Even if I am very wrong here on that point and the radiation pushes them all in the same initial direction what happens to that motion the first time they collide with something? Drop the box of ping pong balls straight down onto the ground, They all initialy go the same direction (towards the floor) but when they hit something they go all over the place. The same thing would happen as the orintation of each molecule will be different when they hit eachother. O=C=O The molecule will be spinning on its own axis, would you not agree that different orinentations would produce different results if they collided with something in the same direction? Drop a pencil 10x head on, 10x flat, and 10x slanted and see for yourself it goes the same way each time.