We know precisely what each joule and nanowatt will achieve and its knock-on effects in the global ecosystem as a whole.'

A surface area of one square meter on Earth receives one nanowatt of power from a single star of apparent magnitude +3.5.

By the time a signal transmitted from the tower hits your cell phone, it will be in the W (microwatt) or nW (nanowatt) range.

Then, if you increase the power 100 fold (e.g., to less than a nanowatt), the photodiode is fooled into reporting the arrival of a single photon.

As this substance decays, it produces beta particles, high-energy electrons that now yield nanowatts (one nanowatt is one-billionth of a watt) and may soon, the inventors hope, yield microwatts.