Some time ago, my labmates and I invented a character named “Nano Person” as a way of giving some frame of reference for the nano-scale. Nano Person fights nano-crime as well as societal biases and restrictive mindsets, but that’s a digression for another blog post. This thought experiment got me wondering, what would the world look like for Nano Person? What would their experience be like?
What better way to learn about someone’s experience than to take a walk in their shoes? Determined to find out more about Nano Person’s perspective, I contacted members of the Murphy lab at the University of Illinois-Urbana Champaign (experts in synthesis of nanomaterials) to synthesize a nano-body for me. Sort of like Ant-Man, this suit would allow me to shrink down to a small enough size so that I could explore the nano world. They told me that, not only does the technology for any part of that not exist, but a human shrunk down that small would surely not survive the experience (For an informative, but perhaps graphic, discussion of why this might not work, check out this video from Kurzgesagt – parental supervision recommended for young viewers). Anyway, I figured we could reason our way through the idea and imagine what the nano world would look like to Nano Person. Since this is my imagination, we will call this very tiny human Nano Zack.
I’m about 6 feet (1.8 m) tall, about 1.5 ft (0.46 m) across and weigh about 150 lbs (68 kg). So, if I were to shrink down to 100 nm at my desk, I would be 100 nm tall and about 25 nm across. Since we know that humans just barely float in water we can guess that we have a density pretty close to that of water (1000 kg/m3), so since my weight is about 70 kg, my volume must be about 0.07 m3. Assuming my height and weight are proportional, at the nanoscale I might weigh around 4 micrograms. There are some issues here in assuming that my mass is changing associated with the laws of mass conservation but this is a bit of a no-win. Without getting into too much detail, we’d have to choose between a catastrophic sudden release of energy (think like, a lot of nuclear bombs), or keeping all of my mass and becoming uncomfortably dense. So we’ll just gloss over that part.
With my new 100nm height, the first thing that I would encounter may be the wood of my desk. Now, this wood feels somewhat textured to my fingers at normal size, so for Nano Zack this texture would be like staring at a mountain range from sea level. If we consult electron microscope images of common woods, we can see the presence of pores up to around 500 micrometers in size. That’s 5000x Nano Zack’s height, which is comparable to my experience as a 6-foot tall person gazing across a pit that’s 5 miles across. (For comparison, the Grand Canyon is 4-18 miles wide.) So, if I’m lucky enough to end up on the edge of one of these pores instead of within one, I can make my way toward the edge of my desk. This may take some time.
Along the way I will likely encounter some things that are kind of weird and kind of gross, like bacteria and skin cells. It’s highly likely that my desk has a lot of old skin cells laying around, as we lose ~500 million skin cells every day,1 and I spend a lot of time at my desk. Human skin cells are about 30 micrometers (30,000 nm) across, or 300 times Nano Zack’s size, and weigh about 2.5 ng. They are about 2 micrometers tall which is 20x taller than Nano Zack, so as I stand at the base of one, I feel like regular-sized-me is looking at a 12 story building. I’ll walk another direction. As I turn around I encounter the bacterium Escherichia coli, which is around two micrometers long, and half a micrometer (or 500 nm) wide, so it only looks like a 3-story building. Pretty spooky. In truth I’m more likely to find Streptococcus on my desk,2 but since we’re using our imagination we see E-Coli.
It is at this point in my journey, as I’m confronted by the horrors of a terrifying new landscape with mountainous terrain and micro-beasts, that I start to feel pretty on edge. I long for the reality that I once knew where I couldn’t be crushed by a falling dust particle. Nervous and exhausted from traversing my desk, I come across a cold virus that normal-sized Zack has been battling for a week. A rhinovirus is only around 30 nm wide (Rhinovirus) and is commonly known as a real jerk (citation not found). As I stand facing the virus, a bead of sweat forms and falls down my brow; I notice my hands shaking. I’m thinking about all the colds that I’ve had in my life, the days of school and work missed, the sniffles . . . sniffled. The virus stands across from me, cold, unfeeling; it doesn’t think about anything — it’s a virus. It’s a high-noon showdown now. Me and the virus; the virus and me. This desk ain’t big enough for the two of us. Okay well I guess it’s plenty big for both of us, and I don’t really want to mess with The Cold anyway.
In order to make a speedy getaway and avoid an unnecessary encounter with the virus, I decide to hitch a ride on my old pal E. Coli, whom I met earlier. I scale the side and light out for the edge of my desk. Assuming we start around 1 foot away, the journey will take the two of us a few hours. That is nice, because Steve (I named the bacterium Steve) moves much faster than I could. At regular size, I walk around 3 mph or 1.3 m/s, so I can move roughly my own height in 1 second. Working out the math, making this nano-scale journey on foot would take me over a month! Luckily, I have a ride who moves at about 30 micrometers per second (about 15x its length every second)! So instead of 34 days we might get there in 3 hours. Thank goodness.
When we’ve reached the edge, I contemplate the strange environment I just explored as I peer over a 3 foot – or 900 million nanometer – drop. That’s nine million times my height as nano-Zack, which is comparable to a 10,227 mile distance for 6 ft tall me. For reference, the distance from New York City to Los Angeles is about 2,500 miles, and literally halfway around the world is about 12,000 miles (Wolfram Alpha). That’s too scary for me. Having seen the nanoscale terrain that makes up the surface of my desk, I think I’ll leave the nano-exploring to Nano Person and just use electron microscopes from now on.
ADDITIONAL RESOURCES
- Wolfram Alpha: www.wolframalpha.com/
- Cell size & scale interactive animation: learn.genetics.utah.edu/content/cells/scale/
- For more about other adventures of nanoscale (and microscale) people, check out some episodes of The Magic School Bus on Netflix
REFERENCES
- Weschler, C. J.; Langer, S.; Fischer, A.; Bekö, G.; Toftum, J.; Clausen, G. Squalene and Cholesterol in Dust from Danish Homes and Daycare Centers. Environ. Sci. Technol. 2011, 45 (9), 3872–3879. DOI: 10.1021/es103894r
- Meadow, J. F.; Altrichter, A. E.; Kembel, S. W.; Moriyama, M.; O’Connor, T. K.; Womack, A. M.; Brown, G. Z.; Green, J. L.; Bohannan, B. J. M. Bacterial Communities on Classroom Surfaces Vary with Human Contact. Microbiome 2014, 2 (1), 7. DOI: 10.1186/2049-2618-2-7
Sustainable Nano 