1 &2 Law of Dynamics, Confusing

[The_Catholic]

Please, only Catholic responses, no atheists or agnostics or even anti-evolutionists. I don’t want this thread to go a dozen different ways.

I’ve been pondering and pondering and pondering this today and it’s driving me absolutely nuts! Lol. But that’s my obsessive thoughts, I have OCD. Anyway, the First Law of Thermodynamics is: “Energy can be converted to one form to another, but it can not be created nor destroyed.” The second: “Any system left to its own fades away. Stars burn out, a newly fashioned wooden table slowly decays, a steaming hot cup of tea gradually cools.”

1. What’s confusing me is this: Alright, what exactly does it mean for “energy” to convert from one form to another? Also, if energy cannot be created nor destroyed, wouldn’t that suggest that all of the energy that makes up the universe, which at one time was crammed together into a ball the size of a needle point prior to the Big Bang explosion, has just always existed? Since it can’t be *created *or destroyed. Or is that law saying that nothing *in this physical universe *has the ability to create and/or destroy such energy? As I imagine (which makes more “logical” sense) that God with His great power created this universe, created this universe’s energy, and created the laws of energy for this universe. Know what I’m saying?
2. Now, the second law seems to contradict the first, does it not? (I know I’m misunderstanding the laws, as I’m sure if they were truly contradictory then scientists would have discarded them long ago) But the second law states that “systems” burn out, like stars. Are not stars energy? If they’re burning out then they’re being destroyed, a contradiction to the first law. Were our sun to burn out, let’s say in a million years, there would be no more energy to power our solar system and the earth would die, including all her energy which comes to life because of the sun, but now the sun would be no more and so all the energy surging this galaxy would be destroyed. Right? Again, does this not contradict the first law? Because how could the universe’s energy have always just existed in the state of a “pin” prior to the big bang (as what the first law seems to suggest to me, unless I’m misunderstanding it) if the energy or “system” has been gradually decaying?

See the confusion? The first law seems to suggest the universe’s energy is eternal, the second law seems to suggest the universe had a beginning. How can both laws be intertwined and harmonized? I’m sure they can and are; I just can’t figure it out and I’m obsessing over it L

 

[neophyte]

I have a degree in Mechanical Engineering, and got very high grades in Thermodynamics, I’m qualified by training and experience to clarify these questions properly, and I’ll do my best.

First Law-
Let’s say that a certain amount of energy from the sun falls as light onto a solar cell. Some of that energy is turned into electricity, some of it is turned into heat that warms up the panel, some of it is reflected back into the sky where it’s absorbed by dust and water and gets turned into heat. If you add up all of the energy of the electricity, the genereated heat, and the rest you’ll find out that it’s the exact same amount of energy that was in the light that came from the sun.

Now take the electricity, and send it to a motor that raises a weight or to a chemical cell that creates some compound. In addition to the energy used to raise the weight or make the compound, there will be stray heat generated, maybe noise will be made or sparks created that give off light. If you add up the energy used to raise the weight, make the compound, generate the heat, noise and light, you’ll find that it’s exactly equal to the energy of the electricity that went into the machine.

So that’s what’s meant by the statement that energy is not created or destroyed, but merely changed from one form to another.

Second Law -
This one’s much, much more difficult to explain or understand. To complicate things, the common explanations of what the Second Law says and means are simply wrong.

A full answer would take several thousand words and a bit of math, but in short the Second Law is a mathematical description of the ability of the energy of a system to do work. It states: “In a closed system, entropy increases for irreversible processes and remains constant for reversible processes”. Another way it can be stated is “There can be no machine whose only effect is to cause heat to flow from a cold body to a warm body.” And yet again, “There can be no machine that converts heat energy into an equal amount of work”. In other words, no machine is 100% efficient.

As for the beginning of the universe, that’s a special case. At the conditions present during a Big Bang, the normal laws of physics, as we understand them, break down. All of the math falls apart, so we can’t say whether or not the Second Law applies then.

At the end of the universe… well, again it depends on how the universe ends. If it all just goes cold, then all of the energy will still be present, but it will be spread out evenly so it won’t be available to do work. Kind of like the water behind a dam - as long as the water level behind the dam is higher that it is downstream then water will flow and you can get work out of it. But if there’s no difference in water level there can be no flow of water, and so it will be impossible to get any work out of the system.
Does this help?

Once I told one of my professors that I’d been thinking about entropy, and quick as a wink he said “Oh, my, don’t do that, you’ll hurt yourself!!” He said it very earnestly, too, and I found out that he was right. It gave me a migrane for about 15 years. It’s a dictum that there are three stages of understanding the Second Law. First you haven’t the slightest idea what it means. Then you do know what it means. Finally, you realize that you really haven’t got the slightest idea at all but you can do the math and get the right answers.

I think I’m entering Stage 3.

 

[Spirithound]

There are several “forms” of energy. Two are static and kinetic. I’m going to use the example of my arm and a bag of groceries (one of those new “green” burlap bags, filled with 34 mandarins, to be specific)

If I hold the bag in my outstretched arm, 3 feet above the ground, the bag possesses static or “potential” energy. If I drop it, it then has kinetic energy. This is a conversion of energy.

The first law does indeed (in the form you gave) imply that the universe’s energy has always just existed. However, science often does not account for the awesome power of God. As Catholics, we realize that science is not designed to put God into the equation, and we can further say that God set up physical laws for us to find out and bust our brains over. As Catholic scientists, we can then put in the proviso about God whenever we’re talking to the appropriate audience.

On to the second law, and this is where the really fun part begins.

…tried to carry on my example…got too complicated…But, to use your example, the sun would burn out, but it has already radiated its heat-energy outwards. In other words, energy is not being destroyed, heat-energy is being transformed into light-energy. Regarding the energy of everything on Earth, the bodies would hit the floor; their potential energy is used up. Plants and animals would die, but would up much of their energy trying to brave the cold. Some potential energy would be left, in the form of bodies unable to rot because even the bacteria froze to death, but that energy would still exist, it’s not going anywhere. Alternatively, the sun will become a super-nova, and we will all be converted into the sun’s heat-energy.

I fear I cannot answer your last couple questions, but since i’ve now bumped the thread, maybe someone can

 

[Thing]

The energy at the start of the universe, at the point of the pin as you said, is potential energy. But how did it become a point of energy? If that point of energy exploded into a universe what force was holding it back before it exploded? And if nothing was holding it back from exploding, does that mean that the point was stable? If so, what force outside that point caused the stable point to explode? But hang on a minute. What is energy anyway? You can squash a universe into a point of possibly no dimensions, so what sort of stuff is energy? Is all the energy of the universe really contained in a point or is there scope for more understanding of the nature of energy.
‘Science’ laws only describe what we see happening, but what of the vast world beneath or behind those material concerns. Like the icebergs there is probably 90% of reality submerged from our view.