Why do we not know yet if we live in a 'multiuniverse"?

The multi-universe, or “multiverse”, theory can’t be proved or assumed without empirical evidence of other universes - simply supposing the condition isn’t enough to know it’s true.

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.