The Energy in You
Even though it's an inexorable part of life, for many people, death — or at least the thought of ceasing to exist forever — can be a scary thing. The disturbing things that happen to the body during decomposition — the process by which cells and tissues begin to break down post mortem — are bad enough.
But what if instead of looking at death from a biological perspective, we examine it from a physics standpoint? More specifically, let's look at how our energy is redistributed after we die.
In life, the human body comprises matter and energy. That energy is both electrical (impulses and signals) and chemical (reactions). The same can be said about plants, which are powered by photosynthesis, a process that allows them to generate energy from sunlight.
The process of energy generation is much more complex in humans, though. Remarkably, at any given moment, roughly 20 watts of energy course through your body — enough to power a light bulb — and this energy is acquired in a plethora of ways. Mostly, we get it through the consumption of food, which gives us chemical energy. That chemical energy is then transformed into kinetic energy that is ultimately used to power our muscles.
A Changed State
As we know through thermodynamics, energy cannot be created nor destroyed. It simply changes states. The total amount of energy in an isolated system does not, cannot, change. And thanks to Einstein, we also know that matter and energy are two rungs on the same ladder.
The universe as a whole is closed. However, human bodies (and other ecosystems) are not closed — they're open systems. We exchange energy with our surroundings. We can gain energy (again, through chemical processes), and we can lose it (by expelling waste or emitting heat).
In death, the collection of atoms of which you are composed (a universe within the universe) are repurposed. Those atoms and that energy, which originated during the Big Bang, will always be around. Therefore, your "light," that is, the essence of your energy — not to be confused with your actual consciousness — will continue to echo throughout space until the end of time.
If nothing else can assuage some of the fear of death, the below advice from physicist Aaron Freemen via NPR should do it:
You want a physicist to speak at your funeral. You want the physicist to talk to your grieving family about the conservation of energy, so they will understand that your energy has not died. You want the physicist to remind your sobbing mother about the first law of thermodynamics; that no energy gets created in the universe, and none is destroyed.
You want your mother to know that all your energy, every vibration, every Btu of heat, every wave of every particle that was her beloved child remains with her in this world. You want the physicist to tell your weeping father that amid energies of the cosmos, you gave as good as you got.
And at one point you'd hope that the physicist would step down from the pulpit and walk to your brokenhearted spouse there in the pew and tell him that all the photons that ever bounced off your face, all the particles whose paths were interrupted by your smile, by the touch of your hair, hundreds of trillions of particles, have raced off like children, their ways forever changed by you.
And as your widow rocks in the arms of a loving family, may the physicist let her know that all the photons that bounced from you 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.
You can hope your family will examine the evidence and satisfy themselves that the science is sound and that they'll be comforted to know your energy's still around. According to the law of the conservation of energy, not a bit of you is gone; you're just less orderly.