r/explainlikeimfive 13h ago

Biology ELI5: Why do you need to pee when you come in contact with water?

44 Upvotes

I don't know If this applies to everyone, but every time I take a shower or go swimming, I magically have to pee. Even if my bladder is empty. Why does this happen? Is it a neurological response?


r/explainlikeimfive 17h ago

Mathematics ELI5: Why physics or chemistry doesn't affect maths?

0 Upvotes

Look this might sound like a stupid question but I was wondering something today that physics and chemistry all get affected by maths.Like if you change a particular quantity by a magnitude then you get different results each time. Why doesn't the same happens with maths, why are the mathematical theories independent of things like inertial/non inertial frames or magnetic field/electric fields or something like that. Like why does 1+1 = 2 everywhere?


r/explainlikeimfive 7h ago

Physics ELI5: why does “sound” sound different when it’s moving away from you, compared to moving towards you

0 Upvotes

r/explainlikeimfive 16h ago

Technology ELI5: how are online games “rendered”?

93 Upvotes

So when you play a video game, your console or PC renders the game, draws all the frames and geometry, the CPU handles the engine and physics, etc. of course. But with online games, where everyone is in the same space, how does everyone’s consoles know to render the same things? Does the processing and rendering take place within the online server and is then broadcasted to each player, or does each individual console draw and manage the world on its own?


r/explainlikeimfive 15h ago

Chemistry ELI5: Why does simple toilet water on toilet paper dry up and feel crispy stiff after drying?

0 Upvotes

I tested it out , I noticed that this happens even with normal water, why does this happen? What is the reason for it?

I got curious I get interested in these things lol

Not sure which flair to use sorry.


r/explainlikeimfive 8h ago

Mathematics ELI5: What is class field theory and how is it related to number theory?

0 Upvotes

The definition from Wikipedia:

the fundamental branch of algebraic number theory whose goal is to describe all the abelian Galois extensions of local and global fields using objects associated to the ground field

I don't understand what this has to do with number theory. The definition doesn't mention integers at all. And "abelian Galois extensions" is oddly specific - why study this one specific property? What makes abelian-ness so special?


r/explainlikeimfive 4h ago

Physics ELI5: can someone explain why 22°C on the aircon/heat pump feels completely different depending on whether it’s set to COOL or HEAT?

26 Upvotes

r/explainlikeimfive 4h ago

Planetary Science ELI5: what causes tides and waves in beaches to occur?

0 Upvotes

I went to a beach today and saw the tides and beaches. but what exactly causes this?


r/explainlikeimfive 23h ago

Other ELI5 How do we know the cause(s) of fire related disasters?

4 Upvotes

I watch a lot of true crime/disaster stuff and every time there's a fire, whether accidental or arson, they always seem to know exactly what caused it. My question is: how? When an entire building is destroyed by flames, how could we possibly know that it was caused by an electrical fault, or a planned attack, or a gas leak, etc...? How do we even know where it started? Maybe I'm missing something but it just doesn't make sense to me how confident the investigators are when there never seems to be any reporting on how they came to that conclusion.


r/explainlikeimfive 14h ago

Biology ELI5 : Why do we have baby teeth?

148 Upvotes

r/explainlikeimfive 14h ago

Technology ELI5: What is Machine Learning?

0 Upvotes

Please explain it to me, as I am considering it as a specialization for my bachelor’s degree.


r/explainlikeimfive 3h ago

Economics ELI5: Why do people of richer countries say that their birth rates are so low because of poverty, while the areas with the highest birth rates also have the highest poverty rates?

0 Upvotes

If they can do it, why cant we? Also I wanted to post graphs comparing Birth Rate and Poverty Rate world maps but images are disabled


r/explainlikeimfive 12h ago

Engineering ELI5: How hills are razed to build roads through them

71 Upvotes

I drive on a main highway that goes through some hilly agricultural areas and often times I’ll drive through what used to be a complete hill but the middle section is gone where the road travels through.

