Carbon Dioxide Sequestration Concern

When CO2 is stored underground, it includes oxygen atoms. What is the impact of taking all that oxygen out of the atmosphere?

I am not expert in this field, but I have two thoughts on the matter. First, there is much more oxygen in the atmosphere than carbon dioxide. The amount of CO2 that needs to be removed from the environment, while it may be an enormous amount of substance, actually represents a small fraction of a percent of the atmosphere. Meanwhile, the atmosphere is about 20% oxygen, so that sequestering that CO2 will have much less effect on the proportion of oxygen than it will on the amount of carbon dioxide.

Second, the oxygen in that CO2 is already bonded in the molecules, so it is not oxygen we can breathe anyway. We can't and we wouldn't ever want to eliminate all the CO2 in the atmosphere. That would bring on other disasters such as the stopping of photosynthesis. The object of carbon sequestration is to try to balance CO2 levels against our consumption of fossil fuels. If there is a threat from the loss of oxygen in the atmosphere, (I don't think there is.) the culprit is the combustion of fuel for our energy.

Atomic Theory History Question

Did the Greeks discover atoms?

Democritus lived about two hundred years before Aristotle and Plato, and is often credited with originating the concept of the atom. He was a philosopher, and his idea was to try to explain why different materials had different properties, such as why are liquids flexible and solids less flexible. We know now that the atoms, for example in ice, water, and steam are all made of the same kinds of atoms. Many Greeks of the time thought that the highest form of research was thinking about things, because the mind and ideas are superior to the world and the senses, or something like that. The word "atom" means indivisible, and in that sense, the Greeks were sort of correct. I would argue they really had no idea what atoms really are.

John Dalton, in the early 1800's, more than 2,000 years after Aristotle, formulated the first modern version of atomic theory, and by then he had enough scientific data to actually do a pretty good job of describing an atom as we now understand it. Still, there was no direct evidence to prove the existence of atoms, and Dalton's atomic model was primitive by modern standards.

It wasn't until 1905 that Albert Einstein published a paper that actually proved the atomic theory, and even since then, the model of the atom has been corrected and improved many times. Murray Gell-Mann, a physicist who lives in Santa Fe, won the Nobel Prize in Physics for his research into the inner structure of protons and neutrons.

Teenage Brain Question

As a middle school teacher, I heard many times that the frontal lobes reorganize themselves during adolescence. This is used to explain why teenagers make bone-headed decisions, and as a caution to kids not to mess with drugs or injuries during this period. Your question set me to looking for some quick concrete information. There are many books on the subject, but I found an interesting page on the National Institute of Mental Health website. 

http://www.nimh.nih.gov/health/publications/teenage-brain-a-work-in-progress-fact-sheet/index.shtml

The NIMH paper reports research saying that there appear to be two major growth spurts of the human brain, one around the time of birth and another shortly prior to puberty. It further suggests that each of these growing periods are followed by a pruning process, while the brain decides which of the new connections are important and which are not. These processes are highly individual from person to person, and they say that it is difficult to make generalizations. Research suggests that the growth of white matter in the brain proceeds typically from the front to the back, at the time of puberty. ". . .studies have suggested that gray matter maturation flows in the opposite direction, with the frontal lobes not fully maturing until young adulthood." That it is followed, over a course of years, by a growth or development of myelin sheathing from the back toward the front. Myelin forms on the outside of neurons and enhances their performance.

Neurologists use functional magnetic resonance imaging (fMRI) to watch the brain non-invasively as it performs tasks. It is truly an amazing and exciting technology. Meanwhile I still advise teens to be careful with their brains.

Class Ring Physics Question

Why does a class ring, spun like a top on its stone, stands up with the stone on the top?

You have given this more thought than I have, and a quick Internet search has left me high and dry about the typical inverting toy tops, a wooden sphere with a short dowel. I am also striking out with "class ring physics." I have sent a note to Jostens, one of the major purveyors of these rings, and I will let you know if they have any help to offer. [No reply]

Meanwhile, I do have some information to stir into the recipe.

