Why do we understand the universeWhy do we understand the universe**
Recommendation : 【Philosophy】 Chapter 1. What is knowledge
References
The Comprehensible Universe - Stenger, Victor J
Why is the Physical World So Comprehensible - P.C.W. Davies
The world we can see
If you look at the sky at night, you can see thousands of stars that are no different from our sun. If you look at them through a telescope, you can observe more stars and galaxies. Using data collected through telescopes, astronomers have discovered that our sun is roughly one of the 100 billion stars in our Milky Way. Outside our galaxy, there are about 100 billion other galaxies with 100 billion stars, at least 10 billion light years away. And this is just the information we’ve got up to the event horizon. Modern astronomical models show a much larger universe beyond the horizon, and this model may even explain other universes.
Let’s move our eyes to Earth, the ocean, clouds, mountains, deserts, and plants and animals. And, once again, our scientific instruments reveal the world of microscopes and, at best, the world of atoms that show a superficial appearance.
The enormous size and complexity of the universe and the strangeness of the microscopic world have led many laymen and scientists to speculate that the universe will forever be surrounded by mystery. Of course, it has already been suggested that humans with limited intelligence will never be able to contain more information than data that comes to our senses and instruments.
In this book, I have challenged the assumption. The universe is understandable. Away from the mysterious mysteries, existing physics and astronomy are within the scope of our understanding. Here’s a brief summary of our efforts to learn and draw some general conclusions.
Luminous objects
The great success of physics strongly suggests that physics is not just a tool. These models have surprising predictability for areas that have not yet been observed to simply view the world as operating at random. Surely physics is talking about the ultimate reality. However, as I emphasized, the models we use to describe what we observe do not need to mimic the real world. It still makes sense if the models don’t imitate the world. If a model presents an appropriate prediction, it could be used to predict the future.
In the next chapter I will contemplate the reality of nature, but I may be somewhat disappointed that we have found only at least two metaphysical models that rely entirely on observations. Because it is the simplest, my preferred model is the hypothesis, atomism, that the world consists of underlying particles and they move into other empty spaces. I’ll call this “atomic theory and vacuum.” To me, this is an understandable universe.
But I have to admit that there is another metaphysical model favored by mathematicians and some theoretical physicists. This is called the Platonic model, which is the idea that the world is not composed of materials such as electrons and quarks, but rather of an abstract space, quantum field, described in mathematics, regardless of time-space. For most people, including myself, this is an incomprehensible universe.
However, before explaining those perspectives more specifically, let’s look at what we can understand with confidence. Above all, in science, we gain knowledge through the method of observation. Observation can be seen as a process of kicking something and finding out what the object is to be dumped. As a process of recognizing these cold-dashed objects, I explain more accurately the process of energy and momentum transfer found in all observations. At this time, matter is defined as an object that transmits energy and momentum to the observer. This material can be recognized as a distinguishable object by being named with data obtained from a specific motion. This model makes more hypotheses about such characteristics, and they are all tested through experiments and observations.
Now, this model does not seem to include non-material things in reality by definition. In fact, someone thinks that science has limitations in interpreting a field materially. However, both ideas are wrong. If a purely matter-dependent theory provides sufficient description for all observations, no additional components are and need not be part of the model. On the other hand, if purely material-dependent theories are insufficient, there is a reasonable reason that additional elements are needed in our model. In this case, nature contains some non-material element. So far, no non-material element has been proven necessary.
As described in the space-time model, the most representative form of observation is the way light emitted from a light source bounces off an object and reaches our eyes. Or maybe the object we’re looking at is that light source. Even if we don’t “kick” them ourselves, they “praise” us. Our other senses (sensory, auditory, and tactile) include similar processes.
In careful experiments, we quantify our observations by shooting detection particles that can measure momentum or energy changes, such as photons, at objects in the laboratory. Therefore, the basic measurement process can be seen as the momentum and energy exchange between the observer and the observation object. Along with scientific tools, we can extend the range of observations by using photons outside of visible light or other particles such as Nutrino. Scientific observations are more accurate and more quantified than all other human observations, but human observations are also quite quantified. For example, in our lives, we often remember an event as a specific time and place.
