What happened before the big bang? You might ask what is north of the North Pole.
Second Generation
A new star has been discovered that was born from the very first stars of the universe. We can identify it by its particularly low metallicity.
Easing Tension With Neutrinos
a new paper published in Physical Review Letters gives a measure of neutrino mass, and it does so by alleviating the tension between cosmological parameters.
Go With the Flow
When measuring the motion of distant galaxies, we use the Doppler effect to measure their speed relative to us. Basically, as a galaxy moves away from us, the light from the galaxy appears more red than it actually is. This is similar to the way the sound of a train can sound lower as it moves away from you. Of …
Energy Matters
How do we know that dark energy isn’t due to some kind of repulsive matter? If we speculate on the effects of repulsive matter, we find that what we predict isn’t what we see. Whatever dark energy is, observational evidence shows it isn’t matter.
One Singular Sensation
A new paper shows that we can simulate magnetic monopoles in condensed matter. This research may give us a better understanding of hypothetical magnetic monopole particles that could solve one of the great mysteries of astrophysics.
I’m Tired…
Yesterday I wrote about the Alcock-Paczynski cosmological test (http://goo.gl/uouVEh), and how it narrowed the field of cosmological models down to two broad choices: an expanding universe with dark matter and dark energy, or a static universe that exhibits what is known as “tired light”. Now you might think that adding “tiredness” to light is no worse than inventing “dark matter” and “dark energy” to fit observational data. From a theoretical standpoint you’d be right. So why do astronomers accept dark matter and dark energy rather than tired light?
The Shape of Things
The most widely accepted model for the universe, sometimes called the standard model of cosmology, is known as the ΛCDM model. The Λ or “lambda” refers to the dark energy parameter known as the cosmological constant (which often uses lambda to represent its value). The CDM stands for Cold Dark Matter, which is the type of dark matter currently best supported by observation. In the ΛCDM model, the matter of the universe consists of regular matter (about 5%), cold dark matter (about 27%). Dark energy is then caused by a cosmological constant, which is a property of space and time itself, giving rise to dark energy.
A Kodak Moment
NASA has recently released the WMAP 9 year mission results. It’s taken the WMAP team two years to analyze this latest (and last planned) round of data. On the one hand, the results are just as we expect.