Podcast Summary
Black hole: A region of space-time where light can't escape: Black holes are regions in space where gravity is so strong that not even light can escape, forming when massive stars collapse, creating an event horizon, the point of no return, and separating it from the rest of the universe
A black hole is an astronomical phenomenon where gravity is so strong that not even light can escape. It forms when a massive star collapses in on itself, creating a region of space-time called the event horizon, which marks the point of no return. Beyond this point, nothing, including light, can escape the immense gravitational pull. Black holes are not actual membranes but rather a region of space-time where the escape velocity equals the speed of light. Crossing the event horizon means entering an area where information cannot be transmitted out, effectively separating it from the rest of the universe. While black holes are often thought of as dense objects, for supermassive black holes, there is typically nothing present at the event horizon. The Event Horizon Telescope project aims to take the first real image of a black hole, which could provide valuable insights into the nature of these mysterious cosmic entities.
Black holes and the limits of our understanding: Black holes challenge our understanding of space and time, can't be navigated once crossed, and were initially thought impossible but are now considered real cosmic entities. Einstein's theory of general relativity advanced beyond his wildest dreams, leading to modern technology like GPS and satellite networks.
Black holes, with their event horizons, challenge our understanding of space and time. These cosmic phenomena can't be navigated once you cross their boundary, making them intriguing and mysterious. A world line represents an object's path through space and time. However, if an object's final destination is within a black hole's event horizon, it can't be traced or communicated with from the outside. Our modern technology, like GPS units, requires adjustments for relativity to provide accurate location data. This demonstrates the significance of Einstein's theory of general relativity, which has advanced beyond his wildest dreams. He might have been surprised by our phones and their ability to pinpoint locations via satellite networks. Black holes, a theoretical concept during Einstein's time, were initially thought to be impossible due to the immense forces required to form them. However, they are now considered real cosmic entities. The first solution for a black hole was discovered in the 1960s, and the term "black hole" was coined around that time. Despite his intellectual brilliance, even Einstein couldn't have foreseen the technological advancements that would come to define our modern world. This highlights the importance of curiosity, exploration, and the pursuit of knowledge, as we continue to unravel the mysteries of the universe.
The gradual acceptance of black holes as a reality: Black holes, once considered impossible due to our understanding of matter's density, are now accepted as the end state of massive stars. They can evaporate naturally over time through Hawking radiation.
The belief in the existence of black holes was a gradual process that took decades due to the previous understanding that matter couldn't be much denser than water. This belief was challenged when scientists discovered white dwarves and neutron stars, which have extreme densities. Black holes, the end state of massive stars, were then considered a real possibility. However, understanding the nuclear physics behind black hole formation required advanced knowledge, which was largely gained through research on nuclear weapons. As for the question of whether a black hole can be destroyed, it can evaporate naturally over billions of years due to Hawking radiation, where particle-antiparticle pairs are produced at the event horizon and one particle falls in while the other escapes.
Black holes cannot be seen directly, only their shadows and effects can be observed: Black holes, though bright, cannot be seen directly due to their event horizons. Only their shadows and effects on surrounding matter are observable.
Black holes, despite being some of the brightest objects we see in the sky, cannot be seen directly due to the fact that all the action happens within their event horizon and light cannot escape. Instead, we see the shadow they cast and the gas and dust being attracted to them, which heats up and emits intense light. It's important to note that creating a black hole the size of an asteroid would be impossible, as they would be too small and would collapse into the center of the Earth. The Large Hadron Collider, which was once feared to create micro black holes, has not produced any evidence of their existence. Black holes are not terrorizing entities, but rather fascinating phenomena that continue to intrigue scientists.
Observing the shadow of a black hole: The Event Horizon Telescope's observation of a black hole's shadow reveals more about these mysterious celestial bodies, bringing us closer to understanding them.
