Does life violate the 2nd law of thermodynamics?

  • Thread starter twain
  • Start date
  • #1
36
0
If you look at earth 3000 years ago versus the earth today there is now far more structure, ie cities, roads etc. It is less random, it has less entropy, and that is as a result of life. Especially intelligent life.

Considering the solar system as a whole, does the decrease in entropy associated with earth's structures mean the 2nd law of thermodynamics is violated in this system?
 

Answers and Replies

  • #2
russ_watters
Mentor
19,878
6,297
No, that is just a fallacy purposely spread by the Young Earth Creationist crowd. All of the entropy reduced by the generation of life on earth is just a drop in the vast ocean of entropy generated by the 'burning' of the sun.
 
  • #3
phyzguy
Science Advisor
4,620
1,573
Absolutely not. Any decrease in entropy associated with living things (including human-made structures), is more than compensated by an increase in entropy of the energy source which makes life on Earth possible; i.e., the Sun. As the sun burns its nuclear fuel and emits radiation, it runs "downhill", and its entropy increases significantly
 
  • #4
36
0
Does this mean the sun is more random now than 3000 years ago? I thought the sun only loses mass with time.
 
  • #5
The law of entropy only applies to a closed system, which the Earth is not. We have energy input from the sun, which powers photosynthesis in plants, allowing them to build and store nutrients that humans consume, fueling our engineering endeavors. So a decrease in usable energy in the sun turns into an increase in usable energy here (in the plants), and ultimately, humans do use this energy.

As far as the bigger picture is concerned, though, the existence of life at all would violate thermodynamics for two reasons if atheism were true. First, it would mean the universe is a closed system, and the universe is supposed to have started as hot plasma - one of the most chaotic systems known. Fast forward several billion years, and we now have incredible structures like the human brain, which Isaac Asimov called "the most complex and orderly arrangement of matter in the universe." With no input from an agent outside the universe, the increase in order would certainly be a violation of the second law.

And second, order doesn't just increase with an addition of energy. The addition itself must be orderly. If you add chaotic energy, you actually increase the chaos of the system. A good example is a puzzle. Suppose you open a puzzle box and empty its pieces on to a table. The puzzle begins in a state of chaos; the goal of the puzzle is to put its pieces into a state of order. That cannot be done by adding random energy. If you sat some monkeys down at the table, they'd start throwing the pieces around - energy is being expended, but the order not increasing. You must apply orderly energy to increase a system's order. So the origin of DNA, cells, and complex life in the first place could not be achieved just be giving the earth energy from the sun or other random sources like lightning strikes.
 
  • #6
russ_watters
Mentor
19,878
6,297
Does this mean the sun is more random now than 3000 years ago? I thought the sun only loses mass with time.
Well, no. Entropy is lost via the energy radiated into space. As said, it's an open system.
 
  • #7
36
0
Can't we consider the earth plus the sun plus the rest of the solar system a closed system? If nothing else existed, would this universe be a closed system?
 
  • #8
russ_watters
Mentor
19,878
6,297
Can't we consider the earth plus the sun plus the rest of the solar system a closed system? If nothing else existed, would this universe be a closed system?
The sun's radiation travels past the limits of the solar system, but if this was all there is, then yes, you could consider it a closed system. This wouldn't change the answer.

Lets keep the religious discussion out of this: this is a science forum.
 
  • #9
Lets keep the religious discussion out of this: this is a science forum.
I think you were the first one to mention the Young Earth Creation crowd ...
 
  • #10
36
0
If the temperature distribution of the solar system is constant in the long term, which it probably is, its entropy is constant. Except from the structures on earth. So it is crucial what happens to energy emitted to space. If it traveled forever without ever hitting anything, the entire system would have a constant temperature and entropy. Except those cities on earth.
 
Last edited:
  • #11
russ_watters
Mentor
19,878
6,297
I think you were the first one to mention the Young Earth Creation crowd ...
Stating the origin of the argument is not a discussion of religion. And my post was not a suggestion. Religious discussion is not allowed here.
 
  • #12
russ_watters
Mentor
19,878
6,297
....the entire system would have a constant temperature and entropy.
Neither of those is true. The sun is continuously generating entropy and its fuel does not last forever.
 
  • #13
36
0
I'm getting confused now. Is the sun in a constant state or getting more and more random?
 
  • #14
phyzguy
Science Advisor
4,620
1,573
As the sun emits radiation, the entropy of the universe increases. The entropy of radiation is approximately equal to the number of photons in the radiation. The sun has emitted an enormous number of photons during its life (something like 10^65, if I calculated correctly). The entropy of the universe has increased significantly due to the emission of this radiation, far more than the decrease in entropy represented by living things on Earth.
 
