On the 10th of April 2019, scientists unveiled the first picture of a black hole. This was a historic feat, which was once considered impossible. It’s 500 million trillion km away from Earth. As such, the feat is described as trying to take a picture of an orange on the surface of the moon with your phone. Here’s how a team of 200 researchers did it.
The origins of this scientific feat
According to BBC, Prof. Heino Falcke, of Radboud University in the Netherlands, initially proposed the experiment. The year was 1993 and nobody thought it could be done. However, Prof. Falcke argued otherwise. His argument was based on two factors.
The first was that a certain type of radio emission generated close to and around the black hole. These could be powerful enough to be detected by telescopes on Earth. The second was according to a scientific paper from 1973, black holes appear 2.5 times larger than they actually are. This is due to their enormous gravity.
Prof. Falcke argued his case for 20 years. Until finally, he persuaded the European Research Council to fund the project. Afterward, the National Science Foundation and a host of agencies in East Asia also agreed to fund the project. This gave the project a total of $50 million in funding and with it, work began on this scientific feat.
Building a telescope as large as the Earth itself
The first hurdle the project had to overcome was the telescope. The black hole is located in at the heart of Messier 87, or M87, a galaxy within the Virgo galaxy cluster. It’s 55 million light years away from Earth. No single telescope on the planet is powerful enough to see anything that far away.
In fact, the project required a telescope the size of planet Earth itself. This person led the efforts to create such a telescope was Prof. Sheperd Doeleman of the Harvard-Smithsonian Centre for Astrophysics. His solution to the daunting challenge was to create a network of eight telescopes.
These eight telescopes were located in exotic locations like Antarctica, volcanoes in Hawaii, the Spanish Sierra Nevada, and in the Atacama Desert of Chile. When connected together, they became the Event Horizon Telescope – a virtual telescope the size of planet Earth.
Normally each telescope would operate independently. Furthermore, they were all located on different continents. But through a technique called VLBI, it was possible to combine the power of these telescopes. By doing so, it allowed the team to get the exact precision to view a black hole, as predicted by Einstein’s original equations.
Looking into a black hole
On the 5th of April 2017, the Event Horizon Telescope began observing the black hole. MIT describes the process as, “In radio astronomy, telescopes detect radio waves, at frequencies that register incoming photons as a wave, with an amplitude and phase that’s measured as a voltage. As they observed M87, every telescope took in streams of data in the form of voltages, represented as digital numbers”
The Event Horizon Telescope observed the black hole in this manner for a number of days. By the time it was done, each telescope had collected 1 petabyte of data. To store all that data, you’d need a thousand 1TB hard drives. Yet, this is exactly what the researchers at these observatories did.
They packed stacks of hard drives and had them shipped via FedEx to processing centers. One processing center was the Haystack Observatory, in Massachusetts. The second was the Max Planck Institute for Radio Astronomy, in Germany. At these locations, the data was processed by a specialized supercomputer known as a correlator.
These teams along with the correlator were tasked with eliminating noise. This was because the data received by two separate telescopes may encode the signal of the black hole. But it would also contain noise. Eliminating this and fixing other problems unique to each individual telescope was the challenge faced by the teams at these processing centers.
Once the issues were fixed, the data was fed into the correlator once again. Only after rigorous verification, was this raw data released to four separate teams around the world. Each of these teams would be tasked with generating the final image we saw using this data with a variety of independent techniques.
Recreating the image of a black hole
Even with the Event Horizon Telescope, there were gaps in the data. Furthermore, astronomical signals reach telescopes at slightly different times. To create an accurate image of anything in our universe, it’s essential to account for this difference. This was where the algorithms by computer scientists in four separate imaging teams came to play.
One of these computer scientists was Katie Bouman, a grad student at MIT. During a TEDx Talk she said, “What would happen if Einstein’s theories didn’t hold? We’d still want to reconstruct an accurate picture of what was going on. If we bake Einstein’s equations too much into our algorithms, we’ll just end up seeing what we expect to see.”
This was the challenge that each of the four imaging teams faced. It was precisely for this reason that the project had four separate imaging teams. Each of these teams operated independently without any communication between themselves. The goal of each team was to apply their individual techniques and tests to recreate the image of the black hole.
The aim of keeping these imaging teams disconnected was to combat any bias. It was essential for the team to do this, as we had never seen a black hole before. Therefore, if four separate teams operating individually could recreate similar images from the telescopic data, then the entire team could be confident of the final image.
Thankfully, for the entire team this was what exactly happened. Each of the four imaging teams, applying their individual techniques and tests, had come to the same conclusion. They all had recreated images of the black hole surrounded by a bright orange ring. Einstein was right and everyone can now say that with confidence.
Recognizing everyone involved in this feat
It took a team of 200 researchers across the world to capture the first picture of a black hole. It was a feat that required building a massive telescope, capturing tons of data, shipping it across the world to supercomputers, and new algorithms.
This was how we looked deep into the cosmos to see a phenomenon that’s three million times larger than our planet. That one picture should’ve reminded us just how tiny we are in the grand scale of the universe. Yet, this news ended up highlighting deep problems in science and technology.
When the news broke out, many publications praised Katie Bouman. They stated that it was her algorithm that made it possible for us to get this picture. Soon afterward, accusations were made in an attempt to discredit her. These accusations stated that Andrew Chael, another astrophysicist on the team was the primary contributor.
In response, Andrew took to Twitter to dispell these false accusations. He reminded everyone that Katie had made immense contributions as a member of the imaging team. And this highlights the greater issue women face in being recognized for their contributions in science and technology.
Nobody made memes accusing Prof. Heino Falcke of not being the one that originally proposed this experiment. Similarly, nobody doubted the efforts of Prof Sheperd Doeleman who lead the team to build the Event Horizon Telescope.
Yet, as we dig deeper, we find that the cause of this incident could also be attirbuted to another fundamental problem. That problem being that it’s very easy for the media to get things wrong when reporting about complex science and technology. Many of the publications that originally praised Katie, did so in a manner that distorted the truth.
They gave the impression that it was Katie who created an invaluable algorithm that made it possible for us to obtain the image of the black hole. But this was a massive distortion of the truth. But as we mentioned earlier, there were four independent imaging teams. Each one applied their own individual techniques.
Furthermore, Dr. Kazunori Akiyama, an imaging coordinator on the project stated that there were other women who helped lead these imaging teams as Katie did. One of these women was Sara Issaoun, a Ph.D. student at Radboud University, who stated that Katie’s original algorithm wasn’t even used to recreate the final image!
Nonetheless, Dr. Kazunori went onto state, “We didn’t use exactly her algorithm from her TED talk, but her work was foundational along with a lot of other contributions in building the final procedure for all imaging pipelines.” Katie Bouman had made valuable contributions in the effort to obtain this iconic image of a black hole.
As did the many others involved in this project. The credit for this feat does not belong to any single person. It belongs equally to all the 200 researchers from different backgrounds, genders, and nationalities. So when we celebrate this in the years to come, may it serve as a reminder of what we can accomplish through collaboration.