Oneness with the universe is a state of mind. You acquire this understanding when you develop your spiritual abilities. Discover and work with the unseen world. If you are thirsting for truth, stick around, read and learn.
Develop your spiritual identity before you need it to survive. It takes practice, first, to find the truth, then to live the truth rather than always accepting the established way of thinking and doing. Your activated spiritual nature opens a whole plethora of opportunities to know thyself. All you need is your mind to take you inside of yourself. Relax your grip on physical reality to grow in understanding and awareness of the invisible world and the universe beyond. The physical is only one aspect of your true self. You have spiritual, emotional, and psychic aspects to grow in expertise, too. Research and update your belief system. Loosen Up! Open Up! Wise Up! Live it up! This is the only life you have. Make it the best you know how.