Explaining the Earth’s Liquid Outer Core

Weekends are lean times here at Science Picks; I see a few dozen new articles a day as opposed to the ~500 new articles per weekday that I get to choose from. Fortunately, some articles/blog posts aren’t news but are just interesting reviews of some aspects of science, so they’re good for whenever I want to share them. So from my bag of saved articles, I bring you:

Why does the Earth have a liquid core? from Starts With a Bang. I really enjoy Starts With a Bang, and I think you should definitely check out other posts from there if Ethan’s style is appealing to you. Also, check out the comments on his blog posts, since his readers have pretty interesting questions and comments as well. Enjoy!

Creating Light From a Vacuum

Quantum theory predicts that in a vacuum, virtual particles are constantly being created in pairs and then quickly destroying each other. Up until now, outside of theory there hasn’t been any proof that they actually exist. Now, researchers have managed to make some of these particles materialize: by giving energy to virtual photons, they created “real”, measurable photons. Did they say “Let there be light!” as they did it? Let’s just pretend so. 

From ScienceDaily:

Chalmers scientist, Christopher Wilson and his co-workers have succeeded in getting photons to leave their virtual state and become real photons, i.e. measurable light. The physicist Moore predicted way back in 1970 that this should happen if the virtual photons are allowed to bounce off a mirror that is moving at a speed that is almost as high as the speed of light. The phenomenon, known as the dynamical Casimir effect, has now been observed for the first time in a brilliant experiment conducted by the Chalmers scientists.

“Since it’s not possible to get a mirror to move fast enough, we’ve developed another method for achieving the same effect,” explains Per Delsing, Professor of Experimental Physics at Chalmers…

The “mirror” consists of a quantum electronic component referred to as a SQUID (Superconducting quantum interference device), which is extremely sensitive to magnetic fields. By changing the direction of the magnetic field several billions of times a second the scientists were able to make the “mirror” vibrate at a speed of up to 25 percent of the speed of light.

“The result was that photons appeared in pairs from the vacuum, which we were able to measure in the form of microwave radiation,” says Per Delsing. “We were also able to establish that the radiation had precisely the same properties that quantum theory says it should have when photons appear in pairs in this way.”

What happens during the experiment is that the “mirror” transfers some of its kinetic energy to virtual photons, which helps them to materialise. According to quantum mechanics, there are many different types of virtual particles in vacuum, as mentioned earlier. Göran Johansson, Associate Professor of Theoretical Physics, explains that the reason why photons appear in the experiment is that they lack mass.

“Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy.”

That’s crazy. What’s the wear and tear like on something vibrating at 25% the speed of light? It’s unimaginable. Whoever engineered that must’ve had an incredibly difficult time.

I was torn about posting this article since on the one hand it sounds awesome, but on the other hand it’s definitely over my head, so I can’t exactly help break it down for you any more than they already did. Anyway, it’s clear at least that this is a very cool experiment and very big news for physics, so let’s bask in this moment of awesome. Are you basking? Bask!

The World’s Lightest Material

Via PhysOrg: Researchers have created a material that’s about 100 times as light as styrofoam. 99.99% of it is composed of air, and the other 0.01% is composed very, very carefully.

“The trick is to fabricate a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair,” said lead author Dr. Tobias Schaedler of HRL.

The material’s architecture allows unprecedented mechanical behavior for a metal, including complete recovery from compression exceeding 50 percent strain and extraordinarily high energy absorption.

“Materials actually get stronger as the dimensions are reduced to the nanoscale,” explained UCI mechanical and aerospace engineer Lorenzo Valdevit, UCI’s principal investigator on the project. “Combine this with the possibility of tailoring the architecture of the micro-lattice and you have a unique cellular material.”

Developed for the Defense Advanced Research Projects Agency, the novel material could be used for battery electrodes and acoustic, vibration or shock energy absorption.

This is very interesting. I’m curious about the ratio of lightness to energy absorption (which they pin at “extraordinarily high”) – simplistically, how proportionally strong is it? If you could make armour that weighed as much as a shirt but absorbed a bullet impact, well, that’d be just dandy. However, it seems like future experiments and applications would be limited by the difficulty of creating this material – mass-producing objects with specific features on the nanometre scale is not yet an easy task. The cost, of course, goes without saying. 

