The 20th century was a period of significant advancement in physics, and German physicists played a crucial role in many developments. Here are some key figures and their contributions: 1. **Max Planck (1858-1947)**: Often considered the father of quantum theory, Planck introduced the concept of quantization of energy. His work on black-body radiation led to Planck's constant and fundamentally changed our understanding of atomic and subatomic processes.

The 20th century was a remarkable period for French physicists, who made significant contributions across various fields of physics. Here are a few notable figures: 1. **Marie Curie (1867-1934)**: Although much of her pioneering work on radioactivity occurred in the late 19th and early 20th centuries, her influence extended well into the 20th century.

The 20th century saw several prominent Finnish physicists who made significant contributions to various fields of physics. Here are a few notable figures: 1. **Hannes Alfvén** (1908-1995) - A pioneer in the field of plasma physics, Alfvén was awarded the Nobel Prize in Physics in 1970 for his work on magnetohydrodynamics and the theory of cosmic plasma. 2. **Leo P.

The 20th century saw the emergence of several notable Estonian physicists who contributed to various fields within physics, especially after Estonia regained independence in 1991. Some key figures include: 1. **Georg Ots**: A prominent physicist who contributed to theoretical physics and participated in research related to condensed matter physics. 2. **Erik J. L. P. Liivamägi**: Known for his work in the fields of atomic physics and quantum mechanics.

The 20th century saw significant contributions from Dutch physicists to various fields of physics. Here are some notable figures and their achievements: 1. **Hendrik Lorentz (1853–1928)** - Lorentz made groundbreaking contributions to the understanding of electromagnetism and is best known for the Lorentz transformations, which are fundamental to Einstein's theory of special relativity. He was awarded the Nobel Prize in Physics in 1902. 2. **Albert A.

The 20th century saw significant contributions from Danish physicists, with Niels Bohr being one of the most prominent figures. 1. **Niels Bohr (1885-1962)**: Bohr was awarded the Nobel Prize in Physics in 1922 for his foundational work in atomic structure and quantum theory, particularly the Bohr model of the atom.

The 20th century was a significant period for Chinese physics, marked by the emergence of several influential physicists who made notable contributions to various fields. Here are some key figures: 1. **Qian Xuesen (Tsien Hsue-shen)** (1911–2009): A prominent aerodynamics and spacecraft design scientist, Qian was instrumental in the development of rocket technology in China.

The 20th century saw many significant contributions from Canadian physicists who advanced the field in various areas, including quantum mechanics, nuclear physics, and condensed matter physics. Here are a few notable Canadian physicists from the 20th century: 1. **Bertram N.

In the 20th century, Bulgaria produced several notable physicists who made significant contributions to various fields within physics. Some of the prominent Bulgarian physicists from that era include: 1. **Angel Kanchev** - Known for his contributions to the fields of nuclear physics and particle physics.

The 20th century was a remarkable period for British physics, marked by significant contributions from numerous physicists who made groundbreaking advancements in various fields. Here are some notable British physicists from that era: 1. **J.J. Thomson (1856-1940)**: Known for discovering the electron in 1897, he was awarded the Nobel Prize in Physics in 1906 for his work on electrical conductivity in gases.

The 20th century was a pivotal period for Brazilian physics, marked by the contributions of several prominent physicists who significantly advanced the field in Brazil and internationally.

The 20th century was a remarkable period for Austrian physics, with several notable physicists making significant contributions to various fields. Here are a few prominent Austrian physicists from that time: 1. **Erwin Schrödinger (1887-1961)**: A key figure in quantum mechanics, Schrödinger is best known for the formulation of the Schrödinger equation, which describes how the quantum state of a physical system changes over time.

The 20th century saw significant contributions from Australian physicists in various fields, including quantum mechanics, nuclear physics, and astrophysics. Here are some notable figures: 1. **William Lawrence Bragg (1890-1971)**: Bragg was a physicist who, along with his father, William Henry Bragg, won the Nobel Prize in Physics in 1915 for their work in X-ray crystallography.

The 20th century saw several influential Argentine physicists who made significant contributions to various fields, including theoretical physics, nuclear physics, and condensed matter physics. Here are a few notable Argentine physicists from that era: 1. **Carlos Chagas** - Although primarily known as a physician, Chagas's work involved significant interdisciplinary approaches, impacting biophysics and public health in Argentina.

The 20th century saw remarkable advancements in physics, largely driven by the work of many influential American physicists. Here are some key figures and their contributions: 1. **Albert Einstein** (1879-1955) - Although German-born, Einstein became a key figure in American physics after moving to the U.S. in 1933. His theories of Special and General Relativity fundamentally changed our understanding of space, time, and gravity.

The 20th century saw the emergence of several notable Algerian physicists who made significant contributions to the field of physics, especially in the context of the broader scientific community. Here are a few notable figures: 1. **Ahmed Zewail** (1946-2016): Although primarily known as an Egyptian-American, Zewail was born in Egypt and had Algerian roots.

The 20th century was a prolific period for mathematics, marked by significant advancements and the contributions of numerous influential mathematicians. Here are some key figures and developments from that era: 1. **David Hilbert**: Known for his work in various fields including algebra, number theory, and mathematical logic, Hilbert is famous for his formulation of Hilbert's problems in 1900, which set the agenda for much of 20th-century mathematics.

In mathematics, "1990s" often refers to the decade that spans from 1990 to 1999. This does not have a specific mathematical meaning, but the 1990s were notable for several developments in various fields of mathematics. During this decade, significant progress was made in areas such as: 1. **Computer Science and Mathematics**: The rise of computational mathematics and numerical methods became more prominent, with advancements in algorithms, complexity theory, and optimization.

In mathematics, "1970s" does not refer to a specific mathematical concept or term. However, it can refer to the decade itself and the developments and contributions in mathematics during that period. The 1970s were notable for several advancements in various fields of mathematics, including: 1. **Computer Science and Algorithms**: The development of algorithms and theories surrounding computational complexity, including the introduction of concepts like NP-completeness by Stephen Cook.

In mathematics, the term "1950s" usually refers to the decade that brought significant developments and progress across various fields of mathematical research and education. During the 1950s: 1. **Set Theory and Logic**: The foundations of set theory, particularly as developed by mathematicians like Paul Cohen and others, were expanded. Cohen's work on the independence of the continuum hypothesis would come later, but the foundational ideas were being explored.