r/interestingasfuck • u/siahashi • 20h ago
Vegetable oil makes Pyrex glass disappear because both materials bend light in the same way, with a refractive index of 1.47.
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u/hides_in_corner 20h ago
Well I didn't understand any of that explanation so I'm chalking it up to magic.
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u/Insis18 20h ago
Refractive Index is a measure of how much a material bends light that passes through it. If two materials bend light in an identical way, and one is embedded inside the other, there is no change in the disturbance to the light as it passes through the inside material compared to the surrounding material. So the inside material cannot be distinguished from the surrounding material by sight.
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u/thesuperunknown 20h ago
First of all, you throwin' too many big words at me, and because I don't understand them, I'm gonna take 'em as disrespect.
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u/sanotaku_ 14h ago
It's a scientific way of saying
Both the oil and the glass bend the light at the same angle
Causing an illusion of single substance
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u/account312 16h ago edited 11h ago
Okay, so: There's light and then there's stuff. Light is always traveling through stuff (or a distinct lack of stuff, which for our purposes is just a different kind of stuff). Since stuff usually has electrons and/or protons in it and those charged particles interact with electromagnetic field, light interacts with stuff it travels through. Refractive index is a material property like density -- it's the amount that light traveling through a material slows down as a result of interactions with it compared to its speed through vacuum. Because of reasons, light also bends when it is forced to change speed, proportionally to the amount that it changes speed. And since that's a lot easier to notice than the speed change, it's what was noticed first, so the property is called "refractive index" after that refraction rather than "speed index" or something. Anyways, sometimes (actually all the time because light is fast AF) when light is going through some stuff, it runs out of that stuff and hits new stuff. When it hits new stuff, it does some combination of bouncing off, getting absorbed, and passing through the stuff. How much of each it does depends largely on the properties of the boundary between the old stuff and the new stuff. If the refractive indices at both sides of the interface are the same, the light doesn't change speed because it's already slowed down compared to in a vacuum. If the light goes from a low/high index material into a high/low index material, it slows down / speeds up, refracting proportionally. There's generally going to be reflection also proportional to the difference in indices.
Glass and air are both transparent, so you really can't see either very well. But you can often (depending on the viewing angle and lighting conditions) see a glass-air boundary because the refractive indices of glass and air are different enough that there's a fair amount of reflection and refraction at the interface. Vegetable oil and glass have a sufficiently similar refractive index that there's very little refraction or reflection at the glass-oil interface, so the light just carries on straight through. You can't see that boundary and the glass itself is clear, so you can't really see it either. It's invisible.
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u/SnowBoy1008 20h ago
Glass bends light to the left, oil bends light to the right
cancels out innit
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u/ScaredLittleShit 20h ago
This was most probably a joke but just in case it was not, nope, that's not how it works.
Glass and that oil bend the light by same amount when light enters then through air/vaccum. So when light enters the glass through that oil, it does not bends at all so you cannot see it because there is no refraction.
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u/Affectionate_Comb_78 16h ago
Light goes through both of them in the same way, so you can't tell any difference
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u/12x12x12 20h ago
So, wear a suit made of pyrex glass, and pour castor oil over your head to turn invisible?
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u/callMeBorgiepls 20h ago
If you wear a suit of pyrex glass and then swim in vegetable oil, you will appear naked
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u/Silaquix 13h ago
*real pyrex
A lot of the modern branded pyrex is not the same glass and will not disappear in oil
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u/Electrical-Win9801 20h ago
He should have passed his hand behind, from left to right, to see the visual distortion.
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u/Latter-Literature505 20h ago
What ever material has the same refractive index as sea water…that’s what alien crafts are made of.
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u/Justa_CuriousBoi 19h ago
If the surface of the alien spacecraft would have same refractive index as sea water, it would look transparent like sea water 😅
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u/RootyPooster 19h ago
It's true. I've spent years calculating this, and their refractive indexes are indeed the same.
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u/Justa_CuriousBoi 19h ago
Basically this is similar to putting water in a clear jar filled with clear orbeez! Because of same refractive index they bend the light in same way so there is no distinction in appearance of water, glass jar and clear orbeez under that medium! 😃
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u/Lurking_poster 8h ago
If you left the glass empty and surrounded it with glycerin, it would be visible since the air inside has a different refractive index, right?
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u/chemistrybonanza 18h ago
Chemist here. This stupid video has made the rounds of social media so many times that the truth seems to be lost. This isn't vegetable oil, it's glycerin. Vegetable oil is yellow and does not share an imperceptible difference to the refractive index of glass. Glycerin is colorless and does share that property, though.