Saturday, December 13, 2008

Why do galaxies spiral? - the wisdom from the frying pan!


While reading the New Scientist article on how water droplets behave like black holes under certain induced conditions, I am reminded of the 'phenomena' of formation of spiral galaxy (!) in my frying pan while cleaning it with dish-washing liquid.

One can try this out. When you are rubbing the curved pan with the scrubber and washing liquid and the lather is formed, move to the fringes of the pan. When you are rubbing the edges of the pan in quick movement, you can see a beautiful replica of spiral galaxy of the lather  covering the pan. The spiraling is created by agitation or circular movement on the outer edge.

I used to wonder whether this is the principle on which the galaxies go spiral.

According Hindu wisdom (as told by Bheeshma in Mahabahratha and Arya bhatta in Arya bhatteyam) there are two types of currents in the cosmos comprising of totally 7 currents. They are Parivaha and Paraavaha.

While former type is operating in the earth with 5 currents, the other is operating in outer space with  two distinct currents. Of these two currents of Parivaha, one moves the stars and galactic material in Pitru-yana and the other (Paraavaha) moves them in Deva-yana. The former leads to cycling and re-cycling whereas the latter leads the materials to locales from which they can not get into recycling.

From the description in Hindu thought it is known  that the galactic materials are borne by some force which they call as Parivaha vaayu ..

This vaayu moves, so also the galaxies move.

If the Vaayu moves in the outer edges of the galaxy which it holds, wont there be a phenomenon of the galaxy moving in a spiral way?

This can happen only if the space in which the galaxy is placed is curved.

My guess is that Space is somewhat curved like a trough and the galactic materials are moving in a medium called Parivaha vaayu. This Vaayu rotates the material at their outer edge so that the process of movement of the entire galaxy happens in a spiral way.

This (Parivaha) may be absent in the case of non-spiral galaxy. The other type of current (Paraavaha) of the Deva yana course may be around them and  holding them

The future of those galaxies may be such that they escape re-cycling.

It may throw interesting information  if we follow the non-spiral galaxies too,  their formation and further course.

* Another article from New Scientist is also given below on the new scientific thought of 'bouncing universe' which does not necessarily spring from a singularity of a Big Bang type and end up in another singularity. Our Hindu wisdom also is that it is a continuing universe with changes in state of matter and not from point to point singularity. This Hindu wisdom was earlier discussed in this blog in




Why water droplets can be like black holes


WHAT does a drop of water have in common with a black hole and an atom? Well, levitating water droplets can now simulate the dynamics of both cosmological and subatomic objects.

Richard Hill and Laurence Eaves at the University of Nottingham, UK, turned to water droplets because the surface tension that holds the drops together can be used to model other forces. For example, the event horizon of a black hole is sometimes thought of as a "stretched" membrane with a surface tension. Similar forces also prevent atoms from flying apart.

The team levitated the droplets using an effect called diamagnetism: when an external magnetic field was applied to the droplets, they created their own opposing magnetic field, initiating a repulsive force strong enough to counteract gravity. To set the droplets spinning, they implanted two tiny electrodes, which generated an electric field.

They found that once a droplet with a diameter of 1 centimetre reached about 3 revolutions per second, its shape, when viewed from above, became triangular, an effect never seen before in the lab (Physical Review Letters, DOI: 10.1103/PhysRevLett.101.234501).

"The breakthrough in this work is the ability to reproduce, in a simple table-top experiment, 100 years of theoretical work in fluid dynamics," says Vitor Cardoso of the University of Mississippi.


Did our cosmos exist before the big bang?


