Theoretical Definition and 999 Threads

Does the real vacuum pressure/underpressure depends only on the amount of impurities? In the case of theoretical Torricelli vacuum test, when no purities left in the vacuum: Is the vacuum 0Pa at 1m height (with 760mm of Hg) and also the same at 10m height (also with 760mm of Hg) of the test...

Hello. https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.1970.0021 The Singularities of Gravitational Collapse and Cosmology The above paper by Hawking and Penrose is presented in the form of a mathematical proof. To my knowledge the predictions it makes about the initial cosmological...

What I’m looking for is some new avenue of physics for a scientist in the Star Wars galaxy to be studying. They probably know what dark matter and dark energy are since Starkiller Base is powered by it. I’m sure they know about how the universe began, why it’s expanding and what it’s fate is...

I'm a student from the UK, completing a degree in theoretical physics. I'm interested in pursuing graduate opportunities in both the UK and the US. Of course, I am much more familiar with the 'UK standard' for graduate studies, in that the areas I want to pursue can fall into either the maths...

...Or even based on logic? I understand that it is expected that there might be a Universal Speed Limit and that this seems with extremely high probability to coincide with the speed of em transmission in a vacuum. This is borne out by experimentation and observation. Are there any other...

In "The Theoretical Minimum" (the one on classical mechanics), on page 218, the authors write a Lagrangian $$L=\frac m 2 (\dot r^2 +r^2\dot \theta ^2)+\frac {GMm} r$$ They then apply the Euler-Lagrange equation ##\frac d {dt}\frac {dL} {d\dot r}=\frac {dL} {dr}## (I know there should be...

Hi. The #1 complaint about the Greiner series are the typos. It's a shame how it undermines the potential of this series which is, otherwise, highly acclaimed. Do you know where errata for any of these volumes can be found? Or perhaps those who have read some of the books could share their own...

I would like to ask if anyone has been admitted to a graduate school(US) straight to 2nd year after a theoretical masters MSc degree in the UK. I am asking because I would really like to study in the US, preferably on top universities but I don't want to waste another year taking essentially...

I'm a 4th year MPhys student currently finishing my undergrad. I will be attending a theoretical masters course next year at Kings. I have been declined by Imperial and Cambridge so I have started to get a little worried about my future. Even though I have been declined this year, is there any...

Hi! I found interesting post here: https://electronics.stackexchange.com/questions/325762/how-efficient-are-leds However, it only gives the final results and not the steps he made. I tried to learn the formulas on wikipedia on my own but I couldn't figure out what variables need to have what...

So, basically I need a roadmap of the math required for nuclear theory. I've completed Calc (1-3) and teaching myself ODE. My roadmap currently is PDE, Complex Analysis, Linear Algebra and Numerical methods. I'm going to work through Arfkens 2nd edition of math methods. Any thing else I should...

Mentor Note -- Thread moved from the technical forums, so no Homework Template is shown. So, we've conducted an experiment on resistors in a circuit. The theoretical calculation was based of on E-24 series color band table and the measured resistance of the resistor was measured by a meter...

Hey Everyone. So basically I'm having tonnes of anxiety about my future and would like a bit of a reality check on where I stand and what I will be able to achieve. I go to one of the best universities in the US for undergrad Physics, yet my GPA is on the lower side (3.1). This university was...

Are the standards of studying/teaching methods same across different branches of theoretical physics like particle, astronomy and cosmology? For example we observe a lot of tours, events and conferences in institutes of astronomy and astrophysics, whereas particle and cosmologists are mostly...

So I had a topic which I would like to fact check from an informed scientific source. Basically there is an argument about whether or not an object that naturally exists in a fourth dimensional space, would by default have more than countably infinite times the energy of a 3 dimensional Object...

Hello, My question is what types of data analysis can I perform on a set of theoretical and experimental results? For example, I have v(x) = cos(x) and I plot my observed data to v(x). Thanks!

I'm a physics and math major, going into my 3rd year. Suppose I want to do research in theoretical aspects of condensed matter. What would be the mathematics I should be learning as an undergraduate? Here is a rundown of courses I'm considering taking next year: Abstract Algebra: it seems a...

I am worried that I am passionate about physics and yearn for a career in physics(through theoretical physics), and by a career I mean a placement in a prestigious institute and then be part of leading physics, but would that require sacrificing my entire 20s and even 30s or can I can get all...

Hey PF, In 1 month I am going to start my Bs.c thesis. I already "have" a mentor that is willing to supervise me and a topic. The topic is Bohmian Mechanics. I know its disliked, but that's not why I am asking this question. Tbh I'm not a great student, if I don't like something I will put...

so, assuming that you know all of the aspects of your theoretical generator, apart from the voltage and current, how would you work it out. I know that it is possible, but i can't find anything that I understand, or is even valid online. There should be some equations i can use to work it all...

Hi guys, I find it hard to decide what to work on. To give some background, I am a bachelor student and I want to work in theoretical research. I talked with a professor (he is the chief of the theory department) at my uni about this and he expects me to find a topic or an area of research for...

Is medical physics as informative as normal physics in terms of the courses I'll do in the University and can it be used as a pathway into medicine and surgery?

I took great comfort reading a New Scientist article on the Perimeter Institute, Canada where top theoretical physicists pass the day. They asked four how they get through the day. Two replies gave me great comfort: Asimina Arvanitaki I spend most of my time being confused about things and...

I am working on the same problem as a previous post, but he already marked it as answered and did not post a solution. https://www.physicsforums.com/threads/sphere-with-non-uniform-charge-density.938117/ I am curious as to a method of finding the ##k## and substituting into the electric...

