If gravity is not a force pulling inward, and escape is not about overcoming attraction, then a deeper question follows:

What does it mean to orbit at all?

In the standard picture, an orbit exists because an inward gravitational force is continuously balanced by outward inertial motion.
In a mechanical-medium picture, that language is unnecessary.

An orbit is a neutral stress trajectory.

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The Conventional Formula, Reinterpreted

Orbital speed is usually written as$$v^2 = \frac{GM}{r}$$

This is often read as:

“The speed needed so centripetal force matches gravitational pull.”

Mechanically, the same equation emerges from a very different requirement:

the speed at which a moving defect experiences no net stress imbalance.

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Inward Stiffness Gradients

From Series X.1, gravity is a radial stiffness gradient produced by internal stress.

Near a massive body:

• the medium is more compressed,
• wave speeds are altered,
• restoring responses are stronger.

A stationary defect will drift “down” this gradient—what we call falling.

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Motion Produces Outward Resistance

When a defect moves laterally through a stiffness gradient:

• it resists redirection due to inertia,
• circulation interacts asymmetrically with the medium,
• outward stress appears as a geometric effect.

This is not a force—it is resistance to curvature of motion.

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Orbit as Stress Equilibrium

An orbit occurs when:

• inward stiffness gradient
• is exactly balanced by
• outward inertial resistance to bending the trajectory.

At that speed, the defect follows a path where:

• stress gradients are tangential,
• no net radial reconfiguration occurs,
• and the medium does not demand correction.

This is why orbits persist without continuous adjustment.

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Why the Speed Is Exactly What It Is

The balance condition is:$$\text{inward stiffness gradient} \;\sim\; \frac{v^2}{r}$$

Using the mechanical result from Series X.1:$$\nabla S \sim \rho R \frac{1}{r^2}$$

gives:$$v^2 \sim \frac{GM}{r}$$

The familiar formula survives because:

• it encodes a balance condition,
• not a force law.

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Why Circular Orbits Are Special

Circular orbits are not privileged because they are simple.

They are special because:

• stress balance is uniform,
• no radial oscillation is required,
• and energy exchange with the medium is minimized.

Elliptical orbits correspond to:

• periodic excursions through slightly imbalanced regions,
• with energy traded back and forth as waves.

Nothing mysterious is happening—just stress redistribution.

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Why Orbits Decay (or Don’t)

If the medium were perfectly elastic:

• orbits would persist indefinitely.

In reality:

• small dissipation exists,
• wave emission slowly drains energy,
• and orbits can decay over very long timescales.

This explains:

• atmospheric drag,
• tidal evolution,
• orbital circularization,

without invoking additional forces.

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No Action-at-a-Distance Required

At no point does anything “reach out” to pull the orbiting body.

The medium:

• locally enforces stress compatibility,
• responds to motion,
• and guides trajectories naturally.

An orbit is simply the path of least mechanical resistance.

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Key Takeaway

Orbital motion is not sustained by attraction—it is maintained by stress balance in a stiffness gradient.

The orbital speed is the speed at which inward and outward mechanical responses cancel.

With orbits understood this way, the next question becomes practical and tangible:

Why do large bodies become spherical, while small ones remain lumpy—and what sets the boundary between them?

That is where we turn next.