Life as a four-dimensional cell membrane

I’m going to ask you to stretch your brains a bit and try to think of a cell membrane as a 4-d construct. Or rather, as is my point, the cell membrane.

It is easier to start by removing one dimension. Let us consider cells as enclosed 2-d shapes dividing in time.

If we use time as the third spatial dimension, the dividing cells form a closed, branching, 3-d tree structure.

Some of the cells die of their own, so some branches of the tree are just stubs. When an organism dies, that whole tree stops growing. But sometimes, happily, two of these trees make a common offshoot, and a new tree is born. Make note that the combined structure is still one closed surface.

Now let us extend our thought experiment with the remaining dimension. The closed 3-d surface of a cell membrane, moving and dividing in time, describes a single closed tree-like 4-d surface. Our brains can’t visualize 4-d objects directly, but hopefully you can logically believe that such a shape exists.

Now to the point of these gymnastics. This means that all of your cells are bound by one single 4-d cell membrane. And because offspring starts with the merging of the cell membranes of the sperm and the egg, all the cells of your ancestors are also bound by that same 4-d membrane.

Furthermore this means that all life on earth, past and present, has happened inside one single closed four-dimensional cell membrane.

The root of the tree is the first ever cell with a membrane, and the extremities of the tree are all the cells living today. In time it spans a couple of billion years, and in space it threads around the moon.

Trippy, eh?

(note: of course there are important things happening in the extracellular space in an organism, for example in synapses, but let’s not get hung up on that)