One way that you might want to deal with this is find a Hard Sci-Fi setting and you and your players get to know that setting very well, either from an RPG or a novel or TV show. The feel will come in playing to that setting, rather than the science behind the setting.
Another possibility is play a game that emphasizes the difference between users and creators of technology. If, for example, the PCs are all a special forces unit during a hard sci-fi space war they as players do not have to have any more understanding of the science than the PCs would, which might be no more than "If I point this and push this the thing that I pointed it at dies." To make a fantasy analogy consider the barbarian and the magic sword. The barbarian doesn't have to know how to make a magic sword or any magical theory behind it, he only has to know how to use it. In modern terms consider all the people who use computers but have no idea how to program, or even how to install a program. All they have to know is what it takes for them to use it. At time the PCs are still going to have to figure out clever uses for the gear they have,it doing clever and heroic stuff is what makes them PCs, but they can do that with the info you have given them and a basic understanding of science in general rather than the knowledge of a disciplined proffesional.
If there is something that they really need to know, focus in on it in the setting introduction. If its nanotechnology, for example, can you find a popular science magazine's article about it for them to read that would give them enough info to play with?
Also, don't dismiss that you can say "physics doesn't work that way". In 1906 the most brilliant scientific minds were debating things we take as fact today. So what might be mere theory in 2006 might be firm fact in 2106. As long as you have a rational explination that functions within the confines of what is known and what might be known you can play the game.
I always seem to have to ask this question: you say you want to run a hard sci-fi game, but do you have players who want to play it? Even if the answer is yes, do you have players who care if they just roll a Kn(physics) check to solve the problem? They may not.