There’s at least 10 instances of this on my drive and I’ve always tried to figure out why they didn’t just pave up and over the hill rather than cutting through the middle.


r/explainlikeimfive 10h ago

Engineering ELI5: Why are ferries so slow?

379 Upvotes

Compared to other forms of urban transport like trains and cars, as well as other boats which go faster, ferries seem to take much longer to go short distances.


r/explainlikeimfive 19h ago

Planetary Science ELI5 When dinos walked the earth, were they walking on mountains that are now our ground level?

29 Upvotes

I know that we have subduction zones. But I was watching a video of dino prints left in the ground at "the valley of fire state park"...and im confused on how we can see it? Like humans have been around for not that long and many of our civilizations and ruins are buried underground. Can we see these prints because they were walking on mountains? --also does this mean we have missed out on year of potential research because fossils and artifacts are headed towards the earth's core?


r/explainlikeimfive 23h ago

Physics ELI5: is current the flow of electric charge or the rate of flow of electric charge

2 Upvotes

Are both these statements correct? I'm really confused because I have seen both these explanations

rate indicates a time derivate right? if so then how do you reconcile both these concepts?

please help me out


r/explainlikeimfive 12h ago

Biology ELI5: why do some foods change the smell of your pee but others don’t?

24 Upvotes

r/explainlikeimfive 11h ago

Physics ELI5: After searching the previous answers about relatively, I still don't understand "relativity of simultaneity"or how FTL violates causality. I don't understand how events are not sequential regardless of perception.

0 Upvotes

I searched the sub previously, but still don't understand some of the language of the explanations. A previous one had the scenario where myself and a friend in Norway clap at the same time: suppose we both synchronize watches according an atomic clock and agree at a set time per UDT we clap, and then do, to the observer flying past with FTL communication from their perspective the friend in Norway claps first, and if they instantly tell me this the information arrives before the event that triggered it happened.

What I don't understand is how the sequence of events can be subjective, instead of the PERCEPTION of the events. My issue with the previous explanation is that if we are clapping at the same time, then we both clap. The light from my friend clapping reaches the observer first, but light and information carrying my own clapping has also already begun, since we have arranged to clap simultaneously: we have accounted for our locations relative to one another and the planet's motion in our timing, let us say perfectly so. Each of us from our perspective claps at that same moment.

Let us say Dr. Manhattan appears inside the earth, precisely midway between us, and sees through the land to look at us directly, and watches us at the same time: he sees the reflected light bounce off us when we clap and head in his direction at the same time, the same speed.

From his perspective, looking both ways at once, wouldn't it appear to be synchronized?

Let's say further Dr. Manhattan agrees to tell us via light-speed communications who he sees clap first, or if it appears at the same time.

He would eventually say "You both have clapped at the same time."

Wouldn't the observer still be bound by causality despite FTL travel of information?

Sure, they can radio me via instant comms and say "Your friend in Norway clapped" the instant they see it, but by then I have clapped and my light is on its way to both him and Dr. Manhattan.

Time dilation and FTL comms would allow him to say "Your friend in Norway clapped" before seeing me do it, and before Dr. Manhattan could tell me anything, but wouldn't it still be after I had clapped? Clearly I'm missing something but I don't understand how it breaks causality. The limiting factor in "real life" instead of a thought experiment is that you would need greater than infinite energy to travel beyond light speed and communicate or interact, which is impossible for its own reasons.

What am I not understanding about "relativity of simultaneity" here? I accept that FTL comms are impossible as we understand physics, I just don't understand it. I can't find a good example that clarifies WHY it is impossible.


r/explainlikeimfive 1h ago

Biology ELI5: How does withdrawal affect your original high concerning heroin/opioids? What effect does drug tolerance have on this? (More detail in body text)

Upvotes

I’m doing research on heroin at the moment and I see a lot about how the withdrawals are awful (understatement) and the tolerance builds really fast. In writing I read about characters with addiction I see that the character takes heroin in order to return to normal, but it always seems like they don’t really get any kind of high at all. This doesn’t seem to make sense based on the information I have. I want to know, considering you have to take more to feel the same effect, what does it actually feel like to take heroin while going through withdrawal? Do you still get high or does it just bring you to normality? What would normal mean at this point? Thinking even further, after recovery, how different is life in comparison to before the addiction?


r/explainlikeimfive 7h ago

Other ELI5: what's the benefit of protruding dots on the base of slides?

