The Fall of Jericho: From an Engineer's Perpective

Introduction

I am not trying to discredit here the miracle that was accounted in the book of Joshua.
On the contrary, what im trying to say is that it is not impossible to happen. Many bible critics may claim that that incident described in Joshua 6 is a pure folklore, exagerated by time as it is passed from mouth to mouth. I highly disagree on this. As an engineer I know that what happened then is true and can be explained by science. The miracle is not that the walls of Jericho fell. The miracle is more on how such people of primitive knowledge of theory of resonance and wave physics made the walls collapse. The answer of course is given by the Bible: they were instructed by God.

The Account of the Fall of Jericho

Here is the complete account as written by Joshua:

Joshua 6 (New International Version)

Joshua 6
1 Now Jericho was tightly shut up because of the Israelites. No one went out and no one came in. 

2 Then the LORD said to Joshua, "See, I have delivered Jericho into your hands, along with its king and its fighting men. 3 March around the city once with all the armed men. Do this for six days. 4 Have seven priests carry trumpets of rams' horns in front of the ark. On the seventh day, march around the city seven times, with the priests blowing the trumpets. 5 When you hear them sound a long blast on the trumpets, have all the people give a loud shout; then the wall of the city will collapse and the people will go up, every man straight in." 

6 So Joshua son of Nun called the priests and said to them, "Take up the ark of the covenant of the LORD and have seven priests carry trumpets in front of it." 7 And he ordered the people, "Advance! March around the city, with the armed guard going ahead of the ark of the LORD." 

8 When Joshua had spoken to the people, the seven priests carrying the seven trumpets before the LORD went forward, blowing their trumpets, and the ark of the LORD's covenant followed them. 9 The armed guard marched ahead of the priests who blew the trumpets, and the rear guard followed the ark. All this time the trumpets were sounding. 10 But Joshua had commanded the people, "Do not give a war cry, do not raise your voices, do not say a word until the day I tell you to shout. Then shout!" 11 So he had the ark of the LORD carried around the city, circling it once. Then the people returned to camp and spent the night there. 

12 Joshua got up early the next morning and the priests took up the ark of the LORD. 13 The seven priests carrying the seven trumpets went forward, marching before the ark of the LORD and blowing the trumpets. The armed men went ahead of them and the rear guard followed the ark of the LORD, while the trumpets kept sounding. 14 So on the second day they marched around the city once and returned to the camp. They did this for six days. 

15 On the seventh day, they got up at daybreak and marched around the city seven times in the same manner, except that on that day they circled the city seven times. 16 The seventh time around, when the priests sounded the trumpet blast, Joshua commanded the people, "Shout! For the LORD has given you the city! 17 The city and all that is in it are to be devoted [a] to the LORD. Only Rahab the prostitute [b] and all who are with her in her house shall be spared, because she hid the spies we sent. 18 But keep away from the devoted things, so that you will not bring about your own destruction by taking any of them. Otherwise you will make the camp of Israel liable to destruction and bring trouble on it. 19 All the silver and gold and the articles of bronze and iron are sacred to the LORD and must go into his treasury." 

20 When the trumpets sounded, the people shouted, and at the sound of the trumpet, when the people gave a loud shout, the wall collapsed; so every man charged straight in, and they took the city. 
(Source:http://www.biblegateway.com/passage/?search=joshua%206&version=31)

Observations

To a careful observer, the details matter. What Joshua and the rest of the soldiers did is to march around the walls. They had a trumpet sounding in front of them so it makes sense to assume that their steps are in cadence. They did this for six days. On the seventh day they repeated the march and went around the walls seven times. Now according to Numbers 1:46, there were 603,550 men who were fit for military service. Now imagine more than half a million men marching in cadence. The march would sure to produce vibration enough to shake the ground.
Now it doesnt't end there. At the end of the seventh march, they all (more than half a million men) gave a loud and accordant shout. Then finally they had the trumpets blow a ONE LONG NOTE. Then that made the walls fall.
Now the question is that is this even possible? How can a march and a shout, and a one long note can make the strongest walls of the ancient eastern world fall? The answer is physics. It is an application of the mechanics of waves and the concept of resonance. It do happen even in the modern world.

Let me explain further by appealing to the experts. This is a qoute from the website of the Physics Department of the Univeristy of Wisconsin-Stout

"When troopers march in cadence across a bridge, the marching may match a natural resonance frequency of the bridge. Although only a small amount of energy is added with each step, because of the resonance effect this energy will be stored. As a result, the bridge will cumulatively absorb energy from the marching men, increasing the oscillation amplitude in the bridge (just as pushing someone on a swing, in cadence, increase the amplitude of the swing). Enough energy may be added this way to damage or destroy the bridge. In fact, a concrete suspension bridge, the Tacoma Narrows Bridge, was destroyed by resonance vibrations set up by winds acting on the bridge. Today's bridges are constructed to prevent or minimize this type of wind resonance effects." (Source:http://physics.uwstout.edu/deptpages/physqz/resonanc.htm#Answer_)

Now did Joshua knew this all along? I doubt. Modern world did not even knew until April 16, 1850 (see http://en.wikipedia.org/wiki/Angers_Bridge). It was God who told Joshua, and he did just as he was told, though most probably he does not understand the logic.

Now why need to march for 6 days, can't it be done by just marching 7 times in 1 day? Well im not sure of the real reason, but based on my understanding of God's character, the reason may be psychological. Maybe He was trying to give time for the people of Jericho to choose if they want to get out and join the Israelites, or to stay inside and test God's power. God will sure to accept anyone who will believe in Him. Rahab the prostitute will testify to that. But whatever God's reason behind the six days, it sure did strengthened the faith of the Israelites. Imagine the tension caused by the anticipation of what is going to happen. Im sure they had thier doubts, and God drove the doubt to the max before finally shattering it to dust. I do really appreciate the science, and the infinite wisdom behind this story. And the message is eternal: Do not test what God can do. Do not wait for the last day, go to him now and be saved from the collapsing walls of your own world. We all have our six days. No need to wait for the seventh. Besides, we can't really count the days, can we?