Hello, I am currently finishing my Bachelor's degree in Physics and I need to decide which specialization to pursue. Right now, I am primarily considering expert seminars in Biophysics for the remainder of my Bachelor's and then pursuing a Master's in Medical Physics. My main concern is that it might be difficult for individuals with a background in biology related field to find work afterwards. Does anyone have experience with a similar career path (job opportunities, postgraduate studies, salary etc.)? It doesn't matter which country the experience is from, just state it please.

Experices from other fields or from people who have pursued completely different careers after obtaining their Physics degree would also be very helpful. Thank you.

I was scrolling through TikTok and came across a video talking about the number 9 and how it corresponds with the universe.

Could someone please explain what they meant by that?

We see photon as wave or particle depending on the situation.

For example, we see photon as particle in Compton Scattering.

While in double slit experiment, we saw it more as a wave.

How do we know whether the photon will be more wave-like or particle-like before we see the result of an experiment?

Does it depend on the energy? (High energy -> particle, low energy -> wave)

Video for context:  https://www.youtube.com/watch?v=N4k6YyiMJrk

Got hit by a puck while sitting in the front row of a hockey game. Want to know if we can calculate an approximate speed of the puck.

I was wondering what mechanisms one would use to deduce velocity given a video like this.

Additional details: this is an NHL game that took place in the Saddledome.

From seconds 1-3 you can see the puck got through the boards and netting and hits me in the face.

I have got very limited knowledge on physics so apologies if the question is dumb but from my understanding mass bends and warps space, but does it expand it?

Is there an instrument that would allow for interstellar navigation using gravity waves from objects such as stars and planets to calculate location?

I was taught that F = q(v x B) for magnetic force on a moving charge and that F = I(L x B) for current. These equations are the basis for the right hand rule which is basically just the cross product. But how come you switch the fingers for magnetic field and current when a magnetic field induces a current. I believe its called flemings right hand rule, but I haven’t been able to find why its differwnt in the first place and its really confusing me. Any help is appreciated 🙏

EDIT: I was doing a Faradays Law practice problem and realized that the Fleming right hand rule allows you to find the direction of current immediately rather than having to determine direction of flux and all that. Is this the purpose of the fleming right hand rule? Does it have Lenz’s law “built into it”?

https://iai.tv/articles/new-theory-of-gravity-solves-accelerating-universe-claudia-de-rham-auid-2834?_auid=2020

In quantum mechanics, the concept of superposition refers to the feature of quantum systems of being in multiple states at the same time until it is measured. So one might wonder whether two or more particles can occupy - in superposition - the exact same place in space at the exact same time.

"Sadly", the Pauli Exclusion Principle states that no two fermions (particles with half-integer spin, such as electrons) can occupy the same quantum state simultaneously within a quantum system. This principle prohibits the overlap of identical quantum states, including position states.

While particles in a superposition state may exhibit wave-like behavior and spread out over space, they cannot occupy the exact same quantum state simultaneously due to the Pauli Exclusion Principle. Therefore, even if particles are in a superposition of states, they cannot occupy the same position in space at the same time if they are fermions.

But if the Pauli Exclusion Principle were violated, it would mean that particles could occupy the same quantum state / position state simultaneously.

In this scenario,, there would exist a probability, even if astronomically small, to see all particles of the universe converging to the same position in space and time.

Isn't this something that remind the supposed "big bang singularity"?

And if it is true, what are the physical conditions/laws that make the pauli principle possible, and whose absence/alteration could effectively eliminate the pauli principle?

We know the unit of acceleration as distance over time squared. I'm asking myself, it's easy to imagine a distance squared like a plane or any other surface, but when it comes to time, what's themeaning behind, I mean the shape of time on its own is complicated to figure out, I don't even know if it is correct to define "the shape of time", so has anyone ever thought of this?

Ans: μ is independent of Z - what does this mean?

Is time fundamental or emergent?

If time is fundamental then that seems like a very deterministic point of view and I can only conceptualize that as a block universe/4th dimension. Or something along those lines. And that also implies and infinite regress and future. I assume of course. But if time is fundamental then where is quantum mechanics in that exactly? And does that have an effect on how we perceive dimensions or the 4th dimension for example? Or even the block universe?

If time is emergent then does that also change how we perceive dimensions?

I was thinking a beam of laser light passing through a thick medium at an angle. This medium has continuously varying index of refraction (don't know how to make this) so the light path "curves" continuously instead of having a sharp turn. Can I say that light accelerates in this case?

I thought of another example (light in bendy fiber optics cable) but I don't think its the same process.

I worded the title in that strange way intentionally. I’m not asking “is there a minimum time in which a person could receive a lethal dose of radiation” because the answer to that is pretty simple: the limit is the length of time it would take radioactive particles to come into contact with you if you have a strong enough radiation source at a small enough distance. The bit of complication that got me wondering about this is that radioactive sources get very hot. If a human was standing close enough to touch the source, and it was powerful enough to near instantaneously give them a lethal dose, they would likely get incinerated, wouldn’t they? For example, if someone was standing right next to a nuclear fission bomb and it went off, they’d get a lethal dose pretty damn quickly, but would also die immediately from the shock wave and/or heat from the detonation.

So, is there a minimum time of exposure that would cause you to die from radiation and not something else? I feel like a perfect combination of source strength, distance, and maybe heat insulation would yield a minimum time.

From our outside observation, a super massive black hole would take ~ 1-2 x 10^100 years to evaporate. If a hypothetical observer could go to a singularity, their time clock is still 1 second per second, but obviously different from an outside observer. What would be the relative time to an observer (inside the black hole) for the black hole to evaporate? My assumption would be that they would experience the evaporation of the black hole much quicker, would it feel instantaneous? Would you be instantly teleported 2x10^100 years in the future?

