On the hunt for black holes: what are they, and why should you avoid them?, by Dr Edward Bloomer

The penultimate main lecture of the season proved to be a very popular one, with the lecture hall packed and barely an empty seat in the house.

The evening commenced as ever with members’ images, but this time with a twist; a selection of artwork from the recent astro art workshop, where a variety of interpretations of the Orion Nebula were produced, was also on show.

Then it was on to the members’ talk, Data-driven Astronomy with Thomas Obitz, asking how amateurs can still contribute in the age of large all-sky surveying telescopes, and answering it by showing numerous data sources that are open to everyone to interpret and use. In the past, similar technology was available to professionals and amateurs alike, allowing the Carrington Event, for example, to be discovered by an amateur, but now the best opportunities for amateur discoveries are in open science. The presentation captured everyone’s interest, inspiring many of the audience to find out more about the topic and how they can get involved, either to contribute or just to enhance their own observations.

Alec hosting the evening, Thomas talking about Data-driven Astronomy, and Simon with our RMG AV team. Pictures by Mike Meynell, Amy Scammell and Bobby Manoo.

The main lecture, which brought so many members out, didn’t disappoint. Presented by ROG Astronomer Dr Ed Bloomer, everyone was eager to learn more about where the hunt for black holes has taken us, and also why we really should avoid going anywhere near them.

Dr Bloomer, whose work has included gravitational waves and colliding black holes, began by discussing what black holes are and pointed out that it is actually easier to say what they are not. They are not a hole or a tunnel, but can best be described as a region of influence where gravity is so strong not even light can escape.

Using a number of interesting analogies to make the subject accessible to everyone, the most memorable involving how many marshmallows can be crushed into a space before they become a singularity, several of the audience were left craving soft sweet treats as well as cosmological knowledge.

Dr Ed Bloomer, during his talk to the Flamsteed. Pictures by Mike Meynell and Amy Scammell.

We were also treated to a photo of a “smiling” black hole, where gravitational lensing allows us to see the light from its far side, and learnt how the light jets from the supermassive black hole at the centre of Galaxy M87 extend for 6,000 light years.

Black holes, which not so long ago were purely theoretical, can now be detected in a number of ways, including by direct imaging and by the discovery of distortions caused by gravitational waves.

Barely a spare seat in the house. Another packed Flamsteed lecture. Pictures by Bobby Manoo.

Then came the scary part: what happens when you fall into a black hole. Starting in a classical orbit, as you approach the speed of light, while being bombarded by X-rays, you would reach a point of no return. Whatever trajectory you took, every path would lead you into the black hole. Heading inwards, spaghettification would take place as tidal forces stretched you apart, while in the photon sphere light would be bent so much you could see the back of your own head.

Ed answers questions at the end of his talk, with Alec hosting the Q&A session. Pictures by Bobby Manoo.

Finally, Hawking radiation was discussed before Dr Bloomer answered several audience questions. After the conclusion of the lecture, lively discussion continued during a book signing in the foyer, with members eventually leaving, some to go and hunt out the nearest marshmallows.