r/explainlikeimfive

ELI5 How does end-to-end encryption messaging work after it reaches the end?

Edit: The question has been answered, please see from this comment onwards thank you

https://www.reddit.com/r/explainlikeimfive/comments/1tjo6cs/comment/on2u11n/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

I'm familiar with public key encryption at the very simplest level. The idea is data should be inaccessible to anyone but the intended recipient, even to those systems that send the data.

But that applies to transmission. Once the data is on the device it must be unencrypted to make it accessible to you. At that point what is to stop a service accessing that data?

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u/Old-Class-1259 — 5 hours ago

ELI5: What makes light speed constant and what changes it?

Was reading Project Hail Mary and I kind of fell into a Rabbit hole about how light works.

It is confusing to me that light speed is constant regardless of the observer, and even how that was proven mathematically. My fundamental physics classes taught me that speed is relative to the observer and that a lot of things can be measured in a lot of different ways. However, I'm aware that time dilation is a real thing and theoretically what makes it possible is the fact that light speed is constant regardless of its observer (I assume we shouldn't count light as its own observer lol).

If that is the case, are there any other subjects available in nature that have constant speed regardless of observer, or close to it?

Another observation is that photons behave slightly different on earth than in vacuum, where Light speed slows down. Same thing happens with photons submerged in water. Why can light travel slower than C depending on circumstances like gravitational pull, or being submerged in water, but still able to "catch up" maintaining its constant velocity regardless of how fast the observer is to light itself?

Thanks in advance for the help!

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u/reperete — 12 hours ago

ELI5 I'm planning to ditch Windows OS and start using other alternatives. What should I know before choosing?

I'm a casual player and my computer hardly is used for other things besides games. But all games I play are not hardware demanding and my MSI GE62 apache Pro still handles my steam games.

I need to update my OS (10th) but Windows 11 demands of new hardware specs and the cost of new parts are increasing at unfair prices.

I'm open to explore other operational systems. What are the options ahead, what should I expect, where should I start my research? There's available information but it seems to be all scattered around and I was not able to find a concise comparison between OS.

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u/EatVegetables_ok — 9 hours ago
▲ 1.6k r/explainlikeimfive+1 crossposts

ELI5: why are power lines deliberately designed to sag and what would actually happen if you pulled them perfectly straight

was driving through nevada last week, nothing but flat land and power lines for like 200 miles and i kept staring at the sag between each pole thinking it looks almost sloppy, like whoever installed them just didnt pull hard enough

but then i thought, these are massive infrastructure projects, theres no way thats an accident. so why do they actually do that and what would happen if the lines were pulled completely tight and straight

anyway the drive ended up being worth it, had some money saved up so finally did the full nevada stretch i always wanted to do

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u/Dismal-Helicopter726 — 20 hours ago
▲ 1 r/explainlikeimfive+1 crossposts

ELI5 Why does water even standing eat away everything? Metal, concrete, brick, wood, asphalt?

Why does water destroy anything in its way no matter the material? And what makes waterproofing special and behaves differently

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u/Then_Marionberry_259 — 11 hours ago

Eli5 Why can we not just build trains along highways - usa

I understand theres alot that goes into maximizing riders and all that, but is there a reason we don't just add trains onto highways medians?

I can only guess that platforms for people become a problem over such large spans, and that maintaining those would also be an issue since you still have get to the track.

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u/ManicMannequin — 18 hours ago

ELI5 Why do breast sizes differ so much depending on the band size?

Not sure how to explain it right in the title, sorry =( I measured myself to go buy some bras and I was shocked to discover I technically had D cups. I always assumed D cups were automatically huge but mine are very very average.

I did some more research and it seems like band size affects it heavily - for example, someone with a 28D cup like me is very average but 34Ds are huge!!! But what I can't wrap my head around is that it's the same difference in measurement, just 4 inches, so why does it change so much? I'd think they're the same proportionally. Is it just a perception thing???

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u/-sleepybird- — 20 hours ago

ELI5 - Investing in stocks 2026

Can someone please explain stocks. I don’t want to invest much yet but every video seems to be some promotion or someone selling a course.

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u/Lololala29 — 13 hours ago

ELI5: Why do data centers need only water for cooling? Are there no other viable cooling options?

Why do data centers need so much water for cooling? What happens to the water that goes through the data centers? Why haven't there been any better cooling options than water?

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u/5headHaroldlop — 1 day ago

ELI5: Why do we feel more exhausted and groggy after sleeping for 10-12 hours than we do after sleeping for only 6 hours?

I always thought more sleep equals more energy, but oversleeping always ruins my day. Why does our brain do this?

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u/Various_Educator_756 — 19 hours ago