Are the theories on gravity disproved or gravity is replaced by plasma or something?
I am not quite sure what you are asking. The theories of gravitation are not complete but are INCREDIBLY accurate even so. Newton’s “law” of gravity is still more than sufficient for sending probes to Mars etc whilst Einstein’s more advanced Theories of Relativity have been experimentally verified time and time again. SO not disproved at all – at least to my knowledge and I think I would have heard if they were. I think the plasma theories you refer to are a highly controversial and not widely accepted theories of star formations. Fred Hoyle was involved with them I think.
