Entropy: What the Heck Is the Deal with That?

The human being is an organism that takes perfectly good food and manufactures it into crap.

    -- On a toilet stall wall somewhere at the University of British Columbia

So we covered the FIrst Law of Thermodynamics, concerning Energy.  The Second Law is Entropy.  Almost nobody knows what entropy is, including most scientists.  Brilliant physicist Max Planck referred to it as a "mathematical spook."  Mathematician John Neumann, advising a learned colleague on what to call a certain property he'd uncovered, said:

"You should call it entropy, because nobody knows what entropy really is, so in a debate you will always have the advantage."

Even the guys who are supposed to know what entropy is don't know what entropy is.  It's that twisted.

Here is what entropy is. 

What's that squiggly thing before the Q?

I won't bother to explain it, I just like the way it looks.  Mathematics can be quite poetic; it can articulate profound concepts with the stroke of a few lines.  Like Joyce Kilmer should have said,

I think that I shall never see

A poem lovely as is E

=mc².

The mathematical equation above is the most succinct definition, but here are some other definitions:

1.      Heat will not flow spontaneously from a cold object to a hot object.

2.      Any system which is free of external influences becomes more disordered with time. This disorder can be expressed in terms of the quantity called entropy.

3.      You cannot create a heat engine which extracts heat and converts it all to useful work.

4.      The total sum of information in the universe is diminishing to zero.

5.      Time’s arrow.

Entropy says that heat will flow from a hot body to a cold body, but not the other way around.  Simple enough.  Intuitive.  You pull muffins out of the oven and they cool down and the room heats up a bit. Every time.

But entropy is the only law in science that says that will happen. Theoretically, the air in the room could drop a few degrees and use that energy to cook your muffin batter while it is sitting on the counter. But that never happens.  Hot flows to cold, but cold does not flow to hot. It is not reversible.  Entropy, like time, only happens in one direction; it only increases.  Time is irreversible and entropy is a measure of irreversibility. 

If it weren't for entropy, we might not have a concept of time at all.  Fascinating--what began as a study of heat and work in engines leads us to an insight about time itself.

Or you can think of entropy, in a sense, as things moving from order to disorder. Think of the heat in the muffins as red checkers, and the cool in the room as black checkers.  After a while, when the room and the muffins are at the same temperature, the red checkers and black checkers are all mixed. up.  It'll take work to separate them again (by putting the muffins back in the oven, for example).

This is illustrated in many songs:

All you do, crumbles to the ground though we refuse to see (Kansas)

It falls apart (The Odds)

Everything turns to shit (Marilyn Manson)

So, while the First Law of Thermodynamics says you can't win (energy cannot be created), the Second Law says you can't even break even (entropy always increases; there will always be irreversible losses in a system; energy dissipates; order moves to disorder).  But, bless the dreamers out there, this has not slowed down the number of patents filed for such machines, and I refer the reader to  the Museum of Unworkable Devices to see some of these marvelous contraptions.  However, bowing to the Second Law, the United States Patent Office no longer accepts patents for perpetual motion machines unless you can show them a working model.

So energy is not destroyed (First Law) but, when used, it is always degraded (Second Law).  When we use energy it moves from high quality (low entropy, order, concentrated) to lower quality (higher entropy, disorder, dissipated).

Human beings, for example, take high quality energy (food), extract work from it (calories), and then expel lower quality energy (crap and waste heat).  We extract and use high quality energy from the environment in order to keep our metabolisms in an odered state (in order, if you will, to stave off the tide of entropy in our own bodies). 

As you'll see in the next column, it is not energy we are trying to conserve when we switch off the lights, but energy quality or Exergy.  And that produces some neat insights into how we can better interact with the environment around us, and perhaps even some clues to the nature and origin of life. 

I'll leave you with a riddle.  You're in a perfectly insulated room.  No heat escapes.  You open the door of the fridge and leave it open. Does the room:

(a)    cool down

(b)    heat up

(c)    stay the same temperature.

Think about it.  All you need to answer this is in today's post.  No consulting the Goggle Oracle! Answer tomorrow.