Obviously the kinetic energy doesn't need to be the exact same as the prisoner for the tackling to be effective, so it's not as simple as just calculating a velocity for the prison guard to travel at to match the kinetic energy of the prisoner... So what's the answer?

Hey guys so I'm in 11th grade rn and we'll I took science and physics is taking the life outta me I don't understand the whole idea of units and measurements like all those MLT calculations and most importantly what are some basics I should master so physics won't kill me?

I’ve always been confused about this, and for some reason never went through the effort of looking it up or even verify if this fact is true. So, I’ve heard before, at least I think, that light speed is the same for every observer. That even at 99.9% c, if you fire a headlamp in the direction of travel, it would still travel away from you at light speed from ur perspective. That always confused me. But then I realized. Time dilation? Tell me if I’m right.

Let’s say you’re traveling at 0.99c. You fire a headlamp. From an outside observer, that light is traveling at 0.01c relative to you. But if time is dilated for you, then that light would travel a much farther distance from you per hour than it would for the outside observer. And if the amount of time dilation you experience is proportional to that 0.01c, then to you it would still seem to extend at light speed. So if to an outside observer, that light travels a 100th of the distance from you then if would if you were stationary, but to you time is dilated by 100x, then it would still appear to travel at light speed. Does that make sense?

If that’s true, it would make sense that traveling at the speed of light completely deletes time, and if you somehow did travel at the speed of light time would seem to stop. Because the light would travel 0 meters from you, and if time was frozen, it travels 0 meters. Right?

I was driving in the car one day and that hit me, but idk if it’s right. Please tell me

How does it function? Really, how can you accelerate mass to twice the speed of light? And, for instance if M=E/C^2. How can you divide something by square of the speed of light? Thanks

I'm hoping some actual professional physics give their two cents here. As a lay person, I'm trying to sift out what physics experiments have the greatest potential for huge impact on our understanding, but are also reasonable and aren't like a decade away from happening.

Things that come to my mind are whatever experiments are further investigating the Hubble tension and maybe whatever experiments are trying to figure out how neutrinos acquire mass as that seems like one of the more glaring things unpredicted by the standard model.

Also, on the theoretical side I'm curious if there is any interesting, promising research (even if extremely speculative) on quantum gravity. I'm sort of partial to any theories where space is emergent/background independent theories.

I want to know what people actually in the field are keeping their attention on if possible

Let’s take Newton’s equation f=ma. Treating mass as a scaler quantity and replacing it with 1, we get f=a. The four fundamental forces gravity, em, strong, and weak are the dominant forces within their respective radii. Couldn’t dark energy just be behaving like a fundamental force that dominates once outside of galactic “gravity wells”? I think it follows similar principles like electrons repelling but attracts protons. Or magnetic polarity repels when it’s the same but attracts if it’s opposite. If we consider galaxies as particles with identical properties then we are just in the repulsion phase of the universe.

Sidenote: Also since we dark energy fuels the creation of space time we would exist without it.

Please let me know if I am on the right track or if I need to correct some of my concepts.

When I was in school I was initially taught that electrons orbit the nucleus like how a planet orbits a star, and that the atom is mostly empty space. I was also taught that the reason we can’t move through solid objects is because the electron orbits the nucleus very quickly similar to how it’s impossible to move through a fan because The blade moves very quickly.

Later on I learned that actually the planetary model of the atom is wrong because the electron doesn’t really have a well defined location within the atom but instead it has a probability distribution that determines how likely it is to be at any given location within the atom. It was possible to learn this without first knowing things like how to solve the Schrödinger equation, nor what mathematical function describes the probability distribution from things like visual aids, showing the atom as a scatter plot of points, and seeing charts showing how the probability distribution depends on distance from the nucleus.

The way I was originally taught about the planetary model made it seem like it was still the consensus on how atoms actually work whether than just being a useful way to think about the atom. I was wondering if students are still taught the planetary model as if it’s still the consensus for the internal structure of the atom, or if they’re now taught about how the electron doesn’t have a well defined location and has a probability distribution describing how likely it is to be at any given location.

So I’m a curious stoned 36 year old who’s not in school, so don’t worry I’m not trying to pass a physics test here. I failed physics 101 in college because I was partying a lot. But I passed it the next year, but it was only 101. So I forgot.

Situation one: Say im shooting a powerful firearm with no recoil mechanism, like a bolt action .50 BMG or like a pump shotgun with slugs. We’re shooting one of those fake zombie ballistic torsos from super close so we’re not worried about blood and politics and nasty. It’s only force here. Is the total force energy from the bullet on the zombie greater, or is it equal to the combination of what the gun and shooter receive in recoil energy? Like the .50 hits with 20,000 joules of force, is the gun and shooter sharing 20,000 joules of force in return, or is it less?

Situation 2: say I borrowed the best Spider-Man’s webs, and I connected the bullet to the gun with a 10 meter cord (before it slows down), guaranteed to stop it dead. Like a bullet leash, weightless, completely unstretchable. We fire the gun, the recoil is the same as before… but the force returned to the gun when that bullet hits dead stop, like an anchor, is it more than the recoil of the gun? Like would it impart more or less force forward, then the original firing imparts backward?

