I noticed that fluid mechanics is almost never taught in any physics program, why is that? Isn't it weird and awkward that someone holding a bachelor degree in physics doesn't know anything about fluids, their properties and whatnot?

Let me preface this by saying that I’m a 14 year old from Manchester England. my question is this. As described in specific relativity “E=mc squared” so how come we can only convert from mass to energy and not from energy to mass. In other words why, with enough energ, can we not synthesise mass? Personally, from my limited knowledge, I see no reason we shouldn’t be able to. Even in string theory I see no reason that vibration should not be able to translate from the energy dimension to the mass dimension. Any help with my query would be greatly appreciated

So I have a BS in physics graduated in 2022 and i really want to go back and study physics and start from the consuptual ideas i stopped at when i graduated 4 years ago ( i had reached the level of elementary particles and QED <we touched on it) the math was soo complex (i was good at integrals and calculs at that time now i am kinda rusty) but it is not a big deal math can be learned again but the problem is that i want to buy academic and scinece books that help me self study: general realitivity, string theory and M theory. But not sure what to buy... i searched a little and found these but not sure if it is well be good ( i love David grifiths writing style btw) what u think? I dont mind maths but what i really want is to understand conceptual and math i am not looking for a book that is all maths with no conceptual explaining

- Dr David tong "string theory" writin lectures

- space time and geomatry by sean Carroll

- the elegant universe by brian Greene

Are those good start?

Chinese Physical Society fall meeting

The values a field takes on need to transform in a consistent way under rotations. This means there needs to be an action of SO(3) on whatever space the field is valued in. If you drop the requirement that rotating 360 degrees gets you back to your starting point, you can generalize that to an action of SU(2) on the field values.

Typically it's just sort of assumed that the field is valued in a vector space. With this assumption, you automatically get that your field is valued in a direct sum of irreps of SU(2). Since irreps of SU(2) are defined by their spin, one for each nonnegative half-integer, that gives you an automatic well-defined notion of spin for every vector-valued field.

As far as I know, there's nothing forcing us to consider only vector-valued fields though. The natural first generalization would be to also allow for fields valued in manifolds.

In this context, the natural spin classification of possible fields stops being as obvious, since representation theory doesn't work automatically.

I still wonder though, is there any natural extension of the field notion of spin to manifolds? Among other things, I believe smooth SU(2) actions on manifolds can always be embedded into a representation of SU(2), so using that embedding seems like it could give a natural notion of spin? However, I'm not sure if there are canonical or minimal such embeddings that it would make sense to label manifolds with.

Does anyone know more about this subject, or have places I could look into this?

Btw, I'm not really looking for things like the Wigner classification of particles, since the spins of particles don't necessarily line up with the spins of their fields. I'm also not really looking for a perturbative version of spin, where we only consider the SU(2) action on the tangent space at some point (unless that leads to a global nonperturbative definition I guess).

Is the sun itself white or does it look like a ball of fire?

Hello all,

I’m going to be taking calc I in the spring and then physics I shortly after. I want to self-study between now and when I take physics I, which is anywhere from 8-10 months of time. I’m studying engineering, however, I’m considering the switch to physics.

Throughout the last 2 months and the remaining time of this semester, I have relearned math from pre-algebra, algebra I, algebra II, and precalc w/trig. So that I’m really prepared for calc I advanced algebra & trig. Knowing that physics is very abstract, I wanted to know along my studies of how should i approach math? What procedure should I try to answer math questions in a way that resembles trying to solve physics problems. I want to start the habits that will make me great at solving physics problems now so that when I actually take physics I, I am more than prepared. I feel as if mastering word problems alongside frequent advanced algebra & trig may be the best way to go. I have a whole workbook on algebraic word problems and I would reason that since word problems require you to really deeply think about what the givens are, what you have, what you need, and the steps you need to solve for x. I believe this closely resembles physics problems, but correct me if I’m wrong, I’m prob just naive.

Anyways, I have an algebra-based Giancoli textbook which was the recommendation from my schools physics department given that is what they use. I also am very interested in the MIT open courseware Classical Mechanics course. I find that it’s easier for me to understand math/science through lecture rather textbook. I think doing the MIT course over the next semester and then perhaps Giancoli physics alongside it for extra practice or just start Giancoli after I complete the course is a solid plan.