In science, an atomic clock provides a standard of time, and other clocks are synchronized with that atomic clock. According to recent tradition, the distance between two points is defined as the time it takes for light to travel between them. In Chapter 2, we discussed the use of atomic clocks after shooting light to unobserved points. By timing the returned signal (assuming it exists) The position, speed, acceleration, and other physical variables of the object can be measured. Note that the aforementioned spatial-time model is a model designed to describe these observation methods. We have no other way of looking at objects in so much detail, no way to prove that nature is really made up of such objects, and that terms such as distance, speed, and acceleration are the real elements of nature. We can only discuss that this model is simple and consistent. As long as we show consistent results for all data, we can safely draw reasonable conclusions.
The space-time model is not our only option for describing data. In the 1960s, physicists tried to remove space and time from their theoretical models and developed a model represented only by momentum and energy (especially four momentum), S-matrix theory or bootstrap theory. This approach stems from the fact that the fundamental process in physics is inter-particle interaction. However, the model was less predictable, and was abolished by the discovery of quarks that strongly suggested that the vacancy-time model was valid. Nevertheless, in S-matrix theory, the Venezuelan model provided a cornerstone to develop into a superstring theory. The superstring theory states that it can explain the world if not just a four-dimensional variable, but more dimensions are woven on the Planck scale.
In our four-dimensional space-time model, particles are defined as objects such as points that are too small to be measured. Observations have led us to hypothesize that all measurable objects are a set of underlying point materials. Standard models such as quarks, leptons, and gauge conservation correspond to all data. If the underlying object is a string or m-brane (a dot is 0-brane, a string is 1-brane, a face is 2-brane, etc.), they are so small that in some future they will be seen as particles such as dots.
Objectivity secured
Given our material model of reality, and with space-time, we can combine what humans have observed in history with that model. As we can see one object from different perspectives, physicists have realized that data should not be interpreted from a particular person’s point of view. Of course, it would not be wrong in that such a model relies entirely on observation. However, such an interpretation is subjective and unlikely to represent the truth about this world. Perhaps more precisely, these subjective models may be meaningless when viewed in different frames. Science has always sought objectivity, because history has shown that these methods will yield better results. In order to secure an appropriate opportunity to create models representing objective reality, physicists have attempted to formulate such models that other observers can see the same way. As they formulated the model, they felt the need to postulate something (find more basic rules) to get what might be called the rules of physics. Indeed, we needed to describe this nature by constructing the simplest mathematical rules possible.
This is similar to the way our brains process information through our eyes. Each eye measures a two-dimensional image and energy (color), and combines the two pieces of information to produce a three-dimensional image similar to that of all observers.
Usually, we regard the rules of physics as conditions that constrain the behavior of matter. Surely conservation laws are traditionally so. For example, a thrown ball can only go as high as its energy allows. But a century ago, Emma Noether proved that the law of conservation of energy, the law of conservation of linear momentum, and the law of conservation of angular momentum are deeply related to the symmetry of space-time. In that sense, energy is a mathematical element over time. But as we have already seen, energy is a measurable target. Our eyes are measuring energy in the process of recording colors. But we’re only going to deal with the general device for measuring energy, the calorimeter.
A simple but highly inaccurate calorimeter can be made with a thermometer that measures the temperature of water and an isolated meter with water. Moving objects go into the water and slow down. The initial kinetic energy of the object is measured by the change in the amount of heat of water that can be measured by the increase in the temperature of water. Here, there is a hidden assumption that the lost kinetic energy has been converted into thermal energy. The rest of the energy can also be converted into heat when a chemical reaction or nuclear reaction occurs. If the experimenter wants to analyze more accurately, other energy-reducing factors such as sound generation should be identified.
Let’s say we don’t have any tools to interfere with the motion of an object, not just a calorimeter. Then we can assume that the object will continue to move with constant energy. What would happen if energy was not conserved here? If so, objects can slow down or stop as they move into certain empty spaces. It could be similarly faster. Because nothing can stop an object from speeding up. In general, the measured mass will change or such a combined effect will appear.