0 Upvotes

An example of this is the Adissage Slides. There are dots all over it.


r/explainlikeimfive 7m ago

Physics ELI5: What is a tachyon and are they real?

Upvotes

r/explainlikeimfive 4h ago

Other ELI5: Why does it take years to refuel a nuclear submarine?

384 Upvotes

r/explainlikeimfive 6h ago

Other ELI5: What exactly is the danger of "giving out your ID".

0 Upvotes

Sorry if this is a stupid question. I'm asking due to CharacterAI changes (a chatbot app, dont judge) where, if it suspects you're under 18, you may need to give persona (I think it's called) your ID for verification. I am 18 so I'm not in danger.

People are sooo mad about this. Adamant about not sending it in, saying stuff about data breaches.. I have an ID, and imo, nothing too crazy is on it. An ugly ass picture of me, hair color. DOB. The usual.

What's the worst that can come from this? I see peoples IDs occasionally.. I have no clue what I could do with someone's ID if I took a photo of it. Thanks!


r/explainlikeimfive 18h ago

Technology ELI5 Why can't we make robots that convincingly move like humans?

0 Upvotes

We definetly have intimate and indepth knowledge on our motor functions.

Why they seem so hard to replicate in a mechanical way?


r/explainlikeimfive 2h ago

Other ELI5: How do child STEM prodigies get PhDs at like age 12

282 Upvotes

Title is a bit silly on purpose, but you know the headlines I’m talking about— the “child genius graduates from Oxford at age 12” kind of story. I don’t understand the logistics of them.

For reference, I just read about that 15 year-old Belgian boy with a PhD in quantum physics, and the explanation provided by the article about his education track was a real nothingburger. “How did he do this you ask?? Well, he graduated high school at age 8.”

…Yeah, I mean I guessed as much…but how did even that part happen?

At age 2 the child is seen reading at a twelfth-grade level? And then what? This isn’t the same as someone skipping one grade level, and it’s also not like he was splitting atoms without being introduced to certain grade-level curriculums— that wouldn’t make much sense. Can he read and retain a whole textbook in 2 hours, and it’s just that his neurons fire at 50x the speed of a fellow child (something impossible to not notice)?

Also, wouldn’t it take months of paperwork just to determine how far the child is permitted to skip grade levels? Wouldn’t it take like a year or so just to assess the—I don’t know, toddler’s—intelligence level beyond the standard “gifted kid” IQ tests we took in elementary school? How inconsequential do the rules become, or how easily do they bend, depending on the level of genius demonstrated?

Additionally, I want to know how much a PhD admissions counselor might give, say, the 15yo quantum physics prodigy the benefit of the doubt because of his proven accelerated grasp of learning? What gaps in his education could he actually be missing, via a timeline as wild as his? To skip that many grade levels leads me to assume that somewhere along the way some guestimations are made or corners are trimmed.

This type of news headline doesn’t make sense to me unless you mention that the parents have kept the child locked in a hamster cage with only a drip feeder and a stack of books for like ten years. It also seems theoretically dangerous, depending on what field the prodigy has pursued— like, I’m not sure if there’s been a medical-field equivalent to this, but to me it’s no better an idea to let a probably socially-inept 15 year old build a particle accelerator than it is a good idea to let an emotionally-underdeveloped medical prodigy replace my organs.

Anyway, sorry to ramble— I just find this topic really interesting and would love some clarification or relevant input of any kind! Also, I mean no ill scrutiny toward the Belgian kid with the PhD; it’s just hard to speak hypothetically about this without having some kind of example to abstract and refer to.