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We summarize the variety of roles played by dust grains in the interstellar medium of the Milky Way galaxy. These range from the passive extinction of starlight from interstellar clouds to the active surface chemistry that provides the seminal molecule, molecular hydrogen, which controls all of gas-phase interstellar chemistry. The products of this gas-phase chemistry control the formation of stars and planets. Finally, dust grains have an essential role in the chemistry that forms complex organic molecules. These molecules include some species that are the building blocks of biological molecules; these building blocks are delivered to planets during and after planet formation. Evidently, dust grains may be related to the existence of life on planets. We speculate on the existence of technological civilizations elsewhere in the galaxy by considering the well-known Drake Equation. We end by noting that the Universe might be regarded as a machine for producing life, and that dust grains are an important – indeed, essential – component in that machine.

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