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Shared Circles including Ethan Siegel

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Activity

Average numbers for the latest posts (max. 50 posts, posted within the last 4 weeks)

10
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9
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Top posts in the last 50 posts

Most comments: 48

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2015-07-18 21:49:08 (48 comments, 5 reshares, 43 +1s)Open 

"[I]n the solar system, AFAIK, there is no single “moon of a moon”, something like an asteroid orbiting the moon of a planet. Is there a reason for that (like such an orbit being unstable)? Or is it just unlikely to occur?"

In the solar system, everything orbits the Sun: planets, asteroids, kuiper belt objects and more. That is, unless an object is in orbit around one of those, like a moon or a satellite object. Is it possible, then, for a moon or satellite to have another level: an object that orbits it, in turn? While we presently haven't discovered any in our Solar System, it is theoretically possible, with numerous candidates already identified for where to look for such objects.

Most reshares: 36

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2015-06-22 14:08:52 (8 comments, 36 reshares, 70 +1s)Open 

"So even though most particles in the Sun don’t have enough energy to get us there, it would only take a tiny percentage fusing together to power the Sun as we see it. So we do our calculations, we calculate how the protons in the Sun’s core have their energy distributed, and we come up with a number for these proton-proton collisions with sufficient energy to undergo nuclear fusion.

That number is exactly zero."

The Sun consists of some 10^57 particles, nearly 10% of which are in the core, which ranges from 4-15 million K, hot enough for nuclear fusion to occur. A whopping 4 × 10^38 protons fuse into helium-4 every second, and due to the temperatures and densities inside, the raw protons undergo billions of collisions during that time. Yet none of those collisions have a sufficient energy to overcome the Coulomb barrier; it's only through the power of quantummech... more »

Most plusones: 128

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2015-06-22 13:07:52 (4 comments, 18 reshares, 128 +1s)Open 

“But in order to form these new stars, and to drive the density waves that give galaxies their spiral shapes, galaxies require a “skeleton” of neutral, light-blocking atoms and molecules to underlie it all.”

While other galaxies tended to have high-density dust – infrared dark clouds – tracing out the backbones of their spiral arms, none had ever been discovered in the Milky Way. Until, that is, one of these “skeletal” features was discovered using the Spitzer Space Telescope in 2010. Recently, that “bone” was discovered to be even longer than suspected, and may be the central feature of the Scutum-Centaurus arm, the closest major spiral arm to the Sun.

Latest 50 posts

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2015-07-29 01:06:38 (3 comments, 4 reshares, 18 +1s)Open 

“6. It’s responsible for the structures in the universe.

Since dark matter doesn’t interact much with itself and other stuff, it’s the first type of matter to settle down when the universe expands and the first to form structures under its own gravitational pull. It is dark matter that seeds the filaments along which galaxies later form when visible matter falls into the gravitational potential created by the dark matter. If you look at some computer simulation of structure formation, what is shown is almost always the distribution of dark matter, not of visible matter. Visible matter falls into, and hence, is assumed to follow the same distribution at later times.”

When it comes to dark matter, the mysterious substance that makes up the vast majority of the mass in the Universe, there's a whole lot we don't understand or know about it. You might think that there areso many u... more »

“6. It’s responsible for the structures in the universe.

Since dark matter doesn’t interact much with itself and other stuff, it’s the first type of matter to settle down when the universe expands and the first to form structures under its own gravitational pull. It is dark matter that seeds the filaments along which galaxies later form when visible matter falls into the gravitational potential created by the dark matter. If you look at some computer simulation of structure formation, what is shown is almost always the distribution of dark matter, not of visible matter. Visible matter falls into, and hence, is assumed to follow the same distribution at later times.”

When it comes to dark matter, the mysterious substance that makes up the vast majority of the mass in the Universe, there's a whole lot we don't understand or know about it. You might think that there are so many unknowns that are so huge that -- quite reasonably -- perhaps it doesn't exist at all, and there's some other explanation for the behavior of masses on galactic scales and up? And yet, you can't make that leap unless you've honestly (and scientifically) considered the full suite of evidence and facts that speak to the question of dark matter's existence. Sabine Hossenfelder does exactly that.___

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2015-07-28 20:45:09 (2 comments, 2 reshares, 29 +1s)Open 

"Grand design spirals (which make up only about 10% of galaxies) tend to have 2 or 4 strong spiral arms, and they’re often extremely photogenic and pleasingly symmetric objects in the sky. But the method of forming and maintaining those arms has been remarkably hard to explain.

