Explosions!

Today I attended a physics colloquium; every Tuesday they bring in someone to talk about physics research or a physics topic. Today it was "Recreating Astrophysical Explosions with Combustible Gases in the Laboratory."

Stars are giant fusion reactors, but they mostly convert hydrogen into helium. The heavier elements come from when a star 'dies' and explodes, in an x-ray burst, a nova, or a supernova. The particular system that today's talk was looking at was accretion driven explosions, which happen in binary star systems. Often, in a binary star system, one star will collapse into a neutron star or a white dwarf-- a highly massive, but very small star-- and the other will burn itself out and expand becoming a red giant. When this happens, material from the now much larger star will be attracted to the smaller one, and will be captured by this. As this happens, the small star, due to its compact state, will no longer act as an ideal gas-- when more matter is added to an ideal gas, temperature will rise and volume will increase, which will then cool it back down. In a degenerate star-- that is, the white dwarf or neutron star-- pressure will increase instead of volume. As more mass is added to the star, the pressure rises, increasing the temperature, which then increases pressure again, which then increases temperature; rather than the star cooling itself, it creates a runaway reaction. In this environment, temperatures are such that nuclear reactions compound, and heavier elements are created.

When a nuclear reaction like this happens, many, many transformations happen; an element is created, and before it can decay back down to a more stable state, it will be bombarded again and instead raised up to a new, heavier element.

It is impossible to create this sort of cascading reaction in a lab; the temperatures and pressures required are only present in these super-compact degenerate stars. Creating something like this on Earth would be catastrophic. What we can do, and what our laboratories are trying to do, is create the individual reactions in the cascade, one at a time.

Here is where the talk got really interesting; as much fun as the theory is, it is fascinating to see how these things are actually done.

The Oak Ridge National Laboratory, where our speaker was from, has an enormously complex setup, and I cannot speak about it in great detail because, to my dismay, I don't understand a lot of what it all does. I'll tell what I can, though. They have a cyclotron that produces radioactive ions, which they then send to a massive tower to accelerate them. The principle is fairly simple. They have a huge electromagnet, the top of which they set to positive. The negatively charged ions accelerate upwards towards it. At the top there is a carbon stripper foil; when the ions pass through it, the density and energy are increased, so they can no longer sustain as many electrons. Thus they are turned from negatively charged ions to positively charged ones. Now positive, the ions accelerate bock down the tower, to be directed into the appropriate mechanism from there-- depending on what sort of ions they are, the facility can direct them to a number of places. Today's talk focused on the Nitrogen 17 to Neon 18 reaction, so that is the only set up that we heard about.

In order to create the reaction they wished to measure, they needed three things: Nitrogen 17, Hydrogen, and a lot of energy. Above I discussed briefly the setup to create the high-energy beam of Nitrogen 17; now I'll talk a bit about the Hydrogen. The ORNL facility uses an extremely low pressure gas chamber, with multiple pumps set up to keep the pressure low. The pumps have to create a constant pressure for the gas window, as it is called, so that their measurements will be consistent. The benefit of having these pumps, the speaker told us, was that it doesn't take a whole lot of time to get the machines up and running; this is aided further by the fact that they are being used to lower pressure, rather than raise it.

So now we have a beam at high energy being focused into a target, of the right elements. This will produce the reactions desired-- though not very often. For every reaction produced, you need as many as 10^12 particles to pass through the window. Now we need to filter out the non-reactions so that we can measure the ones we want to look at. This particular reaction emits a gamma ray along with producing the Neon 18; unfortunately, gamma rays do not have a lot of momentum, so the reactions are barely deflected. However, they are at different enough velocities to be filtered that way. Directly after the gas window in the setup is a recoil separator. This device has two functions: it will re-focus the slightly deflected atoms back to where we want them, and it will only allow atoms traveling at a specific velocity to pass through it. The first is accomplished by magnetic fields that are vertical-- perpendicular to the path of the beam-- and the second by electric fields that are horizontal. The parts of the beam we don't want to look at can be deflected away, and only the one we do want passes through.

