Day3 of #Quantum30 Challenge
Well, first of all, kudos to me for showing up on Day 3 of this exciting challenge. Being a Physics student myself, I have always been dazzled by the mysteries of our Universe. The lecture resource for Day 3 was nothing but an astonishing attempt to showcase the beauty of science to the general audience.
The beautiful lecture, “Quantum Fields: The Real Building Blocks of the Universe — with David Tong” on the YouTube channel The Royal Institution. The speaker starts the discussion with a fundamental question in science: What are the fundamental building blocks of nature? This question has been explored for over two and a half thousand years, from ancient Greek times to the present. The talk aims to provide an overview of our current understanding and future prospects. The discussion covers topics such as experiments at the Large Hadron Collider (LHC) in CERN, which explore particle physics, and experiments looking back in time towards the Big Bang. The speaker, a theoretical physicist, also delves into abstract ideas and the mathematics that underlie our understanding of the universe. The periodic table of elements is mentioned as a significant milestone in our understanding of matter, with approximately 120 elements believed to constitute everything in nature during the 1800s. The talk celebrates the progress and achievements of science in exploring the composition of the universe. The speaker jokes about how the periodic table of elements looks similar to Australia and how the periodic table is kind of a silly way to organize the basic building blocks of nature.
The speaker discusses the progression of our understanding of the fundamental building blocks of nature. Initially, the periodic table of elements was thought to represent the fundamental constituents of matter. However, J.J. Thomson’s discovery of the electron in the late 1800s challenged this notion. Ernest Rutherford later proposed a model of the atom, revealing a nucleus with electrons orbiting around it. Further investigations revealed that the nucleus is composed of protons and neutrons, and inside these particles are even smaller entities called quarks. Quarks come in two types: up quarks and down quarks. Protons consist of two up quarks and a down quark, while neutrons consist of two down quarks and an up quark. This progression highlights our ongoing exploration of the fundamental components of the universe.
It’s an amazing lesson to learn about how the world is put together. We have an electron and two quarks. The speaker emphasizes that the current understanding of the fundamental building blocks of nature has evolved. While traditional teaching suggests electrons and quarks as the elementary particles, it is now known that the best theories of physics do not rely on particles at all. Instead, the fundamental reality is described by fluid-like substances called fields, which are spread throughout the entire universe and exhibit interesting ripples. Fields are something that has a specific value at each point in space. These abstract and nebulous fields form the true basis of nature, unlike the simplistic particle model often taught in schools. Fields represent a more advanced and accurate description of the universe’s fundamental constituents.
The idea of fields as fundamental entities is not new and dates back almost 200 years, originating from the work of Michael Faraday, who conducted experiments on electricity and magnetism. Faraday’s intuition led him to propose the existence of electric and magnetic fields, invisible objects that pervade all of space. This idea was groundbreaking and revolutionary in the history of science. Faraday’s genius was to realize that even though these fields are invisible, they are real and physical, responsible for forces like the pressure between magnets. He visualized them as “lines of force” and referred to them as the electric and magnetic fields, which we still use in modern physics to describe the fundamental aspects of nature.
Michael Faraday’s experiments on electricity and magnetism led to his discovery of induction, where a moving magnetic field generates a current in a nearby coil, showcasing the reality of fields. This notion astounded audiences in the 1800s since it demonstrated that fields could influence objects from a distance without physical contact. Faraday’s work showed that nature involves more than just particles; there are also fields, which are subtle objects spread throughout space. His ideas later played a crucial role in understanding light as ripples in electric and magnetic fields.
Over the next 150 years, the concept of fields gained even greater importance. In the 1920s, scientific advancements revealed that the world operates differently from the classical Newtonian and Galilean ideas, prompting a small revolution in science. In the 1920s, scientists like Heisenberg and Schrodinger discovered that the world behaves in mysterious and counterintuitive ways at microscopic scales, leading to the theory of quantum mechanics. Quantum mechanics revealed that energy is not continuous but rather comes in discrete packets called quanta. To reconcile quantum mechanics with Faraday’s ideas of continuous fields, scientists developed quantum field theory.
According to quantum field theory, the electromagnetic field, which gives rise to light waves, is not entirely continuous. Instead, light waves are made up of particles known as photons. Similarly, every particle in the universe, such as electrons and quarks, corresponds to ripples or waves in underlying fields. These fields permeate everything, connecting all particles in the universe. Thus, what we perceive as particles are actually wave-like bundles of energy in these fields.
This vision, inspired by Faraday’s work, challenges the traditional notion of particles as the fundamental building blocks of the universe. Instead, it asserts that the universe is composed of fluid-like fields, leading to a deeper understanding of our existence and connection to the world.
