I address myself to the organization, founded for the purpose to further co-operation between nations on all problems of common concern, with some considerations regarding the adjustment of international relations required by modern development of science and technology. At the same time as this development holds out such great promises for the improvement of human welfare it has, in placing formidable means of destruction in the hands of man, presented our whole civilization with a most serious challenge. Open Letter to the United Nations by Niels Bohr

The United Nations is an international organization founded in 1945 after the second world war. The organization has four main goals:

  1. To keep peace throughout the world;
  2. To develop friendly relations among nations;
  3. To help nations work together to improve the lives of poor people, to conquer hunger, disease and illiteracy, and to encourage respect for each other’s rights and freedoms;
  4. To be a centre for harmonizing the actions of nations to achieve these goals.

When the United Nations first formed, there was only fifty-one countries in the organization. Today there is 193.

The development of atomic warfare would take huge steps forward at the turn of the 20th century:

In the early 1900’s, huge advancements in Atomic Physics took place. One of these is when Bohr concluded that breaking down the nucleus of an atom could release atomic energy. In 1934, Enrico Fermi was able to break down atoms by spraying them with neutrons; a similar experiment occurred in 1938 when Otto Hahn and Fritz Strassman broke down an uranium atom, turning atoms into energy. Not only did this lead to the development of atomic bombs, but it also proved Einstein’s mass-energy equivalence forumla, E=MC2.

With these scientific discoveries and Germany’s nuclear program already in development, Einstein wrote a letter to President Roosevelt in 1939 asking him to start a nuclear program. However, Einstein would come to regret this decision, stating:

I made one great mistake in my life, when I signed the letter to President Roosevelt recommending that atoms bombs be made.

This letter led to what is known as the Manhattan Project. The Manhattan Project was a research project that was funded over $2 billion dollars in order to figure out how to build an atomic bomb. One of the scientists who worked on this project was Bohr himself. The project started in 1942, and in 1945, the first atomic bomb would be used.

On August 6th, 1945, an American plane dropped an atomic bomb, dubbed Little Boy, on Hiroshima, Japan. Only three days later, another atomic bomb, named Fat Man, would be dropped on Nagasaki, Japan. These two bombs killed over 215,000 people, many of the casualties being civilians.

Mushroom cloud over Nagasaki.

Destruction as a result of the bombs.

A post-war model of Little Boy.

It is very important to note that many scientists didn’t want the atomic bomb to built as a means of catastrophic destruction, but rather to reap the many benefits of being able to build one and the knowledge that comes with it.

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So here's a quote from Niels Bohr, who is the famous
physicist who discovered the structure of that.
And he talks about how quantum mechanics is a very
counterintuitive theory. And anyone who's not
shocked by quantum mechanics has not understood it.
Another way of understanding this quote is that,
if you really want to deeply understand quantum
mechanics, then you have to grapple with the quantum
counterintuitive aspects of the theory. And so for those of
you who haven't really studied quantum mechanics before,
this way of approaching it, this emphasis on the one simple
systems, which illustrate the most counterintuitive
aspects of the theory, this might be the right way to
start studying the subject.
Introduction by Umesh Vazirani (Ft. Berkeley & University of California)

Niehls Bohr a famous physicist from the early 20th century known for his contribution to Atomic Theory. In 1913, Bohr took Max Planck’s idea that light energy is absorbed and given off in discrete amounts of quanta, and incorporated it into his model of the atom, known as the Bohr Model.

The Bohr Model answered a few unanswered question about Atomic Theory:

  1. Using Planck’s ideas, Bohr explained that electrons have a fixed orbit around the nucleus due to constant angular momentum and energy.
  2. The energy of the electron is related to it’s orbit; the electron with the lowest amount of energy has the smallest orbit.
  3. An electron can transition between the fixed orbits, known as quantum leaps, as radiation is absorbed or emitted.

Here is a more simplified diagram of the Bohr Model.

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And this brings me to the other part
of the course, which is an introduction to quantum mechanics.
Now the way we'll study quantum mechanics in this course
is in terms of a very simple building block, which comes
from quantum computation, which is that of a qubit.
So just as a bit, it's the simplest representation
of information in the classical world. A qubit is the
simplest quantum system that we can think of. And describing
quantum mechanics, the basic principles of quantum mechanics,
in terms of qubits, greatly simplifies the presentation.
Introduction by Umesh Vazirani (Ft. Berkeley & University of California)

I go into more detail about quibits in this annotation.


