What is Physics: Definition and 992 Discussions

Physics (from Ancient Greek: φυσική (ἐπιστήμη), romanized: physikḗ (epistḗmē), lit. 'knowledge of nature', from φύσις phýsis 'nature') is the natural science that studies matter, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over much of the past two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the Scientific Revolution in the 17th century these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy.
Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism, solid-state physics, and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.

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  1. F

    I Understanding the physics of chimneys....

    Hello, While watching survival show, I saw a shelter with a fireplace and a chimney and I started thinking how chimneys work. My understanding is that hot air rises and cool air sinks. The fire, confined to the fireplace, heats up the air inside the enclosed space. the hot air rises everywhere...
  2. Lyra

    Programs Exploring a Career in Medical Physics: Advice from PhD Physicists

    Hi All, I am currently doing a PhD in condensed matter physics (experiment) and want to enter medical physics. My ideal job is more like a mix of research and clinical as I want to be able to actually help people. I wonder whether anyone has any suggestions on what I should do. I already have a...
  3. nervousring

    Other Book list for a person with lots of interest in Physics?

    I'm sorry if you get this question often. I wish there was a definitive list at the top of Google searches but there wasn't. I want to learn physics from textbooks. I know basics of Trigonometry. I went through a third of Kline's calculus and found it doable and enjoyable. I also tried Spivak...
  4. E

    Programs I chose math instead of physics. Was it a mistake?

    Long story short, my career goals are to work as a researcher/research scientist in machine learning or to develop models/algorithms for forecasting such as in financial markets or otherwise. Fundamentally, I find think this is quite similar to physics as a science, but that is for another...
  5. T

    Looking for advice on Research Physics Departments

    Hi, I am planning to apply for a PhD in Theoretical Physics. One of my main topic of interest is black holes physics. Would you please be able to advise on the main/ the best/most relevant theoretical physics research departments/groups who have expertise in this field. I am currently looking...
  6. A

    B Is Relativity the Evolution of Classical Physics?

    Can someone please tell me what is Classical Physics? Does Kinematics in One Dimension such as in Physics textbook is considered a "Classical Physics"?
  7. S

    Plumbing Heron's Fountain as a Shower - Seeking advice on the Physics

    Hi all! I have had a sudden inspiration that I could use the Heron's Fountain to make a shower for a campervan, which wouldn't need overhead water tanks (unstable) or electrical pumping! The concept of the heron's fountain is on Wikipedia: Using the diagram above, A would be the shower tray...
  8. G

    Other Advice for Pursuing Physics: My Friend's Story

    Note to moderators and administration: Please move this thread to the appropriate forum/sub-forum, if needed. [Long thread ahead, warning.] I posted an almost identical thread on the Physics GRE forums, but it received hardly any attention...
  9. kimiko333

    Measuring the length of a moving Beam in two different directions

    v_g+v_e=15/t_1 v_g-v_e=10/t_2 v_g=s/(t_1-t_2) But there are too many unknowns. What am I missing?
  10. babylonsashes

    Courses Which math course should I take (as a physics major)?

    I am entering my third year as a physics major, I have space for around 2 math courses this term and I plan on taking 2 from these courses: - Introduction to Analysis II - Functional Analysis - Introduction to the Calculus of Variations - Algebra I I am pretty sure I will take Analysis II...
  11. LCSphysicist

    The current state of physics and comparing it with the past

    Hello. As time goes by, and as i got more near to "moderns problem of physics", i have been noticing something about it. More specifficaly, the vision of the theoretical physicist that i always had is changing. This is not necessarily bad. But here is this: While my initial vision was of...
  12. Demystifier

    I A survey about philosophical aspects of physics

    University of Cambridge has a survey on people opinions about philosophical aspects of physics, most of which are relevant to quantum foundations. https://cambridge.eu.qualtrics.com/jfe/form/SV_5tetnjD2yz4mlBc?fbclid=IwAR30sREcVULBljQrtxnX2FbTfSzS_j7qvXd_UE83oWWeFVqf25W8OFYBjDM I believe many...
  13. E

    Physics Careers in Physics for Equation-Writing Problem-Solvers

    I am an undergrad physics and mathematics double-major. I really enjoy physics for the problem-solving and logical thinking involved in it, and its use of heavy mathematics. Recently, I've gotten into undergrad research but I am not liking it at all, for it is extremely computer-science based...
  14. F

    Four fundamental forces of physics -- explanation for dummies please

    I am not sure if this is the correct place to post so I am very sorry if I am posting in the wrong place. I am looking to have the four fundamental forces of physics explained as simply as possible, I have been doing some online research to try to understand it and I am having a hard time...
  15. M

    Lost in a physics career and willing to return

    Hello, I am remembering that I started a bachelor in physics from 2005/6, 15/16 years ago but I feel I got stuck in that, I graduated in 2012 after many personal struggles to cope with. I loved physics and the idea to find something new and it was hard to cope with the reality that there is a...
  16. kmm

    I Are all symmetries in physics just approximations?

    I came across this video of Leonard Susskind saying that all symmetries in physics are approximations. Unfortunately, I don't have the links on hand, but I have come across other sources of physicists claiming that all symmetries are approximations. My confusion though is that it was my...
  17. Cutter Ketch

    Intro Physics Searching for a Classic Physics Textbook with Autostereograms

    Perhaps this is a fever dream, but I seem to recall a classic Physics textbook that had illustrations of 3D vectors using autostereograms. However, I can't remember which one (or find any evidence that I'm not making this up). I also have the notion that this was very early, well before the...
  18. korwynkim

    Intro Physics General introductory physics books compared to specific books on each topic

    What exactly is the difference in the way an general physics book (Halliday and Resnick, Young and Freedman) covers topics like mechanics, EM, and thermodynamics, compared to respective books like Kleppner and Kolenkow, Griffiths, and Schroeder, other than the amount of material covered for each...
  19. F

    I Gap between introductory physics & solid state physics?

    The left pic is the initial state and the right pics are 2 different descriptions for a metal under electric field E. Are the 2 on the right contradictory and which is correct?
  20. D

    Is Fgy the Same as FN in a System with Two Masses and Friction?

    I am just confused on how to find the normal force/ FN of the first object. My classmates are saying Fgy is the exact same as Fn but I don’t get why Fgy= Fg sin theta Fgy= (20)(9.81) (sin35) Fgy= 112.5 Fgy = FN
  21. N

    Studying How to find challenges to use as a reason to study physics?

    Some days i get the itch to study math other days physics, or computer science. I am trying to break old patters and use my time more wisely. My reasons for study anything is very abstract, cause i don't really need any of these knowledges, and not many really does in todays day of age...
  22. warhammer

    Mean Free Path (Introductory Thermal Physics)

    We have the area of incandescence. Using that we can find the radius and subsequently the diameter. A=π* r^2 -----> r= 0.0025m so d=0.005m Using the formula (given by Clausius as we are not specified in question whether it's a Maxwellian distribution or not) Mean Free Path λ=...
  23. J

    How would you go about studying physics outside of university?

    I think I want to pursue physics, but I can't seem to keep up with the pace of a university class. I also don't like the format. How would you go about doing this?
  24. warhammer

    Question in Thermal Physics (Van der Waals' Equation)

    <Using the hint, I tried to find the van der Waal constants in molar form. Since STP is mentioned, I used the unitary method relationship- 22.4 L=22400cm^3=1 molar V <To find a possible conversion standard between cm^3 and mol; which turned out to be 1cm^3= 4.46*10^-5 mol. <Then I used the...
  25. Demystifier

    Intro Physics Weinberg, Foundations of Modern Physics (2021)

    Steven Weinberg wrote a book again. Did anyone read it? https://www.amazon.com/dp/1108841767/?tag=pfamazon01-20
  26. Philip551

    Studying Advice for preparing for a physics degree

    I am currently in the last year of my high school studies, and I wonder how to best prepare for university. I already have a solid coding base, having currently enrolled in a Python for physics course. I also am studying further maths, something like Calculus 2 in the US. How do you believe a...
  27. S

    MHB Momentum of Falling Ball X & Ball Y: A Physics Puzzle

    Ball X has mass 0.03kg. It falls vertically from rest from a window that is 30 m above the ground. Ball Y has mass 0.01kg. At the same time that Ball X starts to fall, Ball Y is projected vertically upwards from ground level directly towards Ball X. The initial speed of Ball Y is 20 m/s...
  28. M

    I General relativistic comparison to Newtonian physics

    Let's say a small object orbits around massive object at some distance in perfectly circular orbit. In Newtonian physics the force acted upon orbiting body is: Force = m1 * orbital_speed^2 / distance = G * (m1*m2) / r^2 for an object of 1kg orbiting a body of 2*30^kg at the distance of 1.521 *...
  29. J

    A Derek Muller and UCLA Prof. Alexander Kusenko -- Downwind Physics Wager

    Derek Muller is the Veritasium YouTube channel host and he had a wager against UCLA professor Alexander Kusenko on whether a unpowered car going downwind can go faster than the wind. Derek Muller said it can go faster than the wind, while Alexander Kusenko said it only seems that way because...
  30. MidgetDwarf

    Relativity Question Regarding Different Editions of Spacetime Physics by Wheeler

    Greetings! I have misplaced my copy of Spacetime Physics by Wheeler (1966 ed/red cover) and wanted to read it again. Was wondering if there is a major difference between the earlier blue hardback?
  31. Delta2

    I Bicycle physics: Keeping balanced....

    So my main question is why we maintain balance easily when the bicycle has some horizontal velocity, but it isn't the same when bicycle is at rest. The best answer I could find at the web is that when the bicycle wheels rotate, essentially they form gyroscopes and gyroscopes resist the change...
  32. Menna_Ali

    How Hard is it to find a research job with a Master's degree in Physics?

    Hello everyone, ever since I was little I wanted to go into the research field, I have a bachelor degree in physics but I actually wanted to major in engineering because I am more of a doer and I enjoy experimenting with things on hand, but I had to major in physics because in my country (Egypt)...
  33. R

    Physics 'challenge' type problems, High School (16-18) level

    Hi all I've long been a fan of the nrich site for maths and in recent years it has started to add a section on physics here. I also like IsaacPhysics although I haven't used it much in the past year so am still trying to get used to the new layout. I'm looking for other resources along this...
  34. ergospherical

    Physics Summer Physics Placements UK - Too Late in Year?

    Where do I look for Summer placements [UK based] that are vaguely related to my degree [physics]? As it stands I'm going to spend the next two and a half months in Tesco if I can't find anything, which is fine but probably won't count for much in the future. Is it too late by this point in the...
  35. Passers_by

    Help for self-studying physics

    How did you find PF?: The Internet search I tend to forget the proofs of theorems, the derivations of formulas and the content of equations in books. What should I do?
  36. T

    Programs PhD Theoretical Physics - Part 2

    Hello, I have several questions around the application process as well as the organization. 1. Are you aware of any reference website centralizing PhD offers by countries? 2.When it comes to the organization/management/ supervision of a PhD program, I wonder if there are differences by...
  37. J

    Programming Languages used in Graduate School? (quantum, high energy, and nuclear physics)

    Hello, I have 1 undergrad year left and was wondering what the most used programming languages in grad school are. I still don't know which grad school will accept me so I haven't bothered to ask them directly as my application will be in November when I get my GRE scores. I am Interested in...
  38. S

    Programs Can I go from a Physics Bachelor's degree to a Comp Sci Master's?

    Hi, I recently graduated with a Physics and (pure) Math double major but I'm having a bit of a crisis on where to go with my life. I'd like to pursue a Physics PhD, but I'm trying to think of a plan B in case that doesn't work out. I have a general interest in math and programming, so I was...
  39. M

    Studying Necessary maths for undergraduate physics

    I’m starting a physics BSc in the Uk in September, just brushing up on some maths skills before. To speed the process up I’m wondering what maths is not absolutely necessary. I‘m brushing up on all pure ,ash’s and mechanics, but statistics is included in the UK A level too which I am not too...
  40. L

    Help, new physics student looking for advice

    Hi All I have just joined, i am a physics student & very much look forward to hearing more about , i am currently studying at Queen Mary's University in London but look to travel to other areas to learn more about the world of physics, however i was wondering, in 2022 I am looking to go &...
  41. U

    Studying Modern physics after quantum mechanics

    Hello everyone. I am studying physics as a self-study and would like advice on the next topics to study. So far I have been studying: -calculus, linear algebra and basic physics -classical mechanics (from Goldstein's textbook) -classical electrodynamics and special relativity (from Griffiths...
  42. A

    How can I find physics journals near me?

    How can I find physics journal's near by me?
  43. SeaShanty2

    Preparing for Physics Grad School after Math/Comp Sci undergrad

    Hi all, I graduated in 2017 with a B.A. in Mathematics and a Computer Science Minor, but I always wish I had been able to squeeze in more physics classes (I've only taken a very basic intro course at a community college right after high school). I'm currently working in IT and am pretty...
  44. Angelo Pascal

    Geophysics: Fluid Dynamics Problem

    (a) Write down an expression for the velocity field corresponding to uniform rotation. Find the vorticity corresponding to this flow. (b) Consider a small perturbation u' to the state of uniform rotation with angular velocity Ω, which has the form of a plane harmonic wave u'= A exp i(k·x−ω t) +...
  45. M

    Mysteries of hyperspace in Star Wars?

    I was reading the Star Wars YT-1300 Complete Reference Manual and it mentioned that their are some aspects of hyperspace that remain a mystery aside from those well-established facts acknowledged by all competent astrophysicists. What could be one of the main mysteries? I can’t think of any.
  46. Carolus_Rex

    Admissions Where To do my PHD in Physics?

    Okay Background First. I am an undergrad student from india. I want to pursue physics as career ( yeah i know i am being particularly vague here, due to the fact i am still in my first year and haven't really decided on my particular preference under the branch of physics). So I have a...
  47. P

    Physics Grad School (and career) Work-Life Balance: Physics vs Other Fields

    Let’s start things off straight: I LOVE physics. I love the opportunity to understand the world more in depth and mathematically and have had good experiences with all my professors in all of my classes. I have loved the teaching experience I have had as a several-time TA, as well as the deeper...
  48. cemtu

    What makes up a "current" in solid state physics?

    If there is some incoming light that has hit electrons of a N-type doped silicon and broke loose these electrons from their covalent bounds and excited them to the conduction band and also excited the electrons in the donor energy level to the conduction band as well, here we know that, the...
  49. DeathByKugelBlitz

    Physics I have an A-level in physics but no degree, what jobs can I get?

    I have a Foundation Year pass but dropped out of uni in the first year due to COVID making learning go online, which was terrible. All I can find online is stuff you need a degree for but nothing about A-levels
  50. R

    Calculating Potential Energy from Force for Non-Linear Systems

    If I have a force that behaves according to the formula ##F(x)=\alpha x-\beta x^3##, how can I get the potential energy from it? I know that: $$-\frac{\mathrm{d}V(x)}{\mathrm{d}x}=F(x),$$ but what about the limits of the integration?
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