Professor Mareki Honma discusses the journey behind the first-ever successful imaging of a black hole

Special Session Looking at the Future of Technology

Professor Mareki Honma discusses the journey behind the first-ever successful imaging of a black hole

Mareki Honma
Director, Mizusawa VLBI Observatory, National Astronomical Observatory of Japan (NAOJ)
Professor, National Astronomical Observatory of Japan
Professor, Graduate University for Advanced Studies
Professor, Graduate School, The University of Tokyo
Mie Nagata
Chief Lecturer, Cosmo Planetarium Shibuya

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Black holes are astronomical objects that are shrouded in mystery, including their identity and even whether they exist. In 2019, however, mankind succeeded in catching a glimpse of this enigma.

Telescope Magazine talked with Mareki Honma (Professor at the National Astronomical Observatory of Japan, Director of the Mizusawa VLBI Observatory, and the person behind this great achievement) and Mie Nagata (Chief Lecturer at the Cosmo Planetarium Shibuya). In Part A of this special feature, we learned what sort of astronomical objects black holes are, how the image of a black hole was captured, and hopes for future research.

In Part B, our conversation moves to questions about black holes, whether or not extra-terrestrials exist, the appeal of science and astronomy, and the key to realizing dreams and a bright future.

Interview and text by Shinya Torishima; photographs by Honami Kawai, amana inc.

Mysteries surrounding black holes

Mareki Honma

Telescope Magazine: In Part A, you provided an overview of black holes, gave us a look behind the scenes at the successful imaging of a black hole shadow, and spoke about your hopes for future research. Could you now discuss the various mysteries and questions currently surrounding black holes?

Mie Nagata: During my lectures at the planetarium, visitors often ask what goes on inside a black hole, so how would it look if we actually entered a black hole?

Mareki Honma: I think it would certainly be beyond our imagination. An amazing spectacle would accompany us as we fell toward the center where everything collapses to a dark spot called a “singularity*1”.

Mie Nagata: You often hear that scary things would happen, like your body being stretched out.

Mareki Honma: That would happen in a small black hole. With a small black hole of only about 10 times the mass of our sun, like Cygnus X-1 (discussed in Part A), your body would be stretched thin like spaghetti and then smashed to pieces (figure 1).

But you can enter a supermassive black hole like the one we captured this time. And many great discoveries would be waiting for you there. Of course, once inside, you would never be able to leave. Nor communicate. So there would be no way of telling another human being what you found. Actually, I would like to enter a black hole at the end of my life. [laughs]

[Figure 1] Artist’s impression of the Cygnus X-1 black hole
Black holes are small astronomical objects, but this black hole is classified as a particularly small black hole due to it being about 10 times the mass of our sun.
© NASA/CXC/M.Weiss
Artist’s impression of the Cygnus X-1 black hole

Mie Nagata: People talk about white holes as well, being the opposite of black holes.

Mareki Honma: They are theoretically possible. Albert Einstein’s theory of general relativity predicts the existence of the two as a set—black holes that suck in anything and everything and the opposite white holes that just spit out matter.

Mie Nagata: So, if white holes exist, what would they look like?

Mareki Honma: Matter falling into a black hole appears to take an infinite amount of time, so with white holes being the opposite, they would appear to take an infinite amount of time to spit matter out. Although, if we could actually see that occur, it would mean that the white hole existed before the Big Bang itself, which makes it a very strange phenomenon. That is why at present many researchers tend to believe that white holes only exist mathematically, not in reality.

After Einstein developed his theory of general relativity, however, he could understand the possibility of black holes existing as astronomical objects, but he still did not believe that they existed. Because of the strangeness of such an astronomical object, he even wrote papers stating black holes did not exist. About 100 years later, we have now been able to prove their existence. Like that, people don’t currently believe in white holes but someday they might be found. In that future, people might laugh that some other people once doubted their existence...


Singularity: A singularity is thought to be located at the center of a black hole, where gravity is infinite and where normal laws of physics no longer apply.