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

[Asbo Zaprudder]

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).

 

[Will The Serious]

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

 

[Asbo Zaprudder]

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.

 

[Will The Serious]

https://bigthink.com/hard-science/nothing-exist-quantum-foam/

What would happen if scientists took a container and removed all the air out of it, creating an ideal vacuum that was entirely devoid of matter? The removal of matter would mean that energy would remain. Much in the same way that the energy from the Sun can cross to the Earth through empty space, heat from outside the container would radiate into the container. Thus, the container wouldn’t be truly empty.

This statement seems to conflict with the final experiment described at the end of the article.

the Casimir Effect, named after Dutch physicist Hendrik Casimir. The effect goes something like this: Take two metal plates and put them very near one another in a perfect vacuum, separated by a tiny fraction of a millimeter. If the quantum foam idea is right, then the vacuum surrounding the plates is filled with an unseen flurry of subatomic particles blinking into and out of existence.

These particles have a range of energies, with the most likely energy being very small, but occasionally higher energies appear. This is where more familiar quantum effects come into play because classical quantum theory says that particles are both particles and waves. And waves have wavelengths.

Outside the tiny gap, all waves can fit without restriction. However, inside the gap, only waves that are shorter than the gap can exist. Long waves simply cannot fit. Thus, outside the gap, there are waves of all wavelengths, while inside the gap there are only short wavelengths. This basically means that there are more kinds of particles outside than inside, and the effect is that there is a net pressure inward. Thus, if the quantum foam is real, the plates will be pushed together.

Scientists made several measurements of the Casimir effect, however it was in 2001 when the effect was conclusively demonstrated using the geometry I have described here. The pressure due to the quantum foam causes the plates to move. The quantum foam is real. Nothing is something after all.

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

 

[Asbo Zaprudder]

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?

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.

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?

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.

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?

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.

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 sort of electromagnetic Bernoulli Effect?
So many possible reasons those plates move together.

Relativistic van der Waals force, rather than magnetic force, is another interpretation.

 

[Will The Serious]

The plates also don't carry an electrostatic charge if they are correctly grounded.

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

 

[Asbo Zaprudder]

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.

 

[Gingerbread Demon]

It's a sphere with a diameter of 700 m.

Nice reference was that TNG?

 

[NCC-73515]

Yes, Remember Me

 

[Asbo Zaprudder]

Ship, meet bottle.

 

[Will The Serious]

Centripetal/centrifugal acceleration might superficially feel like gravitational acceleration to someone standing on the inner surface of a ring but it's not a gravitational field. A dropped object would not move as it would on a massive body such as the Moon or Earth.

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

 

[Asbo Zaprudder]

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.

 

[Will The Serious]

feels like gravity due to its accelerating effect on mass, but objects dropped do not accelerate as they would in a gravitational field.

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

 

[Asbo Zaprudder]

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.

 

[Asbo Zaprudder]

Here are some YouTube links that might be useful:

 

[Will The Serious]

Excellent videos. Thanks for those.

Trying to describe such things in English rather than mathematics is a fruitless endeavour.

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

 

[publiusr]

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.

 

[Asbo Zaprudder]

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.

 

[publiusr]

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

 

[Asbo Zaprudder]

Universes with no weak force might still have stars and life (sciencenews.org)

I haven't read the original paper so I'm not sure whether it explains why the electromagnetic force can exist without the weak force. In our Universe, the current understanding is that the electromagnetic and weak forces are two aspects of a unified electroweak force, and that they emerged during a phase change as the Universe cooled. According to the electroweak theory of Glashow, Salam and Weinberg, the electroweak field in the early Universe had four types of massless gauge bosons. This gauge symmetry spontaneously broke into the U(1) symmetry of electromagnetism with a single massless boson, the photon, and the SU(2) symmetry of the weak interaction with three bosons (W+, W-, and Z0), which have mass due to the Higgs mechanism. The photon does not couple to the Higgs field and remains massless as a result. At even higher energies, it is believed that the electroweak and strong forces are unified, and at higher energies still, also gravity. However, some theories posit that the symmetry breaking between the four forces happened at the same energy. Perhaps I will disappear down the rabbit hole to read the paper sometime, but I do not feel so inclined at the moment.