This was a triumph

I have been eerily quiet lately (on here anyway), and with good reason. After a very long time of toiling away in the lab, we finally managed to make something that has been eluding us for some time: a Bose-Einstein condensate!

A Bose-Einstein condensate (BEC) is a state of matter that occurs at extremely low temperatures. Other notable states of matter that you may be familiar with in your day to day life are gases, liquids, and solids. Usually the thing that determines what state something is in is temperature, with a fairly strict cutoff between states. The boiling point of water (100 degrees) is a good example. Pressure affects where those cutoffs are, so if you are high up on a mountain, the pressure is lower, and your water will boil at less than 100 degrees.

Not to any kind of scale and blatant disregard for using consistent units.

BECs are cold. Real cold. Ultracold (official term), in fact! They are so damn cold, you can't get anything colder. There is a hard limit in temperature called absolute zero. Nothing can be at absolute zero. It's impossible! However, you can get very very close, and at a billionth of a degree above absolute zero, BEC is a good example. Atoms in a BEC are all as cold as you can get. They are cold because they have very little energy, and they all have the same energy. They act in unison and behave more like waves than particles.

BECs don't occur naturally in the universe (that we know of) because space is much warmer, thanks to the cosmic microwave background. Instead, we have to play all kinds of tricks to get our atoms cold. An experimental setup like this is required for it:

This is around half of the setup.

I suppose you can see why it might take a long time...

Laser Cooling

One of the key techniques used in ultracold atoms experiments is laser cooling. Normally people think of lasers being used to heat things up since they are intense beams of light, so how would you cool something with one? I will answer this question, to spare you tossing and turning all night, unable to sleep because of the inner turmoil of not knowing how lasers can possibly used for cooling.

I'll start with atoms. Atoms in a gas at room temperature move very fast and therefore have a lot of energy, since energy is proportional to velocity squared. Light is made up of photons, which carry momentum that is proportional to the frequency (or colour) of the light. When an atom and a photon collide, they exchange energy. If you get the laser frequency right, then when the photon and atom bounce off each other after the collision, the photon will come out more energetic, and the atom less energetic. The atom is now slower, and therefore has less energy, and is therefore cooler (high temperature = high energy).

There are a few applets at Physics 2000 that let you play around with a few parameters and help you see how laser light can be used to slow atoms down. Check out the rest of the site too! I found it great for learning about Bose-Einstein condensation for the first time, a long time ago...

So far, this is a very simple picture. In real life, things are more complicated. The atoms and photons don't literally bounce off each other. Instead, the atom absorbs the photon and then spits it out again! One might naively think that atoms could be fully slowed to a stop by doing this, but alas, it is not so. There are a couple of limits related to the fact that the atom is always absorbing and emitting photons. However, when physicists hear about limits, they consider them to be a challenge. If that atom won't get any colder, can we trick it into getting colder? The answer is yes.

Have you heard of the legend of Sisyphus? He was a king in ancient Greece who angered the gods, and as punishment, he had to push a huge boulder up a hill, but when he got to the top, the boulder rolled back down and he had to start again. For eternity.

It turns out that by playing some tricks with polarisation, one can replicate this experience for an atom. The atom will always see an uphill potential and will climb the hill. When it gets to the top, it gets transfered into another state and suddenly finds itself at the bottom of a new hill. It looks something like this:

Nicked from here.

This is actually called Sisyphus cooling. You can't stop an atom completely like this (or really at all), but you can make it damn cold! I should note that this is exactly how I feel on Sunday mornings when I voluntarily run up and down a hill for "fun". Try it! You'll love it!

Crackpots

I don't know how prevalent they are in other fields, but physics seems to attract more than its fair share of crackpots. Either that, or I only notice because I'm doing physics. They are mostly harmless, but occasionally they write books and contaminate the minds of the unsuspecting public. (By the way, if you are a physicist or have somewhat of a physics background, check out the free chapter of that book. It's like a sort of physics slapstick comedy.)

I've had various experiences with crackpots over the years. On more than one occasion, ragged, disheveled looking people have wandered into the physics department desperate to talk to someone about their amazing theory that will surely solve some longstanding physics problem or solve the world's energy needs. In all cases, they have little to no physics background and a poor grasp of maths, and they are also very easy to spot from a distance.

