The EHT (Event Horizon Telescope) is a remarkable piece of technology that has allowed humans to detect black holes

The EHT is not just one telescope, but it's a network of radio telescopes spread across the world

They are strategically placed in order to create an earth-sized telescope through a technique called VLBI(Very long baseline interferometry)

This technique allows the telescopes to function in unison, increasing their effectiveness with greater resolution

The EHT specializes in observing radio wavelengths. This is because the accretion disks around black holes emit radio waves

The main component of a radio telescope is the parabolic dish antenna

The shape is designed to focus incoming radio waves onto a receiver located at the focal point

The larger the dish, the more details it is capable of detecting

The data observed by each telescope is then collected and put together to form high-quality images.

The EHT made an astonishing discovery of a supermassive black hole in 2019 at the center of galaxy M87, it was the first direct visual detection of a black hole

LIGO consists of two identical observatories, one located in Washington and one in Louisiana

Each of these observatories is spread by two identically long arms, in an L shape approximately 4 km in both directions

The main component of LIGO’s functionality is the use of laser light

This light is shot down each arm where it then meets a highly reflective mirror at the end and then continues to move throughout the structure

Black holes generate gravitational waves that cause stretching and compressions through spacetime

When these waves hit Earth, it changes the length that the light has to travel which is found by sensitive detectors.

These detectors are capable of measuring extremely small changes in length, even to a fraction of the diameter of a proton

To confirm the detection of a black hole, scientists at LIGO communicate with other scientists such as the ones at Virgo in Europe to ensure accuracy.

Black holes are important to learn more about as it causes a scientific clash between the theory of general relativity and quantum theory when analyzing the singularity and the event horizon. It is the key to understanding the universe as it is an existing matter that forces researchers to look deeping into the fundamental properties of space and time. 

Black holes begin to contradict scientists' basic knowledge of space and time when considering the center of a black hole, also called the singularity. Given Pernrose’s spacetime diagram of a black hole where time and space are not consistent throughout the black hole, scientists are able to deduce that the singularity is not an actual point and instead is a moment in time. 

The event horizon surrounds the black hole and is a point in space where time has completely stopped. Given the glow and temperature emitted from the event horizon, Steven Hawking considered quantum theory and quantum mechanics which provided the idea that within the event horizon, a pair of particles known as the entangled particles are on either side of the event horizon. One at the edge of the black hole while the other is not. There is a chance that that particle escapes the event horizon which would mean that the black hole will eventually get smaller and smaller. This also means that black holes have a lifespan. 

Once a black hole meets the end of its lifespan, all the matter sucked into the hole would have been broken down to particle form and escaped the event horizon. Given the law of conservation of information, there is theoretically a way for the objects that fell into the hole to be reconstructed. This is called the black hole information paradox as scientists originally believed that black holes erased information from the universe. 

By delving deeper into understanding black holes, scientists will be able to have a more solid understanding of gravity, space, and time. They must first understand the fundamental concepts of physics in order to advance in physics research. 

Planck Stars: 

Black holes are made of matter packed so tightly that gravity overwhelms all other forces 

Black hole are so extreme that they are the perfect place to test the limits of the rules of the universe 

Observing black holes allow us to better understand the nature of the universe

• We used the collisions of black hole to prove Einstein's theories about 

Black holes also have some distinct role to play in the formation of galaxies, including our own 

Black holes can help us understand a wide variety of topics including: 

• Understanding extreme physic and how stars and planets grow 

  • Some supermassive are active engine to easily swallow starts and through that spiraling electromagnetic field, super-heated gasses and materials known as Quasars are flung out 

  • This process can also tell us about the physics of these extreme environments, along with showing us the conditions under which galaxies, planets and stars are born grow and die 

• Understand how fast the universe is expands, linking back to how it initially evolved 

  • Holz and other scientists have used the collision of black holes to calculate how fast the universe is expanding, finding the Hubble constant 

    • The Hubble constant allows us to understand the past present and future behavior of the universe and the nature of dark matter and energy 

• Reconciling our major theories of the universe 

  • Black holes allow us to see the link between quantum mechanics and general reality, the laws for the smallest particles and the largest respectively 

