What is Physics: Definition and 993 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. M

    I General relativity - covariant superconductivity, Meissner effect

    I am doing a project where the final scope is to find an extra operator to include in the proca lagrangian. When finding the new version of this lagrangian i'll be able to use the Euler-Lagrange equation to find the laws of motion for a photon accounting for that particular extra operator. I...
  2. mtv65

    A S-duality in Physics and Fourier Transforms

    In many articles, authors compare S-duality in physics to Fourier transforms. For example: Joseph Polchinski, in his article "String Duality" (hep-th/9607050v2), writes "Weak/strong duality [...] is similar to a Fourier transform, where a function which becomes spread out in position space...
  3. George Jones

    Why Did Defunding Physics Lead to the Global Financial Crisis?

    Yesterday, physicist Geoff Penington tweeted "In 1993 the Superconducting Supercollider was cancelled. Estimated cost: $8 billion. An exodus of physicists left to Wall Street, bringing fancy maths and dubious risk management. 15 years later the global financial crisis cost ~$20 trillion. This is...
  4. Athenian

    Physics What to do After Graduating with a Physics BS?

    I got one year left in my physics undergraduate education. However, after doing some research on what to do for the future, I began to become increasingly lost on what to do after I graduate. Therefore, I hope the physics community here could provide some insight and advice on the matter. To...
  5. T

    Is the Physics in the Avengers' Shield Collision Scene Accurate?

    Hi everyone, In my physics class, we are doing the Hollywood Physics Project. It's a project where you analyze the physics from a scene in a movie and talk about if it's accurate or not. I chose the scene from the Avengers where Thor strikes Captain America's shield with his hammer. The...
  6. E

    Other Your thoughts about "International Journal of Theoretical Physics"

    A year ago, I asked a question about two journals, both of which were predatory ( https://www.physicsforums.com/threads/are-open-access-journals-legit-for-my-cv.990744/ ). Thanks to the overwhelming advice I have received, I did NOT publish in either of those journals. Right now I am asking a...
  7. PRITAM the cat of Ne

    Engineering Op-Amp circuit output analysis trouble

    THE ANSWER IS GIVEN: 6V, but according to me as the positive terminal is grounded the negative terminal will be virtually grounded (0V), from ohm's law (applying to the two series resistance) it is expected that Vo is 0V! I don't know where I am getting wrong!
  8. Arman777

    A Understanding an Approximation in Statistical Physics

    In a book that I am reading it says $$(V - aw)(V - (N-a)w) \approx (V - Nw/2)^2$$ Where ##V## is the volume of the box, ##N## is the number of the particles and ##w## is the radius of the particle, where each particle is thought as hard spheres. for ##a = [1, N-1]## But I don't understand how...
  9. rocky4920

    Physics Praxis Exam Help and Resources

    Hello, I have been having trouble successfully passing the Physics Praxis 5265 Exam. I am a high school biology teacher and have 30 college credits in Physics. My district wants me to teach Physics and I need to get my certification. Once I pass the praxis I will be able to teach. I have...
  10. R

    Quantum Modern Physics Textbook Recommendations for Top-Tier Universities

    I seek current textbook recommendations for Modern Physics (Relativity, Quantum, Nuclear, Particles), upper undergraduate and graduate level, preferably that which are used at top-tier universities. Suggestions appreciated.
  11. IDontHaveAName

    Admissions Having an A- average in upper division physics course

    Hello, all I'm a rising senior who's about to apply for grad school. However, this year has been a rough year for me as my overall grade has declined a bit, especially in that I did not do well in 3 core major courses: mechanics B and EM II I got a B and STAT MECH B+(sadly, I thought i deserved...
  12. codelieb

    Intro Physics Feynman Lectures on Physics Tape Recordings Online for Free Listening

    Hello, everyone. I've made a number of announcements in this Forum about publications at The Feynman Lectures Website, but this is one I've long anticipated and am particularly happy to make: You can now listen to the original tape recordings of Feynman's famous Caltech Introductory Physics...
  13. K

    I Is physics of living matter an undiscovered territory?

    Is the physics of living matter different from that of non-living matter? If yes, how it is different? What makes it different? Does biophysics present itself as an example of interface between quantum and classical physics? Any information that you think might shed light on the subject will be...
  14. G

    How to sell math/physics textbooks in Europe?

