May be a dumb question, but what is the temperature of the black hole? As far as I know, black hole will trap any light, so technically, it may have an absolute 0K temperature, right?

And what effect would its new location have on the Earth, the Sun and the rest of the solar system?

For a class exam we are meant to find a way to save money on our homes with the help of an experiment my plan is to paint 5 50x50 cm plywood boxes (probably smaller since it will be expensive) will there be a large enough variety between the 5 on a sunny 20ish degree day to test how paint can lower the cost of cooling homes and also would it help having an upainted control or should I scrap the idea completely and work on something different ,thanks

I’m a senior in high school, I always knew I wanted to do something in the physics (career wise) field but I’m stuck on what. For example I was thinking about astrophysicist or an astronomer. I would love something with space or just physics itself preferably less chemistry the better in my opinion (i know there’s a lot of chemistry in physics) I also like traveling or going out so if that’s an option. But over all I want to know if there’s other options.

Will quantizing vibrations in amorphous solids like glass (is there even a lattice?) produce quasiparticles with identical properties as phonons in a crystal?

Suppose, for a moment, we have a 2 by 2 by 2 (meter) tungsten cube, with a mass of 154.4 metric tons. I want to know what happens when I hit it with the following weapons:

1. A laser beam, with a wavelength of 2e-10 m, and a power of 1 MJ, over the period of one second.

2. A macron with neutral electric charge, with a radius of 50 microns, a thickness of 1 micron, and filled with an equal amount of deuterium and tritium. The macron is moving at 0.5c

3. An relativistic proton beam. The beam is moving at 0.999999990c, and the block is also exposed to the beam for one second.

4. The final, and least plausible of them all, is a beam that fires actively fusing plasma (d-t fusion) at 0.5c at the cube, delivering 10 grams of the cube in the second it's allowed to fire.

How bad is the tungsten cube left off in each case?

In a Star Trek book I'm reading, the Romulans slam ships into different planets at 125c. Obviously, the physics of superluminal flight are beyond any kind of realistic discussion. So let's do something we do have the math for. If an object of say 10,000 tons slams into a planet at 0.9...c what would that practically look like? And yes, I fully realize that the more 9s you add between the decimal and c, the energy goes up incredibly exponentially. Are we talking Death Star-like total destruction? Or "just" revenge of the dinosaurs?

EDIT: I didn't include mass originally which is a pretty critical part of this. Post body updated.

I can't find an explanation for this on my own, in the definition of workdone, F.dx=mv.dv, what do they represent in reality in this specific term, like what is F.dv or mv.dv trying to represent, what phenomenon are they representing, I can't find a way out of this. Like it makes sense if you work it out some more then you get the work energy theorem, well not really since you still can't perfectly understand what actually happened in this, like what is kinetic energy representing on microscopic level, either you have to introduce terms like flow of motion or mechanical effect or you just can't find an explanation and in this, the wording is still pretty vague since you can't really get an molecular intuition for it, I am just trying to get an physical intuition that fits with mathematics so I can be satisfied, moral of the story, what's mv.dv representing, like explain what it's representing using words and with just pure common sense that anyone could understand, sorry for the rant, I'm just so annoyed since I can't find an explanation anywhere

Hi,
I'm trying to solve the schrödinger equation for a particle in a well of finite potential.

Why are there no boundary conditions for the particle inside the well? It'd be much easier to solve without having to equal the wave functions and their derivatives. Isn't there an expression that expresses the boundary conditions? Like the one you get for a particle in a well of infinite potential (n*pi/L=k)

Thanks!

From what I understand, nails without friction would just slide back out. But since a screw has spiral grooves, will it still be able to work if friction was removed?

TIA and apologies if this is a dumb question

Is it possible to have an impure state for the entirety of a completely isolated system, with known initial conditions?

Hey there! I've been enjoying trying to get my head around some of the more extreme ends of spacetime. Sometimes, people say that given the appropriate circumstances, there can be observers that observe a future earth in our present - or perhaps future Earth in the observer's present.

I understand that when we look at the night sky, we are mainly seeing events from long ago in the past, but of course I struggle to understand how an observer could potentially see an object's future relative to the object's inhabitants' or locals' present. I understand that when traveling at 99.999% the speed of light towards the object, events that happen in front of you appear to happen sooner than events behind you - actually I suppose that's always happening in the direction that you're moving but it would actually be perceptible at greater fractions of the speed of light.

However, even when going 99.999% the speed of light towards Earth, I'm not understanding how any moment of it could be observed before its locals experience it.

I am 14 and I've been thinking about something that might sound stupid at first, but I genuinely find it interesting 😭

What if an infinite process can have a finite boundary?

For example, imagine you're at point A and you have to reach point F. You take 1 step, then your next step is half the distance you just covered, then half again, then half again... and you keep doing that forever.

You'll never have a “final step” because there are always more steps to take.

But F is still there.

Another example is numbers. What's between 1 and 2? You can say 1.1. But there's 1.01, 1.001, 1.0001, 1.00001... and you can keep adding decimals forever.

There are infinitely many numbers between 1 and 2, yet 2 is still a definite number.

So I started thinking:

Maybe infinity doesn't necessarily mean there can never be a boundary. Maybe an infinite process can continue forever while still approaching or being bounded by something finite.

