Archive | September, 2011

Next-door neighbors in space

30 Sep

China is the new kid on the block, joining Russia and America. China has just launched the first module of it’s manned space station, Tiangong-1. It means “heavenly palace.” Also, the Chinese will work together with the Russians to put a rover on Mars in 2013.

Photo from People’s Daily.

Where do the elements come from?

29 Sep

We are all made up of dust. Atoms in bound states create molecules. The right molecules in bound states creates proteins and amino acids. Keep binding and combining and you eventually make your way up to cells, organs, people. Every miraculous bit of us is formed from atoms. But even those atoms are formed from smaller stuff. Atoms are made up of electrons, protons and neutrons. Electrons, protons, and neutrons are made up of quarks. We think quarks might be made up of strings.

Have you ever wondered how all the elements got put together? Well, I won’t tell the whole story (mostly because we don’t know it), but part of the answer is in the stars. Hydrogen (H) and helium (He) are the only two elements that are just floating around the universe on their own. Hydrogen: a proton and an electron (usually). Helium: 2 protons, 2 neutrons and 2 electrons (usually). All the other elements had to be made from these. The elements heavier than helium, up through iron (Li to Fe) were created in the fusion that occurs inside stars. The intense heat and pressure inside a star causes the atoms to bang into one another and fuse into heavier elements. All the elements heavier than iron need even more heat and pressure than the star can provide to form, and all of these elements were created inside supernovae, the explosive death of large stars.

All the elements heavier than H and He were created inside either the life or the death of a star, meaning that you and I are literally made of stardust. There’s some perspective for you.

Lightening can help determine a storm’s intensity

28 Sep

Scientists are getting better at predicting where and when storms will hit, thanks to satellites and radar installations. But they are not so good at predicting a storm’s intensity. They can tell when a storm will hit the gulf coast, but are unable to predict whether it will wreak havoc on the coast or die away when it hits the land. Earth Networks think they can do better.

These guys are a company of people who use electromagnetic sensors to monitor lightening within a storm, and that allows them to predict a storm’s intensity. Multiple sensors allows them to triangulate the location of each lightening event within the cloud. Supposedly the lightening is fiercest in the center of the cloud at the beginning of a storm’s life cycle, but the lightening shifts towards the outskirts of the storm as it loses intensity. The downside is that these monitors have to be in the storm’s path, so it would take a lot of installations to catch the storms as well as we’d like. But still there are some areas where it would be well worth it.

Earth Networks claims to have predicted a tornado with a 50 minute warning, instead of what the people of that area did receive, which was just a few minutes. That extra 40 minutes would make a world of difference. Pretty cool stuff.

Read more here.

The search for GWs (and I don’t mean $)

27 Sep

General relativity predicts that gravitational waves (GWs) exist. It as an extremely well-accepted notion that they do exist (relativity has done a pretty good job so far, despite recent doubts on the subject). We have not yet directly observed gravitational waves, but many people are trying to do so, including the people at the LIGO gravitational wave observatory.

Gravitational waves are small deformations of space. Bodies with mass accelerating create gravitational waves. Our earth is spewing them as we accelerate around our sun. Our speed is more or less constant (it isn’t really, but we don’t need to think about that now), but we are accelerating towards the sun as we travel in a circle instead of a straight line. It’s kind of like when you’re skiing and you turn quickly to snow spray someone. Astronomical events are the logical place  to look for gravitational waves. Two bodies with mass colliding violently, like two neutron stars for example, would create some pretty good gravitational waves. The truth is that even the largest gravitational waves are extremely small. If two neutron stars collided on the other side of our galaxy, a meter-long bar on earth would lengthen by 0.1am (attometer = 10-18m), which is quite a bit smaller than an atom. Needless to say, this is extremely difficult to detect.

A typical gravitational wave observatory is a beam of light split along two different paths and brought together again very precisely with a bunch of mirrors in a vacuum. Unfortunately, the thing we are trying to measure is so small that the vacuum (zero-point) fluctuations affect the measurements. Even if you have absolutely no outside photons in your vacuum chamber, you will still get electromagnetic noise from the vacuum itself. The ground state (or state of lowest energy) of the electromagnetic field in the chamber still has some energy. It is related to the uncertainty principle. It can also be described as photons jumping in and out of existence in the vacuum. Weird. Welcome to the world of quantum mechanics.

The people at LIGO have come up with a pretty clever way to increase the signal to noise ratio: squeeze the light. You can’t measure both amplitude (brightness of the light) and phase with absolute accuracy because of the effect. The better you can align the phase, the smaller the spacial deformation you can measure. In light waves, the noise is usually equally distributed between phase and amplitude. Squeezed light is light where the amplitude is very noisy (to satisfy the uncertainty principle), and the phase has noise way below the quantum limit. And if phase is what you’re interested in, that’s all the better for you. Keep in mind that the problem noise is from the vacuum fluctuations and not the light source you use, but for some reason involving quantum entanglement, having squeezed light in the chamber causes the vacuum fluctuations to be squeezed in the same way (I know, it blows my mind too). Squeezed light allows you to control the phase of your experiment better, which allows you to detect smaller spacial deformations, i.e. lower energy gravitational waves. We still may be a long way off from actually detecting a gravitational wave, but this is a big step in the right direction.

