I have a question. If for some reason Earth stopped rotating, would it start up again on its own? My one friend and I are having an argument on this.

I think that it will start rotating again. I have no scientific fact to base this on, but you would think it would, otherwise no planets in the universe would spin. My friend does not see how it could start spinning again.

Any REAL scientific fact behind this would help. Links will also help. Oh, and before I start cooking with flames, I want you to know that I DID look online first.

I think it would because of gravitational forces acting upon it (the Sun, the Moon and the planets). But it would be a very slow startup and we'd probably all be dead before it happened. (Killed off from the havoc wrecked by a stopping Earth.)

BINGO! That is what I thought to. Oh btw, according to the Zetan alien race, the earth will stop rotating this May!

Nope, they are wrong, we are not scheduled to be enslaved until 2012 or 2015, I have to check my project schedule, they keep changing the date.

You'd fall off. x(

So if the earth stopped spinning... it would also lose any gravitational pull it had and you'd float off into space? FAIR ENOUGH!

>So if the earth stopped spinning... it would also lose any
>gravitational pull it had and you'd float off into space?
>FAIR ENOUGH!


No, it would still have mass and therefore gravitational pull.

Jim.

Hence my sarcasm. Oh well

Interesting hypothesis. With no centrifugal force to counter that of gravitational forces would we all be squished like bugs?

Or is Gravitational force actually of function of magnetism caused by the Earth's rotation and would the gravitational forces also be decreased as the Earth slowed. Hmmmmm......

Glad to see you off and running again.

Bob

Sonny, corner the Velcro market! That'll keep everybody stuck! :+

check this site out

http://itss.raytheon.com/cafe/qadir/q1168.html

Google search
'what if the earth stopped rotating'

you'll learn more than you ever wanted to know.

Hmmm... that does not bode well...

But would it start up? I know that if the earth stopped, well, we'd all be screwed, but would it start up again? I hope so, because I can't lose this debate!

well i definitely can't answer your question with any facts, but my theory would be that if the earth stopped rotating, it would either be because the sun or the moon was no longer in position to pull it. So if there isn't more than one force pulling on the earth, I don't think it would start rotating again until there was more than one force.

but I have no idea for certain.

I say that it would start up again, but not with same rotation on the same axis as before. The globe is still rotating around the Sum, which has the greatest garvitation pull on it. The ball isn't perfectly round, so it would eventually start to wobble until a spin starts up.

What's to say that the rotation of the Earth won't speed up?

Wow. Quite interesting. So you'd either get killed in the scouring, the temperature changes, or the massive radiation increase. Not a very good array of choices.

Now that I think about it, we're all travelling at Earth's 1100 mile per hour rotational speed. Think about what happens if you're not wearing a seatbelt when your car crashes and goes from 60 to 0 instantly. Every person on the Earth would continue going at 1100 mph in the direction they happened to be headed (with Earth's rotation) at the time. So we'd (and everything not nailed down, plus some things that are) go flying in the air. Not sure if we'd reach orbit, but either way it would get very messy.

yep thats just what i read in that link. we'd all be quite screwed :P if it stopped suddenly, but if it slowed to a stop, we may have a chance, but we'd have to overcome the crazy climate changes first.

Yeah, messy indeed. But that speed is only if we are at the equator. It would be like getting hit by an atomic bomb

you might get more info at a physics website dealing with astro-physics, or what ever it is called. some less advanced, or less specific, physics websites might also be able to provide more info.

if the earth stopped spinning, then i do not think anyone would live long enough to be able to tell you whether it would start spinning, again, so you are dealing with fantastical theory, nothing testable. nonetheless, if the planet stopped spinning or rotating around the sun, or both, then there would probably also be such a universal change to the cosmos that laws of physics might entirely change, too. if that was the case, then we could not guess what would happen. if the earth stopped spinning, or rotating around the sun, then extreme changes would probably also occur for other planets and cosmos items, too. i do not see why only the earth would be affected, if such an extreme change happened to this planet.

you would, or should find a nice pub atmosphere and a few healthy brewskies a more interesting, as well as healthier (yes, good brew is healthy) and more practical environment and subject, though. another subject weighing on my mind is how to get a farm and start some interesting organic farming. now, there are a couple of subjects which interest me; and, i can see the interest remaining until i am unable to think anymore.

mike

p.s. the laws of physics are not going to change that much, not in our lifetimes anyway. go for a brew.

