I was listening to radiolab and they mentioned that bacteria are usually 100s of times bigger than viruses. I’ve never really had a good sense of the relative sizes of microscopic things, but always wanted to.
So if a virus was human sized, would a bacteria be building-sized? Would an atom be the size of a penny? Basically, if you were to map the microscopic world onto the visible world, what would things be?
In: Biology
The Covid-19 us looks to be around 80-120nm in diameter, let’s call it 100 nm
Look at [https://en.wikipedia.org/wiki/Atomic_radii_of_the_elements_(data_page)#/media/File:Atomic_radii_up_to_zinc.png](https://en.wikipedia.org/wiki/Atomic_radii_of_the_elements_(data_page)#/media/File:Atomic_radii_up_to_zinc.png) for atomic radius, the area from around 50 to 250 pm so a diameter of 100 to 500 pm
1 nm = 1000 pm so the atomic diameter is around 0.1 to 0.5 nanometers.
So a Covid-19 virus is in the order of 1000 to 200 atoms in diameter depending on which atom you look at.
Atoms: 0.1 nanometers.
Viruses: 100 nanometers.
Bacteria: 10,000 nanometers.
So if virus was human-sized, a bacterium would be skyscraper sized, and an atom would be ant sized. Since everything is made of atoms, at that scale you WOULD see the atom “building blocks” of everything; objects would look like they’re made of [ant-sized balls](https://i.pinimg.com/originals/0b/03/68/0b0368f4d6e909a6c0d31c4bfb07c7cc.gif) / [pixelated](https://mae.princeton.edu/sites/default/files/styles/large_scaled/public/2023-07/atoms%20with%20labels.jpg?itok=l2wYFPaW) like in Minecraft.
Depends on the atom if we really want to be pedantic, but I won’t go that far (someone else may).
Depends on which virus and which bacteria, too, both have quite a wide range depending on the species/group.
But yes – roughly put, if a virus were human sized you could conceivably have some bacteria that might be the size of an average house or small apartment building. A virus is, basically, a coil of genetic material (RNA or DNA) with a shell around it. A bacteria has a whole suite of tiny organ-like features inside it, one of which is its own coil of DNA but others do things like metabolism, respiration, moving nutrients around, etc. Bacteria range in size just the same as birds do. Imagine a hummingbird as compared to an eagle or a swan, bacteria follow a similar range of sizes (just at a much smaller scale). Viruses do, too, but their larger sizes are much rarer. The very largest viruses are about as large as the very smallest bacteria, but where bacteria count in the hundreds or thousands of types at this scale, viruses only have a handful of extra-large ‘species’.
In real life, most bacteria are visible under a microscope like you might use in gradeschool or highschool, a virus is not. A virus is quite tiny by comparison, and except for the largest ones mentioned you can’t see them under a microscope. This is part of what makes viral diseases like COVID so difficult, you can’t just check them out under a microscope. You need highly specialized equipment, and even then you are often limited to inferences and eliminating possibilities as opposed to direct observation. There are a few micrscopes that can resolve a virus but these are … that’s another story.
On the imaginary scale an atom would still be vanishingly tiny, however. Even a simple virus can contain millions of atoms in its constituent molecules. If a virus was the size of a human, an atom may still be microscopic. Atoms are *really* tiny. An atom compared to a virus would be smaller than a brick compared to a skyscraper. It’s an interesting question, let’s see if someone does the math.
Here’s some useful images to illustrate relative scales:
[This is an atomic render of a coronavirus](https://en.wikipedia.org/wiki/Coronavirus#/media/File%3ACoronavirus._SARS-CoV-2.png). Each of those little fuzzy looking spheres that the virus is made of is an atom.
[This is a comparison between a coronavirus, a bacteria, and some other types of cell](https://abcdust.net/how-large-is-a-corona-virus-virion-compared-to-the-mp10-2-5/)
There’s a great video by Epic Spaceman on YouTube that does an awesome job illustrating the scale of the very small.
[Link](https://youtu.be/rn9dkV4sVYQ?feature=shared)
this might also help conceptualise the sizes. A bacteria is a single cell, a virus works inside cells on the DNA/RNA so it is small enough to be inside the cell and multiply many times in there. That’s what makes it hard to counter viruses as they’re hidden inside cells. And lastly atoms are the building blocks for elements, and these are made up from subatomic particles (positive, negative and neutral) that determines which one they are
Part of the struggle is that atoms are so small that the wavelength of light makes it impossible to directly observe them with our eyes. So we are stuck with a perception of size based on our own experiences but that doesn’t necessarily relate to the size of atomic structures. The best we have been able to do with visualizing atoms is by tracing them out. Things get more strange when you consider the structure of an atom, atoms are mostly empty space, which sounds asinine when you consider everything we think of as matter is made up of these things. Take the simplest isotope of hydrogen, if the proton (so 1 proton 1 electron [protium] vs 1 proton 1 neutron 1 electron [deutron]) is the size of a basketball then the electron orbits **two miles away**.
So, suffice to say, the size difference between anything observable through a microscope and an atom is very large. An atom is .1 nanometer, a virus is 100 nanometers, from the magic of the metric system we can deduce that a virus is 1000 times larger than an atom. I am about 2 meters tall, so if I am an atom then the virus would be 2000 meters. That is very nearly the height of some rocky mountains if I am standing on the high plain directly adjacent to them.
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