The Secret World Of Black Holes - Dr Becky Smethurst

TL;DR

Black holes are not actually holes but dense, massive objects that emit powerful gravity and can trap light. They are highly misunderstood and could have been better named.

Transcript

people ask me questions like what's on the other side of a black hole which doesn't make any sense when you realize that black holes aren't holes they are 3D objects that were one stars that have just been crushed down until they are so so dense that the gravity is so strong that nothing can escape from them anymore not even light what is your prob... Read More

Key Insights

• 🕳️ Black holes are not holes, but dense objects created from the collapse of stars.
• 🖤 The name "black hole" has caused misconceptions, as black holes can emit bright light due to gas spiraling into them.
• 🖤 The term "black hole" originated from a comparison to the infamous Black Hole of Calcutta prison cell.
• ✴️ Black holes have an event horizon or Schwarzschild radius, which is the point of no return where nothing can escape.
• ✴️ Black holes can spin and retain their spin from their stellar or neutron star progenitors.
• ✴️ Supermassive black holes can outshine all the stars in their galaxies and were initially mistaken for quasars.
• 🖤 Black hole studies are still relatively new and much remains unknown, including the nature of matter inside black holes.
• ⬛ The size of a black hole is directly related to its mass, with larger black holes having larger event horizons.

Questions & Answers

Q: What is a black hole?

A black hole is a 3D object formed from the collapse of a star, with immense gravity that traps anything, including light, from escaping.

Q: Why are black holes called "black holes"?

Black holes are not actually black, as they can emit bright light due to the gas spiraling into them. The name originated from the physicist Robert Dickey's comparison to the Black Hole of Calcutta prison cell.

Q: Can anything escape from a black hole?

Nothing can escape from a black hole, including light, due to the tremendous gravity within it. Black holes are like prisons for light.

Q: How do black holes affect their surroundings?

Black holes can emit bright light as gas spirals into them and gets accelerated to high speeds by their gravity. Supermassive black holes can even outshine all the stars in their galaxies.

Q: Do black holes spin?

Yes, black holes can spin, as they retain the spin of the star or neutron star they formed from. Adding more matter to a black hole can also increase its spin.

Q: What happens when two black holes merge?

The merging of two black holes is still a topic of speculation and research. Gravitational waves emitted during the merger can be detected, but the specific details are yet to be fully understood.

Q: Can black holes lose their mass over time?

Black holes can potentially lose their mass over extremely long periods through a process called Hawking radiation, where they emit energy, but the time it would take for a black hole to evaporate is astronomically long.

Q: Are black holes responsible for holding galaxies together?

While black holes play a role in the dynamics of galaxies, they do not solely hold galaxies together. The majority of a galaxy's mass is made up of stars, gas, and dark matter, which contribute to the gravitational forces that keep them intact.

Summary & Key Takeaways

• Black holes are not holes but 3D objects formed from the collapse of stars, with gravity so strong that nothing can escape them, not even light.

• The name "black hole" has caused misconceptions, as black holes are not black and can actually emit bright light due to the gas spiraling into them.

• The term "black hole" originated from a physicist who compared the crush of matter in a black hole to the Black Hole of Calcutta prison cell.