In classical physics, mass is the invariant static amount of an object. Momentum is literally the amount of moving objects and is an invariant dynamic amount. Energy is the ability of an object to work, and work is a useful application of force. These physical quantities are defined in basic physics textbooks.
Suppose simply that the mass of an object is a constant, so that any change in energy can be measured through a change in velocity. Then, let’s make a video of an object moving in an empty space. If the energy is constant, we cannot know what time a particular frame means. That is, we cannot divide each frame with a clear criterion. On the other hand, if the energy is not a constant (if the law of conservation of energy changes due to the behavior of observation), each frame of the video can be differentiated over time. And you can find the invariant between energy conservation and time.
What happened in this phenomenon? The special rules that make up the universe, called energy conservation laws, keep isolated objects moving with constant energy.
I provide an alternative perspective. Energy is a concept invented by our physicists and is defined to be measurable with a calorimeter. From any point of view, the amount must be time-independent, so that consistent results are produced (i.e., in this case, regardless of when the clock is started).
Let’s be more precise about this. If we want to create a space-time model that does not depend on the perspective of a particular observer, the model needs to include the concept of energy that is somewhat abstracted in meaning, although it implies figures read from a calorimeter. Similarly, the model should also include the concepts of linear momentum and angular momentum.
Now, such discussions were possible when Helmholtz discovered the law of conservation of energy in 1847, before Nutter discovered her theory. However, in retrospect, although energy was not a clear element of Newtonian mechanics, Newton’s law could induce an invariant amount in time, indicating that it implied energy conservation inherently. In fact, the law of conservation of energy is a law that a freshman in college can derive from Newton’s law.
Possibility of refutation
A similar argument applies to other conservation laws. As a measurement method, functionally defined linear momentum and angular momentum, charges, nucleons, and several other quantities should be able to be conserved in other spatial-time models. This conservation law then becomes a general principle, not a law. In fact, they are “non-law,” or “lawless law,” which is my preferred title. Pointing to a particular position and direction in a spatial-time model requires some motion that we can interpret as a law. But what we want to see instead is not to think of such a movement. Nevertheless, we hope that it does not rely on a particular point of view to express an objective reality.
If it depends on the perspective, we will give a serious example of abandoning the principle of perspective independence. In the late 1920s, the energy spectrum of beta rays from various atoms was measured. The underlying principle was due to beta decay in which one neutron in the nucleus turns into an electron and a proton, and beta rays were measurable through electrons. Because the initial momentum of the neutron was zero, the protons and electrons had to have the same magnitude of momentum in opposite directions. (The kinetic energy is derived from the neutron’s mass defect.) Since the electron’s linear momentum was fixed, the kinetic energy of the electron had to be fixed. However, this was different from the observations. Rather, the energy of the electron drew a continuous spectrum.
This experiment implied that energy had changed into other forms or that invisible particles had been created. The latter possibility was the law of conservation of angular momentum. This is because all three particles had a spin of 1/2 and there was no way to match the angular momentum in the three-particle reaction.
In 1930, Wolfgang Pauli suggested that the invisible particle would be a Nutrino with a spin of 1/2 and a very small mass, as Enrico Fermi had speculated. Twenty-five years later Nutrino was first identified in the laboratory.
Now, suppose that no Nutrino is found and the reaction always forms only two particles. This violates the law of conservation of energy, conservation of linear momentum, and conservation of angular momentum. This implication implies that the rules introduced to describe our observations are well related to explaining the observations. Until now, the rules have never been found to be wrong.
It also shows why the things we introduced do not conflict with postmodernism. In postmodernism, anything works. But this is not true in physics.
In summary, the perspective independence principle used to provide the basis for our model is remarkably testable and disposable. And it has never been disproved.
Concept of Power
Now let’s recall our concept of power. In classical physics, conservation laws involve equations of motion and the concept of force that describe the motion of an object. In quantum physics, such equations describe the average motion of an object. In general terms, force is a factor that causes an event, such as a change in motion of an object. However, we know that all fundamental forces are physical quantities designed by physicists so that equations of motion do not contradict each other even between different perspectives.
