“It turns out that the material falling into a black hole becomes so hot, emitting lots of light, and the light is bent by the gravity of the black hole. It’s expected to be bent into a ring shape that’s surrounding the shadow cast by the black hole on the emission. So, that’s what we’re trying to take a picture of.” – Michael Johnson, Ph.D., Astrophysicist, Harvard-Smithsonian Center for Astrophysics
April 27, 2018 Cambridge, Massachusetts – No human has yet photographed a black hole in this universe. First, it seemed impossible if black holes grab everything around them, including light, and don’t even let the photons out that could reach an Earth telescope camera. Physicist Albert Einstein couldn’t see them either, but his mathematical calculations about gravity curving and stretching Space-Time produced the concept of mysterious black holes throughout this universe that have a singularity at their center where all surrounding mass is crushed by gravity to a single point.
Before that annihilation zone, there is another place surrounding a black hole called the Event Horizon. Einstein said that all matter — even light photons — that cross the Event Horizon will disappear from this universe. But before that happens, it is possible for gasses and matter to orbit a black hole without falling in. That’s called an “accretion disk.” That’s the last stop outside the strong gravitational pull of black holes where light photons can escape back to our telescopes and cameras.
Right at the center of our Milky Way Galaxy is a supermassive black hole (SMBH) about 4.5 million times the mass of our Sun. It’s called Sagittarius A*. Now in 2018, a group of astrophysicists and astronomers are working for the first time to get an actual image of our Milky Way’s black hole — or at least a “shadow” of its Event Horizon cast onto the accretion disk of gas and dust that orbits the black hole without falling in. To get that actual black hole shadow image, scientists are constructing an array of radio telescopes and very-long-baseline interferometry stations around our whole planet. It’s called the Event Horizon Telescope and this will be the first human-made technology the size of Earth.
Ironically, there would be nothing to photograph if the supermassive black hole did not curve space-time so strongly that scientists say it should be possible to see parts of the accretion disk behind the black hole. Further, Earth scientists need an Event Horizon big enough to see from Earth. The Milky Way’s central black hole is 4.5 million times the mass of our Sun — and our Sun is 864,337 miles in diameter. So, the supermassive black hole at the center of our Milky Way galaxy is about the size of our solar system! That means the shadow it casts on its accretion disk of gas and dust should be big enough for the new Earth-sized Event Horizon Telescope to actually see. But the challenge is a bit like trying to make an image of a quarter coin in Los Angeles from a camera in New York City!
When computer models are run to calculate what the first ever black hole image could look like, the result is a toroidal ring of ionized matter. And if all goes well, we might all be able to see how accurate the computer projections have been by the end of this year in December 2018.
Collaborating with the Event Horizon Telescope investigators is Astrophysicist Michael Johnson, Ph.D., at Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. Prof. Johnson says it is now considered a fact that every galaxy in our universe has a black hole at its center and he is enthusiastic about finally seeing the first image of light bent by the strong gravity of the Milky Way’s supermassive black hole. Recently I talked with Prof. Johnson about his Event Horizon telescope work and other black hole mysteries.
Michael D. Johnson, Ph.D., Astrophysicist, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts: “I’m part of this group now that’s trying to take a picture of a black hole and to see what one would actually look like. These are observations in the near-infrared. It turns out that the material falling into a black hole becomes so hot, emitting lots of light, and the light is bent by the gravity of the black hole. It’s expected to be bent into a ring shape that’s surrounding the shadow cast by the black hole on the emission. So, that’s what we’re trying to take a picture of.
LIKE A TORUS?
Yeah, it’d look sort of like a crescent moon, we think is one possibility.
YOU WOULD BE TAKING THIS PHOTOGRAPH IN A VERY SPECIFIC WAVELENGTH OF INFRARED?
This would actually be taken at a little longer wavelength at about 1.3 millimeters using a telescope that’s effectively the size of the Earth called the Event Horizon telescope.
RIGHT. WHEN DO YOU THINK THAT YOU MIGHT HAVE THE FIRST IMAGE OF A BLACK HOLE?
Well, we don’t know. A big part of the difficulty is we don’t yet know what we’re going to see. We’re hoping that in the next year or two that we’ll have these first images.
If Every Galaxy In This Universe Has A Central Black Hole — Why?
We think that every galaxy does harbor a black hole at its center. Larger galaxies have larger black holes in them.
IF SO, WHY?
The best evidence really comes from our own galactic center, and in our own galactic center, we can actually see stars orbiting the black hole. And the tightest star orbits have periods of just more than a decade or so. We’ve actually now traced out their orbits. They take an entire loop around this black hole, and you see this bright star is moving around something that appears not to exist. It’s remarkable.
IT SEEMS SO PARADOXICAL THAT THROUGHOUT THE UNIVERSE THAT THE MATTER WORLDS, THE MATTER GALAXIES WOULD BE MARRIED TO SOMETHING THAT ANNIHILATES MATTER AT ITS CENTER.