To summarize what a quibit is:

  • A quibit is a much more powerful bit; a bit is the basic form of information in computers today.
  • The reason they are much more powerful is that bits can only have two values, 0 or 1, while quibits can have a value of 0, 1, or a superposition of 0 or 1 — which means the quibit’s value can be in between 0 or 1. Since a quibit can have more values than a regular bit, it’s processing power is far superior.
  • A quibit is a physical system of discrete matter such as electrons, photons, ions, etc.

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UMESH VAZIRANI: Hello.
I'm Umesh Vazirani at UC Berkeley.
And I'm delighted to welcome you to this course
on Quantum Mechanics and Quantum Computation.
I'm sure many of you know that quantum computation
starts with this remarkable discovery that quantum
systems are exponentially powerful. So a major goal
of quantum computation is to harness this exponential power
to solve interesting computation problems. So in this
overview I want to tell you about what you can expect
to learn from this course, and how this course is organized.
Introduction by Umesh Vazirani (Ft. Berkeley & University of California)

Quantum computation is a field in which quantum theory is applied to computers. This field of study has drawn the interest of scientists due to how powerful quantum computer hardware can be.

In today’s world, computers are constantly being improved to meet the demands of the people. According to Moore’s Law, the number of transistors on microprocessors will double every eighteen months. This means that between 2020-2030, the circuits on a microprocessor will be on an atomic scale. Taking the power of molecules and atoms, and putting that power into computer hardware would be far more powerful than any of today’s silicon-based computer.


What makes quantum computers more powerful than today’s computers?

Today’s computers can only encode bits of information in one of two states (0 or 1). Quantum computers on the other hand, aren’t limited to only two states, it can use quibits — which are atoms, electrons, etc. working together as a computer processor, to encode information in a superposition — which is any number between 0 and 1. Since a quantum-based computer can encode information in many states simultaneously, it has the ability to process a million different computations at once. Another benefit of quibits are their ability to use complex algorithms that regular bits can’t.

If you want to read more on quantum computation, click here.

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On a whim, Showalter looked far beyond the ring segments and noticed the white dot about 65,400 miles from Neptune, located between the orbits of the Neptunian moons Larissa and Proteus. The dot is S/2004 N 1. Showalter plotted a circular orbit for the moon, which completes one revolution around Neptune every 23 hours. NASA Hubble Finds New Neptune Moon by National Aeronautics and Space Administration (NASA)

Along with S/2004 N 1, Larissa and Proteus have a short revolution orbit, with Larissa’s being a little over 13 hours, and Proteus being 27 hours.

Some more information on Larissa and Proteus:

Larissa and Proteus have a very similar topography with both of them being irregularly-shaped and heavily cratered, however Proteus is much larger.


Larissa is located roughly 45,700 miles away from Neptune. This moon is thought to be slowly spiraling inward, in which it will be broken apart by Neptune’s atmosphere.

Proteus is 73,100 miles away from Neptune. It is one of the darkest objects in our solar system; it reflects only 6% of light due to the neutral color of it’s surface.

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Mark Showalter of the SETI Institute in Mountain View, Calif., found the moon July 1, while studying the faint arcs, or segments of rings, around Neptune. "The moons and arcs orbit very quickly, so we had to devise a way to follow their motion in order to bring out the details of the system," he said. "It's the same reason a sports photographer tracks a running athlete -- the athlete stays in focus, but the background blurs." NASA Hubble Finds New Neptune Moon by National Aeronautics and Space Administration (NASA)

Neptune has five rings ranging from a composition of dust between 20-70% dust, with the rest being made up of small rocks. They are thought be the remains of a destroyed moon(s). The rings named on astronomers who made a discovery involving the planet. In order from nearest to farthest, the order of Neptune’s rings go:

  1. Galle Ring — Named after Gottfried Galle, the first person to see the telescope using a telescope. It is 41,000-43,000 km from Neptune.
  2. La Verrier Ring — This ring is named after the man who predicted Neptune’s position. This ring is narrow, only about 113 km wide.
  3. Lasell Ring — Named after William Lasell, this ring is the widest of all the rings at 4,000 km. It is 53,200-57,200 km away from Neptune
  4. Arago Ring — This ring is 57,200 miles from Neptune and is less than 100 km wide.
  5. Adams Ring — Named after the co-discoverer of Neptune, John Couch Adams, and only being 35 km wide, this ring is the most famous of them all due to it’s arcs. There are five arcs:
  6. Fraternité
  7. Égalité 1 and 2
  8. Liberté
  9. Courage

Here is a diagram labeling the rings along with some of Neptune’s larger moons.

