epic science facts

All of the atoms in your body are constantly being renewed and the ones you were born with are no longer a part of you. Your atoms are probably spread all around the planet right now, especially the ones you have breathed in or out.
You have most likely breathed an oxygen atom that Einstein (or any other person really) breathed while writing his famous equation.  Of course those atoms would have to still be on Earth for that, so if they all got struck by cosmic rays and were blasted off into space, then you are out of luck. But hey if that is the case, then you are breathing a proton sent from across the galaxy!
Though in a way, all of the atoms here were sent from across the universe, considering every element outside of Hydrogen was birthed in the core of a star at some point. Then those stars had to explode to spread their atoms elsewhere, which eventually came together in a momentary flow to create you.

That is right, we are on a collision course with our neighbor, the Andromeda galaxy.

We are hurtling towards each other at 250,000mph, though considering the size of each galaxy and the distance between them that is basically a stand-still. In about 4 billion years however you can expect the sky to be very different as the Andromeda galaxy gets closer and eventually collides with the Milky Way. The Earth (and almost every solar system) will be fine, because there is just so much interstellar space for everything to pass right by. The interstellar gas will collide however and start new star formation, this will be noticeable in the sky as all of the new giant-balls-of-hydrogen (i.e. stars) begin to ignite. Eventually, the cores of each galaxy will merge and dominate the night sky.
See the entire process here via Science at NASA