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Hermann Minkowski

Hermann Minkowski

A course in two strands: the short life of the number theorist who learned to see arithmetic as geometry, and the four-dimensional spacetime he gave to relativity in the last year of that life.

Born 22 June 1864, Aleksotas (Kaunas) Died 12 January 1909, Göttingen Raum und Zeit Cologne, 1908 Level advanced undergraduate → graduate
A Minkowski diagram. The light cone (dashed) is the same for every observer. A moving frame tilts its time and space axes symmetrically toward the cone, and the hyperbolas \(c^2t^2-x^2=\text{const}\) mark equal proper time and proper distance.
Lesson 00

How to use this course

Physicists know Hermann Minkowski for one lecture: the 1908 address in Cologne in which space and time were fused into a single four-dimensional world. Mathematicians know him for a whole subject, the geometry of numbers, in which a question about integers is answered by drawing a convex shape and measuring its volume. Both sides of his work rest on one habit of mind. He looked at algebra and saw geometry.

Prerequisites for Part II
  • Linear algebra: determinants, quadratic forms, change of basis.
  • Elementary number theory: congruences, quadratic residues.
  • For Lesson 06, a first course in algebraic number theory (rings of integers, ideals, norms) is helpful.
  • For Lessons 09 and 10, Maxwell’s equations and the basic postulates of special relativity.

Each technical lesson opens with an italic paragraph for the general reader, then gives precise statements, proof sketches and exercises with folded solutions. Lessons 04 to 08 cover number theory and convex geometry (1881–1907). Lessons 09 and 10 cover relativity (1907–1908). Readers interested only in spacetime can read Lessons 09 and 10 on their own.

Reference

Timeline

1864Born 22 June in Aleksotas, near Kovno (now part of Kaunas, Lithuania), then in the Russian Empire. Third son of the merchant Lewin Minkowski and Rachel Taubmann.
1872The family moves to Königsberg, East Prussia.
1880April: enters the University of Königsberg. Begins a lifelong friendship with David Hilbert.
1882–83Three semesters at Berlin, from the winter semester 1882–83.
18832 April: shares the Paris Academy’s Grand Prix des Sciences Mathématiques with Henry Smith, for work on quadratic forms.
1885Doctorate at Königsberg under Ferdinand von Lindemann, on quadratic forms.
1887Habilitation and Privatdozent at Bonn.
1892Extraordinary professor at Bonn.
1894Returns to Königsberg; takes over Hilbert’s chair when Hilbert leaves for Göttingen in 1895.
1896Professor at the Eidgenössisches Polytechnikum in Zürich, colleague of Adolf Hurwitz. First part of Geometrie der Zahlen. Albert Einstein attends his courses.
1897Marries Auguste Adler in Strasbourg. Helps organize the first International Congress of Mathematicians in Zürich.
1902Moves to a new chair created for him at Göttingen at Hilbert’s urging.
1904ICM Heidelberg lecture Zur Geometrie der Zahlen, introducing the question-mark function.
1905Seminar on electron theory with Hilbert. Paper completing the reduction theory of positive quadratic forms.
1907Diophantische Approximationen. 5 November: lecture on the principle of relativity to the Göttingen Mathematical Society. 21 December: presents the Grundgleichungen paper.
190821 September: Raum und Zeit at the 80th Assembly of German Natural Scientists and Physicians in Cologne. December: Max Born joins him in Göttingen.
1909Dies 12 January in Göttingen of a ruptured appendix, aged 44.
1910–11Complete Geometrie der Zahlen; Gesammelte Abhandlungen edited by Hilbert with Andreas Speiser and Hermann Weyl.
Part I · Formation
Lesson 01

Kovno and Königsberg, 1864–1882

Hermann Minkowski was born on 22 June 1864 in Aleksotas, a small town across the Neman river from Kovno, today a district of Kaunas in Lithuania. The region belonged to the Russian Empire. His parents, Lewin Minkowski and Rachel Taubmann, were Jewish. Lewin was a merchant. Hermann was the third son. The eldest, Max, later ran the family business in Königsberg. The second, Oskar, became a physician and pathologist and in 1889, with Joseph von Mering, showed that removing the pancreas causes diabetes.

In 1872, when Hermann was eight, the family left the Russian Empire, where restrictions on Jews were tightening, and settled in Königsberg in East Prussia. He attended the Altstädtisches Gymnasium, moved quickly through the classes, and read Richard Dedekind, Peter Gustav Lejeune Dirichlet and Carl Friedrich Gauss on his own.

Two friends

He entered the University of Königsberg in April 1880, aged fifteen. Heinrich Weber, then professor there, wrote to Dedekind in 1881 about his exceptional talent. Among the students was David Hilbert, two years older and one semester behind him. The two became inseparable. When Adolf Hurwitz arrived as extraordinary professor in 1884, the three began a habit of daily walks in which, by Hilbert’s later account, they covered every corner of mathematics. Hilbert said that he learned much of his mathematics on those walks. Minkowski spent three semesters at the University of Berlin, from the winter of 1882–83, where his teachers included Leopold Kronecker and Karl Weierstrass.

Lesson 02

The Paris prize and the doctorate, 1881–1885

In 1881 the Paris Academy of Sciences announced its Grand Prix des Sciences Mathématiques for 1883. The problem was to find the number of representations of an integer as a sum of five squares. Gotthold Eisenstein had stated formulas in 1847 without proof. Henry Smith of Oxford had sketched a proof in 1867 in a paper the Academy had overlooked.

Minkowski, seventeen when the problem was set, did far more than was asked. He rebuilt from scratch the theory of quadratic forms in any number of variables with integer coefficients, including the theory of genera, and derived the five-squares formulas as a consequence. Smith reworked his own proofs and submitted them too. On 2 April 1883 the Academy divided the prize between them. Smith had died in February. The award to an unknown eighteen-year-old caused controversy among English mathematicians, who felt Smith’s priority had been slighted. Charles Hermite, by contrast, praised Minkowski’s memoir warmly.

The thesis

Minkowski took his doctorate at Königsberg on 30 July 1885, with Ferdinand von Lindemann, who had proved the transcendence of \(\pi\) three years earlier, as his advisor. The dissertation, Untersuchungen über quadratische Formen, continued the prize memoir: it determined the number of distinct classes in a given genus of forms. This line of work, completed by Carl Ludwig Siegel in the 1930s, is now the Smith–Minkowski–Siegel mass formula. Lesson 04 sets out the ideas.

Lesson 03

Bonn, Königsberg, Zürich, 1887–1902

Minkowski habilitated at Bonn in 1887. His habilitation lecture, on spatial intuition and minima of positive definite quadratic forms, already contains the geometric viewpoint of his later work; it was published only in 1991. At Bonn he also wrote a paper on hydrodynamics (1888), a first sign of interest in physics. He was promoted to extraordinary professor in 1892.

