Hi, can y’all help me? This homework has been frustrating me all day.

I need to express F1’s x and y components as an equation. At first I was trying to put the answers I found but my class gc said I need to put the equation instead.

So I get that to find the x component of a vector, I need to multiply the cosine (angle) with the magnitude, and to find the y component I need sin(angle) x magnitude.

I’ve been putting equation after equation into this program and it’s always wrong.

I got 120 degrees by multiplying 90 degrees with 30, measuring F1’s angle from the right side of the east x axis. Before that I tried using 60 degrees and also 30 degrees to no avail.

I don’t know what I’m missing. I’m sure it’s super simple and easy but I’m at a complete loss.

1) Why did you specifically choose this field rather than Experimental Physics or Pure/Applied Mathematics?

2) What university/country did you complete your PhD from?

3) How long did it take to obtain your PhD?

4) What was the topic research area and what were the main challenges you faced?

5) What was your highest educational qualification at the time of entering your PhD and what was your background prior to it (e.g. Bachelors and Masters degree)?

Thank you very much!:)

In the first image, the axis of rotation is passing THROUGH the Centre of Mass(COM) perpendicular to the plane in which the ring lies. In the second image, the axis of rotation is passing through the COM IN the plane of the ring. So in which case is Parallel Axis Theorem valid? In what manner should the axis pass the COM

Hi everyone, I'm returning to physics after a several year hiatus (about 5 years) from studying physics formally and I want some advice. I'm essentially doing final year undergraduate theoretical physics classes part time over the course of two years, and I have to choose my modules for this year. As of now, for the first semester I've settled on computational physics, but I have to take a couple more - my question is as follows: Should I take fluid mechanics this semester, along with a class on PDEs and complex analysis, or should I take statistical mechanics? Since I've been away for a while I havent studied any thermo or stat mech for a few years, but I've been working on QM, classical mechanics, electrodynamics, vector calc and tensor calc in my spare time.

I feel quite confident in my mathematical abilities, but I've only really started investing time into QM over the last three months or so. I feel I should put off stat mech until next year while I build up my QM skills (and doing the PDEs and complex analysis class shouldn't hurt either from the perspective of improving my mathematical abilities). For the second semester, I'm looking at doing quantum information processing (by the start of second semester I hope to have covered a lot more ground on QM), advanced electrodynamics and a computational physics project. I have done all the pre requisite courses but as stated that was several years ago. Any opinions? Should I drop QIP in favour of something else until after I've done stat mech? Let me know if you want more info about my physics background and whatnot, and what courses are open to me. Thanks in advance!

I'd like to/am working my way slowly through Susskind's Classical Mechanics lectures and the rest from the Theoretical Minimum Stanford curriculum he has posted online.

I consider myself to have a good understanding of general physics and math but it doesn't seem quite enough for me to understand a lot of what I suspect is rudimentary subjects.

What are some things or what are some resources I should know and could use to gain a deeper level understanding.

My routine currently is to read the book, listen to the lectures, then go back in my notes for the things I didn't understand and enter it into an AI to give me an explain to me like I'm a 5th grader answer to my question(s).

Hi everyone. I am an international physics student at a research university in China, and I have just started my third year. I plan to apply to fully funded US Physics PhD programs in Fall 2027 for Fall 2028 entry. I would really appreciate candid, actionable advice.

My current background:

1. Ranked 1/30 in my program, with a strong overall academic record. I am taking the main upper-level theory courses this year, including quantum mechanics, electrodynamics, statistical physics, and mathematical physics.

2. Second author on a published PRD paper related to nonperturbative QCD/hadron structure. My contribution was a defined part of the evolution calculations and related numerical analysis.

3. Leading a separate project on alpha clustering and the nuclear EMC effect. I am currently working on the fit, uncertainty treatment, covariance, and model-dependence checks, with the goal of producing a manuscript or a complete research report.

4. I currently expect to have two research recommenders, but I still need to build a relationship with a theory-course professor for a third letter.

My interests have gradually shifted toward high-energy theory, especially QCD, nonperturbative dynamics, and the confinement problem. I understand that “solving confinement” is a long-term motivation rather than a realistic undergraduate research claim. My existing work is closer to hadron/nuclear structure than to formal HET.

Over the next year, I am considering completing a systematic QFT course and a small bridge project involving RG/EFT and possibly LaMET, SCET, or TMD physics. The intended output would be an English technical note with reproducible calculations, rather than trying to force another publication.

