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

Discussion in 'Science and Technology' started by Will The Serious, Feb 7, 2023.

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The principle of least action is the cornerstone of modern physics. However, there is no real justification for using it other than it appears to work. A related alternative is Fisher information theory, which can be used to generate new physical principles. When it comes down to it, they're probably just slightly more sophisticated forms of dimensional analysis (figuratively speaking).

Last edited: Feb 13, 2023
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2. ### Will The SeriousCaptainCaptain

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I was just thinking about Gödel's assertion that a rotating Universe would prove time travel. I am familiar with Gödel's Incompleteness Theorem, and think it is brilliantly elegant. What I was wondering about was the idea that a beam of light might travel across the Universe to return to its point of origin in the past. If the rotating Universe was also expanding, then such a beam of light would not ever return to its point of origin because the point of origin would never remain within the same concentric circumference. It would forever travel a spiraling infinity.

For a Universe of cosmic dimension, the limitations of speed would mean the rotation would have to be nearly imperceptible at its outer edges. However, given an ever mutable connecting medium or matrix of matter, the inner elements could have a greater angular speed.

-Will

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I suspect Gödel's aim was less to show that general relativity's solutions permitted time travel than to demonstrate to his friend Einstein the shortcomings of his theory. Ever the logician, Gödel even fretted over the inconsistencies of the US constitution. He was quite an odd person and the circumstances of his death were tragic.

ETA: The description of the Gödel metric on Wikipedia (https://en.wikipedia.org/wiki/Gödel_metric) suggests that indeed it was more an exercise in logic than an attempt to describe our universe or to show that time travel is possible within it. The way that the metric is constructed is not applicable to our universe.

Last edited: Feb 18, 2023
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4. ### Will The SeriousCaptainCaptain

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https://bigthink.com/hard-science/nothing-exist-quantum-foam/
This statement seems to conflict with the final experiment described at the end of the article.
I am sure the scientist who have conducted this experiment know what they are doing, but if radiation energy can exist in a perfect vacuum, no physical material what so ever to conduct the wave, why would lowering the temperature change that?

If these plates move together for for the reason projected, that wave/particle energy forms "randomly" out of nothing, what stops these things from trying to form in between the gap of the metal plates equally as on the outside? My expectations would be the opposite of the projected hypothesis. I would expect the plates to be pushed apart by the occasional larger wave/particle and that the radiation from the material of the inner walls of the chamber would tend to push the plates together. But then, if radiation from the material of the chamber could push on the plates, then the plates could likewise push back, which would mean, they also push on each other. Do these plates not suffer from a static magnetic attraction? Would they not create a magnetic field around them that could act like fluid flowing through a restriction and cause them to move together through a short of electromagnetic Bernoulli Effect?

So many possible reasons those plates move together.

-Will

Last edited: Feb 19, 2023

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The temperature is lowered to reduce the emitted thermal radiation (as actual photons) to a minimum. The vacuum energy in the enclosure consists of virtual photons (, continually popping into and out of existence.
They do, but the wavelengths of their wavefunctions are effectively restricted to what will fit in the cavity as standing waves. The Wikipedia article on the Casimir Effect gives a good description and alternative interpretations with equivalent results.
Only if they are magnetised, which I'm sure is not the case here assuming the experimenters are diligent. The plates also don't carry an electrostatic charge if they are correctly grounded.
Relativistic van der Waals force, rather than magnetic force, is another interpretation.

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6. ### Will The SeriousCaptainCaptain

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My education is very limited with regard to chemistry. I have had physics in high school, physics in my bachelor's program and basic electrics as part of my computer science degree. It is my understanding that it is an electrical force that holds Atomic particles together to form molecules. I can't see that being completely null. One of the experiments we conducted in physics was to charge a two part foil strip that was folded in half. The electrons that crowded into the charge foil, forced the foil strips apart. Conversely, if one were to remove the electrons, the preeminent proton heavy foil would also cause a repulsion, but if there was an imbalance, even a miniscule one, the force of attraction would be more than adequate to cause an effect over several centimeters of distance.

I am sure the scientists were as diligent as they could be. Just how diligent can that be in an experiment like this one?

Funny thing about this article is it comes to me on the heels of writing one of my fan fiction episodes where a professor of Gravitronic is speculating on the nature of gravity looking more like a vast cloud of soap bubbles where the soap membranes intersect to create threads of tension between the nodes of multiple bubbles coming together and forming matter. This would cause an attraction, or more like a spring-like resistance to changes in distance, such that an effect of attraction would appear to resist expansion. Lots of techno-babble, but fun to speculate on.

-Will

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Yeah, I'm talking about net electrostatic charge on the conductive plates. Van der Waals forces are the result of mutual repulsion between the electron clouds of atoms.

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The Other Realms
Nice reference was that TNG?

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SoCal
Yes, Remember Me

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Ship, meet bottle.

11. ### Will The SeriousCaptainCaptain

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I have been considering this statement, as well as many others recently, and I would like to revisit its basic concepts.

