There were apparently 40 ‘paradoxes of plurality’, attempting to show that ontological pluralism—a belief in the existence of many things rather than only one—leads to absurd conclusions; of these paradoxes only two definitely survive, though a third argument can probably be attributed to Zeno.

A temporal paradox, time paradox, or time travel paradox is a paradox, an apparent contradiction, or logical contradiction associated with the idea of time and time travel. In physics, temporal paradoxes fall into two broad groups: consistency paradoxes exemplified by the grandfather paradox; and causal loops.

In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more.

Memory allows us to mentally travel backward in time as well as into the future, explained Tulving, a University of Toronto professor emeritus and visiting professor in cognitive neuroscience at Washington University, in a presidential invited address at APA’s 2003 Annual Convention in Toronto.

In psychology, mental time travel (also called “chronosthesia”) is the capacity to mentally reconstruct personal events from the past (episodic memory) as well as to imagine possible scenarios in the future (episodic foresight / episodic future thinking).

Travelling in time might sound like a flight of fancy, but some physicists think it might really be possible. BBC Horizon looked at some of the most promising ideas for turning this staple of science fiction into reality. Ron Mallett has a dream: He wants to travel in time.

Using a quantum computer to simulate time travel, researchers have demonstrated that, in the quantum realm, there is no ‘butterfly effect. ‘ In the research, information–qubits, or quantum bits–‘time travel’ into the simulated past.

While human teleportation currently exists only in science fiction, teleportation is possible now in the subatomic world of quantum mechanics — albeit not in the way typically depicted on TV. In the quantum world, teleportation involves the transportation of information, rather than the transportation of matter.

In reality, we can’t pass particles of matter through most materials because they interact too strongly with the atoms inside. That gets to the key problem with any kind of teleportation: The matter making up our bodies obeys rules that aren’t conducive to speeding across open space and through barriers.