In the pursuit of understanding the universe, we start by considering the simplest scenario: an empty box, where every single particle and atom has been removed, leaving only a pure vacuum. Surprisingly, even in this seemingly empty space, something profound is happening. The vacuum is not dull but a place filled with fields that are governed by the rules of quantum mechanics.
According to the Heisenberg Uncertainty Principle, even in the vacuum, these fields can’t sit still. They constantly fluctuate and bubble in a complex manner, known as quantum vacuum fluctuations. This phenomenon is a direct consequence of the principles of quantum mechanics.
Quantum vacuum fluctuations are not just theoretical concepts; they have practical implications. For instance, the Casimir force, a real measurable force, is a result of these fluctuations between metal plates being pushed together due to more quantum activity on the outside than the inside.
However, understanding and describing these quantum fields is incredibly challenging. Even the simplest scenario of the vacuum turns out to be astonishingly complicated mathematically. This complexity increases exponentially when trying to describe particles or systems with many particles. The mathematics involved in describing quantum fields is significantly more difficult than other areas of physics or science, presenting a major challenge for researchers in the field.
In the realm of mathematics, there are six notoriously challenging open problems, considered the hardest in the field. These problems include the Riemann hypothesis and P versus NP, among others. Understanding the quantum fluctuations within the vacuum is comparable to these difficult problems, and a solution to it could earn someone a million-dollar prize. Unlike merely demonstrating these fluctuations with a computer, the challenge lies in grasping the patterns emerging from these quantum fluctuations by solving the underlying equations. The complexity of this problem makes it extremely rare for researchers to work on it.
The talk now shifts to discussing the mathematical challenges in quantum field theory, which describes the behavior of quantum fields in our universe. In certain scenarios, such as when quantum fluctuations are calm and tame, we have a good understanding of what happens. However, when fluctuations become wild and strong, our mathematical comprehension becomes limited. An example is provided with the property “g” of the electron, which determines the speed of the electron’s spin-axis procession in the presence of a magnetic field. Accurate measurements of “g” through experiments have been instrumental in testing our understanding of quantum field theories and nature’s underlying principles.
The speaker presents two remarkable numbers: one from precise experimental measurements and the other from challenging theoretical calculations. These numbers represent the magnetic moment of an electron and demonstrate an extraordinary agreement between theory and experiment, with an accuracy of about 12 or 13 significant figures. This level of agreement is unparalleled in any other scientific field.
However, the situation becomes more challenging when dealing with stronger quantum vacuum fluctuations. For instance, calculating the mass of a proton theoretically has proved difficult, despite having the correct equations. While we have made progress and reached around 3% accuracy, it falls short of what we should achieve. In some cases, we face even more significant difficulties and lack an understanding of certain situations.
Theoretical physics has provided us with the best theories we have, but there is still much we don’t understand about quantum fields. The talk emphasizes the balancing act between advancing theoretical understanding and applying it to experiments. Ultimately, the message conveyed is that everything, including us, is made of quantum fields, but there is still much more to unravel and comprehend.
In this part of the talk, the speaker presents a new periodic table that outlines all the fundamental particles and their corresponding quantum fields in the universe. The four primary particles are the electron and the two quarks (up and down quarks), with the neutrino playing a distinct role elsewhere in the universe.
However, nature has a mysterious aspect as it reproduces these particles twice over. Alongside the electron, there are two other particles called the muon and the tau, which are heavier versions of the electron. Additionally, there are two more neutrinos, making a total of three. Moreover, the two original quarks (up and down) are accompanied by four other quarks, namely the strange quark, the charmed quark, the bottom quark, and the top quark.
The explanation for the doubling of these particles is well understood in one direction, but it remains a mystery in the other direction. Nonetheless, these 12 particles, or 12 fields, make up everything in the universe, including all known matter.
In the universe, there are 12 fundamental fields known as matter fields and four fields associated with forces. The matter fields include the electron and two quarks, while the forces are gravity, electromagnetism, strong nuclear force, and weak nuclear force.Einstein’s great insight was that the field associated with gravity is space and time itself, which is explained in general relativity. Together, these 16 fields interact and create the dance of the universe, with oscillations and ripples propagating through the interconnected fields.
The pinnacle of science is the theory that describes these fields and their interactions, known as the standard model. It’s considered the greatest theory in the history of human civilization. Additionally, there’s another field known as the Higgs field, proposed by Peter Higgs in the 1960s, which became an essential part of our understanding of the universe.
In 2012, experimental evidence at the Large Hadron Collider (LHC) confirmed the existence of the Higgs Field, a crucial component in the standard model of physics. The Higgs particle, associated with this field, is responsible for providing mass to particles in the universe. Its discovery was significant, not only for understanding mass but also for validating the standard model, a theory that has been around since the 1970s and predicted the Higgs particle back in the 1960s.
