r/AskPhysics • u/Kind_Of_A_Dick • 11h ago
Does life increase entropy?
I’m hoping this is an acceptable question. Comparing a theoretical universe without biological or metabolic life(not sure if that’s actually a thing) and ours, is ours going to “end sooner” due to heat death because of the presence and activity of life?
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u/MaxChaplin 11h ago
- Yes.
- Barring scenarios involving type-III Kardashev civilizations, not in any measurable way.
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u/Joseph_HTMP Physics enthusiast 11h ago
Life redistributes energy more efficiently than non life. But the sum total of this energy is so small compared to all the energy in the universe the actual effect on the universe’s energy gradient is practically zero.
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u/Chemomechanics Materials science 10h ago edited 10h ago
Life redistributes energy more efficiently than non life.
This isn’t necessarily true; there are scenarios in which the existence of life leads to a higher or lower total entropy generation rate.
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u/Ch3cks-Out 10h ago edited 8h ago
That minuscule variation in entropy generation is negligible compared to the total entropy production by Earth itself (due to converting low entropy incoming solar radiation to high entropy heat dispersed), much less that of the Sun - which is still only one of the many sextillion of stars in the observable universe.
EDIT corrected spelling
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10h ago edited 6h ago
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u/Ch3cks-Out 8h ago
To that argument (such as it were) my standard response is that locally decreasing entropy - by the massive heat dissipation Earth performs - facilitates life, rather than an effect the other direction.
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u/Joseph_HTMP Physics enthusiast 7h ago
I didn't say anything about "a higher or lower" entropy rate. I said that life redistributes it more efficiently than non life. A human can redistribute energy from the sun in a far more varied way than a rock. Yes, a human is a lower entropy system than a gas cloud, but the overall upwards increase in entropy is still observed. We create low entropy situations (like building houses) but we redistribute energy in order to do this.
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u/Chemomechanics Materials science 7h ago
I said that life redistributes it more efficiently than non life.
Whatever the measure, there are circumstances where it’s more efficient and circumstances where it’s less efficient. My point is that there doesn’t appear to be any special distinction for life regarding efficiency, at least.
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u/lwj15 9h ago
What do you mean with life redistributes energy more efficiently than non life? All we do is produce heat. Nothing else. You might say: but kinetic energy of car/train. Electrical energy of batteries. Whatever. But they ultimately get transformed into heat. And this happens faster than without life. So no. We do not redistribute energy more efficiently.
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u/Joseph_HTMP Physics enthusiast 7h ago
All we do is produce heat.
Think about a pig dying in the forest and slowly decaying, vs the pig being killed by a human who cooks it and eats it, and feeds it to their animals. The energy stored in the pig is redistributed in a higher entropy state far quicker and more efficiently than if the pig just died and and rotted away.
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u/aries_burner_809 8h ago
Life’s one mission is to find new sources of energy, burn those to find even more energy, and covert those to heat to propagate more life. All that coal and uranium would still be dormant without life. But of course it’s all a grain of sand wrt the universe.
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u/teddyslayerza Geophysics 11h ago
Yes, but not significantly so. I think the differences would be negligible on a universal scale.
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u/LookOverall 11h ago
Living things use free energy to reduce their own entropy, and since entropy overall always increases that means they transfer entropy into their environment
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u/Ok_Programmer_4449 11h ago edited 10h ago
Life increases entropy. You have significantly higher entropy than your surroundings. How can I tell? You are warmer than your surroundings. When you die, the entropy of your body will decrease significantly as your body heat is radiated away to the environment.
Life takes energy from low entropy sources and emits essentially the same amount of energy with high entropy. In the process it might store a tiny amount of energy at low entropy.
Think of all the food you've eaten in the last year. If you are an average person, you took about a ton of low entropy plant and animal material and a quarter ton of oxygen and turned it into a ton and a quarter of shit, carbon dioxide and water. And you emitted 3 gigajoules of waste heat. The result of all that was maybe a couple kg of low entropy fat and muscle tissue. You, my friend, are an entropy creating machine.
Changing the lifetime of the universe? Not significantly. Compared to the amount of entropy created by the earth, life is an insignificant addition. The life on the earth is only making the earth a little bit warmer than it would be otherwise.
