In Einsteins relativity theories, he made the example of light travel vs. time on earth. Example: Traveling for 1 year at the speed of light equals 60 years on earth, or to that effect. 10 light days is nothing comparable however, since the closest star (Proxima Centauri) is about 4 light years away. 10 light days is feasible travel time compared to years. 1 light year equals 365 light days or 1/365 x 365. 1/365 x 10 =.0274 light years. Use these number with 60 years and you'll have the time used for travel. These are basic figures, and some of them are based on theory. Quantum Mechanics brings the subject to another level. Light travel is still a theoretical subject which may have no clear answer for a long time.