to write down the exact solution, in general relativity, for a realistic, rotating black hole. 60 years later, it's still used everywhere.
• Although Roger Penrose won the Nobel Prize in physics just a few years ago for demonstrating how black holes come to exist in our Universe, singularities and all, the subject isn't closed.
• We've never peered beneath the event horizon, and have no way of detecting what's inside. Using a powerful mathematical argument, Kerr argues that singularities shouldn't physically exist. He may be right.

Having been born "way back" in 1963, I'm not sure how I should feel about the way that date was referenced.

And, because this is just a really cool picture from the article, that could have come right out of 1963:

Now this article clarifies a concept I had not realized I was mistaken about. I thought a singularity and a black hole were one and the same.

-Will

 

[Asbo Zaprudder]

A singularity is a mathematical term - basically, you can think about it as a place where the mathematics implies you have to divide by zero - it's really telling you that your theories are not up to the job.

My suspicion is that the vacuum changes phase and new laws apply -- perhaps well before one reaches a Planck distance (10^-35 m) from the origin. Even if you could reduce the tidal effects by entering a very massive black hole, nothing can record what happens inside the event horizon as no communication can occur outward radially. In a way, space becomes time-like as the only allowed path is inward. Tidal forces eventually rip the object apart and the centre (whatever it is) is reached in finite time if the object were able to measure it. However, an external observer never sees the object cross the event horizon. They see it become frozen just above the event horizon as it becomes red-shifted and dimmer and dimmer until it effectively disappears.

We don't have a unified theory of gravity and quantum mechanics that would allow us to describe conditions at the centre. Loop quantum gravity suggests the energy of an object might get squirted out somewhere else as a white hole, but it's not clear if unitarity is obeyed and information about the original object is retained. The same applies for Hawking radiation. Penrose still believes that unitarity is not obeyed, although his former PhD student Hawking changed his own mind on this late in his life.

 

[Toril Toran]

Sounds like the particles of the object that entered could get pushed out a white hole, just not intact (protons, neutrons, electrons, or perhaps as subatomic particles)

 

[Asbo Zaprudder]

Sounds like the particles of the object that entered could get pushed out a white hole, just not intact (protons, neutrons, electrons, or perhaps as subatomic particles)

Yes, we just don't know. If we knew for certain that unitarity is conserved, we might have more of a clue. If the white hole is actually a big bang, perhaps the energy ends up creating a new universe imprinted with information from the one containing the black hole; perhaps the information is lost and the new universe has a completely different particle zoo, fundamental constants and set of physical laws. I don't know if branchial space theory offers any insights as we don't know if or how the properties of the ruliad can vary between instantiations of universes.

Ruliad -- from Wolfram MathWorld.

 

[publiusr]

And, because this is just a really cool picture from the article, that could have come right out of 1963:

I thought a singularity and a black hole were one and the same.

-Will

Naked singularities
https://www.scientificamerican.com/article/naked-singularities-extreme-physics-special/

https://www.scientificamerican.com/...exist-outside-black-holes-in-other-universes/

In terms of art…
https://medicalxpress.com/news/2023-12-visions-nonphysical-world-common-cognitively.html

Now where did Tillinghast hide that Resonator…

 

[Asbo Zaprudder]

The first two links are to articles behind a paywall. Kind of sucks if you don't have subscription.

Singularities are merely a demonstration of our ignorance of the relevant physics as the first article states. It's heartening to know that there might be ways to investigate what happens under such extreme conditions experimentally. As I previously stated, my guess is that the vacuum changes state, which might allow access to other dimensions that are ordinarily compactified and create conditions similar to the initial singularity - energy with the potentiality to be cooled into different forms of matter field excitations with various underlying symmetries and properties.

 

[Asbo Zaprudder]

A new, testable theory that possibly unifies general relativity and quantum mechanics:

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

Space-time would not be quantum in nature, but would instead contain random fluctuations. I don't know if it has anything to say about the behaviour of space-time under extreme conditions. Abstracts and links to the papers below:

The effort to discover a quantum theory of gravity is motivated by the need to reconcile the
incompatibility between quantum theory and general relativity. Here, we present an alternative approach
by constructing a consistent theory of classical gravity coupled to quantum field theory. The dynamics is
linear in the density matrix, completely positive, and trace preserving, and reduces to Einstein’s theory of
general relativity in the classical limit. Consequently, the dynamics does not suffer from the pathologies of
the semiclassical theory based on expectation values. The assumption that general relativity is classical
necessarily modifies the dynamical laws of quantum mechanics; the theory must be fundamentally
stochastic in both the metric degrees of freedom and in the quantum matter fields. This breakdown in
predictability allows it to evade several no-go theorems purporting to forbid classical quantum interactions.
The measurement postulate of quantum mechanics is not needed; the interaction of the quantum degrees of
freedom with classical space-time necessarily causes decoherence in the quantum system. We first derive
the general form of classical quantum dynamics and consider realizations which have as its limit
deterministic classical Hamiltonian evolution. The formalism is then applied to quantum field theory
interacting with the classical space-time metric. One can view the classical quantum theory as fundamental
or as an effective theory useful for computing the backreaction of quantum fields on geometry. We discuss a
number of open questions from the perspective of both viewpoints.

