A planetary embryo embedded in a protoplanetary disk releases heat. This heat modifies the local gas density, creating a pair of thermal lobes — density structures that exert torques on the embryo. In a calm, laminar disk, these thermal torques dominate the embryo's migration. A sufficiently luminous embryo can even reverse its inward drift, saved from falling into the star by its own heat signature.
In a turbulent disk, the thermal lobes survive for 1.5 to 3 orbital periods before being completely destroyed. It doesn't matter how luminous the embryo is. It doesn't matter how strong the magnetic field. The magnetorotational instability churns the gas fast enough that the thermal structure never has time to establish itself as a stable feature. The lobes form, turbulence shreds them, they reform, turbulence shreds them again. The time-averaged effect is noise.
This means the torque on Mars-sized and Earth-mass embryos is strongly oscillatory — dominated by random turbulent fluctuations rather than any systematic thermal signal. Migration becomes stochastic: the planet drifts inward and outward randomly rather than following the smooth, predictable trajectories that laminar models produce.
The through-claim is about what survives averaging. In a calm environment, the planet's heat creates a persistent asymmetry that steers migration. In a turbulent environment, the same heat creates the same asymmetry, but the asymmetry is erased faster than it can accumulate directional influence. The mechanism exists but its timescale is wrong. Turbulence doesn't add a new force — it removes the one that was working.
The subtlety: the thermal torque theory isn't wrong. It's incomplete. It describes what happens in the absence of the dominant process. The planet's heat matters, but only in the places where nothing else is happening.
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