The basic experiment is pretty easy and straightforward. Pull hot water into a syringe, remove air bubbles and then block the hole and pull the plunger back -> it'll start to boil despite being nowhere near 100°C, way below quick pasteurizing temps, because the low pressure allows boiling at way lower temps.

I was curious if that physical effect alone could sterilize the water anyways despite being way lower than typical pasteurizing temps (temp levels the bacteria care about), because boiling the water in cells sounds...not a good time if you're a cell.

If you're not familiar with what I'm trying to say, watch this vid: https://youtube.com/shorts/1e5M8QmNb7Y

It's a straightforward show and tell about water boiling at hot-ish temperature just because of the very low pressure.

I'm just curious if that has any effect on microorganisms (I'd assume so, I don't like getting boiled from the inside - but idk for sure). Could be interesting for temperature sensitive compounds if that works, but idk

As the universe expands how does the new space come into being? What is happening?

When you have a convex lens and you change the focal length the image at some point flips. What happens in-between? How does the image distortion into being upside down? When I try it it seems to bend around itself and I cannot make sense of it.

I wasn't sure of a good way to ask the question in the title.

I know when we see the moon we can see it as different colors because of Rayleigh scattering and various other factors, but why is it when I take a super zoomed in picture of the moon on my phone the moon appears to be off-white and grey?

Even though my is zoomed in the light is traveling the same distance to my camera lens, is the color being automatically corrected or is there more to it than that?

for context, I go to UCSD and study physics here. I am a senior who has already taken all of the necessary classes to graduate except for one lab that will be done this quarter, 3rd year I was taking about 5 classes each quarter solely for physics. That came at the cost of me taking a french G.E. in my 4th year, but I digress. I am currently in a graduate level mechanics class, and have taken more than enough physics electives to complete my major. I have a 3 point something GPA. taking the GRE is simply not within my budget if I enjoy eating food everyday (200 dollars is a lot for a test and some application fees are REALLY expensive), which sucks but that's simply how it is. I'm not asking about the world's leading programs, small fish in an ocean of talent and whatnot, but do I have a shot at getting into a decent one?

Hello everyone. I set up the classic experiment where you place two metronomes on a moving platform (on rollers, in this case, soda cans)

It seems no matter how I start them they sync in antiphase. I know that that should be possible but antiphase is an unstable steady state if I remember correctly. I cannot for the life of me understand why they are never syncing in phase.

I even derived my own (albeit, idealized) equations of motion for the system and simulated it, they synced in-phase, so I don't understand what's the issue now. Any suggestions on what could be going on?

My derived system if curious (latex):

\theta_i'' - \mu\left(1 - \frac{4\theta_i^2}{\theta_0^2}\right)\theta_i' + \omega_i^2 \sin(\theta_i) = -\frac{x''}{l}\cos(\theta_i), \quad i = 1, 2, \ldots, N \\
x'' + \frac{c}{M_{\text{eff}}}x' = -\frac{ml}{M_{\text{eff}}} \sum_{j=1}^{N} \left[ \theta_j''\cos(\theta_j) - (\theta_j')^2\sin(\theta_j) \right]

So I came across two questions where sin^(wt) in the 1st question is being called periodic as well as executing shm whereas in the 2nd question it is being called as periodic only. What’s right and what’s wrong? I mean I asked ai and at first it said that I would be only periodic and when I told it that the ans says otherwise it came up with some explanation I couldn’t understand

Picture: Here

A bodybuilder (red) sits on a chair and let person 1 sit on his lap. The body builder hold onto this person. Then, person 1 let person 2 sit on his lap and then hold onto them. Then, person 2 let person 3 sit on his lap and the hold onto them. This cycle continues until an arbitrary number n of people. Every person uses force F such that the person they hold onto does not fall.

Assume that the chair can't be broken, every person have the same weight, build, and the people can be represented as a square with 1/4 of its part gone. Also that they all put the force at the same place.