So what does that mean? What does it always mean? We wait and see! In 10 years I’ll want my Macbook 99.99% Air. 

The Race to the Next Heaviest Element

There was news recently about some of the heaviest elements getting their new names. How did scientists discover those elements before anyone else? The University of Oslo has an interesting article on the current race to create elements 119 and 120 for the first time (the heaviest element produced to date is 118, temporarily named ununoctium). 

This kind of science is incredibly high pressure; it’s basically all or nothing. If you’ve spent long years of hard work trying to create this element but someone else beats you to it, your work is basically down the toilet. All research is sort of like this, but some types in particular are after one very specific end goal that only one team will get credit for. 

So what do they have to do to win?

The race to create element 119 started two weeks ago when the nuclear physics facility at Oak Ridge National Laboratory in the USA produced 20 mg of the extremely radioactive substance, Berkelium. Berkelium, which must be created artificially in very special nuclear reactors, is heavier than Uranium and extremely difficult to produce in pure concentrations.

Each of the teams of scientists received 10 mg.

In order to create element 119, they will bombard a metal plate laced with Berkelium atoms with a beam of Titanium atoms. The Berkelium has to be used quickly before it disappears. Berkelium is a perishable substance. It has a half-life of 320 days; i.e. half of the Berkelium will have decayed into some other substance after 320 days…

The goal is to induce a Titanium atom to fuse together with a Berkelium atom.

Titanium has an atomic number of 22. Berkelium has an atomic number of 97. Together, these two atoms have a total of 119 protons; i.e. exactly the right number to create an atom of element 119…

“When the atoms collide with each other on rare occasions, they are usually merely shattered or partly destroyed in the collision.

“However, less than once a month, we will get a complete atom. The probability of doing so is lower than the chance of winning the jackpot in Lotto. The problem is that you will have to detect this one atom on a metal plate where more than 100,000 superfluous events are occurring each second.” …

The only way to do this is to measure the radioactive radiation at the moment when the atom decays.

“This means that we cannot detect the atom by measurement until it is gone. Not before that!” …

The surest way to detect the atom is to examine all of its “daughters” when it decays.
Such a chain of fissions may progress in five to eight steps. The scientists can only be certain that they have found the new element when the chain of reactions occurs in a particular way.

Damn. It sounds really difficult, although I’m glad it’s a simple enough idea for us laypeople to follow. Smash atom 97 and atom 22 together to make atom 119. This begs the question, of course, of why they’d pick this combination and not the other 50+ possible two-atom combos. I’m guessing that’s where the complications that we wouldn’t understand come in, so we’ll have to be happy with what we see here. 

Exoskeletons as Fashion

There’s an interesting article over at the new Discover Magazine blog, the Crux, by Kyle Munkittrick, which you should definitely go read if you’re interested since I’ll just touch on it here. He discusses powered exoskeletons as a coming fashion trend – something I had not at all envisioned. He points out that every fashion is a prosthesis, and most relevantly, glasses and contacts were something first seen only as an aid for a disability, but have now blown up to be very much a part of fashion. Why shouldn’t we adapt to exoskeletons as fashion as well?

Right now powered exoskeletons seem to be mainly considered as aids for the handicapped or for the military, but as they get cheaper and better it’s not hard to imagine them being used in everyday life – there’s plenty of work that requires extra safety or heavy lifting. Hard hats haven’t exactly become sexy, but if it’s something used in a wide variety of circumstances by a variety of demographic groups, and considering there are already a fair amount of companies competing over exoskeletons, it would make sense for companies to try to market their products as fashionably as possible for each niche. 

If you’re wondering about the current state of exoskeletons, below are some examples of modern powered suits in action. Many companies are developing them, but the technology doesn’t seem to be quite developed enough for them to be widespread. Regardless, the exoskeleton seen in the first video (HAL) is being used in over 100 hospitals, according to the Tokyo Times, and the exoskeleton from the second video is being sold for personal use in New Zealand, although it’s currently rather pricey at about $150,000 USD.