    Hello everyone, I don't know if that's the correct place to ask this (didn't want to pollute the science and math textbooks recommendations), sorry if it is not. I have undergraduate physics and mathematics textbooks that I am trying to sell. I live in Belgium and I bought textbooks...
  15. H

    Other General Masters Advice after Bachelor's Degree in Physics

    I am in the second year of my Physics B.Sc and will soon have to make the decision how to continue from there. My grades are generally good, and I certainly want to continue my education, specifically a Masters. My goal is to be employed in industry, where I would strongly prefer actually...
  16. BalinesePhysicist

    Studying What to do in a gap year to prepare for a Physics + Math degree

    As the title says, I am now in a Coronavirus induced gap year. I have been accepted at a university, which for some reason requires us to do a double major. Hence I chose math as my second major alongside Physics since it has the most overlap, and I'm also very interested in theory. In school, I...
  17. P

    Does "internal force" have 2 meanings in physics?

    My understanding is that gravitational fields produce an "internal force" (weight) on objects and hence gravity cannot change the total mechanical energy of an object. But in a free falling situation there is no other internal force cancelling it out, so it does not seem to be an internal force...
  18. G

    B What Math do I need to learn best for Classical and Quantum Physics?

    I am a 14 year old who is very interested in Physics, especially astrophysics, but I don’t know exactly which math I should study in order to learn more in depth of the field. What is the best thing to learn?
  19. A

    I What part of physics describes what happens just outside of an electron?

    Coulomb's law for three dimensional space is an empirical law that describes the forces between two stationary point charges and is defined as: \vec{F}=\frac{K q_1 q_2 (\vec{r}_1-\vec{r}_2)}{|\vec{r}_1-\vec{r}_2|^3} From Coulomb's law, the magnitude and direction of an electric field produced by...
  20. Limebat

    Newbie Physics Student Asks: Does Vapor to Ice Change Acceleration/Velocity?

    *My bad if this question is a tad ree ree. I've just completed my first year of college and am still inexperienced. I just study physics for fun.* My intuition says the momentum of the water vapor is still conserved during the phase shift, as this question most probably relates to the...
  21. leminn

    Binding energy per nucleon of the nucleus

    How exactly would it then be calculated? Here's what I have tried: proton mass: 1.007276 amu Neutron mass: 1.008665 amu Sulphur-34 mass: 33.9678668 amu Calculation: 1.##(16\cdot1.007276)+(18\cdot1.008665)+(16 \cdot0.000549)=34.28117## 2.##34.28117-33.9678668=0.3133032## 3. 1 atomic mass...
  22. R

    Working on my scientific script on quantum physics (sources for the Casmir effect)

    Summary:: Any good english or german sources for Casimir effect, quantum fluctuations or zero point energy Hello, fellow quantum physicists I am currently writing a detailed physics script for my quantum physics project and I wanted to ask if you know some good internet sources on the theme of...
  23. Falgun

    Geometry "The Geometry of Physics" - Theodore Frankel

    Hello everyone. I was browsing through Amazon and found the aforementioned book by Theodore Frankel. As it is available at a relatively cheap price and covers a TON of material I was considering buying it for future use . Although the author says the prerequisites are only multivariable...
  24. M

    What is Fermat's Theorem on Light?

    Hi, I'm Michael, a high schooler very passionate about physics. My favorite physics theorem is Fermat's Theorem on light. I'm also very into computer science and math. I run a physics blog. I look forward to discussions on physics forum!
  25. vadimuha

    Intro Physics What are some textbooks and problem sets I can use to learn physics?

    I'm looking to pre-calculus physics textbooks with problems sets. I need something as rigorous as possible. Problem sets can be separate from textbooks
  26. yucheng

    Engineering What to read for applied physics (engineering, inventions, designs, patents)?

    I am looking books that are similar to many books/magazines that introduce 'inventions, how things work', but what I am interested is the physics and mathematics behind (specifically formulas, measurements, applied physics, patents?) From the course page of an applied electrodynamics course, it...
  27. S

    Future Nobel laureates in physics?

    Which physicists are most likely to win the Nobel Prize in physics in 2021 and in the coming years?
  28. LuccaP4

    Solid-state Physics: Fermi surface and necks in an FCC structure

    Does anyone have some bibliography about necks in FCC structure Fermi surface? I have to solve this problem and I have no idea how to start. Thanks.
  29. E

    Challenge Physics Challenge: Spherical Ball Rolling on a Rough Sphere | Just for Fun!