The problem with explaining spiral arms lies fundamentally in that the components of a galaxy rotate at different speeds; the inner part of the galaxy rotates faster than the outer parts. So the easiest explanation — that the arms are actually just areas of the galaxy that are physically more dense, and a fixed association — doesn’t work."

Most mental images of galaxies invoke thoughts of two giant arms, spiraling out from the center and wrapping around, covered richly in stars. Yet this picture, though incredibly common, represents only about 10% of galaxies. Moreover, the galaxiesthat do have tw... more »

"Grand design spirals (which make up only about 10% of galaxies) tend to have 2 or 4 strong spiral arms, and they’re often extremely photogenic and pleasingly symmetric objects in the sky. But the method of forming and maintaining those arms has been remarkably hard to explain.

The problem with explaining spiral arms lies fundamentally in that the components of a galaxy rotate at different speeds; the inner part of the galaxy rotates faster than the outer parts. So the easiest explanation — that the arms are actually just areas of the galaxy that are physically more dense, and a fixed association — doesn’t work."

Most mental images of galaxies invoke thoughts of two giant arms, spiraling out from the center and wrapping around, covered richly in stars. Yet this picture, though incredibly common, represents only about 10% of galaxies. Moreover, the galaxies that do have two grand, spiral arms won't have them for very long, as the classic picture we have of spirals represents only an intermediate stage in galaxy evolution.___

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2015-07-27 13:58:33 (1 comments, 6 reshares, 29 +1s)Open 

“Ultraviolet images from Swift and GALEX showcase the hottest, youngest, bluest stars, which are found in clusters along the spiral arms and in the very center. In the infrared, from WISE and Spitzer, the cool gas shows where future generations of stars will form next. The shorter infrared wavelengths also highlight stars irrespective of whether galactic dust obscures them or not.”

If we want to know where new stars have formed, where the hottest ones are, where new ones will be forming and what lies behind the dust, we have to look in wavelengths beyond what our eyes can see. Yet our greatest space observatories can do exactly this, at both longer and shorter wavelengths, revealing a whole galaxy’s worth of secrets!

“Ultraviolet images from Swift and GALEX showcase the hottest, youngest, bluest stars, which are found in clusters along the spiral arms and in the very center. In the infrared, from WISE and Spitzer, the cool gas shows where future generations of stars will form next. The shorter infrared wavelengths also highlight stars irrespective of whether galactic dust obscures them or not.”

If we want to know where new stars have formed, where the hottest ones are, where new ones will be forming and what lies behind the dust, we have to look in wavelengths beyond what our eyes can see. Yet our greatest space observatories can do exactly this, at both longer and shorter wavelengths, revealing a whole galaxy’s worth of secrets!___

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2015-07-26 18:54:37 (0 comments, 0 reshares, 6 +1s)Open 

"During the day hours, a series of images from the specific location are shown on the display. We replace the missing background and create a magic dimensional window. A dynamic motion parallax effect occurs as the vehicle passes the location."

"Unvertising" artist Brian Kane is turning ClearChannel billboards into visual simulations of the lost, missing natural world. His project, Healing Tool, showcases the nature that would be present if the billboard (and urbanization) were absent. And you've got to see what it looks like at night!

"During the day hours, a series of images from the specific location are shown on the display. We replace the missing background and create a magic dimensional window. A dynamic motion parallax effect occurs as the vehicle passes the location."

"Unvertising" artist Brian Kane is turning ClearChannel billboards into visual simulations of the lost, missing natural world. His project, Healing Tool, showcases the nature that would be present if the billboard (and urbanization) were absent. And you've got to see what it looks like at night!___

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2015-07-25 14:52:40 (4 comments, 3 reshares, 27 +1s)Open 

"[T]here are pros and cons to Earth-sized planets orbiting in the habitable zones of M-stars. The pros are easy: M-stars are more numerous, they’re less likely to have giant worlds in there, they’re longer lived that the Sun, they’re more stable in luminosity over time than the Sun, they give off less ionizing radiation, and their planets are in closer orbit and thus better protected from chance encounters originating from interplanetary or interstellar space.

