🚀 go-pugleaf

> 
> John:
>  How do you define equilibrium?
> Tim
> 
> 
	I am pretty sure that John, and most scientists here, use 
the thermodynamic definition of equilibrium.  That is, there can never be 
any transfer of energy, in the form of either heat or work, between the 
two systems at equilibrium, not can a small perturbation start such a 
transfer.  The total entropy in the two systems can't increase.
	To quantitatively spell it out, assume two systems.  They 
are the matter comprising a living thing, and its immediate environment.

1)	There can not be any transfer of heat, sometimes called entropy,
between two systems.
	At equilibrium, the two systems must have the same temperature 
by definition.  If the living thing is at a different temperature  
as its surroundings, it is not at equilibrium.  False for most living 
mammals, sometimes true for living cold blooded animals.  A small 
change in temperature can not cause this system to start transfering 
energy.  Let the transfer of heat be dQ.
	E.G., Living things don't really follow this rule while alive.  
All of them, while active, are at a different temperature 
than their surroundings including "cold blooded" animals.  And all respond 
to changes in temperature.  They give off energy as heat.

2)	Work is energy transfered by noticeable changes in a systems 
form or composition, other than temperature.  E.G., Living things
obviouslydon't follow this, either.  They move, and change the 
composition of everything they eat.  They give off energy as work.  

3)	At equilibrium, the entropy of a system can't change.  
The change in entropy is dS = dQ/T.  
	Living things don't obey this, either.  Animals eat plants to 
decrease entropy, but make the plants increase entropy (by
respiration).  Plants decrease entropy by growing, but increase the 
entropy of sunlight by absorbing it.  There is never a decrease in 
entropy.  When a plant absorbs sunlight, the sunlight is changed 
to a higher entropy (increase entropy) and turns the carbon dioxide 
into plant (decrease entropy).  Because the temperature of the sun 
is high, heat energy from sunlight has a VERY low entropy.  Because a
plant or animal is at a low temperature, the same amount of heat energy 
in a living thing has a very  high entropy.

The total entropy: 

dQ(sunlight to infrared light)/T + dQ(carbon dioxide to plant)/T > 0.

	Living things increase entropy either by breaking down 
plant material or by turning sunlight into lower temperature heat.
I have plugged in numbers, and they work.