This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Krasnikov. This is diagram for Krasnikov Tube which User Ben Standeven have created en Ben Standeven en Ben Standeven original upload log page en Krasnikov Ben Standeven bytes no is diagram for Krasnikov Tube which User Ben Standeven have created General relativity Spacecraft propulsion Special relativity Time travel Pseudoscience