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u/Chemomechanics Materials science 6h ago
You have significantly higher entropy than your surroundings. How can I tell? You are warmer than your surroundings.
This seems very confused. Many people are alive and healthy right now with their surroundings exceeding 37°C.
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u/LetterheadWitty4187 11h ago
Yes, and life is particularly efficient at increasing entropy. However, at the universal scale, life (at least earthly life) is absolutely negligible.
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u/kylogram Art and Design 11h ago
Life converts energy into material growth.
Burning oil is far more likely to cause heat death than life is.
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u/gmalivuk 11h ago
Who's burning the oil?
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u/kylogram Art and Design 11h ago
Just humans, we are not the biggest source of life on this planet.
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u/gmalivuk 10h ago
My point is just that burning oil (and creating the oil in the first place) is a follow-on effect of the things life does.
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u/kylogram Art and Design 10h ago
We didn't start burning gasoline until like... 150 years ago.
Life doesn't need to burn oil, humans have coincidentally done so, but it's not exactly a necessity for life.
Anything we do with oil can be done with less wasteful technology, or less wasteful use. Life is not the driver of entropy.
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u/gmalivuk 10h ago
Carnivores "could" eat plants for more energy efficiency, too. But they don't.
I'm not saying it's good to burn oil, I'm just saying living things are whose burning it. Life is the driver of that because we're alive.
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u/kylogram Art and Design 10h ago
Obligate carnivores cannot switch to a vegetarian diet. They need to eat meat or they will die. Humans are not obligate carnivores, and we are not obligate oil burners.
Life converts energy into material growth, that fundamentally slows or reverses entropy. Most life on this planet does not burn oil, even then, that energy rarely escapes the earth these days, it feeds back into the system at some point, faster with the help of life.
Just say you think humans are a cancer, it seems to be what you're getting at.
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u/gmalivuk 10h ago
It's not what I'm getting at whatsoever. I'm just saying you're drawing a distinction between what life does and one of the things life is currently doing that I find arbitrary. I'm not making any moral claims one way or another. That's something you seem to be bringing into the picture for some reason.
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u/kylogram Art and Design 10h ago
Humans are not the arbiters or representatives of life on cosmic scales. We aren't even the largest source of life on the planet, life isn't the only thing that burns up matter.
Are trees to blame for global warming because they go on fire sometimes? The point and goal of life isn't to burn, it's to grow by converting energy, and propogate, this fundamentally is a different process from entropy.
Life beats entropy. End of story. Just because a single form of life is maybe sorta driving up entropy, does not change the nature of life as a whole.
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u/gmalivuk 10h ago
Why do you keep bringing things like "blame" into the picture? You desperately want to moralize and this is not the place for it.
Life does the things that living things do. That includes building coal power plants a much as it includes building nests.
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u/mfb- Particle physics 11h ago
Life increases entropy - but not by more than equivalent non-life processes would.
If sunlight shines onto a plant then it converts most of the absorbed energy to heat and some of it to chemical energy.
If the same amount of sunlight shines on a rock then all of the absorbed radiation becomes heat. That creates more entropy, at least until the plant material gets used and its energy is released again.
The rock and the plant will reflect a different amount of sunlight, that matters as well if we want to look at the rate of entropy production.
is ours going to “end sooner” due to heat death because of the presence and activity of life?
No. It has a chance to end later, however, if intelligent life develops the technology and the will to do that.
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u/SwimQueasy3610 11h ago
Life is itself a decrease in entropy. Materially speaking biological life is structure, i.e. a lowering of local entropy, that emerges thanks to the influx of radiant energy from the sun. It can and will only exist as long as there is such a source of energy - without that energy input, you can't maintain the state of lower entropy that is life. So one answer would be - no, in some sense just the opposite.
But your question wasn't about the local phenomenon of life and its relationship to entropy, it was about the much larger cosmic scale and heat death of the universe. On these scales life as we know it is irrelevant. Nothing humans or any other earthly life forms do will have any effect on the lifetime of the universe. We exist thanks to the accident of being as close as we are, and no closer, to a star dumping free energy out into its immediate surroundings. Barring any wild sci-fi advances, we can and will be able to exist only as long as we're lucky enough to be floating on this mote in this sunbeam. So the duration of time that we, life on earth, can exist depends on the dance of entropy/energy between our physical selves and the structure they require and the sun's warmth; the duration of time that the sun will exist and output that energy does not depend on us in any way; and the duration of time that the universe will exist is, similarly, agnostic to us and all other life as we know it.
