60555785
submission
StartsWithABang writes:
So maybe you've been convinced — from galaxies, clusters, big bang nucleosynthesis, the cosmic microwave background and the large-scale structure of the Universe — that the Universe really does need dark matter. But we always talk about our Universe as being full of cold dark matter. How do you take the temperature of something you can't directly interact with, though? Starts with a bang has the answer.
60375627
submission
StartsWithABang writes:
Even with the add-ons of dark matter, dark energy and inflation, the Big Bang still thrives as the most successful scientific model of the Universe ever constructed. It not only accounting for phenomena like the abundance of the light elements, the cosmic microwave background, and the Universe's large-scale structure, but it's led to observable predictions about their details that have since been verified. But there’s one thing the Big Bang has generically predicted that we haven’t been able to test: a cosmic background of low-energy, relic neutrinos. Starts With A Bang has the scoop.
60361537
submission
StartsWithABang writes:
For thousands of years, there were three known possibilities concerning the origin of the Universe: it had a moment at which it sprang into existence, it had always existed eternally into the past, or it was a cyclical, repeating entity. In the 20th century, observations appeared to vindicate the Big Bang theory as the origin of our Universe, but more recently, we've learned that the Hot Big Bang was preceded by a period of cosmic inflation, and wasn't the origin of time after all. So how did the Universe get its start? A great walk through what we know, and what the viable possibilities are.
60296531
submission
StartsWithABang writes:
Here on Earth, we think of shooting stars and meteor showers as things that happen periodically; sometimes they’re spectacular, sometimes they’re rare. But in all cases, they’re caused by comet debris, and they should flare up each time the Earth crosses the comet’s path. But as it turns out, every meteor shower had a point in its past where it happened for the very first time. In all of human history, we’ve never recorded one that occurred for the very first time where none happened before. Well, for those of you who want to take the chance to be a part of it, this coming Friday night/Saturday morning, look for the Camelopardalids, making their Earthly debut this year!
60147543
submission
StartsWithABang writes:
Some of you may have seen this viral video of the Solar System's motion through the galaxy. While it's beautiful, no doubt, just how scientifically accurate is it? With the exception of only a few qualitatively (not quantitatively) correct facts, the video butchers almost everything we know about motion, from orbital mechanics to relative speeds to precession to the stellar wind to the Sun's actual path through the galaxy. Come and see what the science actually has to say about all these things!
60103039
submission
StartsWithABang writes:
You’ve all had the experience: you’re all excited to microwave your favorite snack. So you pull it out of the freezer, you throw it in, and you let it rip. A minute or two later, you pull it out, and there it is: boiling on the outside, frozen in the middle. Finally, a physicist answers the eternal question: why do microwaved foods remain frozen on the inside when they reach scalding temperatures on the outskirts? Starts With A Bang explains the whole phenomenon. Bonus for the crisping sleeve explanation!
60021729
submission
StartsWithABang writes:
A couple of months ago, the BICEP2 results were released, announcing the discovery of B-mode polarization in the cosmic microwave background due to gravitational waves left over from inflation. There's a rumor going around now that this result might be due to the Milky Way, and not due to inflation after all. We're going to check (and find out), of course, but if BICEP2's earlier announcement turns out to be wrong, will that force us to re-evaluate inflation's role in the early Universe? Probably not, says Starts With A Bang.
59866079
submission
StartsWithABang writes:
If you have two identical particles, you can put as many of them as you want in the exact same quantum state, so long as they're Bosons. If they're Fermions, on the other hand, they're subject to the Pauli Exclusion Principle, meaning that no two identical Fermions can occupy the same quantum state. What does this mean for the formation of hydrogen molecules from two hydrogen atoms? Surprisingly, not every pair of hydrogen atoms can successfully bind together! Starts With A Bang has the scoop, along with a clear explanation of how come you'll never have more than two hydrogen atoms binding together!
59856345
submission
StartsWithABang writes:
If you looked at all the light from all the stars, clusters and galaxies in the Universe, you could figure out how much mass in the Universe had formed stars. And if you looked at how gravitation worked over the Universe's history, you could figure out how much total mass there was. These numbers differ by a factor of 50, and that's the dark matter problem. But why do we think that this dark matter has to be a new type of particle that not only isn't protons, neutrons and electrons, but can't be anything in the Standard Model? Come read the whole story on dark matter and see for yourself.
59802649
submission
StartsWithABang writes:
Since as far back as the 1930s, observations of the largest structures in the Universe have shown us that there's a discrepancy between the amount of mass that can be inferred from the starlight we see and the amount of mass that we know must be there due to its gravitational effects. Either there's some new, unseen form of matter that isn't present in the Standard Model of particle physics — dark matter — or the laws of gravity are wrong and need to be modified. The leading candidate for the latter option is TeVeS, the first relativistic formulation of MOdified Newtonian Dynamics (MOND). Well, the first observational test capable of distinguishing between TeVeS and General Relativity is complete. Spoiler: Einstein wins again.
59793631
submission
sciencehabit writes:
In the most detailed effort yet, astrophysicists and cosmologists have modeled the evolution of the universe right down to the formation of individual galaxies. The results of the mammoth computer simulation neatly match multiple astronomical observations, ranging from the distribution of galaxies in massive galaxy clusters to the amounts of neutral hydrogen gas in galaxies large and small. The findings once again neatly confirm cosmologists' standard theory of the basic ingredients of the universe and how it evolved—a result that may disappoint researchers hoping for new puzzles to solve.
59768893
submission
StartsWithABang writes:
In 1818, the French Academy of Sciences held a contest to explain the nature of light. One of the entrants was Fresnel, who put forth an elaborately advanced model that light was a wave. One of the judges was Simeon Poisson, passionate defender of Newton's corpuscular model, who showed that Fresnel's results absurdly predicted that light shone around a circular obstacle would result in a bright spot at the center, and basically had Fresnel laughed out of the room. But he committed the cardinal sin of drawing that conclusion without anyone actually performing the crucial experiment! Thankfully, François Arago was there to set things right.
59672569
submission
StartsWithABang writes:
For those of us living in or around large cities — and that's most of us — we're completely divorced from dark, clear night skies as part of our routine experience. But even though our skies may typically rate a seven or higher on the Bortle Dark Sky Scale, that doesn't mean that significantly darker skies aren't accessible. Here's how to install an interactive light pollution map for yourself, and find the darkest skies near you no matter where you are! (North American-centric, but resources are provided for those elsewhere in the world.)
59663809
submission
StartsWithABang writes:
For normal matter — things like protons, neutrons and electrons — there's a fundamental limit to the number of particles you can fit into a given region of space thanks to the Pauli exclusion principle. But photons aren't subject to that limit; in theory, you could cram an infinite number of them into the same exact state. In principle, then, couldn't you create a laser (or lasing cavity) with an infinite amount of energy inside? Perhaps, but there are some big challenges to be overcome!
59597363
submission
StartsWithABang writes:
If the B612 Foundation had its way, we'd be investing a tremendous amount of resources into asteroid detection and deflection technology. After all, even though the risks of getting killed by an asteroid strike are quite low, the consequences of a major asteroid threat are catastrophically high. But science provides us a way out of this: quantify what the risks actually are! Here is the quantitative, scientific truth about asteroids.