After that there is a dipole magnet that deflects the beam at an angle, measuring the momentum of the atoms. Now that we have both velocity and momentum, we can measure the mass, to be sure that we have what we wanted to create. There is also a detector that measures energy loss, which will yield the atomic number, after some calculations.

So! We have created a reaction. Now, what can we learn from it? After plotting the data, we can see the resonance strength-- the bell curve will either have a very steep slope, or a more gentle one, and that will show how sensitive the resonance is. (I'm not going to try to explain resonance at the moment; it has to do with quantum energy states, and I do not feel confident enough in my understanding to say much about it.) The resonance strength, it turns out, is directly proportional to the reaction rate-- and that is a very useful thing to know. This particular reaction, for example, has a half life of about 2 hours. This is long enough that we can measure it, with satellites, and based on those measurements, we can figure out what the star was like before it went nova.

If we can get accurate data for every one of the reactions we can produce in a lab, we can extrapolate the more high energy ones from the data. When we have a thorough understanding of every reaction that takes place in a star's explosion, we can create a more accurate model of a star's life. And as I have mentioned before, models are extremely useful things.

A Box for Fluffy

For one of my classes this week, we started playing with Simile, a box modeling software whose "Evaluation" edition allows for fairly simple models to be built.

A box model is a simplified way of looking at a system, with boxes for reservoirs and fluxes to show what goes into and out of that reservoir. For example, a model of a lake would have a flux of the stream that feeds it going in, as well as one for rain, and would have one going out for evaporation. In complex systems, these are incredibly useful tools, and with software to do the calculations, you can see how a system will behave over time-- they are used to project into the future, and see what is likely to happen.

As with anything that purports to predict the future, there are some caveats. First and foremost, it is based on statistics; you can say that in a hundred years you will have a certain number of major floods, for example, but you can't say when they will happen. Second, a model is only as good as the data you put into it. If you know every single factor that feeds into a model with perfect accuracy, your model will be very, very good. But there are very few cases where that is true.

The first model we worked on was a wonderfully silly little thing involving, to quote the book, a "fairly fragile finicky freshwater fish" named Fluffy. Fluffy has to have flowing water to live, so we were designing a 'tank' for him that had water flowing in through the top and out through a hole in the bottom. If the water level went too low, Fluffy would die. If it got too high, it would run over the top and Fluffy would die. So we created a box model where we could vary the amount of water flowing in, to see where it would reach equilibrium.

For homework, we are working on something a little more complex: global temperture. Our models are going to be much, much simpler than the ones they use to predict climate change. The first one is based solely on the temperature of the oceans, which are, for the purposes of our model, assumed to be evenly distributed on the surface of the earth, at a consistent depth. The only reservoir is Earth's energy, the only inflow is solar radiation, and the only outflow is infrared radiation back out into space. This will remain the same, no matter how complex the model gets. For this model solar radiation doesn't change; in reality, it does. For this model, infrared radiation is based on the temperature of the ocean, which is based on the amount of energy in the Earth reservoir, which is based on solar radiation and infrared radiation into space. As the energy in the system rises, the temperature rises, but as the temperature rises, the amount of heat radiating out rises as well, which lowers the energy of the system. It will reach an equilibrium point.

Unfortunately, I am having trouble with my model; I think I put everything in correctly, but the system did not even out. I'm going to have to work on it some more. It gives me a new appreciation for the models they actually use in science; if I have difficulty with such a simple model, what must it take to make a really complex one work?

On the bright side, every new model that is proposed is better, more accurate than the last. We're getting better at it. And that means our predictions are getting more accurate. And that is always a good thing.

"I had no need of that hypothesis"

The above is what Pierre-Simon Laplace said to Napoleon when asked why his book on astronomy, unlike Newton's contained no mention of god. Newton had seen that his calculations were not entirely accurate, and had decided that what kept the planets from careening out of place was the hand of god. Laplace made some corrections, and was able to explain celestial motion without resorting to the supernatural.

