Yes, yes, we know, to accelerate to light speed you need infinite energy. We figured that much. But what if you actually didn't accelerate? Now most theories involve things like hyperspace, timespace tears, etc.
My idea is to use rotation. Now, if you would normally have a super-light weight stick of say, 5,000,000,000 miles, you could rotate it very fast with relative ease. Let's say the "Stick" is 1 KG heavy for speculation. However.. The energy needed to accelerate at light speed would keep increasing, making it's relative mass higher and higher. Even if the end tip would be spinning at 290,000 KM/second, it would be around 1,3 KG. But the closer you approached C, it would be heavier.. At a speed of 299,999.999.999 it would already be over 6000 megatons... This is because the rotation needs to accelerate.
But.. what if you used an extendable chain, and extended it while already having the rotation present? This way, no energy would be needed for the acceleration, only for maintaining the rotation. For example, let's say we have a 0,1 LY long chain of super-light material. Extend this chain 10 meters, and get it to a speed that will equal C2 if at chain length of 0,1 LY. Then, just extend it. The energy needed for maintaining the rotation will be pretty large, but acceleration energy will remain null because the rotation speed remains equal.
Now, please tell me why this couldn't work? I'm sure it couldn't or someone would already have thought of it -.-.