But the cons are rough:

* more frequent and nastier solar flares,
* less energy available from starlight/sunlight for spurring life processes,
* and tidal locking is a much greater danger at such close distances."

Are Sun-like stars the best place to look for Earth-like worlds?
Is asteroid mining for real?
How do we know that pentaquarks are really bound states of five things, andnot a... more »

"[T]here are pros and cons to Earth-sized planets orbiting in the habitable zones of M-stars. The pros are easy: M-stars are more numerous, they’re less likely to have giant worlds in there, they’re longer lived that the Sun, they’re more stable in luminosity over time than the Sun, they give off less ionizing radiation, and their planets are in closer orbit and thus better protected from chance encounters originating from interplanetary or interstellar space.

But the cons are rough:

* more frequent and nastier solar flares,
* less energy available from starlight/sunlight for spurring life processes,
* and tidal locking is a much greater danger at such close distances."

Are Sun-like stars the best place to look for Earth-like worlds?
Is asteroid mining for real?
How do we know that pentaquarks are really bound states of five things, and not a meson and a baryon just found together?
Check these (and more) out on our comments of the week!___

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2015-07-25 14:13:27 (2 comments, 14 reshares, 66 +1s)Open 

"Even outer to Iapetus lies Phoebe, a smaller moon that’s most likely a captured object from the Kuiper belt. Unlike all of Saturn’s other moons, Phoebe orbits in the opposite direction, is far more distant, and most importantly, is very, very dark. In addition, Phoebe has been emitting a steady stream of particles for a very long time, as the Sun’s radiation and minor collisions are strong enough to kick dust grains off of Phoebe’s loosely-held-together surface."

When Giovanni Cassini discovered Saturn's moon Iapetus in 1671, he was puzzled to find that it was easily visible on the western side of the planet, but unable to be seen along the eastern side. Only 34 years later did he find it on the east side, finding it two full magnitudes dimmer. His theory was that Iapetus was locked to Saturn, and that it had one light hemisphere and one dark one. It took another 300 years,but now... more »

"Even outer to Iapetus lies Phoebe, a smaller moon that’s most likely a captured object from the Kuiper belt. Unlike all of Saturn’s other moons, Phoebe orbits in the opposite direction, is far more distant, and most importantly, is very, very dark. In addition, Phoebe has been emitting a steady stream of particles for a very long time, as the Sun’s radiation and minor collisions are strong enough to kick dust grains off of Phoebe’s loosely-held-together surface."

When Giovanni Cassini discovered Saturn's moon Iapetus in 1671, he was puzzled to find that it was easily visible on the western side of the planet, but unable to be seen along the eastern side. Only 34 years later did he find it on the east side, finding it two full magnitudes dimmer. His theory was that Iapetus was locked to Saturn, and that it had one light hemisphere and one dark one. It took another 300 years, but now we finally know what caused this two-toned world: a captured Kuiper belt object is to blame!___

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2015-07-24 22:16:55 (1 comments, 5 reshares, 22 +1s)Open 

"How long would it take for stars to cool down after they have exhausted their nuclear fuel? Will there be any ‘black’ dwarfs? Are there any today?"

While the stars exist in tremendous numbers (some 10^23+ in our observable Universe) and great varieties, every star that ever has shone or will shine will someday run out of fuel and die. When that happens, the inner core of the star contracts down to form a tiny, degenerate but very hot object. But even so, no object with a finite amount of energy can shine forever. At some point, even those stellar remnants will cool down out of the visible portion of the spectrum. But how long will that take, how will that happen, and has the Universe been around long enough (yet) so that such an object exists? Answers here.

"How long would it take for stars to cool down after they have exhausted their nuclear fuel? Will there be any ‘black’ dwarfs? Are there any today?"