I think that quote-- "I had no need of that hypothesis"-- is an important one. The more we learn about the universe, the less we need the supernatural to explain anything. There was a time when we did not understand much, and at that time, gods arose. What caused the lightning, or the rain, or the lack of it? An angry god, punishing the wicked. Likewise, favorable weather was caused by a happy god. Appease god, and things will go well. We know now about pressure systems and how weather works; we no longer have need of that hypothesis. Before Darwin, we had no idea how life came to be, in its many and varied forms. It was reasonable, then, that people believed god had made all the plants and animals, shaped them as an artist might. But Darwin saw a more reasonable way it could have happened; following the natural laws of the universe, life could have evolved to the state in which we now know it. And again, we now had a natural explanation, and have no more need of the god hypothesis. It is no longer reasonable to think that god did it, any more than it is reasonable to believe god causes the weather. We know how life came to be in its present form; we have no need of god.

As science advances, the need for god retreats. What once was seen as the vagaries of an all-powerful deity is now known to be simple cause and effect. It was, I think, simple cause and effect that led me to reject the idea of god. When you pray for something, and it happens, where, exactly, did god step in to give it to you? Say you prayed for a parking spot-- I know plenty of people that pray for that very thing, and other inanities. When you get to the store, there is a spot right up close-- your prayer was answered! But where did god come in? You left the house at such a time that when you arrived, someone else had just left. They left because they had an appointment to get to. That appointment had been set a week before, long before you prayed for that parking spot. Every effect has a cause, traceable by the laws of nature. Where is the need for god?

Some might say that god 'inspired' them to leave the house at the precise time they needed in order to get that parking spot, or 'inspired' the other person to leave at that time, but that falls apart too, if you think about it. Everything you did that day, including your thoughts, had a physical cause. We do not yet fully understand how the brain works, but we do know that thoughts are physical, chemical reactions in the brain. There is no need for a divine finger in your grey matter; you had that thought as a result of what came before.

So there is no need for a god in our day-to-day lives-- and, in fact, god cannot exist there. Everything follows physical laws. A miracle, were one to occur, would break those laws... but there is no evidence of anything breaking them, ever. There are no miracles that have been verified by science as having happened.

What about creation? Well, Darwin put paid to god creating life as it now exists. Abiogenesis-- that is, what sparked life in the first place-- is another matter... but given everything that we now know, it seems silly to simply say "god did it" when we could instead work on the problem and try to find out. And scientists are doing just that. There is no reason to believe that this one thing required a divine touch, when everything else can be explained by science.

And I do mean everything. We know how the planet formed, how stars and galaxies form. We've even got a pretty good handle on the Big Bang. We don't know exactly what sparked it... but there is reason to believe that we do not need a god, even there. I have just enough of a handle on the physics to put it very simply; I don't know it in great detail, but it is an explanation I got from Stephen Hawking, and I know just enough to find it reasonable. The universe, at the moment of the Big Bang, was infinitely small-- small enough, in fact, that it falls into the realm of quantum mechanics. In quantum mechanics, particles do not have a linear sort of existence; they pop in and out of existence, for lack of a better term, all the time. It is therefore not inconceivable that the universe itself, at the time a quantum particle, could have simply popped into existence. No need for that hypothesis, indeed!

But it goes further than that; with what we know of the Big Bang, and of the universe, it seems there is no place for god, period. To begin with, you have to understand that time, like space, is a physical dimension. We exist in a universe of (at least) four dimensions, three spatial, one temporal. This is known as space-time. Space time, it has been proven, can be warped; the most stunning example is that of a black hole. If you were to fall into a black hole, and could somehow survive to observe what was happening around you, time would slow for you, and eventually come infinitely close to a stand-still; you could look out at the universe and see eons flying by. So, time is a physical dimension, contained within the universe, just like space. When the infant universe popped into existence, it contained time, as well as space. Therefore, before the Big Bang, there was no time. Asking what happened before the Big Bang is like asking what is north of the North pole; it is a meaningless question.

Without time, without a before in which to exist, there could not have been a god before the universe that could have created it.

