Time travel

From eg

if time travel were to exist, it would create a rather huge opportunity for hackers to exploit systems.

As long asserted by writers of Doctor Who, the popular British TV series, some scientists now claim that there is no inherent paradox involved in time travel. At least, no more than other forms of inaccessible user experience - the basis of THE joke. This further blurs the distinctions between various forms or species of trolls: some of divine origin, some bots, some alien, some with similar psychology but direct experience of the future. How can you tell them apart?

This is also an argument never to use troll as a singular noun, as the same troll may be re-appearing in multiple time frames, even simultaneously.