News: Best ever map of the early universe revealed


Best ever map of the early universe revealed
New Scientist Friday March 17, 06:00 PM
http://uk.news.yahoo.com/17032006/12/best-map-early-universe-revealed.html

By Stephen Battersby

The universe went through a traumatic growth spurt before it was a
billionth of a billionth of a second old, according to the latest data
from the Wilkinson Microwave Anisotropy Probe (WMAP).

The probe has also given physicists their first clues about what drove
that frantic expansion, and revealed that the cosmic "dark age" before
the first stars switched on was twice as long as previously thought.

On Thursday, the WMAP team revealed the best map ever drawn of
microwaves from the early universe, showing variations in the
brightness of radiation from primordial matter. The pattern of these
variations fits the predictions of a physical theory called inflation,
which suggests that during the first split second of existence the
universe expanded incredibly fast.

The variations in the density of matter that the microwave map shows
up were created by quantum fluctuations during the expansion,
according to the theory. If so, then those fluctuations provided the
seeds for the gravitational growth of galaxies and stars - without
inflation the universe would still be a featureless cloud of gas.

Back in 2003, early WMAP data already seemed to fit the theory of
inflation, but there was one big question mark. Astronomers thought
that ionised gas created by the first generation of stars might be
mimicking the imprint of inflation by scattering the microwaves on
their way to us from distant parts of the universe.

Now the team say not. With three years of data instead of one, they
have been able to map not just the brightness but also the
polarisation of cosmic microwaves. The polarisation reveals just how
much the waves have been modified by bouncing off ionised gas. After
subtracting that effect from the temperature map, the team still find
that inflation fits the pattern.

It predicts that larger clumps in the background are brighter than
smaller clumps, just as the data show. Not everyone will be convinced,
but this is the strongest evidence so far in support of inflation.
"Galaxies are nothing but quantum mechanics writ large across the
sky," says theoretical physicist Brian Greene at Columbia University,
New York, US.

So what force could actually have caused inflation? There have been
hundreds of speculative physical models, postulating as yet unknown
energy fields. But the new data are precise enough to rule out many of
these ideas - especially some of the more complicated ones. "The
simplest of the models fits the data well," says WMAP team member
David Spergel at Princeton University, New Jersey, US.

That simple model should generate strong gravitational waves, which
would leave their own distinctive imprint on the polarisation of the
microwave background. If either WMAP or ESA's upcoming Planck
satellite can detect a gravitational-wave signal, physicists will
begin to learn why inflation happened, and that could have profound
implications for fundamental physics.

Meanwhile, a slightly more prosaic puzzle has been solved. The
original WMAP data suggested that the first stars started ionising gas
after only 200 million years, seemingly leaving too little time for
gas to gather into clumps and make stars. The new data show it did not
happen for 400 million years - a long age of darkness, and plenty of
time for the first stars to form.
--
Bob.

.

Relevant Pages

  • God in Super Cosmos?
    ... self-reproducing universe and the version of the Steady State hypothesis ... C-field playing the part of the scalar field that drives inflation. ... appeared out of nothing at all, and contains zero energy overall, was ... quantum fluctuation so small that it only contained one monopole. ...
    (sci.math)
  • God in Super Cosmos?
    ... self-reproducing universe and the version of the Steady State hypothesis ... C-field playing the part of the scalar field that drives inflation. ... appeared out of nothing at all, and contains zero energy overall, was ... quantum fluctuation so small that it only contained one monopole. ...
    (sci.physics)
  • God in Super Cosmos?
    ... self-reproducing universe and the version of the Steady State hypothesis ... C-field playing the part of the scalar field that drives inflation. ... appeared out of nothing at all, and contains zero energy overall, was ... quantum fluctuation so small that it only contained one monopole. ...
    (sci.astro)
  • why dark energy density is small
    ... Our early universe has low entropy compared to present universe. ... Sir Roger Penrose says this is a big problem for inflation theory - it's the Arrow of Time problem - why irreversible aging is in same sense as expansion of 3D space with dark energy speeding up of that cosmic expansion. ... this is precisely what we expect from the retro-causal world hologram in which 3D space at our moments of perception of our entire pocket universe on the landscape is simply a hologram image of the future 2D deSitter horizon. ... Because it has a very similar formal structure to the internal symmetry Yang-Mills quantum field operators. ...
    (sci.math)
  • why dark energy density is small
    ... Our early universe has low entropy compared to present universe. ... Sir Roger Penrose says this is a big problem for inflation theory - it's the Arrow of Time problem - why irreversible aging is in same sense as expansion of 3D space with dark energy speeding up of that cosmic expansion. ... this is precisely what we expect from the retro-causal world hologram in which 3D space at our moments of perception of our entire pocket universe on the landscape is simply a hologram image of the future 2D deSitter horizon. ... Because it has a very similar formal structure to the internal symmetry Yang-Mills quantum field operators. ...
    (sci.physics)