When it comes to space, there's a problem with our human drive to go all the places and see all the things. A big problem. It's, well, space.
It's way too big. Even travelling at the maximum speed the Universe allows, it would take us years to reach our nearest neighbouring star.
But another human drive is finding solutions to big problems. And that's what NASA engineer David Burns has been doing in his spare time.
He's produced an engine concept that, he says, could theoretically accelerate to 99 percent of the speed of light - all without using propellant.
He's posted it to the NASA Technical Reports Server under the heading "Helical Engine", and, on paper, it works by exploiting the way mass can change at relativistic speeds - those close to the speed of light in a vacuum. It has not yet been reviewed by an expert.
Understandably this paper has caused buzz approaching levels seen in the early days of the EM Drive. And yes, even some headlines claiming the engine could 'violate the laws of physics'.
But while this concept is fascinating, it's definitely not going to break physics anytime soon.
As a thought experiment to explain his concept, Burns describes a box with a weight inside, threaded on a line, with a spring at each end bouncing the weight back and forth.
In a vacuum - such as space - the effect of this would be to wiggle the entire box, with the weight seeming to stand still, like a gif stabilised around the weight.
Overall, the box would stay wiggling in the same spot - but if the mass of the weight were to increase in only one direction, it would generate a greater push in that direction, and therefore thrust.