The Notions of Feasibility and Np-hardness: Brief Introduction

For example, if for some input x of length len(x) = n, an algorithm requires 2 computational steps, then for an input of a reasonable length n ≈ 300, we would need 2 computational steps. Even if we use a hypothetical computer for which each step takes the smallest physically possible time (the time during which light passes through the smallest known elementary particle), we would still need more computational steps than can be performed during the (approximately 20 billion years) lifetime of our Universe.