I am working my way through the “The Theoretical Minimum”, a recently published book written by Leonard Susskind of Stanford University and George Hrabovsky of Madison Area Science and Technology (MAST). So far it seems that the book is a great refresher on classical mechanics.
In particular, a famous quote from Pierre-Simon Laplace is provided near the beginning of the first chapter and this got me thinking:
“We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.”
Susskind and Hrabovsky further elaborate:
“In classical physics, if you know everything about a system at some instant of time, and you know the equations that govern how the system changes, then you can predict the future. That’s what we mean when we say that the classical laws of physics are deterministic. If we can say the same thing, but with past and future reversed, then the same equations tell you everything about the past. Such a system is called reversible.”
While the above observations can be applied to the consideration of almost all aspects of geology and engineering one way or another, I am particularly interested in how they can be applied to engineering rock mechanics. Adapting the text from a later part of Susskind’s book, it is clear that to perfectly model the way in which a rock mass would behave when affected by engineering works requires:
1) A perfect knowledge of the dynamical laws governing the rock mass.
2) Tremendous computing power.
3) The ability to know the initial conditions with almost perfect precision.
Obviously, these conditions do not exist in practice. However, I wonder how far away we are? My initial thoughts with regards to the three points above are:
1) This aspect is primarily related to the theory of engineering rock mechanics and it seems we are a very long way away from a perfect knowledge. While many advances occurred in the second half of the 20th Century, it now seems that further progress is glacial. I believe that this is largely because of the intellectual and “legislative” conservatism of the civil engineering and mining industries combined with the impact of empirical systems such as NGI-Q and RMR. The combination of these factors have basically halted progress towards a deeper theoretical understanding of engineering rock mechanics (or have at least halted the practical application of new theories). Improvements could be made by increasing funding for fundamental rock mechanics research, which is largely non-existent at present. While much of the funding should come from government sources, industry really needs to grasp the nettle as well. Funding should be dependent on researchers building up a very robust evidence base (essential to overcoming the huge conservatism hurdle in engineering) and developing and disseminating the practical applications of the research via industry publications and direct presentation to students and influential practitioners. The starting point and main thrust of the research should focus on new frontiers and not incremental improvements of existing systems – leave the small tweaks to industry.
2) Thanks to Moore’s Law, it seems that the need for tremendous computing power is not a problem. In any case, the problems related to points 1 and 3 in engineering rock mechanics are so great that this appears to be the least important point at the moment. Consequently, I do not believe there is any pressing need for improvement in computing power with respect to engineering rock mechanics until significant progress has been made on points 1 and 2.
3) This aspect is primarily related to engineering geology. Unfortunately, it does not seem likely that we will ever know the starting conditions with perfect precision, given that so much of the rock mechanics system is not accessible for assessment. However, this is frequently used as an excuse to pay lip-service to this aspect. Many (most?) “engineering geological” assessments are woeful in their execution. There are a multitude of reasons for this including incompetence, lack of money and lack of time. However, fundamentally it seems that second-rate engineering geological work is generally considered to be acceptable in mining and civil engineering. This could be improved by getting a competent engineering geologist to direct the assessment and giving them the money and time they need to do it properly.
Interestingly, the engineering industry seems to behave as if points 1 and 3 are largely resolved and that the main opportunities for improvements are in computing power and software. Clients are regularly presented with the findings of computer models based on poor engineering geological work, misapplied empirical rock mass classification schemes and old theories. Needless to say such findings can be incredibly problematic. The cart is firmly before the horse.
Anyway, these are my initial views on a huge topic. However, I am much more interested in what you think. How far away do you think we are from the Holy Grail? How could we improve things? Who has the required time, money and knowledge?
© Christopher Jack