    Just for fun! :smile: Feel free to have a go at any of the problems. Problem 1 A spherical ball of radius ##a## and centre ##C## rolls on the rough outer surface of a fixed sphere of radius ##b## and centre ##O##. Show that the radial spin ##\boldsymbol{\omega} \cdot \mathbf{c}## is conserved...
  30. H

    Explaining a Physics Formula in Non-Physics Terms: Answer B

    According to the equation, the answer is B. Since the lecture didn't cover much about it, can someone explain this formula in a less physics way? Thanks.
  31. AryaKimiaghalam

    Programs Top Medical Physics Programs in Texas and Florida

    Hi all, Hope you are all safe and doing well. I recently made a decision to potentially move to the states permanently. I am currently in my fourth year of undergraduate degree in physics at a Canadian university (3.82 cGPA, 3.96 in major) and interested in a career in medical physics. For this...
  32. H

    What to learn to make Physics M.Sc more employable

    I am in the fourth semester of my physics B.Sc and my plan is to hopefully get employed in the semiconductor industry. I was planning to continue with a Masters degree in physics, though I am considering Electrical Engineering for instance, and from what I have gathered, I should try and make...
  33. Falgun

    Studying Computational Skills for Theoretical Physics

    I am currently learning to code by auditing Harvard's CS50 course on edx. I am mainly interested in pursuing a theoretical physics major in the future. What I would like to know which scientific computing software/language (as in OCTAVE, SCILAB, FORTRAN, JULIA, etc ) can I learn alongside which...
  34. B

    MHB Physics - Archimedes principle

    Im having trouble with the following question regarding Archimedes principle. A wooden board with an area of 4.55m^2 is dropped into the dead sea (P sea- 1240 kg/m^-3). Calculate the proportion that would float above the surface. (P wood - 812 kg/m^-3). My understanding is that the volume (V...
  35. alya

    Help Needed: Deriving Formula for Computer Undergrad's Final Project

    My mentor wants the derivation of this formula. Me a computer undergrad, unable to figure it out, and my final project are on a halt due to this, any help from the community is greatly appreciated!
  36. N

    Physics Physics Degrees and Semiconductor Industry (IC Design?)

    Hello there, im a physics student from Germany and currently in my second semester of a Bachelor of science. Lately i have become increasingly interested in woking in the Semiconductor Industry and I am currently reading the book "But how do it Know" by J. Clark Scott and i think it is really...
  37. Elon Musk

    Nuclear Physics help please (alpha decay of a Po-216 atom)

    I think that when an atom of polonium (Po-216) is moving slowly enough that it can be considered to be at rest. The Po-216 undergoes alpha decay and becomes lead ( Ph-212 ), via the reaction 깝 Po → Pb + ta. After the decay. the lead atom is moving to the left with speed v. and the alpha particle...
  38. R

    Programs Should I continue on with a physics major?

    Intro: I have just completed my first year in college as a physics major. My first semester I had some issues with scheduling classes so I have only completed the course called Physics 1 despite attending school for a whole year. This course covered one-dimensional and two-dimensional motion...
  39. Amrator

    Other Books on the Physics of Climate Change

    Hello, I'm looking for a textbook on climate change that is not afraid to use advanced physics and mathematics (thermal/statistical physics, differential equations, fluid dynamics, etc.). Too many textbooks on the topic shy away from the mathematics, preventing me from obtaining a deep...
  40. S

    MATLAB How can I plot a Hohmann Transfer Orbit in MATLAB using ode45?

    function Asteroid_Mining clc %Initial conditions g0 = 9.81; %gravity (m/s^2) p = 1.225; %atmospheric density at sea level (kg/m3) Re = 6378; %radius of Earth (km) Ra = 7.431e7; %distance of Bennu from Earth in (km) [August 2023] G = 6.674e-11/1e9; % Gravitational constant (km3/kg.s2) mu =...
  41. Orenshved

    Sci-fi writer in need of futuristic Quantum Physics ideas

    Summary:: Looking for ideas for my book about future QP applications. Hey everyone, I'm writing a sci-fi thriller set 25 years in the future, where my main character and his team are trying to stop an artificial superintelligence that is operating on the world's most powerful quantum...
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