Chapters 10 and 11

Interaction and Empty Space Isn't Empty

• Quantum Electrodynamics is another important theory that helps explain how particles interact with each other
• Electrons can go backwards in time (when this happens they appear to be particles that have a positive charge)
• Empty space is potentially filled with Higgs boson particles and these particles give particles what we call mass because when other particles bump into the Higgs particle, they end up zigzagging throughout space. This zigzag is what gives particles mass.

Chapter 9: The Modern World

The main topic of this chapter is the Transistor and how it has changed the world since its invention in 1947.

Fun Facts about transistors:

• You can buy over 100,000 transistors for the cost of a single grain of rice
• There are over a billion transistors in one cell phone
• The amount of resistors manufactured in the world each year is one hundred times the total number of grains of rice consumed each year by the world's population

Jeff Forshaw and Brian Cox state that "it is probably not overstating things to say that the transistor is the most important invention of the last 100 years."

Logic gates are the reason why transistors have changed the world. A logic gate has the ability to take two inputs and generate one output.

Here is a rather long video that goes into great depth about logic gates and transistors.

Here is a video that is about half as long (its still 15 minutes though so it is obvious that this topic is quite complicated and requires some time a patience to explain)

The gist of it all is that transistors are able to take two inputs and generate one output. These outputs generally are 1 or 0. Sound familiar?  This is one of the ways that quantum physics has transformed the world.

Chapter 8: Interconnected

Interesting tidbits from Interconnected:

"every electron in the Universe knows about the state of every other electron. WE need not stop there- protons and neutrons are fermions too, and so every proton knows about every other proton and every neutron knows about every other neutron. There is an intimacy between the particles that make up our Universe that extends across the entire Universe."

So our Universe truly is completely interconnected and even though we can't see these tiny components that make up our Universe, they are really there, all interconnected, creating the world the way we see it everyday. It is so incredible to think about these ideas. Our knowledge of quantum mechanics really has changed the way we humans see everything.

Fixed currents are the result of an average energy level that electrons are at. Electrons jump up to higher energy levels and drop down to lower energy levels due to imperfections and movement in atoms. However, an "average" energy level is maintained resulting in a current that follows ohm's law (V=IR).

Chapters 6 and 7

Interesting tidbits from The Music of the Atoms:

• Standing waves are waves whose peaks and troughs are always in the same place. They rise and fall, but they always stay in the same place

An electron can have many different energies at the same time

Electrons do not constantly emit photons of light because they can't. Electrons are only able to release energy (in the form of photons) in "large chunks".

Coulomb's potential well depicts the different energy levels an electron can be at

Interesting tidbits from The Universe in a Pin-Head (and Why We Don't Fall Through the Floor):

• It is possible that the entire universe was once the size of the head of a pin
• Yet another flashback to sophomore chemistry: quantum numbers n, l, and m
• Spin quantum number is based on the idea that electrons spin and are therefore affected by magnetic fields (a subject interestingly enough discussed in physics last week) depending on how they are oriented in relation to the field
• Fermions vs bosons: the difference is in the spin (a measure of amgular momentum of a particle)

Chapters 4 and 5

Interesting tidbits from Everything That Can Happen Does Happen:

• Teleological ideas are ideas that "appear to happen in order to achieve a pre-specified outcome"
• Action is m(x^2)/t where m is mass, x is distance and t is time
• Leonard Euler found that a ball, when thrown, traverses the path that minimizes its action
• Heisenberg's Uncertainty Principle:

"The more precisely you know the position if a particle at some instant, the less well you know how fast it is moving and therefore where it will be sometime later."

Other interesting tidbits from Movement as an Illusion:

• Another flashback to sophomore chemistry: de Broglie's equation ("the wave-particle duality of quantum mechanics")
•  It is more acurate to describe motion as the summation of the infiniate paths a particle travels to get from point a to point b

Chapter 3: What Is a Particle?

Subatomic particles, according to Richard Feynman, "do not behave like waves, they do not behave like particles, they do not behave like clouds, or billiard balls, or weights on springs, or like anything that you have ever seen." So I am confused; what on earth do subatomic particles act like? I don't really know, and it seems that Richard Feynman thinks its ok for me to feel this way.

Brian Cox and Jeff Forshaw however, are attempting to explain to me exactly how subatomic particles act in this chapter. The craziest piece of knowledge that I gained from this chapter is that quantum particles can be in many places all at once. 

An important part of this chapter is the famous double slit experiment. Here is what is said about the path of an electron traveling in an electron wave through the double slits onto a screen.

The correct answer to the question 'how did that electron get to the screen' is 'it traveled by an infinity of possible routes, some of which went through the upper slit and some of which went through the lower one'.

So essentially, quantum particles can be in more than one place at a time and electrons can travel many different paths at once. My mind is yet again blown. This stuff is pretty cool (and cool is not a very good adjective to describe this).

Here's one more great quote from this chapter:

Nature really does use random numbers, and the loss of certainty in predicting the positions of particles in an intrinsic property of the physical world: probabilities are the best we can do. 

Chapter 2: Being in Two Places at Once

This chapter took me back to the early days of sophomore chemistry with Niels Henrik David Bohr and his lovely atomic model.

Bohr's model specifies the orbitals that electrons orbit in around the nucleus of the atom. It is in the jumping between these orbitals that photons of light are emitted. The next development in the history of quantum physics came from Heisenberg, whose uncertainty principle continues to baffle me. Essentially, Heisenberg was saying that quantum theory doesn't necessarily correspond with ideas familiar to us.

There have been several points while reading this book that I have had to put it down and take a step back just because the words on these pages are explaining concepts that are so foreign to me, and make me think in such different ways about the world I live in. The conclusion of this chapter presented one of these moments. Cox and Forshaw say that a scientist living in a cave underground, without having ever seen the sun, would have been able to develop the quantum theory. And upon doing this, they could have calculated the "maximum mass of a giant sphere of gas". A scientist named Subrahmanyan Chandrasekhar calculated the maximum mass of a white dwarf star (the same as the maximum mass of a giant sphere of gas) in 1930 and if you observe the stars today, there is not a single star that's mass exceeds the Chandrasekhar limit. I just think that that is so cool!

Chapter 1: Something Strange Is Afoot...

In terms of all of the writing I have been doing about the definition of science in terms of different philosophers, this quote from the first page of this book captures the essence of the definition of science in my opinion:

"Science, of course, has no brief to be useful, but many of the technological and social changes that have revolutionized our lives have arisen out of fundamental research carried out by modern-day explorers whose only motivation is to better understand the world around them."

The first chapter lays the basis for Quantum theory, the rules of which can apparently fit "on the back on an envelope." In relation to the quote above, the authors make it clear that Quantum theory is the result of some scientists trying to understand the world on a subatomic level.

Max Planck apparently was the first to use the world "quantum" in 1900. He was working with black body radiation, and he called the little packets of energy that made up light "quanta". The beginning of Quantum theory, it seems, lies in the study of light, and more specifically, stems from the point at which scientists realized that light  has characteristics of both a wave and a particle.

An Initial Note

This blog is a compilation of my thoughts on the numerous interesting topics covered in The Quantum Universe written by Brian Cox and Jeff Forshaw. Here is the Amazon.com page for this book!