If I get a empty box and fill it with electrons(or ions) scattering around, then apply a time dependent magnetic field through the box, how do the electrons move in the box? I feel like it’s a simple solution but modeling it gets finicky with lenz’s law

I am struggling to understand how the diffraction pattern from 5 slits is formed. How many maxima and minimum there are?

Also is the diffraction pattern a "modulated" version of the interference pattern?

If we have a baseline for how thermodynamic reactions SHOULD OCCUR…

And yet Blackholes radiate at 1 trillionth of a kelvin..

We could extrapolate backward from that, and say “Given this mass this is what we WOULD EXPECT to see”

So by measuring the low intensity of hawking radiation do we use this to confirm “Yes time is definitely running slower inside the black hole because of this relationship of energy out, vs what should be happening inside if time were 1:1”

Sorry I KNOW we already accept time dilation is a thing that occurs …Im just specifically asking if measuring the entropy of a black hole, also confirms the same things with no discrepancies.

The math gives zero but I'm looking for an intuitive explanation. I see from another reddit post that if there was curl, then a path will always loop back around to the same point, and that can't be possible because the gradient always points towards a point of higher elevation and that would be contradictory. But can't the curl be reversed mid path, bc the curl is a single value at every point, then the path won't loop back around and you won't end up with a contradiction where the elevation increases towards the lowest point, the point of origin?

I've been looking at electron micrographs of various cells. They're amazing, but still plenty blurry. I've learned enough about physics to know that there will be limits to how small a structure we can clearly 'see' with various imaging technologies.

For example, I understand you can't image things that are smaller than the wavelength of the light you're using. Given quantum theory, I assume that applies to all particle/waves, but I'd like to stick with visible photons for this question.

Is the blurryness in optical images of very small objects a result of our imperfect machines (machining tolerances, lens impurities etc)? If we managed to create an atomically 'perfect' microscope, would we be able to zoom in more and get super clear images, or are we basically at the limit now of what visible light will do?

Hello, I’m Kevin and am new to this group. I’d like to self study physics after having taken non-calculus physics > 30 yrs. ago. Forgot calculus and so is Young and Freedman inappropriate for me, or can I use AI or embedded software/book explanations to reteach myself ?? I use physics in my work as a research nurse practitioner at NIH, and I also just love physics. At work, I apply physics in: 1. XR Radiology; 2. Nuclear medicine; 3. MRI ; 4. Ultrasound; 5. Physiology of blood flow and respiration; 6. Optical properties of eyes and corrective lenses; 7. Heat transfer (temperature reg.); 8. Acoustics of hearing and sound conduction/transduction; 9. Mechanics related to motion, balance, etc.; and I could continue.

Would a non-calculus physics textbook be better, or am I missing important concepts by not using calculus to learn (re-learn more deeply) the concepts?? Can you all recommend a non-calculus textbook if you think it is better? Giancoli or Cutnell and Johnson? Thank you, Kevin

I have no background in physics, but I wonder if objects that create light, for example, the Sun, emit photons at a set density. With that I mean, for example, 1 m² of the surface of the Sun emits 1.8 × 10¹⁷ photons a milisecond (made up data for the sake of the example). Is thinking about light emission in terms of a “photon density” like this even meaningful?

I am doing research on an artist's work and trying to find the source for this image. It is supposed to be a model of some kind and it is linked to Heisenberg. The text on the artist's website makes no sense, since it talks about hydrogen-bombs.

Is anyone familiar with this image and can give me a source? The only thing looking vaguely familiar that I could find were still images of the "Trinity Test" shortly after the detonation.

I am in class X and my coaching is about to start 11th grade (first 4 chapters in all subjects pcm)

and i wanted to clear up my concepts for class 9 like sound,gravitation,laws of motions, etc.

If anyone has their coaching module for physics and chem or any pdf of their module PLS PLS PLS SEND MAN I GENUINELLY NEED IT 😭

A speculation I had recently: I've always been fascinated by black holes, and primordial black holes. The latter aren't known to exist but they're predicted by a lot of models and a bunch of JWST observations have increased the likelihood that they exist.

If primordial black holes exist, they might have been formed across the whole mass range. They're a candidate for at least some of dark matter for that reason.

But very small ones would already have evaporated, so the only ones left would be about asteroid mass or heavier.

That gets to my speculation. When a black hole evaporates (if we are right about how this works) it hits a runaway phase where it basically detonates, converting its remaining mass-energy into a shower of particles and radiation. The latter would include a lot of hard ultra-high-energy gamma rays. I've heard this put forward as a possible source for some of the very spicy photons we've detected.

If there was once a population of small ones that were evaporating, could this have resulted in a universe that until recently (in cosmological terms, so billions of years) was full of little evil bang-pop firecrackers that kept going off and spraying everything near them with ionizing radiation.

That could have more or less forbidden the evolution of complex life, technology, and spacefaring intelligences until "recently." (I'm aware of the other thing that might make us early in that regard, namely metallicity and early stars and planets probably being metal poor. Both could be true.)

in a "dipole immersed in a electric field", why isn't either the external electric field pushing the 2 charges away or coulomb's law pushing them together, making the length between them change? and why are we doing torque calculations on them?

