A few weeks ago, an international team finally saw the results of years of planning, scheduling, and worrying. The drama played out on a single screen marshalled by a 29-year-old Dr Katie Bouman. She designed an algorithm that had spent the last two years analysing a staggering amount of digital data to render a blurry visual image. The image was none other than the enormous black hole sitting in the centre of Messier catalogue object M87. In the two years that her program had been running, Dr Bouman had gone from a post-grad student at Massachusetts Institute of Technology to an assistant professor of computing and mathematical sciences at the California Institute of Technology. But what does that little image really mean? What does it prove? Why should you and I care?
The story started in 1783 when one scientist, John Mitchell was pondering what happens if we fire a cannonball straight up. He wanted to understand what happens if the shot is so strong it flies away from Earth. The ‘escape velocity’ of earth is about 11km/s or around 7 miles/s. For the sun it is 617 km/s, but what if the escape velocity of a really heavy object is greater than the speed of light at 300,000km/s?
This question hung around until good old Einstein started to link gravity, space and time together in 1915. Even he missed the mark on some details, and the mantle was picked up by John Wheeler in the 1950s who followed work from Subrahmanyam Chandrasekhar in the 1930s. Chandra (whose nickname now lends itself to a modern orbital telescope) found that certain stars below a particular mass collapse to form a white dwarf star. Wheeler postulated that some massive stars over a certain limit may collapse into a dark body called a black hole. Wheeler also said that “Black holes have no hair” which was his way of saying that there was no detail or information discernible from outside a black hole. The maths seemed to prove it, but how do we take an observation of something that by definition is essentially invisible? For the next 50 or so years, we were able to take indirect observations that strongly supported these linked theories, such as studying how light bends under gravity. The theories grew and changed to match the observational data until we get to Dr Stephen Hawking. He strung together a few concepts and eventually realised that black holes would actually radiate heat, contrary to the supposition that nothing could escape a black hole’s gravity. In a more abstract way, it also showed that there could be information retained in the black hole, and further refinement showed that the information was in fact retained at the event horizon. Not only were black holes now hairy but Hawking seemed to prove they were also hot.
So, that brings us neatly back to the results of this latest effort. What the results now prove, is that the chain of minds and concepts that were followed, to a way to observe what the maths and theories seemed to suggest, were valid.
And why does that matter to you and I? Well, the thing about scientific theories is that they have a tendency to become fact, and from that fact, practical applications generally follow. Going forward into the next 50 or 100 years we cannot even begin to guess what may stem from the further research planned in this area, a chained black hole would provide limitless energy, freeing the world from oil, gas and coal dependency and saving the environment. One on the edge of the solar system could be used to accelerate and fire ships at near to light speed to other solar systems. If quantum entanglement continues to be fruitful it could even be possible to modulate a black hole and send signals instantaneously across the universe! I suspect our first signal might be “HELP!”
By David Lewis, Senior Research Analyst, Technical Department, Case Management Office.