Centrifugal force and coriolichim were proposed in classical physics, allowing Newtonian law to still be applied in rotating systems. Note that these forces do not exist in all frames. If you’re floating on the earth and you’re watching the earth spin, you don’t have to use centrifugal force and coriolis to describe the motion of an object. However, if you want to use Newton’s law in a fixed place on Earth, you need to introduce these forces to preserve perspective independence (the Newtonian mechanics here).
Einstein realized that gravity is the same as the result from other perspectives. An observer falling under a uniform gravitational field does not experience any gravity. The observer’s situation is no different from that of the observer in the capsule far away from the celestial body. On the other hand, an observer watching an elevator fall down with acceleration above the Earth will feel that the acceleration is working on the elevator. And it would be the same situation as the observer in the elevator accelerating at the same inertial acceleration. However, such inertial forces are fictional forces like centrifugal forces and coriolichim.
So what accelerates an object to the surface? We call this gravity, as our classical description states. Or if someone wants a general theory of relativity that is independent of perspective, we will explain that an object is moving along the shortest path on a curved surface called geodesic.
It depends on the model. In this case, the general theory of relativity is a superior model. In many cases, however, different models describe phenomena that are sufficient but contradictory to each other for the same phenomenon. At that time, it is difficult to see one theory as a real reality compared to another theory.
Indeed, the exercise itself is something we have created. Recall that when we define space and time, we came up with measurements using clocks and objects moving in space. The rule of force guarantees a consistent configuration for this model. In other words, the process (composition?) is not arbitrary. Exercise and power, despite being our inventions, have done what no old model has done. This model will accurately describe the observations.
The proposed space-time harmonization in our model involves Galileo relativity that objects running at constant speed have the same perspective. However, the area where the Galileo transformation is applied is limited to objects moving at a speed much less than the speed of light. A more general perspective due to Lorentz transformation can cover all speeds. Once we have obtained the Lorentz transformation and have a suitable form of momentum and energy to remain consistent, we have obtained results such as time expansion, Fitzgerald-Lorentz contraction, and E=mc2. In other words, it can be seen that special relativity was influenced by our desire to describe objective reality.
As we have seen, along with the Lorentz transformation, Mach’s principles, which I called the Leibniz-Mach principle, led to the development of general relativity. It can also be seen that this principle is the influence of efforts to objectively describe nature. Objects in space cannot accelerate by themselves. There is no object that can accelerate itself. A second object is needed.
Einstein realized that the energy-motive force tensor at a given particle’s position affects other nearby objects, that is, all other objects in the universe. Tensor is an extension of the Lorentz variable to the concept of mass or energy density. Density depends on the perspective; the energy-momentum tensor used for a single object is not. Tensors are generalizations of vectors. A vector is a set of things on a coordinate system that are constant with respect to an arrow and the angle and magnitude of rotation. Tensors are also a set of variables whose components may vary but whose rotation and size are constant. When moving from one point of view to another, the transform equation is required.
In the Einstein model, another tensor called the Einstein tensor contains Newton’s gravitational constant G and is equated with a linearly increasing energy-motive force tensor. This tensor is considered a gravitational field in general relativity. In Einstein’s model, a particular mathematical technique can explain the geometry of a given space in a space-time system, although it is not the only way to describe nature, and is simple enough to allow for various explanations with metric sensors. Without further assumptions, Einstein’s general relativity is inducible.
Constants
So what about the constant G? Where does this constant come from? Like the speed of light c and the Planck constant h, G is also considered a questionable object by some physicists. However, as we have confirmed that c and h are arbitrary conversion coefficients, G will be applied equally. The magnitude of the force of gravity is not an adjustable measure! The specific value of G is that it is a unit that you must have in order to describe the system. You can also fit all physical calculations to h=c=G=1.
Now, this is not to say that nature’s other forces are arbitrary compared to gravity. The advantage is that it can be expressed on a dimensionless scale. That is, it can be set to an integer multiple of the proton mass. In principle, any mass may be selected as a unit mass. However, in all cases, the relative force of gravity depends on the mass parameter, which also relates to electromagnetic force or other basic force. The relationship between mass and gravity is the same as that between charge and electromagnetic force. Numbers without dimensions that measure the relative forces of forces will one day be calculated by fundamental theory, but at present we must determine their value in experiments. So far, we still have to allow the possibility that their value-giving may in fact be our mistake.
