ממה אנחנו מורכבים בסופו של דבר? מהם אבני הבניין הבסיסיות של היקום?

Ancient people thought we are made up of four ‘elements’ – water, earth, fire and air; which we now know are not elements. Presently, there are some 118 elements. All elements are made up of atoms which were once thought to be indivisible. By early twentieth century following JJ Thompson’s and Rutherford’s discoveries, atoms were known to be constituted of nuclei (made of protons and neutrons) at the centre and electrons מסלול around. By 1970s, it was known that protons and neutrons are not fundamental either but are made up of ‘up quarks’ and ‘down quarks’ thus making ‘electrons’, ‘up quarks’ and ‘down quarks’ the three most fundamental constituents of everything in the עוֹלָם. With the pathbreaking developments in quantum physics, we learnt that particles are actually derivatives, the bundles or packets of energy in the fields implying particles are not fundamental. What is fundamental is field that underlies them. We can now say quantum fields are the fundamental building blocks of everything in the עוֹלָם (including advanced biological systems like us). We are all made up of quantum fields. Properties of particles like electric charge and mass, are statements about how their fields interact with other fields. For example, the property that we call electric charge of an electron is a statement about how the electrons field interacts with the electromagnetic field.  And. the property of its mass is the statement about how it interacts with the Higgs field.  

Since the ancient times, people have wondered what we are made up of? What is the עוֹלָם made up of? What are the fundamental building blocks of nature? And, what are the basic laws of nature governing everything in the עוֹלָם? דגם סטנדרטי of science is the theory that answers these questions. This is said to be the successful theory of science ever built over the last centuries, one single theory that explains most of the things in the עוֹלָם.  

People knew early that we are made up of elements. Each element, in turn, is made up of atoms. Initially, it was thought that atoms are indivisible. However, in 1897 JJ Thompson discovered electrons using electric discharge through cathode ray tube. Soon after, in 1908, his successor Rutherford proved through his famous gold foil experiment that an atom has a tiny positively charged nucleus at the centre around which negatively charged electrons circle in מסלולים. Subsequently, it was found that nuclei are made up of protons and neutrons.  

In 1970s, it was discovered that neutrons and protons are not indivisible hence not fundamental, but each proton and neutron are made up of three smaller particles called quarks which are of two types – “up quarks’’ and “down quarks’’ (“up quark” and “down quark” are merely different quarks. The terms ‘up’ and ‘down’ do not imply any relationship to direction or time). Protons are made up of two “up quarks’’ and a “down quark’’ while a neutron is made up of two “down quarks’’ and an “up quark’’. Thus, “electrons”, “up quarks” and “down quarks” are three most fundamental particles that are building blocks of everything in the עוֹלָם. However, with advances in science, this understanding too has seen changes. Fields are found to be fundamental and not particles.  

חלקיקים אינם בסיסיים. מה שעומד בבסיסו הוא התחום שעומד בבסיסם. כולנו מורכבים משדות קוונטיים. 

As per current understanding of science, everything in the עוֹלָם is made up of invisible abstract entities called ‘fields’ that represent the fundamental building blocks of nature. A field is something that is spread across עוֹלָם and takes a particular value at every point in space which can change with time. It is like ripples of fluid that sways throughout the עוֹלָם, for example, magnetic and electrical fields are spread across the עוֹלָם. Although we cannot see electric or magnetic fields, they are real and physical as evidenced by the force we feel when two magnets are brought closer. According to quantum mechanics, fields are thought to be continuous unlike energy that is always parcelled up in some discrete lumps.

Quantum field theory is the idea of combining quantum mechanics to fields. According to this, the electron fluid (viz. ripples of the waves of this fluid) get tied into little bundles of energy. These bundles of energy are what we call electrons. Thus, electrons are not fundamental. They are the waves of the same underlying field. Similarly, ripples of the two quark fields give rise to “up quarks” and “down quarks”. And the same is true of every other particle in the עוֹלָם. Fields underlie everything. What we think of as particles are actually waves of the fields tied up into little bundles of energy. The basic fundamental building blocks of our עוֹלָם are these fluid-like substances that we call fields. Particles are merely derivatives of these fields. In pure vacuum, when particles are taken out completely, fields still exist.   

