sub create_time_machine {
    my $time_duration = shift;
    my $wormhole = sub {
        # (Creation of wormhole is left as an exercise :-)
        # ...
    };

    # Here, implement the following pseudocode:
    #    Tow wormhole close enough to the neutron
    #    star, and for a long enough period, to
    #    fix its duration at $time_duration years...

    return $wormhole;
}

# Now create time machine with desired time period
my $p = create_time_machine(1_000);  # eg. 1,000 years