Lawless Laws of Vacuum
Experimental data do not always represent a set of rules that matter must obey. Our observable universe also seems virtually devoid of any element. The laws of physics are either “ruleless rules” or “lawless laws” from a very poor plan. They are the rules of the vacuum.
Let’s think of radioactive decay. Hundreds of examples have been studied fairly accurately since the early 20th century and all these data have indicated that the events are random and impersonal.
As discussed in Chapter 6, the exponential curve of radioactive nuclear decay showed that the probability of decay would be constant at every hour interval, and would be time-independent. In radioactive decay, more exponential distributions are observed than flat because the number of atoms decreases as they collapse. According to the language we have developed in this book, the probability of collapse has a time-progress symmetry.
Now, physicists call the observed curve “the exponential decay law.” While we speculate that some external factors cause the nucleus to collapse randomly, the current orthodoxy is that it is simply random in itself. If an accidental process is implemented, it can be expected that there will be a preferred time distribution. We have no more reason to explain why the collapse occurs than why the fair coin has the same probability of falling to the front and to the back. A simpler conclusion is that there are no random elements in the universe that are invisible.
In this example, the exponential “rules” have time-progress symmetry. This is a rule of vacuum that does not have something characteristic over time. As we have already seen, the cosmological principles of physics can be named lawless laws of vacuum.
Why is something real?
Now, you’ll have this question. If the universe has the properties of a universal vacuum, why not a purely vacuum? The answer may be that vacuum is less stable than matter in space.
We often find cases in physics where a fairly symmetrical system is less stable than a less symmetrical system. This is because the system reacts to become a lower energy state, because the less symmetrical state has a lower energy level. A pencil standing at one end has rotational symmetry relative to its vertical axis, but it is unstable and falls from a light bounce.
Snowflakes can be another example. We are used to seeing snowflakes melt, but this is only because the temperature of the environment we live in is above the freezing point on average. The energy of the environment destroys its structure. When a snowflake is placed in an isolated vacuum, it lasts permanently in principle.
The vacuum is quite symmetrical, so we can expect to react spontaneously in a less symmetrical state. The calculations of well-made models support that fairly symmetrical states are generally unstable, not always.
Frank Wilczek, a Nobel Prize winner in physics, wrote the following, a fantastic summary of the picture I wanted to envision.
Modern theories of the interaction between underlying particles suggest that the universe can exist in many states, just as water can exist as a liquid or solid. The state of matter in various states is different; for example, certain particles are light in some states, but heavy in others. Just as the lattice arrangement is more symmetrical in water than in ice that determines a particular position and direction in space, the laws of physics are more symmetrical in this form now than they are in other states.
In these models, most symmetrical phases of the universe are found to be unstable. One can imagine that a universe that began in a mostly symmetrical state could exist, where there would be no matter at all. The second state is slightly less symmetrical, but the energy level is also low. Finally, the less symmetrical state grows fast. The energy released by the phase transition is found in the form of the formation of particles. This case can be confirmed in the form of the Big Bang. The fact that the universe of particles is electrically neutral is understandable because the universe in which matter is missing is also electrically neutral. The lack of rotation of the universe can be understood as being between the most suitable environment for phase transition and the subsequence growth, which includes the phenomenon of broken asymmetry between matter and antimatter. The ancient question, “Why is something real?” can be answered by “because nothing is unstable.”
How does this suggest that the universe came from nothing? The meaning of nothing can be the subject of endless discussion. How would you define radish? What are the characteristics of nothing before defining it? If nothing has any characteristic, why can’t it be anything else in the world? The philosopher Bede Rundle concluded in his book Why there is Something rather than Nothing.
I have also defined vacuum as a state in which you have removed all matter and energy. No physical quantities can be measured in a vacuum. The vacuum doesn’t react even if you kick it. If this vacuum isn’t a radish, I don’t really know what a radish is. If the vacuum is unstable, we define “real” as another state of nothing. As if ice and steam are different states of water.
Input: December 17, 2015 23:57