Well... I don't know THAT much about physics, but I THINK that a lot of what you said is wrong. You are saying that if the earth stopped rotating, all of the laws of physics would change? Ehh... no

What if a MASSIVE asteroid came close to earth, but did not hit. THe mass of the asteroid was enough to stop the earths rotation? Maybe.

But let's say we are struck by a massive meteor, that caused the earths rotation to SLOW, not just STOP. Would only HALF of the laws of physics be changed?

An article that may answer your question is at:

www.bonus.com/beakman/worldturn/worldturn.html

Bad link? Or is it me?

nope didn't open here either.

This page is a popup window loaded from another page, so if you are using some sort of Popup stopper, it may prevent you from seeing it.

Nope, no popup killer.

Not Found
--- The requested object does not exist on this server. The link you followed is either outdated, inaccurate, or the server has been instructed not to let you have it.

Worked for me just fine. Very interest and funny look at this debate. Thanks Dubber.

Crazy :7

hypothetical. The Evil Lex Luthor turns himself into Cosmo Man , grabs the Earth and stops it spinning on it's axis( but not rotating about the sun ). Everybody and every thing on earth dies. That is a given.

Now bored...Cosmo Man goes off to other parts of the Universe to wreak havoc.

The Earth still rotating around the sun will start to spin again. It may take Billions of years, but the gravitational drag acting on the surface of the Earth will start it rotating again. Same principle as a DC motor where opposing\attracting magnetic forces cause the armature to rotate. Magnetism and Gravitational forces are very closely interlinked and quite similiar in their reaction on physical objects. At least that's what I can remember from some of my Grade 11 and 12 Science and Physics courses.....so long ago.....

Edit: Spelling.... still don't know how to spell Brewskee's though. :D

How could the gravitational pull of a passing object stop the spin of the globe? If you drop a spinning ball on the floor it'll still spin until friction stops it, not gravity.

If the gravitational pull of a passing object is so powerful as to affect rotation, then I'm sure that the globe would wind up being towed by it - if it doesn't shatter from the strain first.

Funny you should mention that, "getting struck by a meteor". Just such an event happened to me last summer on my annual trek to Area 51 to join the "others".

In my eagerness to start the trip I forgot my helmet and had to buy another one in the local grocery. I also had to find a grounding chain at the hardware store down the street and all they had was a fifty pound welded link towing chain which I had to drag around behind me.

They didn't want me on the Greyhound wearing all my protective gear and the only way to that famous little town in Texas where the aliens had been seen, I was struck on the head before I got my helmet in place when leaving the bus. A meteor swarm was falling everywhere down there, they even named the place "Caution, Falling Rock".

I saw the sign alongside the highway as the bus drove around through the hills and cliffs just outside town......

hope i'm wrong for your sake denki, but i definitely don't think it would start again if it was completely stopped.

The gist of the article is that the moon hitting the earth is what started it spinning. Otherwise it would not be spinning or would spin very slowly. So, if it stopped spinning, something else would have to start it, like the moon hitting again, which is not very likely.


Here's a screenshot of the site(It's a little rough looking because I limited it to 14 colors to get the file size under 50kb):

Well, then how does Venus spin? Mars? Jupiter? And so forth? Did moons hit them too?

its the force of the sun and the moon pulling on the earth at the same time that makes the earth rotate. Mars, Jupitor, Venus, all have moons.

edit: i take that back, venus does not have a moon, but its rotation is incredibly slow, 243 days to make make one rotation

Another possiblity is that the material that formed the planets was spinning during the formation and retained that spin afterwards, which also would not be able to be duplicated a second time.