If every person sitting on someone's lap is sitting with distance k from the stomach, is there a general equation to calculate the force that the bodybuilder have to exert such that the system is in equilibrium? Or better yet, an equation where we can find the force needed for some person numbered p where p is less than n?

I’ve been doing assignments lately, but I think I’ve been doing all of them wrong so is that what the final average velocity is?

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I have been trying to understand electromagnetic waves, but I am unable to connect the mathematical representation with what actually happens in real life.

As far as I understand, EM waves don't really have a visible “look,” but there should be some physical orientation of the electric and magnetic fields in space, which we represent using sine and cosine functions. What I don't understand is why a wave is represented by a sine function in the first place. Why does it vary like that, and what is actually happening physically?

For example, the electric field produced by a charge decreases as we move farther away from it. So, shouldn't the graph show a decreasing curve as the distance increases? How does a sine function fit into this picture?

In another video, I saw that the sine function represents the strength of the electric or magnetic field. For example, if we consider a time interval from 0 to 2, during the positive half-cycle, the field goes from zero to a maximum value and then returns to zero. During the negative half-cycle, the same thing happens, but in the opposite direction.

If this is correct, does it mean that a charged particle placed at a fixed point experiences an increasing force as the field approaches its peak, followed by a decreasing force, and then a reversal in direction during the negative half-cycle?

But then, why does the field vary like this in the first place? If the source is at a fixed location, shouldn't the field simply decrease as we move farther away from it? I think I might be confusing the variation of the field with time and its variation with distance, but I'm not able to understand the difference intuitively.

What I really want to understand is how an electromagnetic wave actually travels through space. If it travels in a sinusoidal form, what is the physical intuition behind that? Is the sine curve just a way of representing how the field changes, or is there a reason the field naturally varies in this particular way?

I know these might sound like basic questions, but I don't want to just learn the equations without understanding what they actually mean physically.

A friend told me about a paper on an experiment where 3(?) people individually performed a measurement on a superposition and all got different but verifiably correct results. He couldn't remember the title of the paper, though. Does anyone know it?

Since electricity is generated when a magnet and a coil are moved closer together or further apart, can we generate electricity by placing a massive magnet and a coil in space and using the expansion of the universe to increase the distance between them?

I thought resistance was correlated to how thick the wire is, and what material you're using. Thin aluminum is worse than thick copper right? Yet my book says it's Volt ÷ Ampère

Please tell me if I'm wrong, and why in an easy-to-understand way please! /Gen

Given that these correlations cannot be mere coincidence, and that information cannot travel faster than light, how do these two electrons "know" about each other and maintain their correlation?

Hi everyone! I have been wondering for a while now if it would be possible travel into the future (if the future is already pre-determined) and how would that happen scientifically?

And what about multi-verses would that be a possibility too or are all of these theoretical?

Thank you guys for indulging in my curiosities! I appreciate you all. Have a good day or night yall! (^u^)

See this video of me demonstrating. In words, here's what I'm doing. I cover my mouth and nose with my hands, like I'm covering a sneeze the unsanitary way. Then, I whistle. As I whistle, I flutter one of my hands, so I'm quickly slightly opening and closing the cavity created by my hands. I start with a high-frequency whistle, and I slowly slide the whistle down in frequency as I flutter my hand.

At high whistle frequencies, the heard pitch is steady. But at one specific frequency, the heard pitch wavers with the flutter. In other words, when my hands are closed, I hear one pitch, but when my hands are open, it's a slightly different pitch. The same thing happens if I start low and slide up: the pitch is steady except at that one whistle frequency.

What's going on here? I feel like it has something to do with the wavelength of the whistle relative to the size of the cavity, but I don't think it's resonance, because the tone you hear isn't the cavity resonating, like blowing across a bottle. The tone you hear is just the whistle. So why does it change with an open or closed cavity? And why only at that specific frequency?

