I feel if there is no evidence or proof of something that it does not exist. Unless we all agree upon its existence through evidence.
For example we We SAY that 0 is the middle but it's not necessarily something tangible or physical. It's just something that (we all agree on), like universally 1 inch is 25. 4 mm and it's not going to change until we abandon metric and imperial measurements.
We all need evidence in order to believe in its existence.