If one subscribes to the big bang theory of universal birth it evolved from a single spinning mass of gases dust matter and unknown energys spinning in nothingness of space, exploding and sending parts of itself spinning off into space and further spinning off parts of these spinning parts to form the galaxys solar systems and planents and moons all spinning in relation to each other in space a vacume.
For argument we accept this premiss in which case each will continue to spin UNLESS some ouside force acts upon it to stop its spinning, as there is no friction in a vacume to degrade the inertia of the spinning object. Now lets say this ouside force happens whether asteroid meteor or big hand reaching out and grabbing this blue ball called earth once stoped it will remain stopped until some other outside force acts upon it to begin spinning again. I am no scientist or physicisist but my proof is actual and seeable.
Old son you have lost your bet, look up in the night sky at the moon one of the few non rotateing objects in the universe. Even though it has recently been discovered that it does have microscopic rotation it is measured in mm per yrs the eaxact figures i dont remember.

So in essence is it a microscopic beginnig of rotation or the last traces of its lost rotation who knows.
dannyboy

I lost. ::sigh:: I hate losing arguements! Especially since the kid I was argueing with was SWEDISH! ahhhhh! I'll never hear the end of it! Thanks guys!

This is a very complex thing. If you take in account that Earth is not a 100% solid planet (The planet core and most of its mass is liquid) you will have to conclude that different parts of the core of the planet would be facing the Sun as the Earth goes around its orbit.
The gravitational forces of the Sun over those parts would be stronger than the forces over the distant ones, eventually the core of the planet would start rotating and this rotation could be transmitted to the solid-external part of the planet, it would take a long time, but eventually the Earth will start rotating.
Another consideration is the Moon, you didn't talk about the Moon, but if the Moon is still there and rotating around Earth, it will make the Earth start rotating and as before it will take a long time.
By the way the tendency is that the Earth's rotation is slowing down, influenced by the Moon rotation (Rotates every 28 days) the solar wind, the small friction of the intergalactic space and the relentless but slow process of the Earth falling into the Sun (around 2 inches a year or so), but don't be afraid it will take billions of years before we get there and probably our Sun will run out of fuel before that.

I learned the most important bit of knowledge that we must take into consideration when persuing such a weighty subject.It was written (by an alien most likely) on the wall over the urinal in a bar in Boulder,Colorado in 1974:
"GRAVITY EXISTS BECAUSE THE EARTH SUCKS"}>

I dont think that it would be possible for the earth to fully come to a complete stop with the moon so close and the sun...the gravitational forces would always be pulling on it in some way. But if It did fully stop by some force I think it would definately start to spin in some way to some degree, unless it gets knocked out of the orbit of the sun and moon and then is stopped. With the effects of enertia...just about everything is space is going to move and once its moving it will keep moving. I think space itself is always exspanding so everything is moving outward a little bit even if it appears to be sitting still. Thats my theory anyway. Everything is in motion at all times. From what is know or at least in theory space is exspanding but the rate at which it exspands is slowing down. SOme theorize that if it continues to slow down that eventually it will stop and then start to contract back upon itself. If that is true then there should be a brief moment when the Universe stops expanding..comes to brief hault before it starts to contract. So at that brief moment that should be the only real time when anything could be perfectly still(not moving or spinning at all). A similar effect that would happen when you throw a ball up in the air...it moves up and gravity pulls against it then for a brief moment it hangs then starts to decline. Anyway Im no physics expert but this is just my thoery. And its not much of a theory at that. haha
Garbru

a brief moment when the Universe stops expanding..comes to brief hault before it starts to contract. So at that brief moment that should be the only real time when anything could be perfectly still(not moving or spinning at all).

That's a funky theory if ever there was one.

A similar effect that would happen when you throw a ball up in the air...

No it doesn't the relative movement of the ball with respect to the ground stops, but the ball is still spinning, and the atoms and electrons in the ball are still moving.

You may be right about the ball... but as far as the universe goes it could be a bit different. I believe that the time and space are relevant...which means that if the universe would change directions(contract instead of exspand) would that mean that time would change directions too? If that is so then for a brief moment before the contraction starts there should be a point at which time stops. And if time stops then nothing can move. I guess einstien mathematically proved that time would reverse if the earth stoped and began to spin in the opposite direction. Its just a theory but something that we cant really test withought superman.


