The Unknow Universe - Dr Richard Hammond

The Unknown Universe describes how physicists interpret the creation of the universe and the components that connect it. From dark matter to the string theory this book covers vast amounts of information pertaining to modern physics theories and developments. It relates the old to the new and points out unique, well thought ideas of Hammond into an interesting, clear perspective for the reader.

Chapter 10: Mysterinos

Aside from the title being a made up word, Hammond makes some interesting points in his final chapter. This entire chapter entails all the ‘particles’ that were or are thought to exist based on theories. However, Hammond discounts many of them and explains why they can’t or most likely don’t exist. He begins by introducing a type of particle called tachyons. These particles are simply anything that can travel at astronomical speeds. There are many skeptics for these types of particles because we can’t see them and it is believed that nothing can travel faster than the speed of light. Hammond continues by defining them as more of a ‘mathematical curiosity’ as oppose to an actual physics related particle. Next Hammond defines negative mass. To put it simply, it’s just the negative value of a mass. Following his example, its best represented in the equation F=ma where force and acceleration have directions and mass is scalar. If this were a normal case where the mass is positive, if you push on a ball with a northerly force, it will go north. If it were to hit a wall the wall would exert a southerly force and it would bounce back going south. If we take this same situation and apply a negative mass, the ball would hit the wall but the negative value of the mass causes it not to bounce back in a southerly direction, but continue toward the wall. This results in an increasing acceleration at the wall as the wall continues to push back until eventually the ball goes thorough the wall. This is a very neat thought because if you apply the logic and the process of aligning the arrows as we set up in our diagrams, this is what would happen. It is a simple yet intriguing thought. These were the two main ideas within the chapter that captivated me the most and the fact that it was dealing with equations that I’ve used and understand makes it that much more interesting because I can correctly interpret what Hammond was describing. This was an ideal chapter to conclude the book with as it answered, or at least attempted to answer some of the unknowns that Hammond left the reader through out the course of the book.

Chapter 8: String Theory

The string theory is essentially the image of “ a one-dimensional object that revolutionizes our world more than Starbucks”. Hammond looks at the string theory as a one-dimensional object that can come in various different forms that correspond to a different component of the universe. For instance, one shape of that same entity can be a proton while another can be a neutrino. This theory essentially simplifies things into a simple format so that further things can be explained and understood. If these different shaped, yet similar particles were depicted as one-dimensional lines, they could be plucked to emit different sounds/ frequencies. This is simply for visual aid so that it is easier to understand how a particle can change. Next if this string were an electron, and it was struck with something that provided enough energy that it made a second wave on the string, this electron would be changed or manipulated into another particle. Similarly, if the string were to break, it would be bale to decay or form other new particles. This theory essentially stems from the visual aid of a string and how it can be manipulated to show that everything can be derived from a single entity with varying shapes and sizes. The string theory also shows a representation of an electron having wave like properties, which is important in the understanding of how it can interact with other particles. The next step, the String Theory Revolution introduced a new aspect to this theory in 1984. This became quite complicated but I interpreted it as the string theory has two types of particles, fermions and bosons. Fermions are particles that are more associated with matter and can only occupy a space in time. They are often usually elementary particles like and electron. Bosons, however, are other types of particles that can occupy more than one space at a point in time if they have the same energy. They are often also referred to as force carriers because of this multi placed characteristic. Another difference between the two, which I don’t fully understand, is the rotation type that the particles have. Fermions have half integer spins while bosons have full integer spins. These are the ideas being the string theory and how Hammond portrays them through conversations, explanations and examples.