I actually (hopefully) managed to discourage one such person. This guy said he had a background in surveying and complained about how current technology for imaging underground was not very good. It's based on blasting sound waves into the ground and then observing their reflections (they do something like this in Jurassic Park). He thought that a far superior method would be to use cosmic rays and that he just needed some help to get his idea off the ground.

Another sort of crackpot exists as well. This is your average person on the street who is not satisfied with (and nearly 100% of the time doesn't understand) a particular theory and comes up with their own. Of course, what they have is just an idea, not a theory as such. I really wouldn't care about this very much at all, but for some reason these people gravitate towards me in social situations. Here is an example of one such situation that took place at a party. I was sitting on the couch minding my own business, when a guy sat down next to me and started making conversation:

Guy: Hi, I'm Bob. How do you know [Party Host]?
Me: Hi. We are students in the same department.
Guy: Oh! So you do physics too!
Me: Yeah.
Guy: Okay, so I have this theory about the universe... I think it's way better than [Standard Accepted Explanation]. Gee, I really like physics, but I never understood maths.

I actually can't remember what his theory was, though I can assure you that it was 100% crackpot. I was in panic mode at that stage, trying to figure out how to politely extract myself from the conversation. Luckily, he got distracted by someone else and went away. Phew. Unfortunately, the next guy who sat next to me proceeded to do exactly the same thing upon hearing that I do physics. I made some excuse, got up and went home. Enough was enough.

I'm told that a similar phenomenon exists in psychology, where people have a driving need to tell psychologists their "theories" about human behaviour. I'm curious about other fields, even non-science fields. Does anyone else have any experiences or funny stories about crackpots?

Lab Tours

Every so often, we give labs tours to high school students. Usually they have an interest in science or are part of a special program. I think walking into a lab like mine can be a little overwhelming for a lot of them. Explaining the physics of what I do is also a little tricky because it's not a topic at all covered in high school, but I do my best to draw analogies with ideas they are familiar with. Some students definitely get more than others. If they are totally quiet, I get the feeling that they didn't understand anything. I consider it to be a good sign if they ask questions!

A few weeks ago, a group of such students came to the lab for a tour. They were part of a group of minority students gifted in science - the kind of kids who will hopefully study science at university. I talked to them a little bit about what it's like to do a PhD (something they didn't know much about), and how it's a lot more practical than studying, doing assignments and taking exams. I also mentioned teamwork. Experimental physics is usually not an isolated venture; it's very common to work in groups of 3 or 4 people on the same project. In my explanation, I happened to say that me and a few other people built up the experimental setup, which involved a wide range of skills.

One girl cut me off.

Girl: You mean you built this yourself??!!
Me: Well, me and some other people. I didn't do it all myself by any means.
Girl: Wow!
Me: ...
Girl: Can you make a TV??
Me: That's more of an electronics engineering thing. Maybe I could assemble a TV, but I wouldn't know how to design all the electronics to make it work.
Girl: Can you make a boom box???

Impress teenagers with your physics skillz. Make a boom box.

Photography Contest!

The local museum runs a wildlife photography contest every year. There are three categories: plant, animal, and human impact on the environment. Last year was the first time I entered, and I won a highly commended prize for this photo:

"Abandoned"

Getting that photo was mainly luck. We were walking on the beach and happened to come across the car. It was late afternoon and the lighting was just right.

The contest rules stipulate that the photo must be taken no earlier than January 2010, and in that time, I have not come up with anything nearly as cool as the car. Out of everything, this is what I came up with and submitted last week:

"Spider on the wall"

"Reclamation"

"Stranded"

"Simplicity"

Click on the captions to get to the high resolution version.

I'll find out how it went in the next couple of weeks!

References

Information spreads quickly on the internet, particularly through social networks like facebook and twitter. Someone learns an interesting factoid, finds a meaningful quote, sees an inflammatory news item, funny video, etc. and immediately shares it with their friends. Very often these tidbits are copied and pasted from friends' status updates or blogs without much thought. I've certainly been guilty of this myself.

It's only natural that misinformation travels through these channels, and it's actually nice to see that only a small portion of shared items (at least from my social group) are blatant conspiracy garbage.

