Why was it so easy for Alexander to find recruits

Explanation:

The tactics of the Sarissa Phalanx holding the line while cavalry and mobile infantry flanked and routed the enemy is why Alexander was so successful. It worked against every enemy of that era.  The phalanx, the sarissa along with the tactics used all undoubtedly contributed to the success of Alexander's army.

studies show tha in 7.5 billion years from now, the expanding sun will engulf, and destroy, the earth.