Galactic Geometry

Symmetries of all sorts fascinate me. I often contemplate small scale and large scale symmetries, from isospin symmetry of the nucleon, to the eight-fold way in particle physics, to snowflakes, to geometric transformations, to galactic geometry.

Being this is technically suppose to be an astronomy and astrophysics blog, I decided to post about one of the most obvious symmetries of modern cosmology, which lucky for us, occurs in our own galaxy, the Milky Way Galaxy as we know it.

"The plane of the Milky Way galaxy is tilted at almost exactly 60 degrees to the ecliptic of plane of our solar system. What is more, every year the Sun crosses the galaxy through the galactic center, and being alive in these times means this happens on midwinter's day." (Martineau, John, "A Little Book of Coincidence" 2002.)

Antimatter

To understand antimatter, Let's quickly revist my previous post where I defined what an antiparticle was. For those of you just joining, I'll quickly outline it again and also add some useful information.

An antiparticle is similar to a particle in that it has the same mass and spin. The difference is opposite charge.
The famous example, the antiparticle of the electron is the antielectron, better known as the positron.

When particles and antiparticles collide, they annihilate, however, they don't just simply vanish. Instead, due to conservation of energy and momentum, they annihilate to create different particles. In the case of the electron and positron, they annihilate to produce two identical gamma ray photons both with an energy of .511 Mev/c^2 speeding off in opposite directions. Which is precisely the mass/energy of the electron/positron. Of course, the lifetime of the gamma ray photons are short lived. The lifetime of the positron is also short lived. This is due to 1) matter dominating the universe and 2) since all things are made of matter, it isn't very difficult or very long before a positron collides with an electron.



Above, is an image I found online outlining fundamental particles and their antiparticles. Of course they skip the gauge bosons. But I can outline them quickly and in a simple way.

Photon: due to its charge, it is its own antiparticle. "A photon is a photon is a photon" famous words of someones... but referenced from whom I heard it said, Professor Claire.

Z: Is also its own antiparticle.

W+: Its antiparticle is the W- boson.

W-: Its antiparticle is the W+ boson.

Gluon: the gluons are the more complicated guys. As it turns out, all gluons carry color flavors or rather, color charge. There are three types of color charges, red, blue and green. Therefore, there are three anticolor charges, anti-red, anti-blue and anti-red. Color charge of gluons involves a more in depth explanation and understanding. The following link, explains it very well and way better than I can.. Theory: Color Charge

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Note: I just wanted to point out an important thought regarding anti-hadron configurations. We know that the proton (which is a hadron and Baryon) is made up of two up quarks and one down quark. The correct way to think about an antiproton would be as follows: two anti-up quarks and one anti-down quark.

(the WRONG way would be to say two down quarks and one up quark. That would actually be a neutron!)

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Now that we know what antiparticles are, Let's talk about antimatter! For starters, did you know that certain radioisotopes are natural positron emitters (specifically, Beta-plus decay)? This means that these radioisotopes are emitting anitparticles during their decays. Interesting enough, recall what I mentioned above regarding the fact that we have only known about antiparticles for approximately 85 years? Well, this indicates that even though the periodic table was practically fully developed and radioactive materials had already been discovered, we had no idea that radioactive decays involved antiparticles.

With that being said and tons of new particles being discovered, it is no wonder why particle physics boomed. I read somewhere, that "The next people to discover a new particle should be fined rather than given award money."

Efforts are currently being made to analyze the properties of antimatter, more specifically antihydrogen (An antiproton and a positron), and to trap/contain it. Current projects such as ATHENA, ALPHA and ATRAP at CERN have pioneered cold antihydrogen, accurate hydrogen spectroscopy, first observed hot antihydrogen atoms and own the record for trapping anti-hydrogen for the longest amount of time, less than 16 minutes the last time I checked, which was just last year. (I may do an additional post on traps and how antiparticles are contained if I have time or if someone would really like to hear about it.)

I sometimes allow myself to envision a periodic table of antielements. A professor of mine told me that was silly. However, the funny thing is, I'm not the first and definitely will not be the last. Charles Janet had this vision long before I did, circa 1929. Before the positron was even observed.

Before I conclude this post, I would like to propose some questions for everyone to think about and perhaps discuss or comment on. :)

1) Why the apparent asymmetry of matter and antimatter in the visible universe?! (Look up Baryogenesis)

2) "Antimatter may exist in relatively large amounts in far-away galaxies due to cosmic inflation in the primordial time of the universe. If antimatter galaxies exist, they are expected to have the same chemistry and absorption/emission spectra as normal-matter galaxies, and their astronomical objects would be observationally identical, making them difficult to distinguish."

How then can we confirm whether or not they do or don't exist?!

3) What are the main techniques in trapping antimatter and more importantly, how can they be improved?!

4) Does antimatter fall up or down via the force of gravity?!