So how can you tell if what you're reading is cow turd, anyway? Read the references! Most of these articles/blog posts/websites have links to the evidence they say backs up their claims. The recent DCA hysteria, documented and debunked nicely in Arstechnica, is a great example of this. It took me about 5 minutes to click on a couple of links from the original page to figure out that this was written by someone who 1) does not understand the process medical treatments need to go through from initial lab tests to treating people, 2) has not done high school level cell biology, and 3) does not have good reading comprehension.

The lesson here is that when you come across something that sounds like a conspiracy or is too good to be true, follow a few links from the source. It doesn't take long to figure out if it's legitimate or crazy talk. Read the references, people!

Antimatter!

I love experimental particle physics papers. They have so many authors! The STAR experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory recently created some anti-helium-4 nuclei. 18 of them, in fact. The effort took no less than 395 authors (+/- 10 or so).

They made the anti-helium nuclei by colliding gold atoms at ridiculously high speeds and detected them in this thing:

They call their detector the Time Projection Chamber. That's the other cool thing about particle accelerator experiments: cool names! I feel inspired to come up with cool names for bits of my experiment, because the current terminology is a bit lackluster. In reality I have "magneto-optical trap" and "science cell", but really something like "atomic decelerator" and "atom interrogation chamber" could make it seem more exciting, or something that makes a cool acronym, like HERCULES or GUNDAM.

Any suggestions? There are lasers and magnetic fields involved, if that helps!

Angels and Demons

Some people get really upset when movies have bad science in them. Despite being a sciencey type myself, I feel the opposite. The more fantastic the concept, the more entertaining I find it. I suppose it's because I take it as a sort of science slapstick comedy rather than the intended movie genre.

Take the movie 2012, for example. Unfortunately it hasn't been ripped to shreds by Insultingly Stupid Movie Physics. Who doesn't want to see a giant tsunami crashing over the Himalayas?

Last night I watched Angels and Demons. It was on TV and I wanted to unwind after a busy day. I'm not a fan of Dan Brown at all. I haven't read his books, but the murder mystery style of the movies is kind of entertaining. For those who haven't seen it, the crux of the movie is that the Illuminati are threatening to destroy the Vatican with some antimatter stolen from CERN.

Now, this antimatter is in a battery powered hand held vial about the size of a water bottle. We are told that the antimatter must be held in a magnetic field or it will just annihilate matter in the container walls. It is true that matter and antimatter annihilate when they come in contact, releasing high energy photons. If you had a milligram, it would be enough for an explosion of the equivalent of 50 tons of TNT. This could potentially be done at CERN with its present capabilities, but it would take 300 billion years to accumulate that much.

There is a nice article at the CERN Courier talking about what it takes to trap antimatter. It takes some very strong magnetic fields, which requires some pretty high currents (since electromagnets are required). So clearly, the hand held antimatter container is highly improbable.

However, this is not what bothered me. What bothers me is that the physicist in the movie says that with their breakthrough in trapping antimatter on a large scale (1 mg), they hope to use it as an energy source to power cities, and not as a weapon. Hold on a second. Their container has a magnetic trap to hold the antimatter. The current for the trap is provided by a battery that lasts up to 24 hours. The magnetic field required to hold antimatter is on the order of several Tesla, generated by superconducting electromagnets. Even if the antimatter is ultracold (like a BEC), you would still need a fairly hefty field. This requires a very high current! Hundreds of amps! Generated by a battery!!

If you have a battery powered device that can trap antimatter, then you probably don't need antimatter as an energy source.

Spider!

The last week has been ridiculously busy, so I haven't had a chance to post! I did make it to the Dunedin Botanical Gardens last weekend for a photo expedition. I was trying to get a particular photo of a flower, but instead, I found a spider:

This one is worth seeing in its original size. You can even make out an eye!

Of Women in Science

A recent post by FSP got me thinking about something. I am well aware that women in male-dominated fields often experience some form of discrimination, but I seriously thought it was an issue well out the door in this day and age. I have never experienced any myself, other than a couple of weird off-hand comments by non-scientists, so I was very shocked to see so many horror stories in the comments of FSP's blog (most of them from the US).

I should also add to this that I didn't know that physics was a male-dominated field until shortly before I started university. I went to an all-girls high school and we had two full physics classes, so one can forgive my preconceptions. As a result, I never expected to be treated differently for being female because I didn't see myself as different from other students.

