Galaxies still collide.

The expansion of the universe doesn't mean that galaxies cannot collide. There are at least two galaxies. That is coming to the Milky Way. The Large Magellanic Cloud will impact the Milky Way in 2,4 billion years. And Andromeda galaxy collides with the Milky Way after 4,4 billion years. 

That thing means that there are two versions of the universe. The thing is that the galaxies in the local clusters turn into one entirety. And then. Galaxies in superclusters turn into one entirety. Because their mutual gravity wins dark energy.

There are two geometries in the universe. Local and global geometry. Local geometry is the thing. That we see in large galaxy clusters. 

Global geometry means. The universe's geometry as an entirety. 

The fact is that in local geometry gravity always wins. But on a global scale, the dark energy wins. The large-scale models show that the universe expands. However, the small-scale model can be different. And in small-scale models the galaxies in local galaxy clusters or groups will come together. In local galaxy clusters, the internal gravity of those clusters wins the expansion and that causes the galaxies will collide. All galaxies pull material from around them. 

That increases their mass. And expands the galaxy's gravity field.  When galaxies collide. That new structure's mass is the same as both galaxies' mass. 

That increases the size of the gravity field or gravity pool. Gravity is interaction and the same way distant galaxies pull the Milky Way and Andromeda galaxies to them, as Milky Way and Andromeda pull those galaxies to our direction. 

Material is not homogenously spread all over the universe. Things like the cosmic web make modeling those kinds of systems very difficult. 

There are interactions between galaxies, galaxy clusters, and globular clusters. And the fields in those cosmic web structures. The gravity effect forms those complicated structures in the universe. Gravity is the strongest interaction at long distances. 

But that is not the only interaction in the universe. There are other interactions like electromagnetism. Those interactions are losing to gravity. But they have effects in short distances.  

That means that things like gravitational effects are not the same everywhere. Galaxies are in clusters. Those clusters are like bubbles. 

In those bubbles, there are local clusters. And superclusters, groups of local clusters. The mutual gravity in those clusters pulls galaxies together. 

Those bubbles form galaxy clusters. In galaxy clusters, the internal gravity of those structures pulls their galaxies together. First, the local clusters melt into large galaxies. And finally, those superclusters melt into single giant galaxies. The thing that the universe's expansion and the decrease of the energy level causes is that. Entropy in the system rises. That causes two effects. 

First, the entropy disturbs information more than in the young universe. But. Otherwise the energy levels in those fields are lower. That means the gravity pools around the galaxies turn larger. The gravitational fields affect a longer distance because there are not so powerful disturbing fields. The gravity centers are larger but the space between those large galaxies will be cold and dark. 

The energy level difference in and outside those galaxies is higher than it is in the modern universe. That causes situations where material in galaxies vaporizes more than in the modern universe. Galaxies send radiation stronger than in the modern universe. But there is less material and radiation between galaxies. 

That tells that there was some kind of turbulence. Or something that was denied. The material spread homogeneously over the universe.  There were some kind of gravity centers. That could be primordial black holes. That started the form of those galactic clusters. 

https://bigthink.com/starts-with-a-bang/why-galaxies-still-collide-expanding-universe/

https://www.sci.news/astronomy/large-magellanic-cloud-milky-way-collision-06788.html

https://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision

https://www.sciencealert.com/a-supermassive-black-hole-is-on-a-collision-course-with-the-milky-way

Spiral form's role in nature and spacetime.

We have all seen spirals. We all know what that geometrical shape looks like. Spirals are the mathematical introduction of the whirls. The whirl around the center makes things like tropical storms possible. When tropical hurricanes form the interaction between falling and rising air in the middle of the whirl makes the air pillar that the Coriolis force starts to turn. In a hurricane, there is the falling air pillar that rising air surrounds. 

That low pressure forms a whirl that denies that the rising air pillar cannot spread. And then. That air spiral starts to pack air against the air pillar that forms the eye of the storm. In the diagram, you can see, that there is a rising air around the falling air. 

That thing makes energy fall into the middle of the whirl. And because the falling air has a lower temperature than the air spiral around it, that packs the spiral against cold air. If there is no cold air channel the whirl will be broken. The cold air conducts energy. Out from the hurricane's eye and denies the standing wave formation. 

Could the geometrical shape of the universe be a large flat spiral rather than a plate or sphere?

There is a very huge whirls or spirals in the universe. Those spirals are spiral galaxies and black hole material disks. The spiral structure interacts same way as the air spiral or whirl interacts in the atmosphere.

The spiral denies that things like black holes will not release their energy away. The outer structure in a spiral or whirl packs energy against the inner structure. The thing that makes the black hole act as it should is the wormhole the structure, that takes energy out from it. The spiral around the black hole presses the structure with the power of the entire spiral power fields.  The black hole is destroyed if that spiral is lost. Without it. A black hole sends energy back to space. 

The spiral dumps energy into the black hole.  But in the same way, something must remove the standing wave from inside the black hole. The black hole expansion continues until it can transport energy into those wormholes that might leave from the same point as the black hole's relativistic jets. 

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When we think that the spirals are repeating and repeating structures and forms from cosmic megastructures to tropical storms, we can ask one thing: Could the quantum field be around elementary particles rather than the spiral shape? The quantum field can form a ball-shaped spiral around those particles. 

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Can the universe's geometrical shape be spiral? 

"The local geometry of the universe is determined by whether the density parameter Ω is greater than, less than, or equal to 1. From top to bottom: a spherical universe with Ω > 1, a hyperbolic universe with Ω < 1, and a flat universe with Ω = 1. These depictions of two-dimensional surfaces are merely easily visualizable analogs to the 3-dimensional structure of (local) space. " (Wikipedia, Shape of the Universe)

Only if Ω>1 the gravity win and the ultimate fate of the universe is the big crunch. But there is the possibility. That none of those geometrical shapes of the universe are not homogenous. It's possible. That there are holes or lower energy fields in those structures. Those things can make the universe look like a spiral. But that is a hypothesis. 

When we think that the spirals are repeating and repeating structures and forms from cosmic megastructures to tropical storms, we can ask one thing: Could the quantum field be around elementary particles rather than the spiral shape? The quantum field can form a ball-shaped spiral around those particles. 

When we think that the black hole pulls material in it in a spiral form there can be a little hole in the power field. If that hole exists that means that the black hole's material jets are the place, where we should look for the wormholes. In this model the relativistic jets involve wormholes. In gravitational models, wormholes are the channels through the Higgs field. The biggest spirals in the universe are unknown. It's possible that around the entire universe is a giant spiral. 

So what if the universe's geometric shape is a flat giant spiral? That thing means that cosmology is wrong because the geometrical shape of the universe is wrong. But does that thing cause something to the ultimate fate of the universe? 

When we think about the Coriolis force, that effect makes the whirl or spiral turn in the same direction on Earth. So if all galaxies will rotate in the same direction that means that they would be in, or, on the layer that moves into the same direction. That is one thing that could support a thing called dark flow. The dark flow is the hypothesis that all galaxies move in the same direction. That means that the universe would have the center of the gravitational object, which puts all other objects orbiting it. 

https://en.wikipedia.org/wiki/Coriolis_force

https://en.wikipedia.org/wiki/Dark_flow

https://en.wikipedia.org/wiki/Shape_of_the_universe