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Ethan Siegel
43,661 followers -
Science writer, professor and theoretical astrophysicist
Science writer, professor and theoretical astrophysicist

43,661 followers
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“[W]hy don’t we evaluate building a “sun screen” in space to alter the amount of light (energy) earth receives? Everybody who did feel a total eclipse knows temperature goes down and light dims. So the idea is to build something that would stay between us and sun all year long…”

The Earth’s temperature is rising: that’s a fact. The overwhelming cause of this warming is human-caused emissions of greenhouse gases, like CO2 and methane. The CO2 concentration has now passed 410 parts per million, an increase of over 50% over pre-industrial revolution levels. If we cannot or will not reverse what’s driving the temperature change, we could instead try to counteract it. One proposal is to put a large device in space, between the Sun and the Earth, to block some of the incoming sunlight. As it turns out, blocking 2% would be enough to completely counteract the effects of human-caused global warming. Modifying our atmosphere is risky, but placing a sun screen in space to do the job has only one real drawback: its expense.

But how expensive is it, truly, when you consider the positive effects it would have on the planet? Let’s consider what it would take to combat global climate change by putting a shade in space!
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“To move quickly between two points in space, then, even a straight line might be a disastrous plan. If what you need to do is avoid a large number of potentially hazardous objects, going around might be the only option. This could mean adding a very large distance to your expected path length, perhaps adding many light years to your journey. A straight-line path might be much shorter, but much more dangerous. But the shortest path of all won’t be a straight line, but an intricately curved path through the densest, most dangerous environment of all: a field of stars, planets, black holes, gas, dust, and more. To make the Kessel Run, the Millennium Falcon may have had to go through the center of that legendary galaxy far, far away.”

Was the Kessel Run a legend concocted by Han Solo to try and trick Luke and Obi-Wan? Or was it really a long run, that somehow the Millennium Falcon made in a shorter distance than was ever thought possible? That last possibility is intriguing, because physics allows it to be so. You normally think that the shortest distance between two points is a straight line, but this isn’t so in General Relativity. In truth, a curved path may be shorter, owing to the simple fact that masses are present, and they curve the fabric of spacetime. It’s possible that understanding the force in Star Wars may not be as important, even for a pilot, as understanding the gravitational force in a galaxy far, far away.

Come see how a trick of Einstein’s Relativity might have made the Kessel Run possible!
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“5.) Maps of what’s happening and where. This is perhaps the greatest resource for determining what’s occurring and where. They show fissures and flows, including present, recent, and past lava flows. They display thermal maps of the fissure system and the lava flows that have occurred, overlaid atop satellite imagery. Occasionally, they have radar images that show how things like the eruptive vent at the summit has changed over the past few weeks. Most importantly, they have updated flow fronts, lava pools, lava channels, and ocean entry points. This way, you can know not only where the lava is at any moment, but where the lava flows are headed, and how that’s changed over time.”

On May 3rd, 2018, new cracks and fissures opened up around Kilauea on the Big Island of Hawaii, creating new flows and channels of lava. The next day, a magnitude 6.9 earthquake occurred: the largest in Hawaii in over 40 years. Since then the Kilauea eruption has intensified to rival its highest levels of the past century, with dangers coming from lava flows, channels, and fountains, vog and noxious gases, and volcanic ash. Despite these incredible dangers, however, there’s little worry that this will become as disastrous or deadly as the legendary 1790 eruption, despite the fact that hundreds of times as many people live on Hawaii now as did back then. Why? The incredible work of the USGS Hawaiian Volcano Observatory in collecting and disseminating information.

Find out all that you can learn, and where, about the latest results and updates on the Kilauea eruption from the most trusted source in the game.
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“Tajmar’s results are exactly what you’d expect for the systematic error explanation: with a properly shielded apparatus, with no additional electromagnetic fields induced by the wires, there is no observed thrust at any power. They conclude that these induced fields by the electrical wires, visibly present in the other setups, are the likely culprit for the observed, unexplained thrust:

‘Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper µN thrust measurements for these type of devices.’

