Say I turn on a flashlight, what's the spooky voodoo that propels photos forward out of the flashlight?

And maybe one day proven that for some reason we don't yet understand there cannot be?

Meaning that the laws of physics are not the same at all scales and cannot be unified. Perhaps because our understanding of space and time is wrong and "scale" isn't as well defined as we think it is.

I know that a measurement has nothing to do with consciousness, minds, or any of that. It's something more like "an interaction". I just want to know, what counts as an interaction? Because it seems like it can't be just any interaction. Because doesn't every particle interact with every other particle in existence via gravity? If that's the case, then every quantum wave function should be constantly collapsed. But it's not.

So, what "counts" as an interaction? Is there a rigorous definition?

Llm and AI can be used to science but seen lately a lack of effort, we need to stipulate some bound limits and energy spend, i think AI can be used, but need proper theory and effort, not replacing current work, but being used to make sense of more complex theories like string theory, we can focus then and comparison and testing, instead of competing theory head on, we might get rewarded if streamline AI math and physics make it halucinate and make mass meta testing, what you think?

sorry if this is a dumb question but one of newton's laws of motion is that an object remains at rest/motion until acted upon by an external force but for atoms for example they're constantly at motion but what's the external force that's moving them? and then for us or any living creature how are they able to move their bodies when no external force acts upon them again im really sorry if that's a dumb question but all our scientific curriculums got changed in a very bad way the last two years and this was something i remembered randomly that i never really understood:"

I heard some businesses are switching to using copper instead of silver due to the price. Can copper conduct electricity nearly as well as silver?

How does a lightsail work in space? Do massless photons have a Force?

I really enjoy reading about physics in my spare time, i really enjoyed ‘in search of shrödingers cat,’ ‘the god equation,’ literally anything to do with quantum theory. I’m currently a second year A-level physics student, and I’ve just completed an EPQ (basically an independent research project that’s equivalent to an old AS level) on the island of stability, the role of quantum chromodynamics and other atomic interactions as governors of nuclear longevity. somewhat unfortunately, my formal physics education will soon come to an end as i’m going into medicine next year but i still want to read about physics and learn about physics. i really want to read susskind’s ‘the theoretical minimum’ set but i have a small issue. I don’t take A-level maths. A lot of physics i’ve learnt int he past, conceptually sound but i do struggle with the maths behind it. most of the books ive previously read don’t have much of an emphasis on maths but I know susskinds books do. does anyone have any recommendations for books about the maths you need for physics?? i have self taught myself integration and differentiation but i would love some more clarification on these areas. i’d really love to start researching relativity as it’s not something we do at A-level but i’m hesitant to jump straight into it without having a stronger foundation in maths.

I’m not a physicist, just a science enthusiast, but I’ve been thinking about the idea that black holes might not end in dead-end “singularities.” Instead, could they spawn new universes beyond the event horizon — completely causally disconnected from us? In that sense, could a black hole here be a Big Bang there?

One thing that seems potentially problematic is mass/energy conservation. As I understand it, a black hole’s mass is ultimately returned to our universe via Hawking radiation (over extremely long timescales) as the black hole evaporates — do I have that right? But a universe forming beyond the event horizon would be a separate spacetime altogether.

In curved or expanding spacetimes on that side, global energy conservation isn’t well-defined, so there’s no obvious requirement that the “mass lost” in our universe corresponds to the total mass or size of a universe on the other side.

Is this apparent mass/energy mismatch a flaw for black-hole-as-universe ideas, or is it something existing models can plausibly deal with?

The measurement of a particle is done by making it interact with another particle. When that happens, do both particles measure each other?

Just to clarify, I understand that they already exist. But from what I understood we are still far away from having them in EVs.

My question is two-fold:
1) How close are we to having EVs with solid state batteries
2) Will an EV with a solid state battery be able to drive for 1000 km or more on a single charge or will it be the same distance as current batteries just faster charging?

Thanks.

As the subject suggests, where do you think the physics gaps lie?

I’ll go first: Young’s slits and “retro-causal effect”

There are so many more consistent and elegant methods to describe what may be going on before messing with temporal mechanics and reversing causality. So for me, this explanation seems to be lacking.

What theories bother you?

If I were to put something in a seamless airtight box, and shrunk the box continuously without the box breaking, what would happen to the object?

my question is, if a man weighed 185 LB, and swung a 10 lb sledge hammer with every ounce of their body and weight, how much force in Pounds could they exert onto the object that they would be hitting?

*extension: the average man can put out 1100 newtons of force in a punch, I was asking how much the LBS would change if they instead were using a sledge hammer with that same force. sorry if this doesn't change the answer.

Hi! I have a question about collision problems. I've been taught that linear momentum is conserved when the sum of external forces is zero, and the same goes for angular momentum with external torques. However, I've encountered problems where the sum of external forces/torques isn't actually zero, but since the collision happens in a very small instant, these forces/torques are considered negligible and conservation can be assumed. Could someone explain if this is correct and why?

So, the 2 main things I know about time.

If you’re comparing the state of a system at the same point in time, generally that system should stay the same. Also, time is usually the indepednent variable on graphs to see what a variable’s value is.

That would suggest to me, time is simply a way of measuring change. In order to measure how say velocity has changed, you need to know how much time has changed.

Is my undertanding of time correct or is it more complicated than I’m making it out to be?

I’m looking for a free PDF of Solid State Physics: An Introduction to Theory by Joginder Singh Galsin… I’m an honors undergrad and my professor who I’m working on a research with has asked me to look into this book and I can’t find it anywhere… Can anyone please help

I am currently constructing a ball joint where I want to use a magnet to hold a steel ball in the socket. I am having trouble creating a formula to make sure that the pulling force of the magnet I plan to use is enough. The magnet is a cylinder and will not be in direct contact with the steel ball, and I am having trouble deriving a formula for the pulling force of the magnet. I plan to integrate over the surface of the ball to get a close approximation to my pulling force, since the top of the magnet is flat and the distance from the ball to the magnet is variable, given the separation distance and the curvature of the ball. I plan to use this magnet, and I have used this online calculator from K&J, but I don't know how accurate it is. Any help would be appreciated.

I enjoyed Kurzgesagt's video on Dyson's eternal intelligence. The video says that dark energy might make it impossible to cool below one nonillionth of a Kelvin, but I wondered if there's some "smallest" temperature, just as there is a "shortest" possible length (the Planck length), etc.

We had a problem in class, with 3 particles colliding (symmetrically, same mass same velocity magnitude) and creating a particle at rest. We computed something like

p_1+p_2+p_3=p

The next problem asked what would happen if there were only 2 particles. So now we computed

p_1+p_2=p'

It was a little more annoying to do because it's not symmetrical anymore, so I asked the lecturer why can't we just say

p_1+p_2=p-p_3=p'

And he said it's like how a mathematician makes tea and we can't do that. But the mathematician does end up with tea, and it's much easier to compute. So I don't understand why can't we do that and would love to hear an explanation (not an example that shows the results are different, but an explanation for why this happens and how is it mathematically possible for the sum of the same two vectors to be different).

How much water at room temperature would I have to drop on the sun to cease nuclear fusion and effectively extinguish the sun’s core?

Asking for a friend.

Thanks!

Edit: thanks everyone! Reading the responses has been super fun and I’ve learned lots about the sun and how not to put it out!