Dark matter has long been one of the most mysterious things in the cosmos. It was first proposed in the 1930s as an idea to address stellar motion in some galaxies. The first solid evidence of dark matter was gathered by Vera Rubin, who studied the rotational motion of galaxies. The motion of these galaxies didn’t add up unless they contained a large amount of unseen mass. There must be some exotic, invisible matter unlike anything known before.
If dark matter exists, then it must have two major properties. First, it cannot interact strongly with light, otherwise we would see it and it wouldn’t be “dark.” Second, it must interact with other matter gravitationally, to make visible matter move in strange ways. We know of several things that satisfy those conditions, such as neutrinos or tiny black holes, but these can’t be dark matter. We know this in part because we are now able to take its temperature.
Continue reading “The Debate Over Cold Dark Matter Warms Up As Astronomers Take Its Temperature”
In a recent post I wrote about a study that argued dark energy isn’t needed to explain the redshifts of distant supernovae. I also mentioned we shouldn’t rule out dark energy quite yet, because there are several independent measures of cosmic expansion that don’t require supernovae. Sure enough, a new study has measured cosmic expansion without all that mucking about with supernovae. The study confirms dark energy, but it also raises a few questions.
Continue reading “There’s a new method to measure the expansion rate of the Universe, but it doesn’t resolve the Crisis in Cosmology”
Stars are formed within large clouds of gas and dust known as stellar nurseries. While star formation was once seen as a simple gravitational process, we now know it is a complex dance of interactions. When one star forms it can send shock waves through the interstellar medium that trigger other stars to form. Supernovae and galactic collisions can trigger the creation of stars as well. One way to study stellar formation is to look at where stars form within a galaxy.
Continue reading “A Huge Wave is Passing Through the Milky Way Unleashing New Stellar Nurseries”
The universe is expanding. When we look in all directions, we see distant galaxies speeding away from us, their light redshifted due to cosmic expansion. This has been known since 1929 when Edwin Hubble calcuated the relation between a galaxy’s distance and its redshift. Then in the late 1990s, two studies of distant supernovae found that the expansion of the universe is accelerating. Something, some dark energy, must be driving cosmic expansion.
Continue reading “New Research Casts A Shadow On The Existence Of Dark Energy”
When two black holes merge, they release a tremendous amount of energy. When LIGO detected the first black hole merger in 2015, we found that three solar masses worth of energy was released as gravitational waves. But gravitational waves don’t interact strongly with matter. The effects of gravitational waves are so small that you’d need to be extremely close to a merger to feel them. So how can we possibly observe the gravitational waves of merging black holes across millions of light-years?
Continue reading “LIGO Will Squeeze Light To Overcome The Quantum Noise Of Empty Space”
The universe is governed by four fundamental forces: gravity, electromagnetism, and the strong and weak nuclear forces. These forces drive the motion and behavior of everything we see around us. At least that’s what we think. But over the past several years there’s been increasing evidence of a fifth fundamental force. New research hasn’t discovered this fifth force, but it does show that we still don’t fully understand these cosmic forces.
Continue reading “A Fifth Fundamental Force Could Really Exist, But We Haven’t Found It Yet”
Jupiter is the largest planet in the solar system. In terms of mass, Jupiter towers over the other planets. If you were to gather all the other planets together into a single mass, Jupiter would still be 2.5 times more massive. It is hard to understate just how huge Jupiter is. But as we’ve discovered thousands of exoplanets in recent decades, it raises an interesting question about how Jupiter compares. Put another way, just how large can a planet be? The answer is more subtle than you might think.
Continue reading “How Large Can A Planet Be?”
The universe is a seemingly endless sea filled with stars, galaxies, and nebulae. In it, we see patterns and constellations that have inspired stories throughout history. But there is one cosmic pattern we still don’t understand. A question that remains unanswered: What is the shape of the universe? We thought we knew, but new research suggests otherwise, and it could point to a crisis in cosmology.
Continue reading “New Research Suggests that the Universe is a Sphere and Not Flat After All”
The universe bathes in a sea of light, from the blue-white flickering of young stars to the deep red glow of hydrogen clouds. Beyond the colors seen by human eyes, there are flashes of x-rays and gamma rays, powerful bursts of radio, and the faint, ever-present glow of the cosmic microwave background. The cosmos is filled with colors seen and unseen, ancient and new. But of all these, there was one color that appeared before all the others, the first color of the universe.
Continue reading “What Was The First Color In The Universe?”
When a NASA engineer announces a new and revolutionary engine that could take us to the stars, it’s easy to get excited. But the demons are in the details, and when you look at the actual article things look far less promising.
Continue reading “NASA Engineer Has A Great Idea for a High-Speed Spacedrive. Too Bad it Violates the Laws of Physics”