The decisive idea came in 1889–1891. Studying the minima of quadratic forms, Minkowski realised that a positive definite form is an ellipsoid and that the set of integer points is a lattice. Statements about forms then become statements about convex bodies and lattices, and volume becomes the key quantity. He developed this in a series of papers and in Geometrie der Zahlen, whose first part appeared in 1896 (Lessons 05–08).

In 1894 he returned to Königsberg. When Hilbert left for Göttingen in 1895, Minkowski succeeded to his chair. A year later he moved to the Eidgenössisches Polytechnikum (now ETH) in Zürich, where Hurwitz had been professor since 1892. One of the students in his classes from 1896 to 1900 was Albert Einstein, who attended irregularly. Minkowski later remembered him as a lazy student who did not bother with mathematics. Einstein later regretted not having learned more of it.

In 1897 Minkowski married Auguste Adler in Strasbourg. They had two daughters, Lily (born 1898) and Ruth (born 1902). The same year he served on the organizing committee of the first International Congress of Mathematicians, held in Zürich. In January 1900 he urged Hilbert to use his Paris Congress lecture to look forward, by surveying open problems. The result was Hilbert’s list of 23 problems.

Part II · The mathematics and the physics
Lesson 04

Quadratic forms and the local–global idea

For the general reader. Which numbers are sums of two squares? Of five? Questions like these concern quadratic forms, polynomials in which every term has degree two. Minkowski’s first work organised such forms into families called genera and found that a form over the rationals is pinned down by a few simple invariants, one for each prime. That idea, testing a global question one prime at a time, became one of the main principles of modern number theory.

Goals
  • Define equivalence and genus of integral quadratic forms.
  • State the Hasse–Minkowski theorem and use local tests.
  • Understand what the mass formula counts.

Forms, equivalence, genus

An integral quadratic form in \(n\) variables is \(Q(x)=x^{\mathsf T}Ax\) with \(A\) a symmetric matrix and \(Q\) taking integer values. Two forms are equivalent if \(A'=U^{\mathsf T}AU\) for some \(U\in\mathrm{GL}_n(\mathbb Z)\); equivalent forms represent the same integers. The determinant \(\det A\) is an invariant. Two forms are in the same genus if they are equivalent over the real numbers and over the \(p\)-adic integers \(\mathbb Z_p\) for every prime \(p\) (equivalently, modulo every integer). A genus contains finitely many classes.

Rational equivalence

In 1890 Minkowski found complete invariants for equivalence over \(\mathbb Q\): the dimension, the discriminant up to squares, the signature, and one sign-type invariant for each prime. In 1921 Helmut Hasse recast these results in the language of Kurt Hensel’s \(p\)-adic numbers as a local–global principle.

Theorem (Hasse–Minkowski)

A non-degenerate quadratic form \(Q\) with rational coefficients represents 0 non-trivially over \(\mathbb Q\) if and only if it does so over \(\mathbb R\) and over \(\mathbb Q_p\) for every prime \(p\). Two such forms are equivalent over \(\mathbb Q\) if and only if they are equivalent over \(\mathbb R\) and over every \(\mathbb Q_p\).

Over \(\mathbb Q_p\) the question is decided by finitely many congruences, by Hensel’s lemma, so the theorem turns a global question into a checkable list. Every form in five or more variables represents 0 over every \(\mathbb Q_p\). Hence an indefinite rational form in at least five variables always has a non-trivial rational zero (Meyer’s theorem, 1884).

The mass formula

For a positive definite form, the classes \(Q_1,\dots,Q_h\) in a genus have finite automorphism groups \(\mathrm O(Q_i)\). Smith and Minkowski gave a formula for the mass

\[ \sum_{i=1}^{h}\frac{1}{|\mathrm O(Q_i)|}, \]

as a product of local densities over all primes and a factor at infinity. Siegel proved the general version in 1935 and extended it to representation numbers. For the sum of five squares the genus has one class, so the mass formula gives the representation numbers directly, which is how the Paris problem is solved. Minkowski’s original formulas contained errors in the factor at the prime 2, corrected later by others.

Exercise 4.1Show that \(x^2+y^2-3z^2=0\) has no non-trivial rational solution, by finding a prime where it fails locally.

Show solution
Suppose a primitive integer solution exists. Mod 3: \(x^2+y^2\equiv0\). Since \(-1\) is not a square mod 3, this forces \(3\mid x\) and \(3\mid y\). Then \(9\mid 3z^2\), so \(3\mid z\), contradicting primitivity. So the form has no non-trivial zero over \(\mathbb Q_3\), and hence none over \(\mathbb Q\). It does have real zeros, so the obstruction is purely 3-adic.

Exercise 4.2The forms \(x^2+y^2\) and \(x^2+2y^2\) are positive definite of determinants 1 and 2. Show they are not equivalent over \(\mathbb Q\) by a quick invariant, and find a number one represents and the other does not.

Show solution
Over \(\mathbb Q\), equivalent forms have determinants differing by a square factor; \(2/1=2\) is not a rational square, so they are inequivalent. For a concrete difference, \(x^2+y^2\) represents 5, while \(x^2+2y^2=5\) has no integer solution (\(y=0,\pm1\) give \(x^2=5,3\)).

Exercise 4.3For even unimodular positive definite lattices of rank \(n=8\), the mass formula reads \(\displaystyle\sum\frac1{|\mathrm O(L)|}=\frac{|B_4|}{8}\prod_{j=1}^{3}\frac{|B_{2j}|}{4j}\), with Bernoulli numbers \(B_2=\tfrac16,\ B_4=-\tfrac1{30},\ B_6=\tfrac1{42}\). The lattice \(E_8\) has \(|\mathrm O(E_8)|=696{,}729{,}600\). Show that \(E_8\) is the only such lattice up to isometry.

Show solution
The right side is \(\frac{1}{240}\cdot\frac{1}{24}\cdot\frac{1}{240}\cdot\frac{1}{504}=\frac{1}{696{,}729{,}600}\). The term from \(E_8\) alone already equals the whole mass, and every other class would add a positive term. So the genus has exactly one class. The mass formula proves uniqueness without listing a single lattice.
Lesson 05

Lattices and the convex body theorem

For the general reader. Plant a tree at every point with integer coordinates and stand at the origin. If you draw a large enough symmetric, bulging shape around yourself, it must contain another tree. Minkowski turned this simple picture into a precise theorem and used it to prove classical results about sums of squares and rational approximation in a few lines.

Goals
  • Define lattices and their covolume.
  • Prove Minkowski’s convex body theorem via Blichfeldt’s lemma.
  • Derive Fermat’s two-squares theorem, Lagrange’s four-squares theorem and Dirichlet’s approximation theorem.