Garbru

Einstein never predicted that and nobody thatI know has ever tried to prove that mathematically, the small angular velocity of the Earth (if you compare it to the speed of light) would not have any meaningless effect on time.
You are assuming that all the objects in the universe (Galaxies, clusters, intergalactic matter etc.) would stop at the same time and reverse course, that is not true either, the general trend at one point would be that the Universe start contracting, but not all objets in the universe would start doing that at the same time, larger objects with more inertia would start later (much later) than smaller objects at the center of the Universe and even some objets within a Galaxy that has already reversed course, will continue moving in the original direction if they have more inertia than the vast majority of the stars that make up that Galaxy. Eventually those objects will reverse course but at a later time.

Under no circumstances will the direction of time reverse. Stephen Hawking is arguably the finest mind in theoretical physics alive today. The following is part of a lecture he delivered that touches upon this subject:

Originally, I thought that the collapse, would be the time reverse of the expansion. This would have meant that the arrow of time would have pointed the other way in the contracting phase. People would have gotten younger, as the universe got smaller. Eventually, they would have disappeared back into the womb.

However, I now realise I was wrong, as these solutions show. The collapse is not the time reverse of the expansion. The expansion will start with an inflationary phase, but the collapse will not in general end with an anti inflationary phase. Moreover, the small departures from uniform density will continue to grow in the contracting phase. The universe will get more and more lumpy and irregular, as it gets smaller, and disorder will increase. This means that the arrow of time will not reverse. People will continue to get older, even after the universe has begun to contract. So it is no good waiting until the universe re-collapses, to return to your youth. You would be a bit past it, anyway, by then.

The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down. Nevertheless, the way the universe began would have been determined by the laws of physics, if the universe satisfied the no boundary condition. This says that in the imaginary time direction, space-time is finite in extent, but doesn't have any boundary or edge. The predictions of the no boundary proposal seem to agree with observation. The no boundary hypothesis also predicts that the universe will eventually collapse again. However, the contracting phase, will not have the opposite arrow of time, to the expanding phase. So we will keep on getting older, and we won't return to our youth. Because time is not going to go backwards, I think I better stop now.

I would recommend reading the entire lecture. It is in simple language, and full of Hawking's characteristic humor. It may be found at:

http://www.hawking.org.uk/lectures/bot.html

Its all very weird. We have to try to figure out how the universe is and what is actually going on with it and the truth is that we will probably never really know, and I dont think that we are ment to know. Part of the difficulty is perspective. We have to figure out the structure of the universe or how it functions from our place in it and that is difficult. If we had the ability to move around the galazies more we would be able to have a better look at it but its impossible. Who knows what is really out there. Some say that space is never ending and some thoerize that space warps back around itself so that it has neither a begining nor an end....whic means at any point were you are in it it almost appears as if you are in the middle of it. At least Ive read some things about that.....but WHEWW you can really rack your brain on this stuff. There has to be a certain size of it...meaning it cannot go on forever in any direction....the fact that things like Hallies comet comming back every several decades or so tells me that space must be a fixed size and most likely curved somehow or who knows I dont know anything. Im gonna need a drink after this thread.


Garbru

I get a kick out of your posts about this business. First, Haley's comet, like all comets are in orbit around the sun, just like the planets, they will come back unless their matter is dissipated by the sun or they collide with something.

Second there is nothing, that is not ultimately knowable in the universe. There is nothing we are not intended to know.

I really suggest you read the entire lecture I provided the link to. Supposition not based upon reality as a waste of intellect.

The fact Haleys comet repeated appears is;
IT IS CAPTURED IN THIS SOLAR SYSTEM

ALSO ASTRONOMERS TELL US OTHER CONSTELLATIONS ARE EXPANDING
MOSTLY AWAY FROM US

AND NOBODY HAS EVER FOUND THE LIMITS OF THE UNIVERSE

You have stumbled into a very complex concept. I will now proceed to make you regret it.

The simple answer to your question is no. If the rotation of the earth somehow stopped, it could not resume its rotation without the aplication od a truly huge applied external force. But for the same reason, the rotation of the earth will not stop.

