Question regarding movement of universe

In summary, the universe is expanding, but it doesn't seem to be moving because its center of mass is constantly changing. There is no center of mass for the universe, and it doesn't seem to have a gravitational force.
  • #1
FeDeX_LaTeX
Gold Member
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I'm no physicist, but I just have some questions...

1) The universe is expanding, correct? This means that its centre of mass is constantly changing, and the centre of the universe is also constantly changing (well... if the universe is spherical, and was increasing in proportion to a sphere). Is this why our Solar System is moving?

(going to post the other questions about neutronium in other thread, since I was given a warning for asking more than 1 question in a thread)
 
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  • #2
You assume that there is a center of mass. That is open to question. Using the well known balloon analogy, where is the center of the SURFACE of a balloon?
 
  • #3
The surface of the universe? I don't know... that is confusing. Does the universe have a gravitational force? And does it move?

I was just thinking that, if it *did* move, then that would imply that there would be an object having a greater mass than the universe due to gravitational force.

...Wait, how can something not have a centre of mass?
 
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  • #4
FeDeX_LaTeX said:
The surface of the universe? I don't know... that is confusing. Does the universe have a gravitational force? And does it move?

I was just thinking that, if it *did* move, then that would imply that there would be an object having a greater mass than the universe due to gravitational force.

...Wait, how can something not have a centre of mass?

Think of the balloon analogy for a 2d universe. The universe is on the surface of the balloon, which is expanding. Points on the balloon move away from each other as it expands. Even though the universe is expanding, it doesn't make sense to talk about motion of a centre of mass.

Torquil
 
  • #5
1) The universe is expanding, correct? This means that its centre of mass is constantly changing, and the centre of the universe is also constantly changing (well... if the universe is spherical, and was increasing in proportion to a sphere). Is this why our Solar System is moving?

The universe IS expanding but that says nothing about possible movement of it's "center of mass". Every distance point moves away from evry other distant point; nearby points are usually held firm by gravitational attraction.

A "center of mass" for the universe depends on what model of the universe you are considering...a practical problem is that 99.9999...% of the universe is probably not observable..meaning we have no causal contact, no means to detect it.

Each increment of space not bound by gravitational attraction apparently gives rise to new space...due to the cosmological constant, maybe dark matter. That new space is "empty" and has only zero average energy, quantum fluctuations, and so has no inherent mass nor energy nor I would guess pressure...all gravitational components in general relativity. That means insofar as we know that the total mass and energy in the universe is constant...conservation of mass energy...

This question should be moved to the cosmology forum...evolution of the universe..
 

FAQ: Question regarding movement of universe

What is the current theory about the movement of the universe?

The current theory is known as the Big Bang theory, which states that the universe began as a single point and has been expanding ever since. This expansion is also believed to be accelerating due to dark energy.

How do scientists measure the movement of the universe?

Scientists use a variety of methods to measure the movement of the universe, including the redshift of galaxies, the cosmic microwave background, and the distance and velocity of objects in space.

Is the movement of the universe uniform or does it vary?

The movement of the universe is not uniform and varies greatly depending on the location and distance from the observer. This is due to the gravitational pull of different objects in space and the expansion of the universe itself.

Can the movement of the universe be affected by external forces?

While the universe is constantly expanding, it is also constantly being affected by gravitational forces from other objects in space. These forces can cause objects to move towards or away from each other, altering the movement of the universe as a whole.

What implications does the movement of the universe have for the future of our universe?

Based on current observations and theories, it is believed that the universe will continue to expand indefinitely. However, the rate of expansion may change over time due to the influence of dark energy and the gravitational forces of other objects. Ultimately, the movement of the universe will determine the fate of all galaxies and stars within it.

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