Notices tagged with otd, page 5

Physicist and astronaut Ronald McNair was born #OTD in 1950. He spent about 8 days in space aboard Challenger in 1984 during STS-41-B. McNair was one of the seven crew members who lost their lives in the 1986 Challenger disaster.

Image: NASA

Subrahmanyan Chandrasekhar was born #OTD in 1910. He established an upper limit on the mass of stable white dwarf stars, and made numerous contributions to astrophysics and relativity.

Above the Chandrasekhar Limit – about 1.44 solar masses – stars eventually explode and then collapse into a neutron star or black hole.

Photo: Stephen Lewellyn / AIP

“I just always assumed, despite the fact that the US hadn’t sent any women up there, or people of color, that I was going to go.”

Dr. Mae Jemison (@maejemison) was born #OTD in 1956. Doctor, peace corps volunteer, first Black woman in space, and first astronaut on Star Trek.

Crossing Brougham Bridge in Dublin #OTD in 1843, William Hamilton had a flash of insight. He finally understood how to multiply quaternions after puzzling over the problem for years. He scratched the result into the stone:

i² = j² = k² = ijk = -1

Image: Wikimedia

The most energetic single particle ever detected, a cosmic ray dubbed the "Oh-My-God" particle, was observed by the Fly's Eye Cosmic Ray Detector #OTD in 1991.

Its energy was about 3.2 x 10²⁰ eV ~ 51 J, equivalent to a baseball moving at almost 60 mph.

https://www.quantamagazine.org/the-particle-that-broke-a-cosmic-speed-limit-20150514/

Image: Olena Shmahalo/Quanta Magazine, using images of the Earth from NASA.

Charles Messier discovered the Whirlpool galaxy #OTD in 1773. The designation M51 refers to its entry in the catalog he produced.

Pretty good galaxy.

Credit: NASA/ESA/S. Beckwith (STScI)/HHT (STScI/AURA)

Astronomer Ejnar Hertzsprung was born #OTD in 1873.

The Hertzsprung-Russell diagram plots the luminosity of stars vs their surface temperature. The vertical axis is luminosity, low to high moving upwards. The horizontal axis is temperature, from higher to lower reading left to right.

Emoji H-R diagram!

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Danish physicist Niels Bohr was born #OTD in 1885.

Bohr applied the nascent quantum theory to the structure of the Hydrogen atom, offering an explanation (though not a true mechanism) for an outstanding problem that classical physics could not account for.

Image: Atomic Heritage Foundation

VAR!

In the early morning hours #OTD in 1923, Edwin Hubble took a photo plate of M31 showing a Cepheid variable star.

Using Henrietta Swan Leavitt’s distance-luminosity relationship, Hubble concluded that M31 is located outside the Milky Way.

This observation established that there are other galaxies besides our Milky Way, that our little island is not the whole Universe.

Image: Carnegie Observatories

The Space Age began sixty four years ago, #OTD in 1957, when Sputnik 1 was launched into low Earth orbit. It was the first satellite made by humans.

Image: NSSDC, NASA

Dave Arneson, co-creator of Dungeons & Dragons, was born #OTD in 1947.

Enrico Fermi, one of the foremost physicists of the 20th century, was born #OTD in 1901. While most physicists focus on either experiment or theory, Fermi excelled at both.

Now, estimate how many new physicists will be born today.

Image: New York Public Library

Astronomer and mathematician Pierre-Louis Moreau de Maupertuis, exact date of birth unknown, was born around this time in 1698 and baptized #OTD.

He was among the first to articulate the Principle of Least Action, one of the most beautiful ideas in physics.

Image: Wellcome Trust

If there is one physics formula everyone knows, it's E = mc².

Einstein proposed the famous equivalence between energy and mass in his second special relativity manuscript, which he submitted to Annalen der Physik #OTD in 1905.

https://www.fourmilab.ch/etexts/einstein/E_mc2/www/

Happy 118th birthday to special relativity!

Albert Einstein introduced special relativity in the paper "On The Electrodynamics Of Moving Bodies," published #OTD in 1905 in the journal Annalen der Physik.

Manuscript: https://onlinelibrary.wiley.com/doi/abs/10.1002/andp.19053221004
English Translation: https://www.fourmilab.ch/etexts/einstein/specrel/www/

Every story the Universe tells is a history.

Danish astronomer Ole Rømer was born #OTD in 1644. His observations of Jovian moons confirmed light propagates at finite speed. This profound conceptual shift opened the door for work by Huygens, Fresnel, and Maxwell.

Portrait: Jacob Conring / Wikimedia Commons

Astrophysicist Charlotte Moore Sitterly was born #OTD in 1898.

She compiled extensive data on optical and later UV spectra, and her spectroscopic tables are still in use today.

Image: AIP Emilio Segrè Visual Archives / Michael A. Duncan

Happy 115th birthday, spacetime!

Hermann Minkowski addressed the 80th Assembly of German Natural Scientists and Physicians #OTD in 1908, offering a radical four-dimensional reformulation of Einstein's theory of special relativity.

His opening lines:

The mathematician Paul Erdős had a fantasy that he'd die giving a lecture: he would prove a result, someone would ask about a generalization, he'd reply "I'll leave that to the next generation," and then he'd die.

He passed away at a conference in Warsaw #OTD in 1996, just after proving a new result.

Mathematician Bernhard Riemann was born #OTD in 1826.

He made deep contributions to complex analysis and number theory, but physicists remember him for his work on the foundations of geometry. These insights provide the mathematical framework for general relativity.