Ask HN: Is anyone seriously working on a space drive?

There are plenty of serious companies looking at "rockets", and alternative launch and propulsion methods to get us somewhere more or less in the "local" space of our solar system, but are there any serious attempts at creating and testing anything that might lead us to travel to the stars?

I've seen a load of crackpot stuff but very few genuine efforts. Is there even anyone looking at challenging the science in a significant way that might lead to something?