Can we send a probe inside a black hole? And why are we so obsessed with the Milky Way? This and more in this episode of The Astroholic Explains!

Listen on Apple Podcast or on your favourite podcast player through Anchor.


Chris

Hello and welcome back to a brand new episode of The Astroholic, I am Chris!

Alfredo

And I am Alfredo, the Astroholic

Chris

Let’s dive straight into some brand new questions from a couple of our listeners.

Alfredo

Fantastic. Let’s dive in!

Chris

The first question comes from @Paulieblogger on Twitter, who asks: can you send something into a black hole like a camera? Or would it disintegrate? It’s probably a stupid question, he then adds.

Alfredo

Okay, first of all, no such thing as a stupid question. Because you clearly are curious about this. You clearly want to know. And it doesn’t matter if it’s something that is obvious to me or to any other or even if it’s something that is super common, and a lot of people know and this is definitely not it. So if you’re curious, you should never feel bad for asking questions. And if somebody makes you feel bad for asking a question, let me know. And I’m going to go and beat them up.

 

Chris

The Astroholic is not advocating violence.

 

Alfredo

Okay, let me know. I’m gonna go meet them and I will say something.

 

Chris

I will have stern words with them.

 

Alfredo

Now I’m just gonna say something clever and devastating.

 

Chris

Brilliant.

 

Alfredo

No violence. So, no, you cannot throw anything into a black hole. It will disintegrate. But I think what is very interesting is how. How can we work out what’s in a black hole? Could we build something that might tell us something? Yes & no. So we need to understand just how enormously dramatic black holes are. So let’s start by approaching a black hole. The gravity around the black hole becomes so intense that even a person will start feeling, and let’s assume you’re jumping in feet first, the gravity on your feet from the black hole would be different from the gravity in your head. And as you get closer and closer to the black hole, you will start getting stretched.

 

Chris

Physically stretched?

 

Alfredo

Physically stretched!

 

Chris

Wow!

 

Alfredo

This is a process called spaghettification.

 

Chris

Did an Italian come up with this?

 

Alfredo

No, but there’s a lot of pasta related terms in space.

 

Chris

I’ve heard of noodles, space noodles,

 

Alfredo

Space noodles, there is nuclear pasta. There’s a lot! It’s just that Italians are popular.

 

Chris

Like pasta.

 

Alfredo

Yes. It’s not our fault that everyone loves us. So you’re being stretched and eventually you stretch so much that even the molecules in your body are broken down. You’re just a big cloud of hot plasma, and then you’re spiraling into the black hole. So far, there’s no material that can survive that.

I think we just got some potential first evidence for a collision between a black hole and a neutron star. What’s inside the neutral star is this nuclear pasta that I mentioned. This is probably the densest, most incredible material in the universe. And we don’t think anything like that survives unscathed, I think some will be thrown out and lose those properties. The rest will be sucked in by the black hole. There is nothing that we can build, as far as we can tell, that can survive the encounter with a black hole.

 

Chris

Woooah, okay!

 

Alfredo

How do we know about what’s inside?

 

Chris

Maths, isn’t it?

 

Alfredo

It is Maths!

 

Chris

My old nemesis.

 

Alfredo

Well, there is maths, there’s biology, there’s physics…

 

Chris

I’ve had many enemies!

 

Alfredo

Yeah, you’ve made many enemies in your school years. Thanks to the power of maths, we can sort of work out what the properties inside the black hole should be. And it still becomes complicated because black holes are surrounded by what we call the event horizon. beyond that point, nothing can escape. Not even light because beyond that point, the escape velocity that something should have to escape is larger than the speed of light.

 

Chris

I know something that couldn’t escape… love. [laughs]

 

Alfredo

No.

 

Chris

Oh, Interstellar was wrong?

 

Alfredo

Interstellar was wrong! But now there is an interesting thing since you mentioned love. So let’s assume, let’s go back, you jumping in! You know what you’re gonna experience dramatic forces and all of trauma and then you will be turned into plasma. And that’s it.

 

Chris

Typical Saturday!

 

Alfredo

Typical Saturday! But if I have a telescope and looking at you, I will see the light emitted by you getting to lower lower wavelengths, the redshift that we mentioned a few episodes back..

 

Chris

I remember

 

Alfredo

and that light that it will be there till the end of the universe.

 

Chris

So, there would be an imprint of me dying in space for eternity

 

Alfredo

But I can always look up at that.. awwwww

 

Chris

You can look at a photo!

 

Alfredo

Awwwwwwwww

 

Chris

No, it’s not cute. It’s devastating!

 

Alfredo

Okay, well, you said love.. So no, nothing escapes black holes: not light, not love.

 

Chris

Not me apparently!

 

Alfredo

And not you. So where were we with the question though?

 

Chris

I can’t remember!

 

Alfredo

No, me neither.

 

Chris

Maths!