I am still lost around the current thinking about what gravity is and how it works, but some new ideas that I have recently come to understand:
1st - (and not really new), acceleration is basically a change in momentum.
(Question: Does that include a change in mass where there is no change in speed or direction, or have I got it wrong and acceleration is a change in velocity alone?).

2nd - gravity is not considered a force, yet it is often called an acceleration. (Either it is a change in momentum or just a change in velocity).

3rd - (and this is also classic mechanics), there is no such thing as centrifugal force; it is centripetal force. Centripetal force has no specific cause, only a force that pulls or pushes towards a center point, thus changing a momentum. I call it a change in momentum because inertia is the state that centripetal force works against. A spinning object is therefore in constant acceleration even though its speed doesn't change. Its velocity is always changing.

In the case of rotational motion, to the observer on the inner wall of a spinning ring, how would the acceleration of mass not look like gravity? The farther from the center of rotation the mass gets, would represent an increase in an opposing force to its momentum, so would that not look exactly like the acceleration of gravity? I suppose an over in free fall between a smaller radius to a larger radius, would not observe a relative acceleration in speed towards the appearance ground, or would it?

-Will

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1. Acceleration is rate of change of velocity. Both acceleration and velocity are vector quantities. If the speed of an object remains constant but its direction changes, this change in velocity implies an acceleration.
2. Gravity is a force in Newtonian physics. In General Relativity, it is attributed to the curvature of spacetime by mass-energy.
3. As with Coriolis force and Euler force, centripetal force is a fictitious force caused by choice of a rotating (and thereby accelerating as the velocity vector is changing) frame of reference. This is obvious to an observer in an inertial frame of reference that is not undergoing acceleration. Centrifugal force (a reaction to centripetal force) feels like gravity due to its accelerating effect on mass, but objects dropped do not accelerate as they would in a gravitational field.

Modern Physics usually uses Lagrangian mechanics to examine the energies in a system rather than Newtonian mechanics, which deals in forces. This is seen as a more natural way of performing calculations as it appears to provide deeper insights when combined with Hamilton's principle of least action.

Last edited: Feb 26, 2023
13. ### Will The SeriousCaptainCaptain

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This is where I can't help but wonder. If we were to use the ground (surface of the earth or inside of a rotating cylinder) as our frame of reference, then a dropped object in the cylinder would appear to accelerate toward the ground. Consider that a tangential inertia of the falling object would be constant (velocity constant upon release from the influence of centripetal force), the rate of change of the closing distance between the ground and the object would increase as the object traveled along its tangential path. Initially, that path is parallel with the movement of the ground, near zero closing velocity. As the object travels at the tangential velocity to the circumference of the inner radius, it moves into a more and more perpendicular path to the outer radius. This means the apparent closing speed of the object and the ground increases with time.

I haven't done the math, but I'm sure it won't match the acceleration of gravity but it will be an acceleration during free fall, with no acting force upon the object. However, there is an acting force upon the ground.

-Will

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What one might imagine would happen is no substitute for mathematics and/or experiment. However, I'm not going to enter into a debate about this. It's not worth our time to do so. Trying to describe such things in English rather than mathematics is a fruitless endeavour. There might well exist Physics sandbox games that can simulate such things and provide a greater insight, but I have no experience of any.

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16. ### Will The SeriousCaptainCaptain

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Excellent videos. Thanks for those.
I disagree. Mathematics is great for Mathematicians and to present some concrete model, but if it can't easily be imagined and described in words, how can you know the math is telling you what you want? Some math formula are easily derived from the dynamics of physical phenomenon, but others don't have such obvious analogous connections to the concept and they may not be easy to see from the calculations what that dynamic is telling us. Still other formula may perfectly describe outcomes consistent with experimental results, yet completely miss the truth of the relationships they describe. Math is an important tool, but it isn't any more perfect than the logic that derives it.

-Will

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Something I seem to remember reading about centripetal force—if you were to do an actual slingshot around a black hole…you would not be slung against the wall away from the black hole…but the inner one somehow, IIRC.

I still think a magnetar is more dangerous in that it’s magnetic field really does want to yank you out of an orbit and inwards the way most think a black hole’s gravity would.

We’re our Sun instantly replaced by a black hole of the same mass—our orbit would not be affected one kit (we’d begin to get cold starting 9 minutes later.)

The directionality change near a black hole gets me. Farther down—there is only the downward gradient allowed…that I can understand.

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Besides it magnetic pull, mere proximity to a magnetar is lethal. Its magnetic field stops chemistry working properly due to the effect on electron orbitals. This effect extends outward for several thousand kilometres.

Some things cannot be described properly in words that deal with human experience. Examples are the quantum realm and dimensionality beyond three. We make comforting word pictures for things much smaller than the wavelength of light that we cannot see directly or for spaces that our brains are not evolved to comprehend directly. It's no wonder that there are so many competing descriptions for the mathematics of quantum mechanics nor that we struggle to accept what it is telling us about reality.

Last edited: Feb 27, 2023

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I have heard it said we could have Star, planets in a universe with no weak nuclear force…but no atom bombs and such.