Our post title is a play on the popular term GPS—Global Positioning System. Summer is the active season for vacations and family reunions, sometimes in distant locales. Travel by automobile is not nearly the same challenge as decades ago. One travel accessory was the inevitable set of roadmaps and Trip-tiks. In our day many still feel secure with old fashioned folded road maps. These travel aids are still useful for supplying automobile occupants with the big picture of where they are going, how long the trip will take, and other calculable details. But the traditional reliable printed guides have been replaced by GPS screens on the dashboard. Even better, GPS I-phone apps provide incredible capabilities.
In 1978 our military launched their first GPS satellite powered mainly by solar energy. Currently there are 24 GPS satellites orbiting 11,000 nautical miles above earth. Each satellite orbits the earth at 18,000 mph. In order to pinpoint a precise three-dimensional spot on earth to 15 meter or better accuracy we must know the accurate, instantaneous distance to four different orbiting satellites.
The exact distance between the GPS satellite and the GPS receiver on the ground must be calculated. From 11,000 nautical miles a microwave signal travels between the GPS receiver and the satellite it is tracking. The microwave signal takes about 0.06 seconds to travel this distance. Microwaves travel at the known speed of light. The distance between the GPS satellite and the GPS receiver on the ground may then be calculated by multiplying the exact time taken for the signal to reach the ground times the speed of light, known to be 186,000 miles per sec. This supplies the distance between the two devices. Geometrical calculations take over in a process called trilateration.
The I-phone screen reveals its wonders each second of highway travel. A portion of the landscape, complete with in-scale graphics of local streets, roads, parks, and water bodies, scrolls down the screen along with a symbol of your vehicle moving forward along the highway at speeds matching your real speed. Each position of your vehicle on the screen represents your instantaneous position as calculated by the trilateration described above. Positioning information is renewed many times per second. In addition to display of instantaneous ground position, movement, speed, and projected arrival times, GPS technology has applications to agriculture, reconnaissance, guided missiles, emergency response, and many others.
Our omniscient God is aware of all physical locations in the universe at each moment. In addition, he knows the spiritual location of all humans. We must search for our spiritual location. God provides accessibility to himself. “God did this so that they would seek him and perhaps reach out for him and find him, though he is not far from any one of us. For in him we live and move and have our being…” Acts 17:27-28 (NIV).
In terms of our physical location modern humans now have instant access to this information. Through the wonders of the electromagnetic spectrum an unlimited array of different wavelengths is able to transfer energy and information from distant places at the speed of light. Through modern technology we have learned to harness electromagnetic energy such as microwaves and blend other scientific discoveries to produce the full scope benefits of our GPS devices. Alexander Graham Bell’s initial invention of the telegraph was demonstrated in 1844 in a light speed communication between Washington and Baltimore. The coded message was “What hath God wrought?” That message still remains appropriate today with increasing frequency.
