蓝莓视频

鈥淚t turns out our predictions were stunningly close; we were spot-on,鈥� said Broderick. 鈥淚 think this is a stunning confirmation that we are at least on the right track of understanding how these objects work.鈥�

For Broderick, a professor at University of 蓝莓视频 and the Perimeter Institute for Theoretical Physics, and a key member of the international Event Horizon Telescope Collaboration, this wasn鈥檛 just an image that proved his theoretical models correct, it was the beginning of a historic journey into the unknown, with potentially revolutionary consequences that will reverberate through science and society as a whole.

Making the impossible possible

On April 10, the global collaboration showcased the first image of the supermassive black hole in the core of the massive elliptical galaxy M87. The image shows a ghostly bright crescent surrounding a dark disk, a feature that surrounds the most gravitationally extreme region known: a black hole鈥檚 event horizon. This first image isn鈥檛 only proof that humanity now has the ability to probe right up to the edge of an event horizon, it鈥檚 a promise that future observations will help us better understand how supermassive black holes work, how they drive the evolution of their galactic hosts and, possibly, reveal new physics by finally unmasking the true nature of gravity itself.

To Broderick, who has always been fascinated by the undiscovered, it鈥檚 mysteries like these that give him the passion to understand how the universe works 鈥� an adventure that is an important part of the human story.

鈥淏lack holes are the most extreme environments in the universe, so naturally I was hooked for as long as I can remember,鈥� he said. 鈥淣owhere in the universe is there a more perfect laboratory for pushing back the boundaries of our knowledge of gravity鈥檚 nature. That makes black holes irresistible.鈥�

Few scientists would debate the reality of black holes, but the first image of M87鈥檚 supermassive black hole is definitive proof that these monsters, and their associated event horizons, exist. 鈥淭hese things are real, along with all the consequences for physics,鈥� he said.

In the years preceding this announcement, Broderick and his EHT colleagues developed simulations that modeled what the Earth-spanning virtual telescope might see. And, on comparing his models with the first EHT image, Broderick was amazed.

鈥淭hat first image was so good that I thought it was a test 鈥� it had to be a trial run,鈥� said Broderick, 鈥淚t鈥檚 a beautiful ring shape that鈥檚 exactly the right size. In fact, it looks very similar to the images (of theoretical models) we included in proposals for the EHT.鈥�

The ring shape Broderick describes is the bright emissions from the hot gasses immediately surrounding the colossal maw of a supermassive black hole鈥檚 event horizon. Located inside the massive elliptical galaxy M87 in the constellation of Virgo, this gargantuan object has a mass of six-and-a-half-billion Suns and measures nearly half a light-day across. This may sound big, but because it鈥檚 located 55-million light-years away, it鈥檚 far too distant for any single telescope to photograph.

The EHT, however, is a network of many radio telescopes around the world, from the Atacama Desert to the South Pole. By working together 鈥� via a method known as very long-baseline interferometry 鈥� they create a virtual observatory as wide as our planet and, after two decades of development, the international collaboration has accomplished the impossible by resolving the event horizon around M87鈥檚 supermassive black hole.

鈥淭his is a project that has a wide breadth of collaboration, geographically 鈥� you can鈥檛 build an Earth-sized telescope without an Earth-sized collaboration! 鈥� but also in expertise, from the engineers who build these advanced telescopes, to the astronomers who work on the day-to-day and the theorists who inspire their observations,鈥� said Broderick.

A stunning confirmation

The event horizon is a region surrounding a black hole where the known physics of our universe ends abruptly. Nothing, not even light, can escape a black hole鈥檚 incredible gravity, with the event horizon being the ultimate point of no return. What lies beyond the event horizon is open to debate, but one thing is for certain: if you fall inside, you鈥檙e not getting out.

Over a century ago, Albert Einstein formulated his theory of general relativity, a theoretical framework that underpins how our universe works, including how event horizons should look. Black holes are the embodiment of general relativity at its most extreme, and event horizons are a manifestation of where space-time itself caves in on itself.

鈥淓vent horizons are the end of the safe space of the universe,鈥� said Broderick, 鈥渢hey should have 鈥榤ind the gap鈥� or 鈥榤ind the horizon鈥� signs around them!鈥�

Physics has some key unresolved problems that may be answered by the EHT, one of which is the nature of gravity itself, added Broderick. Simply put, gravity doesn鈥檛 jibe with our current understanding of other fundamental forces and particles that underpin all matter in the universe. By stress-testing Einstein鈥檚 theories right at the edge of a black hole鈥檚 event horizon, the EHT will provide physicists with the ultimate laboratory in which to better understand gravity, the force that drives the formation of stars, planets, and the evolution of our universe.

Once we truly understand this fundamental force, the impact could be revolutionary, said Broderick. 鈥淕ravity is the key scientific problem facing physics today, and no one fully understands the ramifications of what understanding gravity fully are going to be.鈥�

On an astronomical level, supermassive black holes are intrinsically linked with the evolution of the galaxies they inhabit, but how they form and evolve together is another outstanding mystery.

Supermassive black holes are also the purveyors of creation and doom 鈥� they have the power to kick-start star formation as well as preventing stars from forming at all 鈥� a dichotomy that astronomers hope to use the EHT to understand.

鈥淭hese incredibly massive things lie at the centers of galaxies and rule their fates,鈥� said Broderick. 鈥淪upermassive black holes are the engines behind active galactic nuclei and distant quasars, the most energetic objects known. Now we鈥檙e seeing what they look like, up close, for the first time.鈥�

All galaxies are thought to contain a supermassive black hole, including our own galaxy, the Milky Way. Called Sagittarius A* (or Sgr A*), our supermassive black hole is 2,000 times less massive than the one in M87, but it鈥檚 2,000 times closer 鈥� at a distance of 25,000 light-years. This means that the EHT can image both Sgr A* and M87 as they appear approximately the same size in the sky, a situation that is an incredible stroke of luck.

鈥淚f you had to choose two sources, these two would be it,鈥� said Broderick. Whereas M87鈥檚 supermassive black hole is one of the biggest known and a 鈥渞eal mover and shaker,鈥� Sgr A* is much less massive and considered to be an 鈥渆veryman of black holes,鈥� he said.

鈥淲e had to start somewhere. M87 represents the first end-to-end exercise of the entire EHT collaboration 鈥� from data taking to data interpretation,鈥� said Broderick. 鈥淭he next exercise will happen considerably faster. This is only the beginning.鈥�

Voyage of discovery

As the scientific benefits of observing supermassive black holes are becoming clear, Broderick pointed out that the impact on society could also be seismic.

鈥淚 would hope that an image like this will galvanize a sense of exploration; an exploration of the mind and that of the universe,鈥� he said. 鈥淚f we can excite people, inspire them to embark on a voyage of discovery in this new EHT era of observational black hole physics, I can only imagine that it will have profound consequences for humanity moving forward.

鈥淚 feel incredibly privileged to be a part of this story of exploration 鈥� the human story of understanding the universe we inhabit and using that understanding to improve our lives.鈥