The technology needed to make true interstellar travel viable is completely beyond us. 100 years? Could be 1000 years or frankly never.
There are several areas where we are barely more advanced than a if we'd just been hit on the head by an apple

Look at the variety of methods that sci-fi writers use to bridge these huge gaps.
Take Star Trek as it's one of the most thoughtfully explored methods of interstellar travel (and the article mentions Urhura and Geordi).
Just off the top of my head, some of the things that the creators have invented to allow 'Warp drive' to happen.
Controlled Anti-Matter reactions (some basis in reality)
Dilithium crystals
Warp bubble/static warp field
Inertia dampeners
Navigational deflector array
Anti and artificial gravity
So even in the minds of those who write sci-fi when helped by real scientists (as ST-TNG was) the answer to interstellar travel is a mixture of technology that we can possibly aspire to, with technology that we can imagine but is completely beyond us and imaginary 'elements' to make it all work.
For true interstellar travel to be a century away, we literally need to find a derelict alien spaceship or hyperspace gate then have a century to back engineer it.