This is speculative. Grand Unified Theories suggest protons might decay over 10³⁴ years. If so, matter is not eternal. If not, white dwarfs could turn into cold iron spheres.
The following table summarizes frequent test and quiz questions found in study guides: (PDF) The Origin of the Universe - Academia.edu origin of the universe questions and answers pdf
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Science is neutral on this. The Big Bang describes how the universe evolved, not why it exists. Some theologians accept it as the "moment of creation"; others reject it. Science cannot test supernatural claims. This is speculative