Black holes don’t annihilate matter. I mean, if matter falls into a black hole, it becomes part of the black hole, and it will increase the mass of the black hole by the amount of mass that the object had when it was sitting outside. It’s not that they’re destroying matter. They’re just condensing it down to the singularity. But then that action of the black hole and its continued interaction with the matter is an important part of the life cycle of the galaxy.
ONCE THAT MATTER GOES INTO A BLACK HOLE, IF I’M UNDERSTANDING CORRECTLY, IT’S NEVER SUPPOSED TO COME OUT, AT LEAST IN THIS UNIVERSE THAT IS BEING ABSORBED BY THE BLACK HOLE.
WELL, CAN YOU EXPLAIN WHAT YOU THINK IS THE REASON FOR THIS MARRIAGE BETWEEN BLACK HOLES AT THE CENTER OF EVERY GALAXY IN THE UNIVERSE? WHY ARE THERE BLACK HOLES AT ALL?
Black holes are sort of an endpoint where you can pour material in and you can’t pull it back out. It’s counterintuitive, and it’s something that you wouldn’t predict from Newtonian gravity. This is a concept that arises in the Theory of General Relativity where there aren’t gravitational forces anymore, but all that happens is that mass curves spacetime. And so this is a consequence of how mass curves spacetime and how light is affected and how the motion of the material near a black hole is affected.
IF YOU WERE TAKING THE POSITION OF GOD, IN THE SENSE OF THAT WHICH IS INCOMPREHENSIBLE, THAT WHICH THERE HAS TO BE A SOURCE FOR THIS MATTER UNIVERSE, WHY WOULD YOU HAVE CREATED A UNIVERSE IN WHICH THERE HAS TO BE A BLACK HOLE AT THE CENTER OF EVERY GALAXY?
Well, I don’t think there has to be a black hole at the center of every galaxy. If you were God, and you could just paint a galaxy however you like it, you could certainly start one off that has no black hole in it. You could just fill it with stars and fill it with planets and let it go. And over time, what you would see is that it would tend to form black holes. As the stars lived and died, some of them would collapse down to black holes, and as the material accreted towards the center of the galaxy, the material could eventually become a black hole. So, it’s sort of a natural endpoint of this gravitational collapse.
Star Deaths Make Black Holes
IF I’M UNDERSTANDING, THE VERY NATURE OF HAVING LARGE MASSES OF THINGS LIKE STARS, AND THAT THE STAR ITSELF HAS A LIFE AND DEATH CYCLE, ALL THE STARS DO, THAT IT IS THE COLLAPSE OF THE ABILITY TO REMAIN BEING A STAR, AND THAT BIG COLLAPSE OF THE GRAVITATIONAL FORCES PULLING ON THE MATTER OF THE STAR END UP COMPRESSING IT, AND THAT IN THE COMPRESSION, THERE IS THE CREATION OF A BLACK HOLE.
That is exactly right. Normal material doesn’t just collapse down into a black hole because it’s held up by its own internal structure. For some materials, that can be quite strong. But if you pile enough material on, eventually, it will collapse down. Stars are held up by the heat that’s being produced at the core of the star as they’re driving fusion. But if they run out of fuel to drive that fusion, they don’t have that heat source anymore, and so it’ll collapse down. And as you collapse down smaller and smaller, that’s when it’s held up by these quantum mechanical effects, and eventually even those lose to gravity, and that’s when it’ll collapse down small enough to become a black hole.
SO, DO YOU THINK THAT AT THE BEGINNING OF THE SINGULARITY THAT IS A BIG MYSTERY ITSELF AND THE EVOLUTION OF HYDROGEN AND HELIUM AND ONWARD INTO MATTER AND OTHER ELEMENTS THAT THE BLACK HOLE CAME INTO EXISTENCE ONLY AFTER THERE HAD BEEN STARS CREATED?
Right. For the black holes that we’re studying today, they probably came into existence long after the first stars formed.
WE WOULDN’T HAVE BLACK HOLES IF THERE WEREN’T STARS. AND THAT IT IS THE FIRST EXISTENCE AFTER THE SINGULARITY OF STARS EVOLVING INTO GALAXIES THAT THEN SET UP SOME KIND OF DANCE WITH GRAVITY THAT WHEN THE STARS DIE, THERE IS GOING TO BE A COMPRESSION THAT WILL AUTOMATICALLY LEAD TO A BLACK HOLE.
Yeah. The death of a star is maybe the simplest pathway to forming a black hole. There are other ways to make a black hole, but a collapse of a star is one of the ways you can be really sure for certain types of stars that the end result of that will be a black hole.
Can Milky Way Black Hole Pulse Energy That Interacts With Our Solar System?
