A  201  g lead ball at a temperature of  88.1°c is placed in a light calorimeter containing 178 g of water at 24.5°c. find the equilibrium temperature of the system.

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

3. dark matter

empty space could also be a simple vacuum