Hello, I'm an undergraduate physics student, and for one of my classes I've been tasked with interviewing a professional who has a degree in physics and is currently employed in a physics related field outside academia

It would be a casual, about 20-30 minute interview where I mainly ask about your education, career path and work experiences

I'm hoping to schedule the interview for sometime in the near future, whenever it would be most convenient for you. I'm happy to work around your availability.

If anyone would be willing to spare some time, I'd really appreciate it!

I have been studying thermodynamics in my high school and have come to know recently that the Expansion of the universe is an irreversible adiabatic process that its entropy will always increase. But how is that and where is even the energy source that is provided as in temperature Internal energy in general classical thermodynamics processes?

Hi all,

(EDIT: It unfortunately appears that this paper has since been debunked, as environmental artifacts were not properly accounted for. Thank you to everyone involved in the discussion!)

I came across an interesting paper by P.A. Sturrock, E. Fischbach, et al entitled "The case for a solar influence on certain nuclear decay rates".

As we were all taught, nuclear decay is stated to occur at a fixed (probabilistic) rate. However, this paper and a few others by these same authors find significant (~1%) variation in the measured rate of decay based on the earth-sun distance, and also solar activity, leading to them directly suggesting that neutrinos may influence the rate of nuclear decay. As far as I can tell, these papers seem quite conclusive that decay rates are not absolutely constant, but I had never before heard even a hint of discussion regarding this.

As I understand it, their model suggests that the neutrinos may impart kinetic rotations on the nuclei, and thereby modulate the rate of decay. However, I was wondering why this has never been linked with inverse beta decay (a neutrino being absorbed by a nuclei, and instigating a beta decay). It seems like a fairly straightforward connection, but I couldn't find any work suggesting the concept.

Interestingly, my thought process on this was almost the reverse order of the researchers, whereby I came upon the topic by thinking about if/how solar neutrinos could theoretically impact nuclear decay rates, and hypothesised that you may see a change in decay rates (due to IBD) based on Earths' orbital radius. Then my research came across that paper seemingly affirming the pattern.

Does anyone here have more familiarity with either of these concepts, and could point me towards more discussion/research? This has sent me down a real rabbit-hole, but my physics is a little rusty to dig too much further myself. I would also expect a similar effect to occur around nuclear reactors (massive anti-neutrino sources), but I am finding very sparse and mixed results.

Thanks all :)

Imagine you are running, and exactly 1 km away is another person running at the exact same speed. He is running towards the same point as you, but relative to you, he is moving in the opposite direction, and his relative speed is 0 km/h. Find the answer.

I’m enrolled in a research course this term, and my work is on the dynamics of Bloch electron in crystals. It’s mostly semiclassical dynamics, and there’s a lot of work involving Berry curvature.

Marder’s Condensed Matter Physics is one of the assigned books I’ve been given, but because it’s a graduate level book and I don’t have sufficient completed coursework in quantum mechanics, I can’t finish the whole thing myself.

Regardless, I want to get an intuitive understanding of what crystal momentum and Berry curvature are. What is reciprocal space? Is Berry curvature a property of the reciprocal space? What are the closest analogues in classical particle dynamics?

During this process, how do electrons move so easily to another atom? Why don't they fall onto the nucleus, and why don't they collide with each other?

hi, I’m having trouble finding ideas for a high school physics project (it’s a group project) our teacher is very picky and doesn‘t like project topics that would be easier and more efficient for us as students (out of the box ideas if you will)

topics can be anything related to physics but we don’t have a physics lab or any physics equipment so any experiment that involves equipment we the student have to provide it ourselves

topics that we have in our curriculum to give you an idea on what we’re learning:

1/ unit on gravity (basic intro to astrophysics think kepler’s law, cavendish‘s experiment, newton‘s law of universal gravitation, ect)

2/ unit on rotational motion (angular velocity, angular acceleration,torque,ect)

3/ momentum and its conservation (impulse and momentum)

4/ work energy and simple machines

5/ energy and its conservation

6/ thermal energy