Anti-Matter vs. Dark Matter

The Collison Annihlation of Matter and Anti-matter

The Collison Annihlation of Matter and Anti-matter

What is the difference between anti-matter and dark matter? Is there anything anti-matter and dark matter have in common?

Anti-matter is the idea of negative matter, or matter with the same mass but opposite an charge and quantum spin than that of normal matter. Anti-matter is just like normal matter with different properties. The antimatter of the electron (e-)  is the positron (e+); similarly, the antimatter of the proton is the anti-proton (p-). When normal matter and anti-matter collide, the two annihilate each other. Scientists speculate that anti-matter and matter existed in equal quantities in the early Universe.  The apparent asymmetry of high quantities of matter and very low quantities of anti-matter is a great unsolved problem in physics. Anti-matter is only found through radioactive decay, lightning, and cosmic rays (high-energy particles from supernovae) and very expensive to produce. Practical uses of anti-matter include the positron emission tomography (PET) used for medical imaging and as triggers to nuclear weapons.

Dark matter cannot be seen and is hard to detect, because dark matter interacts by gravity and weak atomic force, not with strong atomic forces (nuclear force: holds subatomic particles, electrons, neutrons, and protons, together in an atom) or electromagnetism. Dark matter constitutes about 22.7% of the Universe. On April 3, 2013, the International Space Station’s Alpha Magnetic Spectrometer (AMS) found the first evidence of dark matter. [AMS was carried out by the Endeavor in 2011 in one of NASA’s last space shuttle flights.] Normally, detectors are blocked by Earth’s atmosphere, but by orbiting Earth above its atmosphere,  the AMS can monitor cosmos rays (have an excess of anti-matter, discovered two decades ago) without hindrance. The AMS will tell scientists whether the abundance of positrons signal the presence of dark matter.  One theory scientists are testing is supersymmetry, which speculates that the collision and annihilation of two dark matter particles could produce positrons. Another instrument that could help the dark matter hunt is the Large Underground Xenon Experiment (LUX).


Anderson, Natali. “Antimatter Hunter aboard International Space Station Detects Hints of Dark Matter.”, 4 Apr 2013. Web. 4 Apr 2013.

Boyle, Alan. “Space station’s antimatter detector finds its first evidence of dark matter.” NBC News, 3 Apr 2013. Web. 4 Apr 2013.


How It All Began: “To Infinity and Beyond”

Orion Nebula

From Nebulae to Stars to Galaxies and Beyond!


Mysteries galaxies cover,

Restlessness stars show,

Beauty planets exhibit,

In the infinity and beyond!

From minuscule neutrinos to the expanding Universe, astronomy rules the Fabric of the Cosmos. But in my birthplace, the sky is hidden by a mask of light pollution and fossil fuel wastes. I often pondered what lay above those hazy clouds. After emigrating from Shenyang, I saw for the first time a sky clearer than water and stars brighter than Zeus’ bolt. Thus began my fascination with astronomy. And like the constellations of the zodiac that appear in certain months, I had occasional close encounters with astronomy. There was a lesson in a 6th grade outdoor education class and a telescope viewing session in Pasadena. I even took an astronomy course at the community college. All of these transient, astronomical sparks ultimately culminated in my unforgettable COSMOS experience. My high school barely covers astronomy, so I rely on my home telescope, where all I can see is the moon, Jupiter, and Saturn. But in a university setting, I discovered and utilized the infinite, incredible resources for research and learning.

As the sun sank beneath the golden horizon, I waited patiently for the TAs to finish calibrating the 24-inch telescope inside the UCI observatory dome. After Dr. Smecker-Hane explained how to use a sky map, I mastered the technique and shouted out constellations: “Orion! Big Dipper!” Inside the observatory dome, I ascended the creaky steel ladder and gazed into the telescope’s eyepiece, seeing one area concentrated with stars, the open cluster M11. Though light years away, M11 seemed so impossibly close that I could reach up and snatch its stars out of the sky, as though I was a scientist observing stars on an ebony Petri dish through a microscope. On the 8-inch telescope, Mars shone like ancient blood-stained battlefields, while Saturn’s ice rings revolved as magnificently as clockwork.