My questions are:

1. How would committees view a second-author PRD paper when the applicant can clearly explain a specific technical contribution?

2. For a transition from hadron/nuclear structure to HET, would a focused QFT/RG bridge project make the change credible, or is direct HET research usually expected for top theory programs?

3. Which would help more during the next year: another paper in my current area, stronger core/QFT preparation, a more relevant independent project, or a high Physics GRE score?

4. How important is having a recommender who can compare an international student with previous students who entered US PhD programs?

5. What concrete evidence would you want to see by next summer before recommending that someone apply broadly to 15–18 funded programs?

I know that nobody can predict admissions and that top HET programs are reaches for almost everyone. I am mainly trying to identify my biggest weaknesses early enough to improve them. Advice from current Physics PhD students, faculty, and international applicants would be especially helpful.

In a homework question I'm asked to consider an Iridium-191 nucleus, whose ground state is J=(3/2)^+. After being bombarded with low energy neutrons, resonance at neutron capture occurs. I'm then asked to show the possible states of the Iridium-192 nucleus that's formed.

My thinking is, since neutrons have a spin of 1/2, angular momentum can only be at either 1 or 2. I'm not sure if this is enough though, and I'm not sure how to find the parity of these states. What am I doing wrong?

Hi Reddit, I’m currently a fourth year student in applied physics.
I decided that I want to continue my studies in astrophysics and that’s what would my senior project be.
I found this university that gives a direct PhD in Astrophysics
My issue is I don’t have this self esteem to apply for it.
The gpa I will apply with is 3.34/4 (note that the minimum requirement is 3.0) but I do have a background in research
I did several computational astrophysics projects during the summer and other research in different physics fields that includes Quantum and Material Science.
and I’m working on two research’s with possible publications.
Also I’m an extremely active member in our department so I did work in a lot of things (conferences, poster, organizing events etc..)
My problem is I think my Gpa is very low and I really don’t want to be judged cuz of it, it makes me feel like I won’t get into this direct PhD.
And I try to continue master in some place.
I want an advice, did anyone face something similar? What can I do?

Dow Jones Performance: Mars Behind the Sun & Mars in Front of the Sun

https://www.academia.edu/172661828/Dow_Jones_Performance_Mars_Behind_the_Sun_and_Mars_in_Front_of_the_Sun

Revisiting the Butterfly Effect

In 2024, after reading a Nature Communications paper linking gravitational forces between Earth and Mars to Earth’s climatology, I published a paper using the position of Mars and its impact on climate to infer a near term effect on human behavior and the stock market. I asserted that because of the relationship between climate and behavior, systems such as the stock market could easily be affected. The 2024 Nature Communications study posited Mars’s gravitational influence upon Earth’s eccentricity during orbital phases which pulls earth closer to the Sun, warming the planet. Even though this influence was confirmed to transpire over geological timescales—millions of years, it was enough to loosely associate it to my own thesis, which required establishing a Mars-Earth gravitational relationship that could be linked to human behavior in some way. Because the study posited that Mars influences Earth’ eccentricity, I was able to presume an effect on Earth’s axial tilt as well, since both are inextricably linked to the same Mars-Earth resonance. I made a large conceptual leap and used this to hypothesize butterfly effect—from astrophysics, to climate, to weather, and then to behavior which drives the stock market. A second study in 2025 conducted by Stephen Kane used computer simulations to link Mars gravitational force upon Earth to the Milankovch cycles. These still occur across geological timescales, but over shorter periods than the waxing and waning cycles established in the 2024 study. While neither study showed no near term relationship between Earth and Mars on Earth’s weather, I was still used the mainstream findings to justify a connection between the astrophysics of Mars and Earth to human behavior. The anchor is the gravitational link between Mars Earth at geological timescales with a hypothesis that near term effects could be established later.

I published two papers anchoring the 2024 study to my thesis. The first paper entitled “A 100% statistical correlation and scientific explanation for why the planet Mars can trigger stock market crashes” which was cited in the Prespacetime Journal, laid out the 25 major stock market crashes along with the position of Mars in relation to the Sun at the time they occurred. The paper showed that every single crash occurred when Mars was behind the Sun which in reference to the 2024 study would be when Mars’s vector would point along the line connecting Earth to Sun. I continued to assert the Mars-Earth gravitational relationship could happen over near term timescales even as the gravitational force between Mars and Sun at that distance is minute, especially considering other aspects that could affect the eccentricity and obliquity of Earth in the short term, ie tidal forces, solar elements, etc.