Spectrometers are one of the most important tools in science. By measuring the various properties of light coming from or bouncing off an object, the device can help scientists figure out what paint is made of, or detect the composition of faraway stars. In the past, the machines have been too large to really be used anywhere but the lab. But now researchers from MIT have used quantum dots to make spectrometers that can fit in a smartphone, according to a study published yesterday in Nature. Having all that computational power in the palms of their hands could help scientists diagnose of diseases (especially skin conditions), test urine samples, or identify food contaminants.