studiot Posted July 12 Posted July 12 53 minutes ago, Agent Smith said: Si, that's what threw me off, but what about the fact that the earth is a closed system? We're not adding stuff to the system, First a warning Be careful about the use of the terms open and closed systems. An open system can exchange energy, matter, momentum and charge with its surroundings. A closed system can exchange energy and momentum but not matter or charge with its surroundings. An isolated system cannot exchange either energy, matter, momentum, or charge with its surroundings. Some use closed when they really mean isolated, but I think you mean closed. However, as joigus +1 has pointed out, it is not that simple. The Sun generates particles of high energy and momentum. They do not constitute a great influx of mass but most are charged and if these were to 'land' on Earth our environment would be very different. Luckily for us Earth has an unusually strong magnetic field, as planets go, which deflects most of these and interactions only take place in the far upper atmousphere. Further in the past larger masses with enormous momentum have arrived. An example would be the asteroid that killed the dinosaurs. You should also realise that Earth's atmousphere was very different in the more distant past. In fact it has undergone at least two major changes of composition, firstly after hundred of millions of years of near continual rain on the original rocks created the conditions for life and then even more dramatic changes by life itself from an anoxic state to an oxygen rich state. The technical term for the stabilisation we current enjoy, but climate change is degrading, is buffering. In particular the carbonate and bicarbonate buffers in the oceans. Note here that fresh water (lakes and rivers) have no such buffer. Here is a schematic of this effect. 1
exchemist Posted July 12 Posted July 12 13 minutes ago, studiot said: First a warning Be careful about the use of the terms open and closed systems. An open system can exchange energy, matter, momentum and charge with its surroundings. A closed system can exchange energy and momentum but not matter or charge with its surroundings. An isolated system cannot exchange either energy, matter, momentum, or charge with its surroundings. Some use closed when they really mean isolated, but I think you mean closed. However, as joigus +1 has pointed out, it is not that simple. The Sun generates particles of high energy and momentum. They do not constitute a great influx of mass but most are charged and if these were to 'land' on Earth our environment would be very different. Luckily for us Earth has an unusually strong magnetic field, as planets go, which deflects most of these and interactions only take place in the far upper atmousphere. Further in the past larger masses with enormous momentum have arrived. An example would be the asteroid that killed the dinosaurs. You should also realise that Earth's atmousphere was very different in the more distant past. In fact it has undergone at least two major changes of composition, firstly after hundred of millions of years of near continual rain on the original rocks created the conditions for life and then even more dramatic changes by life itself from an anoxic state to an oxygen rich state. The technical term for the stabilisation we current enjoy, but climate change is degrading, is buffering. In particular the carbonate and bicarbonate buffers in the oceans. Note here that fresh water (lakes and rivers) have no such buffer. Here is a schematic of this effect. Exactly. Buffering is the term. There are processes that react to change by mitigating it, but which do not restore the system to quite the same state. 1
Agent Smith Posted July 12 Author Posted July 12 2 hours ago, studiot said: First a warning Be careful about the use of the terms open and closed systems. An open system can exchange energy, matter, momentum and charge with its surroundings. A closed system can exchange energy and momentum but not matter or charge with its surroundings. An isolated system cannot exchange either energy, matter, momentum, or charge with its surroundings. Some use closed when they really mean isolated, but I think you mean closed. However, as joigus +1 has pointed out, it is not that simple. The Sun generates particles of high energy and momentum. They do not constitute a great influx of mass but most are charged and if these were to 'land' on Earth our environment would be very different. Luckily for us Earth has an unusually strong magnetic field, as planets go, which deflects most of these and interactions only take place in the far upper atmousphere. Further in the past larger masses with enormous momentum have arrived. An example would be the asteroid that killed the dinosaurs. You should also realise that Earth's atmousphere was very different in the more distant past. In fact it has undergone at least two major changes of composition, firstly after hundred of millions of years of near continual rain on the original rocks created the conditions for life and then even more dramatic changes by life itself from an anoxic state to an oxygen rich state. The technical term for the stabilisation we current enjoy, but climate change is degrading, is buffering. In particular the carbonate and bicarbonate buffers in the oceans. Note here that fresh water (lakes and rivers) have no such buffer. Here is a schematic of this effect. By a "closed system" I perhaps mean there's no change in mass i.e. conservation of mass of what could be considered a chemical reaction and without that, the set point wouldn't change, it would jiggle/wiggle perhaps but there would be no jumps. That diagram is interesting but could it be just a small window we're getting to look through (make a copy of the graph, flip it horizontally and connect the lines and we have a self-regulation, oui? The time spans on a geological scale are for humans, acintya (imponderable). 2 hours ago, exchemist said: Exactly. Buffering is the term. There are processes that react to change by mitigating it, but which do not restore the system to quite the same state. Is the buffer mechanism so powerful as to stave off the inevitable. Perhaps a combination of buffer + negative feedback loops define Gaia's autocorrect 🙂 Maybe if there are any coders among us, he could do a simulation for us.