Lattices

A lattice \(\Lambda\subset\mathbb R^n\) is the set of integer combinations of a basis \(b_1,\dots,b_n\). Its covolume \(\det\Lambda=|\det(b_1,\dots,b_n)|\) is the volume of a fundamental parallelepiped and does not depend on the basis. A sublattice of index \(m\) in \(\mathbb Z^n\) has covolume \(m\).

Convex body theorem (Minkowski, 1889–1896)

Let \(\Lambda\subset\mathbb R^n\) be a lattice and \(K\subset\mathbb R^n\) a convex set, symmetric about the origin (\(x\in K\Rightarrow -x\in K\)). If \(\operatorname{vol}(K)>2^n\det\Lambda\), then \(K\) contains a non-zero point of \(\Lambda\). If \(K\) is also compact, \(\operatorname{vol}(K)\ge2^n\det\Lambda\) suffices.

Proof

Blichfeldt’s lemma. If \(S\) is measurable with \(\operatorname{vol}(S)>\det\Lambda\), there are distinct \(x,y\in S\) with \(x-y\in\Lambda\). Indeed, cut \(S\) along the translates of a fundamental domain \(P\) and slide every piece back into \(P\). The pieces have total volume greater than \(\operatorname{vol}(P)\), so two of them overlap.

The theorem. Apply the lemma to \(S=\tfrac12K\), of volume \(2^{-n}\operatorname{vol}(K)>\det\Lambda\). We get \(x\ne y\) in \(\tfrac12K\) with \(x-y\in\Lambda\). Now \(2x\in K\) and \(-2y\in K\) by symmetry, so their midpoint \(x-y\) lies in \(K\) by convexity. For the compact case apply the strict version to \((1+\varepsilon)K\) and let \(\varepsilon\to0\); a compact set meets the discrete set \(\Lambda\setminus\{0\}\) in finitely many points, so one point works for all \(\varepsilon\).

The constant \(2^n\) is sharp: the open cube \((-1,1)^n\) has volume \(2^n\) and contains no non-zero point of \(\mathbb Z^n\).

Linear forms theorem (Minkowski)

Let \(L_1,\dots,L_n\) be real linear forms on \(\mathbb R^n\) with \(\det(L_i)=\Delta\ne0\), and let \(c_1,\dots,c_n>0\) with \(c_1c_2\cdots c_n\ge|\Delta|\). Then there is \(x\in\mathbb Z^n\setminus\{0\}\) with \(|L_i(x)|\le c_i\) for all \(i\).

The region \(\{|L_i(x)|\le c_i\}\) is a compact symmetric parallelepiped of volume \(2^nc_1\cdots c_n/|\Delta|\ge 2^n\), so the compact theorem applies.

Two squares in one picture

Let \(p\equiv1\pmod4\) be prime, so there is \(u\) with \(u^2\equiv-1\pmod p\). The lattice \(\Lambda=\{(a,b)\in\mathbb Z^2: b\equiv ua \pmod p\}\) has index \(p\), so \(\det\Lambda=p\). The open disk \(a^2+b^2<2p\) has area \(2\pi p>4p\). So it contains \((a,b)\ne0\) in \(\Lambda\). Then \(a^2+b^2\equiv a^2(1+u^2)\equiv0\pmod p\) and \(0<a^2+b^2<2p\), hence \(a^2+b^2=p\).

Exercise 5.1(Dirichlet.) Let \(\alpha\) be real and \(Q>1\) an integer. Use the linear forms theorem to find integers \(p,q\) with \(1\le q\le Q\) and \(|q\alpha-p|\le1/Q\).

Show solution
Take \(L_1(p,q)=q\alpha-p\), \(L_2(p,q)=q\), with \(\Delta=\det\begin{pmatrix}-1&\alpha\\0&1\end{pmatrix}=-1\), and \(c_1=1/Q\), \(c_2=Q\). Then \(c_1c_2=1=|\Delta|\), so there is \((p,q)\ne0\) with \(|q\alpha-p|\le1/Q\) and \(|q|\le Q\). If \(q=0\) then \(|p|\le1/Q<1\) forces \(p=0\), impossible. Replacing \((p,q)\) by \((-p,-q)\) if needed gives \(1\le q\le Q\).

Exercise 5.2(Lagrange.) Let \(p\) be an odd prime and choose \(a,b\) with \(a^2+b^2+1\equiv0\pmod p\). Let \(\Lambda=\{x\in\mathbb Z^4: x_3\equiv ax_1+bx_2,\ x_4\equiv bx_1-ax_2 \pmod p\}\). Show that \(p\) is a sum of four squares.

Show solution
\(\Lambda\) has index \(p^2\), so \(\det\Lambda=p^2\). For \(x\in\Lambda\), \(x_3^2+x_4^2\equiv(a^2+b^2)(x_1^2+x_2^2)\equiv-(x_1^2+x_2^2)\), so \(|x|^2\equiv0\pmod p\). The open ball \(|x|^2<2p\) in \(\mathbb R^4\) has volume \(\frac{\pi^2}{2}(2p)^2=2\pi^2p^2>16p^2=2^4\det\Lambda\). So some non-zero \(x\in\Lambda\) has \(0<|x|^2<2p\) and \(p\mid|x|^2\), hence \(|x|^2=p\). Products of sums of four squares are sums of four squares (Euler’s identity), and \(2=1+1+0+0\), so every positive integer is a sum of four squares.

Exercise 5.3Show that the constant \(2^n\) cannot be lowered, and that convexity cannot be dropped: find a symmetric set of arbitrarily large area in \(\mathbb R^2\) containing no non-zero point of \(\mathbb Z^2\).

Show solution
The open cube \((-1,1)^n\) is convex and symmetric, has volume exactly \(2^n=2^n\det\mathbb Z^n\), and contains only the lattice point 0. For the second part take the disk \(\{x^2+y^2<R^2\}\) with every non-zero lattice point removed. It is symmetric, has area \(\pi R^2\), and contains no non-zero lattice point. It fails to be convex: \((1,0)\) is the midpoint of \((\tfrac12,0)\) and \((\tfrac32,0)\), which both lie in the set.
Lesson 06

Geometry of numbers in number fields

For the general reader. In a number field, numbers built from roots of polynomials, factorization can fail to be unique, and the class number measures how badly. Minkowski placed the integers of such a field as a lattice in ordinary space. His convex body theorem then shows that the class number is finite and computable, and that every number field other than the rationals has primes that ramify.

Goals
  • Embed the ring of integers as a lattice and compute its covolume.
  • Derive the Minkowski bound and the finiteness of the class group.
  • Prove that \(|d_K|>1\) for every number field \(K\ne\mathbb Q\).

