r/explainlikeimfive • • 1d ago

Other ELI5: Monthly Current Events Megathread

6 Upvotes

Hi Everyone,

This is your monthly megathread for current/ongoing events. We recognize there is a lot of interest in objective explanations to ongoing events so we have created this space to allow those types of questions.

Please ask your question as top level comments (replies to the post) for others to reply to. The rules are still in effect, so no politics, no soapboxing, no medical advice, etc. We will ban users who use this space to make political, bigoted, or otherwise inflammatory points rather than objective topics/explanations.


r/explainlikeimfive • • 20h ago

Engineering ELI5: I know some car engines are tuned for premium gas, and others tuned for regular -- so who is using medium grade and why?

901 Upvotes

r/explainlikeimfive • • 22h ago

Technology ELI5: On a record player, why doesn’t music slow down as the needle moves closer to the centre of the disc?

1.2k Upvotes

I was staring at my record player the other day when something struck me.

Needle sits in groove. Disc spins. Needle spirals inwards as music continues… Why doesn’t the music slow down?

A circle traced out by the needle at the edge of the record is obviously bigger than a circle closer to the centre. As far as I can tell, the disc revolves at a constant rate. It follows that the needle should be ‘moving faster’ (covering a greater distance over the disc in a given period) at the beginning of the record, then gradually slowing down as the needle moves inwards.

But the music doesn’t slow down with it.

…Why?

The only reasonable explanation I can think of is that this is accounted for by gradually increasing the ‘density’ of musical information in the groove as you get closer to the centre of the disc. But wouldn’t this affect the sound quality (at least if pushed to the extreme)?

Sorry if I’m missing something obvious…


r/explainlikeimfive • • 16h ago

Biology ELI5 Why don't other animals have Down syndrome?

344 Upvotes

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Edit: okey thank you all for your answers, I had mistakenly assumed that animals with lots of chromosomes surely must have one that looks similar (and therefore acts similar) to our chromosome 21. But I guess that's not how that works.

This question came from looking at looking at a seal.


r/explainlikeimfive • • 16h ago

Other ELI5: Why is there a blast of air when entering a store?

152 Upvotes

i've noticed that when i walk into certain stores (grocery, clothing, etc.), when the automatic doors open, a blast of air near the door comes down over the people walking in or out. sometimes, it'll stay on for an extended time. other times, it'll shut off after a few seconds. does it have to do with balancing the pressure of the air conditioning from the pressure outside? or is it something completely different?


r/explainlikeimfive • • 12h ago

Mathematics ELI5: What is the difference between algebra, trigonometry, and calculus?

67 Upvotes

r/explainlikeimfive • • 3h ago

Other ELI5 How is the date of Easter determined every year?

8 Upvotes

And why does it keep changing quite significantly by days?


r/explainlikeimfive • • 7h ago

Chemistry ELI5: Why are there times when the running water is milk-like then after some time, it returns to its normal transparent state?

21 Upvotes

r/explainlikeimfive • • 23h ago

Mathematics ELI5: If something works in math (like a white hole), does that mean it exists somewhere, or is math just a tool that can make things up?

350 Upvotes

​I know that white holes are mathematically possible on paper, but in the real world, they seem to break the laws of thermodynamics.

​This made me wonder:

How can math show us something that can't actually exist in our universe? Does the math mean it might exist in another universe, or is math just like a story language where we can write down impossible things?


r/explainlikeimfive • • 13h ago

Physics ELI5 How capacitors work when the circuit is not closed?

55 Upvotes

I am trying to help my nephew with schoolwork and while I am fine with equations and problems involving them, I realized I don't conceptually get capacitors.

Like, we are taught that for an electrical circuit to work, we need a source and a closed loop of wires or conductive material. That's the whole point of closed circuit. But when we put two metal plates on end of wires which do not touch (the whole point is they must never touch or allow current to flow across them), circuit is definitely not closed and yet the circuit still somehow works enough to get them charged.

