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. HighFlyer

    B Springboard physics questions for diving coach at YMCA

    I'm a diving coach at the local YMCA and I want to give a lesson regarding the physics of diving off the board with maximum efficiency. This is the type of diving board with an adjustable fulcrum, basically a lever with one end fixed with bolts. Its been almost 15 years since I've taken a...
  2. warhammer

    Physics Are many Physics Students entering into Astrophysics?

    Maybe it is my present circle but I see a lot of students pursuing Astrophysics and related domains in terms of projects, Master's Degree etc. and I wonder what are the reasons for the same. Is the field extremely "hot" or is it just saturation caused by excessive Pop Sci influence? Full...
  3. D

    At a Crossroads Between STEM Majors (narrowing interests)

    Hey all, Long time forum lurker here. There's a lot on my mind, but I will do my best to keep it concise: I'm an undergrad chemical engineering student, just starting my junior year. I have found myself at somewhat of a crossroads concerning my career pathway: Originally, my plan was to finish...
  4. T

    I Pickleball Physics -- Player reaction time vs aging

    Out of curiosity, how fast are the hands of the pros? I have timed an exchange between BJ/ALW and JD/JI that occurred at the Baird PPA in September 2022. The ball made the (about) 14 foot trip 11 times over 4.0 seconds, for an average trip time of 363mS (milliseconds). (Average speed of 26.3...
  5. G

    I can't find a PhD in theoretical physics after 6 months of trying

    Hi, I am 25 years old living in EU. I am posting my experience with the objective of getting advice or opinions. I have a bachelor in physics with a thesis on the SM electroweak sector. I have a master again in theoretical physics with a specialization on Hadron Physics ( QFT ). Both of my...
  6. Zalokin

    B Understanding Physics for Coding Collision of 2 Balls

    Hi There! I am quite a beginner at physics and my aim is to apply physics to a computer program which I'm coding. The program consists of 2 balls of equal mass colliding into each other and demonstrating the trajectories after an elastic collision. I have already coded a more basic model...
  7. mathguy_1995

    Programs PhD in pure Maths and... Physics

    Hello, I'm currently a phd candidate in pure maths, doing research in Ergodic Theory (concerning ergodic convergence theorems). When I started studying Ergodic Theory I ran into Statistical Mechanics and I immediately fell in love. I've started studying physics from scratch. As my current...
  8. M

    Mastering Jenga Tower Physics: Calculating Forces and Layers

    My attempt at Q3 yielded: 3a) F = Mu.n = Mu x m x g as a function of layer = Mu x m x g x n x i where n = number of blocks per layer and i = layer number. 3b) From - Fn = n x (LWH) x density x gravity x L/2 = F x d where n = layer number d = (n x L x H) / 2 My attempt at Q4 is there should be...
  9. B

    What fascinating insights can I find on this physics website?

    Hello, it looks like I have a lot of reading to do here. It looks very interesting.
  10. PhysPaig

    Admissions Can I cancel a physics PhD visit day, after they've booked my flight?

    Hello everyone! I have a visit day for a school coming up that they booked my hotel and flight for. I was initially interested in the program, but my partner recently received a dream job offer in Boston. I have been offered a spot at two PhD programs there, so I'll likely pick one of those in...
  11. S

    I My spectacles defy the laws of physics

    For curiosity (obviously not having anything better to do with my time) I turned my spectacles the ’wrong way round’ - so that they were upside down, with the arms pointing outwards - and looked though them. (This gives the correct lens for each eye of course.) The image is noticeably worse...
  12. Demystifier

    Mathematicians' contributions to physics

    Are you suggesting that mathematicians are sometimes better than physicists in spotting the real problems in physics? (Just asking.)
  13. angrymonks

    Building a physics formula database -- Help please

    I'm looking to compile a large online database of physics formulas*. I have yet to find any comprehensive "physics list" that isn't too domain specific or simply scalable. My attempt will be to build it here newtondb.com following and expanding on pldb.com. It will be built using a treebase...
  14. A

    Creating a Contour System: Results

    выбранный контур контура и получившаяся система также показана на фото.
  15. F

    Courses PhD in Physics after getting my MS Physics in the US

    I will start my Master's in Physics next August at San Jose State University. If I decide to start a PhD in Physics once I am done with the Master's, will I still need to take courses at the PhD? Or will I just have to do the research?
  16. L

    B Model rocket physics: Why doesn't the motor go through the nose cone?