CAN THERE BE PERIODIC PULSES OF ENERGY FROM THE MILKY WAY GALAXY’S BIG BLACK HOLE AT THE CENTER?
In certain ways we might expect to see periodic pulses associated with black holes. One would be if you had some hot region in the plasma near the black hole, it’s going to be orbiting around the black hole, and that’s because it’s actually very difficult to fall into a black hole. Kind of paradoxical. It’s one of these deep mysteries associated with black holes, which is how does matter fall in? The reason that’s hard is for the same reason we don’t just fall into the sun. We sit on an orbit around the sun. And that’s because the Earth has angular momentum, so if the Earth were to fall into the sun, we would have to give that angular momentum to another object so that we could fall inward. Likewise, for material that’s around a black hole, it won’t just plunge into the black hole unless it’s very close. It’ll normally just sit there on a circular orbit. And so there has to be some mechanism that drives material into a black hole.
WHAT IS THAT MECHANISM?
So, this was a mystery for a long time, and now we think that the mechanism that allows black holes to eat is turbulence that’s driven by a magnetic instability in the material near a black hole. We think that it’s sort of tangled magnetic fields near the black hole that are providing the friction that allows the material to transfer its angular momentum so that some of it can fall into the black hole.
SO, IF THE BLACK HOLES THROUGHOUT THE UNIVERSE ARE EATING WHATEVER MATTER HAPPENS TO GET PAST THAT RIM, IS IT POSSIBLE FOR THE BLACK HOLES TO BURP OUT ENERGY AND MIGHT RELATE TO PERIODIC CYCLES OF EXTINCTION OR STRANGE MOMENTS IN OUR PAST WHERE THERE APPEARS TO HAVE BEEN MAYBE BIG FLOODS OR BIG FIRES OR SOMETHING THAT MIGHT BE RELATED TO CYCLES BETWEEN THE BLACK HOLE AND THE MILKY WAY GALAXY?
There are two parts to the answer to that question. The first is material falling toward the black hole can be ejected from the black hole as long as it hasn’t crossed the event horizon. So, it can be falling inward, and maybe it’s changing some of its gravitational energy and the heat as it’s falling inward, lighting up. This is why the centers of galaxies can be very bright. But black holes also tend to launch these very powerful jets. So, material might fall inward, but then it can get launched out in a different direction carrying quite a lot of energy. And that can happen as long as it hasn’t actually fallen into the black hole.
WHAT IS THE EVENT HORIZON?
The event horizon is the special place in spacetime that delineates whether or not material has transitioned to this region where nothing can escape, not even light.
Do Black Holes Create White Holes?
WHAT IS CURRENTLY THE THEORETICAL PERSPECTIVE ON ONCE IT HAS PASSED THE EVENT HORIZON, WHERE IS THE MATTER AND THE ENERGY ENDING UP?
Right. That’s a very deep question, and from the perspective of an observer like us sitting outside the black hole, there are lots of equivalent ways of answering that question that all lead to the same predictions. So, the problem is you can have different ideas about what happens there, but those differences wouldn’t actually affect any experiment that we could design to study it outside the black hole.
WHAT DO YOU THINK?
(Laughs) I choose not to speculate on those things.
WHAT DO YOU THINK WOULD HAPPEN IF WE BUILT A DRONE PROBE TO GO INTO A BLACK HOLE?
Well, if the probe could communicate with us, it could send us lots of information as it was falling into the black hole. And as it got closer to the event horizon, the information that it would get to us would be stretched out in time. So, we’d sort of get less and less information until it finally crossed the event horizon, and at that point, we would stop receiving any transmissions.”
Milky Way’s Center Could Have 10,000 Black Holes!
The April 16, 2018, issue of the science journal Nature featured new research of X-ray observations that have revealed a dozen stellar-mass black holes at the centre of the Galaxy, implying that there could be ten thousand more to be confirmed.
12-21-2016 – Part I: Is Our Universe “Someone Else’s” Computer Simulation?
12-21-2016 – Part 2: Is Our Universe “Someone Else’s” Computer Simulation?
06-27-2015 – Is Time An Illusion and the Future Already Written, As Einstein Thought?
06-26-2015 – Artificial Intelligence, Androids and Robots: Do They Threaten Human Civilization?
05-25-2014 – Part 2: More About “Hostile Alien Visitors” in Pres. Ronald Reagan Briefing
07-26-2013 – Unidentified Cosmic Radio Bursts Baffle Astronomers
Most Detailed Star Map of Milky Way Galaxy by ESA, April 25, 2018: http://www.esa.int/Our_Activities/Space_Science/Gaia/Gaia_creates
“Bounteous black holes at the Galactic Centre,” April 16, 2018, Nature: https://www.nature.com/articles/d41586-018-04341-8
Event Horizon Telescope: https://eventhorizontelescope.org
© 1998 - 2018 by Linda Moulton Howe.
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