Imagine that you are trying to take a photo of an orange that is on the moon with your smartphone. It seems impossible.
This is what scientists have tried to capture the image of a black hole in space. Despite the heavy task, an international team of more than 200 researchers unveiled Wednesday the very first image of a black hole.
Effort would not have been possible without Katie Bouman, who developed a crucial algorithm that allowed for the design of imaging methods.
Three years ago, Bouman led the creation of an algorithm that ultimately allowed to capture this unique image of its kind: a supermassive black hole and its shadow in the center of a galaxy known as M87. She was then a student in Computer Science and Artificial Intelligence at the Massachusetts Institute of Technology.
Black holes are extremely distant and compact, so it is difficult to take a picture of any of them. In addition, black holes, by definition, are supposed to be invisible – although they can clear a shadow when they interact with the material around them.
A global network of telescopes known as the Horizon Telescope Event Project has collected millions of gigabytes of data on M87 using a technique called interferometry. However, there were still major gaps in the data to be completed.
Its algorithm, and many others, have made it possible to fill the gaps
This is where Bouman's algorithm, along with several others, came into play. Using imaging algorithms like Bouman, the researchers created three scripted code pipelines to reconstruct the image.
They took "the sparse and noisy data" that the telescopes spat and tried to create an image. For a few years, Bouman has been managing the image verification and the selection of imaging parameters.
"We developed ways to generate synthetic data and used different algorithms. We also tested blindly if we could recover an image, "she told CNN.
"We did not want to develop a single algorithm. We wanted to develop many different algorithms incorporating different hypotheses. If all find the same general structure, it reinforces your confidence. "
The result? Revolutionary image of a ring structure, unbalanced, that Albert Einstein had predicted more than a century ago in his theory of general relativity. In fact, the researchers had generated several photos and they were all alike. The image of the black hole presented Wednesday did not come from a single method, but from all the different images of algorithms that were fuzzy.
"No matter what we did, you'd have to go crazy to get something that does not look like this ring," Bouman said.
Bouman was a crucial member of the imaging team
"(Bouman) was an important part of one of the imaging sub-teams," said Vincent Fish, a researcher at MIT's Haystack Observatory.
"One of the ideas that Katie provided to our imaging group is that there are natural images," Fish said. "Just think of the photos you take with your camera phone: they have certain properties. … If you know what a pixel is, you have a good idea of what's next to the pixel. "
For example, some areas are smoother and some areas are delineated accurately. The astronomical images share these properties and you can encode them mathematically, said Fish.
Junior members like Bouman made a significant contribution to the project, he added. Of course, experienced scientists worked on the project, but the imaging part was mainly run by young researchers, such as graduate students and post-docs.
"None of us could have done it alone," Bouman said. "It was done by lots of different people from all walks of life."
Bouman begins teaching as an assistant professor at the California Institute of Technology in the fall.