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Astronomers have to be extra clever to map out the invisible dark matter in the universe. Recently, a team of researchers have improved an existing technique, making it up to ten times better at seeing in the dark.

Dark matter is frustratingly difficult to measure. It’s completely invisible: it simply doesn’t interact with light (or normal matter) in any way, shape, or form. But we know that dark matter exists because of its gravitational influence on everything around it – including the normal matter that makes up stars and galaxies.

As an example of this, take a look at gravitational lensing. A massive object, whether made of dark or normal matter, will bend the path of any light that passes close by. It’s usually an incredibly tiny effect, but definitely measurable. We can see lensing of starlight around the sun, for example, which is how we knew that Einstein’s theory of general relativity must be correct.

Distant light from the big bang is twisted as it travels to us. This could mean dark matter is more exotic than we thought.

The oldest light in the universe is that of the cosmic microwave background (CMB). This remnant glow from the big bang has traveled for more than 13 billion years. Along the way, it has picked up a few tales about the history and evolution of the cosmos. We just need to listen to what it has to say.

One of the ways the CMB tells a story is through its polarization. If you think of light as an oscillating wave, then this wave motion can have different orientations, the orientation of a light wave’s oscillation is known as its polarization. Often, light is a random jumble of orientations, making it unpolarized, but the light from the CMB is light that has scattered off the hot gas of the early universe and has an orientation known as E-mode polarization.

Continue reading “Polarized light from the cosmic background hints at new physics” »

For first time ever, Hubble observations reveal a massive galaxy actually in the latter stages of being stripped of its dark matter, say researchers.

Throughout all known space, between the stars and the galaxies, an extremely faint glow suffuses, a relic left over from the dawn of the Universe. This is the cosmic microwave background (CMB), the first light that could travel through the Universe when it cooled enough around 380,000 years after the Big Bang for ions and electrons to combine into atoms.

But now scientists have discovered something peculiar about the CMB. A new measurement technique has revealed hints of a twist in the light — something that could be a sign of a violation of parity symmetry, hinting at physics outside the Standard Model.

According to the Standard Model of physics, if we were to flip the Universe as though it were a mirror reflection of itself, the laws of physics should hold firm. Subatomic interactions should occur in exactly the same way in the mirror as they do in the real Universe. This is called parity symmetry.

The newly measured rate of a key nuclear fusion process that forged the first atomic nuclei matches the picture of the universe 380,000 years later.

Paging Philip Pullman.

O,.o circa 2011 antigravity? Antimatter gravity equals antigravity: D.

(PhysOrg.com) — In 1998, scientists discovered that the Universe is expanding at an accelerating rate. Currently, the most widely accepted explanation for this observation is the presence of an unidentified dark energy, although several other possibilities have been proposed. One of these alternatives is that some kind of repulsive gravity – or antigravity – is pushing the Universe apart. As a new study shows, general relativity predicts that the gravitational interaction between matter and antimatter is mutually repulsive, and could potentially explain the observed expansion of the Universe without the need for dark energy.

Ever since antimatter was discovered in 1932, scientists have been investigating whether its gravitational behavior is attractive – like normal matter – or repulsive. Although antimatter particles have the opposite electric charge as their associated matter particles, the masses of antimatter and matter particles are exactly equal. Most importantly, the masses are always positive. For this reason, most physicists think that the gravitational behavior of antimatter should always be attractive, as it is for matter. However, the question of whether the gravitational interaction between matter and antimatter is attractive or repulsive so far has no clear answer.

Continue reading “Antimatter gravity could explain Universe’s expansion” »

O,.o this reveals the hertz of the spacetime continuum: 3.

In the biggest events in the universe, massive black holes collide with a chirp and a ring. Physicists are finding ways to listen in.

An expert on massive stars, Massey has been studying our nearest grand spiral neighbor, the Andromeda Galaxy for decades now. Andromeda is a cornerstone of almost everything we now know about astronomy — from the first recognition that the cosmos is made up of individual galaxies to the discovery of the universe’s still unexplained dark matter. Please join us as we chat about this beautiful and beguiling galactic neighbor.