The electronic gauge is designed for measuring wheel rolling circle diameters. Measurements are made directly on the rolling stock, without wheel set roll-out. The measurement of the diameter is ...

Measuring the black hole’s diameter can reveal its mass using Einstein’s general theory of relativity. But only the globe-spanning Event Horizon Telescope has made this sort of measurement ...

Its main array includes 25 dishes of 12m diameter ... swirling around the black hole, which is about 73 million light-years away in the constellation Eridanus. By measuring the Doppler shift ...