Space does not stretch: True or false

[Gibsense]

The expansion of the universe is often described as space "stretching," but it's a bit more nuanced than that. In cosmology, space itself doesn't stretch like a rubber sheet—it expands in a way that increases the distance between objects without them physically moving through space.

One way to think about it is that new space is being created between objects, rather than existing space stretching thinner. This is why galaxies appear to move apart from each other, even though they aren't actively travelling through space in the traditional sense.

Quantum field theory suggests that even "empty" space is filled with quantum fluctuations, where virtual particles pop in and out of existence. Additionally, general relativity treats space as a dynamic entity that can bend, stretch, and expand. This means that space isn't just an absence of matter—it's a fundamental component of reality.

In quantum field theory, the vacuum energy of space is estimated to be incredibly high—potentially around (10^{113}) joules per cubic meter. If we convert this into mass, it would be roughly (10^{93}) grams per cubic meter. However, this value is vastly larger than what we observe in cosmology, leading to the famous "vacuum catastrophe"—a huge discrepancy between theoretical predictions and actual measurements.

 

[Catastrophe]

There may be a semantic difficulty here . . . . . . . . .

Google Search

Cat

 

[Gibsense]

There may be a semantic difficulty here . . . . . . . . .

Exactly so. Thinning is not the same as adding. If we do not get the ducks in a row how are we to understand the universe?

 

[Catastrophe]

Exactly so. Thinning is not the same as adding. If we do not get the ducks in a row how are we to understand the universe?

I do not understand what you mean. Did you read my reference?

The semantic difficulty relates to Universe and (observable) universe.

Molecules can come together to form a human being) contrary to entropy. In the longer term, death restores the entropy by decomposition of the body into many more disordered molecules.

Cat

 

[Gibsense]

I do not understand what you mean. Did you read my reference?

I had not read that but have done so now. It illustrates my point that the loose use of 'stretching' is wrong. There is no evidence for 'stretch', it is just a poor analogy, potentially misleading.

 

[Catastrophe]

I do not like the word "stretching", as it implies elasticity. This seems mirrored to some extent in the reference:

The expansion is not just a static stretching of space, but rather an active process driven by dark energy, which is causing the expansion to accelerate.

Cat

 

[Gibsense]

"The expansion is not just a static stretching of space, but rather an active process driven by dark energy, which is causing the expansion to accelerate."
or,
The expansion is not just a static stretching of space, but rather an active process driven by, God knows what - it may be some magical influence of the Devil, causing the expansion to accelerate.

 

[Catastrophe]

The expansion is not just a static stretching of space, but rather an active process driven by, God knows what - it may be some magical influence of the Devil, causing the expansion to accelerate.

It is driven by entropy.

Molecules confined in a small space are more orderly than molecules which escape into a lower pressure environmeent where they can move around much more freely.

This is shown by the fact that, if you compress steam it will eventually turn to liquid water. Liquid water is more ordered than gaseous water.

Yes, compressing steam can cause it to turn back into water, but it's not simply a matter of compressing it to a smaller volume than the original water. When steam is compressed, it undergoes a phase change back to liquid water, and the pressure and temperature will increase as the compression continues.

Elaboration:

• Phase Change:
  Steam is water in its gaseous state. When pressure is applied to steam, it's forced to condense back into liquid water,

Source: Google.

Steam (water vapor) has a higher entropy than liquid water at its boiling point. This is because steam molecules have more freedom of movement and a higher degree of disorder compared to the more tightly packed and ordered molecules in liquid water.

Key points about entropy of steam and water:

• Disorder and Entropy: Entropy is a measure of disorder or randomness in a system.
  
  
• Liquid vs. Gas: Liquid water has a lower degree of disorder than steam because the molecules are more tightly bound and less free to move.
  
  
• Boiling Point: At the boiling point, the entropy of steam is higher than that of liquid water.
  
  
• Temperature: Both liquid water and steam exhibit changes in entropy with temperature.
  
  
• Phase Changes: Entropy changes during phase transitions (like vaporization of water to steam). For example, the entropy increases significantly during the vaporization of water to steam at its boiling point.

Cat

 

[jhixon]

Space doesn't stretch. Think of space in terms of water and the fluidity of water or the three forces with quantum stuff floating around, meaning that gravitational waves are created by the object/matter displacing space, just like sticking your fist in a container of water, the water level rises or expands out. When matter is created, it pushes space/the three forces out to occupy that area, so the space must expand outward. The contraction of space occurs when black holes breakdown matter stealing its electrons/energy and expelling out pieces that are bursting as Hawking radiation from decay. It's this cosmic balance that is symmetry in our universe. Thinking in terms of space stretching, twisting etc. is a two dimensional viewpoint and space is fluidity of forces that are everywhere in this universe..

