The proof of earth's non-motion: the experiments

[Silvertiger]

That's not orbit. An orbit requires that at least two objects rotate about a common center of mass, which is empty space if the masses are comparable. Since the earth lies AT the COM of the universe, then it orbits nothing, and the sun doesn't orbit the earth.

[Fletcher]

Orbit :

noun: orbit; plural noun: orbits

1. the curved path of a celestial object or spacecraft round a star, planet, or moon, especially a periodic elliptical revolution.

"the Earth's orbit around the sun"

verb: (of a celestial object or spacecraft) move in orbit round (a star or planet).

"Mercury orbits the Sun"

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Gravitational slingshot maneuver : Gravity Assist : Inelastic collision.

http://hyperphysics.phy-astr.gsu.edu/hbase/doubal.html

Scroll down.

[ovyyus]

In an infinite universe would everywhere be the centre?

[Silvertiger]

I suppose this is a worthwhile digression LOL.

Orbit :

noun: orbit; plural noun: orbits

1. the curved path of a celestial object or spacecraft round a star, planet, or moon, especially a periodic elliptical revolution.

"the Earth's orbit around the sun"

verb: (of a celestial object or spacecraft) move in orbit round (a star or planet).

"Mercury orbits the Sun"

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Gravitational slingshot maneuver : Gravity Assist : Inelastic collision.

http://hyperphysics.phy-astr.gsu.edu/hbase/doubal.html

Scroll down.

That's great for a layman's definition. But remember that Newton's law of universal gravitation must fit in there somewhere. Something about...two or more bodies corotating about a COM, aka "barycenter"?

Once again...at least two masses must be involved in an orbit. The other requirement that comes from that is that they must be gravitationally tethered to each other in order for it to BE considered an orbit, otherwise it is not an orbit. If an object lies at the center of mass where all forces cancel such as gravity and torque, then there is no orbit. In fact, you can remove the earth from its spot in space, and the motion of the sun and its planets will not be affected by this change, whereas if the earth were orbiting the sun and suddenly disappeared, the sun's motion and the motion of its planets would change.

Animation of an orbit

Consider the following scenario: If you were to remove all celestial bodies except the sun and the earth, then the sun and the earth would begin orbiting each other about a barycenter somewhere inside the sun, but not its center. Now, duplicate the sun so that you have two suns, as in a binary system, that are orbiting each other about a barycenter halfway between them. That spot is empty space. Now, place a golf ball right there. Are the two suns said to be orbiting the golf ball? Of course not!

But WHY?

This is physics 101. An orbit is caused by gravity. It is nothing more than projectile motion, and the math is the same. You throw a ball straight, and it wants to go straight, but gravity brings it down. If you make the ball go fast enough to where its tangential velocity matches the acceleration of gravity, then presto, you have an orbit!

Thus, without gravity...there can BE no orbit. Not sure if I can it explain it much plainer than that LOL.

In other words, I could put a human being in the barycenter of two stars orbiting each other, and that person would not be affected by their gravity.

[daanopperman]

Hi S/T

You claim that the Foucault's pendulum swing is effected by the rest of the universe spinning around the Earth , should it not also effect the Earth , please explain why .

[Silvertiger]

It's because there is zero net torque acting on the earth, since the earth's COM is also at the COM of the universe. For anything ON the surface that has free range of motion however, whereby any low friction coefficient is practically negated due to the earth's shear mass, there IS a net torque applied, such as on the atmosphere, water in a toilet, and on the Foucault pendulum.

[daanopperman]

Hi S/T ,

The Cassini spacecraft used gravitational slingshot on it's journey to Saturn , it slingshot Venus 2 times , Earth once and Jupiter once on it's way .

If Earth was stationary there could not have been a energy exchange between the 2 .

If I place the Foucault pendulum 6300km under the surface of the earth do you think the pendulum will still begave as it does on the surface .

[Silvertiger]

...Earth once...

Whether the earth is static or not, a slingshot maneuver can still be performed...since it has gravity. Gravity doesn't care if you're spinning or not; it won't go away if you aren't.

If I place the Foucault pendulum 6300km under the surface of the earth do you think the pendulum will still begave as it does on the surface .

Nope...but you already knew that.

[eccentrically1]

Whether the earth is static or not, a slingshot maneuver can still be performed...since it has gravity. Gravity doesn't care if you're spinning or not; it won't go away if you aren't.

This is a common misconception. The assist doesn’t come from gravity, it comes from the motion of the orbiting body. Gravity doesn’t help or hurt the maneuver after it’s completed.
Although I’m sure the universe will be responsible somehow, right?

[Silvertiger]

Hm...there must be a reason that it's also known as a "gravity assist," wouldn't you say? Without gravity, no slingshot maneuver could take place. They are performed to accelerate a craft without expending too much propellant...which is achieved via a "gravity assist."

[Fletcher]

That's right. The earth loses a little forward momentum (insignificant at these scales) and the satellite gains that momentum given (significant).

If the earth were a non-rotating center of the cosmos then a satellite approaching for a sling-shot gravity assist (gravity is like a string providing Cpf) from ANY direction for a direction reversal and boost would have no change in speed and it would be a wasted exercise.

But that is not what happens is it !

[Silvertiger]

I never said that a spacecraft would not be getting a transfer of momentum...I said that the "cause" is gravity. Even then Fletcher, you can still describe it as an effect of the inertial forces of the universe. The "orbital bump" would still be the result of gravity, of which the changes in speed would occur. Whether you bump off of a spinning planet or off of a spinning universe, the outcome is the same if the maneuver is around the earth. So, once again, gravity doesn't care if you're spinning or not...whether the earth spins or the universe spins makes no difference to the outcome. You just end up getting you're momentum from the stars instead of earth in this case. The sun moves with the rest of the stars around the earth, which is no different inertially than the reverse. BUT...without GRAVITY to begin with, no assists could ever take place. :)

[Fletcher]

I'm still trying to get my head around an infinite universe spinning around the earth in one day ;7)

Does not compute %7)

[Silvertiger]

I would concede that as a fair reaction. I'm going to go out on a physics limb and say that the fact that the universe does rotate is indicative that it is finite with a boundary at some distance away from us where there is no mass...but without observation to back that up it's just a guess on my part. As for any empty space beyond the stars...I do not know if there is a point where that changes either. But as far as we can see from here is 46 billion light years (93B dia) out, with no end in sight yet.

(However, I do have good reason to believe that the universe extends much, much farther than what we can see. It's a mixture of math and the bible, so this isn't quite the topic for it LOL, but I'm just amazed that there was enough information contained in the bible to actually calculate a boundary at all. I might start a thread on that if you're interested.)

[WaltzCee]

I'm still trying to get my head around an infinite universe spinning around the earth in one day ;7)

Does not compute %7)

How can the universe be infinite? As the story (no matter which story you want to believe)
goes the universe has a beginning and only so much time has lapsed since then.

My question is:

How could the universe have expanded to infinity in a finite amount of time?