The children of Syria don’t have a voice, so rock star physicist Stephen Hawking is lending them his.Hawking is a man who knows what it's like to live without a literal voice. And in case you missed his op-ed in the Washington Post and elsewhere, he feels passionately that the youth of Syria need people to speak about the injustice they're suffering.On this, the third anniversary of the conflict, with both sides escalating the violence and targeting civilians, Save the Children U.K. is pushing hard for more international attention. Earlier this month, the group struck publicity gold with its gut-wrenching "Most Shocking Second a Day" from Don’t Panic, which has been viewed more than 27 million times.Created by agency adam&eveDDB, the new spot below featuring Hawking isn't as visually stunning as the nonprofit's viral hit, but it is conceptually perfect.Unlike the earlier video, we aren't seeing a fiction. We are seeing the real children of Syria whose lives have been torn apart. As we contemplate their portraits and realize these kids could be any kids from our block, Hawking's unmistakable speech synthesizer gives voice to their words. It is a voice that is no less moving for the lack of inflection. And this time, the call to action is explicit."The children of Syria have no voice. That is why I'm giving them mine. What will you give?" he says. We're prompted to enter an SMS code to automatically donate to Save the Children U.K. And we'd better listen. If we don't, says Professor Hawking, our apathy could mean the very downfall of our humanity, for without the universal principle of justice, "before long, human beings will surely cease to exist."