68031549
submission
StartsWithABang writes:
34 years ago, Carl Sagan became the first person to present — in a format accessible to the entire world — a synthesized story of all the most important scientific points and facts that we had learned about the cosmic story common to us all. No longer did we live in a Universe the size of our galaxy, dominated by Newtonian gravity, but in a Universe billions of years old, with more than 100 billion galaxies in it, that all started with a bang. But since 1980, we’ve learned so much more, and some of the best ideas that Carl knew — about the beginning, middle, and end of the Universe — have actually been improved upon, and the story as it was told in 1980 has been superseded by a more accurate one.
67868621
submission
StartsWithABang writes:
There seems to be a formula for this very specific extraordinary claim: point your high-energy telescope at the center of a galaxy or cluster of galaxies, discover an X-ray or gamma ray signal that you can't account for through conventional, known astrophysics, and claim you've detected dark matter! Only, these results never pan out; they've turned out either to be due to conventional sources or simply non-detections every time. There's a claim going around the news based on this paper recently that we've really done it this time, and yet that's not even physically possible, as our astrophysical constraints already rule out a particle with this property as being the dark matter!
67787279
submission
StartsWithABang writes:
While the coming of winter will inevitably followed by warmer temperature as the Earth's northern hemisphere tilts back towards the Sun again, the Universe isn't so lucky, as it continues its inevitable slide towards absolute zero in temperature. But the Universe won't just end in ice, it will end in ice in the fastest way possible, as the expansion rate will never even drop to zero. Bonus fun fact: 97% of the galaxies in the part of the Universe observable to us are already unreachable, even at the speed of light.
67742967
submission
StartsWithABang writes:
Here on Earth, liquid water is plentiful; our planet has the stable temperatures and pressures that water needs to exist in its liquid state. But what happens if you take that water to space? In the vacuum of space, the temperatures are much too low for liquid water; everything should freeze. But the pressures are much to low for liquid water as well; everything should boil! So which one does it do: does it freeze or does it boil? Surprisingly, it does both; first it boils, then it freezes! Under the right conditions, we can even reproduce this on Earth, too.
67692795
submission
StartsWithABang writes:
Most meteor showers originate from comets well out beyond Neptune, only entering the inner Solar System periodically. In those cases, we have to wait long periods of time for the showers to develop, and suffer many years with paltry displays as we pass through the parts of the comet's orbit thin in particles. But the Geminids are special: they're formed from a short-period asteroid and only began in the mid-19th century. Ever since then they've been intensifying, and conditions are right this year for the most spectacular display of all time. Come catch 2014's greatest meteor shower, including where to look, when, and where to go online in case of clouds!
67649373
submission
StartsWithABang writes:
From the video channel's description: "We live on a small, wet, rocky world where life has flourished. But there are hundreds of billions of stars out there in our galaxy alone, and our galaxy is just one of hundreds of billions in our observable Universe.
There were a huge number of things that occurred — from the very beginning up through the present day — that resulted in our world, and ourselves, existing as it all does today. How did all of this come to be? And where does all this come from?
Theoretical astrophysicist Ethan Siegel guides us, one aspect at a time, through the most cosmic of journeys, by sharing the story the Universe tells us about itself."
Episode 1 is on organic molecules: watch it here.
67525153
submission
StartsWithABang writes:
It’s easy to visualize a magnetic field if you’ve got a set of iron filings and a laboratory to experiment in, but what about the distant stars? What of entire galaxies? They’re thought to have magnetic fields, just as our Sun does. But we can’t measure the coronal loops so easily for objects thousands, millions or billions of times as distant. Yet, we have our techniques, based on how charged particles and light interact with magnetic fields. Come see how we map the Universe’s magnetism from afar!
67484085
submission
StartsWithABang writes:
You might think there's very little that Earth and Mars have in common, with our planet covered in water, with a thick atmosphere, active magnetic field and teeming with life, while Mars is a dry, cold, barred desert world that's incapable of liquid water. But for the first one or two billion years of its existence, Mars likely had liquid water and all the right conditions for life. What happened? The leading theory says that Mars cooled, lost its magnetic field, and had its atmosphere stripped away by the solar wind, and NASA's MAVEN mission is about to take the data to either validate or falsify this hypothesis!
67441029
submission
StartsWithABang writes:
Nearly a century ago, Pluto was discovered, and for 48 years it remained the only known object whose orbit takes it beyond the gravitational pull of Neptune. In a single generation, we've now discovered more than 1,000 additional objects in the Kuiper Belt, but does that make Pluto any less special? A strong argument for why Pluto might matter now more than ever.
67400649
submission
StartsWithABang writes:
Earlier this year, the BICEP2 team shook up the world by announcing the discovery of primordial gravitational waves: a signal from the earliest stages of the Universe, going all the way back to before the Big Bang! By looking at the photon polarization data, they claimed to have surpassed the gold “5” standard for announcing a discovery in physics. But recently, that’s been walked back, as there could have been a systematic error at play: simple emission from our own Milky Way. Later this month, the Planck team will release their results, and either confirm or refute BICEP2. Here’s where we stand on the eve of that announcement.
67342869
submission
StartsWithABang writes:
After 110 consecutive weeks highlighting each one of the Messier objects, astrophysicist Ethan Siegel has completed a virtual online tour of the entire catalogue, with the greatest (publicly available) images and mosaics of each object available in a single, scrollable article. Time well spent!
67222117
submission
StartsWithABang writes:
If the Universe is expanding and cooling, it’s easy to visualize how radiation cools: it has a wavelength, space expands, and so as the wavelength gets stretched, the energy drops. But what about the matter? Energies must have dropped for matter as well, otherwise it wouldn’t have lost enough kinetic energy to become gravitationally bound into gas clumps, stars and galaxies. And yet, those things very much exist! What’s the resolution to this? The incredible answer is here.
67151741
submission
StartsWithABang writes:
Today (Thursday), the fourth Thursday of November, marks American Thanksgiving, an annual harvest festival and feast where we celebrate a variety of things, particularly the good things that have come to us in life. And yet, what’s amazing is that—if you’re willing to start with expanding spacetime and the laws of physics—a Universe that looks a whole lot like ours, complete with clusters, galaxies, stars, planets, heavy elements, and, most probably, life, is inevitable. And it’s inevitable all over the Universe. Be thankful for that!
67114719
submission
StartsWithABang writes:
With every extra digit we add in our quest for absolute zero, more and more of the Universe becomes accessible to us. One of the holy grails of this will be to measure the inherent line width of the spin-flip transition of atomic hydrogen, perhaps the narrowest of all emission lines. If we can go even deeper than that, probing its structure over time, we could wind up seeing signatures of phenomena such as gravitational waves, a time-varying gravitational constant or black hole formation. We're waiting on the experimentalists to get us there, but in theory, this is happening all the time.
67067049
submission
StartsWithABang writes:
Accelerated by some unknown mechanism, the highest energy particles in the entire Universe come from all over the sky with energies exceeding 10^19 eV, or more than a million times the energies achieved at the LHC. On the flipside, the lowest energy radio waves are emitted by an ultra-rare transition of hydrogen atoms, and may provide a window into the Universe from before the first stars formed. Come learn about the highest and lowest energy signals from the Universe, and why they matter for our understanding of it all.
