I could fly at 17 times the speed of light, which should get me well into the galaxy and back.
My objective would be to find an intelligent form of life on another planet somewhere...and bring back evidence of the find. Hard to do in a day, but I'd try.
I reckon that's the type of evidence that might help people on earth behave differently with each other. Hopefully in a good way by reminding them of their place in an infinitessimal universe, where really the only things that matter are how we affect other people in our short time here.