While the stars exist in tremendous numbers (some 10^23+ in our observable Universe) and great varieties, every star that ever has shone or will shine will someday run out of fuel and die. When that happens, the inner core of the star contracts down to form a tiny, degenerate but very hot object. But even so, no object with a finite amount of energy can shine forever. At some point, even those stellar remnants will cool down out of the visible portion of the spectrum. But how long will that take, how will that happen, and has the Universe been around long enough (yet) so that such an object exists? Answers here.___

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2015-07-23 22:42:21 (23 comments, 8 reshares, 28 +1s)Open 

"The key in all of this — and the point you should take away — is that finding a “twin” of Earth isn’t the holy grail it’s touted to be. It’s that if we want to find that which we most desire, to find a world that has the same secrets that ours has, the key is not to look for an identical twin, or at least to not limit ourselves to looking for identical twins. Rather, it’s to look for the full suite of the right conditions, and to realize that while they do occur on identical twins, that isn’t the most common place to find them."

Earlier today, NASA announced the most Earth-like exoplanet yet, a planet just 60% larger in radius than our own, orbiting a star of the same spectral class as our Sun and with an almost identical orbital period: 385 days. But is this really the most Earth-like planet we’ve discovered? It’s significantly larger and five times asmassive, and may actually be ... more »

"The key in all of this — and the point you should take away — is that finding a “twin” of Earth isn’t the holy grail it’s touted to be. It’s that if we want to find that which we most desire, to find a world that has the same secrets that ours has, the key is not to look for an identical twin, or at least to not limit ourselves to looking for identical twins. Rather, it’s to look for the full suite of the right conditions, and to realize that while they do occur on identical twins, that isn’t the most common place to find them."

Earlier today, NASA announced the most Earth-like exoplanet yet, a planet just 60% larger in radius than our own, orbiting a star of the same spectral class as our Sun and with an almost identical orbital period: 385 days. But is this really the most Earth-like planet we’ve discovered? It’s significantly larger and five times as massive, and may actually be more like Neptune than like Earth. In fact, other properties may be much more important if we truly want to find a “twin” to Earth: a rocky planet teeming with advanced chemical-based life.___

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2015-07-23 01:06:51 (5 comments, 20 reshares, 51 +1s)Open 

"The amazing thing about pentaquarks and all sorts of exotic states of matter isn’t that they exist, but that they enable us to push the limits of physics even farther, and to probe the boundaries of our most sacred theoretical predictions. The most exciting utterance we can make in physics is, “that’s funny,” as Rutherford must’ve thought to himself more than a century ago. Every time we push the frontiers like this, we create a new opportunity for ourselves to find out whether nature’s in line with our expectations, or whether there really is something funny there."

Over 100 years ago, Rutherford's gold foil experiment discovered the atomic nucleus. At higher energies, we can split that nucleus apart into protons and neutrons, and at still higher ones, into individual quarks and gluons. But these quarks and gluons can combine in amazing ways: not just into mesons andbaryons, bu... more »

"The amazing thing about pentaquarks and all sorts of exotic states of matter isn’t that they exist, but that they enable us to push the limits of physics even farther, and to probe the boundaries of our most sacred theoretical predictions. The most exciting utterance we can make in physics is, “that’s funny,” as Rutherford must’ve thought to himself more than a century ago. Every time we push the frontiers like this, we create a new opportunity for ourselves to find out whether nature’s in line with our expectations, or whether there really is something funny there."

Over 100 years ago, Rutherford's gold foil experiment discovered the atomic nucleus. At higher energies, we can split that nucleus apart into protons and neutrons, and at still higher ones, into individual quarks and gluons. But these quarks and gluons can combine in amazing ways: not just into mesons and baryons, but into exotic states like tetraquarks, pentaquarks and even glueballs. As the LHC brings these states from theory to reality, here's what we're poised to learn, and probe, by pushing the limits of quantum chromodynamics.___

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2015-07-22 01:06:49 (0 comments, 1 reshares, 15 +1s)Open 

"While it was amazing to see some of Chile’s best observatories, what I really gained from the experience was how much modern astronomy is a human endeavor. While we often talk about breakthrough discoveries, or the amazing engineering of modern observatories, much of the work is done behind the scenes. "