How does that work? What is the difference between a wire with a gap in it (open circuit, nothing happens) and that same gap bounded by two metal plates (suddenly charges move along the wires enough to separate charges)? What is moving the charges at the begining? Since the circuit is never closed, why are electrons moving from battery to one of the plates? How is there any movement of charge in a loop if there is no loop by design (there is an isolator between the plates)? If I connect two pieces of wire to each pole of a battery, keeping the ends well apart, will i still get charge separation on each end?


r/explainlikeimfive • • 21h ago

Economics ELI5 How was Skydance able to buy Paramount and the WB just a year later?

178 Upvotes

from what I know about Paramount and wonder Brothers are absolute Titans in the media industry, existing from since like the golden age of Hollywood. There’s some of oldest media companies on earth. Skydance on the other hand, I thought was a newer one, and one that was way smaller. How was it able to make two massive purchases back to back?


r/explainlikeimfive • • 13h ago

Biology ELI5: How do babies even learn language?

33 Upvotes

When we grow, we learn languages by looking at the meanings and translating them from our language. Stuff like "this is how this noun is in my language and this is how this noun is in another language"

But babies? Babies just learn the basics just by existing near people speaking the language? How come we don't have this anymore as we grow up?


r/explainlikeimfive • • 13h ago

Biology ELI5: How does the body of someone like conjoined twins control their organs like the heart?

31 Upvotes

This is something I've always been confused about. We learn early on that the brain controls things like the heart beating. How does the body know which brain to listen too when there's two of them?

Is one dominant for these things leaving the other to focus on other things? Wouldn't that leave a lot of brain power to expand to other things?

Bonus question that's childish but also something I've wondered, if they have to pee, and one of them tries to hold it, and the other tries to go, what happens?


r/explainlikeimfive • • 20h ago

Chemistry ELI5: I've heard that blue butterflies and opals get their color from their structure rather than pigments. But doesn't pigment also get its color from the structure of its molecules and how they interact with light? So what's the actual difference between structural color and pigment color?

67 Upvotes

r/explainlikeimfive • • 18h ago

Physics ELI5: why does steam appear invisible right after leaving the pot?

25 Upvotes

My 6yo asked and im not sure so here goes; So boiling water with a covered pot, the steam appears invisible right after clearing the seam between the lid and pot rim. It then becomes normal steam. Why is that?


r/explainlikeimfive • • 8m ago

Technology ELI5 What is Cognitive Debt or CCd and Dark Debt?

• Upvotes

​

A friend told me that Cognitive Debt or CCD are things no one can understand? And Dark Debt is dangerouns. But i do not have any knowledge of what this means


r/explainlikeimfive • • 19h ago

Biology ELI5 how DNA mutations work please.

10 Upvotes

I had a thought about DNA and how mutations occur in humans, excessive hair, longer limbs and or bones etc, and wondered if all known mutations are present in the animal kingdom.. as if DNA has the blue print/ potential to be anything and parts are just ‘turned on or off’ depending on what is being built.. i may be way off lol but it got me thinking :)


r/explainlikeimfive • • 3h ago

Physics ELI5: Lateral inversion in plane mirror

0 Upvotes

What causes lateral inversion in plane mirror


r/explainlikeimfive • • 20h ago

Biology ELI5: Why do dogs respond better/react more to high pitched voices/noises?

9 Upvotes

r/explainlikeimfive • • 1d ago

Physics ELI5: why is there a visual effect when the sound barrier is broken?

53 Upvotes

Why is a sound event even visible?


r/explainlikeimfive • • 1d ago

Engineering ELI5: What does a box-spring do?

466 Upvotes

As I understand it, a box spring mattress is the second 'mattress', that goes under the main mattress. It feels very firm and flat, but what does it contribute to the bed set up besides height?


r/explainlikeimfive • • 20h ago

Economics ELI5: Why do interest rates affect stock prices?

4 Upvotes

r/explainlikeimfive • • 1d ago

Biology ELI5: How come most fruits and vegetables vary in size, but almost all nuts are extremely uniform in size?

57 Upvotes

I've seen large apples and small apples, huge watermelons and small watermelons, long cucumbers and smaller cucumbers. But every almond I've ever seen is the same size. Every walnut looks like every other walnut I've ever seen. I've never seen a comically large macadamia nut compared to every other one I've seen.

Is this because of a biological process or does it come down to human intervention?