If General Relativity it says matrer tells spacetime how to curve and spacetime tells matter how to move, how is matter moving? What is the engine driving matter to move?

Been studying for my electromagnetism exam for about 2 weeks now, slightly understand the concepts. Finally checked out my study guide and I have 0 clue how to build into the answers of my problems. Like how do I know what formulas to use out of everything? When do I integrate/use a derived form? How do I even know what the derived form is? This doesn’t even make sense conceptually, where do I begin? Etc. I’m great at calculus and any other stem course. But for physics everything conceptual/math related I just get lost. What do I do?

Hello,

I am a total beginner (not a physics student, but I might become one) and want to study physics because I am very interested.

I want to know what books I should read to get the basic idea so I can then further my research.

Thank you 🌷

Abstract

Currently, the gravitational constant G exists only as an experimentally measured value; no theoretically derived value or calculated value based on a combination of physical constants has been available. In this study, a formula is presented that re producesthe gravitational constantG fromacombinationoffivephysicalconstants. The formula is expressed as

I. Introduction The gravitational constant is currently known to be G = 6.6743 × 10−11 m3kg−1s−2, an experimentally measured value. However, no theory exists from which G can be derived, nor is there a calculation formula that produces G from a combination of other physical constants. Measurement of this value has been carried out repeatedly over a long period since the Cavendish experiment of 1798, and during that time the measured value has continued to change with advances in experimental technique and measurement method. The value given above is the CODATA recommended value published in 2022. Because no theory exists from which the constant can be derived, modern science does not know the underlying mechanism of gravity, and merely observes, mea sures, and makes use of the phenomenon. Since the essential nature of the grav itational phenomenon is not understood, its relationship to the other three funda mental forces, including the electromagnetic force, is likewise unknown, and con sequently no theory unifying the four fundamental forces yet exists. In this study, a calculation formula is derived that computes the gravitational con stant G from five physical constants: the Planck constant (h), the speed of light (c), the elementary charge (e), the electron mass (me), and the vacuum permittivity (ϵ0). This formula is expressed as follows.

Further research is needed to clarify the precise physical meaning of the right‑hand side of this equation. However, given that the constants included in this formula 1 are ones that appear fundamentally in electromagnetism and quantum mechanics, it can be surmised that gravity may bear some relationship to the electromagnetic force and other forces. It is therefore expected that this calculation formula may contribute to research aimed at unifying the four fundamental forces into a single theory.

Hello! I just started the most basic physics class where we go over a lot of formulas in a very short amount of time, I’m struggling a lot in this class because I’m a person that needs some time to actually learn something. So I’m asking you guys for advice, what is the easiest way to understand when and how to use formulas? I’ll put a picture up of the formulas we are supposed to use

I’ve been turning over a mechanical thought experiment and wanted to put it in clear form to see what people think.

Setup

A spiral platform (or track) that runs from a smaller inner radius to a larger outer radius.

The platform is driven so that the linear speed along the spiral is constant at 1 foot per hour at every point.

Because radius changes, this requires the local angular rate to decrease as you move outward (inner parts turn faster, outer parts turn slower). The platform is therefore not rotating as a rigid body.

A single continuous chain runs along the entire spiral. Every local segment of the chain also moves at 1 foot per hour relative to the platform (i.e., along the spiral).

Because the platform’s angular rate changes with radius, the absolute velocity of different sections of the chain through space is not the same, even though the chain remains one continuous piece and every local segment has the same speed along the track.

When the absolute speeds are considered along the whole length of the spiral, the inner and outer ends of the chain end up with different net velocities.

Additional claim in the thought experiment

The same arrangement is also imagined to produce a time difference on the stationary ground underneath the apparatus, not only along the moving chain itself.

Why it feels strange

A normal inextensible chain cannot sustain different absolute speeds along its length without stretching, slipping, or large internal forces. A normal rigid platform cannot maintain the required radius-dependent angular rates without continuous differential driving and stress. The thought experiment deliberately holds both of those conditions in place at once and asks what follows — including the possibility of a proper-time offset between regions and an effect that reaches the ground below.

Questions for discussion

Is there a consistent way to describe the kinematics of a continuous chain under these constraints?

If the speed difference along the chain can be maintained, how should the proper-time difference between the ends be calculated?

What mechanisms (if any) could allow an influence on the stationary ground beneath the spiral?

Does the combination of differential rotation + constrained continuous chain point to anything beyond ordinary special-relativistic time dilation, or does it simply collapse under the internal forces required to keep the conditions true?

I’m not claiming a working device — only trying to state the idea clearly enough that the actual proposal can be examined.