While black holes are known for absorbing light and appearing unseeable, they actually cast a shadow due to the bright matter surrounding them. This shadow can be observed using powerful telescopes like the Event Horizon Telescope. The nearest known black hole is only a few tens of light years away from us, but to see its shadow, we would need to be much closer, possibly within the orbit of Mercury. The Milky Way galaxy contains about a billion stars, many of which will eventually become black holes. The black hole at the center of the Milky Way, which is about 25,000 light years away, is one of the few that we can hope to observe with current astronomical instruments. The Event Horizon Telescope is a project dedicated to observing the shadow of a black hole, and its successful observations in 2019 have brought us closer to understanding these mysterious celestial bodies.
Observing Black Holes with the Event Horizon Telescope: The Event Horizon Telescope allows us to observe black holes' shadows and event horizons, despite their small size on the sky, making astronomical discoveries possible.
Black holes, though small in size, can be observed through large telescopes like the Event Horizon Telescope, which synchronizes radio dishes worldwide to create a virtual Earth-sized dish. This telescope allows us to study the shadows and event horizons of black holes, despite the fact that there's no "behind" to hide. For instance, we can't hide behind a black hole, and even stepping too close would mean being pulled in. Furthermore, observing a black hole is akin to trying to resolve a small object, such as a citrus fruit, on the moon. The shadow of a supermassassive black hole at the center of our galaxy, which is about 4 million times the mass of our sun, measures only about 50 microarcseconds on the sky. So, the next time you're at the moon, remember to bring a favorite citrus fruit for a potential astronomical discovery!
Black holes: Distant and Dynamically Important: Black holes are far from us, but they significantly influence star formation and offer unique opportunities for scientific discovery
Black holes, despite their massive size and immense gravity, are not an immediate danger to us. The largest one in our galaxy, located at its center, is about 25,000 light years away and we're falling into it very slowly. However, these cosmic giants are dynamically important, influencing the formation of stars. Two notable black holes, the one at the center of the Milky Way and the one in the Virgo galaxy, are potential targets for observation due to their size and brightness. The Milky Way's black hole, Sagittarius A*, is significant because it's a representative of most black holes in the universe. The one in the Virgo galaxy, on the other hand, is much brighter due to the jets of relativistic particles it emits. These black holes present unique opportunities for scientists to learn more about these mysterious phenomena, with the potential for observing their shadows or taking pictures of them. The discovery and study of black holes continue to expand our understanding of the universe.
New Discovery of X-ray Emissions in Our Galaxy's Center: Scientists found X-ray emissions from a shock wave reaching clouds near a black hole, but the expected 'fireworks' didn't occur due to the black hole's spin.
Scientists are observing the center of our galaxy and have discovered evidence of a burst of activity that occurred around 300 light years away, which is causing X-ray emissions. They believe this could be due to a shock wave from an earlier event reaching clouds in the area. This discovery has led to the study of a black hole 25,000 years in the past, and the possibility that a gas cloud falling into it was expected to cause "fireworks," but instead, it has been a "big dud." The explanation for this is that the black hole's spin plays a role in whether or not there would be visible effects when matter falls in. Additionally, there are ongoing debates about the potential impact of Hawking radiation on the shadow of the black hole as observed by the Event Horizon Telescope. Blair Jackson's question on Facebook about the possibility of the Big Bang being the birth of a black hole and us living within it was also discussed, with the consensus being that while it's an intriguing idea, it's not taken seriously by most scientists.
The Singularity in the Big Bang and Black Holes: Both the Big Bang and black holes may generate waves in spacetime, and black holes all appear the same once settled, while massless particles like neutrinos can travel at the speed of light and follow Einstein's E=mc^2 equation.
The concepts of the singularity in the big bang and in a black hole are surprisingly similar, and both may produce waves or "sounds" in the fabric of spacetime, even if not in the way we typically understand sound. Additionally, black holes, regardless of what is thrown into them, all look the same once they've settled down, making them an intriguing cosmic puzzle. Furthermore, anything with no mass, such as certain subatomic particles like neutrinos, can travel at the speed of light, and their energy can be described using Einstein's famous equation, E=mc^2, which represents the energy carried by an object as it moves through time. Stay tuned for more cosmic queries on StarTalk All Stars.