Chapter 7: Ashes to Ashes - Things we Know

The things we know about the universe and the laws of physics are quit interesting and happen all around us at all times yet we often fail to see them in action. Friction for instance is a force that causes a resistance in the direction of motion of an object (kinetic), or keeps things from moving in the first place (static). Friction is one of the understood aspects of physics that we can apply laws to such as the law of conservation of energy. When there is friction in a system, some kinetic energy is converted into heat through the contact of the two surfaces. Other physics related things that we know exist are the inverse square law that describes how many things in physics including sound intensity work. In this case, the inverse square law states that the sound intensity is inversely proportional to the radius or distance from the sound source. Other things that have been proven include the Doppler effect, as discussed in chapter 1, and Sir Isaac Newton’s 3 laws of motion. The first being, all objects at rest remain at rest and all objects in motion continue in motion unless and external force is acting upon it; the second is the acceleration of an object is inversely proportional to its mass and the third is every action has an equal and opposite reaction. Essentially this chapter is nice simple review of what we have learned up to this point in physics with the exception of a few ideas that were a bit over my head and not formally introduced.

Chapter 6: Quantum Gravity

This chapter is the largest chapter in the book so identifying and describing my favorite idea from this chapter was quite difficult. I chose to focus solely on the properties of gravity and how it applies in various different situations like when the fourth dimension, time, is introduced. But first I found it quite interesting that Hammond went against what most theorized when looking at gravity. As he described it, many physicists consider gravity to be the weakest of all the forces but he thinks it is one, of if not the strongest of them all. For instance Hammond describes how the nuclear force of electro repletion between particles can be overpowered by gravity if an object has enough mass. More specifically, if I were to sit in a chair, the gravitational force would equal that of the electro repulsion forces between the chair and my body. If a gorilla were to sit on the same chair however, the chair may break, meaning the increased gravitational force (resulting from the increased weight) was able to overcome that of the electro repulsion forces. I can understand what Hammond is saying in this case but there are still some minor details that need to be clarified to fully know what is actually happening. Personally, the way I interpret it is the electro repulsion forces pushing up should essentially be the same force that we talk about in class, the normal force. Because Hammond does not outline this, I am not sure if my interpretation is correct, but if so then it is a very interesting way to use such a simple example to over rule many great theories relating to the strengths of various forces.

Like I said before, the forth dimension of time can be introduced when referring to relativity. This is where things become very interesting and a lot more abstract in terms of thinking. The example that Hammond uses to explain it best is that time slows down in a gravitational field. Hammond explains it by saying “atoms near the surface of the sun, being in a stronger gravitational field than those of the same atoms here on Earth will emit longer wavelengths of light”. This essentially means that relative to a specific point, the more gravitational force an object is exposed to, the slower time will travel for that object. It is a difficult concept to understand and I was not able to visualize much more than those simple examples. However, I can take this theory and understand why astronauts are seconds younger when they come back from long space missions than if they were to stay on earth. This is because they were exposed to less of Earth’s gravity and thus time passed slower for them while in space. Next time I need more time to do a lab I know where to go.

Chapter 5: The Higgs Particle

This chapter outlines the ideas behind other possible particles that account for various unexplained occurrences through out the universe. It continues to outline ideas from the fundamentals of protons and neutrons to more complex photons and neutrinos. One of the most interesting ideas in this chapter is the breaking down of particles into their possible components that scientists have found. Some examples of these smaller particles include quarks. Quarks in general are quite fascinating because “they interact the way other particles do, by exchanging virtual particles such as gluons”. Quarks are also massless, like photons, and have a spinning motion at all times. However, quarks are unique because essentially every other known force in the universe has an inverse relationship with distance (as the distance increases the force decreases) but with quarks this is not the case. To explain how quarks work in this situation, we must first understand the equation E = mc^2 as it describes that matter can’t be created nor destroyed but it can be converted into energy. The unique thing about quarks is that the distance between two quarks does not influence the force between them. In fact, if you were to separate two quarks 10^-15 meters apart, you would produce enough energy to make two new quarks. This is where that famous equation comes in handy; in this case energy is converted into matter. As a result of this law, one cannot ever have a single isolated quark because the energy required to do so would simply produce more.