The professors enlightened me with intriguing astronomy stories, such as the irony of Einstein’s obstinacy. Though he rejected Friedmann’s theory of an expanding universe, Einstein’s cosmological constant, when reversed, actually supports the theory of Universe acceleration. The program’s CLEA1 exercises prepared me for group projects as I learned some of the math behind astronomy― calculating the mass of Jupiter using its moons’ orbits and “blinking” to determine asteroids’ velocities. In one CLEA simulation, I found not galaxies, but portraits of scientists floating in space instead! For my group research project, “Stellar Spectra,” we observed the night sky, recorded images of Arcturus and Vega, reduced them with Linux software, and designed a poster board decorated with colored dots depicting the stars of the H-R Diagram. We presented our “findings” to parents, students, and professors at a science fair convention. During this research process, I imagined myself as the modern Galileo voyaging through territory few had traversed.

COSMOS was the launch pad in expanding my astronomy blog, coincidentally named “The Cosmos.”I blog actively, and have discovered kindred spirits with minds eager to learn, inquire, and comment. Originating globally across six continents in countries like Germany and India, the feedback I receive increases my fascination. COSMOS confirmed my desire to study astronomy, conduct research, and become a part of the scientific community. Astronomy is the oldest science, yet each discovery raises more questions. In every astronomical encounter I travel on an unforgettable journey invoked by imagination.

1 CLEA is an acronym for Contemporary Lab Experiences in Astronomy.

~ Tianjia Liu, 2012 ~

Supernovae: Dying Stars

Star Death

Lifetime of a Star

It is true that all living things come from stardust. In about 5 billion years, our Sun will have swelled to a red giant and engulfed the inner planets, ready to explode in a supernova. Supernovae enrich the interstellar medium with high mass elements, like iron and calcium. The high energy from supernovae also triggers formation of new stars. On average, supernovae occur only about once every 50 years in the Milky Way Galaxy. They are rare events— so rare that the last one in the Milky Way was discovered in 1604 (SN 1604, or Kepler’s Supernova)— spectacularly luminous and extremely destructive. In fact, supernovae can cause bursts of radiation more luminous than entire galaxies and emit as much energy as the Sun will in its entire lifespan! In a supernova, most of the star’s material is expelled into space at speeds up to 30,000 m/s. The shock wave passes through the supernova remnant, a huge expanding shell of gas and dust. Supernova are caused either by the sudden gravitational collapse of a supergiant star (Type I Supernova) or a white dwarf accreting enough mass or merging with a binary companion to undergo nuclear fusion (Type II Supernova). White dwarfs are very dense stars that do not have enough mass to become a neutron star (formed from supernova remnant, stars comprising almost entirely of neutrons). Supernovae can be used as standard candles (objects with known luminosity). For instance, the dimming luminosity of distant supernovae supports the theory that the expansion of the universe is accelerating. Now, with powerful telescopes like Hubble, many supernovae are discovered each year. How perfectly supernovae represent the circle of life: from death comes life!

History of Supernova Observations (Milky Way)

  • SN185 by Chinese astronomers
  • SN1006 by Chinese and Islamic astronomers
  • SN1054 (caused Crab Nebula)
  • SN1572 by Tycho Brahe in Cassiopeia
  • SN1604 by Johannes Kepler

* Supernova (SN) are named by the year they are discovered; if more than one in one year, the name is followed by a capital letter (A, B, C, etc.), and if more than 26, lowercase paired letters (aa, ab, etc.) are used

Below is a video on supernovae! Enjoy.

Fun Facts Cluster 2: From Space Rocks to Drones (AskAstro)

1. SPACE ROCK SUICIDE: Scientists can detect a comet or asteroid colliding into the Sun’s surface. The self-destructing comet or asteroid will explode due to pressure of traveling into the Sun’s photosphere. The brightness and impact of the collision depends on the mass of the object. A collision as such is high unlikely, however, because: 1) most comets and asteroids would to dust and vapor in the sizzling atmosphere of the Sun 2) objects will lose most of its mass as they approach the Sun 3) objects normally orbit the Sun, so the objects’ orbit must be altered or the object may be from another planetary system.

