In Norse Mythology the bridge leading from the realm of the mortals Midgård to the realm of the gods Asgård. The bridge itself is the rainbow and its guardian is the god Heimdall. The bridge is destroyed at the end of the world, Ragnarok. It as built by the Aesir.
... or immoral, technicians apply all sort of useless treatments. Examples include pulsing an electrical current through the body to kill 'the bad cells', this has no effect ...