Some people will say that god is eternal, existing outside of time and space; such a god seems pointless to me. In order to influence the universe, whether by creating it, or life, or by intervening in people's day to day lives, god must be part of the universe. If god is part of the universe, then he is bound by the laws of nature (having been created by the Big Bang himself), and cannot violate them, and he cannot have existed before the Big Bang to do any sort of cosmic on-switching. If god is outside the universe, he cannot influence it.

There is just barely room, if you wish to see it this way, for the deist god. It is possible that, in whatever existed before the universe, whatever currently exists outside the universe, there was a being who could have caused the particle-universe to pop into existence. Such a being is not known to have ever influenced anything inside the universe, and so in my mind, speculating about its existence is meaningless. We can only know the universe, at least so far in our understanding. Who knows? Maybe someday we'll reach outside that boundary, beyond what we now know as existence, and find something else there. Since we cannot assume that what lies outside the universe obeys the same natural laws, I suppose things found there could be called "supernatural." Somehow, I think that kind of supernatural would not be very satisfying to many theists.

Little green microbes?

Life on Mars Found by NASA's Viking Mission?

Science reporting in the news is always a bit sketchy; a reporter gets more attention by making bold claims than by reporting on maybe and possibly. Whenever you read in the news about a scientific discovery, it should be taken with a sizeable grain of salt. Even so, this one is pretty damned cool.

Back in 1976 there was some evidence of life-processes taking place in Martian soil. Now, researches have done some math and found that those life-like-processes seem to be on a circadian rhythm that is consistent with the length of the Martian day. What does that really mean, though?

The search for life on other planets is a difficult thing; we can't know how similar or different it would be from life here on Earth. We can make some assumptions-- it would probably be carbon-based, simply because carbon is so abundant and so easy to combine with other things. All the life we know of is carbon-based. Some scientists have thought that if a life form existed that was not carbon-based, it would probably be silicon-based, simply because silicon has a lot of the same properties as carbon. But we don't know-- biologists, for this purpose, have a sample size of one. All the life they have ever observed is terrestrial life, carbon-based and built on DNA. Would life elsewhere be the same?

Some people think that life on Earth began when a meteorite from Mars crashed here and brought Martian life with it. If that is the case (and it is possible, though a little improbable), then life on Mars would be very similar to life here. We could assume that it would have DNA and be carbon-based and be very like the life we have here, just evolved in different ways. But what if it didn't? What if life began twice, in our solar system? Life on Mars needn't have anything in common with life on Earth. It probably would have some similarities-- I mentioned carbon above, and there are other factors that are similar enough on Mars and Earth that some things would likely be the same-- but we couldn't make any assumptions.

So how do you look for life? The original 1976 results showed that a Martian soil sample reacted the way one on Earth would, if that Earth soil sample contained microbial life. They ran several control experiments as well, which would not have elicited a result with the life-rich Earth soil, and they failed to do so with the Martian soil, either. How many assumptions are inherent in that test? Is it possible something other than life could have produced that result? Is it possible the rover brought microbes with it, and they contaminated the experiment? Too many factors, too many unknowns. But one has been eliminated now. It is not possible that Earth microbes produced the result-- Earth microbes would have had a different circadian rhythm. The fact that the results showed a circadian rhythm that would be consistent with the circadian rhythm Martian life would have if it did exist is fascinating, but is not proof of anything.

Is there life on Mars? Possibly. That's the best answer we have for now. The possibility has not been eliminated, and there are some tantalizing results that indicate that it might be true. And that's pretty damned cool.

LASERS and SPACE and SCIENCE!

Yesterday I got an email regarding internships at the Mines Center for Space Resources, for which I am hopelessly underqualified but for which I am going to apply anyway. One of them involves working with Laser Induced Breakdown Spectroscopy. I've talked before about how neat lasers are, and I've mentioned that some time I should blog about spectroscopy. This is the perfect opportunity to do so!

Spectroscopy is a method by which we can tell the chemical composition of something based on the light it emits. Which is really neat, because all we have from outer space is light-- well, electromagnetic radiation, actually, but it's the same thing. It's not like we can send a probe to a star to test its chemical composition. We have a hard enough time sending probes to Mars! But using spectroscopy, we can look at the light a star-- or any celestial object-- emits (or reflects), and we can see what it is made of. That, to me, is freaking COOL.

