How does one prove the formula for entropy $S=-\sum p\ln p$?
Obviously systems on the microscopic level are fully determined by the microscopic equations of motion. So if you want to introduce a law on top of that, you have to prove consistency, i.e. entropy cannot be a postulate.
I can imagine that it is derived from probability theory for general system. Do you know such a line?

Once you have such a reasoning, what are the assumptions to it?
Can these assumptions be invalid for special systems? Would these system not obey thermodynamics, statistical mechanics and not have any sort of temperature no matter how general?

If therodynamics/statmech are completely general, how would you apply them the system where one point particle orbits another?


Question: magento creates two customer sessions with one browser for the same guest?
Answer: If the wrong session is used, it is because the session_name is wrong. The session name is set in Mage_Core_Model_Session_Abstract_Varien::setSessionName().

But after a look on the Stacktrace, I have no idea, why overwriting _construct or even __construct should be a problem here:

#0  Mage_Core_Model_Session_Abstract_Varien-&gt;setSessionName(frontend) called at [app/code/core/Mage/Core/Model/Session/Abstract/Varien.php:111]
#1  Mage_Core_Model_Session_Abstract_Varien-&gt;start(frontend) called at [app/code/core/Mage/Core/Model/Session/Abstract/Varien.php:166]
#2  Mage_Core_Model_Session_Abstract_Varien-&gt;init(core, frontend) called at [app/code/core/Mage/Core/Model/Session/Abstract.php:84]
#3  Mage_Core_Model_Session_Abstract-&gt;init(core, frontend) called at [app/code/core/Mage/Core/Model/Session.php:42]
#4  Mage_Core_Model_Session-&gt;__construct(Array ([name] =&gt; frontend)) called at [app/code/core/Mage/Core/Model/Config.php:1348]
#5  Mage_Core_Model_Config-&gt;getModelInstance(core/session, Array ([name] =&gt; frontend)) called at [app/Mage.php:462]
#6  Mage::getModel(core/session, Array ([name] =&gt; frontend)) called at [app/Mage.php:476]
#7  Mage::getSingleton(core/session, Array ([name] =&gt; frontend)) called at [app/code/core/Mage/Core/Controller/Varien/Action.php:494]
#8  Mage_Core_Controller_Varien_Action-&gt;preDispatch() called at [app/code/core/Mage/Core/Controller/Front/Action.php:64]
#9  Mage_Core_Controller_Front_Action-&gt;preDispatch() called at [app/code/core/Mage/Core/Controller/Varien/Action.php:408]
#10 Mage_Core_Controller_Varien_Action-&gt;dispatch(view) called at [app/code/core/Mage/Core/Controller/Varien/Router/Standard.php:250]
#11 Mage_Core_Controller_Varien_Router_Standard-&gt;match(Mage_Core_Controller_Request_Http Object ([] =&gt; /test.html,[] =&gt; ,[] =&gt; /test.html,[] =&gt; ,[] =&gt; ,[] =&gt; Array (),[] =&gt; catalog,[] =&gt; ,[] =&gt; Mage_Catalog,[] =&gt; ,[] =&gt; Array (),[] =&gt; Array ([0] =&gt; _GET,[1] =&gt; _POST),[] =&gt; /catalog/product/view/id/21,[] =&gt; ,[] =&gt; ,[] =&gt; catalog/product/view/id/21,[] =&gt; Array ([id] =&gt; 21),[] =&gt; ,[] =&gt; Array ([rewrite_request_path] =&gt; test.html),[] =&gt; 1,[] =&gt; catalog,[] =&gt; module,[] =&gt; product,[] =&gt; controller,[] =&gt; view,[] =&gt; action)) called at [app/code/core/Mage/Core/Controller/Varien/Front.php:176]
#12 Mage_Core_Controller_Varien_Front-&gt;dispatch() called at [app/code/core/Mage/Core/Model/App.php:354]
#13 Mage_Core_Model_App-&gt;run(Array ([scope_code] =&gt; ,[scope_type] =&gt; store,[options] =&gt; Array ())) called at [app/Mage.php:683]
#14 Mage::run(, store) called at [index.php:87]