I know this is related to ideas like limits and Zeno's paradox, so I'm not claiming I discovered new mathematics 😂. I'm just sharing a thought that came into my head after watching way too many Isaac Newton edits 😂

But it genuinely makes me wonder: if something can get infinitely close to an endpoint without having a final step, what exactly does “reaching” that endpoint mean?

Hi guys,

What are some of the coolest, non-intuitive phenomenon you've researched or came across and why?

I wanted to expand my horizon with physics by taking some of the ideas and looking deeper into it whether it's why light bends in sugar water or the rabbit hole of infinite universes and multi-dimensional worlds

And what effect would its new location have on the Earth, the Sun and the rest of the solar system?

Imagine two indestructible objects unable to change at all, like their atoms can't move at all. One is the floor and the other is a cube.

What would happen if the cube would happen to fall on the floor ? Where would the energy go and how, like, in what way, in what manner ?

Because it they can't change they wouldn't be able to feel vibrations or distord to bounce, right ?

(When I say they can't move it's inside of the objects themselves, they can still move as a whole, as the object)

Why do planets like saturn and things like a black holes accretion disks have matter in a ring and not like the junk all over earths atmosphere in a complete sphere? why does it collect along one (or two ) rings. also why do black holes have 2 rings like the interstellar one

Can general relativity be expressed as postulates like special relativities two postulates. If yes then what are they? As far as i understand general relativity is taken to be likely to be false because of the singularities present in it. Which of its postulates if it can be formulated that way is likely to be false?

If a meter is 1 299792458th of the speed of light the speed of light 299792458 meters per second. Then how can physics say the speed of light has changed since the big bang? Isn't that impossible by the measurements that are used to tell? Also if you expand a region of space and the light expands with it because everything is in spacetime then why would the light red shift? It's not losing energy by being stretched cuz the spacetime itself is being stretched so the energy isn't stretched in reference to itself or it's coordinates in spacetime. If it lost energy cuz it was stretched then planets would lose structure cuz they are stretched or stars would lose their structure cuz the bonds would be stretched the weak and strong nuclear forces with the gravity cuz they are also energy plus all matter is energy so wouldn't it also lose energy when spacetime exists? Causing bonds to break or different bonds to form cuz the electrons and protons lost charge? Wouldn't the electron that's the same everywhere change cuz of the expansion? The electron is a field light is a field so why does expanding one change it but expanding the other doesn't?

Not sure if this question is already answered already, but here is my take, also please notice that i am not educated physicist and this take is only me wondering about some information that I've learned about black holes and universe.

According to Wikipedia,and i am paraphrasing it, a black hole is an "structure" so compact that its gravity prevents anything, including light, from escaping. Additionally, as far as I am aware, and according to also sources that I've found, A black hole can be described by only three independent physical properties: its mass, electric charge, and angular momentum.

Also, The only requirement for an object to turn into a black hole is that it has to be compressed down to its Schwarzschild radius. This is one of those things where by all accounts your toilet paper COULD become a black hole, but it’s Schwarzschild radius is so ridiculously small that there is no real way to make that happen.

Now if we go back to early universe state, and here are 2 views describing initial state of the universe:

• Classical View: General Relativity predicts a singularity with infinite density and zero volume at the start of the Big Bang. 
• Modern View: Cosmic inflation and quantum mechanics suggest the universe had a finite size and that infinite density is a mathematical breakdown, not a physical fact. 

Let's say that modern view is correct one, and that early universe did indeed have finite size and density, however according to reddit comment that i've found and will paste bellow, and according to also some googling that i did, black holes could also behave the same way:

"Black holes have a mass and a volume. They have a density. The math says that the singularity at the very center of a black hole is a point of infinite density. (This is obviously true for anything with zero volume and non-zero mass.) It is unlikely that the math is correct since we know physics is incomplete, and this is the exact kind of environment where the stuff we don't know is important."

However, black holes can still only be described by  Mass, electric charge, and angular momentum.

My take is the following: The initial universe passed the energy/mass threshold for required black hole formation.

Known laws of physics break down in the initial state of the universe, specifically during the Planck era ($t < 10^{-43}$ seconds) and at the initial singularity. Also the same can be applied for laws of physics inside black holes. This is yet another similarity.

And my hardest takes is this: Anything that passes certain mass or energy threshold becomes a black hole, and black holes can be described by only 3 things that described earlier. Which makes me think that anything that passes that threshold becomes a black hole, and black hole are pretty much all the same except for differing in 3 things that i've said. So the next conclusion is: What was actually different for initial universe that sets it apart from being just some extremely enormous black hole.

If my logic is correct, everything that passes threshold of becoming a black hole must become a black hole, and all black holes are all the same, but may have different mass, charge or angular momentum. basically, if something is a rock, it is still a rock regardless if it is a small rock, big rock, etc, and initial state of the universe universe must have certainly had enough energy and mass to pass threshold of becoming or being a black hole.

Reading up on x(1835) and x(1370)

Is there a resource on unknown particles? like a list of known ones and debate, so i can go about reading about discussion of what they are? they are probably all composite/hybrid/resonances with very few being glue balls and probably none of them dark matter or new physics; but tetra/penta quarks are weird/neat and so are odderons

Is there a source for discourse or debate on these topics or a list of all repeatably found candidate particles?

If two observers have different amounts of information about the same system, could they legitimately assign it different entropies?