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Where will we all be in 100 billion years?

StartsWithABang Oops (1 comments)

That should read "100 billion years from now", not "100 billion years ago". My typo.

about 2 months ago

Submissions

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Solving the mystery of ancient stars with too many heavy metals

StartsWithABang StartsWithABang writes  |  yesterday

StartsWithABang (3485481) writes "When you think about the stars in the sky, it takes some study to realize that the bluest, brightest stars are also the shortest lived. So when we look at a cluster of stars — or any stellar population — we can figure out how old it is by looking at the color and magnitude of the brightest, bluest main-sequence stars that are still alive. In general, the oldest objects are the reddest globular clusters, which formed when the Universe was only a few hundred million years old. Because the Universe was mostly hydrogen and helium at the time, enriched by relatively few generations of stars, these clusters tend to have very small amounts of heavy elements like iron, sometimes as little as 1% of what’s in our Sun. So when a star cluster has a color/magnitude diagram that says it's very old but a heavy element abundance that says it's relatively young, who wins? We all do, by learning more about how, when and where atomic riches accumulate in galaxies!"
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How long has the Universe been accelerating?

StartsWithABang StartsWithABang writes  |  4 days ago

StartsWithABang (3485481) writes "Although dark energy has always been present in the Universe, it didn't come to dominate the Universe's energy content until recently. But even before that, its effects on the Universe's expansion rate could be felt, and it caused distant galaxies to begin accelerating away from us. Thanks to the precision measurements that have come out since the Planck satellite, we're now able — for the first time — to pinpoint with tremendous accuracy exactly when the Universe transitioned from a decelerating to an accelerating state. Come have your misconceptions about dark energy and cosmic acceleration cleared up here. (And no, the expansion rate itself isn't increasing; it's still going down!)"
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Back to school advice for STEM students

StartsWithABang StartsWithABang writes  |  5 days ago

StartsWithABang (3485481) writes "Labor Day is this coming Monday, and that means the new school year is about to start. Whether you are or whether you know a young person, say in middle-or-high school, you’re likely very close to someone facing a lot of uncertainty about not only their future, but about their present. Who can be expected to know exactly what they want to do and exactly how to get the most out of it when they’re only a teenager? Yet that’s what we expect most students to do. For students that are interested in STEM — science, technology, education and mathematics — the pressure is even greater. So what advice should you give them? Here’s a great start, from someone who’s been there and who’s helped a generation of kids go through it!"
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Could Dark Matter just be Normal Stuff that's Dark?

StartsWithABang StartsWithABang writes  |  5 days ago

StartsWithABang (3485481) writes "When you look out into the Universe at distant galaxies, at clusters of galaxies or at the Universe on the largest scales, what you see is the luminous stuff, which is pretty exclusively stars and stellar-related objects. But based on what we know about gravitation on those scales, we know there’s got to be much more mass than that, most of which doesn’t emit light: dark matter. It seems like a great leap to presume that there’s a new type of matter out there accounting for these observations. Could normal, non-luminous matter possibly account for all the dark matter? No, and here’s why it can't!"
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The Stars Beyond

StartsWithABang StartsWithABang writes  |  about a week ago

StartsWithABang (3485481) writes "You've no doubt heard of dark matter halos around galaxies: vast, extended, spherical collection of mass that reach for hundreds of thousands of light-years beyond what we typically think of as a spiral or elliptical galaxy. But did you know that galaxies contain vast, extended stellar halos as well? Moreover, they look nothing like you'd expect! They're not spherical or even ellipsoidal, but highly irregular, and have an awful lot to teach us about how galaxies came to be the way they are today."
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The Brilliance of Scientific Assumption

StartsWithABang StartsWithABang writes  |  about a week ago

StartsWithABang (3485481) writes "If you’ve ever heard someone dismiss evolution, the Big Bang or climate change as “just a theory” and wanted to pull your hair out, you’re not alone. In science, after all, theories are the most powerful ideas we have to explain the mechanism behind the most intricate observable phenomena in the Universe. But it’s where our theories fail, or at the fringes, where observations-or-experiments might disagree with the best theoretical predictions, that progress is made. This tantalizing border between the known-and-understood and the next undiscovered frontier are something we only cross by challenging our most cherished assumptions. Here are some of our most sacred fundamental assumptions, and how we're probing them for the next great leap forward!"
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Astrology is not a science