  • Stephen Hawking theories that the laws of quantum mechanics suggest that black holes have a very tiny temperature, implying that some radiation is leaving the black hole which can further imply the loss of mass faster and faster over time until they inevitably explode, even if it takes trillions and trillions of years to happen

Scientists can’t directly observe black holes with telescopes that detect x-rays, light or any other forms of electromagnetic radiation

• Whereas we can infer the presence and location based on the effect of the black hole on the matter around them 

  • Ex. If a black hole passes through a cloud of interstellar matter it will  draw in into itself in a process known as accretion 

  • If this same scenario where to happen with a star, it would break apart and prduce heat as it accelerates toward the hole, emitting x-rays that radiate into space 

It is very hard to accurately detect the distance of black hole but there are some strategies used by scientists over time. 

In 2009, scientists accurately detected the distance of earth from a black hole using a parallax technique. A small group of researchers used information from the High Sensitivity Array to triangulate the distance to the black hole V404 Cyg. This technique has around a 50% chance of error as not all black holes have the same characteristics and qualities.

By looking for material and stuff that falls into a black hole, scientists are able to deduce that there is a black hole in that area. When being sucked into a black hole, the matter being consumed illuminates and rises in temperature which can be observed. This random occurrence for the material in space signifies something aggressively pulling that material towards them which can only be explained by black holes. We are able to deduct how far a material is from Earth as long as we can see it. 

By also observing the stars and matter around “empty” space, it may signify that there is a black hole. Due to a black hole’s gravitational pull, stars and other materials would orbit around it. To researchers collecting data, they would see these stars orbiting around what seems to be nothing. This would indicate a black hole is present.

Another way to detect black holes is to detect the gravitational ripples when they collide. From the signal of two black holes colliding, we are able to detect how large the holes were, how far away they were before colliding, and how fast they were traveling.  

The process of black hole formation begins when a star of an extremely large mass uses up its entire fuel supply and experiences a sudden loss of mass, causing the star to undergo a supernova. This results in the outer shell of the star being shed, leaving behind a remnant neutron star.

It is a common belief amongst Astronomers that the energy emitted from quasars has a limiting effect on the growth of galaxies.

One potential reason for this is that quasars create very intense and destructive winds that emit the equivalent energy of hundreds of solar masses each year. These winds sweep across their given galaxy, violently carrying away material needed to form new celestial bodies, this would in turn cause star birth to cease in the process, thereby limiting the growth of any given galaxy.

In order to properly assess whether or not the theory on these violent winds is true, NASA plans to use three-dimensional imaging spectroscopy, a function of the James Webb Telescope to draw relevant information on precisely how these quasar winds affect the galaxy they belong to.

For this experiment, NASA has selected three very bright quasars for two reasons. 

• First, these three quasars are noted to be some of the brightest known quasars at their respective distances. 

• Second, these three quasars have been confirmed to possess an outflow of material.

The final theory currently believed before anything can be confirmed, as this is the experiment that will hopefully provide a conclusive answer to the question, is that the outflow from powerful quasars prevents a galaxy from creating new stars and therefore growing the galaxy.

With enough mass, gravitational attraction within the matter itself overcomes all other forces and matter beings to collapse 

Then the matter itself keeps collapsing until it reaches singularity, becoming infinitely dense and is infinitely small 

• At this point, space-time starts to distort, then nothing can escape from the immediate region, not even light 

Karl Schwarzschild derived an equation for the radius of a black hole also known as an event horizon 

• Even though the center is simply a singularity, we say that it is a black hole, the size of the event horizon around it 

Once inside the black holes event horizon, the matter being absorbed will be torn apart into its smallest subatomic components and eventually be squeezed into the singularity 

Once the singularity accumulates more and more matter, the size of the black hole’s event horizons gets larger and larger 

Most believed that the matter in a black hole once consumed would be forever gone, whereas Steven Hawking believe that black holes could radiate energy away known as hawking radiation 

• The black holes eventually start to lose what they absorbed very slowly 

• This process is so incalculably slow that even if a small black hole was to go through this process is would take an unimaginably long time 

Black holes are normally objects that are incredibly difficult to view, as they even absorb light. However one method of detecting a black hole can be found due to an area of a black hole called the accretion disk, which is a ring of material surrounding the black hole. All the material in this disk is remnants of objects that the black hole has already absorbed.