    For those who have built those small model rockets, please help me understand a very very simple physics problem that i for some reason do not fully get. Why is it that the motor tube does not have a retention ring on it, to prevent the motor from flying out the nose cone? i know it cant be...
  17. A

    I Is it possible, that one physics law is "Everything is in motion?"

    Is it possible, that one physics law is "Everything is in motion?" (since zero doesnt belong to nature)...if so, does that implies that black holes move?
  18. T

    Classical Comparing Fundamentals & Principles of Physics 11th Edition Textbooks

    I am curious to know if there are any notable differences in the amount and difficulty of the questions between Fundamentals of Physics Extended 11th Edition and Principles of Physics 11th Edition. Additionally, I would like to know if both textbooks treat the theory in the same manner in terms...
  19. hudsonj

    Physics based programming problem sets

    Was wondering if anyone knew of any good resources with programming challenges akin to the website "Project Euler" (about page found here). To be more specific, I'm looking for something consisting of problems centred around physics topics that would require some level of problem solving and...
  20. Graham87

    Radiation Physics - Decay Diagram

    In the solution below it says 22% goes to 0.0309keV. From the diagram above I interpret 22% goes to 0.1298keV with EC(L)/EC(K)=3.0 and not 4.4. Why is that wrong ? Thanks alot!
  21. hudsonj

    Intro Physics Pop-sci books about condensed matter physics or superconductivity?

    I was wondering if anyone knows of any technical pop-sci books about condensed matter physics and/or superconductivity that are at the technical level of something like the "A Very Short Introduction" series or the Feynman lectures. That is, something that goes sufficiently into depth into the...
  22. J

    Are dreams a connection to the multiverse?

    Is it possible that when you dream, you are actually traveling through different realities, and going into the consciousness in another reality? This seems to explain how our dreams can be similar to what we preceive as our "actual" reality, or drastically different. You can also tie this...
  23. B

    A Learning about other experimental areas of physics

    Hello! My research is mainly in atomic and molecular physics but from time to time I come across nice experimental setups, that show promise for my work, from other fields, like chemistry or even high energy physics. I was wondering if there is a more organized way to explore experimental setups...
  24. A

    How Does Changing Fundamental Units Impact Scientific Measurements?

    Hello folks, I am Alex, a guy in his 20s with autism who enjoys science and physics. After a search, I have joined, cos I want to be able to talk with like minded individuals who share the same interest in science as I do. Also, I am currently working on figuring out the inner processes of a...
  25. M

    B What is the “Unknown physics” of the new Kilonovae explosion?

    Scientists recently observed a kilonovae explosion. To their surprise, the explosion is completely spherical. They are saying that this is the cause of unknown physics but I don’t understand why they think unknown physics is causing this. What’s unknown about a perfect spherical explosion? My...
  26. S

    What research fields in physics are you working in?

    Hi everyone. I thought I would pose the question in the title to those on Physics Forums that are currently working in physics research (either as faculty, postdoctoral fellows, or graduate students). I was thinking of setting up a poll, but the last time I had asked a similar question I...
  27. E

    I Research paper and sources investigating Earth's moons

    Hi. I am looking for scientific papers, articles and/or even simulations that investigate how many moons it would be possible for earth to have and maybe modern theories about what these moons can be and look like (i.e what characteristics they have) if they were to exist. I have googled and...
  28. M

    I Understanding Diffraction Condition in Kittle's Intro to Solid State Physics

    I am going over the diffraction condition section in Kittle's Introduction to Solid State Physics physics and I am having a hard time understanding why the phase difference angle for the incident wave is positive while the phase angle difference for the diffracted wave is negative. Thank you...
  29. B

    I Understanding cymatics physics

    Cymatics devices using sand allow us to create shapes with sound. Do you know if those shapes depend on the density and the size of the plate? Thank you
  30. themethetion

    Projectile Motion Using Vectors

    TL;DR Summary: Using vector functions how can I find the minimum average velocity (something greater than 11.86m/s) of a ball if the launch angle is unknown and if I have a point that the object must travel through (11.86, 3.47)? In my assignment, I developed a function for a lob shot...
  31. F

    Magnitude of the Line Charge Density of a Power Line

    Okay so I am a little confused as to where I made a mistake. I couldn't figure out how to program Latex into this website but I attached a file with the work I did and an explanation of my thought process along the way.
  32. cwill53

