In science, when we don't have proof for something, that something doesn't exist.
This is because science can't demonstrate the non-existence of something. The scientific-method is not made to fulfill that purpose.
Though the fact that many hypotheses, who initially began with no proof beyond the words and crossed fingers of its supporters (which according to you these processes didn't exist before they were proven), were later proven and even accepted by mainstream science.
Here's my favorite Example:
In 1911 Einstein published his Theory of General Relativity, the most controversial part of the theory stated: "Gravity distortion of the structure of Spacetime by matter, affecting the inertial motion of other matter". In layman's terms: "gravity distorts space around sufficiently large objects". Obviously this would be difficult to prove and, for years, very few scientists took it seriously.
However, there was one way to prove it. During a solar eclipse you can see the stars closest to the sun and some that are supposed to be behind the sun (this happens because the sun's gravity affects the direction light travels around it). Taking a picture of that would prove Einsteins theory, so in 1911 he challenged observatories to take a picture of this event. In 1917, several did so and came back with nothing.
However, in 1919, Sir Arther Eddington led an expedition to Africa to take a photo of the Solar eclipse expected to occur there. His results were amazing, he managed to take a photo of the stars behind the Sun (and apparently a photo of Mercury, who was back there too), which gave credit to General Relativity and led to it being accepted by mainstream science.
Science is designed to sort out the truth from the fiction (which it is bad at), and give us an understanding of the world, solar system, galaxy, and universe around us. There are very few things that are set in stone in science (inertia is a good example), everything else has been altered or proven to be false (alchemy, enough said).
Just because it has not been proven, or even if there is evidence that seems to contradict the theory, does not mean it is nonexistent.
This has nothing to do with God, just making a point that things can exist before they are discovered.
"
absence of evidence is
not evidence of
absence"
(Taken to offer a third option of "not enough evidence to sufficiently prove or disprove the claim")