Fun fact: the first ever powered exoskeleton was developed by GE and the U.S. military in the 1960’s; it was strong, but too heavy and too difficult to control, so it was never even tested with a person inside. 

And on a side note, the Japanese company that’s working on HAL is called Cyberdyne. They named themselves after the company that created Skynet in the Terminator series, and their exoskeleton has the same name as the homicidal AI from 2001: A Space Odyssey? If they’re trying to tell us something about their future plans, they couldn’t put it any clearer. 

Giant Lake Discovered on Jupiter’s Moon Europa

From National Geographic:

Hidden inside the thick, icy crust of Jupiter’s moon Europa may be a giant saltwater body equal to the Great Lakes combined, NASA announced today.

Lying about 1.9 miles (3 kilometers) from the surface, the ice-trapped lake may represent the newest potentially habitable environment in the solar system—and one of the best prospects for the search for life beyond Earth.

“For decades scientists have thought Jupiter’s moon Europa was a likely place for life, but now we have specific, exciting regions on the icy moon to focus our future studies,” Don Blankenship, senior research scientist at the University of Texas at Austin’s Institute for Geophysics, told National Geographic News…

Similar in size to Earth’s moon, Europa is already thought to house a global, salty ocean beneath its 62-mile-thick (100-kilometer-thick) ice shell. NASA’s Galileo spacecraft, which orbited Jupiter and its moons from 1995 to 2003, first discovered evidence of the ocean…

There probably are many more lakes under Europa’s ice, Blankenship added.

Likewise, the prospects for searching for life on Europa could improve dramatically, as research suggests some of these icy lids covering the lakes may be much thinner than thought.

The techniques they used to infer the existence of the lake are the same that they use with satellite imagery of Earth, for example to discover subglacial lakes in Antarctica.

So when will we finally find out if there’s life on Europa? Uh… not any time soon, it seems. NASA planned a mission to specifically check out Europa using a probe called the Jupiter Icy Moons Orbiter (JIMO), but that plan was scrapped in 2005. This August, NASA launched a probe called Juno to investigate Jupiter; it will arrive around 2016. Taking more peeks at Europa does not seem to be in its job description, but who knows what it might see?

Fun facts: Juno will travel a total of 1.74 billion miles, or 2.8 billion kilometres. If that’s impossible to imagine, well, it should be. Meanwhile, the farthest probe from Earth is the Voyager 1, at 119 AU (an AU being the average distance from Earth to the sun), or almost 18 billion kilometres away. It was launched in 1977 and is still in communication with Earth. 

This news caught my attention because I was just reading about 2001: A Space Odyssey, and the sequels to that novel are based on there being life on Europa. What else did Arthur C. Clarke know that we don’t?

My Thoughts on Free Will and Neuroscience

There have been a few articles written about neuroscience and its implications for free will in the last few days; here’s one in Salon, here in Scientific American, and here from Mind Hacks, which also links to an October article in the New York Times and August article from Nature. 

I’ve found that none of these reflect my own perspective, which is why I thought I’d add my thoughts to the mix just in case you wanted another opinion. Basically these articles portray a struggle over the definition of free will, and make it seem as if some people (namely neuroscientists) find free will soundly disproven while others (namely philosophers) think more evidence is needed. Philosophers argue that neuroscientists are seeing free will as something immaterial, a ghost in the machine, which is not how they see it – free will can coexist with a purely material brain.

My thought is that free will is irrelevant. Free will is an intuitive model for human thinking, a historical assumption. Now we have evidence for another model for human thinking, one based on physics via chemistry via biology. Is there any reason to continue to consider free will as a relevant way of thinking about thinking? I really don’t think so. It may be interesting to philosophers for the moment, but practically speaking what does it tell us? What reason is there for thinking it exists? Whether it exists by one or another definition is irrelevant if it’s a useless, unfalsifiable concept. 

