Article NASA celebrates Edwin Hubble’s discovery of another universe in 1923

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-Background- The popular consensus up until Edwin Hubble's finding in the 1923 had been that the Milky Way was the extent of the cosmos -- the only universe.

Etymology: Galaxies were initially discovered telescopically and were known as spiral nebulae. Most 18th- to 19th-century astronomers considered them as either unresolved star clusters or anagalactic nebulae, and were just thought of as a part of the Milky Way, but their true composition and natures remained a mystery. Observations using larger telescopes of a few nearby bright galaxies, like the Andromeda Galaxy, began resolving them into huge conglomerations of stars, but based simply on the apparent faintness and sheer population of stars, the true distances of these objects placed them well beyond the Milky Way. For this reason they were popularly called island universes, but this term quickly fell into disuse, as the word universe implied the entirety of existence. Instead, they became known simply as galaxies.

And the fact that they were initially called universes is echoed by the title of Edmond Hamilton's 1929 space opera novel "Outside the Universe". What today would instead be called outside the Milky Way galaxy.

The expanded world wasn't a total surprise, however. In 1755, Immanuel Kant had first speculated that some nebulae were actually island universes. This was -- in effect -- the first proposal for a multiverse.

The hypothesis was taken up by others over the course of more than 150 years, but had no confirming evidence until the 1920s.

The Great Debate: Curtis, on the other hand, contended that Andromeda and other such "nebulae" were separate galaxies, or "island universes" (a term invented by the 18th-century philosopher Immanuel Kant, who also argued that the "spiral nebulae" were extragalactic). He showed that there were more novae in Andromeda than in the Milky Way.

Throughout history, existence has repeatedly multiplied or proven to be vastly larger than what the current cultures of an era believed it to be. And as seen with the last major revision, after other realms are confirmed, the ensuing plural reference to "universes" is short-lived, with what formerly received the "universe" designation soon demoted to a new name or lesser classification.
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NASA celebrates Edwin Hubble’s discovery of a new universe
https://www.eurekalert.org/news-releases/1070621

INTRO: For humans, the most important star in the universe is our Sun. The second-most important star is nestled inside the Andromeda galaxy. Don't go looking for it — the flickering star is 2.2 million light-years away, and is 1/100,000th the brightness of the faintest star visible to the human eye.

Yet, a century ago, its discovery by Edwin Hubble, then an astronomer at Carnegie Observatories, opened humanity's eyes as to how large the universe really is, and revealed that our Milky Way galaxy is just one of hundreds of billions of galaxies in the universe ushered in the coming-of-age for humans as a curious species that could scientifically ponder our own creation through the message of starlight. Carnegie Science and NASA are celebrating this centennial at the 245th meeting of the American Astronomical Society in Washington, D.C.

The seemingly inauspicious star, simply named V1, flung open a Pandora's box full of mysteries about time and space that are still challenging astronomers today. Using the largest telescope in the world at that time, the Carnegie-funded 100-inch Hooker Telescope at Mount Wilson Observatory in California, Hubble discovered the demure star in 1923. This rare type of pulsating star, called a Cepheid variable, is used as milepost markers for distant celestial objects. There are no tape-measures in space, but by the early 20th century Henrietta Swan Leavitt had discovered that the pulsation period of Cepheid variables is directly tied to their luminosity.

Many astronomers long believed that the edge of the Milky Way marked the edge of the entire universe. But Hubble determined that V1, located inside the Andromeda "nebula," was at a distance that far exceeded anything in our own Milky Way galaxy. This led Hubble to the jaw-dropping realization that the universe extends far beyond our own galaxy.

In fact Hubble had suspected there was a larger universe out there, but here was the proof in the pudding. He was so amazed he scribbled an exclamation mark on the photographic plate of Andromeda that pinpointed the variable star.

As a result, the science of cosmology exploded almost overnight. Hubble's contemporary, the distinguished Harvard astronomer Harlow Shapley, upon Hubble notifying him of the discovery, was devastated. "Here is the letter that destroyed my universe," he lamented to fellow astronomer Cecilia Payne-Gaposchkin, who was in his office when he opened Hubble's message.

Just three years earlier, Shapley had presented his observational interpretation of a much smaller universe in a debate one evening at the Smithsonian Museum of Natural History in Washington. He maintained that the Milky Way galaxy was so huge, it must encompass the entirety of the universe. Shapley insisted that the mysteriously fuzzy "spiral nebulae," such as Andromeda, were simply stars forming on the periphery of our Milky Way, and inconsequential.

Little could Hubble have imagined that 70 years later, an extraordinary telescope named after him, lofted hundreds of miles above the Earth, would continue his legacy. The marvelous telescope made "Hubble" a household word, synonymous with wonderous astronomy.

Today, NASA's Hubble Space Telescope pushes the frontiers of knowledge over 10 times farther than Edwin Hubble could ever see. The space telescope has lifted the curtain on a compulsive universe full of active stars, colliding galaxies, and runaway black holes, among the celestial fireworks of the interplay between matter and energy... (MORE - details, no ads)

(1929) Outside the Universe by Edmond Hamilton ... https://youtu.be/7ntcFINsQRQ

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