If it ain't forbidden...
...it's mandatory, according to Quantum Mechanics, and as far as we've seen humans are subject to bio-physical law like the rest of Nature. The various stages of physical manipulation like Kardashev's schema and others are physically plausible and invoke a minimum of assumptions.
You're right about the future being "unknowable" but as the principle of unitarity in QM and of actualism in geology suggests, the more things change, the more they stay the same.
Adam