The Minkowski embedding

Let \(K\) be a number field of degree \(n\) with \(r_1\) real embeddings and \(r_2\) pairs of complex embeddings, so \(n=r_1+2r_2\). The map \(j:K\to\mathbb R^{r_1}\times\mathbb C^{r_2}\cong\mathbb R^n\) sends \(\alpha\) to its real embeddings and one embedding from each complex pair. The image of the ring of integers \(\mathcal O_K\) is a lattice with

\[ \det j(\mathcal O_K)=2^{-r_2}\sqrt{|d_K|}, \qquad \det j(\mathfrak a)=2^{-r_2}\sqrt{|d_K|}\,N(\mathfrak a) \]

for a non-zero ideal \(\mathfrak a\), where \(d_K\) is the discriminant and \(N(\mathfrak a)=|\mathcal O_K/\mathfrak a|\).

Theorem (Minkowski bound)

Every ideal class of \(K\) contains an integral ideal \(\mathfrak b\) with

\[ N(\mathfrak b)\le M_K=\frac{n!}{n^n}\Big(\frac4\pi\Big)^{r_2}\sqrt{|d_K|}. \]

Consequently the class group is finite, and it is generated by the classes of prime ideals of norm at most \(M_K\).

Proof sketch

Apply the compact convex body theorem to the lattice \(j(\mathfrak a)\) and the body \(K_t=\{\sum_{\text{real}}|x_i|+2\sum_{\text{complex}}|z_k|\le t\}\), whose volume is \(2^{r_1}(\pi/2)^{r_2}t^n/n!\). Choosing \(t\) so this equals \(2^n\det j(\mathfrak a)\) produces a non-zero \(\alpha\in\mathfrak a\) whose embeddings satisfy the bound. The inequality of arithmetic and geometric means gives \(|N(\alpha)|\le(t/n)^n\), that is, \(|N(\alpha)|\le M_K\,N(\mathfrak a)\). Then \(\mathfrak b=\alpha\mathfrak a^{-1}\) is integral, lies in the class of \(\mathfrak a^{-1}\), and has norm at most \(M_K\). Since \(\mathfrak a\) was arbitrary, every class is reached.

Theorem (Minkowski, 1891)

If \(K\ne\mathbb Q\), then \(|d_K|>1\). More precisely, \(|d_K|\ge\big(\tfrac\pi4\big)^{n}\big(\tfrac{n^n}{n!}\big)^2\), and the right side grows exponentially in \(n\).

Since \(N(\mathfrak b)\ge1\), the bound gives \(\sqrt{|d_K|}\ge\frac{n^n}{n!}(\pi/4)^{r_2}\ge\frac{n^n}{n!}(\pi/4)^{n/2}\). For \(n=2\) the right side squared is \(\pi^2/4>1\), and it increases with \(n\). By Dedekind’s theorem a prime ramifies in \(K\) exactly when it divides \(d_K\), so every proper extension of \(\mathbb Q\) is ramified at some prime. Combined with Charles Hermite’s theorem, the bound also shows there are only finitely many number fields of bounded discriminant, the Hermite–Minkowski theorem.

Exercise 6.1Compute the class number of \(K=\mathbb Q(\sqrt{-5})\), with \(d_K=-20\).

Show solution
\(n=2\), \(r_2=1\): \(M_K=\frac{2}{4}\cdot\frac4\pi\sqrt{20}=\frac{2\sqrt{20}}{\pi}\approx2.85\). So only primes of norm 2 matter. The prime 2 ramifies: \((2)=\mathfrak p^2\) with \(\mathfrak p=(2,1+\sqrt{-5})\). If \(\mathfrak p=(\alpha)\) then \(N(\alpha)=a^2+5b^2=2\), impossible. So \(\mathfrak p\) is non-principal and \(\mathfrak p^2\) is principal; the class group has order 2.

Exercise 6.2Show that \(\mathbb Z[\sqrt2]\) is a principal ideal domain.

Show solution
\(d_K=8\), \(r_2=0\): \(M_K=\frac{2}{4}\sqrt8=\sqrt2\approx1.41\). Every class contains an integral ideal of norm 1, which is \(\mathcal O_K\) itself. So the class number is 1.

Exercise 6.3Show that every cubic field has \(|d_K|\ge13\) using the bound for \(n=3\). (The true minimum is 23.)

Show solution
For \(n=3\), \(r_2\in\{0,1\}\). With \(r_2=1\): \(\sqrt{|d_K|}\ge\frac{27}{6}\cdot\frac\pi4\approx3.53\), so \(|d_K|\ge12.5\), hence \(\ge13\). With \(r_2=0\): \(\sqrt{|d_K|}\ge4.5\), so \(|d_K|\ge20.25\). Either way \(|d_K|\ge13\). The field generated by a root of \(x^3-x-1\) has \(d_K=-23\), the smallest possible.
Lesson 07

Minima, reduction, packing, continued fractions

For the general reader. How tightly can identical balls be packed in a regular grid? How do you pick the “best” basis of a lattice? Minkowski answered the second question completely and gave lasting bounds for the first. Along the way he invented a strange function that turns the continued fraction of a number into its binary expansion.

Goals
  • State the second theorem on successive minima.
  • Relate lattice packings to minima of quadratic forms; compute the hexagonal density.
  • Meet Minkowski reduction, the Minkowski–Hlawka theorem and the question-mark function.

Successive minima

Let \(K\) be a compact convex symmetric body with non-empty interior and \(\Lambda\) a lattice. The \(i\)-th successive minimum \(\lambda_i\) is the smallest \(\lambda\) such that \(\lambda K\) contains \(i\) linearly independent lattice vectors. So \(\lambda_1\le\cdots\le\lambda_n\), and the convex body theorem says \(\lambda_1^n\operatorname{vol}(K)\le2^n\det\Lambda\).

Second theorem of Minkowski (1896) \[ \frac{2^n}{n!}\det\Lambda\;\le\;\lambda_1\lambda_2\cdots\lambda_n\operatorname{vol}(K)\;\le\;2^n\det\Lambda. \]

The lower bound is easy: the cross-polytope spanned by \(\pm v_i/\lambda_i\), for independent \(v_i\) realizing the minima, lies in \(K\) and has volume \(\frac{2^n}{n!}|\det(v_i)|/\prod\lambda_i\ge\frac{2^n}{n!}\det\Lambda/\prod\lambda_i\). The upper bound is much harder; Minkowski’s proof was long, and shorter ones were found only decades later.

