Post by Progenitor A on Mar 7, 2011 9:22:38 GMT 1
Now I don't really think much of Professor Brian Cox
But last night he did a good job with entropy and the arrow of time
OK, OK, it took an hour, cost hundreds of thousands in quite unnecessary 'location' shots that added little to his explanations that could not have been added on a beach in Brighton
So the programme was long-winded and flash, but nevertheless he made the concept of entropy and the arrow of time quite clear
Mind you , when you look at the 2nd Law of thermodynamics, you will have to look hard for a concept of entropy, but nevertheless I am happy to take the word of others that it is there
So entropy is the probability of disorder, so clearly demonstrated by the professor's pile of sand.
He took a pile of sand and churned it around and yet there was no change in its structure.
There are hundreds of billions of ways the grains of sand can be distributed that are each indistinguishable from the rest - the pile of sand remains simply a pile of sand.
Its Entropy- its susceptibility to disorder is large- that is because it is already very disordered.
A sand-castle on the other hand is very susceptible to disorder but has order. The wind blows grains off and changes its shape, it crumbles and loses its shape, it cannot tolerate interference without losing its form. Left on its own It will lose its form totally and become a mere heap of sand.
Its organisation is high, its Entropy is very low.
And that is the essence of Entropy - the 'decay' of systems toward disorder - disorder is the 'natural' state of things, anything else is ephemeral and will pass and disorder will assert itself
The very universe is descending into disorder - we are yet at a very early stage, but the inevitable approaching state is disorder, whereby matter will evaporate to a mass of uniform particles all at the same energy level everywhere - oddly the final entropy of the universe will result in a 'sameness' everywhere - a disorder so profound that it cannot be disordered any further!
And when the universe reaches that stage, it dies, it exists but it is dead.
Time has stopped because there is nothing to happen to measure time
(Now this is exactly the same point as Carnyx was making in another thread - brilliant Carnyx, I knew you had something there!)
And so organization gradually decomposing into disorganization and disorder is the arrow of time. Although we do not know why, that arrow is irreversible, things must go from order to disorder!
A pragmatic Law if you like, that has never been observed to be flouted
So low entropy is high order, high organisation, and is in fact, highly improbable - it is something that cannot last - it will decay to the highly probable state that is disorder where the entropy is high
Incidentally the link between 2nd Law of Thermodynamics entropy and Information Entropy was made much clearer to me by this programme
Well done Professor Cox, a well-made series of points!
(modified to get the right magnitude for entropy (entropy=1, high disorder, entropy=0 high order) iaw eammonshute's comment
But last night he did a good job with entropy and the arrow of time
OK, OK, it took an hour, cost hundreds of thousands in quite unnecessary 'location' shots that added little to his explanations that could not have been added on a beach in Brighton
So the programme was long-winded and flash, but nevertheless he made the concept of entropy and the arrow of time quite clear
Mind you , when you look at the 2nd Law of thermodynamics, you will have to look hard for a concept of entropy, but nevertheless I am happy to take the word of others that it is there
So entropy is the probability of disorder, so clearly demonstrated by the professor's pile of sand.
He took a pile of sand and churned it around and yet there was no change in its structure.
There are hundreds of billions of ways the grains of sand can be distributed that are each indistinguishable from the rest - the pile of sand remains simply a pile of sand.
Its Entropy- its susceptibility to disorder is large- that is because it is already very disordered.
A sand-castle on the other hand is very susceptible to disorder but has order. The wind blows grains off and changes its shape, it crumbles and loses its shape, it cannot tolerate interference without losing its form. Left on its own It will lose its form totally and become a mere heap of sand.
Its organisation is high, its Entropy is very low.
And that is the essence of Entropy - the 'decay' of systems toward disorder - disorder is the 'natural' state of things, anything else is ephemeral and will pass and disorder will assert itself
The very universe is descending into disorder - we are yet at a very early stage, but the inevitable approaching state is disorder, whereby matter will evaporate to a mass of uniform particles all at the same energy level everywhere - oddly the final entropy of the universe will result in a 'sameness' everywhere - a disorder so profound that it cannot be disordered any further!
And when the universe reaches that stage, it dies, it exists but it is dead.
Time has stopped because there is nothing to happen to measure time
(Now this is exactly the same point as Carnyx was making in another thread - brilliant Carnyx, I knew you had something there!)
And so organization gradually decomposing into disorganization and disorder is the arrow of time. Although we do not know why, that arrow is irreversible, things must go from order to disorder!
A pragmatic Law if you like, that has never been observed to be flouted
So low entropy is high order, high organisation, and is in fact, highly improbable - it is something that cannot last - it will decay to the highly probable state that is disorder where the entropy is high
Incidentally the link between 2nd Law of Thermodynamics entropy and Information Entropy was made much clearer to me by this programme
Well done Professor Cox, a well-made series of points!
(modified to get the right magnitude for entropy (entropy=1, high disorder, entropy=0 high order) iaw eammonshute's comment