Why does the earth rotate?

[dad]

One site claims this

"
4.54 billion years ago, our Solar System formed within a cloud of hydrogen not unlike the Orion Nebula, or the Eagle Nebula, with its awesome pillars of creation.

Then, it took some kick, like from the shockwave from a nearby supernova, and this set a region of the cold gas falling inward through its mutual gravity. As it collapsed, the cloud began to spin.

But why?

It’s the conservation of angular momentum.

Think about the individual atoms in the cloud of hydrogen. Each particle has its own momentum as it drifts through the void. As these atoms glom onto one another with gravity, they need to average out their momentum. It might be possible to average out perfectly to zero, but it’s really really unlikely.

Which means, there will be some left over. Like a figure skater pulling in her arms to spin more rapidly, the collapsing proto-Solar System with its averaged out particle momentum began to spin faster and faster."
http://www.universetoday.com/14491/why-does-the-earth-rotate/


Some people apparently take this fable seriously and even call it science. Total 100% fable and story telling of course.

 

[Kylie]

Yeah, conservation of angular momentum is just a fairy tale...

 

[Goonie]

 

[FrumiousBandersnatch]

It's the same principle as seen when ice skaters pull their arms in while spinning so as to spin faster. Very basic physics.

What problem do you find with it?

 

[essentialsaltes]

Exactly, we all know the god of the bible created an immovable earth.

"Tremble before him, all the earth!
The world is firmly established; it cannot be moved."

 

[ecco]

The Orion Nebula and the Eagle nebula are comparable to our Galaxy, not to our Solar System.

Why does water rotate when going down a drain?

 

[essentialsaltes]

The Orion Nebula and the Eagle nebula are comparable to our Galaxy, not to our Solar System.

These nebulae are *in* our galaxy. Both feature active star-forming regions, and our solar system likely developed from a similar region in some other long-ago nebula or cloud of gas.

Why does water rotate when going down a drain?

Same as for the solar system description above. Angular momentum.

Think about the individual water molecules in the sink. Each has its own momentum as it moves about. As they pull into the center as the sink drains, they need to average out their momentum. It might be possible to average out perfectly to zero, but it’s really really unlikely. So the water swirls one way or the other.

(On a related note: It is untrue that the Coriolis force makes water swirl different directions in the Northern and Southern hemispheres. It is true that the Coriolis force makes hurricanes swirl different directions in the different hemispheres.)

 

[ananda]

It doesn't.

 

[keith99]

Yeah, conservation of angular momentum is just a fairy tale...

Once upon a time before we were scared to death that Johnny might skin his knee most playgrounds had hand push merry-go-rounds. Back then kids knew how to use the conservation of angular momentum and of course knew it was real.

 

[dad]

Yeah, conservation of angular momentum is just a fairy tale...

Yes, when applied to the tooth fairy smashing the earth with a giant toothbrush long ago, it is. You claim some wunderbar stardust smashed into the world in an imaginary past, and started it spinning!!!!! That is not possible to prove any more than the tooth fairy baloney. Why would anyone embrace such godless nonsense over creation as told by holy Scripture?

 

[dad]

Once upon a time before we were scared to death that Johnny might skin his knee most playgrounds had hand push merry-go-rounds. Back then kids knew how to use the conservation of angular momentum and of course knew it was real.

The kids never smashed into earth and made it rotate. The issue is not momentum in this present world. Nor the laws now.

 

[dad]

These nebulae are *in* our galaxy. Both feature active star-forming regions, and our solar system likely developed from a similar region in some other long-ago nebula or cloud of gas.

Sorry, this is not a thread to cite fairy tales as if they were truth.

 

[dad]

Exactly, we all know the god of the bible created an immovable earth.

"Tremble before him, all the earth!
The world is firmly established; it cannot be moved."

I wonder if you guys really misunderstand what you read, or are trying to be funny.

 

[dad]

It's the same principle as seen when ice skaters pull their arms in while spinning so as to spin faster. Very basic physics.

What problem do you find with it?

I do not believe basic physics applies to the universe outside of earth and solar system area. So forget trying to make a skater the illustration for galaxies. As for earth, They seem to be invoking some smash up derby that could never be proven as the real cause of rotation and spin..

 

[Loudmouth]

Once upon a time before we were scared to death that Johnny might skin his knee most playgrounds had hand push merry-go-rounds. Back then kids knew how to use the conservation of angular momentum and of course knew it was real.

Everybody step towards the middle on the count of 3!

 

[ecco]

These nebulae are *in* our galaxy. Both feature active star-forming regions, and our solar system likely developed from a similar region in some other long-ago nebula or cloud of gas.

Duh. My Bad.

Same as for the solar system description above. Angular momentum.

That was the point I was trying to make.

 

[crjmurray]

It doesn't.

It doesn't?

 

[ananda]

It doesn't?

I haven't personally seen or felt it rotate in all my lifetime. Feels pretty solid and stationary to me. Have you seen or felt otherwise yourself?

 

[Loudmouth]

I haven't personally seen or felt it rotate in all my lifetime. Feels pretty solid and stationary to me. Have you seen or felt otherwise yourself?

Yes. The Sun moving through the sky is a pretty obvious sign of the Earth rotating.

 

[crjmurray]

I haven't personally seen or felt it rotate in all my lifetime. Feels pretty solid and stationary to me. Have you seen or felt otherwise yourself?

I've never personally seen or felt a polar bear but that didn't stop my uncle from being eaten by one.

Now I'm genuinely asking here. You don't think that the earth rotates?