I’m really excited to learn, struggle, and continue to learn physics. Any advice would be really helpful. Thank you! 🙏🏾

Hi all,

I'm struggling to access the LIGO website, and was wondering if others are having the same issue or just my end- I haven't seen anything about it online

Bit of a pain for some last minute disseration research 😭

Hi all, I know linear algebra is useful in CS but is it in physics? Coz I am in first yr rn and I am studying it. I often wonder how does it useful in physics? I swear to god I will hate it in my whole life whatever what. That’s why I am asking it just want to make sure I don’t need to face it in my whole life again 🥀

I'm in my last year of my undergrad in Physics with a minor in Mathematics, and I'm struggling a lot with burnout and imposter syndrome at the moment. We have to compulsorily take 11 courses every semester (with a strict selection of courses that cannot be modified). Out of these 11, 3 are practicals, 1 is a research project, and the rest are theory courses. I am currently working on 2 research projects as well on topics I like in really nice institutes.

Based on how they scheduled this semester, from 3 October to 3 November, I am giving 23 exams (with 11 Final exams, and a lot of them back to back). Needless to say, I didn't perform very well in quite a few of these exams.

I now have 6 final exams left out of those 23 (I have already given the other 5 finals), and I feel very demotivated. They're all for 2.5 hours, and make up 60 percent of each grade. Moreover, they are back to back from this Wednesday to next Tuesday. Based on how I'm performing, I really feel like physics might be too hard for me. I will be applying for master's next year as well, and I feel horrible about scoring low, especially in my last year.

What can I do? I feel so underprepared, and at the brink of crying all the time. This is genuinely an unreasonable exam schedule. I also feel so burnt out. Does anyone have any advice to deal with this?

TLDR I have 11 courses in one semester, and because of my college's horrible scheduling, I'm giving 23 exams in 30 days. I have 6 left, and they're all back to back from this Wednesday to next Tuesday. How can I deal with burnout, and the subsequent imposter syndrome because of not scoring as well in the other exams? How do I get myself to study?

TL;DR if I put in the same energy (within specified limits), would a computer give the same heat output as a heater? Does that include visual/display and sound output?

I feel like I must be missing a detail, but given that:

- electric heaters are essentially 100% efficient as any wasted energy is also heat

- computers produce wasted energy as heat

- no energy is created or destroyed

So if I put 300W into a computer that's running a stress test, or 300W into a space heater do I get literally the same amount of heat out of both? Does this change if I'm outputting sound?

I'm intentionally ignoring:

- any useful output from the computer (like crypto mining)

- the cost of the hardware (I have old hardware that I could run for the sake of it, but also it's just a thought experiment)

- the useful life of the hardware (it's just a thought experiment)

The semi practical use-case would be: I don't like using gas to heat my house, I'm comfortable coding for home automation, I have a bunch of old computer hardware and a few servers that I run 24/7. I could buy an electric heater for each room and turn it on/off based on the temperature, or I could put a computer in each room and control the workload based on the temperature - inefficiently mining crypto (not expecting to get any return on the crypto itself, but just because it's an way of producing heat that might also produce something "of value") - that would be really easy to turn up and down for the temperature changes required. Sure, the input wattage would be less in the computer version, but that would just lead to more gradual heating.

The actual use-case: I have a Tado heating system which is set to a constant temperature, my electricity is renewable but the gas can't be. Until I get a heat pump I'm pretty comfortable moving bits of the heating to electric, knowing I'll pay more. I have a bunch of computers and servers, but I tend to focus on energy efficiency (like n100/n150). If I intentionally stop focusing on energy efficiency and start putting these computers in rooms where I'd otherwise be using a electric heater is it exactly the same as a low powered electric heater, or just roughly the same?

Essentially: is the computer just a heater with side effects?

Of course, if I put a lot more energy than it's rated for I'll unlock a whole lot more potential energy by burning down my house, I'm not looking for that much efficiency.

Hello everyone, to give some background info I am a Sophomore Community college student paying everything out of pocket. I currently am enrolled into a ME program and i have come to really enjoy physics. I was looking into getting my BS in ME and minor in physics. If I wanted to later pursue a MS/PhD in Physics can it be done? I am getting my BS from UHCL and the constant answers i see is it depends on what classes im exposed to during my undergrad. these are the links if anyone with such experiences can tell me if it is possible. My big passion is renewable energy and environmental.

https://catalog.uhcl.edu/preview_program.php?catoid=24&poid=6588

As I understand it, a system of natural units is defined by setting some set of physical constants equal to "1" and deriving units for various dimensions-of-measurement (length, mass, time, temperature, et cetera) from combinations of those constants. The most famous such system is probably the Planck Units, which use the speed of light c, the gravitational constant G, the Planck constant h, and the Boltzmann constant kB.

