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. There is also a version in German.

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.

The article has been published in Zeitschrift für Naturforschung A (2022).
The article also contains the ultimate data availability statement.

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.

*

Three questions are open in fundamental physics.

I*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?

II Are there any *undiscovered
lines* with new physics
– or will F ≤ c^{4}/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.

The limit value
c^{4}/4G ≈ 3.0 · 10^{43} N for the local force has
passed all checks.

It
allows deducing Einstein's field equations and is the shortest known
summary of general relativity.

Because line 3 on maximum
force c^{4}/4G was added to the list only recently,
a separate web page is dedicated to
it.

III*common explanation* for
the 9 lines?

What determines the *principles*
in lines 1 to 5? They imply that
there is a smallest length and time interval. How can this be?

What determines
the *choices* in lines 6 to 9, i.e., the force spectrum, the particle spectrum and the
fundamental constants?

The last four lines contain the *only*
known physics effects *beyond* the standard
model. How do they arise?

Many enjoy searching for answers.

*

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.

*

Combining the 9 lines implies that twice the Planck length
(4G ℏ/c^{3})^{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.

*

The 9 lines also structure the Motion Mountain physics textbook:

Summary | Line | Details | Volume about the topic |

1. Nature dislikes squander: | dW = 0 | Action W=∫L dt is minimized in microscopic motion.
Often, L = E _{kin}-E_{pot}; the lines below
fix the two fundamental Lagrangians L. | Vol. I: Fall, Flow and Heat. |

2. Nature dislikes hurrying: | v ≤ c | Energy speed v is limited by the speed of light c. This invariant implies special relativity and restricts the possible Lagrangians. | Vol. II: Chapters
on Special Relativity. |

3. Nature dislikes excessive force: | F ≤ c^{4}/4G | Force
F is limited by c and the gravitational constant G. This invariant implies
general relativity and, together with lines 1 and 2, fixes its
Lagrangian. (Click for details.) | Vol. II: Chapters
on General Relativity and Cosmology. |

4. Nature dislikes sloth: | W ≥ ℏ | Action W is never smaller than the quantum of action. This invariant implies quantum theory and restricts possible Lagrangians. (Details here.) | Vol. IV: The Quantum of Change. |

5. Nature dislikes perfect order: | S ≥ k ln2 | Entropy S is never smaller than O(1) times the Boltzmann constant k. This invariant implies thermodynamics. | Vol. I (and Vol. VI) |

6. Electric charges are conserved and attract or repel: | U(1) | is the gauge symmetry of electromagnetism. It yields its Lagrangian when combined with lines 1, 2 and 4. | Vol. III: Light, Charges and Brains. |

7. Nuclei show two other types of charges and forces: | SU(3) & broken SU(2) | are the gauge symmetries of the two nuclear interactions, yielding their Lagrangians when combined with lines 1, 2 and 4. | Vol. V: Pleasure, Technology and Stars. |

8. Nature determines the elementary particles: | 18 particles | –
gauge bosons, the Higgs boson, quarks, leptons and the undetected graviton –
with all their quantum numbers, make up everything and, with the
interactions, fix the standard model Lagrangian. | Vol. V: Pleasure, Technology and Stars. |

9. Nature determines the fundamental constants: | Finally, 27 numbers | – dimensions,
cosmological constant, coupling constants, elementary particle mass
ratios, mixing angles – complete the two basic Lagrangians.
They determine all
observations and all colours. | Vol. V: Pleasure, Technology and Stars. |

* *