Packing and Hermite’s constant

Balls of radius \(r=\lambda_1/2\) (with \(K\) the unit ball) centred at the points of \(\Lambda\) do not overlap. The packing density is

\[ \Delta(\Lambda)=\frac{\operatorname{vol}(B_n)\,(\lambda_1/2)^n}{\det\Lambda}. \]

In the language of forms, Hermite’s constant \(\gamma_n\) is the maximum over lattices of \(\lambda_1^2/(\det\Lambda)^{2/n}\), and maximizing density is the same problem. The convex body theorem gives \(\gamma_n\le4\operatorname{vol}(B_n)^{-2/n}\), roughly linear in \(n\). Minkowski also connected the densest lattice packing of a convex body with the minimum of the associated distance function, opening a line of work continued to the present.

Minkowski–Hlawka theorem (stated by Minkowski; proved by Edmund Hlawka, 1943)

For every \(n\ge2\) there exist lattices in \(\mathbb R^n\) whose ball packings have density at least \(\zeta(n)/2^{n-1}\).

The proof averages over all lattices of covolume 1: the average number of non-zero lattice points in a set of volume \(V\) is \(V\), so some lattice does no worse. No explicit family of lattices is known that beats this bound by more than a polynomial factor in high dimension.

Reduction

A basis \(b_1,\dots,b_n\) of \(\Lambda\) is Minkowski reduced if, for each \(k\), \(b_k\) is a shortest lattice vector that can be extended to a basis together with \(b_1,\dots,b_{k-1}\). In a 1905 paper Minkowski showed that the reduced positive definite forms fill a convex polyhedral cone defined by finitely many inequalities, a fundamental domain for \(\mathrm{GL}_n(\mathbb Z)\) acting on positive definite forms. He used its volume to obtain asymptotics for class numbers of forms. Reduction theory later passed to arithmetic groups through Siegel, Armand Borel and Harish-Chandra; the LLL algorithm of 1982 is a computable weakening of Minkowski reduction.

The question-mark function

In his 1904 Heidelberg lecture Minkowski defined, for \(x=[a_0;a_1,a_2,\dots]\) in continued fraction form,

\[ ?(x)=a_0+2\sum_{k\ge1}\frac{(-1)^{k+1}}{2^{a_1+a_2+\cdots+a_k}}. \]

It is a strictly increasing homeomorphism of \([0,1]\), maps rationals to dyadic rationals and quadratic irrationals to rationals, and has derivative zero almost everywhere. Minkowski introduced it to illustrate an analogue of Lagrange’s theorem that quadratic irrationals have periodic continued fractions.

Exercise 7.1Show that the hexagonal lattice, with basis \((1,0)\) and \((\tfrac12,\tfrac{\sqrt3}2)\), has packing density \(\pi/(2\sqrt3)\approx0.9069\), and compute \(\gamma_2\).

Show solution
\(\lambda_1=1\) and \(\det\Lambda=\sqrt3/2\). Disks of radius \(\tfrac12\) give density \(\pi/4\big/(\sqrt3/2)=\pi/(2\sqrt3)\). Then \(\lambda_1^2/\det\Lambda=2/\sqrt3\), and this is the maximum (Lagrange, Gauss), so \(\gamma_2=2/\sqrt3\).

Exercise 7.2Compute \(?(\tfrac25)\) and \(?\big(\tfrac{\sqrt5-1}{2}\big)\).

Show solution
\(\tfrac25=[0;2,2]\), so \(?=2(2^{-2}-2^{-4})=\tfrac38\). And \(\tfrac{\sqrt5-1}2=[0;1,1,1,\dots]\), so \(?=2\sum_{k\ge1}(-1)^{k+1}2^{-k}=2\cdot\frac{1/2}{1+1/2}=\tfrac23\), a rational value for a quadratic irrational.

Exercise 7.3Check the second theorem for \(\Lambda=\mathbb Z^2\) and \(K\) the unit square \([-1,1]^2\), and for \(K\) the diamond \(|x|+|y|\le1\).

Show solution
Square: \(\lambda_1=\lambda_2=1\), \(\operatorname{vol}=4\), product \(4=2^2\det\Lambda\), the upper bound. Diamond: \(\lambda_1=\lambda_2=1\), \(\operatorname{vol}=2\), product \(2=\frac{2^2}{2!}\det\Lambda\), the lower bound. Both bounds are sharp.
Lesson 08

Convex bodies and mixed volumes

For the general reader. To use convex shapes in number theory, Minkowski needed a theory of the shapes themselves. He created one. He added shapes together, measured how volume grows, and showed among other things that of all shapes with a given area the circle has the shortest boundary. Modern convex geometry starts with this work.

Goals
  • Use Minkowski sums, support functions and norms from convex bodies.
  • State the Brunn–Minkowski inequality and derive the isoperimetric inequality.
  • State Minkowski’s theorem on polytopes with prescribed facets.

Sums and gauges

The Minkowski sum of sets is \(A+B=\{a+b: a\in A, b\in B\}\). A convex body \(K\) is described by its support function \(h_K(u)=\max_{x\in K}\langle x,u\rangle\), and \(h_{A+B}=h_A+h_B\). A symmetric convex body with the origin inside defines a gauge \(\|x\|_K=\min\{\lambda\ge0: x\in\lambda K\}\), a norm whose unit ball is \(K\). Minkowski introduced such general distance functions, anticipating normed spaces; the triangle inequality for \(\ell^p\) norms is still called Minkowski’s inequality.

Mixed volumes

For convex bodies \(K_1,\dots,K_m\) and \(t_i\ge0\), Minkowski showed that \(\operatorname{vol}(t_1K_1+\cdots+t_mK_m)\) is a homogeneous polynomial of degree \(n\) in the \(t_i\); its coefficients are the mixed volumes \(V(K_{i_1},\dots,K_{i_n})\). In the plane, for the unit disk \(B\),

\[ \operatorname{area}(K+tB)=\operatorname{area}(K)+t\,\operatorname{perim}(K)+\pi t^2 \qquad\text{(Steiner’s formula)}, \]

so the mixed area \(V(K,B)\) equals half the perimeter.

Brunn–Minkowski inequality

For convex bodies \(A,B\subset\mathbb R^n\),

\[ \operatorname{vol}(A+B)^{1/n}\ge\operatorname{vol}(A)^{1/n}+\operatorname{vol}(B)^{1/n}, \]

with equality (for bodies with interior) if and only if \(A\) and \(B\) are homothetic. Hermann Brunn proved the inequality in 1887; Minkowski gave a rigorous proof and settled the equality case.

Isoperimetric inequality. In the plane, put \(A=K\) and \(B=tB_1\): \(\operatorname{area}(K+tB_1)\ge(\sqrt{\operatorname{area}K}+t\sqrt\pi)^2\). Compare the coefficients of \(t\) with Steiner’s formula as \(t\to0\): \(\operatorname{perim}(K)\ge2\sqrt{\pi\operatorname{area}K}\), that is, \(L^2\ge4\pi A\), with equality only for disks.

