This page is written to make you, the reader, think, disagree, wonder, check and enjoy.

### 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 show everything we know about natural science and everything we do not know about fundamental physics.

An extended version is here: C. Schiller, Present physics in 9 lines - and implications for its future, preprint.

1. Nature dislikes squander: | dW = 0 | Action W=∫L dt is minimized in every motion.
Locally, L = E _{kin}-E_{pot}; the lines below
fix the Lagrangian 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 implies special relativity and its 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 implies general relativity and its Lagrangian. | 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 implies quantum theory. | 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 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. | 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. | Vol. V: Pleasure, Technology and Stars. |

8. Nature determines the elementary particles: | 18 particles | – bosons, quarks and leptons – with their charges and other quantum numbers, make up everything. | Vol. V: Pleasure, Technology and Stars. |

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

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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.

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 given on this page improve the humorous 9 lines found here.

The 9 lines resulted from the work of millions of engineers and scientists 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.

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

For example, to which line do dark matter and dark energy belong exactly?

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 – or is there none?

In particular, what determines the *principles*
in lines 1 to 5?

And 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 unexplained by and thus *beyond* the standard model.

Many enjoy searching for answers and some even dedicate their life to it.

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This image about how to summarize all sciences in 9 lines, free for reuse, might be useful.

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A video summary, by David Tong, of the standard model and of gravitation 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.

The 9 lines allow measuring progress towards unification, as told here, together with more notes.

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