To understand how it work, you have to have a little bit of quantum mechanics. That might seem scary, but it's really not that bad. Imagine the simplest atom you can, a hydrogen atom. It has one proton, which makes up the nucleus, and one electron, which orbits that-- sort of, but there's no reason to equivocate on that topic today. The electron, it turns out, can have different energy levels. What's interesting is that they are distinct-- it's like if your car could go zero, five, ten, and twenty miles per hour, but nothing in between. You would be stopped, and then without transition, you would be moving. These energy states are called "quantized" because they have distinct, specific quantities. This is why the word "quantum" came to be used for subatomic physics.

Anyway, you have one electron, and it can have several different, distinct energy states. If the atom is excited-- that is, energy is introduced, and the atom absorbs it-- the electron will pop up to one of the higher levels. But an atom does not like to stay excited for long, so soon enough, the electron will pop back down to a lower level, and when it does that, it emits a photon-- that is, a light carrying particle. It gets rid of that extra energy in the form of electromagnetic radiation. And because those energy levels are quantized, so are those emissions of light. If you were in your quantized car, as described above, and you wanted to drop from twenty miles per hour to zero, you would have to get rid of a lot more energy than if you went from twenty to ten. So it is with the electron. The more energy it needs to emit to get back to a lower level, the higher frequency light it will emit.

The electromagnetic spectrum is huge. It goes all the way from radio waves, whose wavelengths can be as long as football fields, to gamma radiation, which is so high energy it's extremely bad for you. Right in the middle, a tiny sliver makes up the visible spectrum of light. At the 'top' with the highest energy is blue-- a little bit more energy, and it goes into ultraviolet light, which we can't see without help. At the 'bottom' with the lowest energy (and longest wavelength) is red-- a little bit less energy, and it goes into infrared, which again we can't see without help. Between the two are the colors of the rainbow. When we see colorless light, we are seeing a blend of those wavelengths.

So our hydrogen atom's electron is bouncing around, as quantum particles are wont to do, and it is emitting photons whenever it jumps down. It turns out that four of those emissions are in the visible light spectrum. When we view light emitted from excited hydrogen, we see four distinct lines. And it turns out that no other element has those exact lines-- in fact, every element has its own set of distinct spectral lines. We can even see it if the electrons are jumping up instead of down-- they absorb light, so there will be a dark line in that element's signature places. Now we have a means of telling what kind of particles emitted the light we are seeing-- or, in the case of absorption lines, what the light bounced off before it reached us.

How cool is that? We can look at the light from a star millions of light years away, and we can do a little math, and say for certain what that star is made of. SO COOL.

Now, a little bit about Laser Induced Breakdown Spectroscopy. It's a lot easier to do this sort of thing when you have a burning gas then when you have a solid-- everything emits radiation, but it's not usually in the visible spectrum. So what do we do, if we want our Mars rover to be able to tell what something is made of? We either give it a big fancy chemical lab that can do all sorts of tests... or we give it a high-powered laser. Curiosity, which is on its way to Mars currently, has such a laser. When it lands, it will be able to point that laser at a rock and vaporize a tiny part of it, energizing those atoms in the process, and from there, it can read the spectral lines. It doesn't have to pick up rocks or do complicated chemical tests. It just zaps a rock, which can be however far away, and analyzes it from there.  How cool is that?

I love my school-- I have an opportunity, albeit and unlikely one, to work with this really cool science that I am so fascinated by.

Also, science is AWESOME.

Space!

... industry, that is.

One of the many things that makes my school such a special place is that we have recruiters looking to hire students as interns, part-time, and full-time, at all times, and at all levels. There are events at least weekly for different industries and companies, and our online job search/application engine is updated daily, with almost universally industry-related positions. No retail or food service jobs on DiggerNet, save the on-campus ones.

