13.73 Billion years BCE

Science doesn’t have a lot to say about what happened before the Big Bang, but researchers have now developed microwave detectors that will let them take a look at the first trillionth of a trillionth of a trillionth of a second after that primordial cosmic event.

A collaboration between scientists at the National Institute of Standards and Technology (NIST), Princeton University, the University of Colorado at Boulder, and the University of Chicago has yielded super-sensitive microwave detectors that were revealed at the American Physical Society (APS) April meeting held in Denver during May.

Cosmic microwave temperature fluctuations fill the sky and are an echo of the first moment after the Big Bang (Credit: NASA/WMAP Science Team)

Cosmic microwave temperature fluctuations fill the sky and are an echo of the first moment after the Big Bang (Credit: NASA/WMAP Science Team)

The cosmic microwave background (CMB) is often referred to as the afterglow of creation. This remnant, or echo of the Big Bang fills the universe and various projects have obtained snapshots of the CMB stretching back closer and closer to the Big Bang. The new project will use a large array of the sensors mounted on a telescope mounted in the Chilean desert. They will look for subtle fingerprints of the CMB from primordial gravitational waves, ripples in the fabric of the spacetime continuum. Theory has it that these waves will have left an imprint on the direction of the CMB’s electric field, called the B-mode polarization.

This is one of the great measurement challenges facing the scientific community over the next twenty years, and one of the most exciting ones as well, says Kent Irwin, the NIST physicist leading the project.

Prototype NIST detector that will be used to spot signature of rapid inflation immediately after the Big Bang. (Credit: NIST)

Prototype NIST detector that will be used to spot signature of rapid inflation immediately after the Big Bang. (Credit: NIST)

If found, these waves would be the clearest evidence yet in support of the inflation theory, which suggests that all of the currently observable universe expanded rapidly (within the first tiny fraction of a second) from a subatomic volume, leaving in its wake the telltale cosmic background of gravitational waves.

The B-mode polarization is the most significant piece of evidence related to inflation that has yet to be observed, explained NIST’s Ki Won Yoon, at the APS meeting. A detection of primordial gravitational waves through CMB polarization would go a long way toward putting the inflation theory on firm ground.

These types of experiments can only be done by treating the universe as a whole as a cosmic laboratory. The particles and electromagnetic fields that exist immediately after the Big Bang are billions of times more energetic than those available even with the most powerful particle colliders on Earth today. On this energy scale, three of the fundamental forces of nature but excluding gravity, are predicted to merge into a single unified force.

At the energy scale at which inflation occurred, which is the GUT or Grand Unified Theory energy scale, only 3 out of the 4 fundamental forces are predicted to merge into a single unified force – electromagnetism, the strong nuclear force, and the weak nuclear force, Irwin told Spotlight.

The final force of nature, gravity, is not predicted to merge with the other three until a much higher energy scale referred to as the Planck scale, which would have occurred before inflation, and would not have been related to the primordial gravity waves. A theory that correctly incorporates gravity into a unified field is humorously referred to as a TOE or Theory of Everything, he adds.

Further reading

APS April 2009 Meeting
http://www.aps.org/meetings/april/

National Institute of Standards and Technology homepage
http://www.nist.gov/index.html

Suggested searches

Big Bang
cosmology
cosmic microwave background

The dark energy illusion

What if Copernicus were wrong and the earth actually has a special place in the universe? Not some metaphysical, philosophical, supernatural special place, but just special in that the local environment is not the same as other local environments across the reaches of space? If that were so, then measurements on the apparent acceleration of ancient supernovae at the fringes of the known universe could be null and void. And, if those supernovae are not accelerating away from us, then there is no need to invoke the mysterious, invisible force known as dark energy.

In the late 1990s, there was a universal change in cosmology. The mathematics that described the origins of the universe in the Big Bang suddenly did not add up. Astronomers had noticed that the remnants of ancient stars that exploded billions of years ago, Type Ia supernovae, seemed to be moving away from us faster and faster.

Could the mysterious force thought to be accelerating the expansion of the universe be an illusion caused by our humility? (Credit: Image courtesy of NASA/STScI/Ann Feild)

Could the mysterious force thought to be accelerating the expansion of the universe be an illusion caused by our humility? (Credit: Image courtesy of NASA/STScI/Ann Feild)

These observations were not anticipated by Big Bang theory, if anything the universe should ultimately slow down and perhaps collapse back on itself. The evidence of these supernovae suggests that a force, dubbed dark energy, is resisting gravity and causing the aftermath of the Big Bang to accelerate.

Dark energy is thought to pervade the whole universe, a phenomenon as mysterious as the dark matter that also lies hidden across space. As with dark matter, scientists have no idea what it is or from where it originates. What they do know is that when they do their cosmic sums, dark energy accounts for 73% of the universe’s total energy, dark matter 23%, and the galaxies, stars, cosmic dust and all the planets representing just about 4%.