 

Alfredo

Yes, the power of maths. So everything we know is through maths. And there is this barrier that stops us from actually physically seeing inside. The ways we’ve been sort of peeking through are pretty much the limits of our understanding of physics. One is gravitational waves we mentioned, they tell us quite a bit about the properties of black holes, when black holes merge and how the gravitational waves are emitted. And that’s just by having very very good theoretical ideas of what gravitational waves should look like. Another approach is something called Hawking radiation. So Stephen Hawking predicted that black holes..

 

Chris

They are hairy.

 

Alfredo

Yes, they’re hairy. Yes. Can you remember that?

 

Chris

I just said it. [laughs] So I remember there was a picture of one and it just looked like obviously, the stereotypical image of a black hole was just a big black circle. But the edge of it was all fuzzy and hairy.

 

Alfredo

Yes, the edges of it are all fuzzy and hairy. So, one big problem in physics is that general relativity and quantum mechanics don’t work quite well together. So generally, theory tells us that when something crosses, the event horizon is gone forever because nothing can escape the speed of light, and all information at the most can move at the speed of light. Quantum mechanics is telling us that the information of any system can change but it cannot just disappear. So suddenly black holes in quantum mechanics are changing the entire properties of the universe every time they eat something, and so they are constantly changing the properties of the universe. That doesn’t sit well. So one idea suggested by Stephen Hawking was that, over time, black holes can emit radiation. And this happens because at the edge on the event horizon, you can form particles, and you can form particles in any bit of the universe. So, you get some energy and that energy turns into a particle and an antiparticle, and then those two, the particle/antiparticle mix again, and they disappear. So they create and destroy, create and destroy

 

Chris

Over and over again over and over.

 

Alfredo

But at the edge of the event horizon when that happens, one particle is taken in and the other one escapes out

 

Chris

One in one out policy!

 

Alfredo

Yeah, but by escaping out, you’re taking away some of the energy.

 

Chris

So some energy does escape from a black hole?

 

Alfredo

Yes, because of that, yeah. And the idea was the black holes are a little bit hairy. So with that as well, we can sort of try to work out some of the properties. We have some very good theoretical ideas, but the finer details of what black holes are, like, still eludes us. So it’s a work in progress. But I’m very grateful for this question because I think Black holes are extremely, extremely fascinating. They are absolutely mind-blowing, and I could be talking for hours about them.

 

Chris

Maybe we’ll revisit the topic next season. On to our next question. Today’s second question comes from @JamesSPiperPhotography on Instagram, who asks, Will my addiction of the Milky Way ever go away?

 

Alfredo

Based on your gorgeous picture of the Milky Way, I really hope not. But in general, I think it’s something that fascinates everyone. Why? Why do we put so much belief and fascination and so much of our culture based on the stars and this strip of light across the sky?

 

Chris

Primordial culture, I guess?

 

Alfredo

It’s everything for us. Not everything in the universe, just tiny little dot in the universe, but it’s our tiny little dot in the universe. And seriously, if you’re a city dweller, like we are now, go into the countryside. Look up on a clear night sky and you’ll see it and it is breathtaking. And you looking at one hundred billion stars, and you’re looking towards a supermassive black hole that weighs 4.6 million times our Sun, you’re looking at star systems, planets, comets, nebulae all in our corner of the universe. I sincerely hope that this obsession, this addiction as you call it, it never goes away for you or for anyone else, and I think it’s so good to see… We know people that are doing great panoramas with gorgeous celestial phenomena from Northern Lights to meteor showers, to the occasional comets. We have panoramas with the Milky Way. And I’m not just talking about professional observatories, there is a huge amount of people that just are so passionate. It’s just fantastic. I always argue that astronomy is always been the oldest science, because we were, from our ancestral time, always looking up in the sky! Calendars were devised based on space. So I think this is why I enjoy so much talking about astronomy. Because it’s so important, so crucial, so fundamental to human culture. And I think people that take pictures and make videos, animations, it’s making all those faraway points of light, more real, more tangible. And sometimes, because we are in cities full of lives, we forget to look up and see the stars.

 

Chris

That was very beautiful.

 

Alfredo

Yeah, I could have been a poet in another life

 

Chris

It’s good and it’s important. And I think you hit the nail on the head. I don’t think anyone’s addiction to the Milky Way will vanish because, throughout human history, it never has.

 

Alfredo

Yeah. And although light pollution is a problem… I like to believe that it’s, again, the usual disclaimer, if we survive the climate crisis, we might get better at finding a solution to make the night sky even in cities more authentic.

 

Chris

I miss the stars.

 

Alfredo

Well, we’ll take you out of London soon enough.

Chris

Awesome. Thank you very much for answering our questions today. I hope you had a great time.

Alfredo

My pleasure, as always!

Chris

Well everyone listening, join us next time for the season finale of The Astroholic Explains

Alfredo

The season finale?

Chris

The Season finale. And guess what? I have something different planned. We are having a guest! [Dramatic Jingle]. See you next time!

Alfredo

See you next time!

Image Credit: The Event Horizon Collaboration