So today there was a workshop about finding and getting jobs in the aerospace, DOD, and aviation industries. Lockheed Martin, United Launch Alliance, Sierra Nevada Corporation, and SEAKR Engineering had representatives there to tell us how to stand out among applicants, and what they each had to offer. First of all, I love that campus recruiters come to Mines to sell themselves to the students. They know we're the best, they want us. It's great.

Second, I find it amusing that even though the event said it was also for DOD (that's 'department of defense' if you were wondering) and aviation, everyone there-- organizers, campus recruiters, and students alike-- knew that we were all there because SPACE. One of the ULA guys even put it that way: "Why would you want to go into mining when you could be working in space?" It amused me, and rocketed (pardon the pun) ULA much higher on my list of people to seek internships/employment with in the future.

Again and again, the recruiters told us that while CU Boulder has an Aerospace Engineering department and Mines does not, they would much rather hire a Mechanical or Electrical Engineer from Mines than the Aerospace Engineer from CU. Again and again, we were told that they didn't care if you had a 4.0 (though below a 3.0 and you're SOL), so long as you had shown leadership and teamwork and enthusiasm. Again and again, we were told that we should start networking early, so that when we are ready to graduate the hiring managers already know who we are.

And I thought: yeah, I've got a pretty good chance. I'm at Mines. I'm the founding president of a campus organization, involved with another that has ties to a national professional organization, and I am extremely excited not only by space, but by pretty much everything I do. And I've still got a few years left. So I decided I should ask a question, put myself out there, make sure they at least notice that I am there. In retrospect, what I asked was probably a very good question, indeed.

I was, in fact, the first student to volunteer a question, which looks good enough on its own. What I asked was simple: I am majoring in Engineering Physics. This is not strictly an engineering degree; it's a BS instead of a BE. As a result, it is sometimes hard to find job listings at companies like those present today. What kind of opportunities did they each have for someone in my program?

This made some of them a little uncomfortable, I fear. Several of them told me, either then or later, that they loved Engineering Physics majors, we were better qualified than engineers from other schools and more able to think abstractly about a problem than many engineers. One of the ULA reps told me that he thought it was a mistake that they had not opened their internships to physics majors this year, and he hopes that is corrected in the future. A guy from the space research center on our campus told me that he thinks engineering physics people are his best employees.

But the crowning glory was the rep from Lockheed Martin. She, again, was a little uncomfortable, because not only did she feel that there were plenty of opportunities for those in my major, she also did not know any of them off the top of her head. So she gave me her card and asked me to contact her; she would ask one of the hiring managers what I might look for and what I could do to stand out as an applicant. She asked whether I had applied for any of the internships this year, even, as they do hire as young as freshmen. I told her no, but that I would likely be looking next summer.

Before the ULA has an info session next week, I believe I will attempt to create a resume to give to them.

Tesla coils and a (small) herd of cats

Every spring the Colorado School of Mines takes a weekend to do nerdy things in celebration of E-Days, which is of course short for "Engineering Days." They have a mining competition, pull and ore cart down main street to downtown Golden, build cardboard boats and soapbox cars and trebuchets, and cancel classes for a day and a half to do it. Most of the really neat stuff-- in fact, all of the things I just mentioned-- are tomorrow, but today they had a tesla coil demonstration, and it was awesome.
Tesla coils, for those who do not know, are entirely useless but very cool things which create electrical arcs through the air. That's it. You turn it on and there's lightning arcing up into the air. Or, if there are two of them, across the gap. Useless but very cool. Well, not entirely useless-- some people have managed to turn them into musical instruments, which is awesome. Go to youtube and look up Arc Attack, you'll see what I mean. Anyway, this guy brings in one he built at home, and tells us about Nikola Tesla (look HIM up on "Badass of the Week" for an entertaining read) between turning the thing on and showing us neat stuff it can do-- like putting a little spindle on top with a wire balanced on it, and having the heat from the electricity now arcing off the ends of the wire cause it to spin. Then he let us come up and see the guts and ask questions, and that was awesome, too. Tesla coils are neat, and I want to build one.
Following that I managed to meet up with several of the people I am hoping to organize the SSA group with. The saga continues: we heard from the elusive Matt again, and this time we have a LOCATION for the Tuesday meeting! Hopefully I will yet manage to collapse the wave-function that is Matt, and find out whether we can get all our cats to herd together in a single group. Even so, I met with Nate, one of the people I found while fishing with my button, and two others that are not students but are still quite interested and helpful. We decided that we would like to be sure we are all on the same page before Tuesday, so it's more like two herds of cats coming together, rather than each cat having its own ideas. (At some point I will get tired of calling them cats. That has not yet happened, obviously. I do not anticipate it being soon.) The good news is: the people I met with today are very much on the same page as me, and are people I know I can work with. I hope my observation of the elusive Matt collapses him into a favorable quantum state as well.
We talked about a lot of things-- speakers we would like to get, and a few we might be able to afford sometime soon, ideas for service projects, what our group's official structure should be, good things to include in a mission statement, fun events we could plan on campus, and more. Here is our proposed mission statement at the moment:
"The Secular Student Alliance at the Colorado School of Mines strives to create an welcoming environment for students who embrace a non-religious or skeptical worldview. Our group works to utilize debates, discussion, speaking events, service projects, and cooperation with faith groups on campus to generate a dialogue about supernatural claims, science, ethics, skepticism, and reason."
Hopefully, when we arrive on Tuesday, this will all gel with what Matt and his herd have been thinking, and we can get things moving forward.

