Actually, in theory there is one place denser but our models show it can never happen.
The moment right after the big bang. As energy can never be created nor destroyed, all the energy in the universe was practically in one point in space-time a femtosecond after the big bang.
The moment right after the big bang. As energy can never be created nor destroyed, all the energy in the universe was practically in one point in space-time a femtosecond after the big bang.