Exploring explosives for expanding geothermal energy

Why are scientists setting off small-scale explosions inside 1-foot cubes of plexiglass? They’re watching how fractures form and grow in a rock-like substance to see if explosives or propellants, similar to jet fuel, can connect geothermal wells in a predictable manner.Geothermal energy has a lot of promise as a renewable energy source that is not dependent on the sun shining or the wind blowing, but it has some challenges to wide adoption.