(I had so many questions but now cannot remember them all. Don't worry, when they come to me, I will update this post. Perhaps 5 is more than enough!)

The Standard Model of Particle Physics

Lately, I have been wanting to blog about antimatter. However, before I jump right into the middle of things, let's start from the beginning, shall we? For those of you that have already had the pleasure and/or pain of experiencing my particle rants, bear with me. :) For those of you who have yet to experience my enthusiasm, let's go!!! :)

The majority of us know what matter is, after all, it makes up everything around us. We are even physically made up of it. Protons, neutrons, electrons ... we know of these "particles" that we are made of... we've heard of the periodic table in Chemistry. Looking a bit closer (well not literally right?! I mean can we actually see an electron? Or better yet, has anyone ever observed an electron... go on... think about it?!), we have found that some particles, such as the proton and neutron are in fact made up of smaller particles. Trying to understand how many particles there are, how to classify them, or which are the fundamental particles (i.e. which are the smallest building blocks of matter) can get chaotic very quickly. So let's take a look at the classic image below.



As you can see from the picture, there are three generations of matter. Basically what that means is that the first column existed first, then column 2 came into existence and lastly column three.

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Starting with the Leptons, we see that there are three generations and along with each generation, a neutrino. Leptons are easy to understand. We know of the first generation of Leptons, right? Electrons?! So let's add a little side kick to our electron friend and name it the electron neutrino. Next we have the Muon and its side kick, the Muon neutrino, it's a lepton just as the electron only it is greater in mass and/or energy. Lastly, we have the Tau and its side kick, the Tau neutrino, it's a lepton just as the electron and muon only it is greater in mass and/or energy than both the first and second generations. That wasn't so bad, right?! :)

Moving on to the quarks, we can easily see how fun these guys are. I mean, just read their names... up, down, charm, strange, top and bottom. Originally top and bottom were named truth and beauty, but those names didn't stick. We call these the six quark flavors. (Doesn't flavors make you feel like you're in an ice cream parlor... trying to decide on which one you really want on your cone. Luckily with quark flavors, there are only six! You know what that means? If you were in a quark parlor, you could easily have all six... well not quite. You'll understand why soon enough!)
Quarks evolved in three generations along with the leptons. As it turns out, quarks are the particles that make up the particles we are more familiar with, such as the proton and neutron.

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Now before I get to the Gauge Bosons.... I need to explain a couple of important things.

1) Antiparticles : An antiparticle is the same as a particle except it has opposite charge.
For example: The antiparticle of the electron is the positron. It has the same mass and spin, but has a positive charge instead of negative charge. (There are some particles, that are in fact their own antiparticle. This comes about typically for particles with zero charge. For example, the photon. This we will see when we discuss Bosons.)

2) The are three classifications of particles, excluding Bosons. These three categories are the Leptons, Mesons and Hadrons. The easiest way to think of these categories is as follows:

Leptons: Little particles - Electrons, Muons and Taus (and of course their side kicks.)

Mesons: Medium particles - these are quark-antiquark pairs. - Ex: up quark anti-up quark, etc.

Hadrons: Heavy particles - these are particles that are made up of 3 quarks. - Ex: the Proton, which is made up of two up quarks and one down quark.

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Now for the Gauge Bosons:

There are technically six gauge bosons and Bosons are the force carriers.

Photon: Electromagnetic force carrier.

Gluon: The strong force carrier.

Z: A weak force carrier.

W+ and W-: Weak force carriers.

Higgs: According to wikipedia, "the Standard Model's explanation of why some fundamental particles have mass when 'naive' theory says they should be massless, and - linked to this - why the weak force has a much shorter range than the electromagnetic force."

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One thing that I will add, which perhaps you're wondering or will eventually be wondering, is how are the quarks bound together?! The simplest answer is via the gluons. In reality, it's more complicated than my simple answer. However, think of it like this, the gluons are the glue that hold the quarks together. :)

So there you have it, The Standard Model of Particle Physics.


Below, I have included a link of a website sponsored by the Particle Data Group and NSF. This site offers information regarding particles, accelerators, mysteries in physics and then some. It's an awesome site, do take a peek.

The Particle Adventure

Diffraction Limits of Telescopes and Blackholes

Question number 4 from last week's homework (WS 4), really had me thinking. For starters, who doesn't find blackholes interesting?! Don't you?! I ended up realizing, as I'm sure the rest of you did, that building a telescope to resolve the event horizons is a difficult task. Then getting the telescope to be able to resolve both event horizons is another task.

I ended up writing a simulation in Mathematica to demonstrate how large of a diameter the mirror of the telescope would have to be to resolve both event horizons at the same wavelength.

In order to view and mess with the simulation, you will need to download the Wolfram CDF player. You can download it here!

Here is a little preview...

Enjoy!

"The Universe is a Place of Great Variety - After All, it has Everything in It!"

Galileo Galilei: A "modern" astronomer - Photo Courtesy of wikipedia.

