Myth-busting: Are black holes really holes?

Chris Smith asked our panel of experts to de-bunk some suspicious sounding science. Chris was joined by marine biologist, Kate Feller and geneticist, Patrick Short, from the Univeristy of Cambridge. Also in the studio was science journalist Phillip Broadwith from the Royal Society of Chemistry and Astrophysicist, Matt Middleton, from Southampton University.

Kate - A lot of times, like at museums or in toy stores, they’ll have these compound eye glasses so you could see like a fly, because flies don’t have eyes that are like ours, they’re made up of thousands of these little facets, and so theoretically you can put on these glasses and you can see like a fly. But that is totally wrong because the way that these glasses work is they multiply the image you’re seeing into just thousands of the same image over, and over, and over again and so it looks really crazy.

But really, a compound eye works where each facet focuses on a specific point in space and then they all get assembled like a pixel in an image. So they just have a lower resolution image of the world than say we do because our eyes are just different.

Chris - Don’t astronomers do a similar thing with telescopes, Matt, they have telescopes that have individual little facets that can then take a miniature snapshot of a part of space that they’re looking at and then they reassemble the whole thing into a big picture?

Matt - Essentially, what they’re doing there is they make these new reflecting dishes out of all these segments and they control those very, very carefully. So they’re not really looking at a single thing, they’re having to work together in unison to be able to focus on something, but the ability of these new instruments is absolutely phenomenal. You have all these little micro motions on these mirrors to create an absolutely stunning image, even if the weather is absolutely terrible.

Chris - You can manipulate each of the individual facets and you can adapt what they’re seeing to the conditions?

Matt - Absolutely. Adaptive optics, that’s what it’s called.

Chris - It says that your choice of myth is that black holes aren’t holes… I’m disappointed

Matt - Are you genuinely, Chris?

Chris - A little bit because we all like to think they’re some sort of giant vacuum cleaner in space that’s drawing everything in, but you’re saying that’s not true.

Matt - You can throw some repugnant people in there. The idea of black holes, the actual term is kind of anecdotal, but it was actually coined during a lecture. Before you talk about a black hole you also have to take a step back and remind yourself what a black hole actually is. Most people who do anything with astronomy will say: okay, it’s the end of a star’s lifetime. A massive star’s collapsed down and there’s no more forces to prevent that core collapsing so it’s going to go all the way down. It’s going to essentially go down to an infinitesimal point containing all the mass.

The reality is you can make a black hole out of anything. You can make a black hole out of a pen, you can make a black hole out of Chris, which I highly recommend. All you have to do is compress him down incredibly small so that he actually sits inside what we call the event horizon. When you go beyond the event horizon, not even light can escape from that body. So if you go near that event horizon, you won’t necessarily be torn apart - it depends on the size of the black hole, but you are going one way and one way only, and that’s towards the singularity. And that is a point which is so small, we don’t yet have an idea of how to describe it, we need something called quantum gravity.

There is one caveat, if the black hole is spinning you don’t get a singularity you have something called a ringularity. There’s these ideas that maybe we can manipulate those and create wormholes and then maybe Chris, you’ll finally have your hole.

Chris - But one thing that is often trotted out is that the centre of galaxies, like our Milky Way galaxy, there is a supermassive black hole and people say it’s about the size of Neptune or something or maybe a bit bigger out to the size of Neptune orbits, that kind of things. So it’s not literally a single point, there is something that’s quite large sitting there. It has physical dimension.

Matt - What people normally talk about is the size of the event horizon. We consider that to be the surface when in reality it isn’t. The definition starts blurring when we talk about black holes but that’s what we normally discuss, we talk about the size of the event horizon.

What’s remarkable is that galaxies and the supermassive black holes grew together, so something which is so small interacted with something which is billions and billions of times bigger. I think that’s amazing, so it tells you that galaxies and the black hole had to know about each other, and that is phenomenal.

Chris - Warps your mind as well as space time, doesn’t it?

Matt - A little bit.

Chris - Patrick; what’s your choice of myth?

Patrick - Everybody knows about the risk of older mothers having children, but I think the thing that’s not talked about enough is the risk of older fathers. I think we have all these - about egg freezing - we have all these societal norms that tacitly punish women for having children when they’re older. But actually, the father’s sperm is constantly multiplying, and every time it multiplies it makes mistakes and introduces mutations and so the older a father becomes, the more likely they are to have children with problems as well.

Chris - Well the Rolling Stones are doing all right, aren’t they, with the combined age between them of 7 trillion years or so? I can’t remember what it is now but  they’re all pretty ancient; they’re doing okay.

Patrick - They’re not doing too bad. It’s about twice the risk or something from age 20 to 40 for men and then it starts getting worse and worse after that, but it’s just a role of the dice every time.

Chris - Matt, don’t get us done for libel…

Matt - Right. Remember that Mick Jagger’s trousers are so tight I don’t think he’s got any sperm left.

Chris - I think we’d better phone our lawyer. Kate?

Kate - Do they just negate the effects of being old men by having children with younger women?

Patrick - Yeah, that’s a really good point actually. It takes two to tango so maybe that’s the Rolling Stone’s secret.

Kate - So maybe that’s what women should be doing?

Patrick - Finding themselves a nice 25 year old man… yeah.

Chris - Let’s talk about chemistry. Phillip?

Phillip - My choice of myth is that chemicals that are made by plants and animals are somehow different to exactly the same chemicals if they’re made in a lab. If you’re talking about an absolutely pure substance there is absolutely no difference between the two. If you’re talking about having a real life thing it’s very difficult to get very pure things.

So if you were thinking about a chemical that you’ve isolated from a plant or an animal versus one that you’ve synthesised in a lab and not purified very well, then there would be differences between them because there’d be differences in the impurities in those things. But the actual chemicals themselves… no difference at all.

Chris - So when we talk about something being ‘natural,’ actually it’s just stuffed full of other stuff that we didn’t know was in there, or we can’t control the provenance of that? But something that comes out of a lab you actually have a better chance really of controlling the provenance. In fact, I’d rather have the lab version.

Phillip - Yeah, potentially. And that’s the other flip side of that is that people have this perception that a natural chemical is somehow better for you than one from a lab, but strychnine is a natural chemical.

Chris - So is cyanide, yeah.

Phillip - All of the poisons are natural things. That’s also another myth.