Wormhole (Earth-6531)

"There is the possibility that this could be the precursor to the opening of an Einstein-Rosen bridge, also known as a wormhole. In layman's terms, a portal to another region of space opening below the ozone layer."

- - Erik Selvig to Nick Fury

A Wormhole, also known as an Einstein-Rosen Bridge, is a portal created from energy that enable fast travelling between different regions of space, as well as to other dimensions.

History
The New Gods of Apokolips developed their own forms of wormhole, which they called Boom Tubes, allowing them to travel instantaneously to locations, which they extensively used to conquer other worlds.

The Asgardians built and used the Bifrost to produce wormholes and travel to different regions of the galaxy, such as the other worlds connected to the Yggdrasil.

In 1945, during World War II, the Red Skull, leader of HYDRA, attempted to use the Tesseract to reach the Chaos Realm and free the Ogdru Jahad from their crystalline prison. When this plan failed, he tapped into the Tesseract with his bare hand to use it against Captain America, causing him to be transported by a wormhole to the space-time continuum.