The Hierarchy of Structure: Top-Down vs. Bottom-Up


For our Universe, there are basically two approaches to the theory of structure formation via gravitational instability – top-down and bottom-up. Top-down theories claim that the largest structures formed first, thereafter subdividing into clusters, groups, and galaxies. Bottom-up theories assert that the Universe’s primordial seeds formed protogalaxies and that these objects subsequently to together to form galaxies, groups, clusters, and so on.

My class looked at different processes and objects and tried to determine whether they followed top-down or bottom-up theories. Following is a list of what they found.


Top-down Processes

Formation of sand: boulder ® rock ® pebble ® sand

Creating a sculpture: block of clay ® pieces removed to form a shape

Making paper: trees ® logs ® smaller wood ® pulp ® paper

Decay process: corpse ® maggot ® bacteria ® protein

Buffalo wings: chicken ® wings

Composing music: score ® woodwinds, brass, strings ® flutes,

clarinets, trumpets, trombones, violins, cellos ® individual instruments


Bottom-up Processes

Formation of physical things: quarks, gluons ® protons, neutrons ®

atoms ® molecules ® objects

Formation of biological things: cell ® multicell ® organ ® organ

system ® organism

Education: K-6 ® middle school ® high school ® college ® graduate

school ® job

Computer programs: flowchart of ideas ® procedures ® modules ®


Making clothes: fibers ® thread ® fabric ® clothing

Kool Aid: sugar, water, powdered drink mix ® kool-aid drink

Snowman: snowflakes ® snow ® snowballs ® snowman


Depending on the perspective, several of these items could be made by either top-down or bottom-up processes.