Isolated system

If a wall of lead is one lightyear thick, it will stop half of the neutrinos. The perfectly isolated system is hard to accomplish. Still we can make approximate calculations. Assuming the neutrino has a non-vanishing rest mass, and some hypothetical particles do not exist, we can experimentally verify the second law of thermodynamics.

Metrological aspect of enthalpy

H=U+p*V

U is the 'inner energy'

p is the pressure

V is the volume

A table tells us that enthalpy, ΔH, for combustion of fat is 3700000 J/kg. Rather it is the conjugate: minus 3700000 J/kg, since the energy is given away from the system. But how do we make this intelligible to the common man? What relevance have pressure and volume? None. What we actually measure is ΔH. There is no method of measuring U or ΔU. We burn fat and read the termometer. From this reading we calculate the change in enthalpy. You might believe scientists have a special machine that goes 'ping' and reveals everything on the computer screen. It is often much simpler. Medieval instruments like balance scales are still in use in our laboratories. In these latter days there is still not a reproducible definition of 'kilogramme'.

When you read

• ΔG=ΔH-T*ΔS

it may confuse you. The difference in free energy equals difference in ethalpy minus the actual temperature times the difference in entropy. How do we measure this? Do we have an entropymeter in the laboratory? No ΔS is calculated from thermometer readings. What is the purpose of this mumbo-jumbo? It is to tell if a process is spontaneous. If ΔG is less than zero, the process is spontaneous. This means that a process could be spontaneous if it demands heat, if the entropy is increasing. I am not sure this is the simplest way of viewing it, but it is the conventional way.

Alas, if our calculations will only show the process beeing spontaneous, there is no way of telling whether it will happen. Try and try again!

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Warning! The Shannon entropy is often denoted 'H'. However, 'S' is more appropriate.

Recycling

Did you learn in school, that every real process is irreversible? Due to friction and other awkward stuff, energy will degenerate. This might be true, but did you calculate how much you lose? *) There is a myth of the increasing entropy of the universe. Stay calm! It is not growing that fast. 'Heat death' will wait some hundred billion years.
During that time we will be able to contiue our research. Just now we know only 5% of the matter. The rest is 'dark'. Maybe the freezing world is not inevitable, after all.
Some processes are approximately reversible, and the amount of increasing entropy is negligible.
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http://en.wikipedia.org/wiki/Heat_death_of_the_universe

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*)
Strain out a gnat

If the system has a termal energy=1 J, then the entropy could be distributed like this: S as function of T (T=[1; 373] K)

If temperature increases 100 K, the entropy will increase by 0,04. We have greater obstacles in the world. "You strain out a gnat, but swollow a camel."

Isn't she beautiful?

Ada created an algorithm, that is regarded as the first computer program.

Alas the machine was not as beautiful as she was.

The right wing

"Mathematics is nothing more, nothing less, than the exact part of our thinking." (Brouwer)

How the hell could he be so sure? And his 'mathematics' differed from that of the left wing: the formalists. I envy people, that are convinced of having the truth. Is math in all our minds? (Obviously some think cricket is more interesting.)

I think I will start a new coterie called 'The Wrong Wing'. Math is just a game and not a divine reality, as some seem to think. Many have tried to formulate the ultimate theory about everything, but all have failed. Failure is our heritage.

David Hilbert was a member of the Swedish Academy of Science, and I think he had a nice hat.

knowledge or trust

Science predicts exactly the motion of bodies. That is the point of having science. An alternative to science could be submission (voluntary, of course).

Freedom of choice

When a single electron has to choose between two slits, it chooses to travel through both.

When a man makes the choice, he walks just one way, and denies himself the other. Man has free-will and a mind - the electron has not.

Science is very predicting, and therefore an enemy of free-will. Science can foretell full-moons, weather and passover. I am afraid research will leave humanity with no choice: Trust in God. Otherwise we will be bound to an inexorable fate, ruled by the Demon of Laplace.

• "We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes." (Pierre-Simon Laplace)

I choose spam for breakfast, like I did yesterday and the day before that. I can not afford anything else, but I still have FREE-WILL.

Text entropy

One of these texts has higher entropy than the other.
Which one is it? Do you still think 'entropy' stands for 'disorder'? Is the text of Shakespeare less "ordered" than the arbitrary monkey writings? If you think so, my friend, you need professional care.
The ideal chrystal has the least entropy, and "life" has much higher. That is the truth, even if you read otherwise on the web. 'Entropy' is not - and will never be - 'disorder'. It does not matter how you define this dubious term.

/Nicholas Bourbaki
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Respecting the copy rights of Georgia State University, I will not tell you, what they say about entropy, but it is wrong. Honestly I don't think they will admit being wrong, if I write to them.