There seems to be a limit to how big or tiny life can be.
We can only exist at a special scale where the universe interacts with itself.
Life happens in the narrow band between the extremes of galactic super-structures and Planckian indeterminacy.
We can only impact the universe in scales near to our own.
It leaves one with awe to consider we exist in the special range where reality comes to know itself.
The biggest organization of matter and energy we know of are galactic super-structures.
|Galactic super structures as detected and described|
Formed by a newly discovered, but not understood “dark energy”, these collections of galaxies are at 3,000,000,000,000,000,000,000 miles long (21 zeros) and 90,000,000,000,000,000,000 miles thick (19 zeros).
At this largest known scale, the galaxies appear grouped together like the skin of soap bubbles in the kitchen sink.
Great voids of cold, empty darkness fill space between films of galaxies. These voids are not truly empty, rather sparse compared to the concentration of galactic bubble skins.
There may be larger structures than these; we are still in the process of discovery.
There are physical limits to how far we will be able to sense because of the speed of light. We may never be able know the true formation beyond a certain scale.
|Two imaginings of Planck Scale quantum foam|
The smallest organization of matter and energy we know is at the Planck Length.
Sometimes called space-time foam, the Planck length is where energy and matter can be no smaller.
The rules we know through math suggest the Planck Length is the very fabric of reality.
Only 0.0000000000000000000000000000000000636 inches across (34 zeros), these size scales are so small we can not even measure its existence, rather only guess using formula.
Here matter and energy also vibrate in a foamy like way.
Some suggest that this is the scale were bits of matter and energy form. Others speculate the universe vibrates at this level giving rise to matter and energy.
There may be smaller structures than the Planck Length.
Beyond Planck scales, reality as we know it makes no sense. It appears as if the essence of reality itself is bubbling in and out of existence at this tiniest of scales.
|Humans in the |
middle of scale
The Great In-between
Almost exactly in the middle of the scale, life exist.
Larger structures are too separated by space to have enough effect on each other to develop complex systems like life.
Smaller structures are also too separated to be able to have the intricacy needed in order for life to exist.
Only from the largest of whales to tiniest of microbes does there exists enough interaction of matter and energy for life to form.
|A hundred pennies|
Measuring Scale by Hundreds
Before we can understand how is big and how small is small, lets review some simple math.
Think about a hundred pennies.
A hundred pennies is something most people count at one time or another. A hundred is number we know.
|Scaling in hundreds|
Using units of one hundred is something our minds can grasp. We can see a hundred items and have a sense of just how many that is.
Going from one to a hundred pennies is the same scale as going from a hundred to ten thousand pennies ($100).
Going from ten thousand to a million pennies ($10,000) is another simple jump in scale.
The same kind of scaling works in the opposite direction. Imagining a hundredth of a meter is not so hard to visualize.
Imagining another step down to ten thousands of a meter is a similar leap of mind.
We will use this scale of 100’s to help us understand our scale in the universe.
Each of the dotted lines will represents a jump in a hundred times of size. Going to the left we get bigger, going to the right we get smaller.
The scale between a human and a pyramid is similar to a mosquito to a human. These jumps of up one hundred and down one hundred can be used as a reference point for how big each leap we will make.
As we go up the scale, a mountain is to a pyramid as a pyramid is to a human. Each dotted line represents a hundred times bigger.
Going up from human to moon, from moon to the solar system and beyond, we can begin to understand the enormity of it all.
The planets and stars interact with one another. They are too far apart to form life in any way that we could understand.
The forces are so far apart and the time taken to interact so long that highly complex structures simply can not form.
As long as humans only used their eyes, they could not even know how the solar system was formed. Only when they began to use telescopes did it shape start to be understood.
With larger and more powerful telescopes like the Hubble and others we have begun to probe far beyond what we knew before.
Amazing structures that slowly form and fade at large scale surprise us and inform us. Several different measurements indicate that the largest structures have taken about 16,000,000,000 (9 zeros) years to form.
As we go down the scale, a hair width is to a mosquito as a mosquito is to a human. Each dotted line represents a hundred times smaller.
Going down from human to DNA, life exists on four steps on our scale. DNA is .000000001 (seven zeros) smaller than us.
Beyond this point, the universe again becomes sparse.
The matter and energy that make up atoms are so far apart that their interactions do not permit complex things like life to form.
The smallest thing we can see is about the diameter of a hair. Beyond that scale our naked eyes fail to discern.
With microscopes we began to see the smaller. Moving from light to electrons we seek to understand the tiniest of things.
Even these tools have limits to how small we can see. Indirect evidence and experiment lead us to theories about what actually is below smaller scales.
As recently as 1900, humankind only interacted with scales between mountains and hairs. Things a thousand times bigger or smaller than us were only imagined or indirectly sensed.
|Atom bombs and atoms moved|
Einstein, Goddard, and Crick invented ideas and tools that extended our knowledge to the larger and the smaller. By 1970 humans had reached the moon and begun to understand the structure of DNA.
Our tools have only recently in human history had the ability to move mountains. With the advent of the atom bomb, we have just now been able to effect reality on the 10,000 scale.
Our tools have only just allowed us to move individual atoms around. We now manipulate DNA and other small molecules regularly.
Tools that change the universe on larger scales require enormous energy, often out of control. There may be limits to how much energy we can control.
Tools that change the universe on smaller scales require precise control and much less energy. There may be limits on how accurate we can be.
If we think about the scaling of things in the universe, it helps to understand the enormity and tininess of it all:
Galaxies are to stars as stars are to earth.
The moon is to a mountain as a mountain is to an human.
A human is to a hair as a cell is to DNA.
Cells are to atoms as atoms are to electrons.
At each scale, different structures, different organizations of the universe exist. The relationships between the scales give rise to the structure itself. The largest galactic cluster is composed of reality on the Planck level.
Limits of Scale
Perhaps someday in the not too distant future, humans will move regularly through our solar system. It does not seem impossible that we may even manipulate the parts of the atom.
There do appear to be physical limits in both directions, large and small, that will slow down our understanding and our impact on the universe.
It is wonderful to live in times of great discovery. It may be tragic to not have lived after them.
Note: If you want to explore the scale of humans to the universe, there is a wonderful online program developed by Cary and Michael Huang. This tool allows you zoom in and out at different scales, seeing graphically the relationships between Planck length and observable universe. I encourage you to spend time with this tool and learn just where humans fit in the scale of the universe. http://htwins.net/scale2/