Encapsulation, inheritance and polymorphism

Steven D'Aprano steve+comp.lang.python at pearwood.info
Fri Jul 20 10:27:26 CEST 2012


On Fri, 20 Jul 2012 08:20:57 +1000, Chris Angelico wrote:

>>>       Since the current evidence indicates the universe will just keep
>>> expanding, it's more of a "deep freeze death..."
>>
>> Heat death means *lack* of heat.
> 
> The second law of thermodynamics states that energy tends to go from
> higher states to lower, with heat being the very lowest. It's possible
> to do work using (say) kinetic energy, and in the process, some of that
> energy becomes heat. It's also possible to do work with any difference
> in temperature (eg Stirling engines), so the state of the universe in
> which it's no longer possible to do any work will be one in which all
> energy is heat and everything's at the same temperature. That doesn't
> mean a lack of heat; in fact, it implies that there'll be rather more
> heat than there now is, because we currently have a whole lot of
> chemical energy available to be used.

Yes, but the point is, that heat will be *incredibly* diffuse, 
essentially spread over the entire universe, which will be MUCH bigger 
than it is now, and hence the temperature will be low even though the 
total amount of heat will be high.

The average temperature of the universe now is about 2.7 degrees above 
absolute zero (i.e. 2.7 K, -270.45 C or -454.81 F), with individual 
hotspots reaching into millions of degrees or higher. By the time the 
last of the stars burn out, the average temperature will be a minuscule 
fraction of a degree above absolute zero, and the only hotspots will be 
the slowly cooling neutron stars.


> But in any case, that's a looooooooong way off...

I once went to an astronomy lecture where the lecturer was talking about 
the eventual death of the sun. He said, "In about 10 billion years, the 
sun will consume almost all of its fuel. It will cool and expand into a 
red giant, and the earth will be engulfed by the expanded sun and 
destroyed."

This fellow sitting next to me got all agitated, stood up and cried out, 
"Does the government know about this? We have to do something!"

The lecturer said "Don't worry sir, there's no need to panic, this won't 
happen for billions of years."

The fellow looked relived and said "Oh thank god, I thought you said 
*million*!"



-- 
Steven



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