Minkowski’s theorem on polytopes (1897)

Let \(u_1,\dots,u_m\) be distinct unit vectors spanning \(\mathbb R^n\) and \(a_1,\dots,a_m>0\) with \(\sum_i a_iu_i=0\). Then there is a convex polytope whose facets have outer normals \(u_i\) and \((n-1)\)-dimensional areas \(a_i\), and it is unique up to translation.

The condition \(\sum a_iu_i=0\) is necessary: it is the divergence theorem applied to a constant vector field. Minkowski extended the result to smooth convex surfaces with prescribed Gauss curvature as a function of the normal, the Minkowski problem, whose regularity theory occupied geometric analysis for much of the twentieth century. He also studied bodies of constant width.

Exercise 8.1Check the condition \(\sum a_iu_i=0\) for the triangle with vertices \((0,0),(1,0),(0,1)\).

Show solution
Edges: bottom, length 1, normal \((0,-1)\); left, length 1, normal \((-1,0)\); hypotenuse, length \(\sqrt2\), normal \((1,1)/\sqrt2\). Sum: \((0,-1)+(-1,0)+(1,1)=0\).

Exercise 8.2Let \(K\) be the square \([0,1]^2\). Compute \(\operatorname{area}(K+tB_1)\) directly and check Steiner’s formula and the isoperimetric inequality.

Show solution
\(K+tB_1\) is the square plus four \(1\times t\) rectangles plus four quarter disks: \(1+4t+\pi t^2\). The perimeter is 4, as Steiner predicts. And \(L^2=16\ge4\pi\cdot1\approx12.57\).

Exercise 8.3Show that the Minkowski sum of a convex body of constant width \(w\) with its reflection \(-K\) is a disk of radius \(w\). Deduce Barbier’s theorem: the perimeter of \(K\) is \(\pi w\).

Show solution
Constant width means \(h_K(u)+h_K(-u)=w\) for all \(u\). Then \(h_{K+(-K)}(u)=h_K(u)+h_{-K}(u)=h_K(u)+h_K(-u)=w\), the support function of the disk of radius \(w\). Perimeter is additive under Minkowski sums in the plane (it is twice the mixed area with the unit disk, which is linear), and \(-K\) has the same perimeter as \(K\). So \(2\operatorname{perim}(K)=2\pi w\).
Lesson 09

Space and time become spacetime

For the general reader. Einstein’s 1905 theory said that moving clocks run slow and moving rods shrink. Minkowski saw a simpler way to say it. There is one four-dimensional world, and different observers slice it into “space” and “time” in different ways, much as different people looking at a room choose different directions as “forward”. What all observers agree on is a kind of distance in this world, with a minus sign where Euclid had a plus.

Goals
  • Define the Minkowski interval and the Lorentz group.
  • Read Lorentz boosts as hyperbolic rotations.
  • Use the light cone, world lines and proper time; resolve the twin paradox.

The interval

Label an event by \(x=(x^0,x^1,x^2,x^3)=(ct,x,y,z)\). Minkowski singled out the quadratic form

\[ s^2=\eta_{\mu\nu}x^\mu x^\nu=(x^0)^2-(x^1)^2-(x^2)^2-(x^3)^2,\qquad \eta=\operatorname{diag}(1,-1,-1,-1). \]

(Minkowski himself wrote \(x_4=ict\) to make the form look Euclidean; the real form with signature is now standard.) A vector is timelike if \(s^2>0\), lightlike if \(s^2=0\), and spacelike if \(s^2<0\). The lightlike vectors form the light cone. Minkowski called points of spacetime world points and the history of a particle its world line, and he named the whole structure the world.

The postulate, in Minkowski’s form

The laws of physics are invariant under the Lorentz group \(\mathrm O(1,3)=\{\Lambda\in\mathrm{GL}_4(\mathbb R): \Lambda^{\mathsf T}\eta\Lambda=\eta\}\), together with translations: the Poincaré group. Every linear map preserving \(s^2\) is in \(\mathrm O(1,3)\).

Boosts are hyperbolic rotations

In the \((x^0,x^1)\)-plane a boost with velocity \(v=c\tanh\phi\) is

\[ \begin{pmatrix}x'^0\\x'^1\end{pmatrix}=\begin{pmatrix}\cosh\phi&-\sinh\phi\\-\sinh\phi&\cosh\phi\end{pmatrix}\begin{pmatrix}x^0\\x^1\end{pmatrix},\qquad \gamma=\cosh\phi=\frac{1}{\sqrt{1-v^2/c^2}}. \]

It preserves \((x^0)^2-(x^1)^2\) because \(\cosh^2\phi-\sinh^2\phi=1\). The rapidity \(\phi\) plays the role of an angle, and boosts in one direction compose by adding rapidities. On a diagram (see the hero figure) the moving time axis \(x'^1=0\) and space axis \(x'^0=0\) tilt toward the light cone by equal amounts, and the unit marks lie on the hyperbolas \(s^2=\pm1\).

Proper time

A clock moving along a timelike world line \(x(t)\) measures the proper time

\[ \tau=\frac1c\int\sqrt{\eta_{\mu\nu}\,dx^\mu dx^\nu}=\int\sqrt{1-\frac{v(t)^2}{c^2}}\,dt. \]

Among timelike curves between two events, the straight one has the greatest proper time: the reverse of the Euclidean triangle inequality. Time dilation, the twin paradox and the relativity of simultaneity all follow from this geometry. Minkowski presented it in Göttingen on 5 November 1907 and to a wide audience in Cologne on 21 September 1908. His opening sentence there announced that space by itself and time by itself were to sink into shadows (“zu Schatten herabsinken”), with only a union of the two preserving independent reality.

Exercise 9.1Show that composing boosts with velocities \(u\) and \(v\) along the same axis gives velocity \(\dfrac{u+v}{1+uv/c^2}\).

Show solution
With \(u=c\tanh\alpha\), \(v=c\tanh\beta\), the composite boost has rapidity \(\alpha+\beta\), so velocity \(c\tanh(\alpha+\beta)=c\dfrac{\tanh\alpha+\tanh\beta}{1+\tanh\alpha\tanh\beta}=\dfrac{u+v}{1+uv/c^2}\).

Exercise 9.2A twin travels at \(v=0.8c\) to a star 8 light-years away and returns at the same speed. How much does each twin age?

Show solution
In the Earth frame the trip takes \(2\cdot8/0.8=20\) years. The traveller’s proper time is \(20\sqrt{1-0.64}=20\cdot0.6=12\) years. The Earth twin ages 20 years. The paths are not symmetric: the traveller’s world line is bent at the turnaround, and the straight world line maximises proper time.