Another interesting aspect of this chapter was the brief understanding I got of the Higgs particle. Much of the descriptions and understanding was a bit over my head but I was able to understand that scientists are having a hard time observing and understanding it because of its unique properties. This is partially due to its unique properties and its massive weight, in relation to other particles. It is believed that it weighs about 120 times that of a proton and as a result, it is difficult for scientists to gain an understanding of its standard model. There was not much else I was able to draw from this chapter due to its complexity but the information that I was able to understand was very intriguing to say the least.

Chapter 4: Renormalization

This complicated development in the history of physics was started by the classic gold foil experiment that we are all aware of. It was carried out by Rutherford and he was able to determine that the model of the nucleus was incorrect. This baffled scientists at the time because it negated many of their carefully deliberated theories on how things, like atoms, were connected through out the universe. A theory was proposed that the electrons, a negatively charged particle orbited around the nucleus but that was disproved after it was noted that the electrons gave off energy and thus would spiral into the center of the atom almost instantly. The solution to this was not found until later but for the time being it caused much disruption among physicists. The next large alteration of physics theories during this time was the ultraviolet catastrophe. This involved an experiment where theoreticians took an object, such as a lump of coal, that radiates heat and put in an enclosed box with a small hole in the top. The heat would radiate from this hole and they would measure it, breaking it into a rainbow like spectrum with a diffraction grating. The measurements were all consistent and seemed to make sense based on their predictions on how much energy was radiated. Unfortunately, when finding an exact value using equations, there results showed an infinite amount of energy being emitted. This was essentially a break down of some of the previously thought, strong theories of thermodynamics. With these new developments in testing, theories were rapidly being disproved. The book uses the analogy, “It is similar to a staircase vs. a ramp, and to get the total energy you must count all of the steps; break the continuous spectrum, the ramp, into small the but discrete steps-the photons. When you count the steps you get 12 or 14 (proving it works on a larger wavelengths), but the ramp has indefinitely many tiny stairs, and when you count them you get infinity.” These realizations caused much confusion in the minds of physicists during this time. Its too bad they didn't have the grade-9 science textbook, that would have helped a bit.

Chapter 3: The Cosmic Ray Paradox

Cosmic rays aren’t fully understood and in 1912, it was a wildly-debated topic. From Hess doing experiments in hot air balloons hundreds of meters off the ground, to Aden and Marjorie Meinel's (two retired astronomers) attempted connections to climate, cosmic rays have baffled many of the most brilliant scientist through out history. Today we have a reasonable understanding of how they work and where they come from. For instance, most of these particles, or cosmic rays, are results of a supernova explosion. Supernovas occur after a start is depleted of its reactive elements such as neon and selenium until it turns into iron. Next, Hammond explains, “ For nuclei lighter than iron, the attractive nuclear force greatly overpowers the repulsion of protons, which is why fusion gives off energy.” It is at this point where fusion ceases and it begins absorbing energy. At this point fission occurs. This was the first part of Hammond’s description of a supernova but it lacks detain in his explanation. However it is a very interesting process in which I understand the basics and the main reactions that case step one in the process. Next a neutron star is created when the gravitational forces become so strong that the electrons and protons of these larger iron and other elemental atoms become incredibly close together. These neutron stars emit neutrinos into the universe. Finally, when the mass becomes too large, it collapses on itself in the most violent explosions in the universe. These explosions send elements and cosmic rays in all directions scattering them across the universe. Although not as detailed as it could have been I still feel that Hammond did a sufficient job in identifying the process of how a supernova explodes and sends out cosmic rays.

