Archive for December, 2007

27
Dec
07

Icons Piercing Space and Time

“Like the Incarnation, the icon pierces space and time, because a physical object—a piece of wood with gesso and paint and gold leaf—is shot through with God’s eternal presence.”

This from the highly recommended post here, by Susan Cushman.

01
Dec
07

Just to Clarify

secondlaw.gifBill Bryson, in A Short History of Everything, includes a section on most major fields of scientific inquiry, and makes them accessible to us amateurs. In a section on the laws of thermodynamics, here’s how Bryson clarifies each law for us (except the zeroth, which states, “If two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.”

First law:
“for a thermodynamic cycle the sum of net heat supplied to the system and the net work done by the system is equal to zero”

Bryson translation:
you can’t create energy

Second law:
“The
entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium”
Bryson translation:
a little energy is always wasted

Third law:
“As temperature approaches absolute zero, the entropy of a system approaches a constant”

Bryson translation:
you can’t reduce temperatures to absolute zero – there will always be some residual warmth

To be certain we understand how these laws came about, Bryson quotes the following from P. W. Atkins:

There are four Laws. The third of them, the Second Law, was recognized first; the first, the Zeroth Law, was formulated last; the First Law was second; the Third Law might not even be a law in the same sense as the others.

If only they’d have made it this clear when I was in school.




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