It's paradoxical how our eyes work: we adjust to the brightness of everything around us. A modestly illuminated night sky will leave just a few dozen stars and planets visible, while if you take that light pollution away, thousands of stars, the Milky Way and even galaxies can be seen with the naked eye alone. Perhaps surprisingly, there's a country out there with high mountains, dark skies, and great seeing that values astronomy: Chile. A great report from astrophysicist +Brian Koberlein as he forays into observational astronomy and voyages to Chile to find outfi... more »

"While it was amazing to see some of Chile’s best observatories, what I really gained from the experience was how much modern astronomy is a human endeavor. While we often talk about breakthrough discoveries, or the amazing engineering of modern observatories, much of the work is done behind the scenes. "

It's paradoxical how our eyes work: we adjust to the brightness of everything around us. A modestly illuminated night sky will leave just a few dozen stars and planets visible, while if you take that light pollution away, thousands of stars, the Milky Way and even galaxies can be seen with the naked eye alone. Perhaps surprisingly, there's a country out there with high mountains, dark skies, and great seeing that values astronomy: Chile. A great report from astrophysicist +Brian Koberlein as he forays into observational astronomy and voyages to Chile to find out firsthand!___

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2015-07-20 14:33:39 (1 comments, 1 reshares, 12 +1s)Open 

“In the full-resolution images displayed here, the points of light displaying the pointy “diffraction spikes” are stars within our own Milky Way, while everything else is a galaxy unto itself. The galaxies appearing largest are not simply larger but are only closer in proximity to us, with the most distant galaxies here nearly 30 billion light years distant from us at present. The light from the most distant galaxies observed here has been traveling for over 13 billion years, and appears redder in color thanks to the expansion of the Universe.”

What do we see if we take an area almost a third the size of the full Moon – far larger than any of the Hubble deep fields – and view it from the ultraviolet through the visible and into the infrared, capable of seeing objects 250,000,000 times fainter than our naked eye can see? Come find out, in full resolution, on Mostly Mute Monday.

“In the full-resolution images displayed here, the points of light displaying the pointy “diffraction spikes” are stars within our own Milky Way, while everything else is a galaxy unto itself. The galaxies appearing largest are not simply larger but are only closer in proximity to us, with the most distant galaxies here nearly 30 billion light years distant from us at present. The light from the most distant galaxies observed here has been traveling for over 13 billion years, and appears redder in color thanks to the expansion of the Universe.”

What do we see if we take an area almost a third the size of the full Moon – far larger than any of the Hubble deep fields – and view it from the ultraviolet through the visible and into the infrared, capable of seeing objects 250,000,000 times fainter than our naked eye can see? Come find out, in full resolution, on Mostly Mute Monday.___

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2015-07-19 20:31:16 (28 comments, 16 reshares, 72 +1s)Open 

"The most precious elements we find on Earth aren’t necessarily the ones that have the greatest variety of uses, the most beautiful, or that enable the most effective solutions to a problem. Rather, they’re the ones that are indispensable for any particular application.

As it turns out, this is the case for practically all elements: there are applications each element is uniquely suited for, and no other element has the same exact properties. The most precious elements of all, therefore, are the rarest ones that we can put to use."

For each pure element, there’s an abundance in our Solar System that’s relatively consistent across where we look, with only the gravitational gradient in our Solar System’s formation responsible for the differences. However, our Earth is huge and differentiated, and even our richest mines pale in comparison to another location: justbeneath t... more »

"The most precious elements we find on Earth aren’t necessarily the ones that have the greatest variety of uses, the most beautiful, or that enable the most effective solutions to a problem. Rather, they’re the ones that are indispensable for any particular application.

As it turns out, this is the case for practically all elements: there are applications each element is uniquely suited for, and no other element has the same exact properties. The most precious elements of all, therefore, are the rarest ones that we can put to use."

For each pure element, there’s an abundance in our Solar System that’s relatively consistent across where we look, with only the gravitational gradient in our Solar System’s formation responsible for the differences. However, our Earth is huge and differentiated, and even our richest mines pale in comparison to another location: just beneath the surface of asteroids. Could asteroid mining pave the way to riches from space in our future?___

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2015-07-19 14:42:35 (23 comments, 16 reshares, 75 +1s)Open 

"The Sun as it exists today, 4.5 billion years after the creation of the Solar System, is about 20% more energetic than it was at the earliest times. If it weren’t for the greenhouse effect of our atmosphere, early Earth would have been as frozen as Mars is today. But as time goes on, the Sun will continue to heat up."

