Bounded Mass-Energy Dynamics and the Principle of Absolute Irreversibility in a Cyclic Spacetime Model

<jats:p>This paper proposes an integrated cosmological framework asserting that the Universe is a closed physical system characterized by a strictly bounded and finite mass-energy content. Rejecting physical infinities as non-physical mathematical abstractions, it argues that a universe originating from a singularity inherently possesses a finite quantity of total mass-energy. Furthermore, it introduces the Principle of Absolute Irreversibility in 4D spacetime coordinates, demonstrating that spatial recurrence does not constitute a return to an initial state due to the unidirectional arrow of time and thermodynamic entropy progression. Consequently, cosmic evolution—spanning galactic mergers, expansion, gravitational collapse (Big Crunch), and quantum rebound (Big Bounce)—operates not as a closed circular loop, but as an endless, non-repeating spiral evolution.</jats:p>