Darkness Visible: Shedding New Light on Black Holes
World Science Festival・89 minutes read
Black holes are extreme objects in the universe, akin to dividing by zero mathematically, with escape velocity on Earth at 11.2 km/s. Research aims to test Einstein's theory of gravity at the black hole's edge, analyzing data from the Event Horizon Telescope for release in early 2019.
Insights
- Einstein never actually said that black holes occur when God divides by zero, debunking a popular misattribution.
- Escape velocity is the speed needed for an object to break free from a planet's gravitational pull, varying based on the planet's mass.
- Research using the Event Horizon Telescope aims to challenge Einstein's theory of general relativity at the edge of a black hole, necessitating meticulous data analysis and calibration for publication.
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Recent questions
What is escape velocity?
The escape velocity is the speed required for an object to break free from a planet's gravitational pull. On Earth, this velocity is approximately 11.2 km/s. The escape velocity increases with the mass of the planet, making it harder for objects to overcome gravity and leave the planet's surface.
Who coined the term "black hole"?
The term "black hole" was coined by John Wheeler at the Goddard Institute of Space Studies. It refers to extreme physical objects in the universe where gravity is so intense that even light cannot escape beyond the event horizon, rendering them invisible or "black."
How are black holes observed?
Black holes are observed using various methods, including tracking stars' motion to confirm their presence at the galaxy's center. Radio waves are used to study their effects on the environment, revealing light orbits around the black hole and its silhouette. The Event Horizon Telescope combines data from multiple radio telescopes worldwide to create a virtual telescope the size of the Earth, capturing the most precise images of black holes.
What is the significance of gravitational waves?
Gravitational waves, predicted by Einstein's theory of general relativity, were confirmed in 2015 by the LIGO scientific collaboration. These waves are ripples in space-time caused by extreme cosmic events like black hole collisions. They provide a new way to observe the universe and test theories of gravity in extreme environments.
What is the information puzzle in black holes?
The information puzzle in black holes arises from the loss of information when a black hole evaporates, leading to uncertainty about the original data. This dilemma has prompted reevaluations of quantum mechanics and theories about where information is stored in black holes. Resolving this puzzle is crucial for understanding the nature of black holes and potentially the origins of the universe.
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Summary
00:00
"Black Holes: Gravity's Dark Mysteries Explored"
- Einstein is often misquoted as saying black holes occur when God divides by zero, although he never actually said this.
- Black holes are extreme physical objects in the universe, akin to dividing by zero mathematically.
- Escape velocity is the speed required for an object to escape a planet's gravitational pull.
- Escape velocity on Earth is approximately 11.2 km/s.
- Escape velocity increases with the mass of a planet.
- John Michell in the 1700s theorized about stars so massive that light couldn't escape, leading to dark stars.
- Einstein's general theory of relativity redefined gravity as warps in space-time.
- Karl Schwarzschild, inspired by Einstein's theory, calculated that extreme mass could create objects where even light couldn't escape, forming black holes.
- The term "black hole" was coined by John Wheeler at the Goddard Institute of Space Studies.
- Black holes distort space-time so severely that light cannot escape beyond the event horizon, rendering them black.
16:34
"Exploring Milky Way's Supermassive Black Hole"
- Teapot pours into the center of the galaxy, visible in the night sky as the Milky Way, using infrared technology to see stars at the galaxy's center.
- Star named so2 orbits the galaxy's center every 16 years, indicating a mass 4 million times that of the Sun in a small region.
- Research has increased dark matter density by ten million times, supporting the existence of supermassive black holes.
- Tracking stars' motion confirms the presence of a black hole at the galaxy's center, challenging Einstein's theory of general relativity.
- Project spans 25 years, observing stars moving at three million miles per hour, with technology advancements enabling more sophisticated work.
- Three-dimensional animation displays stars near the black hole, with observations inconsistent with predictions, leading to further exploration.
- Radio waves used to study black holes' effects on their environment, revealing light orbits around the black hole and its silhouette.
- Event Horizon Telescope combines data from multiple radio telescopes worldwide to create a virtual telescope the size of the Earth.
- Data from the Event Horizon Telescope, including the most precise image of a black hole, is being analyzed for release in early 2019.
- Research aims to test Einstein's theory of gravity at the black hole's edge, requiring meticulous data calibration and analysis before publication.
31:14
"Observing Sagittarius A: Black Hole Exploration"
- Telescope systems are operational, focused on observing Sagittarius A, the supermassive black hole in the galaxy's center.
- Teams venture to extreme locations like the South Pole, extinct volcanoes, Hawaii, and Chile for data collection.
- Data is stored on hard disks, flown back for processing on supercomputers, mimicking light bouncing off a parabola.
- The process involves capturing data using the Event Horizon Telescope technique, requiring patience due to delayed gratification.
