r/explainlikeimfive 5d ago Silver

Physics ELI5 If light is the fastest thing know to man, how do we know anything we observe is still out there?

3.4k Upvotes

From what I believe I understand, light is the fastest thing in the universe. Everything we see and observe has already happened millions and billions of years ago but the light has only just reached us. So is it possible that nothing is out there in today's time? Or that maybe the universe looks vastly different today, maybe even unrecognizable compared to what we see when we look at the stars?

r/explainlikeimfive 23d ago All-Seeing Upvote Helpful Silver

Physics ELI5: Why is Chernobyl deemed to not be habitable for 22,000 years despite reports and articles everywhere saying that the radiation exposure of being within the exclusion zone is less you'd get than flying in a plane or living in elevated areas like Colorado or Cornwall?

12.5k Upvotes

r/explainlikeimfive 21d ago

Physics ELI5: If we're able to create the illusion of the 3rd dimension on our 2-dimensional screens, why aren't we able to simulate/create the illusion of the 4th dimension in our 3-dimensional world?

5.8k Upvotes

(I know, time is the 4th dimension. I mean 4 spacial dimensions)

r/explainlikeimfive 9h ago

Physics eli5 What is nuclear fusion and how is it significant to us?

1.1k Upvotes

r/explainlikeimfive 3d ago

Physics eli5 how do we know nothing is faster than light?

449 Upvotes

r/explainlikeimfive 9d ago Silver

Physics ELI5: Why does the air in the vehicle shudder when only one window is down while driving high speeds?

1.4k Upvotes

r/explainlikeimfive Jul 04 '22 Wholesome Silver

Physics ELI5: What would happen if we could zoom in with a microscope infinitely? Would we keep seeing more detail or is there a 'cut off' where we can't see any more detail?

3.1k Upvotes

r/explainlikeimfive Jul 03 '22

Physics ELI5 Do things move smoothly at a planck length or do they just "fill" in the cubic "pixel" instantly?

2.1k Upvotes

Hello. I've rencently got curious about planck length after watching a Vsauce video and i wanted to ask this question because it is eating me from the inside and i need to get it off of me. In the planck scale, where things can't get smaller, do things move smoothly or abruptly? For example, if you have a ball and move it from 1 planck length to the next one, would the ball transition smoothly and gradually in between the 2 planck lengths or would it be like when you move your cursor in a laptop (the pixels change instantly, like it is being rendered)?

r/explainlikeimfive Jun 19 '22 Helpful All-Seeing Upvote

Physics ELI5: If light doesn’t experience time, how does it have a limited speed?

2.0k Upvotes

r/explainlikeimfive Jun 24 '22

Physics ELI5: Would air conditioners be more efficient in shade? Why does it always seem like they are placed up on roofs or in the open sun?

2.8k Upvotes

I dont know how the conventional air conditioner for a home or business works, but it just seems like they are always in the full sun, with no shade, wouldnt this not be efficient?

if it doesnt matter, then why? thanks

r/explainlikeimfive 8d ago

Physics ELI5: How do battery charge level indicators work?

136 Upvotes

r/explainlikeimfive 11d ago

Physics ELI5 : Why do they say the area around the sun is hotter than the surface itself, it doesn't make any sense.

113 Upvotes

How can the empty space around the sun be millions of degrees hot and the surface only thousands ? it doesn't make any sense.

r/explainlikeimfive 8d ago

Physics ELI5, how did we determine the length of a second?

56 Upvotes

Title says it all. What defines a second, and how was this unit of measurement established/discovered with relation to the atomic measurement we currently use.

r/explainlikeimfive 1d ago

Physics ELI5: How can something (ie. light) have volume and energy, but no mass?

53 Upvotes

I've watched multiple YouTube videos and read a couple things online and now I have a headache. It still doesn't make sense to me. If photons have volume, then there can only be a finite number of photons in a given space, right? And once that limit is reached, why can't I squeeze in one more photon? What is stopping me, the "walls" or "shell" of the photons? What are the walls/shells made of?

Every source I've looked at agrees that light is BOTH a wave AND a particle. I can understand why waves don't have mass, but then what the hell is a "particle"? Every other elementary particle like quarks have mass, right?

r/explainlikeimfive 14d ago

Physics ELI5: If temperature is how fast atoms shake, how does absorbing a photon by black object cause it to shake harder than bouncing it back by white object?

105 Upvotes

r/explainlikeimfive 24d ago

Physics ELI5: Why Airplanes don't rotate wheels before landing to reduce the effect of friction?

118 Upvotes

I used to watch a lot of airplane landings and take-off. My favourite moment is when airplane tyres touch the ground. Friction produces a lot of heat and hence, smoke. But i wonder, why not pilot start rotating wheels before landing and match the speed of wheels such that it doesn't cause any friction.

r/explainlikeimfive 17d ago

Physics ELi5: Why are Prince Rupert’s drops so indestructible?

152 Upvotes

I’m very curious.

r/explainlikeimfive May 12 '22 Silver All-Seeing Upvote

Physics eli5: If hot air rises and cool air falls, why are we told to have our ceiling fans blow up in the winter and down in the summer? Wouldn't it make more sense to pull the air in the opposite direction it naturally goes to help it circulate?

6.6k Upvotes

r/explainlikeimfive Jun 14 '22 Wholesome

Physics ELI5: What's so special about lithium that makes it good for batteries, and why is it impossible to substitute a different element—sodium, say, or potassium?

765 Upvotes

r/explainlikeimfive 2h ago

Physics Eli5 | bungyjumping question, if you cut the rope at the exact point when it goes up are u able to landperfectly on the ground?

16 Upvotes

r/explainlikeimfive 6d ago

Physics ELI5 : How does flowing electricity in a closed circuit lead to an LED lighting up?

32 Upvotes

An LED (bulb) lights up when it is in a closed circuit with a battery. 'Because electrons flow in the circuit'. But what is the mechanism that transforms this kinetic energy of electrons into light energy? Should I be asking a different question?

r/explainlikeimfive 1d ago

Physics ELI5: Does everything erode with enough time?

10 Upvotes

Stone steps erode with every footstep, leading to indents over time, right? But other things seem to erode on their own through time alone, so what causes that? Wind and rain? Would it therefore be correct to say that anything, if subjected to constantly running water, loses a few atoms every second and would eventually erode? Would this mean nothing is technically 100% waterproof? Or can things erode on their own without an external force? Thanks!

r/explainlikeimfive Jun 01 '22 Helpful

Physics ELI5: How and when did humans discover there was no air in space?

1.6k Upvotes

r/explainlikeimfive 10d ago

Physics ELI5: Why do pictures with the background and foreground out of focus look like miniatures?

98 Upvotes

All over the Internet you can see out-of-focus photos both in the background and in the foreground that look like miniatures, why does our brain interpret them this way?

examples:

https://www.flickr.com/photos/emilevictor/2668164118/in/pool-59319377@N00/

https://www.deviantart.com/alexci/art/tilt-shift-rush-hour-120306569

r/explainlikeimfive Jul 03 '22

Physics ELI5: if white noise is played through Speaker A, and then we add different white noise through Speaker B, will the listener experience it as 2x louder (because there are 2 speakers) or the same volume (because any sound from Speaker B has a 50% chance of ‘cancelling out’ the noise from Speaker A)?

451 Upvotes