The Alan Sondheim Mail Archive

---------- Forwarded message ----------
Date: Mon, 30 May 2011 01:25:03
From: Portside Moderator <moderator@PORTSIDE.ORG>
Subject: New Method 'Confirms Dark Energy'

New Method 'Confirms Dark Energy'
By Paul Rincon
BBC News
19 May 2011

First results from a major astronomical survey using a
cutting-edge technique appear to have confirmed the
existence of mysterious dark energy.

Dark energy makes up some 74% of the Universe and its
existence would explain why the Universe appears to be
expanding at an accelerating rate.

The finding was based on studies of more than 200,000

Scientists used two separate kinds of observation to
provide an independent check on previous dark energy

Two papers by an international team of researchers have
been accepted for publication in the Monthly Notices of
the Royal Astronomical Society journal.

One type of observation used by the astronomers involves
measuring a pattern in how galaxies are distributed in
space. This pattern is known by the term "baryon
acoustic oscillations".

The second type of observation involves measuring how
quickly clusters of galaxies have formed over time. Both
of these techniques confirmed the existence of dark
energy and the acceleration in the expansion of the

The concept of dark energy was first invoked in the late
1990s by studying the brightness of distant supernovas -
exploding stars.

Einstein was right

To explain why the expansion of the Universe was
speeding up, astronomers had to either rewrite Albert
Einstein's theory of gravity or accept that the cosmos
was filled with a novel type of energy.

"The action of dark energy is as if you threw a ball up
in the air, and it kept speeding upward into the sky
faster and faster," said co-author Dr Chris Blake of the
Swinburne University of Technology in Melbourne,

"The results tell us that dark energy is a cosmological
constant, as Einstein proposed. If gravity were the
culprit, then we wouldn't be seeing these constant
effects of dark energy throughout time."

The Anglo-Australian telescope was used in the galaxy

The latest findings have come from a galaxy survey
project called WiggleZ, which began in 2006 and finished
this year. WiggleZ used data from Nasa's Galaxy
Evolution Explorer (Galex) space telescope and the
Anglo-Australian Telescope on Siding Spring Mountain in

The survey mapped the distribution of galaxies in an
unprecedented volume of the Universe, looking eight
billion years back in time - more than half the age of
the Universe.

Cosmologist Bob Nicholl, who was not involved with the
research, told BBC News: "This is a major step forward.
These guys are serious, major scientists and we've been
waiting for this result for some time.

The professor of astrophysics at Portsmouth University,
UK, added: "It's re-confirmation of dark energy, it
gives us another data point to fit our theories around
and it shows us the way to the future. More astronomers
are going to be doing this in years to come."

While dark energy makes up about 74% of the Universe,
dark matter - which does not reflect or emit detectable
light - accounts for 22%. Ordinary matter - gas, stars,
planets and galaxies - makes up just 4% of the cosmos.

However, despite scientists being able to infer the
existence of dark energy and dark matter, these
phenomena still elude a full explanation.


Portside aims to provide material of interest to people
on the left that will help them to interpret the world
and to change it.

Submit via email:

Submit via the Web:

Frequently asked questions:


Search Portside archives:

Contribute to Portside:

Generated by Mnemosyne 0.12.