Paper Review - "Reality Based Interaction: A Framework for Post-WIMP Interfaces"

From the early days of the Command-Line to the present Window Icon Menu Pointing device (WIMP) much has changed, and still changes quickly. It seems the more technology evolves the quicker new interfacing systems are invented.
More recently we've seen the boom of the touch-screen, which has revolutionised the way we interact with our electronic gadgets by allowing us to perform actions in a much more simple and intuitive way.

Proposed in the paper is yet a new way to interact with our gadgets: Reality Based Interaction (RBI). Based on 4 key principles, RBI's goal is to bring reality to our everyday interactions with our gadgets like never before.

RBI's first principle is Naïve Physics (NP); the common sense knowledge humans have about the physical world. Physics attributes such as mass and gravity are simulated on interfaces to give a more real feel, e.g. when scrolling through the phonebook on an iPhone or Android device.

The second principle, Body Awareness and Skills (BAS), refers to the familiarity and understanding that people have of their own bodies. Using our limbs to interact with interfaces adds even greater reality as humans interact with real objects on a daily-basis.

Environment Awareness and Skills (EAS) deals with the clues the environment gives us about what surrounds us and how to navigate it.
The last principle, Social Awareness and Skills (SAS), include humans' ability to communicate verbally and non-verbally, exchange objects and work with others on a task. Here's an example:

Adding realism to an interface doesn't always pay off though, trade-offs need to be made between reality and the RBI's principles in order to produce an effective product.
A good point made by the authors is that reality should be given up only when other desired qualities such as expressive power, efficiency, versatility, ergonomics, accessibility and practicality are gained.

In conclusion, the material in the paper is certainly exciting and interesting but no concept or theory of the implementation of such methods is mentioned, which makes it feel "hand-wavy" (pun intended).