The reason is a law of physics known as the Conservation of Angular Momentum, which was described in Newton's laws of motion, and Kepler's laws of planetary motion.

Simply stated the rotational velocity of an object will remain constant unless acted upon by an outside force, and an object not rotating will remain stationary unless acted upon by an external force. You may recognize this as being the same as Newton's first, and second laws of linear motion. They are based upon the same concepts.

If you remember his third law, an action has an equal and opposite reaction, that comes into play with angular momentum also. The total rotational velocity of a system must remain constant, rotational momentum can not be gained or lost within a system. If the earth were to slow down that momentum would be transferred to another object, in this case primarily the sun.

An interesting example of this is that everytime a space ship leaves the earth, it gains momentum from the earths rotational velocity, and the earth slows down a tiny bit as a result, when that ship returns to earth and lands, that velocity is returned to the planet and the earths rotation speeds up by the same amount it slowed down.

An example of the conservation of angular momentum is offered by our earth. The earth rotates about an axis going from the south to the north pole. The main force acting on the earth is the force of gravity from the sun. Because this force acts on the center of mass of the earth it does not produce any torque with respect to the axis of rotation and so the angular momentum cannot change. This is what gives us a day of constant average length since prehistoric times.

By the way, contrary to what was stated in another post, magnetism and gravity are two completely separate things. Gravity is a function of mass, so if the earth did stop rotating, we would lose our magnetic field, but the earth's gravity would remain the same.

OUTSTANDING, SHELLY !!!

You have, again, taught me a thing, or two, about the world we live in. How many advanced degrees in physics do you hold? Damn, you're good!

Shelly... I see your name, and the following happens.

1. I place my hand on my forehead
2. I sigh
3. I the say "jesus christ"
4. I proceed to see you flame, cut, slice, and puncture anything I say.
5. Then I say, "Thank you Shelly."


Thank you Shelly. You once again shattered my self-esteme by endulging me in your wisdom.

Actually Shelly is wrong and the Earth, even now as we speak has begun slowing down because of the friction of the air. When we first started the Earth was just a round smooth ball with no measurable surface structure to cause air movement or friction but as mankind began building structures and mountains and things we started rubbing against the molculars of the air, you know, disturbing the clouds and stuff.
Soon we will be at a standstill and all the water will float up into the sky, there won't be any grabity and I can soon be swimming into the bottom of the ocean up there.......

Actually you are right but not for that reason, Earth rotation has been slowing down for billions of years at a rate of 0.001 sec a century and that's not a theory as it has been messured. The main reasons is the attraction of the Moon, the Solar wind and the intergalactic matter.

I had a friend once that was afflicted with intergalactic matter. They had to go in and scrape it every once in a while. I've been accused of passing wind too but Solar wind sounds like a lot of hot air......

Old Dude, what medications are you on?? Id like to try some!
send any extra pills to my house.

Garbru

Shelly has been prescribing for me. It's some stuff from a warehouse down in Juarez, I think he knows some dude down there.

And Roni, if you were able to gain any sensible information from my post above then I think you're just trying to be a nice person.....
I can't really swim upside down.....

Hey, at least I didn't include all the math I had jotted down. It's just too much work with the forum script and the Greek letters...

Y'know Shelly, we could apply the laws of physics and actually get the globe to stop spinning by getting everybody to run East, against the rotation. We'll eventually slow it down and cause the Sun to rise in the West! :+

Thus the westering instinct in all mankind

If the earth stopped spinning, we wouldn't be able to see if it starts up or not...we'll be in space.

Yeah, but I heard that Russia wants to blow up the moon, then what?

Why does everyone keep on saying that? Am I missing a BIG concept here? I was always under the impression that we were stuck on this planet here because EARTH'S gravity was PULLING on us, because Earth has MASS. Now if we stopped spinning, earth would not lose its mass.

Correct? Or am I missing something very important?

You are correct, Denki. I thought I had made that clear. There are however other consequences. An earth without spin would be subject to huge storms that would shred the atmosphere due to the tremendous temperature differences created. The oceans also would either freeze or boil. All life would be destroyed.

