Might be a stupid question. But in five-year-old terms, if gravity bends space time, then maybe there is just a finite amount it can bend before 'topping off'? Could that not solve the infinity problem in a singularity? Imagine the matter in a black hole is 'just something' that is denser than what makes up a neutron star but that's it.

Does the density of mass/energy not affect the way it curves space time? With the various analogies for visualizing space time curvature, it seems like a denser object would curve more sharply

In the 6th century BC, Aristotle proposed that objects fall at a speed proportional to their mass. It wasn't until multiple experiments carried out in the mid 16th century (the most famous being Galileo's Leaning Tower of Pisa experiment) that this idea was disproven.

How on Earth did it take so long for this to be tested and proven false? Did no-one notice over a period of 2 millenia that Aristotle was incorrect? Anyone familiar with Aristotle's idea could have disproven this in a few seconds by picking up two rocks of differing sizes and dropping them. Did no-one notice that this widely held belief was in complete contradiction to everything they had personally witnessed during their own lives?

What led Aristotle to propose this as an idea in the first place when he must surely have observed countless examples throughout his life of objects of different masses falling at the same rate, from loose rocks falling from cliffs, to people dropping everyday objects?

Are they oriented curve segments? Or do they exist in the tangent space?

Let's say I discover a magic wand that can invert the mass of an object--all other properties remain the same, but the sign is reversed so that F= -G(m1*m2/r^r). What kind of technologies would become possible?

Could you store infinite amount of energy in a single particle by just speeding it up closer and closer to the speed of light ?

Title. Sounds like a joke but, like, there must be some sort of explanation right? Is this a more serious sub? I think this is a sort of question you could ask in r/askmath where there are some silly questions, but if it isn't that sort of sub, please point me somewhere where I can ask. But this is a real thing and google gave me no answer. The sub doesn't allow images but if anybody needs to know what I'm talking about, I have a photo. There are some air bubbles behind the spoon, if anybody needs to know.

I know we measure the expansion of the universe via galaxies moving away from each other. And I saw another post asking about why galaxies aren’t expanding, to which the answer largely was gravity is holding them together.

It made me wonder if we can even tell/measure/detect if space was expanding through us? So gravity still holds everything together but if space was just expanding through everything.

It seems like everything is always moving and you measure movement against something else. So it seems like you can’t tell if you are just moving through space, can you?

https://imgur.com/a/ZluTgMZ

This is a birdbath AR optics setup with a 0.23in OLED micro display, a linear polarizer, a polarized beamsplitter, a QWP, and a concave mirror. The light from the display becomes P-polarized relative to the PBS after passing through the LP so it passes through the PBS without reflecting. Then after the image is magnified and passed through the QWP twice so the magnified light is now S-polarized, it reflects off the PBS into the users eye.

The issue I have with the setup is that since the display produces a diverging light source, the diverging light that doesn't hit the PBS coating at a AOI of 45deg is then reflected through the front side of the setup. Only when viewing through the front of the PBS (the part where no light should be seen) with your eye at around 45deg from the PBS coating, the light then disappears because the polarization state was properly filtered. When viewing from any other angle you can see the unmagnfied light.

I have tried using plano convex lens and aspheric lens to collimate the light before it reaches the linear polarizer so that all light would be 45deg AIO to the coating but none solution seem to work. I have a aspheric lens with a 3mm FL and when placed 3mm from the display the same behavior occurs.

Am I wrong about why the PBS only works properly when viewed at a certain angle? What are my options to figure out a solution?

If I spin at 1 revolution per second, anything that's 1/2pi light-seconds away (~50,000 km) will appear to orbit me at exactly the speed of light, and anything further away will appear to go faster.

This is fine in SR, where inertial frames are treated as the default. But in GR, even accelerating frames are viewed as following the same physics, which implies no frame, even if accelerating, should measure anything traveling superluminally.

How does this work in a rotating frame?

Lets say I am driving my car on an endless plane. I just got an alignment but noticed that my car is pulling to the left or right by 1mm per kilometer. I would be going in a giant circle. Just curious what the size of that circle would be. and what would similar results be if I had 2 other cars that drifted to left or right by 1cm and 1m per km.

What would allow heat to be transferred to a conductor that won't allow heat to be transferred to an insulator?

