Mohammed's Annotated Bibliography

 

 

Source 1: University of Oregon

 

Citation of Source 1:

Mass Energy Equivalence. (n.d.). Retrieved October 22, 2015, from http://abyss.uoregon.edu/~js/ast123/lectures/lec09.html

 

Notes of Source 1:

As different objects move very close to the speed of light, relativistic effects begin to become apparent. There is no object that can move faster than the speed of light. The energy that is added no longer translates into a faster velocity, rather it gets converted into mass. This would mean that starships that are moving very close to the speed of light would experience an increase in mass. Physical concepts such as momentum become modified, since now it is dealing with relativistic mass. Below is a very famous equation discovered by Albert Einstein:

E = mc^2

This equation shows an equivalence between mass and energy. A small amount of mass is full of a large amount of energy. The increase in relativistic mass of an object is directly proportional to its energy. It is inversely proportional to the speed of light, squared. The idea of special relativity branched into the study of space, time, energy and matter. The famous equation, E=mc^2, was able to represent the link between energy-mass, whereas the special theory of relativity introduces the relation of space and time; spacetime. This expresses the fact that a fast-moving object (such as a starship) will observe time slower than a relatively a stationary observer. Studying relativity, and how space time is observed, led to the equivalence principle. This principle stated that there is no physical difference between a frame of reference that is accelerated and one that is in a gravitational field. If these frames are equivalent, then gravity can have special effects such as bending light. For instance, if a photon is shot to the right in a frame that is accelerating upwards, a bend in the pathway of the photon will be observed. According to the equivalence principle, the same will occur in a gravitational field. Therefore, gravity will have the ability to bend light. Now, if there is a massive body, it will have a gravitational field. This field will increase in strength as the mass of this body increases. When the mass is so high that the gravitational pull does not even allow light to escape, a black hole is created. The mass of this object represents the radius of the black hole (Schwarzschild radius), within which spacetime is infinitely curved. This radius indicates where the event horizon of this black hole is created. If anything surpasses this point in space, it will not be able to escape (not even light). A black hole’s mass is infinitely compressed to the center. This means that it is infinitely dense at a point known as the singularity.

 

Source 2: BBC (British Broadcasting Corporation)

 

Citation of Source 2:

Could we harness power from black holes? (n.d) Retrieved October 9, 2015, from http://www.bbc.com/future/story/20131203-could-black-holes-provide-energy

 

Notes of the Source 2:

Black holes are created when dying stars collapse under their own gravity to an infinitely small point in space known as the singularity. Black holes were once identified as a body in space where energy entering would be exhausted, and nothing else would occur. However, studies in the past few decades have shown that black holes are capable of emitting energy in the form of radiation. This radiation allows for the black hole to lose its mass, and get smaller. Slowly, but eventually, it will radiate all of its mass away and evaporate. Scientists have committed their time to understand if the energy sourced in black holes can be used in various practical applications. This brings upon the idea of energy extraction from black holes. One idea was developed by physicists George Unrah and Robert-Wald. This theory involved lowering a “box” attached to a rope-like mechanism near a black hole to capture energy. This process would be similar to the concept of lowering a bucket into a well. The bucket will collect water, than be raised and used for drinking and other purposes. For the means of energy extraction, the “water” in this case would be the hawking radiation that the black hole emits. This would be very difficult to execute because the force of gravity on Earth behaves a lot differently than that near black holes. Furthermore, since the box will be lowered into surroundings with high radiation levels, the box could collapse on itself and the string could melt. Due to the relativistic effects near the event horizon, the mass of the box could increase. This would require the string to be very light, but at the same time be very strong to be able to hold its own mass. Another method, proposed by Albion Lawrence and Emil Martinec in 1994, involves dipping a string into the black hole. The hawking radiation would climb up the string, much like current in a wire. This is a much slower process, and would require a series of strings to be placed around the black hole.