A Postquantum Theory of Classical Gravity? (aps.org)

We consider two interacting systems when one is treated classically while the other system remains quantum. Consistent dynamics of this coupling has been shown to exist, and explored in the context of treating space-time classically. Here, we prove that any such hybrid dynamics necessarily results in decoherence of the quantum system, and a breakdown in predictability in the classical phase space. We further prove that a trade-off between the rate of this decoherence and the degree of diffusion induced in the classical system is a general feature of all classical quantum dynamics; long coherence times require strong diffusion in phase-space relative to the strength of the coupling. Applying the trade-off relation to gravity, we find a relationship between the strength of gravitationally-induced decoherence versus diffusion of the metric and its conjugate momenta. This provides an experimental signature of theories in which gravity is fundamentally classical. Bounds on decoherence rates arising from current interferometry experiments, combined with precision measurements of mass, place significant restrictions on theories where Einstein’s classical theory of gravity interacts with quantum matter. We find that part of the parameter space of such theories are already squeezed out, and provide figures of merit which can be used in future mass measurements and interference experiments.

Gravitationally induced decoherence vs space-time diffusion: testing the quantum nature of gravity | Nature Communications

I'm quite sure that I don't have the mathematical ability to understand these papers fully and comment on them meaningfully.

 

[Will The Serious]

I've read those articles. They did me little good in understanding them. Of course, I don't have the background, but one of them had so many new terms for me that they just sounded like double talk.

strong diffusion in phase-space

long coherence times require strong diffusion

conjugate momenta

diffeomorphism invariant

...
This certainly doesn't mean anything about the theory's viability. From what I can infer, the theory is treating each aspect of space and time with respect to gravity, as independent, but interwoven variables. Each affects the other, but with the ability to separate direct causal relationships. I am skating the edge of understanding my own double-talk here.

In multi-vector, or multi-variable Mathematics, it is standard practice to break out the elements or variables of the equations into pairs, reduce each pair to a single resolved variable, rotate the axis in 2-D, then resolve the new, remaining pairs in similar fashion. Each variable will ultimately have an effects on the outcome, but only an indirect effect upon the other variables. 3-dimensional vector Mathematics is such a process.

But, what if one of those dimensions was inconsistent? What if the fourth dimension contained a random or a yet unidentified pattern?

Perhaps, when just dealing with that one dimension, or when it is calculated with just one other dimension of values, it appears consistent. For example, in a distance-over-time plot. Maybe this could be the case because when only looking at time in that one other dimension, it appears to be regular, at and only at, that one other local coordinate.

If one were to consider the implications of 3-dimensional curved space; broken down into single dimension models, our plot axis may follow these time regularity and we would never be able to test the randomness. But as another dimension was included into the calculations, the plot axis might follow the time regularity lines in multiple directions, consistent with the origin's time rate that matched both other dimension, until one axis or the other crossed an inconsistency in the time dimension. (Such a case would suggest that time was not a single dimension, but possibly two or more dimensions all on its own).

An interesting perspective for the sci-fi writer, and a definite mechanism for the concept of parallel universes. It could also explain time-dilation effects at different locations and velocities in space.

-Will

 

[Asbo Zaprudder]

Yeah, I'm not even going to attempt to wrap my head around those papers. I'll let those with the necessary expertise do that. It obviously passed peer review to get published in Nature. The most encouraging part is that its predictions are testable.

There was a theory back in the late 70s or early 80s about time having three dimensions like space. However, I remember nothing else about it. A theoretician acquaintance thought it had interesting features, but I've never heard it discussed since then.

 

[Will The Serious]

https://www.sciencenews.org/article/gravity-quantum-mechanics-physics-theory
This article distills Oppenheim's ideas down to something a little more digestible.

-Will

 

[Asbo Zaprudder]

I suspect the theory has nothing to state about space-time under extreme conditions, but I'm not sure. I'd also like to know about how the field variation works. Is it purely random like white noise or is its spectrum narrower? The point about non-reversibility might be so incompatible with QM that it eliminates itself as a candidate. The article also doesn't mention how the theory might be similar to Penrose's proposal for state vector reduction bring triggered by gravitational interactions at the scale of the Planck mass (~22 micrograms). The proposal also reminds me of Bohm theory, which makes me suspect it might have a non-local (either superluminal or superdeterministic) element.

 

[publiusr]

The idea of mass being a bit of a variable the farther down you go--and there is more room at the bottom it seems, as per the recent Centauri-Dreams thread--makes me wonder if there are variances in chemicals.

Is one molecule of CO2 really the same as another? While I don't believe in homeopathy at the macros scale--might we see something similar way down?

I seem to remember how heated water might freeze first before lukewarm water.

We as humans can leave a mark upon one another... maybe we can see something similar at the smallest of scales..

 

[Will The Serious]

I seem to remember how heated water might freeze first before lukewarm water.

I've heard this too. I suspect, were you to try this experiment in your freezer: time the freezing of luke warm water in your freezer, then time the freezing of hot water in your freezer, you might corroborate that suggestion. But if you put both trays in your freezer together, they would freeze at nearly the same time, unless you separate the trays.

In the case of the hot tray of water going into your freezer alone vs the warm tray, your freezer has a thermostat that senses the rise in temperature caused by the hot water, and runs the cooling cycle sooner and longer, thus, faster freezing of hot water.

If you live in a colder climate, try the experiment outside where the temperature is less variant, you can store the trays so they don't affect each other's energy levels, and there is no thermostat.

-Will

 

[Asbo Zaprudder]

Yes, it's called the Mpemba effect.