Real scientists determine what is true by using the Scientific Method, a procedure that lets reality speak for itself, rather than be misinterpreted by opinion.
To man, reality may exist in two forms, that which is Objective and that which is Subjective.
Things that exist that are not open to interpretation. All objective reality can be proved to exist no matter what one believes.
All matter. Matter cannot be created nor destroyed, but may be changed in form/converted into energy.
Things that exist that are subject to interpretation. All subjective reality can be proved to exist, but the experience of it may vary among individuals.
The experience of warmth. Without question, heat exists, and heat is what makes us feel warm. However, at a certain temperature, one may feel warm or cold.
Things that do not really exist but may be believed by many to exist. A myth can neither be proved nor disproved under any circumstance, because it simply does not exist.
All gods. There is no proof of any kind that any god really exists.
There is nothing that exists outside the realm of physics.
A state of nothingness cannot exist, for if it exists, then it must be something, which cannot exist if there is nothing. This is why the "Big Bang" theory begins with a "Quantum Singularity" and not nothing.