But a new study undertaken by physicists at Oxford University offers to shift the balance once more. Timothy Clifton, Pedro Ferreira, and Kate Land have suggested that rather than our physical position in the universe being irrelevant to the overall scheme of things, the Earth actually sits in a location of particularly low density. This, they explain, would distort our basic measurements of other regions of the universe, including observations of ancient supernovae.

The researchers explain that it should be possible to use measurements of the local red shift – the astronomical Doppler shift that stretches the wavelength of light from the stars as the universe expands – of objects and how this relates to their brightness and distance to show that in conflict with the Copernican principle, the Earth actually is in a physically, as opposed to metaphysically, special region of the Universe.

They suggest that the ongoing and future planned surveys of type Ia supernovae could focus on a particular red shift range (about 0.1–0.4), which will be ideally suited to determining whether their idea holds true over new distances without having to invoke dark energy to explain them.

Further reading

Phys. Rev. Lett., 101, 131302 (2008)
http://dx.doi.org/10.1103/PhysRevLett.101.131302

Dr Timothy Clifton homepage
http://www.jesus.ox.ac.uk/staff/clifton.php

Sciencebase, 6, 10, 2008
https://www.sciencebase.com/science-blog/cosmic-effort-sheds-light-on-dark-energy.html

Suggested searches

cosmology
Big Bang
supernovae
dark energy
redshift

The dark side of matter revealed

There really is dark matter out there, says Dennis Zaritsky of the University of Arizona talking of the first evidence for this elusive cosmological substance, Now we just need to figure out what it is.

It was side-on views of two merging galaxy clusters made with state-of-the-art optical and X-ray telescopes that allowed Zaritsky and his colleagues to make this startling discovery. Dark matter is matter that does not emit or reflect enough electromagnetic radiation to be observed directly. Astronomers have assumed since the 1930s that most of the Universe must be composed of dark matter because of the way galaxies move through space. Our present understanding of gravity implies that the Universe must contain five times as much dark matter as normal matter

Zaritsky and colleagues have found evidence of dark matter

Zaritsky and colleagues have found evidence of dark matter

Evidence for dark matter has not been forthcoming. However, our theories of cosmology and the ultimate fate of the Universe hinge on whether or not it is real or not. The only means astronomers have of testing whether dark matter exists is to infer it from the gravitational effects it has on the more familiar visible matter.

When galaxy clusters merge, the galaxies themselves are so sparsely scattered in space that they don’t collide, team leader Doug Clowe, now at Ohio University explains, Even if two galaxies do pass through each other, the distance between the stars is so great that even stars won’t collide. Galaxies basically plough through each other almost without slowing down.

The galactic bullet cluster formed as two large galactic clusters merged in the most energetic known event since the Big Bang (Credit: NASA)

The galactic bullet cluster formed as two large galactic clusters merged in the most energetic known event since the Big Bang (Credit: NASA)

Most of a galaxy cluster’s normal mass lies in its diffuse hot gas. Galaxy clusters typically contain ten times as much ordinary mass in gas as in stars. So when galaxy clusters merge, the hot gas from each cluster drags on the other, slowing all the gas down. This means that while the galaxies continue to speed through space much of the gas is left behind.

Observations made with NASA’s Chandra X-ray Observatory showed the bulk of ordinary matter is in the hot gas clouds left in the wake of the galaxies. Part of this million-degree plasma of hydrogen and helium, the part from the smaller cluster, forms a spectacular bullet-shaped cloud because a bow shock, or supersonic shock wave, is created in the collision.

When the astronomers mapped the region of the sky around the galaxies in optical light, they discovered far more mass near the galaxies, ahead of the gas cloud. They analyzed gravitational lensing of distant galaxies in images taken with NASA’s Hubble Space Telescope, the European Southern Observatory’s 2-metre Wide-Field Imager and one of the twin 6.5-metre Magellan telescopes that a consortium that includes UA operates in Chile. They discovered the mass of non-luminous, or dark, matter that causes the lensing is far greater than the mass of ordinary matter in the gas cloud.

Nature gave us this fantastic opportunity to see hypothesized dark matter separated from ordinary matter in this merging system, explains Clowe, Prior to this observation, all of our cosmological models were based on an assumption that we couldn’t prove: that gravity behaves the same way on the cosmic scale as on Earth.

Astronomers have been in the somewhat embarrassing position of saying that we understand the Universe, although more than 80 percent of it is something we don’t know anything about, adds Zaritsky. That has all changed thanks to this discovery.

Further reading

Astrophys J Lett, in press
http://arxiv.org/abs/astro-ph/0608407

Dennis Zaritsky
http://ngala.as.arizona.edu/dennis/

Chandra X-ray Observatory
http://www.nasa.gov/mission_pages/chandra/main/

Suggested searches

dark matter