Hi, so let me start from the beginning, I'm a high school student doing a science expo project about telescopes and microscopes.

My project is about using light manipulation with the microscope lens and and a source of light to kind of magnify the light into the telescopic lens, thus making it have a better range and or view. The problem is I can't find anything on Google of anything like this and I'm starting to doubt if I should even do this in the first place. I would love if any of you guys can give me some tips or links or whatever so that I can list this in my research plan. I've been trying to find something for a week now. The expo is tomorrow, I thought that if I kept on trying I would find something, but I can't. Also since I can't find any research on this is not helping much for my reference either. I don't even know if this will work in theory, which is the fun of it, I did experiment with alternatives since I don't have access to the needed lenses or components, but I'm still doubtful and I don't want to bring a useless project to the expo. My teacher said it's a good idea though.

Anything is appreciated! Thank you! (I couldn't post this in r/askscience for some reason and I need answers)

I currently have a round unit that is pressured to approx 2.7kPa, which air flow exits via a fixed tube. (Seed delivery from metering unit to soil).

I am looking to reduce the pressure and velocity at the tube exit. The beginning and end of the tube is a fixed diameter (16mm), however a section in the middle can be replaced.

I have considered replacing the middle section of tube with a larger diameter (25mm for example) to reduce the pressure, however would the velocity not increase going back to 16mm diameter at the exit of the tube. What would be a good way to vent excess air but keep some sort of velocity for seed delivery, just not at the original pressure of 2.7kPa?

I tried reading about this and all I can find is that there's no quantum particle to represent it, but I don't understand how it's any different than gravity if that's the consensus.

I don't want to project my opinion on accident (it's uneducated) so I'll stop here. I'm not challenging Nobel Prize winners as much as I'm trying to understand.

My professor said the following:

Fact 1: The GR energy-mom tensor is always symmetric.

Fact 2: The energy-mom tensor from the Noether current need not be symmetric.

Therefore, if we want to relate the two different energy momentum theists, we can add to the symmetric GR energy momentum terms one so-called “improvement terms”. We are allowed to do this because the energy-tensor is not uniquely defined.

My questions are:

1. Why is the energy-tensor not uniquely defined? Does this have something to do with “we only care about energy difference and not about absolute energy values so can shift our energies or add constant energies however we want” or some type of gauge/coordinate transform invariance?

2. How is the interpretation of the GR energy mom tensor different from the interpretation of the Noetherian current energy mom tensor?

3. Could someone elaborate on what these improvement terms are or how to find them?

Hi! I'm trying to find a good textbook or handbook covering the majority of topics pertaining to light, everything from science history, like photoelectric effect or huygens, to some more specific cases, like bragg diffraction and delayed choice. Is there such a gem?

My 11th grade physics teacher said that if you compress a spring with a certain amount of energy, it will weigh slightly more (have more mass) afterwards because E=mc². I understand the idea and the fact that it has more energy that would convert to more mass, but the teacher didn't provide a proof. How is this proved?

In the context of local realism does the idea of ER=EPR or any theory using quantum entanglement to “produce space” itself violate realism? My understanding is that it can violate locality so it can preserve realism. Also would this allow for hidden variables since locality could be violated? Does the theory require hidden variables? Not saying it’s true, just trying to understand it a bit better.

One force can be either a driving force or a resisting force for a moving object. Is there a term which could describe the attribute containing the two states (driving or resisting) of a force? Force direction relative to moving direction?

If I am traveling through space in an inertial frame of reference, and if through some mechanism I experience time dilation in which my clock begins to tick faster compared to when I began my journey, will my progress appear to be slowing down from my perspective?

To elaborate a bit, say as I drift through space I am passing some sort of milestones which I pass once per some number of hours according to my clock, as I experience the time dilation, will more time pass for me between encountering milestones? And if so, would this appear from my perspective as if the distance between milestones was getting larger? Also, to further back up my feeling that things are getting further apart, would light originating from distant sources and therefore from a frame of reference where time was passing slower compared to mine, become more and more red-shifted as I experience this time dilation?

I would love to see if there is someone who can answer this for an advanced undergrad or graduate in physics! Don’t be shy in explaining the physics and math in more detail because that would be appreciated!

I mean it can't be nothing right?

I have been told by a physics researcher in a discussion via email that there are mechanisms of supressing proton decay but he didn't give any details. Can you name any of these mechanisms?

Similarly, he mentioned that spinning or charge black holes can supress Hawking radiation emission. Can they? How?

I’m talking about the one with the future and past light cones.

I'll start by saying that when meaning to write a vector I'll use the ° on the left of the vector.

I haven't done anything about calculus at school, but I understand its basics quite a bit (derivatives, limits, definite and indefinite integrals).

That said, this year (for the ones who want to know, I'm italian and I'm in 10th grade in a technical IT school) in a subject I have the teacher is talking to us about classical electromagnetism.

He showed us two equations relating the force on a linear conductor (F), the current passing through the conductor (I), the induction of the magnetic field in which the conductor is placed (B) and the length of the section of the conductor (L):

ºF = º(I dL)׺B

F = I L B

Thus, the first equation lets us calculate the force vector, while the second one just lets us know the module.

(I dL) in the first equation is considered a vector, even though I isn't a vector, because dL in this case isn't just considered as a differential, but it's a versor and, in the case of a linear conductor, it has the same verse as the current.

I don't really deeply understand what differentials are, though, and when the teacher told me that this dl isn't an infinitesimal variation of L but a finite versor (of length 1), I got the need to solve a curiosity:

in the case that L is of length 1, too, what's the difference between L, the differential dL and the versor dL?