• These accretion disks make black holes visible due to the fact that as the material making up the accretion disk moves closer and closer to the black hole, its speed continuously increases, creating friction and thereby heat, causing the disk to glow, and a shadow of the black hole is created and made visible.

As for the material that is fully absorbed into the black hole our current understanding of the interior of black holes dictates that once any form of material crosses the event horizon of a black hole, it is almost certainly lost forever. The only exception to this statement is a theory proposed by Steven Hawking that proposed escape from a black hole may be possible, but it would be a prolonged process

This leads to the survival of black holes, their survival is completely dependent on the amount of energy they contain, as black holes will perpetually shed their energy. The lifespan of a black hole can be compared to a timer, or better yet an hourglass. The sand plays the part of the energy the black hole possesses, and as the sand whittles down, so too does the life force of the black hole.

• Black holes absorb energy by consuming the gasses and stars and any material they can pull into their event horizon. This consumption allows them to restore their stores of energy, and thereby extend their timer before they begin to die. As long as a black hole can continue to consume material, therefore gaining energy, it will continue to live on and even expand. Both the accretion disks and the black holes themselves expand as they absorb more mass. Therefore when absorbing material, a black hole will not only extend its lifespan but also expand its size as well.

• The exact reasoning behind this is the process by which black holes do begin to die. Since black holes constantly shed their energy, they are thereby shedding their mass away, which means they begin to shrink bit by bit, meaning that their lifespan is solely dependent on how long they can hold out before shedding all their mass away. This means that as long as a black hole can retain its mass, and thereby size, it will be able to counteract the constant shrinking and stay alive.

Although even if black holes are constantly shedding energy and shrinking, it does not at all mean that any black holes will die any time soon. It is estimated that for a supermassive black hole, the one found at the center of many galaxies, it would take around 10¹⁰⁰ years to fully disappear. Black holes can continue resetting their timers for unfathomably long periods of time, their hourglass will not easily empty.

In conclusion, the amount of matter consumed by a black hole is directly proportional to its lifespan. The more mass consumed by a black hole, the more mass that black hole will possess, therefore taking that much longer to lose said mass, continuously cheating its death until there is no more surrounding mass to consume.

Allow us to explore fundamental physics

Potentially see back to the big bang

Scientists have found evidence of gravitational or ripples in the fabric of space-time 

Movement of black holes and other objects in space can create ripples in the universe called gravitational waves. 

On June 28, 2023 scientists announced the first evidence of a background of long-wavelength gravitational waves fills the cosmos 

These waves are created over long periods of time by supermassive black holes (up to 3 billions of times the mass of our sun) 

The sound of a gravitational wave is the same as hearing the hum of a large group of people talking at a party. 

The detection of these waves will help scientists better understand how gravitational waves are created and what happens to them as they spread the universe 

Could also be used to study supermassive black hole mergers 

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) was the organization that presented this recently discovered evidence in a series of papers published in the Astrophysical Journal Letters. 

This Organization has spent more than 15 years trying to collect high-quality data from ground-based radio telescopes

This discovery made from the NANOGrav complements the first-ever detection of gravitational waves in 2015 by LIGO 

The waves detected by LIGO were much shorter compared to the newer discovery and were from black holes only about 30 times the mass of our Sun. 

Now NASA is focusing on the ESA (European Space Agency)-led Laser Interferometer Space Antenna mission, a space based observatory that will detect gravitational waves that are in a wavelength range between the NANOGrav and LIGO ones. 

