What is the most powerful telescope in the world?

The James Webb Space Telescope is said to be the most powerful telescope in the world as of 2014. However, NASA is already building the Advanced Telescope Large-Aperture Space Telescope, which is expected to be even more powerful.

The James Webb Space Telescope, which is optimized for infrared observations, is scheduled to take flight in 2018. It is a product of 17 countries that have been working together since 1996. More than $3 billion have been spent on the project. The Advanced Telescope Large-Aperture Space Telescope, or Atlast, is set to become its successor. One of the Atlast's primary goals is to seek the presence of alien life.