We can see predictions of galaxies forming, of galaxies colliding into each other, of new solar systems.

Formation of groups, clusters and superclusters Gravitational attraction pulls galaxies towards each other to form groups, clusters and superclusters.

There are places where there are no galaxies and there are places where there are thousands of galaxies clumped together, right.

Galaxies form, and generations of stars form in those galaxies, and around one star, at least one star, is a habitable planet.

And we call them active galactic nuclei.

In one of these galaxies

Distance galaxies were moving away from us.

So all of these galaxies are moving.

It is plausible that the galaxies within our observable universe represent only a minuscule fraction of the galaxies in the Universe.

There is interaction of galaxies. We know this.

And sometimes they just capture stars.

It's a very large number of galaxies.

And behind that are some more modern galaxies.

There are billions of galaxies in the observable universe

There are billions of galaxies in the observable universe.

So they're moving further apart.

Distant galaxies were moving away from us.

How did the galaxies form? How did the planets form?

Subsequently many other observations have indicated the presence of dark matter in the universe, including gravitational lensing of background objects by galaxy clusters such as the Bullet Cluster, the temperature distribution of hot gas in galaxies and clusters of galaxies and, more recently, the pattern of anisotropies in the cosmic microwave background.

Galaxies form, and generations of stars form in those galaxies, and around one star, at least one star, is a habitable planet.

Galaxies, 100 billion of them estimated in the universe.

How are you going to put galaxies out there in a pattern like that?

Space itself is expanding at an accelerating pace.

And there are thousands of galaxies in this cluster.

Let us now turn to the shapes of elliptical galaxies.

That's what's blowing galaxies farther and farther apart.

The universe is mainly made out of dark matter overwhelming the stars, overwhelming the galaxies, in fact.

Some galaxies will see a temporary rebirth, if their mass gets stirred up and combined with another.

Galaxies spin, right? But they spin in all directions. If you add up all the spins of the galaxies what do you get?

Intergalactic space takes up most of the volume of the Universe, but even galaxies and star systems consist almost entirely of empty space.

Well what's pushing the galaxies apart is dark energy, the energy of nothing. Even vacuum has energy pushing the galaxies apart. And then what is the universe expanding into?

Now, there are a few relatively exotic galaxies.

And within these galaxies you get these enormous dust clouds.

look out, and you'll see the same galaxies as we do from here.

It's just one of billions of galaxies in the universe.

Formation of galaxies Large volumes of matter collapse to form a galaxy.

Knowing this, scientists looked at the galaxies and measured how fast stars were moving.

This dark matter can be envisioned as a cloud which surrounds most galaxies.

It is a perpetual impulse that pushes galaxies apart from each other.

In those galaxies, you'll be able to do astrophysics, and learn the laws of physics.

And the supermassive black holes are thought to reside at the center of galaxies.

Video Which in turn belongs to a local group of galaxies.

But one of the questions is this should be, to you how come there are so many galaxies?

In one of these gallasies, orbiting one of these stars,

But these galaxies are actually moving at extremely high speeds.