The only point that’s brought up in these articles for the utility of free will is in courts, for assigning responsibility. However, we already acknowledge the flaws of free will in court, via the insanity plea. The idea is that insanity prevents a suspect from using their reason. I don’t think there’s any difference between that case and the case where reason prevents a suspect from using their insanity. There’s this common conception of a “normal” brain and a “defective” brain, instead of the more realistic acknowledgment that every brain is unique and has its own predispositions. Why would a brain we culturally consider defective not have free will, while an equally deterministic “normal” brain has free will? It doesn’t actually make any sense. 

So where does that leave us in terms of legal and moral responsibility? I think it leads us towards rehabilitation instead of pure punishment. The point of rehabilitation is to acknowledge and use determinism – change a convict’s circumstances, change their brain. We just have to realize that this applies to everyone, not just the people we currently don’t think have much free will, like children or the mentally ill.

I could probably ramble on, but I’ve probably made my point clear: free will is, as far as I can tell, a useless concept, and if anything it just obstructs a more effective justice system, as opposed to being the only thing between us and anarchy as some people would claim. I don’t think neuroscientists should be worrying about it at all, given what we know now, so I don’t. 

Robot Can Control a Human Arm

Using electrodes on a human test subject’s arm, a robot could manipulate the human arm as well as its own arms to coordinate an action between them. This is relevant to the pursuit of robots that can assist paralyzed individuals, by using the robot body in addition to helping the paralyzed person move their own limbs. Below is a video showing this robot in action:

 

From Automaton:

The robot controls the human limb by sending small electrical currents to electrodes taped to the person’s forearm and biceps, which allows it to command the elbow and hand to move. In the experiment, the person holds a ball, and the robot a hoop; the robot, a small humanoid, has to coordinate the movement of both arms to successfully drop the ball through the hoop…

“Imagine a robot that brings a glass of water to a person with limited movements,” says Bruno Vilhena Adorno, the study’s lead researcher. “From a medical point of view, you might want to encourage the person to move more, and that’s when the robot can help, by moving the person’s arm to reach and hold the glass.”

Another advantage, he adds, is that capable robotic arms are still big, heavy, and expensive. By relying on a person’s physical abilities, robotic arms designed to assist people can have their complexity and cost reduced. Many research teams are teaching robots how to perform bimanual manipulations, and Adorno says it seemed like a natural step to bring human arms into the mix…

The researchers emphasize that the control of the human arm doesn’t have to be precise, just “good enough” to place it inside the robot’s workspace. They claim that having a robot able to control a person’s arm is better than having a very dexterous robot and a person’s weak, unsteady limb…

He plans to continue the project and adds that they’re now improving the electrical stimulation. They’re now able to move the elbow in both directions, for example. Eventually they hope to move the arm to any point in space.

The basic idea, then, is that it’s difficult to provide assistance to people if they can’t effectively use their own limbs, so why not have their helper robot move their limbs for them? 

I know you’re thinking what I’m thinking: terrifying. Besides that, it should be noted that neurons that don’t get any stimulation for a while can end up dying off, so some paralyzed individuals may not have the option of just getting outside stimulation for their nerves, since they won’t be intact any more. I imagine this solution, activating neurons from the outside, might head that degeneration off if it’s used not too long after the paralyzing event. 

“Lab-Grown Blood Given to Volunteer For the First Time”

From New Scientist:

RED blood cells generated in a lab have been successfully injected into a human volunteer for the first time. This is a vital step towards a future in which all the blood we need for transfusions can be made in the lab, so that blood donors are no longer essential.

Luc Douay at Pierre and Marie Curie University, Paris, and his colleagues extracted what are called hematopoetic stem cells from a volunteer’s bone marrow.

Hematopoietic stem cells are cells that can turn into any kind of blood cell. They’re a step in the path between embryonic stem cells, at the least differentiated extreme, and a specific type of blood cell, at the most differentiated extreme.