2. STELLAR DONATIONS: In a binary star system, if stars are close enough, tides can become so strong that the more gravitationally strong star call pull gas from the surface of its companion. Though the “tidal transfer” depends on the mass of the donor star, if two stars have equal mass, the accretor (the star gaining mass) will steal mass if the donor star’s radius exceeds 38 percent of the binary separation (distance between the stars) no matter the separation.

3. COLOR CODE: The dark and light horizontal bands depend on the organization of winds in Jupiter’s atmosphere. The light bands have a eastward jet on the side closest to the pole, and vice versa in the dark bands. The zones (light bands) appear bright because of colorless high-altitude clouds that contain ammonia ice. The belts (dark bands) have much thinner high altitude clouds and darker particles.

4. DANGEROUS FLYBY: NASA calculates the planetary flybys with nothing but Newton’s laws of motion. The desired closest approach depends on the mission and how much added velocity boost the mission requires.  The mass and closeness of the planet determines the bending of trajectory the probe must undergo. The approach distance can range from a few hundred to several thousand kilometers.

From: Astronomy magazine December 2012 Vol 41 Issue 12

The “Zombie” Planet Rises

The Zombie Planet

World War Z? Certainly looks like it. A planet though to be buried has come back alive… undead, some might say. Coincidentally, the analysis of Hubble Space Telescope’s observations came  right before Halloween. The massive alien zombie planet, called the Fomalhaut b (the name even sounds creepy, if you ask me), orbits the star Fomalhaut, which is 25 light years from the constellation Piscis Austrinus. These recent discoveries, however, contradict conclusions in November 2008 that indicated Fomalhaut b as a giant dust cloud. Fomalhaut b, three times smaller than Jupiter, was the first planet directly imaged in visible light. The planet seems to be inside a vast debris ring. Because the scientists did not discover any brightness variations in the 2004 and 2006 Hubble observations, they concluded that Fomalhaut b must be a massive planet. Watch the Halloween-themed video below on the Zombie Planet!

References “Massive ‘zombie’ alien planet rises from the dead.”, 28 2012. Web. 28 Oct 2012.

Temperature of the Universe

What is the universe’s temperature? How has it changed and evolved? What causes the temperature to change? How is the temperature estimated? Is it continuously cooling or constant? –Pcelsus

Black Body Curve of the Cosmic Microwave Background

13.75 billion years ago, the Universe was much smaller and hotter. In the 1960s, Robert Dicke predicted a remnant “glow” from the Big Bang. In 1965 at the Bell Labs, radio astronomers Amo Penzias and Robert Wilson discovered that glow, named the cosmic microwave background radiation. The CBR was seen in all directions in empty space, with a black body curve (temperature ~3K in every direction). About 1 second after the Big Bang, the Universe was very hot, at ~1 billion K. At 3 minutes, protons and neutrons combine to form the nuclei of atoms. As space cooled, material condensed and atomic particles, then elements, molecules, stars, and galaxies formed. The hydrogen/ helium ratio (3:1) found today is about the same as what’s expected after the Big Bang. Atoms were “ionized” with electrons roaming free without being bound. At 300,000 years after the Big Bang, the Universe becomes transparent with a temperature of 3,000K. Light red-shifted by a factor of 1000, and the expansion of the Universe ensued.

Today, the Universe is 2.73K, or 2.73°C above absolute zero, but at the beginning of space and time, the Big Bang, the Universe reached over one billion degrees. From a single pinpoint, the Universe emerged as a scorching hot primordial soup of subatomic particles moving at high velocities. As the Universe expanded, the temperature cooled as more space was created and density decreased. The Universe is continuously cooling as it expands.

Measuring the temperature isn’t as simple as sticking a thermometer in space and waiting until it stabilizes at a certain temperature. Instead, scientists measure indirectly using the cosmic microwave background, or leftover radiation emitted by hot plasma 38,000 years after the Big Bang. As the Universe expanded, the electromagnetic waves of the CMR elongated and decreased in energy, leading to cooler temperatures. Using Planck’s law, scientists measured the black body radiation of the Universe. Planck’s law states that every object radiates electromagnetic energy according to temperature. Black body curves are lopsided, with the curve peaking at different wavelengths depending on the object. In fact, space has a nearly perfect black body curve, since physical objects tend to absorb and reflect light in certain wavelengths.