eBook - ePub
Abc Of Physics: A Very Brief Guide
A Very Brief Guide
Lev Okun
This is a test
Share book
- 168 pages
- English
- ePUB (mobile friendly)
- Available on iOS & Android
eBook - ePub
Abc Of Physics: A Very Brief Guide
A Very Brief Guide
Lev Okun
Book details
Book preview
Table of contents
Citations
About This Book
Translated from Russian by Vitaly Kisin
This little book concentrates on the foundations of modern physics (its “ABC's”) and its most fundamental constants: c — the velocity of light and ℏ — the quantum of action.
First of all, the book is addressed to professional physicists, but in order to achieve maximal concentration and clarity it uses the simplest (high school) mathematics. As a result many pages of the book will be useful to college students and may appeal to a more general audience.
Contents:
- The Fundamentals
- Units
- A Minimum of Mathematics
- Translational Motion
- Rotation and Quantization
- Particles as Corpuscles and Waves
- More About Units
- The Hydrogen Atom
- Periodic Table of Chemical Elements
- Substance
- Quantum Electrodynamics — QED
- Transition to Classical Theory
- Gravitation
- Other Galaxies
- Big Bang
- Quantum Gravidynamics — QGD
- Intranuclear Forces
- Particles in Cosmic Rays
- Particles in Accelerators
- Three Discrete Symmetries
- Half a Century Later
- On Quantum Chromodynamics
- On the Electroweak Theory
- Supersymmetry
- Grand Unification
- In the Vicinity of the Planck Mass
- Concluding Remarks
Readership: College students and interested readers in the physical sciences.
Frequently asked questions
How do I cancel my subscription?
Can/how do I download books?
At the moment all of our mobile-responsive ePub books are available to download via the app. Most of our PDFs are also available to download and we're working on making the final remaining ones downloadable now. Learn more here.
What is the difference between the pricing plans?
Both plans give you full access to the library and all of Perlegoās features. The only differences are the price and subscription period: With the annual plan youāll save around 30% compared to 12 months on the monthly plan.
What is Perlego?
We are an online textbook subscription service, where you can get access to an entire online library for less than the price of a single book per month. With over 1 million books across 1000+ topics, weāve got you covered! Learn more here.
Do you support text-to-speech?
Look out for the read-aloud symbol on your next book to see if you can listen to it. The read-aloud tool reads text aloud for you, highlighting the text as it is being read. You can pause it, speed it up and slow it down. Learn more here.
Is Abc Of Physics: A Very Brief Guide an online PDF/ePUB?
Yes, you can access Abc Of Physics: A Very Brief Guide by Lev Okun in PDF and/or ePUB format, as well as other popular books in Biological Sciences & Science General. We have over one million books available in our catalogue for you to explore.
Information
Chapter 1
The Fundamentals
1.1Ā Ā Ā Ā On intuition
The purpose of this book is to explain within a hundred-odd pages how modern elementary particle physics allows us to understand the workings of the surrounding world. Two universal constants lie at the basis of the cosmos: the maximum speed of uniform rectilinear motion c and minimum quantum of rotational and oscillatory motion ħ. The words ārectilinearā and āuniformā seem to point to unbounded, infinite motion through space and to linearity of the time (the philosophy of the Occident). Rotation points to cyclical nature of time and to bounded, finite nature of motion (the philosophy of the Orient).
The matter I wish to present here is not philosophy but the way in which physicists quantitatively describe their observations and experiments using intuition as their tool. The main problem of modern physics is that the concepts of maximum speed and minimum quantum appear extremely anti-intuitive to those who do not work in fundamental physics.
1.2Ā Ā Ā Ā Space and time*
Our space is three-dimensional: any observer can imagine a system of coordinates ā three mutually orthogonal axes: back-to-forward (x), left-to-right (y), bottom-to-top (z). The observer typically places himself at the origin of coordinates.
Imagine an observer following the motion of a particle. He characterizes the position of the particle at the moment of time t by the radius vector r with its three coordinates: x, y, z. The coordinate system plus time form what we call the frame of reference. All points in space and time are equivalent: both space and time are uniform. In addition, space is isotropic: the three axes can be oriented in an arbitrary manner. Note that under such re-orientations the magnitude of the radius vector remains unchanged: r ā” |r| = const.
1.3Ā Ā Ā Ā Matter and substance*
Any change in the motion or behavior of a particle is a manifestation of elementary (i.e. the smallest and indivisible) particles of matter. We begin with three elementary particles of matter: the photon Ī³, the electron e and the proton p. We will first see how the simplest hydrogen atom emerges as a result of their interaction. We will then look at other atoms so as to understand how the matter around us emerges as a result of their interaction and formation of increasingly complex systems of interlinked particles. Then we will go deeper step by step and learn about all other elementary particles.
