You do not want to redirect, you want to create a hyperlink.
Use the built-in Html Cake helper.
In your controller ...
var $helpers = array( 'Html' );
In your opinion ...
echo $this->Html->link( 'Google link!', 'http://www.google.com/' );
Redirects are typically used to refer to a server-side redirect script. For example, after a user fills out a contact form, you can send us your details by e-mail, and then redirect the user to "Success!". pages with the following controller code
$this->redirect( '/contact/success' );
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