Museum hijinks

Tonight the museum (and by that I mean the Denver Museum of Nature and Science) had a sort of "welcome new members" event, where they opened up after hours and had special presentations and other cool things. I love the museum, and my boyfriend recently got us a membership, so we went, and it was awesome.

First things first, we got there just in time to hear one of the resident space scientists talk about Mars, and the latest mission to Mars, which will be landing there (with the newest, biggest, shiniest Mars rover yet!) on August 5. They're going to have an event at the museum that night, and I am pretty sure I have to go. SO COOL. (A word about me: remember how excited I was about the LASERS? Well, I like SPACE even more.) It's nuclear powered! He talked about the evidence of liquid water on Mars in the past, and research being done about it.

Then we wandered about in Space Odessy, the museum's space exhibit, for a while. We were going to see the planetarium show, but the line was ridiculous and it is a regular show we can go see some other time-- not for free, but we can. So we checked out the meteorite cart, and of course I had to show off the spectroscopy cart-- spectroscopy is NEAT and I will blog about it another time-- and while we were doing so, we are visited by... Galileo!

Galileo is, of course, a museum staff member dressed in a silly hat with a platic telescope, and they have this whole skit where a volunteer thinks Galileo is just a disruptive visitor (he's making quite a scene) but the crowd cheers for Galileo to do his experiment-- what he calls the "leaning tower of pizza" experiment, with a big ball and a baby ball, to see which one falls faster. This is all very much for kids, and also awesome. The volunteer says "hang on, this isn't an experiment, we need a hypothesis!" and gets the kids to guess which will hit first. He then talks about how he is a SCIENTIST so he cannot merely THINK through a problem, he has to TEST it. Bravo! And so he drags out a ladder, and a kiddie pool, and it is revealed that his "big ball and baby ball" are in fact water balloons. He gets two people to help him-- he just calls them Kid and Other Kid-- and the volunteer stops him again: they need safety equipment! So the kids put on raincoats and goggles and shower caps, and Galileo takes off his glasses, and then he climbs the ladder and-- what do you know, they hit at the same time! The whole thing was hilarious and awesome.

Then we go to where they've got the backroom of the zoology collection open-- somewhat-- to the public. We get to see some of their invertebrates, and the attack beaver, and bats of every size, and a black rhino skull, and then we went into the room with the bugs and spiders and I had to move on a bit quickly because the brown recluse looked disturbingly like a spider I saw in my apartment last year and that creeped me out... but the giant bird eating tarantulas were neat, and the camel spiders are in fact really freaky looking. After those were the flesh eating beetle colonies. Turns out this is how they clean the specimens-- they skin them, and the skin gets put in the collection elsewhere, and then they throw them in a big box with flesh eating beetles, which clean them down to the bones, without damaging the skeletons. They even have a little taster tank-- if they suspect a specimen might poison the beetles, they throw it in there, first, to see if it kills the few they keep separate. So cool.