studiot Posted July 12 Posted July 12 1 hour ago, Agent Smith said: By a "closed system" I perhaps mean there's no change in mass i.e. conservation of mass of what could be considered a chemical reaction and without that, the set point wouldn't change, it would jiggle/wiggle perhaps but there would be no jumps. That diagram is interesting but could it be just a small window we're getting to look through (make a copy of the graph, flip it horizontally and connect the lines and we have a self-regulation, oui? The time spans on a geological scale are for humans, acintya (imponderable). Please do not do this. I first thought you simply quoted me and had not responded. Replies should not be place within the quote you are responding to. What do you mean flip it horizontally and why would you do it ? pH is the dependent variable and volume of added acid is the independent one Do you know the difference ? You cannot specify the pH - that is the whole point of a buffer. And yes it is a form of self regulation. But you can specify how much acid is added.
Agent Smith Posted July 12 Author Posted July 12 (edited) This, the above, is what really happens (self-correction), but we were shown only half the picture. Edited July 12 by Agent Smith
sethoflagos Posted July 15 Posted July 15 On 7/12/2024 at 7:13 AM, Agent Smith said: Gracias for bringing up Le Chatelier's principle; Cogito the point in re natural equilibrium I was making is precisely this principle. @exchemist is right, the set point will change i.e. if the initial equilibrium point was maintained at levels of constituents A, the subsequent equilibrium would've moved away from A. However this would require an external source for the constituents of a chemical reaction. Since the earth is, as far as I can see, a closed system in that respect, there's a good chance that the equilibrium point is constant i.e. the Gaia hypothesis could be true. Please be aware that we are not talking about thermodynamic equilibrium here as that is incompatible with life processes (which depend on the existence of various gradients). Some of us (me included) have used the term 'equilibrium' when what we actually intend is better described as 'steady state'. This supports @joigus comment on solar influx and the consequent gradients of temperature, pressure, concentration, density etc that drive most of the Earth's surface processes, both organic and inorganic. 1
studiot Posted July 16 Posted July 16 14 hours ago, sethoflagos said: Please be aware that we are not talking about thermodynamic equilibrium here as that is incompatible with life processes (which depend on the existence of various gradients). Some of us (me included) have used the term 'equilibrium' when what we actually intend is better described as 'steady state'. This supports @joigus comment on solar influx and the consequent gradients of temperature, pressure, concentration, density etc that drive most of the Earth's surface processes, both organic and inorganic. All +1
joigus Posted July 16 Posted July 16 14 hours ago, sethoflagos said: Please be aware that we are not talking about thermodynamic equilibrium here as that is incompatible with life processes (which depend on the existence of various gradients). Agreed. One has to be quite far away from equilibrium for anything "interesting" happening. @exchemist has made a point that's always been on the back of my mind as a considerable objection, or at least an obstacle, to the Gaia hypothesis, which is the one about homeostasis. Geological processes generally are one-directional and relentless, so it seems difficult to see them as part of a global flow of inter-dependent feedback mechanisms that would lead to this stasis (quite distinct from thermodynamic equilibrium, as you justly point out) that homeostasis represents. Also, @studiot added this careful distinction between closed and isolated systems which, whether or not is crucial here, could be important. For example, the Earth continually receives an influx of particles from space, although it reflects basically just light. This makes the Earth a system that's neither closed (energy) nor isolated (matter), strictly speaking. But these processes are perhaps slow in comparison to typically life-related cycles. Can the same be said about geo-processes like weathering or recycling of material in subduction zones? I wonder. I wonder as well whether the fact that the Gaia hypothesis has been given considerable creedence may be because some processes are faster, while other (geological, cosmic) are far slower and act more as a background that's fixed or periodic of much higher period for the purposes of the bio-processes to adjust. Does any of that make sense, even if it's a tad vague?
studiot Posted July 16 Posted July 16 1 hour ago, joigus said: Agreed. One has to be quite far away from equilibrium for anything "interesting" happening. @exchemist has made a point that's always been on the back of my mind as a considerable objection, or at least an obstacle, to the Gaia hypothesis, which is the one about homeostasis. Geological processes generally are one-directional and relentless, so it seems difficult to see them as part of a global flow of inter-dependent feedback mechanisms that would lead to this stasis (quite distinct from thermodynamic equilibrium, as you justly point out) that homeostasis represents. Also, @studiot added this careful distinction between closed and isolated systems which, whether or not is crucial here, could be important. For example, the Earth continually receives an influx of particles from space, although it reflects basically just light. This makes the Earth a system that's neither closed (energy) nor isolated (matter), strictly speaking. But these processes are perhaps slow in comparison to typically life-related cycles. Can the same be said about geo-processes like weathering or recycling of material in subduction zones? I wonder. I wonder as well whether the fact that the Gaia hypothesis has been given considerable creedence may be because some processes are faster, while other (geological, cosmic) are far slower and act more as a background that's fixed or periodic of much higher period for the purposes of the bio-processes to adjust. Does any of that make sense, even if it's a tad vague? Gaia is a very seductive notion that offers great comfort. Unfortunately it does not accord with our observations and experience. Since it is nevertheless a great subject for discussion I am going right back to the beginning and giving @Agent Smith +1 for introducing it. I can't tell if he is still follwing this but I seem to remember from a couple of years ago that his main interest is biology ( there was an interesting foray into mathematics) and main language French. Most of the discussion to date has centered on processes. Yet Gaia is about a state. So it is important to distinguish between states and processes. States may be instantaneous, transient or persistent (steady state). They are described by the 'values' of a number of variables called state variables. Processes evaluate these state variables and come in many varieties. These values may be quantitative or qualitative. Some processes have an input and a definite output or result. Feedback is such a process. But there is a larger category which is 'self reinforcing' or 'regenerative' or 'auto-correcting' or 'auto-regulating'. Chemical buffers, for instance, have no input or output. There are also categories best associated with the equilibrium concepts of stable, unstable and metastable. These do not have an input or output and best represent the Gaia hypothesis. Gaia suggests that there is an ideal state for the Earth. In fact I have already observed that there have been several stable states in the past, persistent over timescales orders of magnitude greater than our current arcadian, benevolent Gaia. There are many interesting points for expanded discussion here, if anybody is interested. 1
sethoflagos Posted July 16 Posted July 16 3 hours ago, joigus said: Agreed. One has to be quite far away from equilibrium for anything "interesting" happening.@exchemist has made a point that's always been on the back of my mind as a considerable objection, or at least an obstacle, to the Gaia hypothesis, which is the one about homeostasis. Indeed. I can see how homeostasis manifests at an ecosystem level: populations that consume a vital resource faster than it can be replenished will see birth rates decline and mortality increase; likewise, genetically homogeneous over-dense populations are likely to be thinned out by disease. These are classic negative feedback loops that have an intrinsically stabilising effect on all ecosystems. Extending this idea to the far more complex biochemical processes of an individual seems problematic as @exchemist has suggested. There's just too much going on in there for such a simplistic mantra to help understand the fine detail. Midway between these two levels, the potential impact of a game-changing single point mutation in the genome of a single individual is worth considering. Even a modest increase in the reproductive success of that individuals descendants creates a self-sustaining positive feedback that can completely overturn the status quo in relatively few generations. Entire new phyla have arisen through such events. Evolution is blind to future consequences. It operates strictly in the present and cares not a jot for long-term stability. 3 hours ago, joigus said: Also, @studiot added this careful distinction between closed and isolated systems which, whether or not is crucial here, could be important. For example, the Earth continually receives an influx of particles from space, although it reflects basically just light. This makes the Earth a system that's neither closed (energy) nor isolated (matter), strictly speaking. But these processes are perhaps slow in comparison to typically life-related cycles. Can the same be said about geo-processes like weathering or recycling of material in subduction zones? I wonder. Weathering is driven mainly by insolation; plate tectonics is predominantly driven by the gradual loss of the planet's internal heat. Neither is steady-state in any sense other than their usually extremely slow evolution towards a final lifeless thermodynamic equilibrium. Hence: 4 hours ago, joigus said: I wonder as well whether the fact that the Gaia hypothesis has been given considerable credence may be because some processes are faster, while other (geological, cosmic) are far slower and act more as a background that's fixed or periodic of much higher period for the purposes of the bio-processes to adjust. Does any of that make sense, even if it's a tad vague? Yes * 2
dimreepr Posted July 16 Posted July 16 3 hours ago, studiot said: Gaia suggests that there is an ideal state for the Earth. No it doesn't, Gaia suggests the earth is always in an ideal state for Earth, it's life that has to fit in...
TheVat Posted July 16 Posted July 16 AFAICT, no Gaian homeostasis would prevent Earth from becoming more like Venus over time. The sun's luminosity increases something around 10% in the next billion years, so well before then all the ice will melt, and all water will evaporate, triggering a runaway greenhouse effect. As happened on Venus, temps rise to hundreds of degrees, basically cooking out the carbon in the crust and putting it into the atmosphere which will hasten the effect. And no Mars style solidification of the core (with loss of magnetosphere) will kick in first (core is cooling too slowly for that), so there won't be a solar wind peeling off most of the air and water vapor for a cooling effect. (and the Mars scenario comes with some ionizing radiation, so not so good for a biosphere) 1
studiot Posted July 16 Posted July 16 2 hours ago, TheVat said: As happened on Venus, temps rise to hundreds of degrees, basically cooking out the carbon in the crust and putting it into the atmosphere which will hasten the effect. How much calcium carbone would be decomposed on present day Venus, given the following information Venus surface temp about 450oC Surface pressure 95 bars On Earth at 1 bar calcium starts to decompose at about 650oC 2 hours ago, dimreepr said: No it doesn't, Gaia suggests the earth is always in an ideal state for Earth, it's life that has to fit in... Try again. Firstly I said that over time the Earth has been in several different (persistent) states. Life in those early states could not exist today and life today could not exist in those early states. I think you will find that Gaia assumed that the current state has always existed, which is definitely not true. 3 hours ago, sethoflagos said: Weathering is driven mainly by insolation; plate tectonics is predominantly driven by the gradual loss of the planet's internal heat. I think it is wise to be careful with terminology here. Weather (and thereofore weathering) is driven by insolation reaching the surface. Climate is largely controlled by plate techtonics. For example the precambrian 'snowball earth' occurred because plate tectonics at that time clustered pretty well all the land at a pole in one giant supercontinent. At the time of formation of most of England, tectonics dictated that the piece of crust that would eventually become England, lay in tropical latitudes experiencing a tropical climate under a shallow sea. Today of course, we enjoy the 'cool temperate climate' , at temperate latitudes halfway to the other pole. Exchemist quoted the carbon cycle for discussion and I think this is very good idea. On 7/11/2024 at 11:27 AM, exchemist said: My understanding is that homeostasis refers to a stable biological state that resists being changed, as a result of some regulatory feedback. There is no such regulatory feedback implied by the reversibility of this reaction. However if you were to expand the scope of the question to look at the Earth's carbon cycle, there is a kind of balance, with carbon sources and sinks more or less in equilibrium: https://en.wikipedia.org/wiki/Carbon_cycle I'm not sure it is correct to call that homeostasis though, as many of the components involved are not biological. One point about the carbon cycle is that the process is well, cyclic. Cyclic processes have neither input not output and feedback is therefore inapplicable. Exchemist further makes the point that the carbon cycle consists of several stages or sub processes which have the capacity to accumulate or disperse carbon so a complete passage round the cycle is a very complicated affair which takes a long time and can be subject to further external influences.
TheVat Posted July 16 Posted July 16 5 hours ago, studiot said: How much calcium carbonate would be decomposed on present day Venus, given the following information DK. My impression is that carbon decomposition happens in multiple pathways as temps rise, so it does not all hinge on baking limestone. Acidification, ignition of coal seams, vulcanism, and other means. And then, in the Venus scenario, evaporating oceans and resultant vapor cover magnify the CO2 effect. A geochemist could probably get more specific on your question. 5 hours ago, studiot said: Climate is largely controlled by plate techtonics. I would vote for a citation on this.
studiot Posted July 16 Posted July 16 1 hour ago, TheVat said: I would vote for a citation on this. The climate in any given place depends firstly upon where that place is on Earth. So land today above the 70th parallel (Greenland, Antartica etc) experiences an arctic climate. But location is not the only factor. The 30th parallel runs through the Missippi Delta, Florida and the Yangtse. It also runs through the Himalaya and the Sierra Madre which experience quite a different climate. These differences are basically due to the elevation of the two mountainous area compared to the at or near sea level locations. Over time, both location and elevation are brought about by plate tectonic activity. My apologies for the poor spelling in my previous post. Other factor include the proximity of water bodies and the wind system. Again we find that the Monsoon is caused by the presence of the Himalaya, ( Waters of the World by Sarah Dry) which in turn is caused by tectonic activity. There are also other lesser factors such shielding and orbital factors which determine the climate at a given location, but it is tectonics that place the land there (or not). I don't think there is one single citation that contains all the explanationsyou have to draw from a variety of sources. The BBC documentary series I referred to in (I think) my 3rd post also discusses some of this.
sethoflagos Posted July 17 Posted July 17 (edited) 10 hours ago, studiot said: One point about the carbon cycle is that the process is well, cyclic. Cyclic processes have neither input not output and feedback is therefore inapplicable. I'm sorry, but I'm having difficulty following your reasoning here. Surely, for each stage of a simple lossless cycle, the output moreorless by definition eventually returns as the input - a positive feedback loop of unity gain. What am I missing here? Without feedback playing a substantial part in the carbon cycle, it's hard to see how tipping points could even be a thing, positive or negative. 10 hours ago, studiot said: I think it is wise to be careful with terminology here. Weather (and thereofore weathering) is driven by insolation reaching the surface. Climate is largely controlled by plate techtonics. For example the precambrian 'snowball earth' occurred because plate tectonics... Again, I seem to be missing the point you're trying to make. Perhaps it's age catching up with me. Geological weathering, irrespective of the local climate, requires an external energy input to maintain itself indefinitely, doesn't it? Does not the overwhelming majority of that energy come ultimately from the sun? 5 hours ago, TheVat said: A geochemist could probably get more specific on your question. A clue might be in the large amount of sulphuric acid in the Venusian atmosphere. Carbonates and strong acids tend not to coexist for very long. Edited July 17 by sethoflagos sp
Agent Smith Posted July 17 Author Posted July 17 On 7/16/2024 at 12:46 AM, sethoflagos said: Some of us (me included) have used the term 'equilibrium' when what we actually intend is better described as 'steady state'. Words are slippery, thought viscous vicious. Apologies for abuse of terminology. My chemistry files are from the late 1990s. Perhaps chemical terms have been revised. Muchas gracias for the correction. I understand "equilibrium" gives us the wrong impression that a reaction has terminated, when in fact all that's happened is AmountProduced(Reactants) = AmountProduced(Products). Correct? On 7/16/2024 at 12:46 AM, sethoflagos said: Please be aware that we are not talking about thermodynamic equilibrium here as that is incompatible with life processes (which depend on the existence of various gradients). Thermodynamic equilibrium meaning cessation of (thermal) energy flux? Very unlike a steady state, if my description of it (vide supra) is accurate. 23 hours ago, joigus said: I wonder as well whether the fact that the Gaia hypothesis has been given considerable creedence [sic] I was under the impression that The Gaia Hypothesis was high fashion, appealing but lacking substance, which in science means lacking supporting evidence or strong counterevidence against it. The latter comes in the form of, among other things, a Wikipage on so-called natural balance, where a few scientists have claimed the exact opposite is true i.e. many ecosystems spiral out of control and collapse; even the extremely credible and popular belief that predators-prey regulate each others' population, so the claim is, is false. @exchemist did good by bringing up the motile set point of the steady state. However, the earth is, as far as I can tell, a closed system. If the two factors in a steady state are A and B then if there's more of A then there's less of B and vice versa. For the set point to move, there's got to be an external source or sink for A and B, which seems unlikely (throwing darts here) because in 4.5 billion years (earth's tentative age) all of these must have saturated, leaving the biosphere as the only "chemical reaction" active in the current geological epoch 🤔 18 hours ago, dimreepr said: No it doesn't, Gaia suggests the earth is always in an ideal state for Earth, it's life that has to fit in... That's evolution. 22 hours ago, studiot said: Yet Gaia is about a state. So it is important to distinguish between states and processes. My usual ... miss the finer points. Verum, processes determine the state, in the sense of mechanism I suppose. There may even be supervening states based on the simple chemical processes that I outlined in the OP. I mean, among other thingss, what about systemic (solar system) and galactic (milky way) and intergalactic (Virgo Supercluster) ... you get the idea ... "ecology". I'll leave that thought there. @sethoflagos, really good examples of (positive/negative) feedback mechanisms, but you seem reluctant to jump on board, for good reasons of course. If we have real instances of authentic homeostasis then, at the very least, The Gaia Hypothesis can't be ruled out with confidence. Just curious, what's a lossless cycle? 10 hours ago, TheVat said: I would vote for a citation on this. 💯 16 hours ago, studiot said: Firstly I said that over time the Earth has been in several different (persistent) states. Life in those early states could not exist today and life today could not exist in those early states. I think you will find that Gaia assumed that the current state has always existed, which is definitely not true. I would have to agree with you. I have my doubts about the conditions for biogenesis being the same as that for biosustenance. Your point, mutatis mutandis, exactly, oui? 16 hours ago, studiot said: Cyclic processes have neither input not output and feedback is therefore inapplicable. Each step in a cycle identifies a specific chemical product, unless you mean physical cycles e.g. the water cycle.
exchemist Posted July 17 Posted July 17 57 minutes ago, Agent Smith said: Words are slippery, thought viscous vicious. Apologies for abuse of terminology. My chemistry files are from the late 1990s. Perhaps chemical terms have been revised. Muchas gracias for the correction. I understand "equilibrium" gives us the wrong impression that a reaction has terminated, when in fact all that's happened is AmountProduced(Reactants) = AmountProduced(Products). Correct? Thermodynamic equilibrium meaning cessation of (thermal) energy flux? Very unlike a steady state, if my description of it (vide supra) is accurate. I was under the impression that The Gaia Hypothesis was high fashion, appealing but lacking substance, which in science means lacking supporting evidence or strong counterevidence against it. The latter comes in the form of, among other things, a Wikipage on so-called natural balance, where a few scientists have claimed the exact opposite is true i.e. many ecosystems spiral out of control and collapse; even the extremely credible and popular belief that predators-prey regulate each others' population, so the claim is, is false. @exchemist did good by bringing up the motile set point of the steady state. However, the earth is, as far as I can tell, a closed system. If the two factors in a steady state are A and B then if there's more of A then there's less of B and vice versa. For the set point to move, there's got to be an external source or sink for A and B, which seems unlikely (throwing darts here) because in 4.5 billion years (earth's tentative age) all of these must have saturated, leaving the biosphere as the only "chemical reaction" active in the current geological epoch 🤔 That's evolution. My usual ... miss the finer points. Verum, processes determine the state, in the sense of mechanism I suppose. There may even be supervening states based on the simple chemical processes that I outlined in the OP. I mean, among other thingss, what about systemic (solar system) and galactic (milky way) and intergalactic (Virgo Supercluster) ... you get the idea ... "ecology". I'll leave that thought there. @sethoflagos, really good examples of (positive/negative) feedback mechanisms, but you seem reluctant to jump on board, for good reasons of course. If we have real instances of authentic homeostasis then, at the very least, The Gaia Hypothesis can't be ruled out with confidence. Just curious, what's a lossless cycle? 💯 I would have to agree with you. I have my doubts about the conditions for biogenesis being the same as that for biosustenance. Your point, mutatis mutandis, exactly, oui? Each step in a cycle identifies a specific chemical product, unless you mean physical cycles e.g. the water cycle. On one point, please don't describe the Earth as a closed system. Someone, I forget whom, has already pointed this out on the thread. It may be virtually closed as far as matter is concerned but from the thermodynamic point of view, which is how the term is generally used, it is an open system, absorbing radiation from the sun and itself radiating, in the Infra-red, out into space. This energy flow is itself an important contributor to the state of the planet, as the current climate change issue, which is a classic example of an equilibrium being shifted, demonstrates. Specifically, the temperature of the Earth at which the inflow and outflow of radiation is in balance is changing, upward, due to a slowdown in the rate of escape of radiation from the Earth. 1
Agent Smith Posted July 17 Author Posted July 17 20 minutes ago, exchemist said: On one point, please don't describe the Earth as a closed system. Someone, I forget whom, has already pointed this out on the thread. It may be virtually closed as far as matter is concerned but from the thermodynamic point of view, which is how the term is generally used, it is an open system, absorbing radiation from the sun and itself radiating, in the Infra-red, out into space. This energy flow is itself an important contributor to the state of the planet, as the current climate change issue, which is a classic example of an equilibrium being shifted, demonstrates. Specifically, the temperature of the Earth at which the inflow and outflow of radiation is in balance is changing, upward, due to a slowdown in the rate of escape of radiation from the Earth. Allow me to clarify. The closedness I refer to is in terms of matter. Is that wrong in any way? It's the solar energy, verum, that sustains the Gaia reaction, if I'm allowed to call it that. I imagine the Gaia reaction to be ubercomplex, but reducible to (chemical) cycles, much like in the human body; after all we are talking about homeostasis, right? You're correct about the upswing in temperature, partly because of increased solar output (some might say, as part of the solar cycle) and mostly due to the greenhouse effect. Going out on a limb, I'd say planetary-level (self)regulation occurs at scales we have yet to understand properly. What timing, eh? 😓 How about if I say ... if the Gaia hypothesis is false, what's the explanation for such long term stability in (let's focus on a small section of the sky) the concentration of atmospheric and marine chemical constituents (despite fossil fuel usage over a century)?
dimreepr Posted July 17 Posted July 17 18 hours ago, studiot said: I think you will find that Gaia assumed that the current state has always existed, which is definitely not true. Gaia as a hypothesis, is just another way to personify a force that's beyond our understanding, an ubermench if you will, with a very specific superpower. Other than that, we're definitely talking past each other. 1 hour ago, Agent Smith said: 20 hours ago, dimreepr said: No it doesn't, Gaia suggests the earth is always in an ideal state for Earth, it's life that has to fit in... That's evolution. That's right... 🙄
studiot Posted July 17 Posted July 17 56 minutes ago, exchemist said: On one point, please don't describe the Earth as a closed system. Please check your definitions. There are umpteen explanations and diagrams on the net. 2 hours ago, Agent Smith said: I understand "equilibrium" gives us the wrong impression that a reaction has terminated, when in fact all that's happened is AmountProduced(Reactants) = AmountProduced(Products). Correct? Yes that is correct 2 hours ago, Agent Smith said: Thermodynamic equilibrium meaning cessation of (thermal) energy flux? Very unlike a steady state, if my description of it (vide supra) is accurate. Yes that is correct 2 hours ago, Agent Smith said: Each step in a cycle identifies a specific chemical product, unless you mean physical cycles e.g. the water cycle. The water, and other geological cycles, are still processes. Note that most chemical reactions are actually multistep and the kinetics can be very complicated. I prefer to use the word stage rather than step because step I can then Identify a stage with a formal state and a step which is part of the way and may be near instantaneous. I will address other points more fully later 2
joigus Posted July 17 Posted July 17 1 hour ago, Agent Smith said: I was under the impression that The Gaia Hypothesis was high fashion, appealing but lacking substance, which in science means lacking supporting evidence or strong counterevidence against it. I don't know, to be honest. I suppose whether you work on marine biology or epigenetics, it is of little consequence to your work. The discipline I would assume it is likely to influence more is evolutionary biology. But again, I don't really know. I figure it would be difficult to evaluate the actual level of impact on scientists' minds. 1 hour ago, Agent Smith said: However, the earth is, as far as I can tell, a closed system. This people say over and over, but is not true. @exchemist seems to agree with me in this point. Mind you, I'm sure he knows volumes more than I do about these matters. Here's my point: Quote The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. The composition of the solar wind plasma also includes a mixture of particle species found in the solar plasma: trace amounts of heavy ions and atomic nuclei of elements such as carbon, nitrogen, oxygen, neon, magnesium, silicon, sulfur, and iron. There are also rarer traces of some other nuclei and isotopes such as phosphorus, titanium, chromium, and nickel's isotopes 58Ni, 60Ni, and 62Ni.[2] Is that of little consequence? I don't know. I do know it has been argued that fluxes of cosmic rays due to relatively close supernova explosions might have been responsible for certain extintion events. so I wouldn't bet my bottom euro on it being totally inconsequential. Is the Earth to a good approximation a closed system for long periods of time? Probably yes. But it is an approximation. It is certainly true that the Earth was not a closed system during the late heavy bombardment, when even whole chunks of the Moon might have rained upon "us". It wasn't either 65 mya, when the Chicxulub crater formed and swept away all the dinos, AFAWK. At times like those, the Earth certainly opened the gates, and dramatically so.
StringJunky Posted July 17 Posted July 17 (edited) Have you guys heard of 'Daisy World'? This is the model used to explain GH in its most basic terms. Here's a NASA vid on the subject of albedo and negative feedback loops. Edited July 17 by StringJunky
studiot Posted July 17 Posted July 17 43 minutes ago, joigus said: Is the Earth to a good approximation a closed system for long periods of time? Probably yes. But it is an approximation. Have you seen the comments on this in my previous post? 2 hours ago, Agent Smith said: I understand "equilibrium" gives us the wrong impression that a reaction has terminated, when in fact all that's happened is AmountProduced(Reactants) = AmountProduced(Products). Correct? I said there would be more 1 hour ago, Agent Smith said: How about if I say ... if the Gaia hypothesis is false, what's the explanation for such long term stability in (let's focus on a small section of the sky) the concentration of atmospheric and marine chemical constituents (despite fossil fuel usage over a century)? Look at these notes about equilibrium, and perhaps Wikipedia. The idea is that a system is in stable equilibrium if following a small displacement or disturbance it returns to the original state. Unstable equilibrium it moves (rapidly) to another state Metastable equilibrium if it may do either. My example is a marble in a bowl (stable) a marble on a bowl (unstable) a marble on a ledge (metastable) The importance of this is that it provides a restorative mechanism for the process of disturbance without feedback. More of this later.
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