Continue reading page |1 |2 |3
ABHAY ASHTEKAR remembers his reaction the first time he saw the universe bounce. "I was taken aback," he says. He was watching a simulation of the universe rewind towards the big bang. Mostly the universe behaved as expected, becoming smaller and denser as the galaxies converged. But then, instead of reaching the big bang "singularity", the universe bounced and started expanding again. What on earth was happening?
Ashtekar wanted to be sure of what he was seeing, so he asked his colleagues to sit on the result for six months before publishing it in 2006. And no wonder. The theory that the recycled universe was based on, called loop quantum cosmology (LQC), had managed to illuminate the very birth of the universe - something even Einstein's general theory of relativity fails to do.
Einstein's relativity fails to explain the very birth of the universe
LQC has been tantalising physicists since 2003 with the idea that our universe could conceivably have emerged from the collapse of a previous universe. Now the theory is poised to make predictions we can actually test. If they are verified, the big bang will give way to a big bounce and we will finally know the quantum structure of space-time. Instead of a universe that emerged from a point of infinite density, we will have one that recycles, possibly through an eternal series of expansions and contractions, with no beginning and no end.
LQC is in fact the first tangible application of another theory called loop quantum gravity, which cunningly combines Einstein's theory of gravity with quantum mechanics. We need theories like this to work out what happens when microscopic volumes experience an extreme gravitational force, as happened near the big bang, for example. In the mid 1980s, Ashtekar rewrote the equations of general relativity in a quantum-mechanical framework. Together with theoretical physicists Lee Smolin and Carlo Rovelli, Ashtekar later used this framework to show that the fabric of space-time is woven from loops of gravitational field lines. Zoom out far enough and space appears smooth and unbroken, but a closer look reveals that space comes in indivisible chunks, or quanta, 10-35 square metres in size.
In 2000, Martin Bojowald, then a postdoc with Ashtekar at the Pennsylvania State University in University Park, used loop quantum gravity to create a simple model of the universe. LQC was born.
Bojowald's major realisation was that unlike general relativity, the physics of LQC did not break down at the big bang. Cosmologists dread the singularity because at this point gravity becomes infinite, along with the temperature and density of the universe. As its equations cannot cope with such infinities, general relativity fails to describe what happens at the big bang. Bojowald's work showed how to avoid the hated singularity, albeit mathematically. "I was very impressed by it," says Ashtekar, "and still am."
Jerzy Lewandowski of the University of Warsaw in Poland, along with Bojowald, Ashtekar and two more of his postdocs, Parampreet Singh and Tomasz Pawlowski, went on to improve on the idea. Singh and Pawlowski developed computer simulations of the universe according to LQC, and that's when they saw the universe bounce. When they ran time backwards, instead of becoming infinitely dense at the big bang, the universe stopped collapsing and reversed direction. The big bang singularity had truly disappeared (Physical Review Letters, vol 96, p 141301).
But the celebration was short-lived. When the team used LQC to look at the behaviour of our universe long after expansion began, they were in for a shock - it started to collapse, challenging everything we know about the cosmos. "This was a complete departure from general relativity," says Singh, who is now at the Perimeter Institute for Theoretical Physics in Waterloo, Canada. "It was blatantly wrong."
Ashtekar took it hard. "I was pretty depressed," he says. "It didn't bode well for LQC." However, after more feverish mathematics, Ashtekar, Singh and Pawlowski solved the problem. Early versions of the theory described the evolution of the universe in terms of quanta of area, but a closer look revealed a subtle error. Ashtekar, Singh and Pawlowski corrected this and found that the calculations now involved tiny volumes of space.
It made a crucial difference. Now the universe according to LQC agreed brilliantly with general relativity when expansion was well advanced, while still eliminating the singularity at the big bang. Rovelli, based at the University of the Mediterranean in Marseille, France, was impressed. "This was a very big deal," he says. "Everyone had hoped that once we learned to treat the quantum universe correctly, the big bang singularity would disappear. But it had never happened before."
Physicist Claus Kiefer at the University of Cologne in Germany, who has written extensively about the subject, agrees. "It is really a new perspective on how we can view the early universe," he says. "Now, you have a theory that can give you a natural explanation for a singularity-free universe." He adds that while competing theories of quantum gravity, such as string theory, have their own insights to offer cosmology, none of these theories has fully embraced quantum mechanics.

To continue reading the article, click


வடுவூர் குமார் said...

உங்கள் பதிவுகள் தமிழில் இருந்தால் இன்னும் நன்றாக புரிந்துகொள்ளலாம்.
If these posts were in Tamil it may be easier for me to understand.

Jayasree Saranathan said...

I will do, sir.
Thank you.