Chapter 2: Dark Matter

Dark matter, its something we’ve probably all heard of but never understood…that’s all right, no one does. It was discovered when astronomers were looking into the various types of energies that galaxies, as a whole, possessed. When observed, galaxies had kinetic, spring and potential energy in one form or another. These energies can be measured but after many trials and results that simply didn’t make sense, scientists concluded that the total amount of mass in the galaxy could not be accounted for visually, therefore there was matter that we could not see. However, this unseen matter was not because of the fact that we are too far away to see it, it was because it is invisible. This leads into the most interesting point within the chapter that explains how dark matter influences the speed at which objects, like stars, move around the center of galaxies.This movement, alters the energy within a galaxy. Hammond explains how the farther away a star is in relation to the center of the galaxy, the slower it travels. Upon reading this I made the connection to our centripetal force lab, as the radius became smaller, the velocity increased; the same outcome applies in this case. For instance, in relation to our solar system, if you were to speed up the rotation of the planets around the sun by 7603200 times, it would take Mercury 1 second to orbit around the sun while it would take Pluto 20 minutes. To connect this to dark matter, you must fist understand some of it other characteristics. Scientists have concluded that the density of dark matter decreases inversely as it gets farther away from the center of the galaxy. The reason is unknown but again because it is just a theory, these characteristics must be given for the system to work and be somewhat understood. Another characteristic associated with dark matter is that it has gravity just like any other type of matter. Scientists have come to the conclusion that there are possibly two types of dark matter, hot and cold. They were given this name because hot is associated with more energy, and cold less. An example of a hot type of dark matter would be a black hole and an example of cold dark matter would be a neutrino (a very small, neutral particle that doesn’t react very much with mass). Its an interesting idea but NASA has found more proof, based on previous understandings, that dark matter can exist. They concluded that light bends around large objects, like galaxies. The amount of bend, however, is directly related to the mass of the object, or gravitational force. A galaxy, though big, wouldn’t have enough gravitational force or energy from the planets to do this to the extent that we observe. This means that there has to be some sort of unseen matter that influences this phenomenon and dark matter provides that solution. Its an interesting thought that some sort of dark matter, in this case cold, can be passing through us at this very second and that it can bend light. Dark matter is everywhere in the universe and, according to the idea, it is the most plentiful type of matter in the universe.

Chapter 1: Cosmic Acceleration/Chapter 9: Origin and Expansion of the Universe

Its interesting to see, looking up at the stars and wondering about how the universe started. I know I’ve asked myself that question once or twice. As we all know, there are many theories that show how the universe began, some more believable than others, but they all have their valid points. This chapter outlines how the scientific community has been able to prove the rapid expansion of the universe and use light to try to understand it.

Light is one of the main focuses within this chapter and as we have learned in physics classes, elements emit their own unique wavelengths of light that translate into different colors on the light spectrum. Scientists have used this understanding, along with advancements in technology, to locate specific elements through out the galaxy and beyond. It is interesting to know that one can look into a telescope and see something millions of kilometers away that isn’t visible to the human eye if it were on the tip of your nose. This Understanding of light along with another previously learned phenomenon, the Doppler effect, not only shows us what is millions of kilometers away, but what its doing. Take the distant galaxy NGC 4860 for example; because the Doppler effect is the result of the difference in wavelengths as something is moving, we can interpret the change in wavelengths (gradually increasing from 656nm) to show us that the galaxy is moving away from us. In relation to this, Edwin Hubble, a renowned scientist, was able to create the equation v = H x d which essentially states that velocity of a galaxy is equal to a constant, H times distance, d. The H constant in this case refers to, you guessed it, another fudged number that represents a key component in determining the velocity at which the galaxy is moving away from the earth. It was given the letter H in honor of Hubble. The d is the distance away from the earth, therefore, according to this equation and Hubble’s work, the farther away a galaxy is from the earth, the faster it is moving. With this we can finally make reference back to what the chapter is about, the expansion of the universe. Because we know that these galaxies are moving away from us we can say, with great certainty, that the universe is expanding at the speed of light. It is an interesting thought and as you look up to the stars you now know that there is an ever lasting and increasing space that will never end. It is also interesting to know that in the time it took you to read this chapter, millions of kilometers have been added the universe. Although a strong theory now, we are not certain that this is the case. Despite this, it is very fascinating to view the universe in such a manor.