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Reply #179: I'm not the one sidestepping -- Bazant is. [View All]

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eomer Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Nov-11-09 07:34 AM
Response to Reply #175
179. I'm not the one sidestepping -- Bazant is.
What he sidesteps is the distribution over time of the application of that "critical energy".

If I am traveling down the highway at 100 MPH then my car has enough kinetic energy to tear my tires to shreds, but only if that "critical energy" could somehow be applied to my tires all at once. If on the other hand the application of that energy to my tires is distributed over time then they will not be shredded. Luckily for me the complex system consisting of my car and the road is incapable of delivering all that energy to my tires at a single instant. No matter how I drive the car the application of the energy to my tires is going to get distributed over time and they are likely not going to get shredded. The energy is "critical" only in theory.

Bazant takes all the kinetic energy that exists at time of impact of C against A, which is all in C (B does not yet exist), and assumes that all of that energy is applied against A at a single instant. But C is incapable of applying all that kinetic energy at a single instant. The actual distribution over time of the application of that energy against A is going to be drastically different than Bazant's magical "all in a single instant".

So I am not ignoring that the "critical energy" exists, I'm just not conceding Bazant's conclusion that it is critical. It is critical if you make an assumption that goes magical and abandons the application of the laws of physics. But if you consider the question in the real world where the laws of physics insist on being followed, we don't know the answer yet because no one has worked through it.

And the fact that the model more or less matches the fall time is clearly due to Bazant backing into a model that makes it so. It proves nothing other than how modeling works.

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