Essay 8 04/16/04: Astrophysics, Photosynthesis, Cognitive Processing
Understanding Sunlight
Ultimately the energy for all thought, including the energy required to read an essay, comes from the sun.
Plants transform solar energy into chemical energy through the process of photosynthesis.
Chloroplasts inside the plant's cells use this chemical energy to create energetic bonds between water
molecules from the ground and carbon dioxide molecules from the air to create plant matter: living,
breathing cells.
We as humans ultimately gain both all of our mass and all of our energy from plants. Just as plants are
constructed from carbon and water- so are we. From our earliest of developmental stages, all of the
mass that our genetic material acquired came from plants or from a form of life that fed on plants. But
we get more from photosynthesis than just the molecules that we need to grow and maintain our
bodies, we also get the energy that we need to live and move.
After you eat plant or animal remains many of the chemical bonds that exist in the matter that you
consume are broken down within your cells. Energy that initially came from the sun (that enabled the
creation of the chemical bonds) fuels every physical activity that you engage in, including your mental
activities. Just like the cells throughout the rest of your body, the energy that the cells in your brain use is
acquired from metabolizing consumed nutrients. Therefore every thought that you engage in (including
those that you organize in order to read this page) are created by electrical and chemical energy that
initially came from the sun.
Would you ever guess that starlight and the traces of a few simple elements contained on a big rock
floating through space would interact in such an incredible fashion?
Energy from sunlight has allowed many amazing combinations of materials, one of the most amazing of
which, to me, is cellular life. Cells have the ability to react to their environment, and some groupings of
cells, (like you and I) have the ability to interact with it. The behaviors exhibited by different groupings of
cells here on earth are amazingly diverse. From ATP synthesis to cellular respiration, from animal
instinct to the writings of Shakespeare, cells exhibit phenomenal capabilities.
“The energy of the mind is the essence of life.”
-Aristotle (384-322 B.C.) Greek writer, philosopher
Photosynthesis: The process by which plants known as photoautotrophs convert the energy in
photons of light into chemical bonds between carbon, oxygen and hydrogen in order to create their
physical structure.
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