Unless you went to MIT* or some other institution that doesn't use a stone, the stone has a third or less the density of the metal. (Quartz D= 2.7, Silver D= 10.5, Gold D= 19.3, many gems are based on quartz or closely related to it.)

As to how it would behave in microgravity, I can only speculate, although with all the  personnel who have flown to space, I suspect someone must have tried spinning her or his ring! It would be difficult, if not impossible, by hand, to get a pure spin on the axis of the stone or axis of symmetry of the ring. Therefore, I would wager that the ring would appear to rotate as you have described, but I would also be willing to bet that it won’t exhibit any preference for a particular orientation. NASA had a "Toys in Space" program, and I hope they took a tippy top.

Having just remembered the expression, "Tippy Top," I discovered this amazing page of information. http://www.yorku.ca/marko/ComPhys/TippyTop/TippyTop.html  I am afraid that you will have to explain to me what it means beyond about the third paragraph. :)

*My dad's "Brass Rat" is too worn to spin well, but he doesn't recall seeing MIT class rings stand up as you describe.

Little Boy Replica Question

We were asked why we replaced our Little Boy artifact.

Our current Little Boy model is actually a very faithful fiberglass and metal replica of the bomb that was dropped on Hiroshima. It is even ballasted with concrete to simulate the weight of the original. As such it is a more faithful model than the one it replaced.

Our original Little Boy was built after WWII for the US' nuclear weapons program, but it never carried any active materials, nuclear or high explosive. It was a second generation gun type weapon, and in some ways different from Little Boy. I am told that after 9-11, the National Nuclear Security Administration felt that the several of these objects that were on display (including one at the American History Museum at the Smithsonian Institution) contained more information inside them than the NNSA was willing to share in case of a theft. Some of the weapons they pulled have had their guts removed and are back on display, but the BSM chose instead to have a more faithful appearing reproduction fabricated.

Human Battery Question

You ask if there would be an electrical current if one of the plates were made of rock.

The short answer is no. Unless the rock is a very rich metal ore, rock will not conduct electricity well enough to allow a current.

When we put our hands on the metal plates, we complete a circuit, electricity flows from one plate to the other through our arms and body, and then back to the original plate through the micro-ammeter via wires. The current, which is very small, is caused by the different way the metal plates react to the moisture in our skin; one collects electrons and the other gives them up. Any two different conductors will serve the purpose. Ours are copper and aluminum; but they need to be conductors in order to complete the electrical circuit. The human body is a pretty good conductor.

Most rocks are insulators and can't complete the circuit.

Tritium Questions

Tritium is a heavy isotope of hydrogen having 1 each proton and electron, and 2 neutrons.

You asked, given that it has a half-life of 12.3 years, where does it come from? 

Do we recycle it?

What about the future?

I particularly enjoyed researching these questions. The primary natural source is cosmic radiation striking nitrogen high in our atmosphere. In the same reaction that creates carbon-14, allowing us to use radiocarbon dating of formerly living tissue, tritium is the other product. (I am amazed.) This production is slow enough and the half-life is short enough that there is only a trace of natural tritium in the atmosphere. (Carbon-14 amounts to about one trillionth of all the carbon on Earth and is much more stable than tritium.)

Tritium can be produced in nuclear reactors by exposing isotopes of lithium and boron to neutrons. The actual reactions are described in Internet articles, but I won't pretend I can explain them.

A physicist friend of mine tells me that for the most part, the U.S. is not making new tritium, but rather recycling it from the stock left by decommissioning weapons. This supply is slipping away as we use it and as its half-life dictates. Jim said that there are several ideas for eventually replenishing our supply using particle accelerators or nuclear reactors.

My personal favorite tritium factoid: Willard F. Libby, one of my all-time heroes, the developer of radiocarbon dating, used tritium for dating the water in wine. I suppose most wine is too young for carbon-14  (Half life ~5730 years) dating. (The United States requires that wine be slightly radioactive, but that is a different discussion.)