Exercise 9.3Show that if \(x\) is timelike and future-pointing, every event \(y\) with \((y-x)\) spacelike is simultaneous with \(x\) in some inertial frame, and no frame reverses the time order of two timelike-separated events.

Show solution
If \(\Delta=y-x\) is spacelike, rotate so that \(\Delta=(\Delta^0,\Delta^1,0,0)\) with \(|\Delta^0|<|\Delta^1|\). The boost with \(\tanh\phi=\Delta^0/\Delta^1\) gives \(\Delta'^0=\Delta^0\cosh\phi-\Delta^1\sinh\phi=0\). If \(\Delta\) is timelike with \(\Delta^0>0\), then \(\Delta'^0=\cosh\phi\,(\Delta^0-\tanh\phi\,\Delta^1)>0\) because \(|\tanh\phi|<1\) and \(|\Delta^1|<\Delta^0\). Causal order is invariant; simultaneity is not.
Lesson 10

Four-vectors and electrodynamics

For the general reader. In Minkowski’s 1908 paper on electrodynamics, the electric and magnetic fields stop being two separate things. They are two faces of one object in four dimensions, and Maxwell’s equations shrink to two short lines. The same geometry turns energy and momentum into one four-dimensional arrow whose length is the mass.

Goals
  • Build four-velocity and four-momentum and derive \(E^2=p^2c^2+m^2c^4\).
  • Write Maxwell’s equations with the field tensor \(F^{\mu\nu}\).
  • Find the Lorentz invariants of the field.

Kinematics

For a world line parametrized by proper time, the four-velocity is \(u^\mu=dx^\mu/d\tau=\gamma(c,\mathbf v)\), with \(\eta_{\mu\nu}u^\mu u^\nu=c^2\). The four-momentum is \(p^\mu=mu^\mu=(E/c,\mathbf p)\). Then

\[ \eta_{\mu\nu}p^\mu p^\nu=m^2c^2\quad\Longleftrightarrow\quad E^2=\mathbf p^2c^2+m^2c^4, \]

and at rest \(E=mc^2\). Minkowski’s 1908 paper gave the four-dimensional form of the equation of motion of a point mass, \(m\,du^\mu/d\tau=K^\mu\), with the four-force \(K^\mu\) orthogonal to \(u^\mu\).

The field tensor

In units with \(c=1\) (Heaviside–Lorentz), let \(A^\mu=(\varphi,\mathbf A)\) and \(F^{\mu\nu}=\partial^\mu A^\nu-\partial^\nu A^\mu\). Then \(F^{i0}=E^i\) and \(F^{ij}=-\varepsilon^{ijk}B^k\). Minkowski called such an antisymmetric object a “space-time vector of the second kind”, now a 2-form.

Maxwell’s equations (Minkowski, 1908) \[ \partial_\mu F^{\mu\nu}=J^\nu,\qquad \partial_\lambda F_{\mu\nu}+\partial_\mu F_{\nu\lambda}+\partial_\nu F_{\lambda\mu}=0, \]

with \(J^\mu=(\rho,\mathbf J)\). The first equation contains Gauss’s law and the Ampère–Maxwell law; the second, Faraday’s law and \(\nabla\cdot\mathbf B=0\). The Lorentz force is \(dp^\mu/d\tau=qF^{\mu\nu}u_\nu\).

Check one component: for \(\nu=0\), \(\partial_iF^{i0}=\nabla\cdot\mathbf E=\rho\). For the force with \(\mu=i\): \(F^{i0}u_0=\gamma E^i\) and \(F^{ij}u_j=\gamma(\mathbf v\times\mathbf B)^i\), so \(d\mathbf p/d\tau=q\gamma(\mathbf E+\mathbf v\times\mathbf B)\).

Matter

The larger part of Minkowski’s paper treated fields in moving media, with \(\mathbf D,\mathbf H\) joined into a second tensor and constitutive relations written covariantly. His expression for the energy–momentum tensor in media differs from the one Max Abraham proposed in 1909. The resulting Abraham–Minkowski debate over the momentum of light in a medium continued for a century; the modern view is that both are correct once the momentum of the medium is accounted for.

Exercise 10.1Show that \(F_{\mu\nu}F^{\mu\nu}=2(\mathbf B^2-\mathbf E^2)\), and conclude that \(\mathbf E^2-\mathbf B^2\) is the same in every inertial frame.

Show solution
The mixed components contribute \(2F_{0i}F^{0i}\). Lowering one time index and one space index gives \(F_{0i}=-F^{0i}\), so \(2F_{0i}F^{0i}=-2\sum(F^{0i})^2=-2\mathbf E^2\). Purely spatial components keep their sign: \(\sum_{i,j}(F^{ij})^2=2\mathbf B^2\). Total \(2(\mathbf B^2-\mathbf E^2)\), a scalar, hence invariant.

Exercise 10.2A photon with energy \(E\) hits an electron at rest. Use four-momentum conservation to derive the Compton formula for the scattered energy \(E'\) at angle \(\theta\).

Show solution
Write \(k,k'\) for photon four-momenta, \(P,P'\) for the electron. From \(P'=k+P-k'\), square: \(m^2=m^2+2P\cdot(k-k')-2k\cdot k'\) (with \(c=1\), \(k^2=k'^2=0\)). So \(m(E-E')=EE'(1-\cos\theta)\), giving \(\dfrac1{E'}-\dfrac1E=\dfrac{1-\cos\theta}{m}\).

Exercise 10.3Show that \(\mathbf E\cdot\mathbf B\) is Lorentz invariant, and deduce that a pure magnetic field in one frame cannot be a pure electric field in another.

Show solution
\(\varepsilon_{\mu\nu\lambda\sigma}F^{\mu\nu}F^{\lambda\sigma}\) is a scalar (the Levi-Civita symbol is invariant under \(\mathrm{SO}^+(1,3)\)), and it equals a non-zero multiple of \(\mathbf E\cdot\mathbf B\). For the second claim use Exercise 10.1: a pure magnetic field has \(\mathbf E^2-\mathbf B^2<0\), a pure electric field has it \(>0\), and the invariant cannot change sign.
Part III · Life and legacy
Lesson 11

Göttingen, 1902–1909

In 1902 Hilbert persuaded the Prussian ministry to create a third chair of mathematics at Göttingen, beside Felix Klein’s and his own, and Minkowski took it. For six years the two friends led the most active mathematics department in the world. They taught joint seminars, walked daily, and argued about everything. Minkowski’s doctoral students there included Constantin Carathéodory (1904), Paul Wernicke (1904) and Elijah Swift (1907); Louis Kollros (Zürich, 1905) and Dénes Kőnig (1907) also count him as advisor.

