21 cm cosmology

I haven't blogged in a very long time! I've been spending most of my intellectual energy and free time trying to learn spanish and graduate college instead of nerding out. However, for the next two months I plan on: 1.) Being really broke and 2.) Having lots of free time. This means many more blogs are on the way! Suggestions are welcome. In the meantime, I'd like to share a paper I wrote for my cosmology class this quarter.  It used to be full of lots of equations to describe the quantum behavior of hydrogen but I can't figure out how to insert equations in this thing. Does anyone know how to do that?

 It's a little different than the way I usually write in this blog but maybe you'll dig it anyway!

21 Centimeter Astronomy

The Dark Age

Applications of quantum mechanics have proven to be of great utility in the expanding field of radio cosmology. As astronomers begin to piece together answers to the question, “what did the early universe look like?”, the quantum model of hydrogen plays a large role. Understanding the nature of hydrogen’s hyperfine structure and it’s interaction with radiation becomes crucial to this investigation.

Hydrogen has a forking energy structure: each branch separates into a different set of branches. This branching begins with electrons, which exist in quantized energy levels, known as orbitals, around hydrogen nuclei. Within these orbitals the electrons are subject to two types of angular momentum: orbital (associated with motion of the center of mass) and spin (associated with motion about the center of mass).  While it should be noted that electrons are fundamental particles without interior structure, (and therefore cannot literally spin) this analogy is useful in analyzing the splitting behavior of orbiting electrons. Suffice it to say that electrons carry an intrinsic angular momentum which can alter the total energy.  It is spin that creates the hyperfine structure of hydrogen.

According to classical electrodynamics, a rotating electric charge creates a magnetic dipole. This sets up the electron as a magnetic dipole. The proton, like the electron, has an intrinsic spin, which sets up its own dipole moment in the same direction as the proton’s spin. The dipole of the proton is more complex because it is a composite structure, made up of three quarks, which gives a different gyromagnetic ratio. The proton’s dipole moment creates a magnetic field.

            The difference between levels in hydrogen’s hyperfine structure is an artifact of the interaction between the electron’s dipole moment and the proton’s magnetic field. If the dipole moments of the electron and proton point in the same direction (parallel) the energy of this configuration is slightly higher than if the dipoles point in the opposite direction (antiparallel). It is found that the frequency of a photon emitted during the transition from parallel to antiparallel is 1420MHz, which corresponds to a wavelength of c/v=21 cm. This falls within the microwave region of the electromagnetic spectrum.

The probability of this transition taking place is so small that it is classified as forbidden. To be precise, the probability of such an event taking place is 2.9*10^-15 1/s, or once every 10 million years. As a result, it can never be manufactured in a laboratory. However, evidence of this transmission is detected pervasively in all directions as astronomers look into space. Carl Sagan and Frank Drake considered the 21cm line to be so ubiquitous and universal that they utilized it on the Pioneer Plaque of the Voyager Mission as a single unit measurement in defining length and time. The omnipresence of this extremely improbable detection indicates that the universe contains a tremendous amount of neutral hydrogen.

The dumbbell looking thing the the upper left hand corner represents hydrogen undergoing a spin-flip transition. For those of you that don't know about this plaque, it's floating out in space with the hopes that someday aliens will find it. This plaque and the rest of the bizarro messages on board the Voyager definitely deserves it's own blog. Hopefully I'll get to that soon!

Of special importance to big bang cosmologists are the 21cm transmissions detected at redshifts between z=25 and z=10^3. Radiation detected in this range comes from a period between two important epochs of gas phase change in the early universe: recombination and reionization. To give a brief history of the state of hydrogen throughout time, shortly after the big bang, the universe was radiation dominated. During this period, protons and electrons could not combine to form neutral atoms without being quickly ionized by energetic photons. However, the universe cooled as it expanded, eventually allowing for this reaction to take place. This is known as the epoch of recombination and took place around redshift z=1100.  For several hundred million years following recombination there were no radiating sources, only cold, dark hydrogen. For this reason, the period is referred to as the Dark Age. In this epoch the universe was transparent, meaning photons could travel unimpeded through space. This is important to cosmologists as it means there is much information retained in the photons. The second epoch of the universe, known as reionization, occurred after the gravitational interaction between neutral hydrogen atoms allowed for the formation of the first structures large enough to radiate and ionize surrounding atoms. Astronomers interested in probing the structure of the universe between these two phase changes, when the universe was dominated by cold, dark hydrogen, must examine the fingerprints of such an era:  21cm photons.

