The Laws of Thermodynamics currently represent energy and matter as not being able to be built from nothing nor destroyed into nothingness.

This proves that every atom and sub-atomic particle in your body has existed since they were first created (by means we are still unsure of), and that they will continue to exist indefinitely. You have literally existed since the dawn of time and will exist. Whether you recall this past existence or not has nothing to do with the scientific validity of this law.

You are eternal, you are immortal.