To the best of our knowledge, then, rockets will still require propellant. The EmDrive isn’t a reactionless drive at all, and all the laws of physics should still work. In short, we fooled ourselves.”

For years, many tinkerers and inventors have been claiming that some sort of electromagnetic cavity, e.g., the EmDrive, can create a reactionless drive. That is, they claim they can change the momentum of a rocket without any sort of change-in-momentum of anything else, violating Newton’s action-reaction law. Needless to say, much like perpetual motion, physicists are largely skeptical. But until now, we hadn’t yet found why they were achieving the results that they did. However, a new source of error was just uncovered: magnetic fields originating from the cables that power the device. Properly set up the device, away from cables and loops of wires, as Martin Tajmar’s team did, and guess what: your ‘anomalous thrust’ disappears.

The EmDrive, billed as NASA’s impossible space engine, really was too good to be true.
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“In 2003, scientists discovered an object beyond Neptune that was unlike any other: Sedna. While there were larger dwarf planets beyond Neptune, and comets that would travel farther from the Sun, Sedna was unique for how far it always remained from the Sun. It always remained more than twice as distant from the Sun as Neptune was, and would achieve a maximum distance nearly 1,000 times as far as the Earth-Sun distance. And despite all that, it’s extremely large: perhaps 1,000 kilometers in diameter. It’s the first object we’ve ever found that might have originated from the Oort cloud. And we’ll only get two chances if we want to send a mission there: in 2033 and 2046. Right now, there isn’t even a proposed NASA mission looking at the possibility. If we do nothing, the opportunity will simply pass us by.”

Out beyond the eight planets of our Solar System, a large number of regions, all containing frozen objects, are theorized to exist. Innermost is the Kuiper belt, consisting of a wide variety of bodies, but all of which come quite close to Neptune’s orbit and feel its gravitational influence. Beyond that are the scattered disk objects: objects kicked by one of the gas giants out to greater distances. Beyond that are the detached objects, which have undergone multiple gravitational interactions and no longer come close to Neptune. And finally, there are the sednoids: objects that never come within double the Sun-Neptune distance of the Sun. There are only two known, and the first one, Sedna, is so large that it’s surely a dwarf planet. With an aphelion of approximately 1000 A.U., it may well have an origin in the inner Oort cloud, which is hitherto only theorized.

Fantastically, we have two launch windows for a mission to Sedna, if we were interested in going. Why are we not clamoring for this mission, and for the potential chance to explore the Oort cloud for the first time?!
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“There are a massive variety of star-forming regions nearby, and Hubble’s new Legacy ExtraGalactic UV Survey (LEGUS) is now the sharpest, most comprehensive one ever. By imaging 50 nearby, star-forming spiral and dwarf galaxies, astronomers can see how the galactic environment affects star-formation.”

Within galaxies, new stars are going to be formed from the existing population of gas. But how that gas collapses and forms stars, as well as the types, numbers, and locations of the stars that will arise, is highly dependent on the galactic environment into which they are born. Dwarf galaxies, for example, tend to form stars when a nearby gravitational interaction triggers them. These bursts occur periodically, leading to multiple populations of stars of different ages. Spirals, on the other hand, form their new stars mostly along the lines traced by their arms, where the dust and gas is densest. Thanks to the Hubble Space Telescope, we’re capable of finding these stars and resolving them individually, using a combination of optical and ultraviolet data.

The best part? These are individually resolved stars from well outside our own galaxy: in 50 independent ones. Here’s what Hubble’s new LEGUS survey is revealing.
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“If intelligent life re-emerges in our solar system in a few billion years, only a few points of light will still be visible in the sky. What kind of theory of the universe will those beings concoct? It is almost certain to be wrong. Why do we think that what we can view now can lead us to a “correct” theory when a few billion years before us, things might have looked completely different?”

Incredibly, the Universe we know and love today won’t be the way it is forever. If we were born in the far future, perhaps a hundred billion years from now, we wouldn’t have another galaxy to look at for a billion light years: hundreds of times more distant than the closest galaxies today. Our local group will merge into a single, giant elliptical galaxy, and there will be no sign at all of young stars, of star-forming regions, of other galaxies, or even of the Big Bang’s leftover glow. If we were born in the far future, we might miss the Big Bang as the correct origin of our Universe. It makes one wonder, when you think about it in those terms, if we’re missing something essential about our Universe today? In the 13.8 billion years that have passed, could we already have lost some essential information about the history of our Universe?

