Was it really a black hole that the EHT imaged in 2019?

The debate among physicists takes off over alternative possibilities such as naked singularities into the realms of time travel and loops of time

In 2019, astronomers of the Event Horizon Telescope captured the first ever image of a supermassive black hole (M87*) which was located at the centre of a galaxy Messier 87 (M87). This black hole is calculated to be 6.5 billion times the Sun’s mass and is 55 million light years away from the Earth. The discovery set the world of astronomy on fire and also found a mention in the “popular information” section of the announcement of the Nobel Prize in physics for 2020, when Andrea Ghez and Rheinhard Genzel were awarded half the share of the prize for their study of the black hole at the centre of the Milky Way galaxy, Sagittarius A*.

Now, a paper published in The European Physical Journal C brings in an alternative explanation for the compact object that was imaged by the Event Horizon Telescope. The authors say it (M87*) is not necessarily a black hole but could even be a “naked singularity with a gravitomagnetic monopole.”

When stars much more massive than the Sun reach the end of their lives, they collapse under their own gravity, and the product of this collapse, most astronomers believe is a black hole. A black hole has two parts: At its core is a singularity – a point that is infinitely dense, as all the remnant mass of the star is compressed into this point. Then there is the event horizon – an imaginary surface surrounding the singularity, and the gravity of the object is such that once anything enters this surface, it is trapped forever. Not even light can escape the pull of the singularity once it crosses the event horizon. That is why, we cannot see the singularity at the heart of a black hole but only see points outside the event horizon. Hence, all the physics happening within the black hole’s event horizon is indeed blocked from the view of the observer.