Quasars and galaxies directly affect each other, Galiaxies supply fuel to the black holes

• the quasar heat and disrupts the gas clouds in the galaxy 

• Athe blacnace between these two processes helps explain as to the holes seemas to always be about 1/200 the mass of the starts that surround the black hole 

Quaser have several reduced in numbers, billions of years agi they were far more common 

• Some believe that they mark an early state in the formation of galaxies 

• Quasars were more likely to be active when the universe was young and fuel for their accretion disk was more available 

The activity of quasar can be re triggered by a collision between two galaxies

• This collision provides more fuel to feed that black holes 

This is due Hawking radiation which was a concept developed by Stephen Hawking to explain the fact that black holes will eventually evaporate along with everything it swallowed in its lifetime

Black holes were thought to be completely black and could not be in equilibrium with thermal energy until Hawking found there to be radiation coming from a black hole during his research. The radiation will release energy and therefore shrink the black hole until nothing is left. Scientists originally thought that energy would be lost but Hawking concluded that the energy released cannot be used. He says it is similar to “burning an encyclopedia” where it originally had information but is now in a different state which cannot be converted back to its original form. 

Stephen Hawking combined quantum theory and general relativity to consider particles escaping the black hole. Using quantum theory that suggests that there are particle-antiparticle pairs, Hawking concluded that if these pairs were at the edge of the event horizon, there is a chance that the negative antiparticle will fall into the black hole while the other positive particle escapes into space. The loss of particles and energy will result in the slow but eventual evaporation of a black hole. 

• The escaped particle is what scientists call Hawking radiation 

• Black holes have a temperature, although only slightly higher than absolute 0. Hawking was able to show that the amount of energy/radiation a black hole is able to release is inversely proportional to the mass of the black hole. This means that the smaller the black hole, the more energy it is able to release and the quicker it will evaporate and also that the temperature emitted from the black hole is due to Hawking radiation. 

• Researchers were able to create a similar phenomena of smaller black holes in a lab which proved that radiation is constant and does not grow over time. Proving Hawking radiation to be true. 

Scientists have created a lab-grown black hole experiment to test on of Hawking’s most famous theories and it turns out it behaves just like his predictions 

The experiment was created by using a single-file chain of atoms to stimulate the event horizon of a black hole has added further evidence to the theory; stating that black holes give off a faint glow of radiation from virtual particles randomly forming into existence new their boundaries. 

Researchers also found that most of the photons (light particles) should be produced around the cosmic monsters’ edges. 

In 1974, Stephen Hawking's predicted that the extreme gravitational forces felt in the middle of black holes would create photons (light particles) into existence. 

Physicists are interested in Hawking’s prediction because it is made at the extreme boundary of physics’ two big theories; Einstein’s theory of general relativity (that describes the world of large objects) and quantum mechanics (which discusses the behaviors of the smallest particles) 

Detecting these hypothesized light directly is something astrophysicists are unlikely ever to achieve. Many posed challenges come in the way, for instance traveling to a black hole (the closest one being 1,566 light-years away from the Earth) and once individuals end up making it to a black hole then they will most probably end up getting immensely pulled by the gravitational pull. Additionally, these Hawking’s photons around black holes are thought to be really small 

In the absence of a real black hole, physicists have begun looking for Hawking radiation in experiments.

In 2021, researchers used a one-dimensional row of 8,000 super-cooled, laser-confined atoms of the element rubidium, to create virtual particles in the form of wave-like excitation's along the chain.  

Another experiment achieved a similar outcome by adjusting the electron movement between atoms, creating an artificial version of a black hole’s space-time warping event horizon 

When part of the chain crossed this stimulated horizon, researchers observed a temperature spike, mimicking the infrared radiation emitted around black holes 

The findings of these experiments indicate a potential relation between Hawking radiation and quantum entanglement (occurs between particles on either side of an event horizon) 

For the production of Hawking radiation, there needs to be a change in specific energy configurations of space-time 

Notably, the model used in the experiment critically lacked the powerful gravity distortions produced by a black hole. So the connection between the theory of quantum gravity and the potential occurrence of naturally-produced Hawking radiation are still unclear. 

