Everything is being jostled around randomly. The molecules don't have brains or seeker warheads. They can't "decide" to home in on a target.
The only mechanisms for guidance are: diffusion due to concentration gradients, movement of charged molecules due to electric fields, and molecules actually grabbing other molecules.
It's all probabilities. This conformation makes it more likely that this thing will stick to this other thing. You may have heard that genes can be turned on or off. How? DNA is literally wound on molecular spools in your cell nuclei. When the DNA is loosely wound other molecules can bump into it and transcribe it -- the gene is ON. When the DNA is tightly spooled, other molecules can't get in there and the gene is OFF for transcription. There's no binary switch, just likelihoods.
Everything is probabilistic, but the probabilities have been tuned by evolution through natural selection to deliver a system that works well enough.
In the context of Covid19, I see so many people wearing PPE, but failing to act as though they understand that the actual goal is to prevent this tiny virion dust from entering your orifices. Like wearing gloves and a mask, but then picking up unclean item in store then using now unclean gloves to adjust mask and make it unclean.
People seem to think of things as having essences or talismanic effects. Like gloves give you +2 against covid and a mask gives you +5 when it's really all about preventing those virus things from bumping into your cell things.
Masks are for keeping your own particles from spreading far AND for lowering the probability of virions found in the environment from entering your respiratory system.
Masks lower the probability when all other variables are held constant. If someone thinks wearing a mask grants invincibility and in turn chooses to increase their exposure to high viral load individuals or environments, they're putting themselves at risk.
Both of you may be correct. I think the person you responded to may not have been precise in their framing.
I suspect that you had N95 masks in mind when you wrote masks, which doesn’t negate the point of the person you responded to, if they had surgical masks in mind when they wrote masks. Surgical masks are far more common than N95 masks since they are cheaper and do not provide protection against viral particles for the wearer.
https://smartairfilters.com/en/blog/n95-mask-surgical-preven... https://smartairfilters.com/en/blog/coronavirus-pollution-ma...
What that image drove home for me is:
1) that DNA transcription isn't something that happens rarely, or once-at-a-time. DNA is constantly being transcribed; proteins are constantly being built. The scale and rate isn't something I'd ever been taught.
2) How RNA polymerase works must be taking into account a hell of a lot of congestion. Polymerase molecules must constantly be bumping into each other.
3) How the picture would make no sense whatsoever unless you already know what the mechanism is.
I think it does make sense to start with the idealised process, as long as you follow up with messy reality.
To clarify: a "point particle" is an object with no internal structure, that is, it can be fully described by its coordinates wrt time (ignoring relativity for now). This is a concept, a model which explains many phenomena, a model on top of which you can build many theories. It does not, however, explain the conjunction of QM with special relativity.
I'm in Taiwan where masks are ubiquitous, and have been upset reading about the slow adoption of masks in the West because it was always from a selfish perspective ("do masks protect ME?") whereas here they're worn for a communal purpose ("how do I protect others?"). How effective they are at blocking incoming infection always seemed like a big distraction to me, since it's been clear from the start that it reduces spray from spreaders talking and coughing, which alone is enough of a reason to adopt it widely.