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It even escaped detection by NASA's Voyager 2 spacecraft, which flew past Neptune in 1989 and surveyed the planet's system of moons and rings. NASA Hubble Finds New Neptune Moon by National Aeronautics and Space Administration (NASA)

Voyager 2’s was a spacecraft launched back in 1977 as a backup toVoyager 1, but it also served the purpose of collecting data from Jupiter, Saturn, Uranus, and Neptune.

Some of the data Voyager 2 collected include:

  • Voyager 2 took images of Jupiter and it’s rings. It also discovered numerous volcanoes on the moon Io, the possibility of an ocean under the ice crust of Europa, and the possibility of plate tectonics on Ganymede.

  • Voyager 2 was able to get close images of some of Saturn’s moons such as Enceladus, Hyperion, and Phoebe. The spacecraft also took pictures of the jet streams and storms in Saturn’s atmosphere.

  • Voyager 2 discovered ten new moons that orbit Uranus. It also took pictures of the moon, Miranda, and Uranus' atmosphere.

  • Lastly, Voyager 2 visited Neptune. At Neptune, Voyager 2 analyzed Neptune’s north pole, determined characteristics of Neptune and one of it’s moons, Triton, and discovered six new moons and three rings.

Today, Voyager 2 is studying the Heliosheath and the Heliopause, which is where solar wind stops, and interstellar space starts.

Fun Fact:

Voyager 2 carries an audio-visual disc just in case the spacecraft comes into contact with other intelligent life-forms. The disc contains pictures of Earth, greetings from political figures, and Sounds of Earth.

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The moon, designated S/2004 N 1, is estimated to be no more than 12 miles across, making it the smallest known moon in the Neptunian system. It is so small and dim that it is roughly 100 million times fainter than the faintest star that can be seen with the naked eye NASA Hubble Finds New Neptune Moon by National Aeronautics and Space Administration (NASA)

In comparison to all of Neptune’s other moons, S/2004 N 1 is small. In order of largest to smallest, the moons of Neptune go like this:

  1. Triton — 2,705 km
  2. Proteus — 420 km
  3. Nereid — 340 km
  4. Larissa — 200 km
  5. Despina — 160 km
  6. Galatea — 140 km
  7. Thalassa — 90 km
  8. Halimede — 60 km
  9. Neso — 60 km
  10. Naiad — 50 km
  11. Laomedia — 38 km
  12. Psamathe — 38 km
  13. Sao — 38 km
  14. S/2004 N 1 — 19 km

Links to the moon’s respective wikis can be found in the first annotation.

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NASA's Hubble Space Telescope has discovered a new moon orbiting the distant blue-green planet Neptune, the 14th known to be circling the giant planet. NASA Hubble Finds New Neptune Moon by National Aeronautics and Space Administration (NASA)

Excluding S/2004 N 1, the rest of Neptune’s are named as followed:

  1. Naiad
  2. Thalassa
  3. Despina
  4. Galatea
  5. Larissa
  6. Proteus
  7. Triton
  8. Nereid
  9. Halimede
  10. Sao
  11. Laomedeia
  12. Psamathe
  13. Neso

The blue-green color of Neptune is a result of the methane in the upper atmosphere absorbing red light and letting the blue end of the spectrum to bounce back out.

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The observations of NGC 2392 were part of a study of three planetary nebulas with hot gas in their center. The Chandra data show that NGC 2392 has unusually high levels of X-ray emission compared to the other two. This leads researchers to deduce that there is an unseen companion to the hot central star in NGC 2392. The interaction between a pair of binary stars could explain the elevated X-ray emission found there. A Beautiful End to a Star’s Life by National Aeronautics and Space Administration (NASA)

A binary star is a pair of stars orbiting around their common center of mass. One star in a binary system is known as the donor — usually a regular star — while the other star is known as the accretor — usually a white dwarf (such as this case), black hole, or neutron star.

Since the Eskimo Nebula is emitting a relatively high amount of electromagnetic radiation, it must be part of an X-ray binary system. To be even more specific, it might be a High-mass X-ray binary system in which a massive star produces solar wind and the accretor captures the solar wind and produces it as X-Ray emissions.

Although it is rather peculiar that the donor star would go undetected since they are usually very luminous and produce a lot of optical light.

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