However, most of the Planck units are many orders of magnitude away from the scales at which humans usually think; for example, the Planck time-unit is on the order of 10^(-44) seconds, and the Planck temperature-unit is on the order of 10^32 Kelvin (or °C or °F). There are also relatively-large uncertainties in the exact values of the Planck units because the gravitational constant G is very difficult to measure precisely, and the system as originally presented by Max Planck does not include units for every dimension we commonly use (for example, it has no units for electric charge or current).

I'm curious if there is some other set of physical constants which

1. produces units which are closer to human-scale,
2. can all be measured with high precision and accuracy, and
3. can be combined to produce units of every dimension included in the SI system of units.

While bifurcations describe qualitative changes in dynamics (e.g new fixed point appears), the term phase transitions is more static and considers non analytic changes in thermodynamic potentials. But isnt there a relation between them? For example, does every bifurcation cause a phase transition of the respective state space distribution: if I change the dynamics by modifying stability of an attractor this will certainly affect the stationary distribution. And if this distribution is a a physical equilibrium (instead of just any stationary distribution) I can probably relate this change to the partition function which leads me to phase transition.

Now I'm seeing the term “tipping point” more and more often, especially in the field of ecological science, which seems to be nothing but a bifurcation.

Can you explain the relation between these terms?

In advance, sorry for any mistakes I could have made while writing this post, I'm from Argentina and English is my second language.

I've seen videos filmed thousands of kilometers under the sea where we can observe trash like soda cans, plastic wraps and footballs completely recognisable, even though it's under a high pressure.

¿Why does this happen? Things like submarines, people and other stuff can't go that deep unless it's strictly built to withstand that pressure. I mean, even fish from those areas need to be gelatinous to have a form and live there.

I am looking fo a good textbook on differential equations. I found that I now how to solve typical diff eq, but when I have some new ones I struggle a it.

I want aomething to explain why we solve diff equations in a specific way, to describe the math behind, not only to show different solutions.

Basically, I want to develop some intuition regarding solving them.

So, the PhD scholarship application deadline is coming up. I spoke to my supervisor this year about continuing into a PhD, but I'm still unsure if I actually want to do it and it sounds quite difficult to get the scholarship. My project this year is related to dark matter, but honestly, I don't care too much about the dark matter. Although, I've really enjoyed the whole process of building a model and comparing it with experiment. I am also contemplating trying to go for a quantitative finance job as it's also one of my interests. I just wanted to ask if anyone else has had a similar experience and could share their advice. Cheers.

When electricity flows through a wire do the electrons actually move like a fluid, or is it just a fluctuation of voltage that cascades from electron to electron down the wire?

So for a bit of context I am a 1st year electrical engineering student and we are required to create a project for our sem end evaluation and it would also be displayed in our college's tech exhibition. Our lab professor forgot to tell us 😍😍( yes i hate him sm) and he gave us only a 2 day deadline to submit an abstract idea I am genuinely at a loss here of what to do. I don't wanna create a replica of something that's already been done.

So as my post calls out, if you guys have any original idea or a real life problem that you guys would love to see a solution for, i would like it very much. I just want some inspiration.

I wanna do stuff like Japan creating electricity from footsteps lol, smart application based stuffs. But anything related to physics is fine.

I forgot, the project should also correlate with your syllabus which I have tried to shorten (sorry) so you guys can get a basic idea

Electrostatics & Dielectrics: Piezoelectric, ferroelectric, and pyroelectric applications.

Magnetostatics & EM: Induction, Maxwell’s equations, GMR/TMR, biosensors.

Quantum Physics: Photoelectric effect, quantum tunneling (SQUID/tunneling concepts).

Wave Optics: Fresnel/Fraunhofer diffraction, Brewster’s law, Malus’s law, polarization.

Optical Devices & Fibers: Lasers, total internal reflection, fiber optic sensors, attenuation/losses.

I'm an Italian physics student in my second year and I feel so lost.

I've already taken some courses obviously, and I get good marks, but I'm not sure that these developed inside me the physics that they were supposed to do, it seems like I have just memorized them, I feel that a network isn't growing. I'm doubting my future career, whatever it will be. Does anybody feel like me????

Sorry if the text is badly written, English is my second language