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.
67057691
submission
StartsWithABang writes:
When you think of the origin of life, you probably think about the atoms coming together to make molecules, the molecules coming together to make self-replicating, information-encoded strands, and how all that took place here on Earth. But you might want to consider a different point of view. Try thinking about the fact that those complex atoms need to be created and recycled into new generations of stars, which requires stars to live, die, expel that processed matter back into the interstellar medium, and to have it incorporated into future generations of star systems. Simply having the primordial ingredients wouldn’t give rise to anything interesting. Without dark matter, the structures enabling this wouldn't have been able to form at all, but with it, everything is possible!
66940577
submission
StartsWithABang writes:
Finite to the past, infinite to the past, or cyclical in nature: those are the three options for the nature of our spacetime. We can trace our Universe's history back billions of years, to the earliest moments of the Big Bang and even before to the epoch of cosmic inflation that preceded it, but was there truly a singularity from which space-and-time emerged? Here's the limits of our knowledge on that front.
66854543
submission
StartsWithABang writes:
There’s a problem with our view of the night sky: beautiful though it is, we’re incapable of seeing with our own eyes what the Universe is like from an outsider’s perspective. No matter where we are, we’re stuck inside our own galaxy, with all its light-blocking and obscuring properties. But there’s a trick to seeing through it: some wavelengths of light are more transparent to our galaxy’s material than others! And when we get there — when we view it — the rewards are incomparable, including what we learn about what’s there in our own Universe. A great busting of the myth that if we were plunked down at random, we probably wouldn't see a single galaxy.
66799157
submission
StartsWithABang writes:
After successfully landing on a comet with all 10 instruments intact, but failing to deploy its thrusters and harpoons to anchor onto the surface, Philae bounced, coming to rest in an area with woefully insufficient sunlight to keep it alive. After exhausting its primary battery, it went into hibernation, most likely never to wake again. We’ll always be left to wonder what might have been if it had functioned optimally, and given us years of data rather than just 60 hours worth. The thing is, it wouldn’t have needed to function optimally to give us years of data, if only it were better designed in one particular aspect: powered by Plutonium-238 instead of by solar panels.
66750569
submission
StartsWithABang writes:
The particles of the standard model, some type of dark matter and dark energy, and the four fundamental forces. That’s all there is, right? But that might not be the case at all. Dark energy may not simply be the energy inherent to space itself, but rather a dynamical property that emerges from the Universe: a sort of fifth force. This is speculation that's been around for over a decade, but there hasn't been a way to test it until now. If this is the case, it may be accessible and testable by simply using presently existing vacuum chamber technology!
