Zero-point energy

Zero-point energy was, as described by Romana I, the vibrational frequency of the universe, popularised by Nikola Tesla.

He developed the idea of a tuned resonance circuit around the turn of the 20th century, thinking he could tap into zero point energy by setting up a standing wave that would resonate at a suitably high frequency. However, his facility at Colorado Springs burnt out when he tried it; the generators of the local power company couldn't supply enough current. Hsien-Ko perfected this attempt in her plan to make Magnus Greel's time cabinet arrive in the 1930s instead of 1872. (PROSE: The Shadow of Weng-Chiang)

Behind the scenes
In quantum physics zero-point energy refers to the lowest possible energy a system can have. This is not always zero, which is distinct from classical mechanics. For instance, in a (the quantum mechanical equivalent of a spring), the zero-point energy is not zero.