This summary of modern physics in one page is written to make the reader wonder, check, and be amazed.
It has been thoroughly checked by thousands of scientists and engineers. (See here on how this is done.)
 

This 9-line summary of textbook physics agrees with 400 years of experiments. Exactly.

The 9 lines, typeset in bold, state that general relativity, the standard model of particle physics and thermodynamics describe all of nature.

The 9 lines contain everything we know about fundamental physics and highlight everything we do not.

Slides for a talk on the 9 lines are found here. pdf There is also a version in German. pdf

A clubhouse podcast on the topic is found here.

Arguments, references and more are in C. Schiller, From maximum force to physics in 9 lines and towards relativistic quantum gravity.   pdf
The article has been published in Zeitschrift für Naturforschung A (2022). The article also contains the ultimate data availability statement.
 

Physics in 9 lines

The 9 lines contain all present knowledge about nature, including all textbook physics and all observations ever made.

The simplicity of the 9 lines and their vast domain of validity are intensely fascinating.

No known observation and no known measurement contradicts these 9 lines, not even in the last significant digit.

Find a single contradicting observation or experiment and become famous.

The 9 lines determine all equations of physics:

Lines 1, 2 and 3, together, uniquely determine special and general relativity, cosmology, the Hilbert Lagrangian and Einstein's field equations, as told here.

Line 5 uniquely implies thermodynamics. The references are given in the pdf linked above.

Lines 1, 2, 4 and 6 to 9, together, uniquely determine quantum field theory and the Lagrangian of the standard model of particle physics, with massive neutrinos and PMNS mixing – often written with a Lagrangian taking a full page in a small font.

The 9 lines show how little math is required to describe nature with high precision.

The 9 lines describe everything that moves - and thus everything that happens in nature.

The 9 lines given above improve the humorous 9 lines found here.

The 9 lines resulted from the work of countless scientists and engineers during 400 years.

Galileo started around the year 1600; line 1 resulted after over 150 years. Line 5 arose from 1824 to 1929, line 6 arose
around 1860, lines 2 and 4 around 1900, line 3 from 1915 to 2002, and lines 7, 8 and 9 from 1936 to 1973.

The 9 lines contain all natural sciences.

They contain physics, chemistry, material science, biology, medicine, geology, astronomy and engineering.

Again: any single observation contradicting the 9 lines will create a sensation.

 
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Three questions are open in fundamental physics.

III    Are all observations in nature described by the 9 lines – or are there phenomena beyond present textbook physics?

For example, to which line does dark matter belong?c4

II    Are there any undiscovered lines with new physics – or will  F ≤ c4/4G  remain the last law of physics?

Explored mainly in the years from 1973 to 2002, the force limit is the law of physics discovered last.4
The limit value c4/4G ≈ 3.0 · 1043 N for the local force has passed all checks.4
It allows deducing Einstein's field equations and is the shortest known summary of general relativity.4
Because line 3 on maximum force c4/4G was added to the list only recently, a separate web page is dedicated to it.c4

IIII    What is the common explanation for the 9 lines?c4

What determines the principles in lines 1 to 5? They imply that there is a smallest length and time interval. How can this be? c4
What determines the choices in lines 6 to 9, i.e., the force spectrum, the particle spectrum and the fundamental constants?c4
The last four lines contain the only known physics effects beyond the standard model. How do they arise?c4

Many enjoy searching for answers.

 
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The best standard model Lagrangian is due to Jim Shifflett; see http://einstein-schrodinger.com/Standard_Model.pdf; a copy is here.
For general relativity, the Hilbert Lagrangian with a cosmological constant is found in many textbooks.

An independent video summary of the standard model and of general relativity, by David Tong, is found at https://www.youtube.com/watch?v=Unl1jXFnzgo&t=1s. The mathematical expression in the video can be seen as a symbolic combination of the 9 lines.
In contrast, the 9 lines are complete and precise. Line 1, the principle of least action, is part of David Tong's mentioned video. Line 1 is also the topic of Sabine Hossenfelder's video on least action at https://www.youtube.com/watch?v=A0da8TEeaeE.

Are the 9 lines a "theory of everything"? They do fulfil all requirements found in tabloids and in popular books. In fact, they do so since the 1970s.
However, the 9 lines are not unified: the origin of lines 6 to 9 has to be clarified first. (An attempt is found here.)

The 9 lines allow measuring progress towards unification, as told in the blog. The blog also has further comments.

 
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Combining the 9 lines implies that twice the Planck length (4G ℏ/c3)1/2 is the smallest length in nature. This needs to be told more often. Conversely, the assumption of continuous space implies a vanishing Planck length. This implies a vanishing quantum of action, or a vanishing gravitational constant, or both. The assumption also implies the lack of most physical measurement units. In other words, exact continuity contradicts all of modern physics. It may be comforting to note that this and all issues due to the combination of gravity and quantum theory disappear if space is seen as effectively continuous, and only so for all lengths longer than twice the Planck length.

The 9 lines and the minimum length imply that the future unified theory has no evolution equation and no Lagrangian. This lack of mathematics in the unified theory is shown in "Relativistic quantum gravity has no evolution equations – only an inequality" at https://www.researchgate.net/publication/364261495.

The 9 lines also provide requirements for the common constituents of space and particles in the future unified theory. In particular, the 9 lines imply that the common constituents are filiform, of Planck radius, and fluctuating. Details about the requirements and their consequences are found in "From maximum force to physics in 9 lines and towards relativistic quantum gravity" at https://www.researchgate.net/publication/365750175. (And an attempt to realize the requirements is found here.)

The 9 lines imply that the complete theory of relativistic quantum gravity – the “theory of everything” or “final theory” – has only two experimental effects: general relativity and the standard model of elementary particle physics with massive neutrinos.

Therefore, the decisive test of any proposed complete theory is the calculation of the values for the elementary particle masses, of the mixing matrices and of the coupling constants.

 
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The 9 lines also structure the Motion Mountain physics textbook:
 

 
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