As a Christian scientist, Dr. Bohlin is open to examining the theories of both young-earth and old-earth scientists to explain what we can observe today. The Grand Canyon provides an excellent venue to consider the theories of both groups on how the geological layers were formed and when this occured.
If the door is already attached, swing it open and closed to see how much inertia it has. An average hollow-core door usually weighs around 25 to 30 pounds, so if you can lift or swing the door with minimal effort, it is probably hollow-core. Solid-core doors are usually 25 to 30 pounds heavier than their hollow counterparts, so if the door has some heft to it, it's probably solid-core.
The cost of a hollow-core door costs as low as $30. Constructing or repairing a door frame can add an additional $300-$700 to your cost, depending on the door location and the work required. If you need an old door removed, plan to add $100 for removal and disposal costs.