Is this a hot cup of tea? Or the power supply for the computer of the future?Researchers in Singapore have shown, in principle at least, that it will soon be possible to create thermal logic gates, including AND, OR, and NOT gates. Once you have all those pieces, you've got the basic ingredients of a computer that runs directly on heat, with no need for electricity at all.Lei Wang and Baowen Li of the National University of Singapore propose that their logic gates could soon be built of recently developed thermal transistors or related designs, which control heat flow in the same way that conventional transistors control electricity. A thermal transistor turns on or off depending on whether the temperature at its input gate is above or below a critical temperature. Constant temperature heat baths would take the place of power supplies in operating the thermal transistors and logic gates. In theory, any heat source could be used to run a thermal computer - sunlight, the heat from a campfire, etc.In addition to proving that thermal gates can perform all the basic functions of electronic gates, the authors of the research soon to be published in the journal Physical Review Letters point out that the work may also help us to understand the complex heat flow in biological cells and systems in terms of thermal logic.To get a look at the research before it's officially published, you can download a preprint of paper from the online science archives.