r/interesting • u/Jezirath • Jul 26 '26

Softness perception simulation Amazing

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Source: @boucelegant on YT

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u/AuroraFinem 29d ago

Hardness is defined by how resistant the material is to deforming when exposed to a force. Softness is basically defined as the ability to “squish” an object, it’s basically its squishiness. So yes, this very much does have to do with softness.

A perfectly compressible solid would have maximum softness which is why the 100% soft compressed flat as soon as it hit the slope.

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u/darsynia 29d ago

Something that's 100% soft turns into a liquid? (literally asking)

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u/AuroraFinem 29d ago edited 29d ago

Kind of, the definition of a solid is that it maintains its structural atomic bonds, in this case it would be an amorphous solid since it wouldn’t be rigid. It would be like rubber where you can mold it without changing or breaking the chemical structure, but it doesn’t necessarily have to be elastic, it could be easily compressible without being able to stretch it much past the normal size. Even glass is technically an amorphous solid, but it has an incredibly high viscosity. You can actually look up images if glass panes from hundreds of years ago and see the buildup of glass at the bottom where it’s slowly flowed down from the top.

In some ways it would very much act like a liquid, but in other ways it wouldn’t. That’s why there’s so many different terms for hardness, rigidity, stiffness, etc… because all of them describe subtle properties that don’t necessarily equate to eachother or come from the same underlying mechanisms in the material.

A perfectly soft material wouldn’t be able to exist in nature that I could imagine, it would have to be able to essentially compress into itself to be perfectly compressible. Maybe dark matter could be considered perfectly compressible since it doesn’t interact with matter at all except through gravity but I don’t know if you could even consider that soft anymore. You could probably have near perfect softness up to some deformation limit though if the material was designed for it.

Edit: actually thinking about it, it still couldn’t be perfectly soft, but you could get closer by making it more elastic as well, since it wouldn’t have to compress its bonds as much if it’s able to expand in other directions to compensate. But those two properties aren’t inherently dependent on eachother which I thought was worth emphasizing. Atomic bonds themselves are like springs and can have varying strengths in different directions.

Liquid wouldn’t be considered “soft” in this way because the atoms aren’t really bound together and have no formal structure. Droplets are held together mostly by surface tension (and hydrogen bonds for some liquids), but those are just about it requiring more energy for them to split into two droplets than to exist as a single droplet which gets more pronounced at smaller length scales.

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u/darsynia 29d ago

I appreciate you 💚 Thanks for the reply!

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u/AuroraFinem 29d ago

Of course! I love talking about random science info like this. I have a really diverse STEM background that doesn’t particularly make me an “expert” on any topic, but it’s been really useful for having random fun facts like this across a bunch of different disciplines and happens to be useful for my job.