- var_dump: documentation ( source)
<?php
$amsterdam = new DateTime('now', new DateTimeZone('Europe/Amsterdam'));
$amsterdamTimestamp = $amsterdam->getTimestamp();
$newYork = new DateTime('now', new DateTimeZone('America/New_York'));
$newYorkTimestamp = $newYork->getTimestamp();
var_dump($amsterdamTimestamp, $newYorkTimestamp, $amsterdamTimestamp - $newYorkTimestamp);