[Jedi Master Pikachu]

You can end a sentence with a preposition, if that is what you are referring to. (or, if that is to what you are referring).

And especially in ordinary conversation.

[traderrob6]

I am not an English major so I am by no means an expert, however, basic grammar tenets generally hold that “one should not end a sentence with a preposition when one has a graceful alternative.”

“For the time being, this is the only violation of special relativity that I know of.” could have easily been stated this way: For the time being, the only violation of special relativity that I know of is this. or For the time being, this is the only violation of special relativity of which I am aware.