And in the far future, might we see something that, as of right now, hasn’t yet grown to prominence? Let’s explore this and see what you think!
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“We cannot rely on individual departments or colleges/universities to protect the victims of academic bullying or harassment. Decades of inaction and inadequate action have shown that senior faculty members will continue to engage in unacceptable behavior unless there are real consequences that threaten to take their power away. Their academic careers, however, are based in their ability to successfully publish their work and results in prestigious and meritorious journals, and therefore it is truly the publishers who hold the power to police their actions. If we are serious about solving our bullying and harassment problems, and making scientific research opportunities truly the open and merit-based game we idealize them to be, we can take this next great step. We can not only condemn, but forbid, the unacceptable behavior that continues to cost our fields so many of our best and brightest minds.”

A great number of promising scientific careers have been derailed not based on the scientific merits of the young researcher in question, but rooted in the harassment and bullying they’ve had to endure. When a senior, more powerful professional makes the choice to bully or harass a junior individual, there is usually little recourse the victim can take. Filing a complaint usually harms the victim’s career more than the perpetrator. Despite the existence of Title IX, the policies of colleges and universities are mostly toothless, and designed to protect the institution, not the victim. But if they wanted to, scientific publishers could change the game immediately. By placing a ban on who is allowed to author papers based on violations of their codes of ethics/conduct, they could essentially punish the perpetrators in the one way they’d actually care about the most: in a way that harms their scientific legacy.

Take a look at a new proposal to end bullying and harassment in the sciences. I am sure it’s not perfect, but it’s the most revolutionary step towards protecting people of all genders, colors, and religions from bullying, harassment, and abuse ever seriously considered.
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“Scientists have just confirmed the second most distant galaxy of all: MACS1149-JD1, whose light comes from when the Universe was 530 million years old: less than 4% of its present age. But what’s remarkable is that we’ve been able to detect oxygen in there, marking the first time we’ve seen this heavy element so far back. From the observations we’ve made, we can conclude this galaxy is at least 250 million years old, pushing the direct evidence for the first stars back further than ever.”

When it comes to the most distant galaxies of all, our current set of cutting-edge telescopes simply won’t get us there. The end of the cosmic dark ages and the dawn of the first cosmic starlight is a mystery that will remain until at least 2020: when the James Webb Space Telescope launches. Using the power of a multitude of observatories, we’ve managed to find a gravitationally lensed galaxy whose light comes to us from over 13 billion years ago. But unlike previous galaxies discovered near that distance, we’ve detected oxygen in this one, allowing us to get a precise measurement and to estimate its age.

For the first time, we have evidence from galaxies, directly, that the Universe’s first stars formed no later than 250 million years after the Big Bang. Here’s how we know.
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“It’s important to recognize that there are a wide variety of possible values that dark energy could have, including significantly larger values, that would still lead to a Universe very much like our own. Until we understand where these values come from, and what makes one set of values more likely than another, it’s grossly unfair to claim that we won the cosmic lottery in having a Universe with the values ours possesses. Unless you know the rules that govern the game you’re playing, you have no idea how likely or unlikely the one result you see actually was.”

There are a series of interesting results that have just emerged from the EAGLE collaboration, which has been simulating the Universe to learn what types of stars and galaxies form within it. They varied the value of dark energy in it tremendously, and found that even if you increased the amount by five, ten, or fifty times as much, you’d still form plenty of stars and galaxies: enough to give you chances at life like we have here. This surprised them, since they assumed the value of dark energy we have is finely-tuned to allow life. But it appears that things may not be as finely-tuned as we had thought! The simulation results are interesting, but this doesn’t really tell you anything about aliens in the Multiverse, since we have no idea what causes dark energy to have the values that it does.

Until we know the rules that govern this, we can’t really say what dark energy tells us about aliens in Universes other than our own. Here’s why.
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