A pertinent question in physical sciences is why women have not permeated through the ranks as much as in biological sciences. And even then, top academic roles are still dominated by men. So why are their more males in leadership roles anyway? Is a big part of it a generational divide?

In addition to being in a male-dominated field, I also have male-dominated hobbies. I have somehow (unwittingly) ended up in leadership and/or organisational roles in most groups I have been part of (from clubs to academic groups). And you know what? There have always been a disproportionate number of females on these committees. For some reason, they seem more likely to volunteer to organise something or be a club committee member. My experience so far is that most guys prefer to take a back seat and just go with the flow.

So why is it different in the high ranks of academia? Or in business? Do we just have to wait for people like us to grow up and fill those roles?

I would love to hear other people's thoughts on this.

Black and White

There is something I really like about photographing flowers in black and white. In colour photos, there is so much going on that sometimes the subject gets lost in the background, but in black and white it's brought out again. There is something more dramatic about it too!

Of course, I have also taken photos of flower beds in black and white where the petals become indistinguishable from the leaves.

What I really need is a weekend where I am not too busy and the weather cooperates so I can go on a proper photo expedition!

Optical Lattices for Dummies

From the dawn of time, physicists have always been looking for new ways to manipulate atoms. At extremely cold temperatures, it's not quite so straightfoward; one does not simply walk into Mordor contain them in a bowl. When I say "extremely cold", I mean close to absolute zero. Liquid helium is a tropical paradise in comparison. Moreover, usually when atoms are so cold, there are not so many of them. Usually we talk about trapping billions of atoms, and if Bose-Einstein condensates are in question, then a few orders of magnitude less! So solid containers won't work.

Instead, people use magnetic or optical traps, or a combination of both. I'm going to talk about optical traps here. A fun fact about atoms: they can be trapped in laser beams! If you've heard of optical tweezers, this is basically the same thing. The electric field of the light induces a dipole force on the atoms, and they get stuck in the the most intense part of the beam (actually, they can be repelled by the beam as well - it depends on the wavelength of the light).

Now we can get creative! You can do all kinds of stuff with laser light. The nice thing about laser light is that you can make it interfere - peaks and troughs add up or cancel out, and you get something out like water ripples. If you shine two laser beams against each other, they will interfere and produce a periodic structure which we call an optical lattice. If you do this in three dimensions (6 counter-propagating beams, like axes in a 3D plot), you get something that looks like a stack of egg cartons, and in each well you can trap some atoms! If you tune your lattice parameters just right, you can trap a single atom in each well.

There are several awesome things about 3D lattices. One is that they are very much like a crystal structure, so you can simulate a quite different area of physics. Another neat thing about them is that they can be used for quantum computing (at least proof of principle, though perhaps not really for practical purposes - if you've ever seen a cold atoms setup, you'll know why). If you manage to get a single atom in each lattice site, and can somehow manipulate individual atoms, you can make a quantum register with a few hundred qubits!

This brings me to what I actually wanted to talk about: a paper that talks about just this! A group in Germany managed to trap a whole lot of single atoms in a lattice and are able to see the individual atoms (more or less) AND can manipulate single atoms surrounded by other atoms in the lattice! The paper was recently published in Nature (you have to pay to see it, unfortunately, but if you are on a university network, you should be subscribed through your university library). The figures seem to be available, so here is one:

The different patterns demonstrate the level of control they have over the atoms. They can change the spin state of individual atoms and get rid of them if they want to. The result? Pixel art. If it was me, I'd probably draw something inappropriate and see how much I could get away with and still get it published.

Welcome!

I thought it was about time that I make a "proper" blog, something with somewhat themed content devoid of one liners. For some time I have felt the need to contribute to the blogosphere, and this also gives me something to do while I'm waiting for my experiment to run besides facebook and endlessly refreshing news sites.

This blog will include the following:

• Reviews of journal articles I find interesting, fit for the scientifically-minded general public. This has the added personal benefit to myself, because it will force me to actually read more than just the abstract before saving a paper to my massively unread "Papers" folder. I'll endeavor to do one a week.
• Talk about interesting science stuff happening in the world.
• Complain about bad science reporting.
• Occasional nice photos.
• If something interesting actually happens in my lab, you'll hear about that too.
• Whatever else I feel like!

And because I have the word "photos" in the blog title, here is an obligatory cute dog photo: