johnson1010 wrote: Entropy, for those who don't know, is a measure of order. A house is an example of an ordered, or low entropy set of objects. think of all the parts and particles that make up the house. Think of the zillions of ways they could be arranged, if you say, tossed the whole thing into the air and let it fall a hundred times. A rubble pile is an example of a disordered, or high entropy set of objects.

For each of the hundred times the house was dropped it would fall into a rubble pile. Each individual rubble pile is unique and in it's own way as unlikely as a miracle, considering the zillions of different arrangements a rubble pile could be composed of. But landing in the shape of a house is just not going to happen because as amazing and unlikely any PARTICULAR rubble pile is, ANY rubble pile is far far far more likely than any kind of house.

I like to think of "houses" as being endothermic. They require energy resources be put into them, they require order be applied to them. Rubble piles are exothermic. You don't have to do anything to a house to find, one day, it has turned into a rubble pile. The energy and resources have "left" the house. It has fallen from one of only a few million possible designs that equal "house" and into one of the billions and billions and billions of possible configurations for "rubble pile"

Thanks for this, I very much like your house / rubble pile analogy. Since, as far as I can make out, the terms 'endothermic' and 'exothermic' refer quite specifically to energy in the form of 'heat', they are, in the context of the house analogy, a bit more difficult to place (though I think principally accurate), but what is certainly the case is that in a low-entropy system (low level of disorder, high level of order) like the house, there is contained a lot of energy that can, while in the process of conversion to another form of energy, be said to be able to carry out some 'useful work', whereas in a high-entropy system (high level of disorder, low level of order) like the pile of rubble that energy has been spent or, as you so elegantly put it 'left the house'.

Going back to the question of what is time, this adds an interesting facet (I was going to say 'dimension', but that would rather confuse things more than necessary...): if entropy - which I believe we can perceive as a phenomenon and describe in terms of thermodynamics (whence also, of course, your introduction of 'endothermic' and 'exothermic' principles) - 'exists' and is the cause of changes in molecular constellations (motion), that, on its own, continues until all molecular constellations and within them all subatomic constellations have put themselves into perfect disorder (which in terms of thermodynamics is also perfect balance), at which point no further motion of any description is possible, then does that make entropy the underlying 'cause' of time. Is time, in fact, basically a function of entropy? And since entropy is a concept pertinent to energy, is time, therefore, like matter, like heat, like motion, but one more aspect of energy?

Thanks for this, I very much like your house / rubble pile analogy. Since, as far as I can make out, the terms 'endothermic' and 'exothermic' refer quite specifically to energy in the form of 'heat',

That’s right. I don’t mean to say that a house is literally endothermic, but just to use it as a sort of analogy. Endothermic reactions require energy be put into them. Exothermic reactions release stored energy.

Loosely speaking, ordered objects have energy stored in them. Or, rather, energy has been put into them to make them ordered.

Here’s Brian Cox with his informative sand caslte analogy.



That’s a great clip.

But, ok, so why are things more likely to be in a high entropy state (disorder) than a low entropy state (order)?

Matter, energy tends toward lower energy, and therefore more stable configurations. Not because stable configurations are “preferable” in any way, but because of the definition of stability. Stable things last, while unstable things do not. So if you start off with 50% stable things and 50% unstable things, eventually the stable things will be all that's left. And what makes something unstable is high energy content. The more energy contained in some arrangement, the harder all the little pieces are railing against whatever force there is that binds them together. It takes energy to keep this stuff together.


This pattern exists in stellar nuclear synthesis as well. Hydrogen is the lightest single atom. Yet hydrogen forced together release energy and make helium. How would a hydrogen atom release energy when forming helium, which is heavier than hydrogen?

Because 1 helium is lighter than 2 hydrogen, and therefore at a lower, more stable energy. When the nuclei combine they release the extra mass in the form of energy and a neutrino. This pattern persists all the way up to iron, where the two lighter elements lose mass when forming the heavier element, so that the total is less than the parts. Iron is the goldilocks element, though. Elements heavier than iron don’t release energy when they fuse. They require energy be put INTO them. Because they are so heavy they are unstable. That’s why the elements at the very heavy end of the periodic table have to be made in particle accelerators and evaporate as soon as they are formed. They are too massive and too unstable.