At the 1904 International Congress in Heidelberg he lectured on the geometry of numbers, and in 1907 he published Diophantische Approximationen, an introduction to number theory through his geometric methods. His attention, however, was moving toward physics. In the summer of 1905 he and Hilbert ran a seminar on the electron theory of Hendrik Lorentz, Henri Poincaré and others. After Einstein’s paper of 1905 he studied the new kinematics and saw its geometric content.

Three texts on relativity

  • 5 November 1907: Das Relativitätsprinzip, a lecture to the Göttingen Mathematical Society, published posthumously in 1915 in a version edited by Arnold Sommerfeld.
  • 21 December 1907: Die Grundgleichungen für die elektromagnetischen Vorgänge in bewegten Körpern, presented to the Göttingen Society of Sciences and printed in its Nachrichten in 1908 (Lesson 10).
  • 21 September 1908: Raum und Zeit, the Cologne lecture, printed in 1909 in the Physikalische Zeitschrift and the Jahresbericht of the German Mathematical Society.

Minkowski presented relativity as the discovery of a new invariant geometry. He regarded Einstein’s 1905 paper as an important step but felt its mathematical structure had not been fully seen. Einstein at first thought the four-dimensional formalism added learned complication without new physics. Sommerfeld reported that Einstein joked he no longer understood his own theory once the mathematicians had taken it up. After 1912, working on gravitation, Einstein adopted Minkowski’s geometry fully; general relativity is the theory in which Minkowski’s flat world becomes curved.

Max Born, who had heard the Cologne lecture, joined Minkowski as a collaborator in December 1908 to work on relativistic electrodynamics.

DiscussionPoincaré had noticed in 1905–1906 that the Lorentz transformations preserve \(x^2+y^2+z^2-c^2t^2\) and used an imaginary fourth coordinate. Why is the four-dimensional view usually credited to Minkowski? Consider what each man did with the observation.

Lesson 12

Sudden death and long legacy

Shortly after Christmas 1908 Minkowski fell ill with appendicitis. Peritonitis set in, an operation came too late, and he died in Göttingen on 12 January 1909, aged 44. Hilbert, who lost his closest friend, gave the memorial address and edited the Gesammelte Abhandlungen (1911), with Andreas Speiser and Hermann Weyl. Born and Speiser sorted his papers, and Born completed his unfinished work on the electron. The second part of Geometrie der Zahlen appeared in 1910. Minkowski was buried in Göttingen. In 1932 his remains were moved to the Heerstraße cemetery in Berlin, beside those of his brother Oskar.

Legacy

  • Physics: Minkowski space is the arena of special relativity and quantum field theory, and the local model of every spacetime in general relativity. Words he coined, world line and world point, remain in use.
  • Number theory: the geometry of numbers underlies the finiteness theorems of algebraic number theory, Diophantine approximation, the subspace theorem, reduction theory of arithmetic groups and Arakelov geometry.
  • Convex geometry and analysis: mixed volumes, the Brunn–Minkowski inequality and the Minkowski problem are central in convex and geometric analysis; Minkowski sums and gauges are basic tools in optimization.
  • Computation and cryptography: lattice reduction and the hardness of short-vector problems, both descended from his questions, underlie modern lattice-based cryptography.
  • Family: his nephew Rudolph Minkowski, son of Oskar, became an astronomer known for work on supernovae and the Palomar Sky Survey.
  • Honours: the lunar crater Minkowski and asteroid 12493 Minkowski bear his name.

Final projectWrite a two-page account, for a strong undergraduate, of how one idea (the quadratic form \(x^{\mathsf T}Ax\)) runs through Minkowski’s work: as an ellipsoid in the geometry of numbers, as the object of reduction theory, and as the indefinite form of spacetime. Include one worked example from each setting.

Reference

Connections

People linked to Hermann Minkowski across this collection. A name without a link has no page here yet. See Hermann Minkowski in the network of all 337 lives →

Teachers and advisors

  • Ferdinand von Lindemann 1885

Students

  • Albert Einstein 1896-1900
  • Constantin Carathéodory 1904
  • Dénes Kőnig 1907
  • Elijah Swift 1907
  • Louis Kollros 1905
  • Paul Wernicke 1904

Influenced by

Influenced

Colleagues and collaborators

Rivals

  • Henry John Stephen Smith 1883

Friends

Family

  • Oskar Minkowski
  • Rudolph Minkowski

Also mentioned in this life

Fields

On CoursesHub

Reference

Sources and further reading

Biography

  1. J. J. O’Connor and E. F. Robertson, Hermann Minkowski, MacTutor History of Mathematics.
  2. Hermann Minkowski, Wikipedia.
  3. Minkowski, Hermann, Neue Deutsche Biographie 17 (1994).
  4. Minkowski, Hermann, Dictionary of Scientific Biography.
  5. D. Hilbert, Hermann Minkowski, Math. Ann. 68 (1910), 445–471.
  6. H. Minkowski, Briefe an David Hilbert, ed. L. Rüdenberg and H. Zassenhaus, Springer, 1973.
  7. D. Rowe, A look back at Hermann Minkowski’s Cologne lecture “Raum und Zeit”, Math. Intelligencer 31 (2009), 27–39.
  8. J. Schwermer, Räumliche Anschauung und Minima positiv definiter quadratischer Formen, Jahresber. DMV 93 (1991), 49–105.

Mathematics and physics

  1. H. Minkowski, Geometrie der Zahlen, Teubner, 1896 and 1910.
  2. H. Minkowski, Diophantische Approximationen, Teubner, 1907.
  3. H. Minkowski, Die Grundgleichungen für die elektromagnetischen Vorgänge in bewegten Körpern, Nachr. Ges. Wiss. Göttingen (1908), 53–111.
  4. H. Minkowski, Raum und Zeit, Physikalische Zeitschrift 10 (1909), 104–111; Jahresber. DMV 18 (1909), 75–88. English translation on Wikisource.
  5. H. Minkowski, Gesammelte Abhandlungen, ed. D. Hilbert, 2 vols., Teubner, 1911.
  6. J. W. S. Cassels, An Introduction to the Geometry of Numbers, Springer, 1959.
  7. J.-P. Serre, A Course in Arithmetic, Springer, 1973 (Hasse–Minkowski theorem).
  8. J. Neukirch, Algebraic Number Theory, Springer, 1999, ch. I (Minkowski theory).
  9. R. Schneider, Convex Bodies: The Brunn–Minkowski Theory, 2nd ed., Cambridge, 2014.
  10. R. J. Gardner, The Brunn–Minkowski inequality, Bull. AMS 39 (2002), 355–405.
  11. S. Walter, Minkowski, mathematicians, and the mathematical theory of relativity, in The Expanding Worlds of General Relativity, Birkhäuser, 1999.
  12. G. Weinstein, Max Born, Albert Einstein and Hermann Minkowski’s space-time formalism of special relativity, arXiv:1210.6929.