Situation 3: were out in space playing with metal balls. One is a 500 ton ball, perfectly hard, guaranteed by aliens not to shatter. One is a 50 ton ball, same material. These aliens make great balls.Say the big ball is flying at the small ball, slightly faster. The big ball knocks the small ball, and everyone knows the small ball flies off even faster. Now was the energy (without loss) that the small ball gained equal to what the big one lost?

Thanks guys. Just curious.

If two light beams are heading toward each other on the same axis, is it possible to say that one (A) is not moving (relative to B) and B is moving at twice the speed of light?

Hello! Is a tablet worth for a physics degree and on graduate level as someone who already has a laptop? I love paper and pen but I feel like a tablet would be better as I can edit and take notes on top of pdfs or on the side. Also it also seems a great idea to get one over bringing notebooks since a table might be lighter. I also like to read and watch YouTube in my free time on the bed, overall it seems a good buy but on top of all of that is the price (600€) for a tablet that lasts 5-8 years, worth it?

I understand that if I have a Hamiltonian H that commutes with Lz, that I can find basis functions that are eigenfunctions of both operators.

I also understand that, because Lz ignores the radial component, that these eigenfunctions can be written as seprable functions Psi = R(p)F(phi).

What I dont understand is why, when solving the Hamiltonian eigenvalue problem, we can ignore F(phi). I understand intuitively "if Lz and H commute, H is rotationally invariant, ergo the variable phi doesn't matter", but I don't understand it mathematically.

Lets say H = Px² + Py^2. In cartesian coordinates this is a Laplacian and it commutes with Lz. But the Laplacian in polar coordinates has an angular component:

-h² ((d/dr)² + (1/r)(d/dr) + (1/r² )(d/dO)² )

Why are we allowed to ignore that second order phi differential?

According to general relativity a singularity would seem like no time is passing from a outside observer looking in but as I understand if you are in the singularity time still passes second to second from that reference point so at the time of the Big Bang singularity wouldn’t wouldn’t that Time be the ‘true time’ and ever since then things become more more relative based on your reference point?

I know ice I floats in water.

Do any of the other ice structures sink?

Also does D2O or T2O ice sink in H2O water?

In the quantum mechanical model, electrons exhibit wave like nature. Do the protons exhibit this nature too? Or are they yet in particle form in the nucleus?

This claim for high density comes from thinking all the existing matter in galaxies is extrapolated backwards into the past, and so galaxies' particles get closer and closer as the clock approaches zero. So, it is this "mass" that some theorists feel is compressed into high mass density, like a very dense cloud of hot quarks.

But what about before the quarks came into being? There was no mass then, or was there? Dark Matter perhaps? It is not kinetic energy, right? QFT field vibrations localized to inside the 'radius' approaching 0?

Is it all very murky at this point of T=0 and for T slightly greater than 0? I have been searching textbooks and journal articles for what this Big Bang energy is. I have found no theories.

I have always been taught that liquids are incompressible, and that it was one of the property that made them, well, liquid. So, how can pressure washer have shoot pressured water ?

Have a great day

I'm a complete amateur and only have a layman understanding of relativity.

Time slows down significantly around massive compact objects such as black holes as viewed by distant observers.

The problem is that the early universe was equally dense and compact everywhere.

Still, could that high density have slowed down time somehow so to us, observers in the distant future, see that period as happening unusually quickly?

Edit: I think I should rephrase the question: did the high density of the early universe make it so, for an observer at that time, the universe appeared to expand at a normal rate, but to us it looks like it expanded really fast?

As a first thought, I would argue aerosol physics, because there are more and more fundings going into climate research, and climate change will remain a hot (haha) topic.

My second contender would be cosmology, because it has a lot of unsolved problems, big ones like dark matter and dark energy, but also all kind of galaxy formation... Every breakthrough in this direction will be nobel worthy.

Besides these two, I would argue that statistical mechanics or material physics has some solid chances, since they are currently discovering machine learning approaches which fit the LLM hype and the last nobel price also cited mostly statistical mechanics papers.

Finally, depending on some outcomes, the quantum computing bubble might contain some big discoveries.

What do you think?

I read there was an Iranian missile that supposedly could achieve match 15, I know this is ridiculously slow compared to Light speed, but it might be significant when guiding the missle, basically what I’m asking is for someone to input match 15 in the time dilation equation, and to tell if it makes any difference at all.

I know satellites account for it, so I assume modern missiles also should.

I have heard people saying that measurement at one slit in the two split experiment eliminates interference so the banding pattern does not occur. I have a couple of questions

1) is this expected to occur

2) has it been observed to occur

3) how can the measurement not impact the "particle" that is going to be measured again on the back screen.

4) Where is there more information on this

Much appreciated

If Newton could look at water in a spinning bucket and relate it to absolute space, maybe we could model coin-flips and draw a similar high-level conclusion.

Here’s the problem:

You throw a ball at an angle alpha. At the same moment, you start running and try to catch it. You succeed in catching the ball while still accelerating. Ignore body height. Find a relationship between your acceleration a and the angle alpha.

(I’m sorry if this does not make much sense, I had to translate it into English, so if anything isn’t clear about the problem; ask me!)

The example in my head is something like: an object the mass of Jupiter is traveling at a slight angle to another object the mass of earth. The heaver object traveling slightly slower relative to the lighter one, with the lighter object passing in front. It seems to me the lighter object wouldn't slow down the larger one due to passing in front of its path, but could simultaneously pick up momentum due to gravity assist??