The topic was taken from Chapter 5 in Prof. Susskind's book, The Black Hole War. Prof. Susskind pointed out that once Planck converted the unit such as length, time and mass from the Metric Standard to Planck Standard that allow the Universal constants which are light's speed (c), Gravitational constant (G), and Planck's Constant (h), all equal to one, the resulting Planck's length, time and mass have meanings. They are the size, half-life and mass of the smallest black hole. From this fact, I felt so ignorant that I just learnt this from his book and not any classes during my undergrad years. Please enlighten me with further info on the topic.