Photosynthesis makes carbon and oxygen out of CO2. CO2 is the more stable compound and in order to tear it apart plants require the energy of the sun. But carbon and oxygen would very much prefer to be together again (prefer being an unfortunate word choice). It doesn’t take much to reverse that pattern back into CO2. Just raise the temperature a bit and the whole thing races to be back in the lower, more stable energy configuration in a chain reaction we call fire.

All this ramble is an attempt to illustrate how and why things fall into disorder.

if entropy 'exists' and is the cause of changes in molecular constellations (motion), that, on its own, continues until all molecular constellations and within them all subatomic constellations have put themselves into perfect disorder ,at which point no further motion of any description is possible, then does that make entropy the underlying 'cause' of time. Is time, in fact, basically a function of entropy? And since entropy is a concept pertinent to energy, is time, therefore, like matter, like heat, like motion, but one more aspect of energy?

I think it is accurate to say that energy is really all that we know anything about. Matter is just a sort of crystallized energy, and it can be thawed in nuclear reactions.

Entropy does exist, but I would be careful saying it was the ‘cause’. It’s consequential. The causes are the forces of nature. Gravity, electromagnetic, strong and weak forces. These are what propel particles in relation to each other (and inertia). The process by which these particles trend toward uniformity and disorder is called entropy, but that word is a description of the process, not the root of it, if you dig what I’m saying.

Fire, for instance, is an event that introduces greater entropy, but the agent at work there is the electromagnetic forces of chemistry.

I would say that the arrow of time is understood through entropy, because it is this continual shift away from the starting state that we can recognize as forward progress of time. Without this trend toward disorder everything could return to it’s starting point (including the neurons in our heads) and we couldn’t tell the difference.

Whoa.



What if that DOES happen, but the only thing we are capable of noticing is when things progress away from that ordered state because the second time you are in that instant you don't recognize that you were in the future, then regressed? What if time progresses ten seconds, then goes backward ten seconds all across the universe, and we never remember that little branch of history?



HAHA!

SCIENCE!

Never mind that last bit of nonsense. Entropy is statistics. Time goes forward because the odds are overwhelmingly stacked toward any of the bajillions of other states than the 1 previous state of the universe that was the past. The odds of everything reversing are even more insignificant than the cast of Jersey Shore.

johnson1010 wrote: Entropy does exist, but I would be careful saying it was the ‘cause’. It’s consequential. The causes are the forces of nature. Gravity, electromagnetic, strong and weak forces. These are what propel particles in relation to each other (and inertia). The process by which these particles trend toward uniformity and disorder is called entropy, but that word is a description of the process, not the root of it, if you dig what I’m saying.

thanks for this, johnson; that was most elucidating. (and i wish i could like prof d:ream more than i do - i know he means well and does as he means and is probably an all-round good egg; he just gets on my nerves, irrationally...) - i do 'dig' what you mean about 'causing' and 'describing' a process, and that's actually clarified something for me, so cheers!

the next question then is this: if - purely on the laws of probability - entropy always only goes up and the level of order always only decreases (and i think there is broad agreement that this is the case, except for the point at which we approach absolute zero, where entropy, i understand, also approaches zero), how come into this soup of molecular activity that seeks chaos, comes a force that not only looks for, but creates order of an extremely specific kind: life. and beyond that, intelligent, conscious life.

if entropy does describe time and explains why time can only move forward, then does a force that does the opposite of what entropy describes, namely create order deliberately, mean that we are ourselves capable of manipulating time, slowing down, even time? in a way i suppose that's what we are doing: we are putting patterns and structures into the world that we imbue with meaning and so in direct relation to these patterns and structures, time effectively slows down, is overcome for a while: the matter that makes up a pyramid keeps its shape and its meaning for several thousand years; had no conscious decision been taken to shape these rocks, order them and attach symbolic meaning to their arrangement, then time, as far as they and we are concerned, would simply have passed in its normal way. but because we ordered these rocks, we can go 'back in time' and receive communication from our ancient forefathers understand something about them; be, in a small way, with them in their day, so to speak...

the next question then is this: if - purely on the laws of probability - entropy always only goes up and the level of order always only … how come into this soup of molecular activity that seeks chaos, comes a force that not only looks for, but creates order of an extremely specific kind: life. and beyond that, intelligent, conscious life.