While the equation representing the standard model may look complex, it is a fundamental equation that encompasses all the results from experiments in science. It stands as the pinnacle of the reductionist approach to understanding the universe and plays a vital role in explaining interactions between fields and particles, including gravity, described by the first term in the equation.
The equation of the standard model of physics is a powerful tool that witha little part can explain a wide range of phenomena, from how apples fall from trees to the orbits of planets around the sun, and even the collision of black holes and the expansion of the universe. It encompasses gravity, electromagnetism, the strong and weak nuclear forces, and the interactions of particles with the Higgs field. It has been incredibly successful in explaining all experiments on Earth.
However, despite its success, there are still mysteries in the universe. Observations of space reveal invisible particles known as dark matter and dark energy, which remain unexplained by the standard model. Additionally, the rapid expansion of the universe during its early phase, known as inflation, is not accounted for in the equation. Scientists are eager to improve upon the standard model to understand these enigmatic aspects of the cosmos.
To move forward in understanding the universe and to explore laws of physics beyond the standard model, scientists need to tackle several mysteries. One of these is inflation, a period of rapid expansion shortly after the Big Bang. The universe was filled with a fireball for the first 380,000 years, and we have observed this through the cosmic microwave background radiation. The flickering in this fireball was caused by quantum vacuum fluctuations that occurred in the first fractions of a second after the Big Bang. As the universe expanded, these fluctuations stretched across the sky and left ripples in the fireball, which we can still observe today. The astonishing part is that these tiny quantum fluctuations have now become stretched across the entire universe, and their calculations perfectly match the observed data. Understanding such phenomena is crucial for unraveling the deeper mysteries of the cosmos.
One of the great successes of quantum field theory is its ability to explain phenomena like the fluctuations in the early universe, as observed in the cosmic microwave background radiation. However, the exact field responsible for these fluctuations remains unknown. Scientists are working to improve our understanding by studying the polarisation of the light from the fireball.
Moving forward, the Large Hadron Collider (LHC) is a crucial tool in the search for new physics beyond the standard model. The LHC discovered the Higgs boson in 2012 and has since undergone an upgrade. Scientists hope to find patterns in the equations of the standard model that could suggest deeper underlying structures or even the unification of forces.
For example, the equations for electricity and magnetism closely resemble those for the strong and weak nuclear forces. This similarity raises the possibility that these forces might be different aspects of a single, more fundamental force, and that our perception of three distinct forces is merely a perspective issue. Through experiments at the LHC and theoretical investigations, scientists are actively seeking new physics to advance our understanding of the universe.
The concept of unification suggests that the three forces in the universe (electromagnetism, strong nuclear force, and weak nuclear force) might actually be different aspects of a single, more fundamental force. This idea is known as grand unification. Similarly, the 12 matter fields (neutrinos, electrons, and quarks) may be different manifestations of the same underlying field, possibly through a theory called supersymmetry.
Another ambitious idea is to combine all the forces, particles, and fields into one simple concept, and this is the essence of string theory. These theoretical ideas have driven physics for decades, but the key question is whether they are correct. The Large Hadron Collider (LHC) was built to explore these possibilities, but despite running smoothly for two years, it has not yet provided evidence for any of these new ideas.
As scientists ponder how to progress in understanding the next layer of physics when experimental data doesn’t align with theoretical predictions, there is a sense of uncertainty and a need for new approaches. The lack of significant findings at the LHC has left many researchers searching for answers and potential new avenues of exploration.
There are three main responses to the lack of significant findings at the Large Hadron Collider (LHC) in the search for new physics beyond the standard model.
1. Some researchers argue for patience, suggesting that discoveries may still come in the future. They hope that the LHC will eventually reveal something new and lead to a deeper understanding of reality.
2. Another response is to propose building a larger and more powerful machine than the LHC to explore further. However, such an endeavor would require substantial funding, and currently, China is a potential candidate for hosting such a machine.
3. The third response, which the speaker personally supports, involves a more critical examination of the existing standard model equation. They believe that despite its correctness, there are still mysterious aspects that need to be understood better. They speculate that by delving deeper into the current equation, new patterns and insights may emerge.
It’s important to note that these responses are not universally agreed upon in the scientific community, and the search for new physics beyond the standard model remains a challenging and uncertain endeavor.
The speaker believes that there are hints in the current equation that point to unexplored mathematical patterns and connections to other areas of science, such as condensed matter physics and quantum information science. They are optimistic that with a fresh perspective, progress can still be made, even if it does not align with previous expectations. The goal is to eventually find something better than the current equation and advance our understanding of the universe.
Thank you for taking the time to read my complete and very long summary. I appreciate your attention and effort!
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