Hi! I'm currently in my second year of a five year integrated masters degree in physics. When applying, I chose to study just plain physics as I didn't really know what I wanted to do and I didn't want to limit my options. However, for the past year and a half, and honestly before that too, I've...

I am doing some research into atmospheric energy harvesting. To design a proper feasibility experiment, I need to establish some theoretical baselines. I see a lot of values for the field strength for example, tossed about from various papers. However, there does not seem to be a standard...

Hi all, I am interested in advancing my education in theoretical physics, specifically topics concerning quantum field theories and quantum gravity. However, I have a somewhat rocky background as an early undergrad and while my Master's degree was achieved with great success in the classroom...

I was watching a video about physics that said people who want to study theoretical physics but do not want to study things like electromagnetism, thermodynamics, experimental physics, etc, should study math, then take some classes in theoretical physics. This way, you could study your favorite...

Hello All, I have the following question in one of my tutorials. I need some help in resolving this. Background: A manufacturing company developed 40000 new drugs and they need to be tested. Question The QA checks on the previous batches of drugs found that — it is 4 times more likely that a...

I am a 12th grader and I am having trouble choosing what I want to major in. My biggest interest is string theory/ quantum field theory/ theory of everything/ particle physics (math intensive theoretical physics). But the problems with getting a physics degree are 1) getting a phd takes a long...

It goes without saying that theoretical physics has over the years become overrun with countless distinct - yet sometimes curiously very similar - theories, in some cases even dozens of directly competing theories. Within the foundations things can get far worse once we start to run into...

Hi, I’m just wondering about this: Are there any theoretical reasons why physical laws take the form of 2nd order (in time) differential equations? Or is it just observed to be that way? Are there ANY laws (even in a limited context) which are 3rd (or higher) order in time?

Hello! I am currently applying for graduate schools in the USA and during my undergraduate career I was mainly involved in Dark Matter research. However, my research focused on testing different models (experimentally or using numerical simulations) and doing some basic calculations, basically...

I’m having lots of trouble in my honors physics class with the theoretical homework problems that are assigned. The entire concept of learning to solve things theoretically, and then applying it is brand new to me. I’m decent at figuring out the applied problems, but pure theory stumps me. I...

Hi, I am an aspiring Theoretical Physicist. I've heard that you need to know many programming languages to become a Physicist, but I have never learned a single programming language in my life and I am 16-17 years old now. Is there any chance of me still becoming one? Is there anything I can do...

In my post that I have been ranting on trying to figure out how to solve things on everyday occurrences. Which was titled "Mass of a Piston" That is to say, can you use physics on the spot to calculate a golf swing that projects a ball off a cliff that you have never seen before. You don't know...

Need to come up with specifications for a capacitor that can hold 20,000 or more amps How many joules or watts or how much energy can this theoretical capacitor hold how many farads, what would the current be and how many volts could it tolerate, how to increase volt tolerance. how to increase...

I've been thinking about this problem and would like some clarification regarding the value of the divergence at a theoretical point charge. My logic so far: Because the integral over all space(in spherical coordinates) around the point charge is finite(4pi), then the divergence at r=0 must be...

Hello! What can a first year PhD student (in an American university) do, research related, in the field of Theoretical (mainly high-energy) physics? I know in the USA you need to start research from the first semester of PhD (even if you formally choose a definite field of research at the end of...

I always imagine them sitting in their room behind their desks and working on their new theory like Einstein. I suppose most theorists work in groups nowadays to be more efficient but do these lonely workers still exist and are they supported financially or they're working in their free time?

Hello! Is there a book (any kind of written collection) about mathematical tricks for complex problems (in both math and theoretical physics). Over time I have encountered several nice and impressive tricks to simplify apparently difficult problems and I was wondering if someone gathered them in...

This is a theoretical question that may not be rooted in reality. I hope this was the right section. Please clear up all misunderstandings. Since dark matter can’t emit light, could it be possible that dark matter is ionized matter? I always thought you needed electrons to emit light. Then that...

Theoretical Physics should belong in the math department to then collaborate with the physics department on new mathematical theories within physics. I can't accept that theoretical physics could really be considered a branch of just physics. I can only see theoretical physics being 95% math and...

I was just wondering which out of the 2 courses would be more beneficial for me as I am interested in Astronomy, Astrophysics, and Cosmology: A senior level course in Optics or a Senior Level course in Methods of Theoretical Physics (Presumably mathematical methods). Course Descriptions...

Hi all, I'm a theoretical physics hopeful, and I've had a couple of major setbacks in my undergraduate studies. I'm thinking of whether I should pursue a career in TP, or reconsider doing physics entirely. My background: I've always had an interest in Physics. I got a bronze medal from...

So I'm attempting to write a scientifically accurate story and i need some help with the planets characteristics. I have a few things set up already and need some educated guesses and ideas for how the rest will work. So to start with what i have: Planet name: Remvale Radius:~8370 miles Gravity...

Homework Statement The first exercise in Susskind and Hrabovsky's The Theoretical Minimum is one that, in the words of Susskind, "is designed to make you think, more than it is designed to test you." The exercise asks: Homework Equations In the prior paragraph, the authors define the notion...

Does anyone know if or when Dr Susskind is coming out with a “ Theoretical Minimum Quantum Field Theory “ ?

I am wondering if anybody knows how to calculate the theoretical relative permittivity of a molecule (1) using the theoretical configuration and values that are easily accessible (2). I am also wondering what the technique would be. In my pharmaceutical reaction class and also O-chem 2 we have...

I’m a young very ambitious student who would like to embrace a project. As a third year undergrad I feel pretty alone. My fellow colleagues are not very forward thinking nor want to do anything besides pass the exams. Are there any platforms/associations for young theoretical physicists...