to #71, CTS:

There are a few possible exceptions to all your explanations. :)

1) Time travel requires use of massive scale phenomenon, and manipulating something like black holes into exotic configurations to produce a proper wormhole that was large enough to not simply squeeze your ship into a thin stream of atoms. This would prevent casual/easy use, and might be very limited in aiming, such as going only so many years&days back in time, so the exact same amount of time passes on each end of the portal.

2) Time travel is like the idea of a teleporter, that requires a sender and received. So you can't Time Travel to any point before the activation of the very first receiver.

just some thoughts :-D

To Chris, #25

you can only see light if light comes into contact with your eye

lasers are very focused light. This means *ALL* the light goes in one direction. The only person who might ever see a glimpse of a laser beam in space would be the person whose eyeball it just seared through.

Even in atmosphere, unless there is dust, fog, or something else to cause some of the light to go off in different directions, a laser is invisible.