Most known black holes have been found by searching for the x-rays emitted when the invisible object pulls material off an orbiting companion star. Since no light can escape from a black hole, they can only be detected by indirect means. By studying this unicorn and other objects like it, researchers hope to get a clearer picture of what happens to stars in the final moments of their lives and why some of them collapse to become black holes while others leave behind dense stellar husks called neutron stars. Jayasinghe and his colleagues have dubbed the object the “unicorn,” in part because it is unique, and in part because it was found in the constellation Monoceros, named by ancient astronomers after the Greek word for unicorn. The finding “should create a push to find these systems.” The discovery “implies that there are many more that we might find if we increased the volume of space that we searched,” says Tharindu Jayasinghe, an astronomer at Ohio State University and lead author of a new paper detailing the discovery in the Monthly Notices of the Royal Astronomical Society. Now, astronomers have discovered a black hole with just three times the mass of the sun, making it one of the smallest found to date-and it happens to be the closest known black hole, at just 1,500 light-years from Earth. But until recently, they’ve seen no signs of small ones, and that’s presented a long-standing mystery in astrophysics.

They’ve found plenty of big and medium-size ones over the years-including a supermassive monster at the heart of our galaxy. Some recently observed effects provide some remarkable support for this CCC picture.How small can a black hole be? For several decades, astronomers have worked to answer this question by tallying the black holes in our corner of the universe. Yet, a deeper understanding of the special nature of the Big Bang is obtained from the perspective of conformal geometry, removing the distinction between “big” and “small, and whereby the Big-Bang singularity, unlike those in black holes, becomes non-singular, and can be regarded as the conformal continuation of a previous “cosmic aeon”, leading to the picture of conformal cyclic cosmology (CCC) according to which the entire universe consists of a succession of such cosmic aeons, each of whose big bang is the conformal continuation of the remote future of a previous aeon.

It is hard to see how any ordinary procedures of “quantization” of Einstein’s theory can resolve this contrasting singularity conundrum, Similar arguments (largely by Stephen Hawking) apply also to the “Big-Bang” picture of the origin of the universe, but whose singularity has a profound structural difference, resulting in the 2nd law of thermodynamics, whereby “randomness” in the universe increases with time. Such singularities are expected to lie deep within what we now call black holes. The “singularity theorems” of the 1960s demonstrated that large enough celestial bodies, or collections of such bodies, would, collapse gravitationally, to “singularities”, where the equations and assumptions of Einstein’s general relativity cannot be mathematically continued. Gresham College presents The Annual Sir Thomas Gresham Lecture 2022 with Sir Roger Penrose:

A journey into a black hole