Short answers, pulled from the story.
Oceanic lithosphere averages about 50 kilometers thick near mid-ocean ridges but grows thicker over time as it cools. Continental lithosphere typically measures around 150 kilometers in thickness, though this varies significantly between mountain ranges and stable cratonic interiors.
Scientists using magnetic instruments adapted from World War II submarine detection devices began mapping odd variations across the ocean floor in the 1950s. The theory gained acceptance after magnetic striping data was published between 1961 and 1963.
Arthur Holmes proposed convection currents within the mantle as a driving force during the 1920s and 1930s. Alfred Wegener described his theory of continental drift in a 1912 article before expanding it in his 1915 book The Origin of Continents and Oceans.
Earth stands alone among known planets currently exhibiting active plate tectonics driven by abundant water in its crust. Venus shows no evidence of current plate movement despite having experienced volcanic resurfacing events hundreds of millions of years ago.
Convergent boundaries arise when plates collide, forcing one plate beneath another in a process called subduction. Deep marine trenches mark these destructive margins, often accompanied by volcanic island arcs like the Aleutian Islands or the Japanese archipelago.