Proof that I'm immortal

[Aegon]

The first law of thermodynamics states that energy can neither be created or destroyed.

Since my body is a collection of atoms, and atoms are energy, then the energy that comprises me has always existed and always will.

I realize that the same argument could be made for a rock, but since I'm thinking about it and the rock isn't it seems significant. 

What do you think?

I definitely understand where you're coming from with this. The idea that we've all deluded ourselves into thinking we are distinct from everything around us. We cut and classify our surroundings into little bits and pieces, all of which we feel we are separate from, or even above. When you remove that egotistical thinking, and realize you are no different than the things you surround yourself with, it's both humbling and rewarding. I love the feeling. Some find it scary, since they think with their ego and hyperfocus on their "insignificance" compared to the grand size and age of the universe. They need to realize that "significance" is one of many concepts that aren't real outside of human experience. Nothing is inherently significant, things only gain significance when we put the label on it. The mere idea of significance doesn't make sense when you think outside of yourself. Neither does concepts like chaos, randomness, order, etc. Which is why I always find it particularly silly when a theist may argue, "But how did the universe come to be? Randomness!? With no God, everything is chaos!" The universe has existed for 13 billion years and you're saying it's not allowed to make sense until your stupid ego can make sense of it by interjecting obviously man-made deities? We can't fathom things just happening? Everything has to be nice and orderly and reasonable and reasoned to us, and we can't wrap our minds around that fact. We're just a part of things, not above them, no matter how intelligent we are. We live in a cycle of life and death like anything else in nature. Nothing separates us from our surroundings other than our ego, which is an incredible thing but also tends to curse us into holding a massive misunderstanding of the world around us, which generally results in religious belief and superstitions. 

I would not say that we are immortal though. When thinking of ourselves purely in terms of energy, you're right. It's healthy to think about that sometimes, for the reasons mentioned above. The ego is what creates our identity. Obviously, that ceases to exist upon death. I'd argue that, while we are not immortal,  we experience immortality... if you make the assumption, as the majority of us here do, that you cease to exist upon death. We know we're not immortal because we see death happen in real time, but we will never truly experience our own death. Let's hope the dying part isn't too bad though...