ELI5 spf 41 vs spf 40???

i notice some skincare brands use spf 41 instead of spf 40...can anyone explain the difference? 41 seems like an odd choice...

https://redd.it/1rywtfh
@r_explainmelikeimfive

ELI5: At what point does the body start eating muscle during a calorie deficit?

I’ve been reading quite a lot about weight loss and I’m getting mixed statements about retaining muscle mass during a calorie deficit. If somebody is very obese, let’s say 35% body fat, and they reduce their calorie deficit to lose weight, will their body start eating muscle as well, or do you have to be already below a certain body fat percentage before your body starts cannibalizing its own muscle during weight loss? I know heavy lifting helps preserve muscle mass during weight loss, but at what point does it become necessary is my question?

https://redd.it/1ryyw9h
@r_explainmelikeimfive

ELI5: What is the science behind someone being irritable when they are hungry?

When I am hungry, and someone tries to talk to me (especially when it’s something I couldn’t care less about), I would be like “dude, go away, I don’t care”. I feel a lot less snappy when my stomach is filled. Apparently, this is the same for a lot of people. But I still have no idea how my stomach and emotions are connected.

https://redd.it/1rz0ubk
@r_explainmelikeimfive

ELI5: How does our Earth, the Moon, and every “big rock” that spins… spins?

So far I’ve learned that Earth and Moon for example, spins at their own “center-line” while traveling around a given “path”. What is the magic/energy that makes these happen?

https://redd.it/1rz1ea1
@r_explainmelikeimfive

ELI5: Does hitting a baseball thrown by a pitcher give it more or less energy than if it was hit off a tee with the same force?

I would think a pitched ball would have less energy when hit, because the force of the bat has to overcome the kinetic energy of the ball moving in the opposite direction.

But having played kickball, it always felt like I could kick the ball farther if it was rolled fast at me vs. kicking it from stationary. Could it have something to do with how bouncy the ball is?

https://redd.it/1rz3637
@r_explainmelikeimfive

ELI5: How is a petri dish of neurons able to play Doom?

Just read this article:

https://www.theguardian.com/games/2026/mar/16/petri-dish-brain-cells-playing-doom-cortical-labs

And I know it says "electricity is the common language between neurons and the computer system," but, how are they understanding, learning, and responding? I'm not fully getting it. Thank you

https://redd.it/1ryxcu9
@r_explainmelikeimfive

ELI5 How do MRIs and CT Scan machines work?

I recently had an accident (not at all serious) for which I was precautionarily given mri & ct scan appointments.

While I was undergoing those I couldn't help wondering how these machines work.

Must be an absolute marvel of human ingenuity and precision engineering.

https://redd.it/1rz390u
@r_explainmelikeimfive

ELI5 what is .NET runtime for, and what does it do?

I see it installed as a dependency for all kinds of games but can't really find an answer online that makes sense to me as to what it is. I'm majoring in computer engineering (RIP) so I feel like I should know what it is

https://redd.it/1rzbww0
@r_explainmelikeimfive

Eli5 how were log cabins/wooden buildings protected from rot, historically?

Why didn't logs decay, or did they, and how were they replaced? Give me the play by play through history, when people lived in wooden buildings what kept them from rot and decay?

Idk what flair was most appropriate.

https://redd.it/1rzgxeo
@r_explainmelikeimfive

ELI5: How did scientists confirm/know that it rained continuously for millions of years during the carnian pluvial episode?



https://redd.it/1rzh4do
@r_explainmelikeimfive

ELI5 how appraisers and collectors tell if an autograph is fake?

I was looking through memorabilia to buy for my son’s birthday. He’s a big fan of a few hockey players on his favorite team. It got me wondering:

If someone took the time to perfect someone’s autograph to where it was identical to the real one, how can appraisers and collectors tell if it’s a fake?

https://redd.it/1rzfd5z
@r_explainmelikeimfive

ELI5 How can I tell what Phillips size bit goes with which Phillips head screw?



https://redd.it/1rziozb
@r_explainmelikeimfive

ELI5:How do electric eels make electricity?

I only know that they aren't really eels but some other species of fish. I have watched some videos but it's too complicated for my small brain

https://redd.it/1rzkink
@r_explainmelikeimfive

ELI5: How does scratching to ease an itch make any sense

It is just intentionally produce pain to distract another issue, does all animals do the same? Is it a psychological vs physical trade off situation? Genuinely curious.

https://redd.it/1rzg126
@r_explainmelikeimfive

ELI5: When recycling glass, why is it crushed and melted? Wouldn't it be easier to just sanitize and reuse the glass?

Would that not be more efficient?! How does this process work?

https://redd.it/1rzogpm
@r_explainmelikeimfive

Eli5 what does palantir technologies actually do

As far as I understand they're evil and make spying technologies, But like what stuff do the actually make? What do they do?

https://redd.it/1rzpxpx
@r_explainmelikeimfive

ELI5: How does twisted pair work at reducing interference?

How do twisted pair cables work at reducing interference? And how does it affect internet speed? Also, why are cables working with frequencies? I was always thinking of cable transmission as simple bits running from point A to point B.

https://redd.it/1rzldsl
@r_explainmelikeimfive

ELI5: Why doesnt the gulf states send their oil through the red sea instead of shipping throught the straight of hormuz?



https://redd.it/1rzsp70
@r_explainmelikeimfive

ELI5: Why are airplane bathroom trash receptacles designed to involve so much skin contact?

There has to be a logical explanation for this, but I’m seeing nothing online…

Question is simple. The vast, vast majority of airplane bathrooms, regardless of age of plane, use a spring-loaded trash can lid that will snap closed, usually clamping whatever it is that you’re trying to throw into it. I’ll usually walk into a plane bathroom and see that thing munching on whatever the last person attempted to throw into it.

A tiny number of planes have a pedal system, but still to operate a spring-loaded lid. Now, on the ground, I feel like we’ve designed a bunch of functional trash cans. Whether that is a sensor-operated lid, a slower release system on the spring so that it takes longer to snap closed, a pedal, or even just no lid at all, I feel like we have a million ways we are able to dispose of trash more conveniently.

Are there regulations or engineering constraints that make airplane trash cans work the way that they do?

https://redd.it/1rzv19u
@r_explainmelikeimfive

eli5: why do hangovers get worse as i get older



https://redd.it/1rzza4a
@r_explainmelikeimfive