 

Source 3: Physics of the Universe

 

Citation of Source 3:

Mastin, L. (2009). Black Hole Theory and Hawking Radiation - Black Holes and Wormholes - The Physics of the Universe. Retrieved November 20, 2015, from http://www.physicsoftheuniverse.com/topics_blackholes_theory.html

 

Notes of the Source 3:

 

Black holes are a region in space time that splits spacetime into two regions; one where light rays can move, and the other where light and all other matter is trapped and cannot escape. In 1974, Stephen Hawking was able to come up with the theory that black holes are not completely black, nor are they immortal. He suggested that black holes emitted sub atomic particles in the form of what is called as Hawking radiation and exhausted energy. Hawking radiation is a thermal radiation that is emitted from black holes. This occurs through the conversion of quantum vacuum fluctuations into pairs of particles. These pairs are classified as virtual particles and split into the particle and anti-particle. The unique characteristic of these particles is that they would destroy each other very quickly, however this behaviour is different near a black hole. There is an immense force of gravity in this region. The negative particle escapes to infinity, emitting thermal radiation from a black hole. At the same time, the positive anti-particle, that has negative energy and negative mass falls into the event horizon of a black hole. As a result, the mass and energy of the black hole would decrease as it radiates it away. Hawking’s theory shows that smaller black holes emit more energy than they absorb, which results in a greater net loss of mass. This means that a smaller black hole would radiate away a lot faster than a larger black hole. Characteristics of a small, “primordial” black hole have been re-created on Earth, where CERN has developed a Large Hadron Collider that is able to accelerate two particles at very high speeds that they fuse together to create a black hole with a very tiny Schwarzschild radius.

 

 

Source 4: Kansas State University

 

Citation of Source 4:

Crane, Louis. "ARE BLACK HOLE STARSHIPS POSSIBLE?" (2009). Print.

 

Notes of the Source 4:

Hawking suggested that black holes are not black, but radiate a black body thermal spectrum. The energy increases as the size of these black holes decreases. Interstellar flights has become one of the more challenging projects in the human civilization. Deeper in space, there exist different conditions. A “shield” which a thickness of two feet of lead would be needed to sustain life for humans. Furthermore, the distance to even the closest stars is so great that it would require the speed of light to reach these destinations within a human lifetime. This is quite difficult as relativistic effects will come into play. In 1955, John Wheeler suggested that if enough energy could be focused into a region of space, a microscopic black holes would be formed. This microscopic black hole would theoretically feed in its radiation for the purposes of propelling interstellar spacecraft. This black hole needs to exhibit the following properties to be able to do this. Firstly, it needs to have a long enough lifespan so that it can supply the energy to the starship. It also needs to be powerful enough to accelerate itself very close to the speed of light. In terms of size, it must be small enough so that its energy is accessible. However, it should be large enough to provide enough energy over the required period of time. Lastly, the mass of this microscopic black hole should be comparable to that of the starship. Through many calculations, it is observed that a black hole with a radius of a few attometers (1x10^-18m) would exhibit these properties. For this black holes, solar panels would be needed to be placed to capture the Hawking radiation that is emitted. They would be ideally be placed close to a 1,000,000 km away from the event horizon. This black hole would have a mass of a million tonnes and its lifetime would vary from a few decades to centuries. Along with black holes, there are also other methods that can be used for the propelling of these interstellar flights. One alternative to the source of energy is the use of antimatter. However, antimatter is very expensive to use. Furthermore, it is very difficult to contain large amounts of it on Earth. Another alternative would be powering it through nuclear fusion or fission. However, this process is very inefficient, because only a small amount of energy is yielded from this reaction. Therefore, an interstellar vehicle would have to carry nearly a thousand times its mass of such reactants to produce the reactions needed to fuel it. This process is therefore way out of reach.