These cells were encouraged to grow into cultured red blood cells using a cocktail of growth factors. After labelling the cells so they could be traced, Douay’s team injected 10 billion – the equivalent of 2 millilitres of blood – back into the original donor to see how they survived…

“The results show promise that an unlimited blood reserve is within reach,” says Douay. That blood reserve is needed urgently. Although blood donations are increasing in many developed countries, blood banks struggle to keep up with the demands of ageing populations who need more operations – often involving blood transfusions. And a source of HIV-free blood is essential in countries with high rates of HIV infection…

Douay’s next challenge is to scale up production to a point where the cultured blood cells can be made quickly and cheaply in sufficient quantities for blood transfusions. The 10 billion cells his team made wouldn’t go very far – a transfusion typically requires 200 times that number. With his existing technology, Douay estimates that a single transfusion would require 400 litres of culture fluid, which is clearly impractical. “We are still a long way from the vision of dropping a couple of stem cells into the broth and making endless units of blood,” says John Hess of the University of Maryland in Baltimore.

Douay believes that it may take several years to scale up the technology. Another possibility is to use embryonic stem cells instead, as Lanza did in 2008. “We can generate up to 100 billion red blood cells from a single six-well plate of stem cells,” Lanza says. He also claims to have made red blood cells through yet another technique: generating “induced pluripotent” stem cells from skin samples and coaxing those stem cells into becoming blood cells.

This sounds like great news. Blood donations are always in need; supplementing those with lab-created blood should be a relief for patients in need of transfusions. New Scientist also gave us this handy-dandy timeline of the path to artificial blood, for your learning pleasure:

If you’re wondering what the “Rhesus blood group” it’s referring to above means, it’s a property of different blood types, part of which we’re familiar with by the positive/negative classification of our blood.

Mapping Genetic Expression in the Brain

In this TED Talk (which I found via Greg Laden’s Blog), Allan Jones explains how his team is finding out which genes are turned on and off everywhere in the human brain, and making that information freely accessible. My neuroscience bias aside, it’s pretty interesting and novel stuff, so take a peek. If you have a short attention span like me, there’s a cool animation starting at 2:55 that might suck you in more than the preamble does. 

How does this work? He hinted at it, but I don’t think he was perfectly clear, so I’ll fill in the steps to the best of my understanding. As you may know, RNA (specifically messenger RNA, mRNA) is an intermediate step between DNA and proteins, which, simply put, do just about everything in the cell. DNA is transcribed into mRNA, then mRNA is translated into proteins. mRNA is produced when the protein it codes for is needed, so measuring the presence of certain mRNA can tell you what proteins are being made in a cell. This is the point of this line of research.

Firstly, they get a brain from a recently deceased individual, so that the RNA currently in the brain sample does not degrade before they get to it. They dice up the brain using a cryostat and then cut it even more precisely using a laser, mapping the anatomy as they go along. They purify the RNA from this now-tiny sample. This RNA they’ve collected and purified indicates which proteins are being made in the cells in this sample – the problem now is finding out what the RNA molecules they have actually are, what they code for.

To discover this, they attach a fluorescent probe, a little glowing molecule, to all of the RNA. They put this fluorescent RNA sample through a microarray. A microarray is basically a solid surface with up to tens of thousands of tiny areas delineated on it in a grid; each area will have a certain DNA sequence of interest bound to it. They put their RNA sample on the microarray, then wash the contents of the microarray off. If an RNA sequence is complementary to the DNA sequence in a given area, it will stick to that DNA sequence (which is stuck to the microarray) and not wash off – and you can see that it didn’t wash off because it’ll be fluorescent. 

Since you know which DNA is in which area, you can see which of them had complementary RNA in the sample, and therefore know which genes were being expressed (made into proteins) in the original sample. Ta da! By the relative brightness, you can also infer how much RNA there is – how much these genes are being expressed. 

The novelty of this TED Talk is that they’re doing this for every tiny bit of the human brain, and mapping it back onto the brain. He shows this at around 9:36 – in addition to an anatomical map of the brain, they’re making a gene expression map of the brain. 

It seems like this could be very useful in future neuroscience research, and since it’s a free resource it could become very common to refer to this to guide future experimentation. The biggest problem I imagine is the variety between people’s brains. Brains vary quite a bit between people, behaviorally and anatomically, so any map of gene expression is going to be difficult to generalize. I’m sure there are some regions that are more uniform than others though, for which this map can already prove useful even with its tiny sample size. 

If you’re still curious about the magic of microarrays, here‘s the National Center for Biotechnology Information’s primer on them and why they’re very, very important, although their example doesn’t exactly match ours.