Photon emission due to the spin-flip transition of hydrogen is temperature dependent. This means as 21 cm photons are released they will catalyze other reactions from neutral hydrogen nearby. By mapping the intensity of this radiation, cosmologists can develop a precise picture of the topography of the universe during the Dark Age. This is predicted to provide crucial constraints on current models for dark matter and dark energy. Furthermore, neutral hydrogen that has been ionized by those first radiating structures will appear as dark spots in the 21cm background. By examining these anisotropies, cosmologists can gain a firmer understanding of how the process of universal reionization occurred.

Research involving the 21cm line places cosmology on the verge of a new era. However, this field has a long way to go as observation of this transmission is extremely difficult. After redshift, this line is observed on Earth deep into the radio spectrum. This presents many challenges in collecting data as photons in the 21cm spectrum are drowned out by background noise from television transmission and the ionosphere. In the last few years, progression has been made both theoretically and observationally: theoretically, computer simulations of reionization have achieved larger dynamic range and can make more reliable predictions; observationally, plans have been made for four machines to start sensitive 21cm detection in the near future. Precise observations of the 21cm line from distant redshifts promise to revolutionize our understanding of the early universe.   

Sources

Griffiths, David. Quantum Mechanics. 2nd. Upper Saddle River: Pearson Education, 2005. Print.

Pritchard, Jonathan, and Loeb Abraham. "Evolution of the 21 cm Signal Throughout Cosmic History."

Miguel, Morales, and Wyithe Stuart. "Reionization and Cosmology with 21-cm Fluctuations." Annual Rev. Astron. Astrophys.. (2010)

Perception, LSD, and Synesthesia

PERCEPTION. It's crazy, right? The way you view the world around you depends so much on your current state of mind. Whether your perception is altered by your mood, illness, or drugs, it’s plasticity is almost frightening.

Of course, one of the easiest and most marked alterations you can make to your perception is via hallucinogenic drugs. I’ve never tried them myself just because the thought of letting my imagination become my reality kind of terrifies me, to be honest. I don’t think I am emotionally mature enough to deal with the monsters that my personal psyche would create for me. Not yet, anyway. At some point in my future, however, I would love to hallucinate. I think it would be a fascinating experience. I’ve heard that some people are forever changed after taking LSD. You can talk to God. You can come to life-shattering realizations about the universe. Your spirituality and worldview might be forever altered. Like this guy. On the darker side, however, some people come out of LSD trips with permanent psychosis.

It’s hard to find accurate accounts of what people actually experience while on LSD. Google will bring up government websites with obvious bias toward scaring people away from drugs or hippy forums that seem pretty sketchy and not very reputable. Since the experiences of those who take acid are so personal and individualized, I think the best resources available to me are personal anecdotes.

I spent a little time watching people take LSD and talk about their trips on YouTube. Apparently to some people it sounds like a good idea to take video of them selves doing illegal things and post it on the internet. It’s amazing how many people will willfully and enthusiastically incriminate them selves. I did find some interesting stories though. This one is good.

He brings up the monumental question, “what is reality?”. Questioning what is real seems to be common among LSD users. Some people, like the hippy I linked above, might challenge the idea of reality for the rest of their lives. You can see, hear, smell, taste and feel “unreal” things while you are on acid. To the tripper, these things are completely tangible. How could that not eff with your perception of reality?

It’s difficult for our minds to grasp the fact that all sensory perceptions are just electrical and chemical signals in our brains. The reason my computer screen looks the way it does is because photons of a certain frequency stimulate my retina and cause it to send signals to my brain. The same goes for all the information that my brain is taking in from my surrounding: sounds, smells, temperature, air pressure, everything. My brain uses electrical and chemical processes to somehow construct my understanding of what is around me. This understanding of my surroundings is projected into my consciousness and it is the only way I can relate to reality. If the mechanism that allows us to interact with reality is altered, then our personal reality is altered. This can be a significant, permanent change.

