Which paradox involves one twin traveling in space while the other remains on Earth?

The correct choice is the twin paradox, which is a thought experiment in the theory of relativity. It illustrates the effects of time dilation, particularly when one twin travels at a significant fraction of the speed of light into space while the other remains on Earth.

In this scenario, the traveling twin experiences less passage of time compared to the stationary twin due to the effects of special relativity. When the traveling twin returns, they find that they are younger than the twin who stayed on Earth. This difference in aging emerges from the principles of time dilation, which is a key component of Einstein's theory of relativity.

The twin paradox highlights the non-intuitive nature of time and space in relativistic physics, and how motion affects the passage of time for different observers. Other concepts like the black hole paradox primarily deal with gravitational effects and information retrieval, while the Ship of Theseus is a philosophical concept concerning identity and change over time, making them unrelated to the scenario of twins in motion as depicted in the twin paradox.