Source 5: National Aeronautics and Space Administration (NASA)

 

Citation of Source 5:

Missions - NuSTAR - NASA Science. (2012, June 13). Retrieved December 4, 2015, from http://science.nasa.gov/missions/nustar/

 

Notes of the Source 5:

It is important to understand the past, present and future of these fascinating regions of space. Spacetime is a physical concept that combines space and time into a single interwoven continuum. Up to the 20th century, it was believed that time was something that ran the same for everybody, wherever they are in space. There was great amounts of research into the spacetime, and energy-matter relations, after which the theory of general relativity was established. This theory led to the prediction of black holes. In the 21st century, the need for understanding black holes is becoming more apparent. In 2012, NASA launched a telescope called NuSTAR as an explorer mission which studies the universe at high energy x-rays. These regions in space are where black holes hypothetically reside, as they emit energy in the form of radiation. This device would answer many questions that are posed about this phenomenon. One of the ideas that this telescope will explore is how these black holes are distributed in different regions of space. In the past couple years, there have been a few accomplishments. This mission was able to capture the rare blurring of black hole light. The source of x-rays (known as the corona) that resides near a certain black hole, collapsed into it. The strong gravitational pull stirred the corona into the black hole, resulting in a stretching of x-ray light which was observed by the NuSTAR. It was also able to measure the spin rate of a black hole whose mass is 2 million times that of the Sun. It also suggested that a black hole may potentially be a neutrino factory. This means it consists of neutrinos, a fundamental particle and one of the building blocks of the universe.

Source 6: TestTube Plus

 

Citation of Source 6:

Plus, TestTube. [testtubeplus]. (2015, August 29). What can Black Holes Be Used For?[Video file]. Retrieved from

     https://www.youtube.com/watch?v=QusNHDjDBFs

 

Notes of the Source 6:

It is important to understand how black holes are detected. They are massive spaces which are undetectable by a human eye. One method that can be used for the identification or location of a possible black hole is through the observation of stars. There are many stars in our galaxy and they are moving. It may be observed that the stars are orbiting around an invisible space that is difficult, more so impossible to detect with a human eye. This may indicate a possible presence of a black hole, since the stars are pivoting around something massive that is invisible. Another method in detecting the presence of a black holes is by studying the radiation that it emits. If there are bright, x-ray emissions observed in space, there is a possibility that they are coming from a black hole. This radiation is Hawking radiation. Hawking proposed that smaller black holes emit more of this radiation than larger ones. Some black holes that lose more mass than they gain it, are known as micro black holes. Eventually, these black holes become so small that they vanish. This is known as black hole evaporation. What can these black holes be used for? The large amounts of radiation that is emitted by these black holes can be used as an energy source for an engine to power a starship. Although this is a field of research on Earth and in our civilization, there is a possibility of extraterrestrial life already using and applying this concept. Hypothetically, if extraterrestrials are travelling across space time in a starship, they can use the radiation as an energy source. This radiation that will be exhausted, meaning that it will leave the starship once it has been used for power. This can cause a radiation spike in the atmosphere, which can be detected by humans.

 

Interesting Facts!

1. Black holes cannot be seen. This is because light is unable to escape from it. Even instruments are incapable of finding the location of black holes. Black holes are identified based on the characteristics of a certain environment. For instance, one way to tell is when a star stars to bleed towards the black hole. Its movement gets faster, it gets hotter and emits bright X-rays that can be measured.

2. It is very like that a black hole(s) in the Milky Way Galaxy. However, Earth is in no danger of getting sucked in by this location of high gravitational field because of our proximity to it. We are therefore able to observe its properties and behaviour from afar.

3. Information Loss (aka black hole information paradox) remains to be an unsolved concept. This concept questions whether the hawking radiation emitted by black holes is purely thermal. If the black holes is purely of a black body, it will have no information associated with it. All of the information regarding the formation of the black hole will be gone forever once it evaporates. This leads to two possibilities

4. 1. Possibility # 1: The information of black hole is completely lost, the radiation is purely thermal

   2. Possibility # 2: Some of the radiation that is emitted from the black hole is modified so that it is not purely thermal.

Two physicists, Hawking and John Preskill and Stephen Hawking support different theories. Hawking believes in the first possibility, whereas Preskill agrees with the second one.