Changes

== Problems for uniformitarianism posed by tidal lock ==

== Problems for uniformitarianism posed by tidal lock ==

Tidal locking is as likely to happen to the primary as to the moon. Indeed, [[Pluto]] and [[Charon]] are mutually locked. But tidal lock has its most profound implications for the Earth-Moon system. Though the presence of tidal locking might appear to militate in favor of a great age for the solar system, the dynamics of tidal lock suggest youth, not age.

Tidal locking is as likely to happen to the primary as to the moon. Indeed, [[Pluto]] and [[Charon]] are mutually locked. But tidal lock has its most profound implications for the Earth-Moon system. Though the presence of tidal locking might appear to militate in favor of a great age for the solar system, the [[Dynamics (physics)|dynamics]] of tidal lock suggest youth, not age.

As earth's rotation decreases, the moon must recede from the earth, or else angular momentum is not conserved (see above). Therefore, the rate of deceleration of Earth's rotation must itself decelerate over time. For that reason alone, the Earth-Moon system cannot be more than 1.2 billion years old, because at such a time the Earth would have been rotating dangerously fast, and the Moon would have been touching the Earth.

As earth's rotation decreases, the moon must recede from the earth, or else angular momentum is not conserved (see above). Therefore, the rate of deceleration of Earth's rotation must itself decelerate over time. For that reason alone, the Earth-Moon system cannot be more than 1.2 billion years old, because at such a time the Earth would have been rotating dangerously fast, and the Moon would have been touching the Earth.