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Someone Explain to me Entropy before I die!


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I think you may be over thinking it then, entropy is just randomness, or disorder in the universe. The second law of thermodynamics states that the level of entropy always increases in a closed system, which means that as time goes by, things become disorganized.

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Entropy is disorder, when anything isn't organised into groups or patterns. If you drop a stack of paper (which was organised into a nice, neat stack) and watch them fly everywhere thats the trend of the universe to progress towards entropy. Entropy is based on chance though, there's a chance they could all fall into a nice neat pile or into a complex pattern like a word. The chances are that they won't though. You can of course force things into organisation, the energy your body expends is on forcing things into particular organisations. Unfortunately this produces heat and heat is very disorganised energy. If you put it in numbers (which I can't do) then the organisation produced by your body is outweighed by the disorganisation you give off by heat. So we need a constant supply of organised energy which we get from the sun.

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You need to make sure you understand the first law of thermodynamics before you tackle the second(entropy).

 

Hopefully this will clarify things:

 

Symmetry, Broken-Symmetry and the First and Second Laws ofThermodynamics

 

The laws of thermodynamics are special laws that sit above the ordinary laws of nature as laws about laws or laws upon which the other laws depend. It can be successfully shown that without the first and second laws, which express symmetry properties of the world, there could be no other laws at all. The first law or the law of energy conservation which says that all real-world processes involve transformations of energy, and that the total amount of energy is always conserved expresses time-translation symmetry. Namely, there is something that unifies the world (constitutes it as a continuum) which if you go forward or backward in time remains entirely the same. It is, in effect, through this conservation or out of it that all real-world dynamics occurs, yet the first law itself is entirely indifferent to these changes or dynamics. As far as the first law is concerned, nothing changes at all, and this is just the definition of a symmetry, something that remains invariant, indifferent or unchanged given certain transformations, and the remarkable point with respect to the first law is that it refers to that which is conserved (the quantity of energy) or remains symmetric under all transformations.

 

Entropy and the Second Law of Thermodynamics

 

The second law of thermodynamics (the entropy law or law of entropy) was formulated in the middle of the last century by Clausius and Thomson following Carnot's earlier observation that, like the fall or flow of a stream that turns a mill wheel, it is the "fall" or flow of heat from higher to lower temperatures that motivates a steam engine. The key insight was that the world is inherently active, and that whenever an energy distribution is out of equilibrium a potential or thermodynamic "force" (the gradient of a potential) exists that the world acts spontaneously to dissipate or minimize. All real-world change or dynamics is seen to follow, or be motivated, by this law. So whereas the first law expresses that which remains the same, or is time-symmetric, in all real-world processes the second law expresses that which changes and motivates the change, the fundamental time-asymmetry, in all real-world process. Clausius coined the term "entropy" to refer to the dissipated potential and the second law, in its most general form, states that the world acts spontaneously to minimize potentials (or equivalently maximize entropy), and with this, active end-directedness or time-asymmetry was, for the first time, given a universal physical basis. The balance equation of the second law, expressed as S > 0, says that in all natural processes the entropy of the world always increases, and thus whereas with the first law there is no time, and the past, present, and future are indistinguishable, the second law, with its one-way flow, introduces the basis for telling the difference.

The active nature of the second law is intuitively easy to grasp and empirically demonstrate. If a glass of hot liquid, for example, as shown in Figure 3, is placed in a colder room a potential exists and a flow of heat is spontaneously produced from the cup to the room until it is minimized (or the entropy is maximized) at which point the temperatures are the same and all flows stop.

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Originally posted by fafalone

Plagiarism is a violation of scienceforums.net policy. Consider this your final warning.

 

WHAT!!!??? It's not plagerism. I'm not tendering that text as my own work.

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I think its clear to all its not his own work and that he was not tryign to pass it off as his own when it contains "as shown in Figure 3"...

 

now, if he submitted this to articles or something as his own work, then it would be clearly plagarism

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Originally posted by MajinVegeta

How do you describe the entropy of a black hole?

there is an equation: S=Akc[su]3[/sup]/4hbar G

 

 

What's the relationship, exactly? Is it the radiation?

 

That's a tough one to explain but I believe has to do with the relationship of entropy between the inside and outside of the event horizon. Stuff goes into the black hole, entropy increases inside the event horizon and decreases outside.

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  • 1 month later...
Originally posted by Deslaar

That's a tough one to explain but I believe has to do with the relationship of entropy between the inside and outside of the event horizon. Stuff goes into the black hole, entropy increases inside the event horizon and decreases outside.

 

Not sure what you are refering to here. But outside the event horizon of a black hole lies the natural universe, where entropy must increase, rather than decrease.

 

That said, this is not always the case. Particles can be created at the event horizon and cast off into the universe. Spontaneous creation of a particle qualifies as order from disorder, hence, for a split second, entropy increases outside the black hole.

 

See Hawking Radiation or vaccum fluctuations

 

As far as inside the black hole, one can surmise that entropy must also increase, at least down to one Planck length from the singularity. Unless you assert that there is an unknown force at work inside a black hole capable of over-coming the 2nd law :D

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Not necessarily... remember that the law of entropy doesn't say entropy in any system is always increasing, it just says that the entropy of the universe as a whole is increasing, so certin systems (i.e. life) can naturally violate it.

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Originally posted by fafalone

Not necessarily... remember that the law of entropy doesn't say entropy in any system is always increasing, it just says that the entropy of the universe as a whole is increasing, so certin systems (i.e. life) can naturally violate it.

I completely agree, and your comprehension of entropy is remarkable, considering how misunderstood it usually is. However, when entropy is reversed in a local system, one can generally identify the process responsible for it. I was merely stating

 

A. We don't know that entropy is reversed inside a black hole, though theory tells us it is not.

 

B. If it is, we certainly do not know the mechanism responsible. So some assertions must be made.

 

That was my only point.

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