Time Travel: A Danger To Us All? Possibly.

Please don't worry about potential abuses of time travel. When a physicist says a thing is "possible," you may need to take that with an infinite grain of salt. A physicist will smile and tell you (and so will I) that a thing is "possible" - even if it is impossible to put into practice without requiring:

A) novel and exotic kinds of matter that do not as far as we know exist, that are not even theoretically predicted to exist

B) amounts of energy exceeding the total amount of energy in the universe

C) unknown effects capable of spontaneously collapsing or nullifying the various forces of attraction/repulsion that create matter's solidity (it isn't the miniscule particles that make matter solid, after all - it's the powerful forces that those particles anchor)

Physicists are always happy to admit a thing is possible, as long as you don't mind giving them givens that do not exist, and in all probability, never will exist. There are many things that may under certain "given conditions" be not impossible, that will nevertheless not at any point become possible.

Not to be a downer. The practical limits the possible; that's just reality for you. Reality isn't something to feel glum about. We should all be joyous, filled with boundless optimism, anticipation and curiosity by the wonders of the universe as it actually surrounds us! It's pretty dang cosmic enough, to hang an infinity of an infinity of dreams upon, dreams that can even come true.

And it's true we can't rule most things out. So? There will be many surprises in store for us! But we do not need to play make-believe about everything that may somehow nigh-impossibly come to be, in order for the whole dang ball of masses, forces and energy to be big fat stinking amazing. Because it is. It already is.

Given only what is. Given only what we already have, given only what's established, given only the givens we have "in hand" so to speak! It already is amazing.

Almost limitlessly so.