If people are forever changed by taking LSD, then it must be permanently altering the structure or function of the brain somehow. But how?

Well… I guess first of all I need to figure out what LSD is, exactly.

LSD stands for lysergic acid diethylamide. So it’s made from reacting two chemicals: lysergic acid and diethylamide.

What are those two things?

Looks like lysergic acid is the good part…

Lysergic acid is found in a fungus known as ergot, it commonly infects rye. More specifically, ergot has high concentrations of a chemical called ergoline. It is from ergoline that lysergic acid is extracted.

When ergoline is ingested it does some knarly things to the body including constricting blood vessels, causing convulsions, headaches, nausea, vomiting, and most famously: hallucinations.

People have known about ergot for a long time. Since the middle ages, controlled doses were used by midwives to induce abortions. There is also evidence of its (intentional?) use thousands of years before this as ergot was found in the stomachs of prehistoric human remains preserved in bogs. Perhaps it was used in prehistoric rituals of spirituality.

It has also been ingested accidently on several famous occasions. Turns out ergot is a trifling little fungus that may have had a hand in several historical events. Many historians have suggested that the behavior of the young women who were “bewitched” during the Salem witch trials was due to ergot poisoning. It has even been linked to The Great Fear, wide spread panic among peasants that helped spur on the French Revolution.

As for the D part of LSD, diethylamide, it’s a bunch of carbons, hydrogens, and a nitrogen strung together. You can get it from mixing ethanol and ammonia. I’m not quite sure of its purpose in LSD. It might be a potentiator, a chemical that enhances the hallucinogenic effects of the lysergic acid. With a potentiator like this, you can just take a drop and go on a mental vacation without the unpleasant effects from the ergoline like vomiting, diarreah, gangrene, ect…Diethylamine sounds like a plus.

OK, so what is it doing to your brain?

Well, LSD is structurally very similar to a chemical called serotonin. 

Serotonin is a neurotransmitter, a chemical that transmits signals from neurons.

This is how neurotransmitters work:

Neurons have lots of little packets of chemicals inside them (like serotonin). When a neuron receives an electrical impulse from the nervous system it converts this electrical signal into a chemical signal by releasing the little packets of neurotransmitters.

Here is a really cool animation.

This one is not as cool but it explains what is happening.

The neurotransmitters swim around in your brain and bond with receiver cells and this causes many varied responses in your body. In the case of serotonin, it might affect your mood, anxiety levels, appetite…the list goes on and on.

I didn’t know much about serotonin so I did a few google searches and I found this great blog by neuroscientist Sheril Kesenbaum that gives a fantastic run down on serotonin. 

Man, I tried really hard to understand what serotonin was all about. One thing Dr. Kesenbaum said that made me feel much better is that no one really understands serotonin because the serotonin system is insanely complicated. Serotonin has LOTS of different functions in our bodies and it fulfils these functions in many different ways.  

When the LSD molecule enters our brain, since it looks a lot like serotonin, it binds to serotonin receptors. This is where LSD gets unpredictable: sometimes it will excite the receptor and sometimes it will inhibit it. The effect is a flood of serotonin or no serotonin at all. This is happening at several serotonin receptors throughout the brain.  When a person takes LSD they are messing with their natural ecosystem of serotonin on a grand scale. For reasons no one understands entirely, this causes a marked change in your sensory perceptions.

LSD distorts sensory perceptions in several ways. My favorite is called synesthesia. This is where sensory perceptions tend to blend together. IE: A person may see music or hear/feel color. This word comes from a real medical condition. Ok, after reading up on it a little, synesthesia is actually my new favorite thing. Synesthesia is a real, documented psychological condition in which the stimulation of one sensory pathway leads to the immediate stimulation of another, unrelated pathway. So, for some people the sound of middle C on a piano might smell like roses or maybe every time they see a humming bird they will taste chocolate or if they have a toothache it will have a color, smell, and taste.