Black holes form in the final moments of a massive star’s life 

They grow my consuming matter within their event horizon, where gravity is extremely strong 

Medium-mass black holes, known as stellar mass, can grow larger by consuming other black holes, especially during galaxy mergers 

Over time, they can evolve into supermassive black holes found at the centers of galaxies 

Ultra-massive black holes, exemplified by PKS 0745 in the Puppis constellation, are even larger than supermassive black holes 

NASA’s 2012 survey revealed that some of PKS 0745’s black holes are ten times more massive than previously thought 

Ultra-massive black holes can have masses between ten and forty billion times that of the Sun

They contain an unusually contain large amounts of hot gas, leading to diffuse x-ray emissions when consuming material 

Stellar-mass black holes range from four to ten solar masses, while supermassive ones can be hundreds of millions to a billion solar masses 

Ultra-massive black holes challenge previous expectations, raising questions about growth limits 

Yale University researchers found that the growth of the most massive black holes appears to stall after reaching about ten billion solar masses 

The reason for this slowdown may be related to the immense energy radiated by these ultra-massive black holes.

While the research suggests a limit to black hole growth, the discovery of ultra-massive black holes larger than expected raises the possibility that there might be no upper limit 

Astronomers are now reconsidering whether black holes continue growing indefinitely or if they self-destruct due to energy radiation. 

Like all neutron stars pulsars go through the same process at the start of their lives

The NANOGrav (North American Nanohertz Observatory for Gravitational Waves) is a ground-based radio telescope that specializes in low frequency gravitational waves, different from LIGO which is more of a laser-based piece of technology 

Magnetars are a type of neutron star with incredibly strong magnetic fields, the strongest observed in the universe 

Magnetars emit eruptive X-rays and gamma rays 

These are associated with bursts of intense radiation, likely due to the ultra-strong magnetic fields

Magnetars are believed to form the collapse of massive stars’ iron cores in core-collapse supernovae 

There are many challenges scientists faced in order to example the origin of magnetar magnetic fields

CEA Saclay and Max Planck institute for Astrophysics; describes the study’s approach to developing a detailed computer model explaining the creation of strong magnetic fields during the formation of rapidly rotating neutron stars 

The study also mentions the dynamo effect, where the strong internal convective mass flows during the newborn neutron star’s cooling strengthen pre-existing weak magnetic fields 

The simulation highlighted the use of supercomputer to simulate convection in a rapidly spinning neutron star 

The study finds that weak initial magnetic fields can be improved to extremely high values for sufficiently fast rotation periods 

The study’s results also provide insights into the formation of galactic magnetars and contribute to understanding powerful stellar explosions 

Additionally connects the study’s findings to the “millisecond magnetar” scenario, suggesting the rotational energy of a fast-rotating neutron star as an extra source of energy storage. 

Describes how a powerful magnetic field with two poles can move the rotating energy of the neutron star into the explosion 

The study’s results provide theoretical support for the millisecond magnetar scenario, addressing the main reason for extreme stellar events.

Black holes can only be detected by observing their effects on nearby matter and space 

Because of their enormous mass, black holes have extremely high gravity which pulls in surrounding material at rapid speed

• This speed causes the matter to become so incredibly hot that it emits x-rays 

• These x-rays help us use specialized telescopes to image the materials as they spiral into the black hole, revealing the black hole’s location 

  • This technique in used in NASA’s Chandra X-ray observatory 

• Other telescopes can measure the speed of the gas and start orbiting what they believe to be a black hole, then with these measurements, Scientists can determine the mass of the black hole 

  • This is used by NASA's Hubble telescope 

• These two telescope are also able to image the the effects of gravitational lenseing 

  • Gravitational lenseing is the bending of light that results from the gravitational pull of high mass objects like Galaxies and black holes 

Scientists making use of the James Web Telescope began to study a certain aspect of several different galaxies called the active galactic nucleus, which is meant to describe the supermassive black hole at the center of a galaxy. This process was conducted using a specialized observation tool called a “Medium-Resolution Spectrometer”, or MRS for short which in turn is a part of another observation tool called the “Mid-Infrared Instrument”, or MIRI for short. 

This specialized spectrometer utilizes another concept called integral field units, or IFUs for short, these units are a combination of both a camera and a spectrograph, a spectrograph being a specialized tool allowing scientists to discover properties of a material depending on how light interacts with it. This special field unit is used to provide the team working with the James Webb Telescope with a database of images of their goal, the features of a galactic core black hole.

• One featured use of IFUs is for scientists to collect large amounts of spectral data on a structure, this including measurements and even velocity.

