Liquid Universe

The Universe consisted of a perfect liquid in its first moments, according to results from an atom-smashing experiment.

Scientists at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory on Long Island, New York, have spent five years searching for the quark-gluon plasma that is thought to have filled our Universe in the first microseconds of its existence. Most of them are now convinced they have found it. But, strangely, it seems to be a liquid rather than the expected hot gas.

Quarks are the building blocks of protons and neutrons, and gluons carry the strong force that binds them together. It is thought that these particles took some moments to condense into ordinary matter after the intense heat of the Big Bang.

To recreate this soup of unbound particles, the RHIC accelerates charged gold atoms close to the speed of light before smashing them together. Previous experiments have shown that these collisions create something the size of an atomic nucleus that reaches 2 trillion degrees Celsius, about 150,000 times hotter than the centre of the Sun.

Now experiments have revealed that this hot blob is a liquid, which lives for just 10-23 seconds.

The surprising thing is that the interaction between the quarks and gluons is much stronger than people expected. The strength of this binding keeps the mixture liquefied despite its incredible temperature. It's as much a fluid as water in a glass.

The researchers worked out the liquid's structure by tracking the particles that spray out as the droplet falls apart and quarks team up to form normal matter. It's a very complicated thing says But it has been amazing at how simple the results are.

The resulting liquid is almost 'perfect': it has a very low viscosity and is so uniform that it looks the same from any angle.

This may help to explain why the deepest parts of the Universe seem similar wherever astronomers look. If the primordial liquid had been as viscous as honey, the Universe could have turned out much more lumpy. It is certain this will change our picture of the early Universe.

The researchers now hope to measure the heat capacity, viscosity and even the speed of sound in the quark liquid. Further investigations will inevitably take years to complete.

Magnetic Fields that guide you on a trip thro' time?

"My exercise every morning is to try and pour cold water on my fantasies." Don't worry, Massimo Giovannini is not thinking of anything salacious. He's a physicst at the CERN particle physics lab in Geneva, Switzerland, and Giovannini's flights of fancy concern the gigantic and mysterious magnetic fields that strech thro' space.

Govannini has good resons to fantasise: these cosmic magnetic fields, sometimes big enough to strech across cluster of galaxies, are one of the last unexplorered features of the universe, and could hone our theories about how the universe came into its present state. That's beacuse it is a possibility that todays fields are the legacy of those created mere instants after the big bang. The information contained in them could tell us how the universe developed into the vast cosmos which we can see and feel around us. "Primordial magnetic fields could influence the whole history of the universe," says Govinnini.

Our best bet to study these magnetic fields is the cosmic microwave background(CMB), the fossil radiation of the big bang. Cosmic magnetic fields- if we can get to grip with them- could offer a new, independent and extremely valuable source of cosmological data.

No one knows how the first significant magnetic fields arouse. Any charged particle racing across the universe will create its own tiny magnetic field, but is absoluetly not clear as to how we have magnetic fields that strech across galaxies as of today.

The Italian physict Enrico Fermi was the first to suggest that magnetic fields are littered in many places in galactic scale. But no one was ready to take his idea, even though people began to know that magnetic field were present for plants, stars and even the milky way centre. This attitude began to soften in the late 1970's when, using the 100-metre Effelsburg radio telescope near Bonn, Germany, Rainer Beck and his colleague ssaw something mysterious. They were studying "synchrotron" emissions from galaxies- radio waves emitted by charged particles spiralling around magnetic field lines. The emissions were polarised: that is. the plane of vibration of the electromagnetic wave was ordered- only not in the way expected by his team.

The amount of polarisation of these particle depends on the orientation and ordering of the magnetic field lines: if they are neatly ordered there will be more polarisation. If the magnetic field lines are small and randomly oriented then polarisation will be less. Since no one believed that galaxies contained ordered magnetic fields, ever one expected the latter. But to their suprise and astronishment they found the latter case! The degree of polarisation was quite high.

Things have changed dramatically from that time onwards. Contrary to everyone once thought, magnetic fields that strech across galaxies have become a comman place observation. Fields of about 10 pow-30 tesla are routinely measured in galaxies like our own Andromeda.
Supernovae and black holes produce minute fields of around 10 pow-22 tesla. The rotational effect of the galaxies can turn these small fields into large ones. A similar dynamo effect caused by the rotation of the earth probably explains the orgin and continuing existance of terrestrial magnetic field.

The main problem is that it should take several billion of years to build up fields of this strength but many galaxies are much younger than that. That leaves a another plausible explanation: that the fields were created in the the infant universe.

The exitment is not misplaced. Primordial magnetic fields - that is, those that formed during the first 3,00,000 years of the universe existance - would have left clues about the nature of the infant universe frozen into the fields that span the cosmos today. What's more, they might have affected the fundamental shape of the universe. If we find any evidence of this, it will fundamentally affect our understanding of the evoultion of the universe.

The first step towards understanding the magnetic universe (as i shall call it!) is to pin down the cause that would have generated the primordial magnetic fields. Among the best candidates is the phase trasition, the times when the properties of of a rapidly cooling universe changed dramatically from one instant to another. Could the events in this time period be the cause?

One thing that might have made these fields possible is the creation of shock waves. This would turn the random movement of protons and electrons, into flow of particles capable of creating a significant magnetic fields. We will have the answer within a couple of years: when the Large Hadron Collider starts up in 2007 at CERN, Geneva, Switzerland. But another possibility arised. Could the fluctuations in the electromagnetic fields during inflation have given raise to primordial magnetic fields?

Larry Widrow and Michel Turner from Queen's University,Kingston and University of Chicago proposed the above idea first, They found that to produce fluctuations in the electomagnetic fields produced during inflation , they had to tinker with the famous eqution formulated by James Clark Maxwell that described the behaviour of electric and magnetic fields. When the idea was first proposed, it didn't go well with the physicists, who didnt like to mess with the Maxwell's equations which are considered to be the Sacred cow of electromagnetic theory.

"At the movement, the most crucial thing on the agenda is to understand if these fields are primordial or not," says Giovannini. If they are, his fantasising would not be in vain.