What would be the largest possible particle accelerator if all the matter-energy of the universe was used to build it ? How far down in sizes could we probe ? I think as of now we can probe 10^-10 mm (?) but to probe even 10 times smaller you would need an accelerator 10 times bigger so it would already be 100 km. Now if we had a trillion km long accelerator in theory how far down could we see , 10^-100 mm ? what are the physical limits ?