It's time for another excellent episode of RTÉjr Radio's science show Let's Dive In. Here, your hosts Julie and Phil are joined by Allen Foster again to find out what would happen if we went into a black hole.

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Julie tells us more...

In November 2022 a group of astronomers told the world that they had discovered what they believe is the closest black hole to Earth. A mere 1600 light years away (that means, it takes light 1600 Earth-years to get from that black hole to Earth).

We're practically neighbours!

Which makes this question from 10 year old Harry rather topical: What happens if you get sucked into a black hole?

Before we dive into a black hole, let’s think about what a black hole is. It is a place in space and time where the gravity is so strong that even light cannot escape. Black holes are formed when enough stuff, or mass, comes together in a small space: this happens when a star is dying.

Before we answer Harry’s question, Allen Foster (who we spoke to for an episode about exploding stars), is a PhD student at Case Western Reserve University in Cleveland, USA, and he just spent his first season as a winterover at the South Pole Station in Antarctica.

He wanted to clarify something with us before we "dove into" blackholes. "The big misconception…of blackholes, is that they don’t suck you in. But if you happen to fall into it, then its gravity is so strong that you can’t escape."

Right, so now that’s cleared up.

"The answer for the most part is that we just don’t know exactly what would happen if you fall into a black hole… but we do know what happens if you were to be very close to a black hole," says Allen.

To help visualise how a black hole works, imagine space time is like a giant trampoline that all of the universe sits in, or on. And each "thing" in space, like a star or a galaxy, or a black hole, has mass. It’s made of stuff. The more massive it is, the more it dips into the spacetime trampoline.

Just like a real trampoline - try it at home if you can! (and be careful up there!!)

What you need:

  • Two or three people
  • A trampoline
  • A measuring device like measuring tape or long ruler
  • Scales large enough to weigh humans.

What you need to do:

  • Get person 1 to sit on the trampoline
  • Persons 2 and 3 to stand at the side of the trampoline and use the ruler to measure how deep the dip of the trampoline is
  • Repeat for persons 2 and 3
  • Weigh each person
  • See if there is a correlation between the depth of the dip and the weight of the people

Now llack holes are the most massive things in space. And so, when they sit on this space trampoline, they create a really, really, REALLY, big dip. And the bigger the black hole, the more the spacetime is bent.

OK, so what happens if you were to fall into this shute? When the gravitational force of a black hole is really strong, "You end up getting stretched apart when you go into there, spaghettified is what they call it," says Allen. Your feet would fall down the shute much faster than your head, so you get stretched out as you fall in.

To help visualise this: imagine that the black hole is like a waterfall, and imagine you’re Elastagirl from the Incredibles. And as you’re going towards the edge of the waterfall, your toes get stretched and then your feet get stretched until you get turned into a very long version of Elastagirl, like spaghetti Elastagirl.

Now if we’re diving into this metaphorical black hole pool, what would we find at the bottom? Tune into the episode to find out!

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AND read all the Let's Dive In articles with experiments to try at home HERE!