ما در نهایت از چه چیزی تشکیل شده ایم؟ بلوک های ساختمانی اساسی کیهان چیست؟

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 در حال چرخش 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 جهان. 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 جهان (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 جهان made up of? What are the fundamental building blocks of nature? And, what are the basic laws of nature governing everything in the جهان? مدل استاندارد 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 جهان.  

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 مدار. 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 جهان. However, with advances in science, this understanding too has seen changes. Fields are found to be fundamental and not particles.  

ذرات اساسی نیستند. آنچه اساسی است زمینه ای است که زیربنای آنهاست. همه ما از میدان های کوانتومی تشکیل شده ایم. 

As per current understanding of science, everything in the جهان 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 جهان 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 جهان, for example, magnetic and electrical fields are spread across the جهان. 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 جهان. 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 جهان 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 جهان.  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/فیلدهای ماده: The four basic quantum fields and their associated particles (viz., “electron”, “up quark”, “down quark” and “neutrino”) form the bedrock of the جهان. 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”.  

بنابراین، 12 میدان وجود دارد که باعث ایجاد ذرات می شود، ما آنها را می نامیم زمینه های ماده.

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

فیلدهای نیرو12 میدان ماده از طریق چهار نیروی مختلف با یکدیگر تعامل دارند - جاذبه زمین, الکترومغناطیس, نیروهای هسته ای قوی (فقط در مقیاس کوچک هسته عمل می کنند، کوارک ها را در داخل پروتون ها و نوترون ها کنار هم نگه می دارند) و نیروهای هسته ای ضعیف (فقط در مقیاس کوچک هسته، مسئول واپاشی رادیواکتیو و شروع همجوشی هسته ای عمل می کند). هر یک از این نیروها به یک میدان مرتبط است - نیروی الکترومغناطیسی مرتبط است میدان گلوئونمیدان های مرتبط با نیروهای هسته ای قوی و ضعیف هستند میدان بوزون W و Z و میدان مرتبط با گرانش است فضا-زمان خود.

در زیر لیستی از چهار میدان نیروی مرتبط با چهار نیرو آمده است.    

La جهان 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.  

میدان هیگز

In 1960s, one other field was predicted by Peter Higgs. By 1970s, this became integral part of our understanding about the جهان. 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 ثانیه صورت گرفت.  

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

ویژگی‌های ذرات (مانند بار الکتریکی و جرم) بیانیه‌ای درباره نحوه تعامل میدان‌های آنها با میدان‌های دیگر است.  

It is the interaction of the fields present in the جهان 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 جهان. Discovery of Higgs’s field was also confirmation of the Standard Model which was in place since 1970s.

میدان‌های کوانتومی و فیزیک ذرات رشته‌های مطالعاتی پویا هستند. از زمان کشف میدان هیگز، تحولات متعددی رخ داده است که با مدل استاندارد ارتباط دارد. تلاش برای یافتن پاسخ برای محدودیت های مدل استاندارد ادامه دارد.

*** 

منابع:  

The Royal Institution 2017. میدان های کوانتومی: بلوک های سازنده واقعی جهان – با دیوید تانگ. در دسترس آنلاین در https://www.youtube.com/watch?v=zNVQfWC_evg  

***