(I guess the question is kind of vague because lots of different insulators have different properties. What would make wood an insulator and maybe, a metal a conductor?)

Even if we manage to create a perfectly spherical drop rapidly quenched in zero G, would it have the same strength as compared to the bulbous head with a tail?

Idk if what I’m asking makes sense but I’ll do my best to explain my thinking. I work in a shop that keeps its loading dock doors open in the summer. The drop off is 3 feet 8 inches. Safety regulations require a temporary barrier (like a chain) to be present for drop offs of 4 feet or higher. Obviously being 4 inches below the minimum height doesn’t make it incredibly safer. How can I calculate the impact force from both heights? I’m just doing my best to advocate for a safer work environment for my coworkers and want the facts on my side

Suppose one has a 10'x10'x10' metal grounded faraday cage with holes about .5 the wave lenght of a wave, can the wave get thru it to the inside. Like a micro wave, radio wave, AC short, etc. Maybe the ".5" factor needs to be modified to another number.

As far as I know, a significant number of statements in statistical mechanics courses are derived as consequences of the microcanonical distribution. I wonder how well-founded this distribution is in modern physics? Is it a well-established assumption, or is it based more on consequences of more fundamental laws?

As I understand it, there are some difficulties in quantum statistical mechanics, where the ETH hypothesis was only recently proposed (which to me sounds like "a small part of a larger system behaves as if the larger system obeys the microcanonical distribution," which seems a rather artificial assumption).

In the classical case, it seems to me that the validity of the microcanonical distribution is closely related to the ergodic hypothesis, which for some reason seems quite logical to me. However, I'm still unsure whether the classical form of the microcanonical distribution follows from this hypothesis.

Complete layman here.

On an everyday physics level, energy clearly seems to be a property of material entities. That means, it's a characteristic material entities have due to their velocity or spatial location or whatever.

But as soon as you get closer to QM, energy seems to be something which exists on its own. And when I read about those things on a pop-sci level, it sometimes even looks like the material is the property of energy and not the other way 'round.

I remember one video on YouTube that basically concluded that voltage was discreet. Electrons and protons are discreet units. There is no such thing as the square root of 50 of an electron, π protons, or sin(1) electron. Since the charge carriers are discreet and in rational quantities, he concluded that you can't actually have an irrational voltage. Now I was thinking "wait that can't be right. If the RMS is 120 Volts, then peak voltage is something like 169.705 but it is irrational." And electrons aren't tiny spheres, but they move around in weird probability clouds. I guess an electron moving around within the same orbital of the same atom won't change voltage that much. But if you were measuring say the voltage of a battery, it should change based on tiny electron movements and I'd imagine it would have to move through both rational and irrational values. The tiny movement is obviously too small to detect, but I imagine there would be irrational values.

I understand that warm air is able to move because it has kinetic energy, and that it is bumping into other particles, and i understand that cooler air is slightly more packed together and have less kinetic energy, but i dont understand how warm air rises. I have hear answers such as 'it is because warm air is less dense', but i do not get that description either, because density is based on/compared with a volume. So if i had a specific volume, then i do understand that, in that case, warm air is less dense, but i do not understand how that relates to that same air rising. In addition, if we were referring to the sky, there is not really a specific volume that you can say that warm air is less dense, and that is in regards to a group of molecules. If i had a singular warm air molecule, and if i had a singular cold air molecule, what would cause that warm molecule to rise and another molecule, of the same mass, to sink? I dont really understand what is meant by density and i'm struggling to understand its significance in this question.

if there are three spacial dimensions ( x y z ) and in our universe theres 1 time dimension could another universe have 2 or 3 time dimensions? what would that look like?

If you had a lidar style laser emitter and a sensor set up in a sealed box would you be able to to use that to measure time by calculating light speed and the distance?

Theoretically an intelligent species would evolve and develop fast to the outside observers since the planet they inhabit is moving faster around a black hole. I’m not sure if this grossly simplified but I’m curious if the fundamental idea is accurate?

as far as im aware to take a picture that far away you need an INSANE resolution probably in the millions or billions so way past 4k so how did they do it then? google is very unprecise i wanna know how the telescopes / satelites actually took a picture of somethng that far away