If it's weren't for our atmosphere at all, the average temperature on Earth's surface would be a paltry 255 kelvin (-18 C / 0 F), so the greenhouse effect does plenty of good by warming us an additional 33 C (59 F) on average. But over timescales of hundreds of millions of years, the Sun's energy output increases as its core temperature — and the rate of fusion — heats up. In one-to-two billion years, the Earth's oceans will boil, ending life as we know it on our world. Perhaps we're very lucky life evolved as fast as it did on Earth; alittl... more »

"The Sun as it exists today, 4.5 billion years after the creation of the Solar System, is about 20% more energetic than it was at the earliest times. If it weren’t for the greenhouse effect of our atmosphere, early Earth would have been as frozen as Mars is today. But as time goes on, the Sun will continue to heat up."

If it's weren't for our atmosphere at all, the average temperature on Earth's surface would be a paltry 255 kelvin (-18 C / 0 F), so the greenhouse effect does plenty of good by warming us an additional 33 C (59 F) on average. But over timescales of hundreds of millions of years, the Sun's energy output increases as its core temperature — and the rate of fusion — heats up. In one-to-two billion years, the Earth's oceans will boil, ending life as we know it on our world. Perhaps we're very lucky life evolved as fast as it did on Earth; a little slower and intelligent life may never have had a chance.___

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2015-07-19 01:58:41 (19 comments, 6 reshares, 31 +1s)Open 

“Outside of our observable Universe, beyond what is causally connected to us, past any interactions, we come to this inflationary multiverse. The only way to test it involves destroying our Universe as we know it, not a pretty thought. It’s metaphysics — literally “after” physics — in the sense that physics leads you there. And this is a feature that I like. It isn’t idle speculation, it’s an inevitable consequence of our best theory, if our best theory is right all the way down.”

Beyond the limit of physics, there’s the consequences of our best physical theories, but that are in principle unobservable. That doesn’t mean they’re not interesting, but it does mean they aren’t science. This, plus Pluto, stars, and actually experiencing things live on our comments of the week!

“Outside of our observable Universe, beyond what is causally connected to us, past any interactions, we come to this inflationary multiverse. The only way to test it involves destroying our Universe as we know it, not a pretty thought. It’s metaphysics — literally “after” physics — in the sense that physics leads you there. And this is a feature that I like. It isn’t idle speculation, it’s an inevitable consequence of our best theory, if our best theory is right all the way down.”

Beyond the limit of physics, there’s the consequences of our best physical theories, but that are in principle unobservable. That doesn’t mean they’re not interesting, but it does mean they aren’t science. This, plus Pluto, stars, and actually experiencing things live on our comments of the week!___

posted image

2015-07-18 21:49:08 (48 comments, 5 reshares, 43 +1s)Open 

"[I]n the solar system, AFAIK, there is no single “moon of a moon”, something like an asteroid orbiting the moon of a planet. Is there a reason for that (like such an orbit being unstable)? Or is it just unlikely to occur?"

In the solar system, everything orbits the Sun: planets, asteroids, kuiper belt objects and more. That is, unless an object is in orbit around one of those, like a moon or a satellite object. Is it possible, then, for a moon or satellite to have another level: an object that orbits it, in turn? While we presently haven't discovered any in our Solar System, it is theoretically possible, with numerous candidates already identified for where to look for such objects.

"[I]n the solar system, AFAIK, there is no single “moon of a moon”, something like an asteroid orbiting the moon of a planet. Is there a reason for that (like such an orbit being unstable)? Or is it just unlikely to occur?"

