Google result for 反常识的 is "unconventional". It doesn't seem to fit the description in the context you described.
I think the word you are looking for is [ "inconceivable" (adj): beyond reason, belief ] - implies a finding seemingly defies the law of physic or conventional believes
"inconceivable" in Chinese is 不可思議; 無法想像
Side note:
If an experiment's result seemingly defies the law of physic, the most likely cause would be: 1. Mistakes were made during the experiment. 2. Someone forged the result 3. The previous notion was wrong.
Edit (add from my comment):
反" contains the meaning of 'to counter' . Therefore, someone think "Counter-intuitive" contains the word 'counter' must be the right answer and my answer suggested giving up the phrase "反常识的" and use "不可思議" or "無法想像" to describe "a surprising and unusual phenomenon" . Actually "counter-intuitive" is not much different from "unconventional"- meaning something that is not conventionally done or intuitively thought
For example: A green button instead of a red button activate self-destruct command is 'counter-intuitive' because we usually label dangerous function with the color red. I would translate 'counter-intuitive' as "違反直覺的" and "反常识的" as "against common sense"