Tag Archives: Milky Way

Black hole discoveries win 2020 Nobel Prize in Physics

By Niklas Pollard and Douglas Busvine

STOCKHOLM/BERLIN (Reuters) – Britain’s Roger Penrose, Reinhard Genzel of Germany and American Andrea Ghez won the 2020 Nobel Prize for Physics on Tuesday for their discoveries about one of the most exotic phenomena in the universe, the black hole.

Penrose, professor at the University of Oxford, won half the prize of 10 million Swedish crowns ($1.1 million) for his work using mathematics to prove that black holes are a direct consequence of Albert Einstein’s general theory of relativity.

Genzel, of the Max Planck Institute and University of California, Berkeley, and Ghez, at the University of California, Los Angeles, shared the other half for discovering that an invisible and extremely heavy object governs the orbits of stars at the center of our galaxy.

Ghez – only the fourth woman to be awarded the Physics prize after Marie Curie in 1903, Maria Goeppert-Mayer in 1963 and Donna Strickland in 2018 – said she hoped it would inspire others.

Asked about the discovery of a massive yet invisible object at the heart of the Milky Way, Ghez said “the first thing is doubt”.

“You have to prove to yourself that what you are really seeing is what you think you are seeing. So, both doubt and excitement,” the 55-year-old astronomer said in a call with the committee after receiving the award.

“It’s that feeling of being at the frontier of research when you have to always question what you are seeing.”

Genzel, 68, told Reuters Television soon after hearing he had shared the prize that had been on a Zoom call with colleagues when the phone rang.

“Just like in the movies, a voice said: ‘This is Stockholm’,” he said. He admitted to being flabbergasted by the news: “I cried a little bit.”

WHERE TIME ENDS

Scientists have wondered since the 18th century whether any object existed in the universe that would exert a gravitational pull so strong that light may not be able to escape.

Einstein predicted in 1915, in his general theory of relativity, that space and time could be warped by the force of gravity. Yet he did not actually believe in black holes, and finding a way to prove their existence baffled scientists for another 50 years.

“It was a theory – there was nothing to make black holes visible,” said Genzel.

It was not until a seminal paper in 1965 that Penrose, now 89, proved that black holes can really form – describing them in detail and stating that, at their center, time and space cease to exist.

Illustrating Penrose’s insight at the awards presentation in Stockholm, Ulf Danielsson of the Nobel Committee held a black ball the size of a grapefruit in one hand and pointed at it with the finger of his other hand.

At the ball’s edge, time stands still, Danielsson said, and as his finger pushed into it, its tip moves into the future.

It would be impossible to withdraw one’s finger without tearing it apart. Instead it would be “carried all the way into the center of the black hole, where time ends and the known laws of physics cease to apply”.

‘AWE-INSPIRING’ MYSTERY

Subsequent efforts to find a black hole focused on the clouds of dust in a region of the Milky Way called Sagittarius A*. By observing movements of stars, teams of astronomers led by Genzel and Ghez concluded that around 4 million solar masses are packed into a region the size of our solar system.

“Penrose, Genzel and Ghez together showed us that black holes are awe-inspiring, mathematically sublime, and actually exist,” said Tom McLeish, professor of natural philosophy at Britain’s University of York.

While black holes are now accepted science, much about them remains a mystery.

“What is the black hole? We don’t know, we have no idea what is inside a black hole and that is what makes these things such exotic objects,” said Ghez.

Physics is the second of this year’s crop of Nobels to be awarded, after three scientists won the medicine prize for their discovery of Hepatitis C on Monday.

The Nobel prizes were created in the will of Swedish dynamite inventor and businessman Alfred Nobel and have been awarded since 1901.

This year’s awards are taking place under the long shadow of the COVID-19 pandemic that has curtailed much of the usual festivities surrounding the prizes. ($1 = 8.9108 Swedish crowns)

(Reporting by Niklas Pollard and Douglas Busvine; Additional reporting by Johannes Hellstrom, Supantha Mukherjee, Simon Johnson, Colm Fulton and Anna Ringstrom; Editing by Alex Richardson)

Scientists puzzled by exotic distant galaxy lacking dark matter

The galaxy named NGC 1052-DF2, a large fuzzy-looking galaxy so diffused that astronomers call it a 'see-through' galaxy because its missing most, if not all of its dark matter, is shown in this photo obtained from NASA on March 28, 2018. NASA, ESA, and P. van Dokkum (Yale University)/Handout via REUTERS

By Will Dunham

WASHINGTON (Reuters) – Astronomers have detected for the first time a galaxy that is devoid of dark matter, the plentiful but enigmatic material that does not emit light or energy and had been considered a fundamental part of all galaxies including our own Milky Way.

The discovery, announced on Wednesday, is forcing scientists to rethink their ideas about the formation of galaxies.

“We didn’t expect that this could happen,” said Yale University astronomer Pieter van Dokkum, lead author of the research published in the journal Nature.

Paradoxically, the discovery of a galaxy without dark matter may actually confirm that the stuff actually exists by contradicting hypotheses advanced by dark matter doubters.

Van Dokkum said the galaxy, called NGC1052-DF2 and located about 65 million light years away from Earth, also appears to be devoid of gas and is relatively sparsely populated by stars.

It is about the same size as the Milky Way, but has roughly 250 times fewer stars: 400 million compared to the Milky Way’s 100 billion stars. It is classified as an ultra-diffuse galaxy, a kind first recognized in 2015.

Dark matter, which is invisible, is thought to comprise about a quarter of the universe’s combined mass and energy and about 80 percent of its total mass, but has not been directly observed. Scientists believe it exists based on gravitational effects it seems to exert on galaxies.

The universe’s ordinary matter includes things like gas, stars, black holes and planets, not to mention shoes, umbrellas, platypuses and whatever else you might see on Earth.

“Dark matter is not something that galaxies can sort of swap in or out of, like it’s kind of an optional thing that galaxies sometimes have and sometimes don’t,” van Dokkum said.

“We really thought that this is the essence of what a galaxy is, that galaxies are built from, initially, a bunch of dark matter and that all the stars and all the planets and everything else is just a little frost on top,” van Dokkum added.

The scientists spotted NGC1052-DF2 using the Dragonfly Telephoto Array, a telescope in New Mexico. They do not know how it formed, but have some hypotheses, including the possibility that a cataclysm within NGC1052-DF2 swept away all its gas and dark matter or that a massive nearby galaxy played havoc with it.

Van Dokkum said NGC1052-DF2 is so sparse that “it is literally a see-through galaxy.”

(Reporting by Will Dunham; Editing by Sandra Maler)