Interactions in the universe are really important for how galaxies form. Here’s a breakdown of the main ones:

1. Gravitational Force:

   • This is the strongest force when it comes to big things like galaxies.
   • It makes up about 80% of the stuff in the universe, and a lot of that is dark matter, which we can’t see.
   • Gravity pulls gas and dust together, which helps create stars and whole galaxies.

2. Electromagnetic Interaction:

   • This force helps cool down gas clouds.
   • When these clouds cool, they can stick together and form stars.
   • It also creates the light that stars give off, which helps shape how galaxies look.

3. Weak Nuclear Force:

   • This force plays a big role inside stars.
   • It helps create heavier elements, which are really important for the growth of galaxies.

4. Strong Nuclear Force:

   • This force holds protons and neutrons together in atoms.
   • It helps determine how many different elements there are in galaxies.

In short, these forces work together to shape how galaxies look and what they are made of.