Final answer:
The universe is thought to be very close to flat, indicating it will expand forever which aligns with recent findings in cosmology. The cosmological constant, introduced by Einstein and reinstated in recent theories, plays a crucial role in this perspective. Overall, the universe can be considered a closed system in thermodynamic terms, while also being on the brink of being open in spatial terms.
Step-by-step explanation:
The question of whether the universe is open or closed is a central topic in cosmology. The universe is considered closed if it is positively curved, meaning if you travel far enough in any direction, you will eventually return to your starting point. Conversely, an open universe is negatively curved, suggesting you could travel infinitely without returning to your starting point. The debate has evolved with the introduction of the cosmological constant, first proposed by Einstein but reintroduced into contemporary physics, affecting the dynamics of cosmic expansion. Recent observations, such as those related to the cosmic microwave background radiation (CMBR), indicate the universe is very close to flat, which supports an eternally expanding universe within the inflationary model of cosmology.
Furthermore, thermodynamics and bioenergetics underscore the concept of the universe as a closed system concerning energy exchange: energy neither can be created nor destroyed, in line with the first law of thermodynamics. However, local systems within the universe are open, always exchanging energy and mass with each other. The flat universe aligns with general relativity, which implies that matter creates the space it occupies, setting a special symmetry in a flat universe. Thus, the consensus among most researchers, following the experimental discovery of the cosmological constant, is that the universe should be just barely open.