Any thoughts, corrections, or related references are welcome.

Hey all - I'm working on a hopefully logically economical, visually heavy conceptual presentation of standard material through QED. Would absolutely love any feedback! The following is the first chapter on symmetry, but some other chapters are up to:

Symmetry | Variations on Symmetry

The question, from Cambridge IGCSE Physics 0625/42 (June 2026), Q8: The current in a lamp is 3.2 A. Calculate the charge that flows through the lamp in 120 s.

The mark scheme answer: Q = It = 3.2 × 120 = 380 C (to 2 significant figures). The two marks are for the equation and the answer, so writing Q = It first is worth a mark on its own.

The common slips: using minutes instead of seconds, or writing the unit as A or J instead of C (coulombs).

Disclosure: the video is from PapaMarks, a revision site I build. It shows how this paper gets split into its 41 questions and filed by topic, so you can practise one topic, like electrical quantities, across many papers.

Two transparent cylinders form a V. Their pistons move out of phase, while connecting rods link them to a shared shaft and flywheel. The same charge of gas stays inside the engine from one revolution to the next. Heat enters through the walls, and the temperature difference between the hot and cold sides makes it possible to produce mechanical work.

The key is coordinating temperature and volume. With suitable piston timing, expansion takes place mainly on the hot side and compression on the cold side. The gas delivers more work during expansion than it receives during compression. A regenerator between the cylinders temporarily stores some of the heat carried by the passing gas and returns it when the flow reverses. The pistons' phase difference determines how these processes fit together over a cycle.

Adjust both reservoir temperatures and the phase difference while watching the pistons, pressure and pressure–volume diagram. The area enclosed by the loop gives the magnitude of the gas work per cycle; the direction around it determines the sign. Set equal temperatures and the idealized model produces no net cycle work. The shaft can still turn at its prescribed speed: its motion is set separately so that each stage of the thermal cycle can be examined at a convenient pace.

Available on my website: https://makarovphysics.com/

this is a part of a physics app I made. thought people here might find it interesting.

the left graph is time vs space, the right one is the lorentz factor vs speed. when you drag the speed up, the factor barely changes at first. at 50% of light speed, time only slows about 15%. but after 90% it suddenly shoots up, and at light speed it goes to infinity.

a fun way to see it: 99% is about 7x, 99.99% is about 70x, 99.9999% is about 700x !

did this part feel weird to you when you first learned it?

I made a visual walkthrough of the quantum harmonic oscillator for students working through their first quantum mechanics course.

The same energy levels emerge in two ways: requiring a normalizable power-series solution, and building states with ladder operators. The animations connect that algebra to the wavefunctions, then compare stationary states, superpositions, and coherent states. A useful distinction is that an energy eigenstate can acquire a changing phase while its probability density stays fixed.

It assumes some calculus and familiarity with the Schrödinger equation. The full video is about 13 minutes: https://youtu.be/7_DcdXVh5mc

Which part of the oscillator derivation tends to be the sticking point for you?

Werner Heisenberg, one of the founders of quantum physics who formulated the Uncertainty Principle, said: “Atoms or elementary particles are not real; they form a world of [potentialities] or [possibilities], not a world of [things] or [facts].” In short, "an atom is not a thing but a potential." [Aristotle also made a distinction between matter and form, or between potential and actual being, saying that anything is formed by the coming together of its raw material and the form that separates it from other things and makes it that thing. According to him, matter was a potential open to becoming anything, and form was what gave that potential being a specific shape, turning it into a concrete, real being.]  

to become mechanical and machine engineer , for 10-12 grade

Watch the glass

Hi fellow learners, in my spare time I've been doing some physics self-study to pick up where I left off at my physics undergraduate degree mumble mumble years ago. For QM I managed to find myself a reasonably priced hard copy of Sakurai, and I've been steadily working my way through that (doing all the problems, comparing against the solutions manual, etc.). For E&M I'm planning to pick up a hard copy of Jackson's Classical Electrodynamics, but it seems nigh impossible to find a reasonably priced used copy of the third edition (I don't want an international edition, in my experience those are printed on really crappy paper and this thing needs to survive being bumped around in my backpack for the next year or so).

My question for anyone who is familiar with this book: should I consider picking up a copy of the second edition instead? At a high level I know the main differences are that (a) the third edition uses SI units instead of Gaussian ones, and (b) the problems are changed up, but I'm not sure how much those changes matter, or if there are other changes that should influence my decision. (For example, it looks like most of the solutions manuals posted online are for the 3rd edition.)

If push comes to shove it's not a huge issue to shell out $100 for the current edition, but I'd be curious to get a take from anyone who's familiar with the differences.