The second law of thermodynamics speaks about closed systems specifically. An internal combustion engine is such a system, where after just a little bit of time all the energy is spent, or at least rendered unusable to the system, and it shuts down. Unless you continue to input energy.

The earth is not a closed system. We are bombarded by a tremendous amount of solar energy on a daily basis, the very vast majority of which is never put to any use. Of that energy which is used by photosynthetic plants, the majority of THAT energy is lost to wasteful processes. Then herbivores eat the plants, and only retain like 10 percent of that energy. And so on. So what that means is any energy we put out there to create order pales in comparison to the energy being spent on disorder just on our planet. In addition, if you find something which at one point had been ordered, like a fallen down tree fort, then spend time to re-construct the fort you have put order back into the world. But in the doing, you have spent many calories of energy sawing nailing and hauling which cannot be recuperated in the same way you are attempting to resurrect the tree fort. This spent energy is adding to entropy. Consider the energy that went into the food you ate to supply the energy for that fort.

Think of one cheeseburger. That was a cow, or a couple of cows, who spent years eating food which we also grew, which needed to be tended, fertilized, harvested and hauled to the cows, who in turn need all the same treatment, but more so, since they burn much more energy in the course of a day than the grain did.

So when you eat a calorie of beef, you are actually eating the product of many hundreds of calories which by the time they get to you are a mere scrap of all the energy that’s gone into them. The answer there is, no matter what effort you put forward to generate order, the very effort of it is putting you in the red.

You are a pebble in a stream. Whatever water you manage to hold up for a second doesn’t compare to the vast torrent passing all around you, and then you leave a swirl in your wake further disrupting the water.

if entropy does describe time and explains why time can only move forward, then does a force that does the opposite of what entropy describes, namely create order deliberately, mean that we are ourselves capable of manipulating time, slowing down, even time?

I think metaphorically you could say that, but I don’t know that it has any significance literally. As I said above, in the process of adding order you are adding in more chaos. And to move backward in time you would have to restore something that was previously ordered to that ordered state again. You can do that superficially with the tree fort for example, but you cannot stop the weathering of the wood, or the heating and cooling of the fort, or the activity of life in and around the fort. Not to mention the molecular and subatomic activity going on inside the fort continuously.

the matter that makes up a pyramid keeps its shape and its meaning for several thousand years; had no conscious decision been taken to shape these rocks, order them and attach symbolic meaning to their arrangement, then time, as far as they and we are concerned, would simply have passed in its normal way. but because we ordered these rocks, we can go 'back in time' and receive communication from our ancient forefathers understand something about them; be, in a small way, with them in their day, so to speak...

Symbolism is an interesting thing to think about. Our world would not be possible without symbolic representation. I can use this computer because all the inventors in line before Microsoft had their knowledge preserved. I don’t have figure out maxwell’s equations of electricity. It’s just sitting there in a book for me to look at. I don’t have to spend my whole life figuring these things out, and I still reap the benefits. Its amazing, really!

I haven’t given a lot of thought to how symbolism is retained through all this. It’s true physical objects can be preserved, and some physical objects have been inscribed with symbols which can be interpreted later and this is the preservation of order. The same applies, I think, with the fort example, in that you have to expend tremendous resources to preserve these physical arrangements. Something like the standard model of physics can be represented in essentially a paragraph of text. It doesn’t require THAT much energy to chip that into a stone and it would be preserved for a very long time. If you are familiar with physics, however, you would be able to reap a very great deal of information from this small equation. Much more than is implied by the amount of symbols in it.

But then you have to imagine that not just anybody will be able to make any sense of the thing. You can’t put that in front of a fourth grader and have them puzzle out the meanings on their own. To get them to the level where they can even begin to appreciate it also requires a huge amount of resource investment and energy expenditure on their part to prepare them to unpack the dense symbolism of the standard model master equation.

Interesting questions.

johnson1010 wrote:
Interesting questions.

Yes, I reckon we're probably into quite different territory now from what ant had started. And although they are both intrinsically - I would argue inseparably - tied into our ability to develop anything that we may understand as civilisation, the two new strands that are emerging from this discussion, thermodynamics and energy on the one hand and symbolisation on the other, probably each merit their own topic here.

But thanks for the extraordinarily stimulating discussion, I appreciate the opportunity to stretch my own thinking a little further than it normally has to...