72722353
submission
StartsWithABang writes:
A little over 300 years ago, a supernova — a dying, ultramassive star — exploded, giving rise to such a luminous explosion that it might have shone as bright as our entire galaxy. And nobody on Earth saw it. Located in the plane of our Milky Way galaxy, the light was obscured, but thanks to a suite of great, space-based observatories (Hubble, Spitzer, and Chandra), we’ve been able to piece together exactly what occurred. Not only that, but observations of a light-echo, or reflected light off of the nearby gas, has allowed us to see the light from this explosion centuries later, and learn exactly how it happened.
72659743
submission
StartsWithABang writes:
You might imagine all sorts of possibilities for how the Universe could have been shaped: positively curved like a higher-dimensional sphere, negatively curved like a higher-dimensional saddle, folded back on itself like a donut/torus, or spatially flat on the largest scales, like a giant Cartesian grid. Yet only one of these possibilities matches up with our observations, something we can probe simply by using our knowledge of how light travels in both flat and curved space, and measuring the CMB, the source of the most distant light in the Universe. The result? A Universe that’s so incredibly flat, it’s indistinguishable from perfection.
72652069
submission
StartsWithABang writes:
The Universe itself is 13.8 billion years old, and yet the most distant galaxies we find are even farther away than 13.8 billion light years. You'd think, if light traveled at the speed of light, that would be the maximum distance anything we'd see could be. But the expansion of the Universe works in a counterintuitive way, enabling objects to actually be up to 46 billion light years away. For those curious, this does not apply to objects bound to us, gravitationally, like the Sun, our stars, or our local group.
72632455
submission
StartsWithABang writes:
When it comes to the Universe, you might think that energy really is only limited by rarity: get enough particles accelerated by enough supermassive, super-energetic sources, and it’s only a matter of time (and flux) before you get one that reaches any arbitrary energy threshold. After all, we’ve got no shortage of, say, supermassive black holes at the hearts of active galaxies. And yes, we do find cosmic rays hundreds, thousands or even millions of times the energy that the LHC can achieve. But when we think about the Universe in detail, these cosmic rays aren’t unlimited in their energy, but are rather stopped in their tracks by the most unlikely of sources: the ultra-low-energy cosmic microwave background, left over some 13.8 billion years after the Big Bang.
72570909
submission
StartsWithABang writes:
You might think that, when it comes to finding the most distant objects in the Universe, all we need is a good telescope, to leave the shutter open, and wait. As we accumulate more and more photons, we’re bound to find the most distant, faint objects out there. Sure, Hubble just broke its own cosmic distance record, but it's certainly not the most distant. Thinking so misses an important fact: the Universe is expanding! And with that expansion, the wavelength of the light we can see gets redshifted. Ultraviolet light winds up in the infrared, infrared light winds up in the microwave, and the most distant galaxies that are out there are invisible, even to Hubble. Here are Hubble's limits, and how the James Webb Space Telescope will overcome them.
72527453
submission
StartsWithABang writes:
As Slashdot has previously reported, NASA Spaceflight has claimed to have vetted the EM Drive in a vacuum, and found there is still an anomalous thrust/acceleration on the order of 50 microNewtons for the device. While some are claiming this means things like warp drive and 70-day-trips-to-Mars are right on the horizon, it's important to view this from a scientist's point of view. Here's what it will take to turn this from a speculative claim into a robust one.
72526457
submission
StartsWithABang writes:
Imagine you just stared into darkness, collecting every photon of light that came by. What would you wind up seeing? The Hubble Space Telescope has done this many times, creating the Hubble Deep Field first and then the Hubble Ultra Deep Field with upgraded cameras and more time. But most recently, the eXtreme Deep Field has surpassed even that. With double the exposure time in the same region as the Ultra Deep Field, we’ve set the most robust lower limit on the number of galaxies in the Universe, and learned what it will take to find the rest.
72467045
submission
StartsWithABang writes:
While it might seem like there are an endless supply of stars in the Universe, the process that powers each and every one requires fuel to burn. At some point — even though it’s far in the future — that fuel will all be spent, and all we’ll be left with are stellar corpses of various types. But the Universe is full of second chances, and opportunities to bring not only burned-out stars back to life, but to give life to the failed stars-that-never-were. Of all the possibilities out there, what’s going to give rise to the very last light in the Universe? The smart money is on colliding and merging (but not inspiraling) failed stars known as brown dwarfs.
72436507
submission
StartsWithABang writes:
It was an idea made famous by the movie Happy Gilmore, but the physics behind it is actually sound: getting a running start, even a slow one, should theoretically be able to improve your driving distance by about 10% off the tee. But there's a big different between physics-in-theory and physics-and-physiology-in-practice, at least, in many cases. This time, however, they line up beautifully, as a running start really can help your golf game!
72403373
submission
StartsWithABang writes:
There are certain words that simply get people’s hackles raised, shutting off the part of their brain that normally responds to reason and instead results in an emotional response taking over. For some, that word is “theory,” one of the words with the biggest gap between its colloquial and scientific uses. But another such term is “consensus.” You might have grown up believing that doing something yourself is the only way to ensure it gets done correctly. But when it comes to science, not only is that not the case at all, but a scientific consensus isn’t the conclusion, but rather the starting point.
72398673
submission
StartsWithABang writes:
Dark matter is necessary to explain the motions of stars, galaxies and the formation of structure in the Universe, but most surprisingly is how its presence and abundance is essential to the existence of life in the Universe. Without dark matter's extra gravitation, heavy elements created in ultra-massive stars would escape from our galaxy in supernova explosions, preventing the formation of rocky planets, liquid oceans, organic molecules, and even life itself.
72367019
submission
StartsWithABang writes:
Stars are some of the most perfect blackbodies in the Universe, meaning that they absorb practically all of the energy incident upon them. So if one star's light shines on another star, it's almost definitely going to be absorbed by that star. But starlight takes hundred of thousands of years to leave a star's core and exit through the surface, does that mean this incident starlight is subject to the same fate? Not at all, and in fact it lasts only two weeks (at most, typically) before getting re-emitted.
72320791
submission
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.
72255657
submission
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.
72246203
submission
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.