- Simulations predict the appearance of the black hole's magnetic field and synchrotron emission.
- Radio waves are crucial for observing the black hole, needing to penetrate Earth's atmosphere and the galactic center's distance.
- The Earth's size is ideal for capturing radio waves with a wavelength of one millimeter, providing a resolution for imaging Sagittarius A.
- Testing Einstein's theories at the black hole's edge is a significant endeavor, respecting his intellect while aiming to verify his theories.
- The possibility of finding deviations from general relativity is considered, with a focus on testing and verifying theories.
- Gravitational waves, predicted by Einstein's theory, were initially doubted but later confirmed, leading to the development of the LIGO facility for their detection.
46:58
"Detecting Gravitational Waves: Mirrors, Collisions, Discoveries"
- Interference pattern of laser light used to detect motion of mirrors due to gravitational waves affecting space and time.
- Shaking measured by atomic distances, smaller than one thousandth of a nucleus, over a four-kilometer scale.
- Two detectors built in Louisiana and Washington to confirm gravitational wave detection independently.
- First detection of gravitational waves achieved in 2015 by LIGO scientific collaboration.
- Two black holes, over a billion light years away, detected colliding and emitting gravitational waves.
- Black holes merged into a single entity, emitting gravitational waves for 0.2 seconds.
- Gravitational wave energy output during collision equaled 50 times the energy of all stars in the observable universe.
- Gravitational waves detected in a frequency range of 20 to 700 Hertz, lasting 0.2 seconds.
- Data from detectors analyzed to determine masses of black holes and distance of collision.
- Subsequent detections of black hole collisions and neutron star collisions have expanded understanding of gravitational waves.
01:06:39
"Neutron star collisions reveal gold formation"
- The signal on the screen lasts about 30 seconds, but data extracted shows it lasted 140 seconds, indicating a longer event.
- The masses involved in the event were smaller, around 1.5 solar masses compared to 30 solar masses.
- The lower the mass, the longer the signal duration in such events.
- The third detector was less sensitive and located in a less favorable position, hence not showing the same signal.
- Unlike black hole mergers, neutron star collisions produce a variety of electromagnetic waves.
- Neutron star collisions confirmed the origin of gamma-ray bursts, previously hypothesized.
- The collision of two neutron stars led to the formation of heavy elements like gold and platinum.
- The event on August 17th provided experimental proof of gold formation in neutron star collisions.
- Gravitational wave observations aim to test Einstein's general relativity in extreme environments.
- The relationship between entropy and the area of a black hole's event horizon suggests a connection between information loss and the growth of the black hole's area.
01:24:07
"Black Hole Information Storage and Entropy"
- Information in a black hole is proportional to its area, with each element representing one square, akin to Planck areas of the Planck length.
- The size of these squares is around 10 to the minus 33 centimeters, with the event horizon's entropy determined by the number of squares present.
- Adding a particle carrying one unit of entropy to a black hole causes it to grow by one square, showcasing a consistent way to understand black holes.
- The combination of quantum theory and Einstein's theory in the early to mid-1970s led to the understanding of black hole entropy being linked to its area.
- Hawking's argument revealed a discrepancy between the information in a black hole and its featureless horizon, suggesting a need to locate where the information is stored.
- String theory combines relativity and quantum theory, proposing entities like strings or membranes as fundamental matter components.
- Initially, string theory suggested nine spatial dimensions, with six being tiny and hidden, but these extra dimensions played a crucial role in resolving black hole information storage issues.
- Wrapping strings or membranes around these extra dimensions creates a warped space resembling a black hole, accounting for the black hole's entropy.
- String theory computations aligned with Hawking's entropy predictions, offering a mathematical basis for understanding black hole structure.
- Hawking radiation involves particles created near a black hole's event horizon, with one particle escaping as radiation while the other falls in, leading to the black hole's eventual disappearance and the mystery of information loss.
01:39:46
"Black Hole Information Puzzle and Singularity"
- The information puzzle in black holes arises from the loss of information when a black hole evaporates, leading to uncertainty about the original data, like a dice roll.
- Initially, Stephen Hawking believed information couldn't escape black holes, prompting a reevaluation of quantum mechanics, but later changed his stance due to advancements in holography.
- Mathematical proofs in string theory suggest information should escape black holes, but the exact mechanism remains a mystery, with gradual radiation release being a potential explanation.
- The singularity at the center of black holes is a mathematical concept indicating a breakdown in our understanding, with no physical significance, and exploring it is crucial for comprehending black holes and potentially the origins of the universe.
- Time inside a black hole changes as one approaches the singularity, which could represent the end of time or the birth of a new universe, highlighting the importance of resolving the singularity issue for a deeper understanding of black holes and the universe's origins.
