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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 7 months ago

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There is no "you" in a parallel Universe

StartsWithABang StartsWithABang writes  |  yesterday

StartsWithABang (3485481) writes "Ever since quantum mechanics first came along, we’ve recognized how tenuous our perception of reality is, and how — in many ways — what we perceive is just a very small subset of what’s going on at the quantum level in our Universe. Then, along came cosmic inflation, teaching us that our observable Universe is just a tiny, tiny fraction of the matter-and-radiation filled space out there, with possibilities including Universes with different fundamental laws and constants, differing quantum outcomes existing in disconnected regions of space, and even the fantastic one of parallel Universes and alternate versions of you and me. But is that last one really admissible? The best modern evidence teaches us that even with all the Universes that inflation creates, it's still a finite number, and an insufficiently large number to contain all the possibilities that a 13.8 billion year old Universe with 10^90 particles admits."
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There isn't another version of you in a parallel Universe

StartsWithABang StartsWithABang writes  |  yesterday

StartsWithABang (3485481) writes "Ever since quantum mechanics first came along, we’ve recognized how tenuous our perception of reality is, and how — in many ways — what we perceive is just a very small subset of what’s going on at the quantum level in our Universe. Then, along came cosmic inflation, teaching us that our observable Universe is just a tiny, tiny fraction of the matter-and-radiation filled space out there, with possibilities including Universes with different fundamental laws and constants, differing quantum outcomes existing in disconnected regions of space, and even the fantastic one of parallel Universes and alternate versions of you and me. But is that last one really admissible? The best modern evidence teaches us that even with all the Universes that inflation creates, it's still a finite number, and an insufficiently large number to contain all the possibilities that a 13.8 billion year old Universe with 10^90 particles admits."
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Reaching Pluto with an assist from Jupiter

StartsWithABang StartsWithABang writes  |  2 days ago

StartsWithABang (3485481) writes "It’s a taxing enough task to launch something off the surface of the Earth, escaping our planet’s gravity and finding our way into interplanetary space. But to reach the outer Solar System? To go beyond the gas giants and even escape from our Sun’s pull completely? We need a little help to do that. Thankfully, the biggest planet in our Solar System is always ready to lend a helping hand. Or, as it were, an assist of a very particular type: a gravity assist. Here's the story of how we made it to Pluto in a mere nine years, thanks to Jupiter."
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A "comet storm" is in our future, and it isn't pretty

StartsWithABang StartsWithABang writes  |  2 days ago

StartsWithABang (3485481) writes "Out beyond the orbit of Neptune, hundreds of thousands of large, icy bodies stably orbit our Sun, held very tenuously by our Solar System's gravity at such great distances. For the most part, these objects leave us alone, but every once in a while, a star passes close enough to our Solar System to perturb them, sending a great number into the inner Solar System and causing a (potentially life-threatening) comet storm. There's a candidate for a huge one a few hundred thousand years from now, and a certain one coming in about 1.4 million years. Comet defense, anyone?"
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The Big Bang by Balloon

StartsWithABang StartsWithABang writes  |  3 days ago

StartsWithABang (3485481) writes "If you want to map the entire sky — whether you're looking in the visible, ultraviolet, infrared or microwave, your best bet is to go to space. Only high above the Earth's atmosphere can you map out the entire sky, with your vision unobscured by anything terrestrial. But that costs hundreds of millions of dollars for the launch alone! What if you've got new technology you want to test? What if you still want to defeat most of the atmosphere? (Which you need to do, for most wavelengths of light.) And what if you want to make observations on large angular scales, something by-and-large impossible from athe ground in microwave wavelengths? You launch a balloon! The Spider telescope has just completed its data-taking operations, and is poised to take the next step — beyond Planck and BICEP2 — in understanding the polarization of the cosmic microwave background!"
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Finding your longitude on Earth with Jupiter's moons

StartsWithABang StartsWithABang writes  |  4 days ago

StartsWithABang (3485481) writes "If you want to know where you are on Earth, you typically use a GPS or, barring that, other terrestrial landmarks to help determine your location. If you didn't have access to that sort of technology or knowledge, you could still use some well-known objects in the sky to determine your latitude. Longitude, however, is trickier, since it's arbitrarily defined. Perhaps surprisingly, for centuries, the best way to determine it was by using the moons of Jupiter, and watching when they enter/exit the shadow of the giant planet."
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The future of stars like ours, in visuals

StartsWithABang StartsWithABang writes  |  5 days ago

StartsWithABang (3485481) writes "When stars between about 40% and 800% the mass of our Sun run out of hydrogen fuel in their cores, they expand into a red giant phase, burning helium in their center. The intense stellar winds produced blow off the star’s outer layers, and when the core runs out of helium to burn, the central region contracts to a white dwarf, producing intense ultraviolet light that lights up the expelled gas and ions, often found in extremely rare ionization states: a planetary nebula. Here's the story of the Cat's Eye Nebula, one of the closest, most detailed planetary nebulae of all, as told (mostly) through pictures."
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How do we know the timeline of the Universe?

StartsWithABang StartsWithABang writes  |  about a week ago

StartsWithABang (3485481) writes "The history of the Universe happened in a well-known order: inflation ends, matter wins out over antimatter, the electroweak symmetry breaks, antimatter annihilates away, atomic nuclei form, then neutral atoms, stars, galaxies, and eventually us. But scientists and science magazines often publish timelines of the Universe with incredibly precise times describing when these various events occur. Here's how we arrive at those values, along with the rarely-publicized uncertainties."
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How far could Superman hit a baseball?

