Some questions about scientific laws..

[KeilanS]

First off, I'll say that I make no claim to be a scientist, if any of my information is untrue, tell me so.

Okay, well I have read about something called the Law of Entropy, or the Second Law of Thermodynamics. This law states that all things tend towards chaos, unless energy is added. Now this goes quite strongly against the big bang theory. How could the random chemicals and condensed matter turn into the entire universe without outside energy. Also, how could a monkey turn into a man?

Now I'm not sure on this one, but I also have heard that if a rotating object breaks into pieces, those pieces will be rotating in the same direction as the original object. So if the rotating sphere of condensed matter exploded, how come everything in the universe doesn't rotate the same way?

[Bread_of_Life]

Hello Keilan, my name's Nikolai, I read physics at Imperial College, London. Maybe I can help answer your questions.

The second law of thermodynamics is actually a restatement of the first law of thermodynamics, but with one thing added - entropy. Entropy is effectively a made up variable (that is, it doesn't *directly* represent something we've observed, like heat, or motion) - but the reason we need it in there is to represent the fact that heat can only flow in one direction, from hot to cold, not from cold to hot. The first law of thermodynamics allows for heat to flow either direction - but we know from experience that in this universe, heat flows naturally and exclusively from hot to cold. So we made a variable called entropy that expresses this fact, and hence the second law of thermodynamics.

Now, the consequence of this law and this new variable is that, when you do the maths, you find that in a closed system (one in which no energy is added or taken away) entropy can only ever increase. If you're allowed to put energy into a system (an open system), entropy can increase or decrease - but if the system is closed, if no energy goes in, entropy will either stay the same or increase. It cannot decrease.

Now, because entropy is a made up variable, scientists have long argued as to exactly what it "represents" in real life. There are various ways that we can think of entropy in real life. One way is the capacity of a system to do useful work. The higher the entropy, the lower the capacity of a system to do useful work. The lower the entropy, the more useful work a system can do.

Another way of thinking of entropy is as a measure of order or disorder. The lower the entropy, the greater the order of a system. The higher the entropy, the greater the disorder of a system. What that means is that a closed system can only ever get more disordered, overall, although be careful, there is a very specific scientific meaning to the word "disordered" here - I won't go into it, but it's just a warning!

So, back to your question:

How could the random chemicals and condensed matter turn into the entire universe without outside energy.

And this is why I warned you about the scientific meaning of order and disorder. The original big bang nucleus - the particle that exploded to make everything - was just about as ordered as you can get, by the scientific definition. It had extremely low entropy by necessity. Everything after it has had higher and higher entropy, including the entired universe. It may look more ordered to you, but in actual fact, it's becoming more and more disordered by the entropic definition.

Also, how could a monkey turn into a man?

Even better question my dear boy, how can a zygote turn into a man? 25 years ago I was a single cell in my mother womb - how can it be that I am now a fully grown man - with much greater order?

The answer is, here, the input of energy. I am not a closed system - I eat food, and excrete food. Energy goes in one end, and comes out the other. I am not bound physically by ever increasing entropy.

Similarly, earth is not a closed system, and nor are other animals, so evolution is not bound by ever increasing entropy either. By the way, just a side point of correction, monkeys and man came from the same ancestor, they are cousins - monkeys didn't turn into man.

Now I'm not sure on this one, but I also have heard that if a rotating object breaks into pieces, those pieces will be rotating in the same direction as the original object. So if the rotating sphere of condensed matter exploded, how come everything in the universe doesn't rotate the same way?

The law you refer to is called "the conservation of angular momentum". What it actually states is that, if something is spinning and breaks apart - if you ADD UP all the angular momenta of the pieces, they will ADD UP to the same as the original. It's the same if two spinning things collide - if you add the angular momenta before and after the collision, the addition will be the same.

So let's imagine a sphere breaks up in to 5 pieces. The original angular momentum of the sphere is 10. The 5 pieces have angular momenta:

1

3

5

2

-1

In other words, one of the pieces, the fifth piece, is moving with backwards spin. Perhaps it collided with piece 3 awkwardly and got sent spinning slowly backwards. However, if you add up all these angular momenta, they still add up to 10. In other words, the law of conservation of angular momentum has not been broken. This is how some moons and planet have "retrograde" or "backward" spin. It is notable that these planets usually have weird off centre axes as well - because usually what caused them to spin backwards was a collision, knocking their axes off centre at the same time.

I hope this answers your question.

[KeilanS]

That makes sense, thank you.

[billie]

Hey, Keilan, thought you stayed out of Apologetics? I knew you wouldn't be able to resist!

[KeilanS]

Hey, Keilan, thought you stayed out of Apologetics? I knew you wouldn't be able to resist!

I have very strict rules with Apologetics. When I do venture in here, it's only because I have something to ask. But I treat it kind of like a museum. Only look at things if you're ready to be bored by them and DO NOT at all costs touch anything, you never know, it might explode.

[Floatingaxe]

Even better question my dear boy, how can a zygote turn into a man?

That is hilarious! A zygote is a cell of MAN. A monkey is a plain old monkey! We repeat after our OWN KIND.

The only ancestor of mankind is mankind. Give me a break!

[Anne]

Hey, Keilan, thought you stayed out of Apologetics? I knew you wouldn't be able to resist!

I have very strict rules with Apologetics. When I do venture in here, it's only because I have something to ask. But I treat it kind of like a museum. Only look at things if you're ready to be bored by them and DO NOT at all costs touch anything, you never know, it might explode.

Quick lock all the exits, we've got him trapped!

[Bread_of_Life]

Floatingaxe,

Actually, a zygote is a single undifferentiated cell. It is a lot less ordered than I (by the physical definition of order) - a human being made up of billions of cells - each differentiated and forming complex organs with their own functions. In other words, going from a zygote to a fully grown human being implies a decrease in entropy - something that can only be achieved through the input of energy.

Going from an ape-like ancestor to a man, may or may not involve a decrease in entropy. Is an ape-like ancestor more or less ordered than a human? It is a good question, and one that is not simply answered, even if we had the specimen in front of us.

However, this is not a debate about evolution, it was a simple question about entropy, and I explained how entropy worked. Perhaps you should read the question as context for how I answered it, before criticising my answer.