Dark Matter is Serious Business

We've heard for quite a while now that there is a lot more dark matter out there than visible matter. One estimate is that dark matter constitutes five sixths of the total matter content of the universe.

A recent Hubble mapping of dark matter is confirming the observation that the distribution of galaxies (visible matter) follows the distribution of dark matter.

What really got my attention is a comment by Professor Carlos Frenk, from the University of Durham, UK: "In the next decade, I think most studies of the Universe's large-scale structure will be dark matter structure studies. In this sense, I think galaxies will be relegated to a secondary role."

Wow!

His theory is a leading model to explain how structures in the Universe evolved over cosmic time: Soon after the Big Bang, cold dark matter formed the first large structures in the Universe, which then collapsed under their own weight to form vast halos. The gravitational pull of these halos sucked in ordinary matter, providing a focus for the formation of galaxies.


Hubble's map: Dark matter may be invisible but it accounts for most of the Universe's mass. Its gravitational attraction acts as a template, pulling normal matter - the stars in their galaxy groupings – into the large-scale structures we can see through telescopes.

A new twist on the old placebo effect

Placebo Effect refers to the phenemenon where someone taking a dummy pill feels better. This is traditionally put down to "positive thinking", and this explanation has been supported by some scientific evidence too.

In one study, a bunch of about 1000 older people were profiled (using a questionnaire) and then surveyed again a decade later. It was found that those who had described themsleves as optimists had 55% lower risk of death from all causes, and 23% less risk of death from heart disease. The thinking is that pessimistic people probably are more prone to developing habits or problems that cut short their lives - like smoking, obesity and hypertension.

In another set of studies, scientists could find some physical manifestations of the placebo effect, rather than the traditional psychological explanation. For example, they could observe that the brain was releasing more endorphins (natural pain killers) when the patient had an expectation that the treatment he was getting would be effective, for instance, on being told that he was being given a pain reliever, while it was actually a dummy. More interestingly, another study found that the medication was less effective when the patient didn't know he was getting it. A computerized morphine administration system worked better when a nurse pretended to administer it.

However, the latest twist, is that the placebo effect is a classic case of correlation, not causation: people who take the placebos regularly tend to take better care of themselves in the first place. Those who don't take their meds (or placebos) regularly, probably have attributes (like depression) that make them less healthy.

Healing may lie not in the treatment but rather in patients’ emotional and cognitive processes of “feeling cared for” and “caring for oneself”, concludes one researcher.

Mysterious Mammatus Clouds

Mammatus Clouds form in turbulent air on the undersides of thunderstorms.


Photo credit: Matus Kocka of Brno, the Czech Republic from SpaceWeather.Com

Although mammatus clouds are popularly thought to signal the approach of severe weather, new research shows the opposite is true. These lumpy clouds are most often seen when storms are breaking up.


Photo: Also from SpaceWeather.Com

Taylor Column

When moving fluid comes into contact with a submerged object, it forks in two and flows around the object. But if the fluid is moving in a circle and rotating, something strange happens: the submerged object creates a "cylinder" of still water that extends from the top to the bottom of the fluid, well above the physical height of the object.

This "virtual" cylinder is known as a Taylor column and can disrupt the flow of water just as if it were a physical column.



credit: Semple/Moore/University of Toronto


This phenomenon in encountered in an amazing range of scenarious and scales, essentially whereever moving or rotating fluids are involved, for example in industrial processes, ocean currents, atmospheric phenomenon like winds, etc.

This phenemenon is named after the British physicist Geoffrey Ingram (G. I.) Taylor (1886–1975), who deviced experiments to study and provided mathematical explanations of this and many other hydrodynamics observations.

Taylor's experiment consisted of a rotating cylindrical tank of fluid. The tank is rotated at a high frequency. Once the fluid settles into solid-body rotation, a small cylinder (a fraction of the height of the fluid) is dragged along the bottom of the tank. Dye is then injected into the fluid. In a non-rotating tank, the dye is free to move anywhere in the fluid. However, in the rotating tank, the dye would be diverted from passing over the cylinder as if the cylinder's height were extended in a column from the top to the bottom of the fluid (see Figure 3) . This `imaginary' cylinder is known as a Taylor column.



When an object moves in a rotating flow, it drags along with it a column of fluid parallel to the rotation axis. This photograph shows the flow when a dyed drop of silicone fluid (radius 2 cm) rises through a large tank of water rotating at 56 rpm

Science may not be random, but I am

The "random" in the name of this blog describes my attitude to science. Despite my professed, and mostly true, scientific predisposition, I am not methodical in my approach to science.

I am not a scientist. I am not trained as one, and I don't make my living off it. I only have limited resources and time to spend on doing or learning science. However, I love science. I believe it's central to human civilization and survival. And I don't want to be disadvantaged in this respect. I want to keep abreast of the advances in science. This, I mostly do by reading articles off the internet and some books. This is neither a rigorous nor an effecient approach. But this is what works for me, for now, atleast.

As I go through this process of scientific discovery, although an indirect one, I have often wanted to keep a journal of it. I have wanted to share it with others. I don't know why I didn't think of blogging it earlier!