Thursday, August 25, 2011

2nd Law of Thermodynamics

The Second Law of Thermodynamics states the following:
  • It is impossible to turn all of the heat put into a system into work so that you can’t make a 100% efficient engine.
  • The amount of unusable energy in a closed system increases.
  • The entropy in a closed system always increases.

The basic concept behind the 2nd law of Thermodynamics is the fact that heat always spontaneously flows from hot objects to colder objects. It never spontaneously flows from cold objects to hot objects.

When heat transfer is being used to do work some of the heat always goes to the colder location. This wasted heat is called entropy. Simply put you can never turn all of the heat into work.

Now heat can be forced to go from a cold object to a hot object by applying work, which also reduces entropy, thus showing that work can reduce entropy. This process is the bases of air conditioners, refrigerators, and heat pumps.

Entropy is the measure of a system's thermal energy unavailable for conversion into mechanical work. It is also a measure of the equivalent states or multiplicity of a system and there by a measure of the disorder or randomness in a system.

In Classical Thermodynamics entropy is mathematically defined as dS = dQ/T.

These results in the change in entropy as: DS = Q/T.

  • S = entropy
  • Q = Heat energy
  • T = Temperature

In statically thermodynamics entropy is mathematically defined as S = k ln W.

This results in the change in entropy as: DS = k ln W2 / W1.

  •  S = entropy
  •  k = Boltzmann constant
  •  W = the multiplicity of a system.

Entropy and Disorder

Entropy is related to disorder through multiplicity of a system denoted by W. The multiplicity of disordered states (Wd) is far more than the multiplicity of ordered states (Wo) such that Wd >> Wo  this means they Sd >> So.

Since 2nd Law of Thermodynamics indicates that entropy tends to increase it also indicates that a system’s degree of disorder tends to increases. The only way to increase a system’s order and there by decrease its entropy; is to do work on the system.

Abiogenesis and 2nd Law

Abiogenesis is life spontaneously being formed from non life by naturalistic means. However living things are the most ordered and complex systems known to exist, and the simplest known living cell is infinitely more organized and complex than the most organized non-living chemical systems produced in a lab

This means that the entropy of a living cell is many orders of magnitude lower than the entropy of the same amount non-living chemicals. This means that abiogenesis goes against the 2nd law’s tendency towards increasing entropy.

While entropy can be decreased by applying work to a system no evidence exists for a naturalistic mechanism for such a large decrease in entropy. Without this mechanism the 2nd law suggests that abiogenesis is impossible.

Applied Energy and 2nd Law

While the 2nd Law shows that energy applied a system can reduce its entropy, it does not show how the manner in which energy is applied to a system affects entropy.  It does not show the deference between construction work and a bomb.

Construction work reduces a system’s entropy while bombs increase a system’s entropy.  Unfortunately the 2nd Law does not show the difference.  So an additional principle is needed to show this difference and it is also need to really determine if abiogenesis is possible or not.

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