I am slightly confused by this issue, as i understand just before the big bang there was a state of very low entropy which over time to the present day increased (because of the bang).

My question is how can there be ordered structures like galaxies ,planets and humans if entropy is supposed to increase over time. I know that its obvious gravity is responsible for matter coming together in stars etc but i dont know the full reason for the argument of entropy increasing with time.

Because entropy is allowed to decrease in local, open systems, such as a galaxy, or a planet.

Would u care to elaborate on that point, why is entropy only allowed to decrease in local regions of space?

The net entropy of a system always increases. It can decrease in some places, as long as it increases by a bunch in another area.

I find it interesting that it is only because of 'local' exceptions that planets formed, life evolved, and we can figure out the principles of thermodynamics. As to why such exceptions should proceed in this way, I lean with those who feel there are several levels of self-organising characteristics inherent in matter.

 

[i have to go now. There is a crowd at the castle gates,with torches, chanting 'weak anthropic principle', over and over.]

the crude example is....

if you regard your study room or bed room as a closed system, the entropy(disorder) of your room

has some inital value...say...like you put your belongings ( books , cloths ) in neat and orderly

fashion...so the entropy will be initally low...

and let's say there is a big bang in your room and everything get scattered around...and the

entropy get higher....

In hoping that you will lower the "higher entroy" by placing "things" back to their places...,

something unexpected happened that....although you may have succeeded in "ordering" your belongings, you

have had to exert some force to accomplish the work as well. That means you lower the room's entropy,

by the price of increasing it in your own body.

(like your muscles contract <= your cells burn carbs <= molecules breaks down <=...etc.)

 

so the overall entropy of a system is always increasing....

I always used to tell my mum it was futile, it will just get messy again.... never thought to use thermodynamics to argue the point though.