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "It's a beautiful idea, the notion that the Earth isn't simply affected by the Sun and the Moon, but by the locations and positions of our planet relative to the others in our Solar System and to the stars as well. But there are many beautiful ideas that don't describe reality; those fall squarely into the category of pseudoscience. So what's the deal with astrology? How does it stand up to scientific scrutiny, and can we truly say that it's wrong, or only that there's not yet an observed significance to it?"
Link to Original Source
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The first particle physics evidence of physics beyond the Standard Model?

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "It’s the holy grail of modern particle physics: discovering the first smoking-gun, direct evidence for physics beyond the Standard Model. Sure, there are unanswered questions and unsolved puzzles, ranging from dark matter to the hierarchy problem to the strong-CP problem, but there’s no experimental result clubbing us over the head that can’t be explained with standard particle physics. That is, the physics of the Standard Model in the framework of quantum field theory. Or is there? Take a look at the evidence from the muon’s magnetic moment, and see what might be the future of physics!"
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The independent lines of evidence that make dark matter all but unavoidable

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "When you hear about dark matter, you very likely put it up there with string theory in the pantheon of "well, that's a nice idea, now call me when you find it" style of scientific ideas. After all, direct detection of dark matter has proved elusive, despite many arduous experiments designed specifically to find it. Yet we continue to look, convinced that it exists. Why? Because of several compelling, independent lines of evidence that all point towards dark matter's existence. Here are the top five, and take note, modified gravity fans, that your best "theories" can only explain one out of the five!"
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Why didn't the Universe become a black hole?

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "With some 10^90 particles in the observable Universe, even stretched across 92 billion light-years today, the Universe is precariously close to recollapsing. How, then, is it possible that back in the early stages after the Big Bang, when all this matter-and-energy was concentrated within a region of space no bigger than our current Solar System, the Universe didn't collapse down to a black hole? Not only do we have the explanation, but we learn that even if the Universe did recollapse, we wouldn't get a black hole at all!"
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The Milky Way's Most Recent Supernova That Nobody Saw

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "The last two naked-eye supernovae changed the world: Tycho Brahe's supernova of 1572 and Kepler's of 1604 literally ushered in the modern age of astronomy, and yet despite the fact that supernovae occur about once-per-century in galaxies, we've never seen another Milky Way supernova since. But surprisingly, they've still been happening! It's only the fact that we're in the plane of the galaxy, whose dust blocks the visible light from such a large fraction of our neighboring stars, that's prevented us from seeing them. But we can look beyond visible light now, and have discovered at least two more recent ones since, including one that happened as recently as the 1860s!"
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How the Universe grew up... and stopped.

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "There once was a time when there were no stars, no galaxies, and no groups or clusters. These all formed, so at some point, the Universe was able to build these structures where there were none before. But today, everything that isn’t already gravitationally bound to itself never will be. How did we go from a perfectly uniform Universe to an almost perfectly uniform one, to one with stars, galaxies, and clusters, to one that won't result in any new gravitationally-bound structures anymore? The physics of gravitational growth (and its end); a fascinating story."
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The Smallest Possible Scale in the Universe

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "It's a question that goes back as far as inquiry about the physical world itself: is there a smallest, fundamental scale in the Universe? Yes, it's true that quantum theory tells us there's a limit to the resolution that we can measure (thanks, Heisenberg), but does that necessarily imply that there's a fundamental limit inherent to space (or physics) itself? Not necessarily, argues a new book from Amit Hagar, although both options are possibilities. Theoretical physicist Sabine Hossenfelder has a great take on it, exploring both sides and taking us right up to the edge of what is known."
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Do Dark Matter and Dark Energy cast doubt on the Big Bang?

