airplanes

A key challenge in building electric aircraft involves how much energy can be stored in a given amount of weight of the onboard energy source. Although the best batteries store about 40 times less energy per unit of weight than jet fuel, a greater share of their energy is available to drive motion. Here's more on why batteries are, relatively speaking, heavy for aviation.
There's a silly article in Wednesday's Washington Post which suggests that you're better off eating your hideous airplane meal while sitting on the toilet, rather than in your seat using the tray table. It's not just silly. It's scientifically impossible.