In the solar system, everything orbits the Sun: planets, asteroids, kuiper belt objects and more. That is, unless an object is in orbit around one of those, like a moon or a satellite object. Is it possible, then, for a moon or satellite to have another level: an object that orbits it, in turn? While we presently haven't discovered any in our Solar System, it is theoretically possible, with numerous candidates already identified for where to look for such objects.___

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2015-07-17 00:44:24 (5 comments, 8 reshares, 31 +1s)Open 

"This is why a star whose temperature might be half that of the Sun can live hundreds of times as long, and an incredibly hot star — like R136a1 (at the core of the cluster below), with 260 times the mass of the Sun — will live less than 0.1% as long as our Sun."

If you ever wondered how stars lived, died, and transitioned through their life cycle, this is where the answers you've been seeking are.

"This is why a star whose temperature might be half that of the Sun can live hundreds of times as long, and an incredibly hot star — like R136a1 (at the core of the cluster below), with 260 times the mass of the Sun — will live less than 0.1% as long as our Sun."

If you ever wondered how stars lived, died, and transitioned through their life cycle, this is where the answers you've been seeking are.___

posted image

2015-07-15 18:05:52 (0 comments, 5 reshares, 15 +1s)Open 

"2. Why is it interesting that our universe might be a hologram?

This limitation on the amount of independence between particles due to holography would only become noticeable at densities too high for us to test directly. The reason this type of duality is interesting nevertheless is that physics is mostly the art of skillful approximation, and using dualities is a new skill."

When it comes to the fabric of our Universe, we live in four dimensions: three space and one time. At least, that’s what it seems like. But it’s possible that at very high energy scales — or at very small distance scales — not only might even more forces unify, but we might discover that the interactions between particles spill over into even more spatial dimensions. Through concepts like unification, duality and holography, we're starting to understand exactly what might be relevant forour Uni... more »

"2. Why is it interesting that our universe might be a hologram?

This limitation on the amount of independence between particles due to holography would only become noticeable at densities too high for us to test directly. The reason this type of duality is interesting nevertheless is that physics is mostly the art of skillful approximation, and using dualities is a new skill."

When it comes to the fabric of our Universe, we live in four dimensions: three space and one time. At least, that’s what it seems like. But it’s possible that at very high energy scales — or at very small distance scales — not only might even more forces unify, but we might discover that the interactions between particles spill over into even more spatial dimensions. Through concepts like unification, duality and holography, we're starting to understand exactly what might be relevant for our Universe, and what might be forever beyond our reach.___

posted image

2015-07-15 00:44:28 (20 comments, 11 reshares, 61 +1s)Open 

"While the data transfer back is incredibly slow — not only does it take over four hours for the light to travel, but the data rate is terribly slow at just 1/8th of a kilobyte per second at such a great distance — we now have unprecedented views and data on Pluto and its neighboring worlds. We’ve discovered surface geology, incredible features, colors and atmospheric properties.

At last, Pluto is no longer a “dot” in the sky, but its own world with its own unique cosmic story."

Pluto and all the other Pluto-like objects out there in the Kuiper belt are not only paramount to the formation of our own Solar System, these objects vastly outnumber the planets. Not only our Solar System’s planets, but the icy, lonesome Kuiper belt objects outnumber the planets galaxy-wide. With everything we’re learning about it, is it time to reinstate Pluto’splanethood?... more »

"While the data transfer back is incredibly slow — not only does it take over four hours for the light to travel, but the data rate is terribly slow at just 1/8th of a kilobyte per second at such a great distance — we now have unprecedented views and data on Pluto and its neighboring worlds. We’ve discovered surface geology, incredible features, colors and atmospheric properties.

At last, Pluto is no longer a “dot” in the sky, but its own world with its own unique cosmic story."

Pluto and all the other Pluto-like objects out there in the Kuiper belt are not only paramount to the formation of our own Solar System, these objects vastly outnumber the planets. Not only our Solar System’s planets, but the icy, lonesome Kuiper belt objects outnumber the planets galaxy-wide. With everything we’re learning about it, is it time to reinstate Pluto’s planethood?___

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2015-07-14 17:53:12 (8 comments, 25 reshares, 40 +1s)Open 

"Sure, we can return these images and view them what seems like immediately. What you might not realize, however, is just how mind-bogglingly long it takes to get this data from Pluto back to Earth. While it’s true that a photon is a photon, to catch and collect a photon from such a great distance away is a truly incredible feat. Light spreads out over distance, and at three billion miles away, it takes a seventy-meter diameter telescope to capture the faint, diffuse signal arriving on Earth from New Horizons. Even with a telescope that large, it can only collect 125 bytes of data per second."