  • #15
479
32
The heat generated by the building of those structures and working the materials increases the total entropy of the system.
 
  • #16
ZapperZ
Staff Emeritus
Science Advisor
Education Advisor
Insights Author
35,847
4,664
If you look at earth 3000 years ago versus the earth today there is now far more structure, ie cities, roads etc. It is less random, it has less entropy, and that is as a result of life. Especially intelligent life.

Considering the solar system as a whole, does the decrease in entropy associated with earth's structures mean the 2nd law of thermodynamics is violated in this system?
Please read:

http://arxiv.org/abs/1003.3937
D. Styer, Am. J. Phys. v.76, 1031 (2008).
http://arxiv.org/abs/0903.4603
http://www.physorg.com/news137679868.html

Zz.
 
  • #17
36
0
The entropy of the universe has increased significantly due to the emission of this radiation, far more than the decrease in entropy represented by living things on Earth.
So even empty space has entropy then, not just matter? And at the time the 2nd law was stated, people included e/m waves in their thinking so even empty space had entropy for them?
 
  • #18
36
0
Thanks ZapperZ. I wonder if evolution is really the same as far as the 2nd law is concerned as intelligent life taking conscious action. The latter must be many orders of magnitude faster. Most urban structure appeared in the last 50-100 years.
 
Last edited:
  • #20
phyzguy
Science Advisor
4,620
1,573
So even empty space has entropy then, not just matter? And at the time the 2nd law was stated, people included e/m waves in their thinking so even empty space had entropy for them?
It is not "empty space" that carries the entropy, it is the photons. If the space includes photons, it is not empty.
 
  • #21
russ_watters
Mentor
19,878
6,297
So even empty space has entropy then, not just matter? And at the time the 2nd law was stated, people included e/m waves in their thinking so even empty space had entropy for them?
Entropy is energy, so yes, energy doesn't have to be associated with matter.
 
  • #22
36
0
What about energy in the form of low frequency radio waves, does this have entropy?

If yes, is this entropy independent of the shape of the radio waves and only dependent on the number of quanta?

Is there some formula defining the entropy of any arbitrary 3D wave pattern?
 
  • #23
russ_watters
Mentor
19,878
6,297
What about energy in the form of low frequency radio waves, does this have entropy?
All em radiation carries entropy.
If yes, is this entropy independent of the shape of the radio waves and only dependent on the number of quanta?
The amount of energy - and therefore entropy - is frequency dependent.
Is there some formula defining the entropy of any arbitrary 3D wave pattern?
What's a "3d wave pattern" and what does this have to do with the thread?
 
  • #24
96
0
If you look at earth 3000 years ago versus the earth today there is now far more structure, ie cities, roads etc. It is less random, it has less entropy, and that is as a result of life. Especially intelligent life.

Considering the solar system as a whole, does the decrease in entropy associated with earth's structures mean the 2nd law of thermodynamics is violated in this system?
You really think a building or a road has more order than the nature it replaced? A cell is something incredibly complex and structured compared to a heap of stones, no matter how orderly arranged. One problem is that you're using subjective everyday words like "order" and "disorder" to describe things around us. A city may seem more orderly than a forest to you, but that is highly subjective. In order to describe "order" in a physical sense, you'll have to attend to invisible forms of "order" and "disorder" as well, like the heat radiation emanating from virtually everything. Your brain may think orderly thoughts, but while doing so it emanates heat radiation contributing to the increase of entropy in the universe.

I don't think any example has been found of the 2nd law of thermodynamics being violated.
 
  • #25
36
0
The amount of energy - and therefore entropy - is frequency dependent.
So it's the same energy no matter what the amplitude? ;) I thought entropy is a measure of disorder, not a measure of energy.

What's a "3d wave pattern" and what does this have to do with the thread?
Never seen one? Let's stick to 2D then, like water waves in a pond. They can be ordered, or they can be noisy. As can e/m waves. I want to know how their entropy is defined as an equation in terms of the wave forms. It can't be just energy.

What does this have to do with intelligent life violating the 2nd law: it's an attempt to define entropy for e/m waves, as they leave the sun and fill the universe. "Entropy = number of photons" seems inappropriate for radio waves.
 
Last edited:

Related Threads on Does life violate the 2nd law of thermodynamics?

Replies
18
Views
7K
Replies
7
Views
4K
Replies
6
Views
3K
Replies
10
Views
2K
Replies
9
Views
3K
Replies
18
Views
4K
Replies
4
Views
4K
Replies
2
Views
2K
Replies
1
Views
1K
Replies
9
Views
2K
Top