[Truth or Fiction]

I'm new here, but, this is where my head is:

If the Earth is spinning perpetually due to the void/vacuum offering no resistance to the spin and there is no force currently acting upon it to spin, how is it that introducing another axis of spin does NOT cause complete chaos?

I understand that the imaginary poles that people envision are just that; imaginings and should play no role in our investigations.  Therefore, when another axis of spin is introduced (again, within a vacuum and nothing to stop it), how does it just loop around causing the seasons on this N/S shift?

I'd like to see a supercomputer figure this out for me... because, in reality, I cannot make it happen.  Using levitation 'balls' one can get a spin on it, but, the introduction of the second is impossible as far as I can determine without catastrophic failure upon earth

How is this possible?

[AATW]

how is it that introducing another axis of spin does NOT cause complete chaos?

What other axis of spin?

[BillO]

What other axis of spin?

I think he thinks that it's path around the sun means there is another axis of spin.

That's not the case.  At least not in RE science.  In RE science the earth is in orbit around the sun.  From a GR perspective it's just falling through it's local space.  There is no "spin" axis evolved. 

[Truth or Fiction]

What other axis of spin?

I think he thinks that it's path around the sun means there is another axis of spin.

That's not the case.  At least not in RE science.  In RE science the earth is in orbit around the sun.  From a GR perspective it's just falling through it's local space.  There is no "spin" axis evolved.

Thanks... for the reply.  I was just creatively thinking.  It was from trying to figure out how this was possible in a void.  If you are hit and rotate, what will stop you from continuing?   It's truly hard for me to read anything from NASA and take them seriously.   From NASA.

"But what caused Earth to tilt?
Cartoon of large object hitting Earth, knocking out big chunks of material that become the future Moon, and tilting the Earth's axis.    lol


Long, long ago, when Earth was young, it is thought that something big hit Earth and knocked it off-kilter. So instead of rotating with its axis straight up and down, it leans over a bit.

By the way, that big thing that hit Earth is called Theia. It also blasted a big hole in the surface. That big hit sent a huge amount of dust and rubble into orbit. Most scientists think that that rubble, in time, became our Moon.

As Earth orbits the Sun, its tilted axis always points in the same direction. So, throughout the year, different parts of Earth get the Sun’s direct rays..."

[BillO]

"But what caused Earth to tilt?
Cartoon of large object hitting Earth, knocking out big chunks of material that become the future Moon, and tilting the Earth's axis.    lol

Why do you find this so unbelievable?

[Truth or Fiction]

"But what caused Earth to tilt?
Cartoon of large object hitting Earth, knocking out big chunks of material that become the future Moon, and tilting the Earth's axis.    lol

Why do you find this so unbelievable?

Because, in a vacuum, void, etc., which is supposedly where the earth resides, it's ONLY because it's a vacuum with no resistance that the perpetual motion of earth continues.  I might be incorrect in my understanding of that, but, let's continue.

If Earth were spinning, and had a certain alignment with the Sun, I find it hard that a collision that knocks it hard enough to cause it to move 23.5 degrees (mind you, that movement must have some 'imaginary' axis through the earth, right?) is not going to do more than that.  It's as if a spin were initiated and then halted somehow.  I'm not buying the 'somehow', nor am I buying that the collision that large would not have sent the earth off it's current trajectory--before the collision.

Spin a globe in a vacuum and then add a collision to knock it off kilter, and if it does what earth does, I'll be satisfied, I imagine.  Only, it can't be CG.   Another thought is this:  There is no pole in which the earth revolves around  that would help 'balance' it or revolve around; this event would cause chaos to any rotation and alignment as far as I believe.  We tend to forget, when we imagine, it as being just a globe randomly spinning NOT on any 'pole' that exists in reality.

That's my issue.  A force caused something to happen, then no force stopped it.

[Iceman]

I think that what you’re saying would be true for a homogenous object with regular dimensions and even mass distribution with no other external forces acting on it.

But the earth ain’t those things.

[Jonathan]

I'm new here, but, this is where my head is:

If the Earth is spinning perpetually due to the void/vacuum offering no resistance to the spin and there is no force currently acting upon it to spin, how is it that introducing another axis of spin does NOT cause complete chaos?

[stack]

What's up with the video? I'm not gonna watch a 30 minute YT about what looks like some steampunk gyro without some context. I doubt anyone else will either. Cool looking though.

[SteelyBob]

"But what caused Earth to tilt?
Cartoon of large object hitting Earth, knocking out big chunks of material that become the future Moon, and tilting the Earth's axis.    lol

Why do you find this so unbelievable?

Because, in a vacuum, void, etc., which is supposedly where the earth resides, it's ONLY because it's a vacuum with no resistance that the perpetual motion of earth continues.  I might be incorrect in my understanding of that, but, let's continue.

If Earth were spinning, and had a certain alignment with the Sun, I find it hard that a collision that knocks it hard enough to cause it to move 23.5 degrees (mind you, that movement must have some 'imaginary' axis through the earth, right?) is not going to do more than that.  It's as if a spin were initiated and then halted somehow.  I'm not buying the 'somehow', nor am I buying that the collision that large would not have sent the earth off it's current trajectory--before the collision.

Spin a globe in a vacuum and then add a collision to knock it off kilter, and if it does what earth does, I'll be satisfied, I imagine.  Only, it can't be CG.   Another thought is this:  There is no pole in which the earth revolves around  that would help 'balance' it or revolve around; this event would cause chaos to any rotation and alignment as far as I believe.  We tend to forget, when we imagine, it as being just a globe randomly spinning NOT on any 'pole' that exists in reality.

That's my issue.  A force caused something to happen, then no force stopped it.

I think I see what your confusion is. You’re absolutely right: F=MA, which means bodies have constant velocity unless some net force acts upon them causing an acceleration. For things flying in our atmosphere, or for things being pushed along the ground, that usually means that friction or air resistance will decelerate an object to an eventual standstill unless we add some energy via an engine etc.

In space, with essentially zero air resistance, things will just keep on flying at whatever velocity they happen to be at. The only forces acting on bodies in space are gravitational ones. A really cool example of this is the Apollo 12 third stage - due to a mistake in its control system, it missed its intended endgame orbit and is now still merrily and very chaotically flying around the solar system.

https://en.m.wikipedia.org/wiki/J002E3

So you are quite reasonably asking why, if the earth took a knock, isn’t it still just endlessly rotating from that initial impulse?

Great question. The answer lies in the confusing and not at all intuitive world of rotating bodies. Had the earth not been rotating when it was hit, that is exactly what would have happened. However, it was already rotating. This means it was essentially a massive gyroscope. F=MA still applies, but you have to consider that every component part of the earth is already accelerating, centripetally, prior to the impact. This means that the rotating body does not behave as you would expect it to. For a start, if you impart a force on something spinning, it won’t move the way you think it will - it will ‘precess’, moving in a way that appears as if you you actually imparted a force 90 degrees further around in the direction of rotation. You can prove this yourself with a spinning bike wheel. The other oddity is that when the force is removed, the precession will immediately stop, which isn’t what we expect from our normal experiences. This is exactly what happened with the earth. The impact caused it to precess, tilting its rotation axis.

https://youtu.be/ty9QSiVC2g0