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "Back in the 1960s, after the discovery of the Cosmic Microwave Background, the Big Bang reigned supreme as the only game in town. But back then, we also assumed that what we consider as "normal matter" — i.e., protons, neutrons and electrons — was, along with photons and neutrinos, the only stuff that made up the Universe. But the last 50 years have shown us that dark matter and dark energy actually make up 95% of the energy composition of our cosmos. Given that, is there any wiggle room to possibly invalidate the Big Bang?"
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The meteors you've waited all year for

StartsWithABang StartsWithABang writes  |  about a month ago

StartsWithABang (3485481) writes "It's finally here! Sure, we witnessed the birth of a new meteor shower earlier this year, but it was a flop. Many other showers have come-and-gone like they do every year, but none of them have given us a significant number of meteors-per-hour. But even with a near-full Moon out, it's finally time for the Perseids, the most reliable meteor shower year-after-year. Here's where to find them, where they come from and a whole lot more, including some surprising facts about where they don't come from: cometary tails!"
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Why the 'NASA tested Space Drive' is Bad Science

StartsWithABang StartsWithABang writes  |  about a month ago

StartsWithABang (3485481) writes "Just over a century ago, N rays were detected by over a hundred researchers and discussed in some three hundred publications, yet there were serious experimental flaws and experimenter biases that were exposed over time. Fast forward to last week, and NASA Tests Microwave Space Drive is front page news. But a quick analysis shows that it isn't theorists who'll need to struggle to explain this phenomenon, but rather the shoddy experimentalists who are making the exact same 'bad science' mistakes all over again."
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The Man Who Invented the 26th Dimension

StartsWithABang StartsWithABang writes  |  about a month ago

StartsWithABang (3485481) writes "Based on all the experiments we've ever been able to perform, we're quite certain that our Universe, from the largest scales down to the microscopic, obeys the physical laws of three spatial dimensions (and one time dimension): a four-dimensional spacetime. But that's not the only possibility mathematically. People had experimented with bringing a fifth dimension in to unify General Relativity with Electromagnetism in the past, but that was regarded as a dead-end. Then in the 1970s, an unknown theoretical physicist working on the string model of the strong interactions discovered that by going into the 26th dimension, some incredibly interesting physics emerged, and thus String Theory was born!"
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Where does cosmic rotation come from?

StartsWithABang StartsWithABang writes  |  about a month ago

StartsWithABang (3485481) writes "From the smallest scales to the largest, everything in the Universe spins and revolves. This is a good thing for galaxies and solar systems, otherwise there would be no such thing as planets or stars, as everything would simply collapse down into static, catastrophically massive-and-dense objects. But the Universe — as far as we can tell — wasn't born with any intrinsic angular momentum. And yet, everything rotates and revolves! Where did this cosmic rotation come from? From gravitation, the inevitable physics of torques, and the conservation of angular momentum."
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An atom in the Universe

StartsWithABang StartsWithABang writes  |  about a month ago

StartsWithABang (3485481) writes "It took 13.8 billion years of cosmic evolution and some 75 trillion cells consisting of 10^28 atoms to make you. About six years from now, you'll still be you, with the same number of cells, but practically none of those same atoms will still be in your body. Each one, though, as fleeting as it is, has its own unique cosmic story. Here's that story for just one of them, and yet, it's somehow the story of them all as well."
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How are neutron stars magnetic?

StartsWithABang StartsWithABang writes  |  about a month ago

StartsWithABang (3485481) writes "The first (and simplest) force to be understood was gravity: there's only one type of mass (positive), it's always attractive, and it works the same on everything. The second force was electromagnetism: there are two types of charges (positive and negative), and the charged particles experience forces either in the presence of an electric field or from moving through a magnetic field. And magnetic fields can only be made when you have moving-or-spinning charged particles. So why is it, then, that a neutron star — a star made up of uncharged neutrons — has one that's a trillion times stronger than Earth's? As it turns out, neutron stars are both layered and aren't made of such neutral things after all, which make for some interested physics!"

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