Using the previously mentioned tools, the MRS of the MIRI, scientists are able to see through the clouds of dust that surround this core black hole and analyze the contents behind these clouds. What specifically is being measured during this viewing is emissions caused by the very hot gases surrounding the black hole, these gases become very bright as a result of being ionized by powerful winds and radiation emanating from the black hole. 

• The process of how these dust clouds come to be is due to the black hole’s outflowing wind, which is incredibly hot and easily pushes a great deal of material away from the black hole itself, hence creating surrounding clouds. 

• MIRI was able to determine this by looking into several regions of the black hole and discovered circles of material at varying distances from the black hole. The final result of what made up these clouds of dust was very finely-grained silica dust, a relatively similar makeup to beach sand

This specific viewing of a core black hole was able to capture its contents in a precision never seen before, therefore being able to determine the composition of these surrounding gases, which was divided into two known spectrums

• The top spectrum contained various gases that had become ionized and very warm, such as iron, argon, oxygen, neon, and sulphur.

• On the other hand, the bottom spectrum contained much colder and very denser gases, which were mainly composed of molecular hydrogen and once again, silicate dust.

As we know, a black hole is not directly visible to the naked eye

In order to “see” them we must observe surrounding objects like stars or other planets orbiting it

In the case of calculating the mass of a black hole, we use the same observations except to a deeper lever

When the black hole and another star are in the same orbit around a mutual center of gravity, using accurate observations we are capable of measuring the speed and the distance of the stars orbit

Using these factors we are then able to excel determine the mass of the black hole using laws of gravity

For example, let's assume that there is a star like the sun orbiting a black hole and the star is traveling at 117 miles per second

then we detect that the orbit is very similar to the planet mercury, meaning that the sun orbits the black hole once every 12 days

The laws of gravity then tell us that the mass of the black hole must be 10 times larger than the star

Black holes are surrounded by a region called the accretion disc and it is composed of many different gas and dust particles, as well as any other matter that was pulled towards the black hole by gravity

When all these materials sin towards the black hole, it creates a hot and dense disc because of gravitational forces

Usually you will be able to find elements such as hydrogen, helium, and some other heavier elements

Sometimes when this disc becomes extremely hot, the elements become ionized, then forming plasma

In order to determine what material is found around the black hole, we can use x-rays

X-rays are produced in extremely hot and energetic environments, such as the accretion disc

On earth, we can use instruments such as x-ray telescopes, such as Chandra X observatory that are specifically created to capture and analyze x-rays from celestial objects

These x-ray signals in the accretion disc provide information of the composition of the element inside

Black holes are incredibly immense objects that due to their large gravity, have the power to distort and even twist the space-time of the universe around them. But it is a result of this power that we can observe them in a way, as due to these distortions of space-time, black holes go so far as to bend the very light around them. Using the bending of light, researchers are able to gain several insights about black holes, this including the rate at which black holes spin.

There are currently three known ways in which a black hole spins:

• Retrograde spin: where the accretion disk of the black hole (its circle of matter surrounding it) is found moving in the opposite direction of the black hole

• Prograde spin: where the accretion disk of the black hole is found moving in the same direction of the black hole

• Finally, no spin: where the black hole is not found to be spinning at all

As for the method in which one of these three spin methods is detected, scientists then begin to rely on the accretion disk, which is a phenomenon once again caused by the fact that a black hole has the ability to bend light. Scientists observe the accretion disk as the faster a black hole moves, the closer its accretion disk will be to its center.

• Scientists observe the accretion disk of the black hole as they have methods to extract the necessary information from it. They begin by assessing the X-ray light emanating from the accretion disk into an entire spectrum of different qualities, including mainly colours and energies. 

• One observation that can be easily made about the accretion disk is iron atoms scattered about in the accretion disk. If the accretion disk is found to be very close to the black hole, the colours found on the spectrum from the X-ray light will be largely spread out, as a result of the incredibly large gravitational pull closer to the black hole. 

• Therefore by using the degree to which the iron was found to be scattered around the accretion disk, scientists are then able to find how close the accretion disk will be positioned to the black hole. Then by using the aforementioned fact that the speed of a black hole is proportional to the closeness of its accretion disk, scientists can determine the rate at which a black hole spins