title: date_default_timezone_set() seems to have no effect
body: <p>I was trying to get the <code>time()</code> on a PHP page (localhost), but it seemed it was returning wrong dates. So I tried:</p>
  
  <pre><code>date_default_timezone_set("America/Chicago");
  echo "America/Chicago:".time();
  echo "&lt;br&gt;";
  
  date_default_timezone_set("Europe/Helsinki");
  echo "Europe/Helsinki:".time();
  </code></pre>
  
  <p>Which outputs:</p>
  
  <pre><code>America/Chicago:1439981623
  Europe/Helsinki:1439981623
  </code></pre>
  
  <p>How is it that these two values are the same? How can I make sure this particular php-page returns times in my timezone, without changing the php.ini file?</p>