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 . . . . . . . . .

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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 gradational 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?​

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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