There is still no universally accepted definition of what should be called āsubstanceā and what should be called āmatterā. Many authors use the term āmaterial particleā only if the particle has nonzero mass. Suffice it to recall the term āmaterial pointā which is used in the literature by many authors (see e.g. Weinbergās book [1]) where they discussed āmassive pointsā, that is bodies whose size can be considered negligible in a specific problem. For these authors photons are particles of radiation, not of matter. The debate on what should be called which name will be solved some day. At the moment I will refer to all particles including photons as particles of matter. And I will call atoms and everything built of atoms as substance.
1.4Ā Ā Ā Ā Motion*
Motion is the displacement of a particle in space. If the motion is translational (i.e. uniform and rectilinear) then the velocity v of displacement is given by the formula v = r/t where r is the path covered and t is the time the displacement took. The definition of velocity in the case of arbitrary motion will be given a little later.
Chapter 2
Units*
2.1Ā Ā Ā Ā Standards
Every measurement is a comparison of what is being measured with a known standard. The generally accepted standards with which results of measurements are compared are called units.
2.2Ā Ā Ā Ā Circle and angles
Angles are measured in degrees (minutes and seconds) or in radians. One degree of arc is the angle subtended at the center of a circle by the arc obtained by dividing the circle into 360 equal parts. The minute of arc: 1ā²=1Ā°/60. The second of arc: 1ā³=1ā²/60. We know that the ratio of the circumference of the circle to its radius equals 2Ļ, where Ļ ā 3.14. One radian 1 rad= 360Ā°/2Ļ ā 57Ā° is the angle subtended by the arc whose length equals that of the radius.
2.3Ā Ā Ā Ā Units of time and length
Units of time are determined by the rotation of the Earth. A day and a night are 24 hours long. One hour = 60 minutes. One minute = 60 seconds. Although one hour and one degree of arc consist of 60 minutes and 3600 seconds, this is the only common feature between the units of angle and time.
Lengths are measured by comparing them against the established length standard. The meter is the typical unit for measuring lengths.
Chapter 3
A Minimum of Mathematics
Mathematics is often said to be the queen and a servant of all the natural sciences. But mathematics is also a powerful obstacle when people are introduced to these sciences. This is why authors of popular science books and articles avoid using mathematical notation. In my opinion, modern physics cannot be explained without mathematics. I will try to limit myself to a minimum of mathematical knowledge. But this minimum is necessary and unavoidable.
3.1 Four operations of school mathematics and the imaginary unit*
Two types of arithmetic operations will be needed here to reach understanding of the laws of nature: 1) addition/subtraction, 2) multiplication/division, and two types of algebraic operations: 3) raising to power and 4) finding the logarithm. It wonāt be soon that we will need this last operation. We will also need the concept of the imaginary unit and of complex numbers.
3.2 Powers of ten*
When studying nature, we constantly come across very large or very small numbers which are conveniently presented as powers of ten. Thus the speed of light is 3 Ā· 105 km/s = 3 Ā· 108 m/s, and the size of an atom is on the order of 10ā10 m. Unlike authors of popular science books, I will not use expressions like āone thousandth of one millionth ofā; I will write 10ā9.
3.3 Prefixes of the powers of ten
Many physical terms include the following prefixes:
Deca | 101 | da | Deci | 10ā1 | d |
Hecto | 102 | h | Centi | 10ā2 | c |
Kilo | 103 | k | Milli | 10ā3 | m |
Mega | 106 | M | Micro | 10ā6 | Ī¼ |
Giga | 109 | G | Nano | 10ā9 | n |
Tera | 1012 | T | Pico | 10ā12 | p |
Peta | 1015 | P | Femto | 10ā15 | f |
Exa | 1018 | E | Atto | 10ā18 | a |
Zetta | 1021 | Z | Zepto | 10ā21 | z |
Yotta | 1024 | Y | Yocto | 10ā24 | y |
3.4 Differentiation and integration
The velocity of arbitrary motion is determined as the derivative of distance with respect to time: v = dr/dt. The quantity dt stands for a sufficiently small (āinfinitely smallā) difference between two very close points in time. The quantity dr has a similar meaning ā the difference between two points in space very close to one another. Here the infinitely small distance between two points in space is divided by the infinitely short interval of time, which gives as a result the finite velocity of motion. This operation is called differentiation. Integration is an operation inverse to differentiation: r = ā« vdt.We wonāt need these operations just yet. It would be very useful to readers ā both familiar with the concepts of dif...