StartsWithABang StartsWithABang writes  |  about a week ago

StartsWithABang (3485481) writes "With his incomparable superpowers such as strength, speed, and vision, Superman might seem like a model for the greatest athlete of all-time. What if he didn't fly, use his super-breath or eye lasers, but decided to play baseball using only standard equipment? How far would he be able to hit a baseball, limited by the environment of Earth and the laws of physics? A great analysis suggests five-to-six times farther than anyone has ever hit one, but no farther."
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The camera that changed the Universe

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "As the Hubble Space Telescope gets set to celebrate the 25th anniversary of opening its eyes to the Universe, it's important to realize that the first four years of operations were kind of a disaster. It wasn't until they corrected the flawed primary mirror and installed an upgraded camera — the Wide Field Planetary Camera 2 (WFPC2) — that the Universe truly came into focus. From 1993 to 2009, this workhorse camera literally changed our view of the Universe, and we're pushing even past those limits today."
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Science by democracy doesn't work

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "The US Senate just voted on whether climate change is a hoax, knowing full well that debates or votes don't change what is or isn't scientifically true or valid. Nevertheless, debates have always been a thing in science, and they do have their place: in raising what points would be needed to validate, robustly confirm or refute competing explanations, theories or ideas. The greatest scientific debate in all of history — along with its conclusions — illustrates exactly this."
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What kind of stars actually gave rise to us?

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "You've heard the famous quote before, that "we are star stuff." This is true, of course, since only hydrogen and helium existed shortly after the Big Bang, so the elements must have been made in stars. But many of the ones we think of as necessary for life — including phosphorous, sodium, chlorine, magnesium, calcium, potassium, copper, and zinc — didn't come from a single generation of previous, massive stars. It took a slow-burning star like our own Sun to make dozens of elements that are abundant on Earth today."
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Where our Moon came from

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "Almost every planet has bodies orbiting it, but their moons are far and away much, much smaller and less massive than the planet in question. Not so for Earth! For practically all of human history, the largest, nearest object in the skies—the Moon—was a total mystery, and why we had one that was so large and massive compared to our planet. This was even a mystery when we walked on the Moon! Yet now we know it was formed from an impact with another large world in the early Solar System, and we even have pieces of evidence that validate this unique origin for the Moon."
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Why don't planets have the same elements as stars?

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "The stars are the heaviest bound objects in the Universe, yet they're made out of the lightest elements: hydrogen and helium. On the other hand, the light, rocky planets are made out of the heaviest elements, with practically no hydrogen or helium at all. Why is this? There's an incredible story of mass, velocity, temperature and gravitation that brings it all together, and explains not only when but how thick a hydrogen/helium envelope a planet can have."
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How do you figure out your latitude and longitude?

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "If you awoke at any location on Earth, with no idea where you were or when it was, how would you figure out your latitude and longitude? (No GPS.) It's something you can do with only primitive tools, and it turns out that latitude is very easy if you know the night sky well. But longitude? That's a complicated one, but it turns out we can figure it out if we're clever. Here's the story of how."
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Dark matter in galaxies: proven!

StartsWithABang StartsWithABang writes  |  about two weeks ago

StartsWithABang (3485481) writes "If you look at the stars in a galaxy — and then at all the different wavelengths of light that there are — you’d think you can do a good job of reconstructing its mass, and where it’s located. Makes sense, right? Only then, if you take those observations and compare them to how the stars within the galaxy actually move, you’d be shocked to find that what you see isn’t what you get! You might think to invoke dark matter, or you might seek to change the laws of gravity, but there’s a brilliant observational test we can make to tell the two scenarios apart. And for the first time, on the scales of an individual galaxy, we’ve seen the dark matter explanation emerge as the only one that makes sense."
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When Einstein met H.G. Wells

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "When we talk about dimensions, we’re used to thinking of three: something like length, width and depth, or x, y and z. But there’s a fourth dimension as well that’s of paramount importance for our Universe, otherwise everything would simply be static: time. H.G. Wells brought this idea to life in his story The Time Machine in 1895, and years later Einstein brought forth special and general relativity into the world, bringing scientific validity to this theoretical conception. Here's the fascinating background, story and aftermath of when they met in 1929."
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Everything about the cosmic and quantum concepts of "nothing"

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "When we conventionally think about nothing, we imagine removing all the forms of matter and energy from space, and having it be completely empty. If only! Quantum mechanics tells us that even empty space isn't so empty, and that not only is it full of virtual particles, but that the zero-point energy of empty space isn't quite zero. Why is this, and what are the limits of our knowledge about what "nothing" truly is? Sabine Hossenfelder has an exploration of all of this that's worth a read."
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Where does our galaxy's gravity come from?

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "By now, you’ve probably had a lot of opportunities to think about what holds our Universe together: the incredible force of gravitation. Although it’s the weakest known force in the Universe, there seems to be no limit to how much mass you can collect in one place. And so on the largest scales — like solar systems, stars and galaxies — it seems to be the only force that matters. Yet the matter that we see and know of can simply not account for the gravitational force that we see, from its effects on the galaxy to the formation of rocky planets with heavy elements like our own. What’s going on, then? The overwhelming majority of our galaxy's gravity must be coming from a type of dark matter that isn't made of any of the particles we know of."
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There is no center of the Universe

StartsWithABang StartsWithABang writes  |  about three weeks ago

StartsWithABang (3485481) writes "From our vantage point, the Universe is expanding and cooling, with all but a few of the closest galaxies receding from our view. In fact, the farther away an object is, the faster it appears to recede. This may sound an awful lot like what occurs in an explosion to you, especially if it were centered on us. Furthermore, the name “the Big Bang” sure gives that same implication, doesn’t it? Yet despite these facts, it turns out that the idea that the Universe has a center is completely false, and is actually contradicted by both relativity and the Universe that we observe."

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