thermodynamics question

Casey · 11-25-2005, 04:43 PM

Something that my prof posted but I have no idea. Anyone else?

The Second Law of Thermodynamics states that entropy (disorganization) tends to increase with time. Living organisms tend to become more complex with time (embryos grow into complex adults, populations of species evolve). Yet, the law is still valid. How can this be?
Discuss.

cuziamthecaptai · 11-25-2005, 05:23 PM

Quote:

Originally Posted by Casey

Something that my prof posted but I have no idea. Anyone else?

The Second Law of Thermodynamics states that entropy (disorganization) tends to increase with time. Living organisms tend to become more complex with time (embryos grow into complex adults, populations of species evolve). Yet, the law is still valid. How can this be?
Discuss.

The 2nd law of thermodynamics, in full, is:
"The total entropy of any isolated thermodynamic system tends to increase over time, approaching a maximum value." Therein, lies your answer.

Living organisms aren't isolated systems. Animal populations can evolve because they consume energy, which offsets the tendency towards entropy.

JerryLove · 11-25-2005, 05:36 PM

In taking potential energy, and consuming (dispersing) it; life only serves to further overall entropy (as does every process).

la_meteo · 11-28-2005, 08:30 AM

Thanks for the answers, and I totally understand now, but is there a way to go more in depth on this topic? I mean, the statements you gave seem to fully answer the question.

JerryLove · 11-28-2005, 11:48 AM

I'm not sure what you are asking for.

la_meteo · 11-28-2005, 11:53 AM

ah.. nevermind. I have what I was looking for, thanks again.

Casey · 12-01-2005, 10:09 AM

Cuzi and Jerry, your answers seem to conflict sort of. How do you define "isolated system." Cuzi is making the point that an organism or even a population is not an isolated system while Jerry seems to be saying, "The World as an isolated system... ."

Qingu · 12-01-2005, 10:26 AM

The world isn't an isolated system. There is a constant influx of energy from the sun.

JerryLove · 12-01-2005, 10:39 AM

Quote:

Cuzi and Jerry, your answers seem to conflict sort of. How do you define "isolated system." Cuzi is making the point that an organism or even a population is not an isolated system while Jerry seems to be saying, "The World as an isolated system... ."

The world is not an isolated system. An isolated system is one which neither influences nor is influenced by anything outside it. The universe *may* be an isolated system.

rheo · 12-08-2005, 08:57 PM

So, if there is *no* isolated system, how does this law ever come into effect?

SccHarpGirl · 12-08-2005, 09:16 PM

Quote:

Originally Posted by rheo

So, if there is *no* isolated system, how does this law ever come into effect?

most scientific laws are based on ideal systems that cannot be ever truly found in nature, but can only be set up in a lab. These ideals are used as a method to try and explain what is observed in the world around. Observing and basing laws on non-ideal systems creates many, many complications which can be vastly simplified by using ideal models.

I remember studying this last year, how a system can decrease in entropy but the surrounding system increases in entropy.

JerryLove · 12-09-2005, 07:23 AM

Quote:

So, if there is *no* isolated system, how does this law ever come into effect?

Factor out the influx/outpath of energy.

JerryLove · 12-09-2005, 07:24 AM

Quote:

I remember studying this last year, how a system can decrease in entropy but the surrounding system increases in entropy.

Sure, a refridgerator is a good example.

nate95366 · 12-12-2005, 02:10 PM

I find that when studying entropy, you've got to ask yourself when you see a system apparently becoming "more organized" (not sure I like the term "organized" to describe a system's entropy characteristics, but that's another time and place), what else in the universe might be increasing in entropy, and by what amount? It takes the "disorganization" of many other things to make sure that a living body stays relatively organized. Overall, the net effect tends toward the entropy of the universe as whole.

Nate