StartsWithABang writes: Sure, the Hubble Space Telescope gives us unparalleled views of our Universe. We can even use it – with its near-infrared camera, NICMOS – to view the very center of our galaxy, something completely blocked by dust in visible light. But part of the incredible power of Hubble relies not on anything to do with the spacecraft or the instruments itself, but rather on the fact that Hubble is only one part of NASA’s great observatories program. Combined with Spitzer (mid-and-far IR) and Chandra (X-ray) data, the astrophysics of this truly remarkable region is revealed in unprecedented detail.
StartsWithABang writes: The cosmic microwave background is a thing of beauty, as not only does its uniform, cold temperature reveal a hot, dense past that began with the hot Big Bang, but its fluctuations reveal a pattern of overdensities and underdensities in the very early stages of the Universe. It’s fluctuations just like these that give rise to the stars, galaxies, groups and clusters that exist today, as well as the voids in the vast cosmic web. But effects at the surface of last scattering are not the only ones that affect the CMB’s temperature; if we want to make sure we’ve got an accurate map of what the Universe was born with, we have to take everything into account, including the effects of matter as it gravitationally grows and shrinks. As we do exactly this, we find ourselves discovering the causes behind the biggest anomalies in the sky, and it turns out that the standard cosmological model can explain it all.
StartsWithABang writes: When you think of the Hubble Space Telescope, perhaps you think of what’s touted as its most major feat of all: peering off into deep, dark space, collecting light, and discovering the plethora of distant galaxies laying billions of light years beyond our own, like the Hubble deep field, ultra deep field or extreme deep field. But thanks to a combination of factors, including gravitational lensing, Hubble has beaten its own record, finding the most distant galaxies of all.
StartsWithABang writes: We thought — back in the time after Maxwell — that if we understood gravitation and electromagnetism, we’d understand all the forces in the Universe. But once we started to dive inside the atom, and once we discovered the atomic nucleus, a new puzzle arose. Every atom other than hydrogen has multiple protons (and neutrons) inside of it. Yet if the protons had a positive electric charge and the neutrons had no electric charge, the intense repulsion between like charges should drive all nuclei apart. But clearly that wasn’t what was happening in our Universe; something extra must be holding these nuclei together. That's what the strong force is, and this is how it works.
StartsWithABang writes: We’ve come an incredible distance in exploring the Universe. In the span of just a single human lifetime, we’ve gone from speculations about what other worlds in our Solar System might be like, the possibility of planets around other stars and wondering how many galaxies might be in our observable Universe to actual answers about all three of these profound questions. But as far as we’ve come, Earth is still the only planet we know of with life on it, and the only one even capable of habituating us as our home. An inspiring plea from those who've left Earth as to why we should take care of it.
StartsWithABang writes: When you look out at the nebulae in the night sky — especially if you’re seeing them with your eye through a telescope for the first time — you might be in for a big surprise. These faint, fuzzy, extended objects are far dimmer, sparser and more cloud-like than almost anyone expects. Yet thanks to some incredible image processing, assigning colors to different wavelengths and adjusting the contrast, we can make out detailed structures beyond what even your aided eye could ever hope to perceive. Here's how the magic happens, and what it teaches us.
StartsWithABang writes: The overwhelming scientific conclusion based on the observable evidence is that the Universe is expanding and cooling, having emerged from a hot, dense state in the past. We can extrapolate back to a time before neutral atoms existed, before even nuclei could form, and if we continue the extrapolation all the way back, we arrive at a singularity. Only, that last step isn't necessarily one we can take, and the insistence of many on its existence may be the biggest mistake ever made about the Big Bang.
StartsWithABang writes: The Universe is filled with a wide variety of stars, planets, galaxies and other optical phenomenon. Despite the fact that there are no such things as green stars, on rare occasions, galaxies themselves appear to be emitting isolated green wisps into intergalactic space. Since the first such object was discovered eight years ago, this was a hotly debated mystery, one that’s been solved with an unlikely phenomenon: the atomic transitions of ionized oxygen, or the same physics that underlies the aurorae here on Earth!
StartsWithABang writes: You’re used to real numbers: that is, numbers that can be expressed as a decimal, even if it’s an arbitrarily long, non-repeating decimal. There are also complex numbers, which are numbers that have a real part and also an imaginary part. The imaginary part is just like the real part, but is also multiplied by i, or the square root of -1. It's a simple definition: the Mandelbrot set consists of every possible complex number, n, where the sequence n, n^2 + n, (n^2 + n)^2 + n, etc.—where each new term is the prior term, squared, plus n—does not go to either positive or negative infinity. The scale of zoom visualizations now goes well past the limits of the observable Universe, with no signs of loss of complexity at all.
StartsWithABang writes: Before there were planets, galaxies, or even stars in the Universe, there really was light. We see that light, left over today, in the form of the Cosmic Microwave Background, or the remnant glow from the Big Bang. But these photons outnumber the matter in our Universe by more than a-billion-to-one, and are the most numerous thing around. So where did they first come from? Science has the answer.
StartsWithABang writes: It’s pretty obvious that the Universe exists in such a way that it admits the possibility of intelligent life arising. After all, we’re here, we’re intelligent life, and we’re in this Universe. So at minimum, the Universe must exist in such a way that it’s physically possible for us to have arisen. But are there physically interesting things we can learn about the Universe from this line of reasoning alone? As it turns out, the answer is yes, but the things we can learn are extremely limited both in terms of scientific and philosophical significance.
StartsWithABang writes: If you take two clusters, groups, or individual galaxies and collide them together, you'd expect the stars to pass through unperturbed, the gas to experience friction, slowing down and heating up, while the dark matter, if it's truly collisionless, will do the same thing as the stars. But if there's a tiny frictional force at work on dark matter, it, too, will slow down a little bit. A team looking at 72 groups and clusters saw no effect of slowing down, but then on the 73rd one, they saw a separation between the mass reconstruction and the stars. Is this the first sign of dark matter's interactions, or is it simply an astrophysical effect, or maybe even a fluke? A good recap and rundown of what we're looking at to the best of our knowledge.
StartsWithABang writes: When it comes to measuring the expansion history of the Universe, the concept is simple enough: take something you know about an object, like a mass, a size, or a brightness, then measure what the mass, size or brightness appears to be, and suddenly, you know how far away that object has to be. Add in a measurement of the object’s redshift, and you can figure out not only what the expansion rate of the Universe is today, you can figure out the entire expansion history, and therefore what makes the Universe up. For practically all of the 20th century, we used brightness — or standard candles — exclusively. But new developments in both galactic surveys (like SDSS) and our understanding of dark matter and inflation has enabled us to use a new technique: baryon acoustic oscillations, or a standard ruler, which now gives us the best constraints ever on what dark energy is.
StartsWithABang writes: You've heard the saying, "God does not play dice with the Universe," and quite likely, of Schrödinger's cat as well. The idea that the Universe is random and — in many ways — unpredictable and indeterministic, is unsettling, to say the least. Yet it seems to be a fact inherent to our quantum Universe, a fact that neither Einstein nor Schrödinger could ever accept. Paul Halpern dives in deep to these issues in his newest book, as astrophysicist Ethan Siegel dishes in his review.
StartsWithABang writes: Of course the closest galaxies to us are going to be the brightest, with Andromeda, the Magellanic Clouds and the Triangulum Galaxy all visible to the naked eye. But beyond our local group? The next brightest galaxy is an oddity: 29 million light-years away, half the diameter of our Milky Way, and containing properties of both spiral and elliptical galaxies. In unparalleled views, come take a look at the sombrero galaxy, and learn what makes it so phenomenal.