At that point we realized we were running out of time-- with me being all about SPACE and my boyfriend studying biology and zoology specifically, it's no wonder we got very distracted by those. We dropped in and saw a little of everything, picking up some swag along the way-- buy one get one free coupons for the IMAX shows, dinosaur posters, "slothtastic" stickers (which I can only assume are about the Snowmass dig, another cool thing I'll get around to talking about later), one of which has attached itself to my phone. We got to see a little more behind the scenes, where we chatted with a guy who works in the collection, and lots of other neat things that I will have to go back and see when we have more time.

All in all, a fantastic night at the museum.

LASERS

You know what is really cool? LASERS.

I put that in all caps for two reasons. One, not everyone knows (or remembers) that the word "laser" was originally an acronym. It stood for Light Amplification by Stimulated Emission of Radiation. Of course, it has become a word-- everyone knows what a laser is, and it's perfectly fine, grammatically, to write it just like that. I write it in all caps, mostly, because lasers are FREAKING COOL.

Everyone has seen, probably even used, a laser. Laser pointers are common technology (though when I was a kid and desperately wanted one, they were at least $50, I checked), CDs and DVDs are read by laser, barcodes are scanned by laser-- lasers are everywhere. The laser sight on a sniper rifle is such a well known piece of technology that a red dot appearing on someone in a movie is an instant source of tension-- that person is going to be shot!

The scientific uses for lasers are even cooler. The distance from the earth to the moon is measured by bouncing a laser off a reflector left by one of the Apollo missions. Lasers are used in microscopes to image extremely small things with great accuracy. Lasers can cut more precisely than any mechanical process. Lasers can perform surgery where no incision is necessary. They're used in spectroscopy, which is a really cool concept on its own.

So how do they work? Fairly simply, actually. You pump light into a medium that will amplify it, and then focus it out one end as a beam. Of course, it's not as easy as it sounds. You have to find the right medium so the wavelength that you want is amplified, you have to use an external power source, and so on. But really: create a tube, with mirrors on both ends, so light will reflect. Fill it with a gain medium-- it could be as simple as glass or neon, like a neon light, mixed with helium-- and then introduce a light source. For some, it could be an electrical pulse, like the helium-neon mix. For others it's a light, or a chemical reaction. It depends on what you're using as a gain medium. Make sure that one of the end mirrors is partially transparent, so the amplified light can go somewhere, and you've got a laser. Many will then put a cap on the end so that the light can only go out through a small hole, making the beam small and focused.

So, one of the really cool things about studying physics at this school is that there are a lot of opportunities to play with lasers. All of the labs on the top floor of the physics building have warnings posted on the doors about lasers. And we have some really, really cool lasers. We've got one setup that's doing microscopy-- that is using a laser as a microscope-- that literally counts photons, yielding a much clearer picture than other systems that amplify to that degree. They've got one that can give a 3 dimensional image of a fly's brain. But the coolest one is the one doing something unexpected.

They created a setup that focuses a beam in four dimensions-- that is, in the three spatial dimensions, and also in time. If you're not used to thinking of time as a dimension that's going to either sound nonsensical or extremely simple. In practice it is neither; this was quite an accomplishment. So they did what any good physicist would do with a brand new, very cool laser: they pointed it at stuff. One of the things they pointed it at was glass. Glass is an interesting thing-- it is structurally the same in all directions, because it doesn't have any sort of crystallization. It's kind of an amorphous blob, really. So, one would expect that, when carving things into it with lasers, the direction the laser was moving wouldn't matter-- the whole area touched by the laser is affected the same way. Generally, that's true. Not with this one. With this one, they get one kind of mark when moving to the left, and an entirely different kind of mark moving to the right. The conclusion they came to: their laser is somehow tiled in TIME. One side of the laser is hitting the glass slightly before the other. And they do not know why. So now there's a senior design project trying to take pictures of this phenomenon. And succeeding. At taking pictures of LASERS.

My school is awesome.