Question

whay is special relativity theory? what is the link between light year and time travel

Answer 1

If you travel at speed of light the time will be slow for you but for others it will be normal

if you travels 1day with the speed of light there will be 10 years in other place.

Answer 2

special theory of relativity is generally simple than "general theory of relativity"

special theory tells us that mass and energy are not 2 different entities but one very similar entity . it tells us that mass is a form of energy
=> it states that space and time are interwoven as spacetime and the body with mass curves this spacetime due to which we visualize gravity


=> Einstein stated that gravity is nothing but an illusion , when a body of mass curves the fabric of spacetime the another body follows the circular motion along the orbit of body


=> Einstein stated his famous equation E = MC² in this theory where m is mass (which is constant ) , c is light's speed in vacuum (which is also constant ) , and E is energy

and several others points he has discussed , I have not mentioned , be sure to look it up on internet


light year is measure of distance and time travel is totally a different concept


hope this helps