Wordpress - fetch user info using jQuery ajax POST request
===

I am working in Wordpress trying to use an ajax request to fetch user data by passing the user id.

I can see that the user id sends correctly via AJAX POST but I am getting an internal error message and I don't know why.

At first I thought it was because I was trying to fetch some custom fields that I had added to the user profile but even when I simplified my script I am still getting the error message.

Any help is much appreciated!


__Front End__

    $('.author').click(function() {
        
		var id   = $(this).attr('id');
		var temp = id.split('-');
		id = temp[1];
		
		$.ajax({
                type: 'POST',
                url: 'wp-content/themes/twentyeleven/author_info.php',
                data: {id: id},
				dataType: 'html',
                success: function(data) {
				    $('#author-bio').html(data);		
				}
            });		
		
        return false;
    });


__author_info.php__

    $user_id = $_POST['id'];
	$forename = get_the_author_meta('user_firstname', $user_id);
	$output = $user_id;
    echo $output;

__Error Message__

`500 (Internal Server Error) jquery.min.js:4`