The Golden Age of Modern Physics lasted from the 1880s to 1945, with a paradigm shift in physics, with the theory of relativity and quantum mechanics, leading up to the first atomic bomb.

Many of the celebrity scientists won the Nobel Prize for physics. The era represented a transition of research from individual scientists to the "big science" from World War II and onwards.

See nuclear tourism for nuclear sites past World War II.

Understand

By the late 19th century, the theories of mechanics and electromagnetism were seen as completed. As in many other times in history of physics, there were still unresolved problems and paradoxes; such as the nature of gravity, heat, as well as light and other electro-magnetic radiation.

Light and other electro-magnetic waves were believed to be dependent on a material for propagation, in similarity to mechanical waves such as sound. Physicists believed that radiation was carried by the aether, an invisible matter supposed to fill the universe. The 1880s Michelson-Morley experiments failed to measure the aether's effect on the speed of light. The theory of relativity rejected the supposedly absolute nature of space and time, allowing for a new model of light and waves.

In the 1890s, radioactivity was discovered by Henri Becquerel and Marie Curie. The theory of relativity and quantum physics were developed in the early 20th century to describe the relationship between space, time, radiation, and elementary particles.

Besides nuclear technology, modern physics got applications in spaceflight, navigation and electronics, among other fields.

Destinations

• 1 Marie Curie Museum (Warsaw, Poland). History of radioactivity.  
• 2 Einstein Tower (Potsdam, Germany).  
• 1 Einsteinhaus, Kramgasse 49 (Berne, Switzerland), ☏ +41 31 312 00 91, webmaster@einstein-bern.ch. Einstein rented this flat 1903-05 with his first wife Mileva, during his years working at the Swiss patent office. His special and general theories of relativity were born in this flat, which now displays photos and original documents from his life, work, and speeches.  
• 3 Solvay Conference (Brussels). These were a series of conferences, named for their sponsor, focusing on unsolved problems in physics and chemistry. From the first conference in 1911, they were an important part of the new physics. The fifth conference in 1927 was particularly important; Heisenberg said it brought "the outward completion of the quantum theory". 17 of the 29 participants, shown in the banner photo for this article, won Nobel Prizes.  
• 4 Princeton (New Jersey, United States). Einstein and others worked at the Institute for Advanced Study.  
• 5 First nuclear reactor (Chicago Pile-1). A group led by Enrico Fermi built the first working nuclear reactor in a tennis court at the University of Chicago in 1942. This was one step in the Manhattan project which produced the Bomb a few years later.  

• 6 Los Alamos (Manhattan Project) (New Mexico, United States). During World war II this isolated site was a top secret lab where the atomic bomb was developed. It is no longer secret but still has a large government research lab.  
• 7 Trinity site (New Mexico, United States). the site of the world's first nuclear explosion on 16 July 1945, which started the Atomic age. The ground zero, where the plutonium bomb was detonated from a tower, is marked with a plain stone monument. Careful visitors can spot glassy green pieces in the dirt. It is "Trinitite", sand fused by the enormous heat of the explosion into a crusty surface. Most of Trinitite was cleared away in the years after the test with a small piece of original surface preserved in a shelter.  
• 8 Niels Bohr Institutet, Blegdamsvej 17 (Copenhagen, Denmark). If you are a physicist or just interested in physics, come to the Institute and see the room of Niels Bohr with photos of the staff of the institute when he was the head of it, a model of the famous thought experiment weighing the clock, the archive, the photos of all the famous people who were developing the quantum theory during the so-called "golden age of physics, when even small people could do big things" and also the modern part of the institute. 
• 9 Boltzmann's grave, Zentralfriedhof (Vienna, Austria). The Boltzmann equation was formulated by Ludwig Boltzmann between 1872 to 1875. It relates the entropy S of an ideal gas to the quantity W, which is the number of microstates corresponding to a given macrostate. In the ideal gas limit it exactly corresponds to the proper thermodynamic entropy. 
• 10 Schwinger's grave (Cambridge (Massachusetts), USA). The first order correction to the fine structure constant (alpha) is engraved on Julian Schwinger's headstone at the Mt Auburn Cemetery. 
• 11 Schrödinger's grave (Alpbach, Austria). In 1925, Erwin Schrödinger described the partial differential equation which describes a quantum particle, later known as the Schrödinger equation. It is inscribed above his name on his grave site. 
• 12 Nobel Prize Museum (Nobelmuseet), Stortorget. The Nobel Prize Museum has lots of material on the Nobel Prize, including videotaped speeches by laureates. Since 1914, the upper floor is used by the 18 members of the Swedish Academy, since 1901 the jury for the Nobel Prize for literature.  
• 13 Haigerloch, Germany (Atomkeller Museum). A site of a former research reactor called Atomkeller (Atomic cellar), which never went critical. The museum tells the story of the Uranverein (Uranium society), a German attempt to develop a nuclear weapon, and shows the Haigerloch nuclear reactor replica.  
• 14 Vemork, Norway. Heavy water production site and location of war-time heavy water sabotage. Heavy water is an important component in certain nuclear applications and was seen as critically necessary for the development of a nuclear bomb during World War II. Despite the German occupation of Norway, Norwegian underground fighters ultimately managed to keep the heavy water out of the hand of the Nazis, thereby delaying the nuclear program of Nazi Germany which failed.  

See also

• Astronomy
• Mathematics tourism
• Space flight sites for the Space Race which began with World War II