[analogfilter]

More than ninety per cent of the universe is composed of hydrogen and helium. Both elements have been around since shortly after the beginning of the universe. Yet, hydrogen and helium together won't make anything as complex and as interesting as the earth, or a bacterium, or a refrigerator, or you and I. To do that we need carbon and oxygen and nitrogen and silicon and chlorine and every other naturally occurring element. Almost all the hydrogen and helium present in the universe today (and some of the lithium) were created in the first three minutes after the big bang. All of the other naturally occurring elements were created in stars.

[analogfilter]

You, are stardust

Lawrence Krauss

[analogfilter]

Dune, 1984

[analogfilter]

Archimedes

The most widely known anecdote about Archimedes tells of how he invented a method for determining the volume of an object with an irregular shape. According to Vitruvius, a votive crown for a temple had been made for King Hiero II, who had supplied the pure gold to be used, and Archimedes was asked to determine whether some silver had been substituted by the dishonest goldsmith. Archimedes had to solve the problem without damaging the crown, so he could not melt it down into a regularly shaped body in order to calculate its density. While taking a bath, he noticed that the level of the water in the tub rose as he got in, and realized that this effect could be used to determine the volume of the crown. For practical purposes water is incompressible, so the submerged crown would displace an amount of water equal to its own volume. By dividing the mass of the crown by the volume of water displaced, the density of the crown could be obtained. This density would be lower than that of gold if cheaper and less dense metals had been added. Archimedes then took to the streets naked, so excited by his discovery that he had forgotten to dress, crying "Eureka!" (Greek: "εὕρηκα!," meaning "I have found it!"). The test was conducted successfully, proving that silver had indeed been mixed in.

[analogfilter]

Planets as seen from Voyager 1.

[analogfilter]

This is a pic of my home brew dev board for AVR microcontrollers using a protoboard by adafruit. 

[analogfilter]

The Heliosphere

The heliosphere is often described as a kind of bubble that contains our solar system. This magnetic sphere, which extends beyond Pluto, is caused by the Sun’s solar winds. These winds spread out from the Sun at around 400 km/s until they hit what is known as interstellar space, which is also called local interstellar medium (LISM) or interstellar gas. Interstellar space is the space in galaxies that is unoccupied by either stars or planets.

When the solar winds hit local interstellar medium, a kind of bubble forms that prevents certain material from getting in. Thus, the heliosphere acts as a kind of shield that protects our solar system from cosmic rays, which are dangerous interstellar particles. The interaction between interstellar gas and solar winds depends on the pressure of the solar winds and properties of interstellar space, such as pressure, density, and qualities of the magnetic field. Astronomers believe that other solar systems have their own heliospheres caused by different stars.

There are several different parts of the heliosphere. The heliopause is the boundary between the heliosphere and the LISM. When solar winds approach this blurred region, they slow abruptly causing a shock wave to form known as the solar wind termination shock. The action is similar to slamming down on the brakes in a car, causing people and objects in the car to fly forward. This shock wave actually causes the particles to accelerate, aiding in the formation of the heliosphere. After it has slowed down, the winds of interstellar space act on the solar winds causing them to curve forming what has been described as a comet-like tail to the Sun. This tail, which has been examined by NASA’s probes Voyager 1 and Voyager2, is called the heliosheath. The termination shock is from around 75 to 90 astronomical units (AU) from our Sun, and at its closest point, the heliosheath is approximately 80 to 100 AU from the Sun.

[analogfilter]

This impressive demonstration shows that the simple harmonic motion of a tuning fork is really a sine wave in time. A laser beam is bounced off a mirror on the end of a tuning fork to a rotating mirror which provides the time axis. The tuning fork is driven by an interrupted magnet.