In relativity theory, Einstein introduced mass as a new type of energy to the mix. Beforehand, the mass of something in kilograms was just a measure of how much stuff was present and how resistant it was to being moved around.
Set the broiling pan in the oven once the broiler has warmed up. Make sure the sausage is positioned about seven to nine inches below the heat. Cook for 16 to 20 minutes total, turning the brat 90 degrees every four to five minutes so that it cooks evenly on both sides.
Pour 2 (12 ounce) bottle of beer in a 3 qt pot. Add butter to melt. Let it get hot first and add the bratwurst and sliced onions inches Cook, simmering the beer and turning the brats every 10 minutes for about 30 to 45 minutes (use your own judgment). Let the beer evaporate and reduce it until it is syrupy and to where it looks like it is coating the bratwurst well.