I intend to say something like
The grand unified theory in particle physics claims over a certain high energy, the electromagnetic force, the strong nuclear force and the weak nuclear force are united as a single force.
Is the preposition "as" above used properly? Or should I replace it by "into" or "in" or "to be"?
I found several analogous examples in Oxford Living Dictionary for unite:
‘What Newton did to simplify the planetary motions must now be done to unite in one whole the various isolated theories of mathematical physics.’
‘Well, by adding this essay, the problem and the answer are united in a comprehensive whole.’
‘The actress added how mutual cooperation made them unite into one whole being and stop thinking about who is a better partner.’
wherein either "in" or "into" is used for this function. Can "as" or "to be" also be used here?