Throughout history, the studies and observations of the universe have led to discoveries that have effected humanity and the way we think. Astronomers were the ones to make these discoveries, such as Copernicus, Brahe, Kepler, Galileo and Newton.

Modern Astronomy is a dense field and interesting enough it's origin was in the 17th century. This means that Kepler, Galileo, Newton and Halley are all considered "modern" astronomers. (Hundreds of years later, astronomers are still considered "modern"?) 21st Century astronomers (i.e. today's astronomers) do it all, from mapping our universe to describing behavior of celestial objects with physics. They are not just observers. They have in my opinion, one of the hardest objectives out of many fields, to construct models of objects and/or complex systems of objects that are light years away. This is an extremely difficult task, not just because objects are so far away, but due to the amount of time it takes to accomplish it. Astronomers are dealing with objects that have lifetimes beyond our comprehension. They will never have the ability to trap a star and bring it into the lab for experimentation, let alone a solar system or galaxy. 21st century astronomers also work on things like space travel, rockets, telescopes, detectors, and how to prevent the earth from being hit by a celestial object, perhaps a meteor or comet. Astronomers are remarkable, and like many scientists, are dedicated (dare I say patient?) individuals.

Another job of the modern astronomer is to give humanity a sense of scale of the universe. This incorporates the scale of our everyday experience and then expands in either direction of the very small and very large. This sense of scale includes many things, such as distance, size and time. On that note, check back soon for a post on just that, a sense of scale.


References:

Pasachoff, Jay A., Astronomy: From the Earth to the Universe. 1991. Saunders College Publishing, a division of Holt, Rinehart and Winston, Inc.

A Yotta Stars!

Ever look up into the sky and wonder how many stars there are?

For some, "a lot" is not a very satisfying answer.

Although, we will never really know how many stars there are in the universe, here is a simple calculation that will give us a "rough estimate":

A little background info first...

Galaxies range from Dwarf to Giant. Dwarf galaxies have between ten million (10^7) stars to several billion. While Giant galaxies have a hundred trillion (10^14) stars. It is also said, that "there are probably more than 170 billion (1.7 x10^11) galaxies in the observable universe".

So taking the average of (10^7) and (10^14) we get (5 x10^13)

Then if we take the average of (5 x10^13) and multiply by (1.7 x10^11)

we get approximately (8.5 x10^24) stars in the universe.

That's 8.5 yottas! Or a Septillion (If you're American or French) Or a Quadrillion (If you're English or British).

Any which way, that's a "yotta" stars.


(This of course is just a rough approximation.)

1. "Unveiling the Secret of a Virgo Dwarf Galaxy". ESO. 2000-05-03. Retrieved 2007-01-03.
2. Uson, J. M.; Boughn, S. P.; Kuhn, J. R. (1990). "The central galaxy in Abell 2029 – An old supergiant". Science 250 (4980): 539–540. Bibcode1990Sci...250..539U. doi:10.1126/science.250.4980.539
3. Gott III, J. R.; et al. (2005). "A Map of the Universe". Astrophysical Journal 624(2): 463–484. arXiv:astro-ph/0310571. Bibcode 2005ApJ...624..463G.doi:10.1086/428890

The Great Unknown

As a child, living in the mountains wasn't very cool.  I couldn't ride my bike to my friend's house or to the local ice cream parlor and I surely didn't live in a cul-de-sac.  My days out of school were spent exploring, pretending large rocks were rocket ships and riding my bike down dangerous rock roads.   My nights however, were spent starring up into the night sky.


Like so many of you, as I starred up into the night sky, I was lost in thought.  So many questions and yet very little answers.  I knew of the milky way, the planets, stars, etc.  But little did I know.


Time flew by, and to tell you the truth, my love for astronomy was merely a hobby.  My true desire as a child was to become an inventor.  I was really good at rigging up "inventions" with all of my parents stuff.  This only made them furious, as I was ruining and wasting their good "stuff".  At the time,  I really felt they just lacked imagination.  


Before I knew it, I was all grown up.  Many things changed, but there was one thing that never did.  I never stopped spending those hours in the early morning starring up into the Great Unknown.  So what did I do next, you ask?


I saved up some money and purchased this baby:

A Celestron 14 inch Dobsonian telescope.


I became a true amateur astronomer.  My favorite things to view were saturn, the orion nebula, and the moon.  (Did you know that you should view the moon last while using a telescope? Leave a comment and tell me why! :p)


These days, I try my best to view all of the meteor showers I can and estimate how many meteors I see per hour.  Of course if my studies allow it.


My interests in physics began by looking up into the night sky, into the great unknown and asking many many questions.  I'm still asking questions...


Below are a few articles I wrote regarding meteor showers:


Leonid Meteor Shower Local Watching Locations


Review of the 2010 Leonid Meteor Shower in Southern California

2010 Geminid Meteor Shower