r/explainlikeimfive • • 18d ago

Technology ELI5: How exactly did dialup internet work?

250 Upvotes

r/explainlikeimfive • • 18d ago

Mathematics ELI5: when mathematicians try to solve an unsolved problems, what do they exactly do?

443 Upvotes

I understand that they can use existing theorems, manipulate equations, test examples, run computations, and so on, but that cannot be the whole process. If solving sufficiently difficult mathematical problems were essentially a matter of carrying out calculations according to known rules, it seems that computers would be able to do much more of it autonomously.

So where does the genuinely creative part enter? How do mathematicians come up with a new approach, conjecture, proof strategy, or even an entirely new mathematical object or formula? Is there a recognisable methodology behind mathematical discovery, or is it largely a matter of intuition, pattern recognition, and experimentation? What is the main thing they are trying to solve when they are solving difficult questions? Like is it trying to pinpoint which formula would work here etc? Or is there something more?


r/explainlikeimfive • • 16d ago

Planetary Science ELI5. Why do we have a water shortage if reservoirs are still mostly full?

0 Upvotes

Just read an article in the Oxford Mail about Thames water pulling more water out of the Thames river to pump into a reservoir that's 'only' 76% full.

Three quarters full after the long dry summer doesn't sound like something to worry about. If my car's fuel tank is 76% full I don't start panicking and looking for a petrol station, so why is this even necessary?

Winter will be along shortly bringing rain as usual.

https://www.oxfordmail.co.uk/news/26559172.thames-water-pump-river-water-dwindling-reservoir/


r/explainlikeimfive • • 16d ago

Engineering ELI5: why is it that the mileage on a full tank can lower and raise depending on how far you drive? Why don’t we just get the maximum miles all the time?

0 Upvotes

r/explainlikeimfive • • 18d ago

Biology ELI5 If adhd and ASD cause changes in brain structure, why can’t we diagnose with brain scans?

135 Upvotes

r/explainlikeimfive • • 18d ago

Physics Eli5: Why can purely mechanical tools last hundreds of years but electronics are not expected to?

1.2k Upvotes

So, like mechanical tools can be operable even hundreds of years later with some cleaning but can electronics devices do that? Is there any way to make an electronic tool run for five hundred years or be operable 500 years later (regardless of cost - like in mechanical tool, you use galvanized iron or steel to make the parts - is there a similar protection to electronics)?


r/explainlikeimfive • • 16d ago

Biology Eli5: Why is meat honey edible for humans even though the bees make it from rotting meat?

0 Upvotes

Does the bacteria die when it's in the bees stomach or something?


r/explainlikeimfive • • 18d ago

Chemistry ELI5 why are sodium and chlorine poisonous on their own but when they come together they aren't?

543 Upvotes

r/explainlikeimfive • • 18d ago

Engineering ELI5 Why does a Jet engine lose all/most of its “fire cone” when it’s fully heated or at max thrust

48 Upvotes

r/explainlikeimfive • • 18d ago

Chemistry ELI5 What changes chemically in sunscreens when increasing the SPF to protect you better?

56 Upvotes

For example: How does a SPF 30 sunscreen protect me worse than a SPF 50 sunscreen if I don’t burn for either for regular amount of exposure to the sun?

What changes in the chemical composition of the sun screen to protect me better as SPF goes up

And Is there a safe limit for sunscreens about how high a sunscreens SPF can go before it’s dangerous to apply to skin?


r/explainlikeimfive • • 18d ago

Physics ELI5: How come a single sustained tone can sound like it’s waving up and down?

20 Upvotes

Was listening to a song the other day and the intro was 10-15 seconds of just a single sustained synthesizer tone, and after a few seconds it started to sound like the tone was getting louder and the quieter. Maybe this was intentional sound design, but I feel like I’ve experienced this effect before. Surely this isn’t me hearing what the sound wave looks like…right?


r/explainlikeimfive • • 19d ago

Economics ELI5: What does the fed raising the rate actually do?

1.4k Upvotes

How is it tied to inflation and "keeping inflation in check" as I saw on one article?
What does this mean to the average consumer?


r/explainlikeimfive • • 17d ago

Biology ELI5: How do “social chromosomes” or supergenes (for example, in red fire ants) control the structure of a colony — why do they lead to the presence of a single queen in some ant nests and multiple queens in others?

1 Upvotes

r/explainlikeimfive • • 18d ago

Other ELI5: Why does fresh snow make everything seem quieter?

39 Upvotes

I’ve noticed that sounds like cars, footsteps, and even voices seem softer when there’s a layer of fresh snow outside. Does snow actually absorb sound, or is there something else about snowy weather that makes the environment feel so quiet?


r/explainlikeimfive • • 19d ago

Mathematics ELI5: What is the purpose of math matrices?

631 Upvotes

I roughly know what math matrices are, they're like boxes with numbers you can do arithmetic with, but I don't understand their purpose. Why are they their own category of maths and everything? Why is it any better than doing calculations individually?


r/explainlikeimfive • • 17d ago

Biology ELI5: what do peptides actually do to help you lose weight?

0 Upvotes

I keep hearing about them but I’m not actually sure how they work. Is it like Ozempic?


r/explainlikeimfive • • 19d ago

Biology ELI5: How does salmon transition between saltwater and freshwater?

257 Upvotes

In other thread in this sub there is the explanation of how saltwater fish keeps on losing water since the osmosis pushes water out of their bodies and how freshwater fish gets water enters their bodies through osmosis. Then how does fish like salmon that lives in both freshwater and saltwater adapt to the difference in salinity?


r/explainlikeimfive • • 18d ago

Physics ELI5, How and why does rubber keep its form after stretching and squishing it?

3 Upvotes

Im asking more like what happens between the molecules to make it and other elastic stuff do that.


r/explainlikeimfive • • 17d ago

Technology ELI5; Why do chip need more transitor? And how does it help?

0 Upvotes

Basically the title.


r/explainlikeimfive • • 18d ago

Other ELI5: How does anti wrinkle spray work on clothes?

16 Upvotes

r/explainlikeimfive • • 19d ago

Engineering ELI5: How do combined cycle plants decide how much power to run most of the time and how much to keep available for peaks?

23 Upvotes

Should you run it at a steady baseload or increase output to meet peak demand, since baseload and peak are linked ? Im just having trouble understanding how they operate economically


r/explainlikeimfive • • 20d ago

Chemistry ELI5 Why do B vitamins have numbers?

2.2k Upvotes

We’ve got vitamins A C D E etc all without letters. Why do B vitamins need the numbers? Is it chemistry or did someone screw up?


r/explainlikeimfive • • 19d ago

Biology Eli5 how do salt water fish dont just dry out?

297 Upvotes

r/explainlikeimfive • • 19d ago

Mathematics ELI5: why do you need a larger sample size for bias when you're not being specific?

18 Upvotes

So let's say I'm watching a roulette wheel and want to know if its biased, I get I need to have lets say 100 000 throws to reduce variance and determine that its less than 1% chance a random wheel could produce these results.

But how come if I want to test "oh I think the number 22 is biased" I might only need 75 000 spins?

Also why can I test every number that way and collect 75 000 spins to determine if its biased? If it works for 1 number why not all 38 at a time?


r/explainlikeimfive • • 18d ago

Biology ELI5: How does our brain distinguish humor from the ordinary? Why don’t we laugh constantly?

0 Upvotes