We've seen two-way displays and undercover mirrors before, but the latest two-faced invention to come from the depths of the National Institute of Advanced Industrial Science and Technology (AIST) can pull double duty in regard to purpose and save a little energy in the process. The "switchable glass" has certain reflexive properties created by the twin coatings of "40-nanometer-thick magnesium-titanium alloy, plus a 4-nanometer-thick layer of palladium," which allows for the mirror to become transparent when a small amount of hydrogen is introduced between the two panes. Alternatively, tossing in a bit of oxygen forms a reflecting mirror, allowing users to "switch" the glass by injecting gases. Contrary to other commercialized approaches, this rendition can purportedly result in up to a "30-percent savings in energy costs" by having to run your air conditioner less, but there's still work to be done. Scientists at the AIST are still toiling away as they try to fight the relatively rapid deterioration that occurs from "frequent switching," but if they can add a dash of durability and get the price down to a respectable level, we could all be living in a house of mirrors before too long.