Startalk Radio – Cosmic Queries – Black Hole Paradox with Matt O’Dowd

Intro

In this episode of Startalk Radio, host Neil deGrasse Tyson is joined by Matt O’Dowd, an expert in black holes, quasars, and gravitational lensing. They explore the fascinating world of black holes, the paradoxes surrounding them, and the potential for using gravitational lensing to observe distant objects. Matt O’Dowd is a teacher at Lehman College and a host and writer for the PBS Space Time YouTube channel.

Main Takeaways

Black Hole Paradox

• Black holes are hyper-dense regions where gravity is so strong that light can’t escape.
• Hawking radiation causes black holes to leak away their mass and energy, potentially allowing information to be reconstructed.
• Entropy, a measure of hidden information, is proportional to the surface area of a black hole.
• The interior of a volume can be encoded on its surface, leading to the idea that we are all two-dimensional holograms.

Time Dilation and Quasars

• Time dilation needs to be considered when studying future cosmic events and distant galaxies.
• Quasars, which are supermassive black holes, can provide insights into the structure of the universe.
• Relativistic time dilation slows down the process of gas spluttering from quasars.
• Time delays in flares of lensed quasars can reveal the path length difference around the object and help map the expansion history of the universe.

Big Rip and Dark Energy

• The big rip, a phenomenon that may occur if dark energy is more exotic, could affect black holes by stretching them out and removing their event horizon density.
• Expansion dilutes the energy density around black holes, making them evaporate less quickly.
• Gravitational lensing can be used to observe distant objects and reconstruct the structure of quasars.
• Measuring different path lengths in lensed quasars can help determine the rate of the universe’s acceleration.

Exoplanets and Celestial Objects

• The discovery of new celestial objects, including planets and substellar objects, is ongoing and exciting.
• Celestial objects are classified based on how they were formed and their relationship to stars.
• The solar gravitational lens mission, though challenging, offers the potential to study exoplanets using the Sun’s gravitational lensing effect.
• Scientists continue to be surprised by objects and findings in their research.

Summary

Black Hole Paradox

Black holes are incredibly dense regions where gravity is so strong that even light cannot escape. Stephen Hawking’s discovery of Hawking radiation suggests that black holes can emit energy and lose mass over time. This raises the question of whether information about what falls into a black hole can somehow be reconstructed from the information carried by Hawking radiation. The concept of entropy, which measures the amount of hidden information in a system, is closely related to the surface area of a black hole. This has led to the intriguing idea that the interior of the universe could be encoded on its surface, implying that we are all two-dimensional holograms.

Time Dilation and Quasars

When studying future cosmic events and distant galaxies, it is crucial to consider time dilation. Quasars, which are supermassive black holes, can provide valuable insights into the structure of the universe. Time dilation slows down the process of gas spluttering from quasars, making their observation and understanding more complex. However, time delays in flares of lensed quasars can reveal the path length difference around the object, helping scientists map the expansion history of the universe.

Big Rip and Dark Energy

The big rip is a hypothetical phenomenon that may occur if dark energy is more exotic than currently believed. It could potentially affect black holes by stretching them out and removing their event horizon density. However, expansion dilutes the energy density around black holes, making them evaporate less quickly. Gravitational lensing, a phenomenon that bends light around massive objects, can be used to observe distant objects and reconstruct the structure of quasars. By measuring different path lengths in lensed quasars, scientists can gain insights into the rate of the universe’s acceleration and the nature of dark energy.

Exoplanets and Celestial Objects

The ongoing discovery of celestial objects, including planets and substellar objects, continues to captivate scientists. These objects are classified based on their formation and relationship to stars. The solar gravitational lens mission, though challenging, offers the potential to study exoplanets using the Sun’s gravitational lensing effect. By placing a telescope in a specific area beyond Neptune, scientists can leverage the Sun’s gravitational field to magnify distant objects, including exoplanets. Despite the challenges posed by the Sun’s brightness, the mission is still being discussed and considered. Scientists also continue to be surprised by objects and findings in their research, further fueling their curiosity and exploration of the universe.

Conclusion

This episode of Startalk Radio with guest Matt O’Dowd delves into the fascinating world of black holes, quasars, and gravitational lensing. Exploring concepts such as the black hole paradox, time dilation, the big rip, and the discovery of celestial objects, the conversation offers a glimpse into the mysteries and complexities of the universe. The potential for using gravitational lensing to observe distant objects and the ongoing search for exoplanets add to the excitement and wonder of scientific exploration. As our understanding of the universe expands, so does our appreciation for the beauty and intricacy of its workings.