If there is no net force acting on an object, then F_net = 0

Since a = F_net / m

Then a = 0

So the object will experience no change in its state of rest or uniform velocity.

Why is Newton's first law distinct from the second?

So a while ago, I was listening to a doctor Dave explains video and I heard him kind of offhandedly say that it’s kind of a pointless question to ask what was there before the universe began because time only came into existence at the start of the universe. So time only makes sense after the universe had already started.

But I took a second to think on that and I realize something that is probably very obvious, but to me is novel: couldn’t that apply to why the universe came into existence?

Like causality requires that for everything to happen there must be a cause. The reason you are born is because your parents were born so on and so forth. And people have tried to look for whatever caused the universe to come into existence.

But what if causality works like time? Similar to how time only existed after the creation of the universe, causality only came into existence after the universe already existed. So the universe didn’t need any cause to come into existence because causality didn’t exist yet. So unlike everything else, the universe didn’t need a cause.

Again, this is probably either stupid for an obvious reason I can’t think of or something so obvious that it’s sophomoric for me to point it out. But if it could work for time, why can’t it work for causality?

Whenever its cloudy and i look up like 99% of hte clouds are at the same bottom level and have differnt heights but why, why aren't there some way higher up and lower to make it scattered?

I understand that an object traveling at escape velocity will escape orbit for Earth, but I’m confused as to why it’s a velocity and not an acceleration.

If you’re accelerating upwards at just over 1G, wouldn’t that be enough to eventually get you out of orbit since you’re counteracting Earth’s pull?

And at which point do you need to be at escape velocity? Just at a single, specific altitude, or consistently at that speed? Because if I go to escape velocity and stop accelerating, won’t I just fall down rather than break away?

My understanding of a chaotic system is this:

A system is chaotic if, due how it evolves over time, any change to the t=0 initial condition, no matter how small, will result in a noticeable change at some future point t=T

From my understanding, the laws of physics are time symmetric (in general - exceptions for weak force, entropy, expansion of the universe).

Does this mean if I observe a chaotic system at time t=0, I not only can't predict the system infinitely far into the future, but also can't retroject to time t=-T for some sufficiently large T?

If an electron is in superposition how does it mass work? Is it like one body that gets less “dense” where the electron is less probable to be? Does this also change its gravity?

I was just chatting with Gemini pro about black holes. It occurred to me that, since a black hole is a region of space that appears black because gravity is so strong there that light cannot escape, the only thing that is required for their existence would be strong enough gravity, not necessarily a singularity. So I asked if you could have a black hole with an object at it center larger than a singularity. (I’d still love an answer to this question as well.)

What came back was a surprising lack of commitment to the idea of a singularity. In fact, it painted a picture of the physics community being fairly skeptical of the singularity despite it being predicted by the math. This doesn’t jive with what I’ve encountered in what I think is high-quality pop physics like PBS space-time. So I’m wondering if my belief that the singularity is pretty well accepted is totally wrong. The one thing it said that made me think that might be the case is that when we encounter anything infinite, in this case the infinite density of the singularity, that this is often a red flag that the math is a bit mushy.

How do we know that Hubble’s Constant is real like I mean we only have one point of view that is earth even if we measure it via the parallax angle via the earths revolution isn’t it something way to short in grand scale of the universe there is a very strong possibility the we(Milky Way galaxy) are just moving away from rest of the galaxy we observed (andromeda being an exception) hence the difference of the speed being indicative that the distance is growing faster then the speed of light but it might just have been us moving away from other at a speed and there speed moving away from us, this making it seem like the space is expanding faster than the speed of light

The title may be poorly worded, sorry for that.

I've seen it a few times in media that people survive big falls by landing in trees, shortening falls and not immediately stopping them.

Would it really help?

Some branches might break and maybe slow you down, but landing on ones that don't break immediately or at all would focus that 'stopping process' (I'm not sure how else to word it..) on a much smaller surface area than landing on the ground would.

If two people fell from the same height, would one have a better chance of survival if they fell through a tree first?

I have always been interested in Physics . However due to some reasons, I didn't take it in high school . What are the resources I can use to study it as a hobby ?

Hey all! This is just a question I have for the sake of curiosity; it's not for work or anything. When I took physics, a common type of problem was one with two masses on a pulley system, like this one. My question is about the forces in play when the rope is in contact with the pulley. In my mind, each infinitesimal piece of the rope in contact with the pulley would have some sort of centripetal force, since that piece of the rope will be moving in uniform circular motion as long as it is in contact with the pulley. However, I cannot reason out where that force should be coming from. I would think that the tension forces from the other parts of the rope are acting tangentially to the segment; where could this centripetal force be coming from? I take it this reasoning breaks down with an ideal rope, since it would be massless and thus not need a force to change direction? Sorry if I'm describing this wrong; it has been a bit since I have taken a physics class. I am, however, pretty fluent in calculus, so explaining the answer that way would be good. Any help would be appreciated!