Read more here, and check out this movie of two neutron stars colliding and the resultant gravitational waves.

Biggest magnetic field ever

26 Sep

Here’s a fun one. German scientists have made a magnetic field of 91.4 T. That is BIG! The earth’s magnetic field is between 30 and 60 microTesla (says Wikipedia). That means it’s between 0.000030 and 0.000060 Tesla. The magnetic field they created is a millions times that of the earth’s magnetic field at the surface of the earth.

Honestly, it’s just a huge wrapping of copper coil inside another huge wrapping of copper coil… you get the idea. Flowing electrical current creates a magnetic field around itself, so line up a bunch of currents and you can create a magnet. The big one was tricky to engineer, though, because the windings would normally tear themselves apart at about 25 Tesla. Big magnets are good for researching superconductors, etc very accurately. Read more here.

Einstein ain’t gonna be happy about this

23 Sep

Nothing can travel faster than the speed of light, c. In fact, nothing with mass can even reach the speed of light. It is the “universal speed limit.” We’ve been saying it for decades. It is one of the main tenets of relativity, a theory which has had a lot of evidence to support it and has not yet been truly called into question. Well, the speed of light as a universal speed limit is being called into question now.

First of all, you need to know about neutrinos. Neutrinos are electrically neutral subatomic particles. They are weakly interacting, which means that they can go through matter without hitting or interacting with anything. In fact, a cascade of neutrinos is raining down on you right now from the cosmos, through the atmosphere, through buildings, through you. Neutrinos were first observed in 1970 at Argonne National Laboratory (See photo at right of the world’s first neutrino observation. A neutrino collides with a proton and creates the three particle paths shown: a proton [short path], a mu-mason [long path] and a pi-mason). We call neutrinos “massless” because they were originally thought to be so, but the truth is that they have been proven to have some mass (because they undergo flavor oscillations–yes, that’s a thing), though very little.

A group of scientists called the OPERA collaboration have taken measurements indicating faster-than-light travel of neutrinos. It has scientists all atwitter. I, for one, can’t stop thinking about the possible implications of such a result. Of course, we all need to take a deep breath because much is yet to be seen. The OPERA scientists themselves are, wisely, being extremely cautious. Particle physics experiments are extremely complicated. This experiment involves using a proton beam at CERN to create the neutrinos and sending them hundreds of miles to an underground detector at Gran Sasso Laboratory. There are many data-altering factors to account for. That isn’t to say that scientists are being in any way careless. They have certainly been very meticulous in their experiment, collaborated with many scientists, reproduced the results in several experiments over three years and used a very large statistical data set. These neutrinos are much higher energy than the ones we study from supernovae, which might explain why we haven’t encountered this phenomenon before… except that there was no energy dependence in their results. There is another team of scientists that claims to have produced greater-than-c velocity measurements for neutrinos, but that they didn’t take the results seriously because they seemed so improbable.

There are many doubts. But it is clear that the OPERA scientists have put a lot of thought and effort into discovering any glitch that could be affecting their results, which is the right thing to do in any experiment, much more so one with results as paradigm-shifting as these. The fact that they feel confident enough to announce it and put a paper out is enough to get everyone thinking. There will be much research done in the future to corroborate or dispute these findings. Only time and billions of dollars of research will tell.

If the findings turn out to be sound, the next step will be discovering theory to explain why neutrinos can travel faster than the speed of light. The only thing I can even think of is that the neutrinos somehow shortcut through extra-planar dimensions, which may not be as far-fetched as it sounds. Mother nature is pretty crazy sometimes.

Watch the webcast presenting the results.

Applied magnetic field enhances superconductivity

22 Sep

Metals conduct electricity better at low temperatures. Superconductivity is a phenomenon exhibited by some materials where the resistance of that material drops to zero, meaning that it conducts electricity very well, below a certain critical temperature. And I mean VERY well…like electrical current can run around forever in there. (Picture shows levitation of a magnet due to an induced magnetic field by the superconductor beneath).

Superconductivity is a very useful feature, but the problem is that the critical temperature is usually extremely low. It is a bit impractical to work with something that has to be kept at such a low temperature. There are high-temperature superconductors, but we are talking 90K (-300 degrees F),which is still pretty cold. Scientists have been looking for ways to increase the critical temperature of materials to make superconductivity more applicable.

For a minute, let’s look at the theory. There are a couple different ways of explaining the phenomenon of superconductivity. BCS theory describes it as a “condensation” of elections into bound, boson-like, states due to electron-phonon (quantum mechanical characterization of vibration) interaction. Which pretty much means that the electrons pair up because of the attractions and repulsions caused by lattice vibrations. You can kind of think of it classically in that the electron will pull the positive parts of the lattice towards itself, causing a net positive density around the first electron, which then attracts another electron. These are known as Cooper pairs–Cooper is the “C” in BCS.

According to BCS theory, applied magnetic fields should lower the superconductivity by disrupting these pairs of electrons. It would break up the symmetry. There have been some cases where an applied magnetic field slightly enhances the superconductivity, but never actually raises the critical temperature. It was thought that the magnetic field suppressed the negative effects of paramagnetic impurities in the material, causing the slight increase in superconductivity. This paper, however, shows that applied magnetic field can actually raise the critical temperature of the material, while the presence of impurities still decreases it, which completely flies in the face of accepted theory.