    I Gradient With Respect to a Set of Coordinates

    In physics there is a notation ##\nabla_i U## to refer to the gradient of the scalar function ##U## with respect to the coordinates of the ##i##-th particle, or whatever the case may be. A question asks me to prove that $$\nabla_1U(\mathbf{r}_1- \mathbf{r}_2 )=-\nabla_2U(\mathbf{r}_1-...
  33. ryanpruette

    Solving a Puzzling Physics Problem: ##15 \pm 3\sqrt{15}##

    So this isn't actually a homework question, it's a question that was on the test I just took and I cannot figure out what I'm doing wrong. I've tried solving it three or four different ways, double checking everything, and I keep getting ##15 + 3\sqrt {15}## or ~26.6, which was not one of the...
  34. D

    B Why is there so much multplication in physics?

    i notice with physics, all the equations are a bunch of scrambled sentences or variables being multiplied together. why the multiplication for everything?
  35. Agongo 4

    Courses Becoming a Biomedical Engineer with a Bsc in Medical Physics

    Can I become a biomedical engineer after completing a Bsc in Medical Physics?
  36. G

    Programs Should I major in Physics & Astronomy or Physics & Math?

    I'm currently in my first year of a combined major in Physics and Astronomy. I'm hoping to study theoretical cosmology, and get a PhD in physics. I've been told it would be wise to get a double major in Physics and Math if I wish to study theory, but would it also be wise to get a combined major...
  37. P

    Easy Physics Calculations with C++: Making it Cross-Platform

    Hi. I wrote a little algorithm that calculates some physics equations for education purposes and it's in C++. I'd like to make it avaiable by creating a website and put that code in it so it either interprets the C++ code or preferrably works with an executable (but then how would it be...
  38. J

    B Car Crash Physics: Deceleration Calculations

    Hi, I was watching a documentary on car crashes and how designs are continually being optimised to keep passengers safe. They were saying how many ‘g’s’ certain crashes were based on crumple zones, seatbelt stretch etc. I was interested to do some number crunching to see how big the...
  39. enigmaticbacon

    How many capybaras does it take to move a Stonehenge rock?

    I’m writing a presentation for younger students explaining how science can help them satiate their curiosity in a fun way. This presentation’s goal is to apply as much science as possible to a ridiculous question in hopes of promoting STEM fields. My example is, how many capybaras --the world’s...
  40. kafka64

    Should I skip labs/experiments for Mathematical Physics program?

    I am attending University of Waterloo and my school will allow me to graduate as a Mathematical Physics major without taking any labs/experiment courses (in my school lab is not integrated to physics courses, they are separate courses with separate credits). This could be great because : -...
  41. filo

    Schools Need to decide whether to study Physics or Engineering

    I'm a 17 years old student and I can't choose between studying Physics or Engineering at university, any advice?
  42. DioMiner

    Why does this not work? Projectile Motion problem for Dynamics Class

    TL;DR Summary: I want to mainly figure out where in the problem solving I went wrong. I understand the correct answer (since I looked it up), but to me, it does not make any sense. I am honestly stumped at this point. Online solutions say that my equation y = 0.5774x-0.003354x^2 should...
  43. tanaygupta2000

    Astrophysics research at ISRO in India?

    TL;DR Summary: Theoretical astrophysics research status in ISRO, India I am from India and want to be an astrophysicist serving my nation. Whenever I check about any ISRO news, it is always about some engineering achievements, like the launch vehicle and never about pure theoretical research...
  44. yezia

    Physics Are physicists good in EVERY branch of physics?

    Hi all, I've been pondering over this question for a long time. Of course physicists are specialists in a specific branch (even in those branches, sometimes they specialize themselves in an ultra-specific sub-branch) in which they produce research. I've noticed some professors at my uni...
  45. J

    Nobody understands quantum physics?

    Listen just 1 minute, what does it mean when he said nobody understand quantum mechanics? This sound like comedy
  46. Vectronix

    B Quantum Physics and Atomic Physics

    I think Atomic physics gets into specific examples and experiments but I think I’m probably wrong. So, I have to ask, what is atomic physics and how is it different than quantum physics?
  47. B

    Courses I want a PhD in Physics, having a Bachelor in math

    I know that I need to satisfy the core requirements for a Bachelor's in physics and I have the ability and desire to do it. I live in California.. Here, and I believe almost everywhere, public universities do not allowe enrollment in a second Bachelor's, even online. Private universities are...
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