Measuring the Speed of 'Light' with a Microwave Oven?killing raven sun wrote: ↑Fri Jul 27, 2018 6:39 ambtw, the speed of light in a vacuum is a fun thing to talk about but does not exist irl, space is not a vacuum, the speed of light through the interstellar medium is not guaranteed and cannot be measured from one distant observation, using light to measure distance or speed is pure speculation
-- Make a slab of ice, cheese, or chocolate, 1 / 2 inch thick, the same shape and slightly smaller than the bottom of your microwave oven. -- The hardest part is: DON'T make the slab in a metal or foil pan. Either make it in glass, or else you have to take it out of the pan when it's solid. -- Put the slab in the microwave. If there's a turntable in the microwave, turn it off or take it out. The slab has to remain still. -- Start giving it 15- to 20-second shots of cooking power, until soft spots begin to appear in the slab. When there are enough soft spots, you'll see that they're laid out like a checkerboard, in rows and columns of spots. -- Carefully move the slab from the oven to a piece of newspaper spread out on the table (so you don't make a mess). -- Measure the distance between two spots in the same row or the same column. It's hard to tell where a soft spot begins, or where the center of it is, so you'll have to make several measurements and try to get a good average, reliable number. It'll be 6.12 centimeters. That's half of the wavelength of the microwave cooking power. -- Now look inside, under, around, on the back, top, bottom, or side of the oven. Find a little metal plate that shows the manufacturer, model number, input power, and cooking power. Also on that plate, it'll tell the operating frequency of the oven. All microwave ovens operate at the same frequency. It will say either " 2.450 GHz " or "2450 MHz ". Those are both the same number. -- Now you have the frequency and the wavelength. Speed is their product. (0.1224 meter) x (2,450,000,000 per second) = 299,880,000 meters per second. The official standard speed of light in vacuum is 299,792,458 , slightly less in air. These numbers are less than 0.03% different. That's more accurate than the speed was known before the 1880's.