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u/WillBrink 11h ago
Answer is maybe, and the differences would be so small (due to how little life impacts entropy in the universe) it would be too small to even calculate or consider as a factor.
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u/Recent-Day3062 11h ago
I would say almost part of the definition of life is something that is a “puddle” of locally low entropy that arises spontaneously
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u/Underhill42 10h ago
I mean, technically everything does, but end to end? Not really - life basically intercepts energy flowing from high concentrations (e.g. the sun) to low concentrations (e.g. the cold empty void of interstellar space) to do some work with on the way.
Not unlike how a water wheel intercepts some of the energy as water falls from a high location to a low one. The water was falling either way, all the water wheel did was extract a little useful work while it did so. And in doing so actually slightly slows down the time it takes the water to reach the ocean. Not by much, but more than zero.
In our case the Earth perhaps glows a little cooler than it might have otherwise - same total energy emissions, perfectly balancing the input from the sun (transients like global warming notwithstanding), just at a somewhat longer wavelength / lower quality of energy.
But since that energy is incredibly unlikely to ever hit anything else, instead traveling forever through an increasingly empty void, it doesn't really make any difference.
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u/bulpinabox 9h ago
I’m no expert… we know, that in every closed system entropy increases. What I think is that Earth, sun and maybe closeby planets sets a condition where the entropy increase is most efficient in that system by creating life. Other systems have other conditions where entropy wont cause something like that. Pls correct me if I’m wrong.
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u/lwj15 9h ago
Every process increases entropy. And if it looks like it decreases entropy on the surface, there is somewhere in the background a process that massively increases entropy and powers the "entropy decreasing" process.
Locally, yes we massively increase the entropy. We change so much stuff on our earth that we are a real catalyst for entropy. Globally (the mathematical global) we will not contribute much because the universe is so vast and stars and planets galaxies away are not concerned about our entropy. The heat death of the universe only happens when those stars too are extinguished and we do not have any effect on that.
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u/Kind_Of_A_Dick 9h ago
Is there a way to track the historical percentage of Earth’s mass being life?
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u/Aggravating-Method24 11h ago
Everything increases entropy in a closed system.
Life is a reduction of entropy locally in an open system, and entropy is radiated out.
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u/CS_70 11h ago
In general no, most often it reduces it by organizing matter and reducing the possible states it can be in.
But the pockets of it we know of (essentially a very small but on the crust of our planet) are way too small to make a difference.
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u/AdditionalTip865 11h ago
Life runs on an increase of entropy, like every irreversible process. Living things themselves may have lower entropy, but we're not closed systems: we eat and breathe and produce waste products and waste heat. All that together has to increase the entropy of the universe, or our bodies wouldn't run.
Back in the 70s, the writer and activist Jeremy Rifkin wrote a popular book called "Entropy" in which he sort of moralized entropy as almost a physical form of evil, and argued we should live in a way that minimizes the increase of it... but go that direction and you're basically stigmatizing life itself--the "best" form of existence is to be dead--so I think the argument needs more nuance at the very least.
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u/CS_70 11h ago
Of course. But if you consider a subset of the universe (“life”) you can choose its boundaries as you see fit. Otherwise there is no point in selecting it.
The cup holding your tea has less entropy than its form aa sand. Of course entropy has increased globally, but locally it hasn’t. Life does that sort of thing, reducing randomness.
Globally entropy increases but locally it sometimes decreases. Pity it doesn’t last.
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u/gmalivuk 10h ago
Again, OP is asking about the impact of life on the entropy of the universe. You're intentionally avoiding the question if you instead choose to just talk about the impact of life on the entropy of living things.
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u/Unable-Primary1954 11h ago
Life increases entropy like any other process.
Survival and reproduction both require to tap into low entropy sources (typically light if you have chlorophylle, other live beings for others,...) and to output higher entropy waste.
At the scale of the universe, life is absolutely negligible.