Let me introduce you to the Law of the Conservation of Energy. This Law will be my eulogy. I want my grieving family to hear about this Law, so they will know my energy has not died. I want them to learn about the First Law of Thermodynamics; that no energy gets created in the universe, and none is destroyed. I want them to hear that all my energy, every vibration, every Btu of heat, every wave of every particle that was me remains with them in this world. I want them know that amid energies of the cosmos, I gave as good as I got.
The speaker can talk to my spouse and tell her that all the photons that ever bounced off my face, all the particles whose paths were interrupted by my smile, by the touch of my hair, hundreds of trillions of particles, have raced off like children, their ways forever changed by me. And as my widow rocks in the arms of my loving family, the speaker will let her know that all the photons that bounced from me were gathered in the particle detectors that are her eyes, that those photons created within her constellations of electromagnetically charged neurons whose energy will go on forever.
They will explain that this is something that requires no faith in any god, Christian or otherwise. That humankind can measure this, that scientists have measured precisely the conservation of energy and found it accurate, verifiable and consistent across space and time. I hope my family will examine the evidence and satisfy themselves that the science is sound. I hope that they'll be comforted to know my energy is still around. According to the Law of the Conservation of Energy, not a bit of me will be gone; I'll just be less orderly.