Simple time loops
Time-travel issues
are illustrated by causal loops involving an amplifier (cone) and
inverter (cone with knob), with negative time delays (double-cone
structures) to cancel their forward delay. The amplifier loop is
consistent, while the inverter loop is a simple example of
paradoxical time travel. Depending on its representation, the
inverter loop's signal can either hover at a value intermediate
between 1 and 0, exist in a mixture of 1 and 0, or refuse to appear
at all. Or the components of the circuit can mysteriously fail! The
paradoxical loop eliminates the possibility that the circuit will
work normally, and thus brings to the fore a host of otherwise less
likely alternatives.
Examine the figure in 3D.
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