I have 1999 Daewoo Legenza, the car ran out of oil and the enige locked and won't start up again. Is the whole engine gone or is thee a way to fix it.
If you fill the evacuated chamber with air, eventually air's imperfect transparent media properties of absorptivity and Raleigh scattering would come in to play. If you keep the chamber evacuated and the walls behave as a perfect white body, your beam of light would reflect indefinitely. It would never be detected, because detection of light requires some absorption.
I have two bikes. One has a large chain and the other has a large cable lock. Each one also has a small cable to secure the seat. I don't live in a high theft area, but I still chain the bike around the front and back wheels and some stationary object. If you get the back wheel, you also secure the frame. I've heard good things about those U locks, but I never tried them because my locks work as they are. If I were you, I'd park my bike in a different place every day and bring it in at night. Also, if you keep it long enough, it will begin to look old and beat up. You can keep it in good working order, but that run down look is a major theft deterrent. Good luck!