But many things could cause such catastrophe. The conditions needed to support any kind of life we can imagine are very specific, and very fragile.

My mistake...having a stupid attack.

Shelly, does this mean that if an "infinite" number of space ships leave the earth, would its angular momentum decrease toward zero?

Dan\'l

Here's a link to some info on gravity.
http://spaceprojects.arc.nasa.gov/Space_Projects/SSBRP/gravity.html

JD

Yes, but first you need to come up with an "infinite" number of space ships.

Next experiment: what if we dig a tunnel all the way through the Earth (ignoring the complication of magma), and jump in?





Zema Bus

You would bob up and down for a while, and come to rest at the center of the earth.

I think that would be by the the coolest thing anyone could ever do. It would be like a bungee jump, but without the cord.

I want to try!

Well start digging!

Actually that arguement is based on the slingshot effect used to add impetus to the launch. As fuel and rocktry engineering improve we can expect rockets to take off directly from their launchpad without borrowing anything from the earth's energy.

I'll tell what I think....

Shelly has been an avid reader, has an incredibly retentive mind, an ability to assimilate and understand the world around him. An extremely curious individual, never accepting a stated axiom without his own proof.
He comes from a strength of actually knowing what he's talking about and not just what someone has written with the appropriate letters behind the name.

I don't think any of us have seen more than a dribble of Shelly's intelligience....


All that and I don't even like the guy.... :P :P :D :D }>

(snip)
An example of the conservation of angular momentum is offered by our earth. The earth rotates about an axis going from the south to the north pole. The main force acting on the earth is the force of gravity from the sun. Because this force acts on the center of mass of the earth it does not produce any torque with respect to the axis of rotation and so the angular momentum cannot change. This is what gives us a day of constant average length since prehistoric times.

Hmmm.... I think I may have to disagree. Gravitational forces do not act solely on the center of mass of the earth...it acts on the whole mass. The surface of the Earth facing the sun would have a greater force acting upon it due to it's closer proximity to the gravitational force. The surface opposite the sun would have a lessor gravitational effect acting upon it.

Assuming that the Earth had stopped, including it's liquid core, would not this induce a torque moment on the planet enough to start it spinning again? Might take several Billions of years though.


OH C**P!!! Never mind....I think I've got it. Synchronous orbit. No torque moment because no change in position realtive to gravitational force. Nuts!!! Shelly's right again.....I think ;-) .

All I'm sure of is that my brain hurts :)

This is a very interesting question and the answer isn't as obvious as you may think. Here's an experiment to try in your kitchen:

* (carefully) spin a fresh egg on the kitchen counter
* while it is spinning, press a finger gently on it until it stops
* once stopped, quickly release it
* what happens?

Now repeat with a hard-boiled egg (or some other solid ball-like object).

You should have noticed the egg in the first part start spinning again. This is because it has a liquid centre which continues to move even through the solid shell is at rest, once released, this moving core causes the whole egg to start spinning again. This is all related to inertia and conservation of angular momentum as mentioned by Shelley in another post.

Obviously without stopping the Earth to see, I can't say this will happen, but as the Earth is a solid shell with a liquid core it is a possibility, so I guess that assuming the forces that stop it spinning are short lived then it could start moving again 'all by itself'.

Richard
www.richmac.org

Jumping way back to the reference to the "Raytheon" Link, I read thru it and was puzzled by this statement:

"If the rotation period slowed to 1 rotation every 365 days a condition called 'sun synchronous', every spot in the Earth would have permanent daytime or nighttime all year long. This is similar to the situation on the Moon where for 2 weeks the FRONT-SIDE is illuminated by the Sun, and for 2 weeks the BACK SIDE is illuminated." (caps are mine)

I don't think that this is at all correct...could Pink Floyd be wrong???

This is why you can't blindly use the net for research...a post is not a proof.

Win

Think about it. The moon is synchronized with the earth, and therefore presents all sides to the sun in the course of its 28 day orbit of the earth. If the earth were synchronized with the sun, the same side would always be pointing toward the sun.