Expanding Universe (an interestin mind experiment)

In summary, the conversation discusses the concept of measuring the expansion of the universe based on relativity. It suggests that depending on an observer's location, they may perceive either expansion or contraction. The example of a yellow ball being squeezed is used to illustrate this idea. The conversation also raises the question of whether other dimensions or universes could be responsible for the universe being squeezed. However, the concept of a homogenous and isotropic universe at large scales complicates this idea. The conversation ends with a comparison to a raisin muffin in an oven and the explanation of redshifts in relation to cosmological expansion. Overall, the conversation explores the possibility of measuring the expansion of the universe through different perspectives and scenarios.
  • #1
pfontec
3
0
Try thinking about measuring the expansion of the universe based on relativity. That is to say that depending on where you are located in the universe you might measure expansion or you might measure contraction!
Think about this.
The observer is placed anywhere inside of a giant ball of yellow "play dough". throughout the inside of the yellow ball are many little balls of different colored "play dough" representing galaxies.
Now something starts to squeeze the yellow ball.
Now depending on where the observer is located. He will percieve the colored "play dough" (the galaxies) expanding or he we percieve the galaxies contracting.
Can it be that our universe is being sqeezed by other dimensions (other universes?

I would appreciate any comments
Thank You
Pat Fontecchio
 
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  • #2
pfontec said:
Try thinking about measuring the expansion of the universe based on relativity. That is to say that depending on where you are located in the universe you might measure expansion or you might measure contraction!
Think about this.
The observer is placed anywhere inside of a giant ball of yellow "play dough". throughout the inside of the yellow ball are many little balls of different colored "play dough" representing galaxies.
Now something starts to squeeze the yellow ball.
Now depending on where the observer is located. He will percieve the colored "play dough" (the galaxies) expanding or he we percieve the galaxies contracting.
Can it be that our universe is being sqeezed by other dimensions (other universes?

I would appreciate any comments
Thank You
Pat Fontecchio
If the universe is being squeezed, then it would have to be squeezed by gravity. But observation indicate a homogenous, isotropic universe at large scales. So there does not seem to be any mechanism for squeezing.
 
  • #3
Let us assume that the yellow ball is being sqeezed equally from all directions.
And let us assume that the yellow ball is compressing.
There is at the exact center of our ball a infinitesimally small point at which there can be no compression, just like the epicenter of an Earth quake.
from the exact moment that compression starts ,there is, at that exact moment, expansion away from the epicenter equal in all directions.
So if the observer were closer to the epicenter what would he observe?
 
  • #4
Don´t think of it as play dough, think of it as a raisin muffin in an oven. As the muffin itself expands, the raisins expand with the muffin giving all the raisins a expansion movement from what ever raisin you are standing on.
 
  • #5
But in a universe with a finite speed of light [wrt local reference frames], cosmological expansion will be apparent to all observers. It is difficult to explain redshifts > 1.66 without cosmological expansion.
 

What is the Expanding Universe theory?

The Expanding Universe theory is the idea that the universe is constantly growing and stretching outwards. This means that the distances between galaxies and other objects in space are getting larger over time.

What evidence supports the Expanding Universe theory?

One of the main pieces of evidence for the Expanding Universe theory is the observation of redshift in distant galaxies. This indicates that these galaxies are moving away from us, supporting the idea of an expanding universe. Additionally, the cosmic microwave background radiation, leftover from the Big Bang, also supports this theory.

How does the Expanding Universe theory relate to the Big Bang theory?

The Expanding Universe theory is closely related to the Big Bang theory, as it suggests that the universe began as a single point and has been expanding ever since. The Big Bang is the widely accepted explanation for the origins of the universe and is supported by various observations and experiments.

What is dark energy and how does it relate to the Expanding Universe theory?

Dark energy is a hypothetical form of energy that is thought to be responsible for the accelerating expansion of the universe. This means that the rate of expansion is increasing over time, rather than slowing down. It is an important component of the Expanding Universe theory and is still not fully understood by scientists.

What are some potential implications of an expanding universe?

The Expanding Universe theory has significant implications for our understanding of the universe. It suggests that the universe is not infinite and will continue to expand indefinitely. It also raises questions about the ultimate fate of the universe and whether it will eventually collapse in a "Big Crunch" or continue to expand forever.

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