<p>It comes from angular momentum. Angular momentum is a conserved quantity of physics. That means that the sum of angular momentum of the universe is constant, even though some parts of the universe may transfer angular momentum to other parts.</p>

<p>We do not know the total amount of angular momentum of the universe, but from observations we know that it is not uniformly distributed. This explains why celestial objects rotate.</p>

<p>If the total amount of angular momentum of the universe would be zero it would be theoretically possible that rotation could cease in the future. However, nobody knows the ultimate fate of the universe, so this is purely speculative.</p>

CC BY-SA 3.0
2016-03-22T20:40:20.350Z
I think the date of the universe is total nothing and darkness... kinda sad :,( let's pretend it's a big crush with amazing light shows and Michaelbayly booms
Kyle
CC BY-SA 3.0
2016-03-19T19:45:43.307Z
2016-03-19T19:45:43.307Z
aventurin
<p><a href="https://www.youtube.com/user/minutephysics">The MinutePhysics channel</a> on YouTube made <a href="https://www.youtube.com/watch?v=tmNXKqeUtJM">a wonderful short animation</a> that answers your very question. It explains how a cloud of gas and dust with zero net angular momentum collapses down to form a flat spinning object such as a galaxy or our Solar System.</p>

<p>The answer involves a few things:</p>

<ol>
<li>The universe conserves angular momentum in every interaction between
physical objects.</li>
<li>Mathematics says a big cloud of gas and dust must have exactly one plane in which the overall angular momentum is zero.</li>
<li>When particles of gas and dust collide, any angular momentum they have outside that plane is cancelled, so over millions of years and (countless numbers of collisions) the cloud ends up flattening.</li>
<li>But as they collide, their angular momenta within that one plane are
conserved, so the flattened system ends up spinning.</li>
</ol>

CC BY-SA 3.0
2016-03-23T12:58:38.473Z
F yeah, I was waiting for someone to talk about that video, I've watched before :D, that happens even in a 2D universe
Kyle
CC BY-SA 3.0
2016-03-21T05:32:21.627Z
2016-03-21T05:32:21.627Z
RichS
<p>Almost all celestial objects are rotating in some way about their axes. Why is this and should we expect the rotation to slow as the universe ages?</p>

CC BY-SA 3.0
2016-03-18T12:10:27.100Z
Possible duplicate of [Why does a planet rotate and revolve?](http://astronomy.stackexchange.com/questions/387/why-does-a-planet-rotate-and-revolve)
ProfRob
CC BY-SA 3.0
2016-03-20T05:54:57.423Z
While in terms of content I can see why this is a sort of duplicate, the question isn't particular to planets (or anything else).
Warrick
<planet><rotation>
Why is the universe full of spinning objects?
Abhinav
# Why is the universe full of spinning objects?

(Asked by: username_0 on 2016-03-18)

Almost all celestial objects are rotating in some way about their axes. Why is this and should we expect the rotation to slow as the universe ages?

**Tags:** planet, rotation
> **Comments:**
> **username_1**: Possible duplicate of [Why does a planet rotate and revolve?](http://astronomy.stackexchange.com/questions/387/why-does-a-planet-rotate-and-revolve)  
> **username_2**: While in terms of content I can see why this is a sort of duplicate, the question isn't particular to planets (or anything else).  

---

## 2 answers

### Answer by username_3 on 2016-03-19. Score: 4 | Accepted answer

It comes from angular momentum. Angular momentum is a conserved quantity of physics. That means that the sum of angular momentum of the universe is constant, even though some parts of the universe may transfer angular momentum to other parts.

We do not know the total amount of angular momentum of the universe, but from observations we know that it is not uniformly distributed. This explains why celestial objects rotate.

If the total amount of angular momentum of the universe would be zero it would be theoretically possible that rotation could cease in the future. However, nobody knows the ultimate fate of the universe, so this is purely speculative.

> **Comments:**
> **username_4**: I think the date of the universe is total nothing and darkness... kinda sad :,( let's pretend it's a big crush with amazing light shows and Michaelbayly booms  

---

### Answer by username_5 on 2016-03-21. Score: 7

[The MinutePhysics channel](https://www.youtube.com/user/minutephysics) on YouTube made [a wonderful short animation](https://www.youtube.com/watch?v=tmNXKqeUtJM) that answers your very question. It explains how a cloud of gas and dust with zero net angular momentum collapses down to form a flat spinning object such as a galaxy or our Solar System.

The answer involves a few things:

1. The universe conserves angular momentum in every interaction between
   physical objects.
2. Mathematics says a big cloud of gas and dust must have exactly one plane in which the overall angular momentum is zero.
3. When particles of gas and dust collide, any angular momentum they have outside that plane is cancelled, so over millions of years and (countless numbers of collisions) the cloud ends up flattening.
4. But as they collide, their angular momenta within that one plane are
   conserved, so the flattened system ends up spinning.

> **Comments:**
> **username_4**: F yeah, I was waiting for someone to talk about that video, I've watched before :D, that happens even in a 2D universe  

---

