https://phys.org/news/2018-06-starshot-qa-harry-atwater.html > It is a multi-disciplinary $100-million project that was announced in 2016, aimed at designing a spacecraft that can be launched to planets surrounding other stars and reach them within our lifetime. The idea is to develop spacecraft that are capable of traveling at nearly 20 percent of the speed of light. > Why can't that be done with conventional rockets?