Taking the first picture of a black hole: Scientists aim to test Einstein's theories and study the dynamics of matter around a black hole by taking the first picture, focusing on the shadow predicted by Einstein's theories, using a global consortium of telescopes to fill in an Earth-sized telescope, and remaining optimistic about the success despite challenges.
Scientists, led by Shep Dohlman and the Event Horizon Telescope Project, are working towards taking the first picture of a black hole, specifically the one at the center of our galaxy. With initial observations starting in spring 2017, they aim to test Einstein's theories and study the dynamics of matter around the black hole. The shadow of the black hole, predicted by Einstein, will be the focus of the image. Although light orbits around a black hole, observations will be made slightly further out due to the last photon orbit and the extreme deformation of space-time. The global consortium, formed from humble beginnings with three telescopes, is now instrumenting telescopes around the world to fill in the Earth-sized telescope and make the image. Despite the challenges and potential for decades-long experiments, the team remains optimistic about the success of the first image in spring 2017.
First Image of a Black Hole with Event Horizon Telescope: Scientists plan to capture the first image of a black hole using the Event Horizon Telescope, combining world's largest telescopes and freezing light. Potential discoveries could challenge Einstein's theory or reveal new forms of gravity.
Scientists are working on a groundbreaking project, the Event Horizon Telescope, which aims to capture the first image of a black hole. Despite the uncertainty and potential for unexpected discoveries, the team is optimistic about success in 2017. They plan to use some of the world's largest telescopes and freeze light at unprecedented rates. There's a possibility of discovering something unexpected, which could challenge Einstein's theory of general relativity or reveal new forms of gravity. The team is aware of the challenges and the potential for the unknown, but they are excited about the possibilities. While the public can't build their own telescopes for this project, they can follow the progress and be part of the scientific discovery process.
The reconciliation of general relativity and quantum mechanics remains a mystery: Despite efforts to quantize the universe, our mathematical tools struggle due to gravity's nonlinearity and complex feedback effects. Possible solutions include viewing gravity as an emergent phenomenon.
The reconciliation of general relativity and quantum mechanics as one theory of everything remains a mystery in theoretical physics. While we have tried to quantize models of the universe, our current mathematical tools fail us due to gravity's nonlinearity and complex feedback effects. It's possible that gravity might not be a fundamental force but an illusion that emerges on large scales. Black holes, which have sharp gravitational gradients, do affect time, causing it to slow down near them. However, our understanding of black holes is primarily classical, and quantum physics plays a minimal role in their identification astrophysically.
Exploring Black Holes: Overcoming Earth's Atmosphere and Studying Collisions: Technological advancements enable us to observe black holes more closely, from mitigating Earth's atmosphere with orbiting telescopes to detecting gravitational waves from collisions
While mathematicians and scientists continue to study the quantum aspects of black holes using pen and paper, advancements in technology are allowing us to make significant strides in observing these phenomena. One major limitation in taking black hole pictures is the Earth's atmosphere, which can be mitigated by placing telescopes in orbit. For instance, the Event Horizon Telescope, which uses radio waves to observe black holes, is currently limited in size due to its terrestrial location. If we could put a telescope as big as the orbital size of the Earth in space, we could potentially capture more detailed images. Another intriguing aspect of black holes is their behavior when they collide. Contrary to popular belief, two black holes do not cancel each other out but instead merge, forming a larger black hole. Some of the mass is released as gravitational wave energy. The first detection of this phenomenon was made by LIGO in 2015, marking a major breakthrough in our understanding of black holes. In summary, the pursuit of knowledge about black holes continues to push the boundaries of technology and mathematics, offering fascinating insights into the mysteries of the universe. For more information, visit eventhorizontelescope.org and follow Matt Kirschenbaum on Twitter.