Three most basic quantum fields in the nature are “electron”, “up quark”, and “down quark”. There is a fourth one called neutrino, however, they do not constitute us but play an important role elsewhere in the עוֹלָם.  Neutrinos are everywhere, they stream through everything everywhere without interacting.

https://www.scientificeuropean.co.uk/sciences/space/the-fast-radio-burst-frb-20220610a-originated-from-a-novel-source/שדות חומר: The four basic quantum fields and their associated particles (viz., “electron”, “up quark”, “down quark” and “neutrino”) form the bedrock of the עוֹלָם. For unknown reasons, these four fundamental particles reproduce themselves twice over. Electrons reproduce “muon” and “tau” (which are 200 times and 3000 times heavier than electrons respectively); up quarks give rise to “strange quark” and “bottom quark”; down quarks give rise to “charm quark” and “top quark”; while neutrino give rise to “muon neutrino” and “tau neutrino”.  

לפיכך, ישנם 12 שדות שמולידים חלקיקים, אנו קוראים להם שדות חומר.

Below is the list of 12 matter fields that make up 12 particles in the עוֹלָם.  

שדות כוח: 12 שדות החומר מקיימים אינטראקציה זה עם זה באמצעות ארבעה כוחות שונים - כוח משיכה, אלקטרומגנטיות, כוחות גרעיניים חזקים (פועלים רק בקנה מידה קטן של גרעין, מחזיק קווארקים יחד בתוך פרוטונים וניוטרונים) ו כוחות גרעיניים חלשים (פועלים רק בקנה מידה קטן של גרעין, אחראי להתפרקות רדיואקטיבית וליזום היתוך גרעיני). כל אחד מהכוחות הללו קשור לשדה - כוח אלקטרומגנטי קשור אליו שדה גלואון, שדות הקשורים לכוחות גרעיניים חזקים וחלשים הם שדה בוזון W ו-Z והשדה הקשור לכבידה הוא זמן חופשי עצמו.

להלן רשימה של ארבעה שדות כוח הקשורים לארבעה כוחות.    

אל האני עוֹלָם is filled with these 16 fields (12 matter fields plus 4 fields associated with four forces). These fields interact together in harmonious ways. For example, when the electron field (one of the matter fields), starts to wave up and down (because there is an electron there), that kicks off one of the other fields, say electro-magnetic field which, in turn, will also oscillate and ripple. There will be light which is emitted so that will oscillate a little. At some point, it will start interacting with the quark field, which in turn, will oscillate and ripple. The final picture we end up with, is the harmonious dance between all these fields, interlocking each other.  

שדה היגס

In 1960s, one other field was predicted by Peter Higgs. By 1970s, this became integral part of our understanding about the עוֹלָם. But there was no experimental evidence (meaning, if we make Higgs field ripple, we should see associated particle) until 2012 when CERN researchers at LHC reported its discovery. The particle behaved exactly the way predicted by the model. The Higgs particle has very short life, of about 10^-22 שניות.  

This was the final building block of the עוֹלָם. This discovery was important because this field is responsible for what we call mass in the עוֹלָם.  

תכונות של חלקיקים (כמו מטען חשמלי ומסה) הן הצהרות על האופן שבו השדות שלהם מתקשרים עם שדות אחרים.  

It is the interaction of the fields present in the עוֹלָם that give rise to properties such as mass, charge etc. of different particles experienced by us. For example, the property that we call electric charge of an electron is a statement about how the electrons field interacts with the electromagnetic field. Similarly, the property of its mass is the statement about how it interacts with the Higgs field.

An understanding of Higgs field was really needed so that we understood the meaning of mass in the עוֹלָם. Discovery of Higgs’s field was also confirmation of the Standard Model which was in place since 1970s.

שדות קוונטיים ופיזיקה של חלקיקים הם תחומי מחקר דינמיים. מאז גילוי השדה של היגס, התרחשו כמה פיתוחים שיש להם יחס לדגם הסטנדרטי. החיפוש אחר תשובות למגבלות המודל הסטנדרטי נמשך.

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מקורות:  

המוסד המלכותי 2017. שדות קוונטיים: אבני הבניין האמיתיות של היקום - עם דיוויד טונג. זמין באינטרנט ב https://www.youtube.com/watch?v=zNVQfWC_evg  

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