 

[Catastrophe]

Space does not stretch: True or false?​

Google Search

This seems to be a fairly comprehensive reply.

• "Stretching" is an analogy:
  While the expansion can be likened to stretching a rubber sheet, it's not accurate to think of space as a physical, stretchy substance. The expansion is a change in the geometry of spacetime, not a physical stretching of a material.

Cat

 

[Gibsense]

It is driven by entropy.

Molecules confined in a small space are more orderly than molecules which escape into a lower pressure environmeent where they can move around much more freely.

This is shown by the fact that, if you compress steam it will eventually turn to liquid water. Liquid water is more ordered than gaseous water.

You have quoted me out of context in order to write the above. Let me be clear, I was showing up the concept named "Dark Energy" as a near-useless explanation for Cosmic expansion/acceleration. I have previously attempted to show that acceleration is a misinterpretation of hyperbolic geometry and suggested a possible expansion is due to space added as a consequence of a black hole's extreme spin.

But to address your point above, where you say expansion drives entropy. All of your examples to show how entropy works make my point that the reverse is true. That is, entropy occurs because of expansion.

It is clear and very obvious that molecules (in your example above) cannot escape into a lower-pressure area unless there is a lower-pressure area to escape into. I thought that might be your idea (that entropy caused expansion), but was not sure, as until now you have not stated it, but again, I may be guessing wrongly, and you are just stating a position made by others. Maybe we can consider this further.

 

[Gibsense]

This seems to be a fairly comprehensive reply.

If I recall correctly, your Google search posted a comment that space neither stretches nor is added to. At first sight, this seems silly - that it has to be one or the other. However, there is a logical scenario where this may be true:
I cannot get my AI to respond currently so this is raw but Grammarly still works

1. Let's keep the hypersphere model where the surface of a ball is a hypersphere and the hypersphere is our universe's 3d space
2. Our environment, then, is within the 3d space of a hypersphere, which we can assume to be a static "just is" space
3. This is the crucial Bit: Within the hypersphere space, there is a "now" (in hypersphere format) expanding and hence expanding space within existing space. For example, a shockwave in a goldfish bowl where the shock starts at the centre of the bowl in a spherical shock outwards.
4. BUT WAIT, there's more, the Shock wave/Timewave continues until engaging the static boundary of the 'Mother Hypersphere. It then rebounds and heads inwards (contracting space). That is, it hits the glass of the Goldfish Bowl, and the shockwave "now" heads back inwards to the origin only to make another BB
5. I suppose we can imagine the process continuing

If I can get the AI working again, I can ask it how to investigate such a bouncing universe and if it comes up with anything reasonable, start a new thread

 

[Catastrophe]

Are you referring to (Quote):

The expansion is a change in the geometry of spacetime, not a physical stretching of a material.

Cat

 

[Catastrophe]

If I recall correctly, your Google search posted a comment that space neither stretches nor is added to. At first sight, this seems silly - that it has to be one or the other. However, there is a logical scenario where this may be true

Gibsense, does this help?

Google gives:

AI Overview

The statement "space neither stretches nor is added to" is generally true within the framework of General Relativity. The universe expands because the space-time fabric itself is expanding, not because existing space is being stretched or new space is being created.

Incidentally, Google also gives:

The aether, as it was historically conceived, does not expand. The concept of aether was a theoretical medium thought to fill space and transmit light, but it was disproven by experiments like the Michelson-Morley experiment. Instead, the universe's expansion is attributed to dark energy, a mysterious force causing the universe to accelerate its expansion.

and

Spacetime fabric and aether are not the same. While the term "spacetime fabric" is often used to help visualize spacetime, it's a metaphorical description, not a literal medium like the old concept of aether. Aether was once thought to be a medium through which light waves traveled, while spacetime is a mathematical model that combines space and time.

Cat

 

[Gibsense]

Are you referring to (Quote):

Your quote started me off, but having got the AI working again, it directed me to a site called Pysics Stack Exchange, which incorporates the Astronomy Stack Exchange, which I was told I was already a member. Upon sorting my password out I found that the Question - why not a hypersphere (or equivalent) had been answered 7+ years ago as yes it fit all the numbers and would explain dark energy.
So right now I am completely deflated batting on about something already verified more or less. Wasting mine and everyone's time. Heck I may have sparked off the discussion years ago. Geez

Sorry

 

[jhixon]

Newton said that a theory only matters when it's tested, if the results don't fit your theory, then modify or start over. Trying to move forward in understanding is not a waste of time. We are all wrong until we are proved right by the universe's answers. Keep a positive attitude.