The most common manifestation of synesthesia is that letters and numbers will have a certain intrinsic color. IE: G is orange. 8 is purple. They just are. And yes, they are actually SEEING these colors along with the numbers or letters, not just imagining them. The most compelling evidence is that brain scans reveal the visual color processing sections of a synesthete’s brain lighting up when they are shown a certain number or letter. Furthermore, the colors they report seeing are consistent. If they see J as pink at age 9 it will still be pink when they are 32, and the same goes for all other letters and numbers that have a color. If this were just an artifact of imagination it’s hard to imagine that such remarkable consistency would be maintained throughout a person’s lifetime.

Since you don’t question what you are experiencing until you realize that everyone else is not experiencing the same thing, many people don’t even realize that they have this condition. I found this book on synesthesia called The Frog Croaked Blue and there is this cool quote from a woman who describes the moment when she realized that she perceives the world differently than everyone else,

 “I did not 'discover' my synesthesia until I made a comment to my parents in my mid-twenties about a number. They were disputing some number that I had given them as a statistic and I said, by way of proof, that it could not have been seventy and had to be forty because it was a red number with a warm feel, and it was only halfway up the line to 100. It is extremely strange when the two people who know you better than anyone else regard you as though you were a complete alien. I then went on to describe how my numbers are not only colored, but also have very distinct patterns, as does time - the time of day, days of the week, months within the year, and the years themselves.”

Most synethetes view this as a gift that helps them excel at certain tasks such as spelling, arithmetic, memorization, composing... the list goes on. Two famous composers, Franz Liszt and Nikolai Rimsky Korsakov once had a public disagreement about what color certain keys were! I have no idea of the circumstances of the argument but I really like to imagine these two heartily debating the color of a sound in a room full of uncomfortable people who have no idea what they are talking about because to everyone else, sounds are not colors.

Many brilliant people have been known to be synethetes. As a child, Vladimir Nabokov insisted that the colors of the letters on his blocks were all wrong.  Physicist Richard Feynman describes his colored equations,

"When I see equations, I see the letters in colors – I don't know why. As I'm talking, I see vague pictures of Bessel functions from Jahnke and Emde's book, with light-tan j's, slightly violet-bluish n's, and dark brown x's flying around. And I wonder what the hell it must look like to the students."

One of the things I find the most interesting about synesthesia is that certain perceptions seem to be consistent among different synesthetes. For example, for those who have color/letter synesthesia: S will tend to be yellow, A tends to be red, O tends to be white or black. Different people tend to agree on the intrinsic color of certain letters!

Ok, come with me into the weeds for a sec…

If one person can observe something that is completely tangible to them, it doesn’t necessarily constitute reality. BUT if several people see the same thing isn’t THAT reality? I mean…if you see something unbelievable the first thing you will probably do is ask someone else, “Do you see that too?” and if they do then you know it’s real and not just in your head. If more than one person can agree on seeing the same thing then …What IS this? Is this a different reality?

Synesthetes’ brains must be different from the brains of regular/boring people like me some how. But how? It seems that no one is really sure.

If LSD is temporarily inducing these effects in people who don’t have synesthesia and LSD is known to affect the serotonin system…perhaps it has something to do with serotonin?

Do you have synesthesia? I would love to talk to you about the awesome way you see the world around you!


Obviously, much more research should be done on perception, LSD, and synesthesia, but alas, this subject seems to have widely been abandoned by psychologists and neuroscientists. Perhaps it's a reputation ruiner these days. I did find this 2010 project from the Multidisciplinary Association For Psychadelic Study, though. They used a mysticism scale to quantify spiritual experiences! Imagine that. The mysticism scale was developed by this guy named Ralph W. Hood in 1975. It's 32 questions that are thought to measure mystic experience scientifically. Check it out.  


LSD seems to be a powerful gateway toward an understanding of oneself and our role in the surrounding universe and should perhaps be used in that context. However, while breaking down psychological barriers of the mind can be an enlightening learning experience, it should be noted that these barriers exist for a reason. Sounds like with enough LSD use, it's possible to lose your ability to relate to others, to reality, and effectively, to yourself.  

I think a good way to end this post is with this interview from Saul Williams on LSD and how to use it. Smart dude. He's got some good things to say. Have a watch.