The speed of light requires a little over four hours to send a signal from Pluto to Earth. With NASA's New Horizons having just completed its flyby the morning of July 14th, you might think that it's only a short matter of time before we have everything it has to offer. But in reality,w... more »

"Sure, we can return these images and view them what seems like immediately. What you might not realize, however, is just how mind-bogglingly long it takes to get this data from Pluto back to Earth. While it’s true that a photon is a photon, to catch and collect a photon from such a great distance away is a truly incredible feat. Light spreads out over distance, and at three billion miles away, it takes a seventy-meter diameter telescope to capture the faint, diffuse signal arriving on Earth from New Horizons. Even with a telescope that large, it can only collect 125 bytes of data per second."

The speed of light requires a little over four hours to send a signal from Pluto to Earth. With NASA's New Horizons having just completed its flyby the morning of July 14th, you might think that it's only a short matter of time before we have everything it has to offer. But in reality, when it begins data transmission, it will take a full 16 months to transfer the full suite of its data to us. Here's the science of why.___

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2015-07-13 13:55:11 (2 comments, 16 reshares, 73 +1s)Open 

“In visible light, there are cloudy regions — nebulae — in space that appear a bright blue color. But this isn’t gas that’s actually blue, but rather neutral, dusty material that’s reflecting the bright blue light from nearby, newly formed stars. These reflection nebulae are always blue in color, and are found alongside bright, young star clusters.”

But there's much more to these reflection nebulae than their color, there's also some amazing astrophysics at play, something we reveal when we look in infrared light and also at the dust lanes that obscure our view. Come find out the full story and see the full suite of spectacular images on Mostly Mute Monday!

“In visible light, there are cloudy regions — nebulae — in space that appear a bright blue color. But this isn’t gas that’s actually blue, but rather neutral, dusty material that’s reflecting the bright blue light from nearby, newly formed stars. These reflection nebulae are always blue in color, and are found alongside bright, young star clusters.”

But there's much more to these reflection nebulae than their color, there's also some amazing astrophysics at play, something we reveal when we look in infrared light and also at the dust lanes that obscure our view. Come find out the full story and see the full suite of spectacular images on Mostly Mute Monday!___

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2015-07-12 21:34:33 (0 comments, 1 reshares, 10 +1s)Open 

"And when they played this song again… I totally lost it. They not only were the most memorable musical act of the whole festival for me, they totally opened me up to a style of music I don’t normally even listen to."

If you're at all a music fan, and you enjoy discovering new acts of different genres, you might appreciate these six new (to me) finds from last week's High Sierra Music Festival. You might even discover a new must-see musical act for yourself.

"And when they played this song again… I totally lost it. They not only were the most memorable musical act of the whole festival for me, they totally opened me up to a style of music I don’t normally even listen to."

If you're at all a music fan, and you enjoy discovering new acts of different genres, you might appreciate these six new (to me) finds from last week's High Sierra Music Festival. You might even discover a new must-see musical act for yourself.___

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2015-07-11 16:02:35 (5 comments, 2 reshares, 36 +1s)Open 

"You’ll read headlines all the time today about “such-and-such baffles astronomers” or “defies cosmic expectations” or “object that shouldn’t exist,” and it’s all absolute sensationalist rubbish. We have a range of uncertainty on what we know, and all the observations fall within that range. The biggest surprise we’ve gotten (or are ever likely to get) are in the cases where we’ve dishonestly fooled ourselves about how large or small the uncertainties truly are."

Some things we know and others we don't, but the most important thing we can do is be honest about our confidence levels and open about our reasons for them. Why? So we can not only challenge them properly, but move forward by probing the limits beyond our current theories. Find out more about dark matter, large-scale structure and our solar system on this edition of comments of the week!

"You’ll read headlines all the time today about “such-and-such baffles astronomers” or “defies cosmic expectations” or “object that shouldn’t exist,” and it’s all absolute sensationalist rubbish. We have a range of uncertainty on what we know, and all the observations fall within that range. The biggest surprise we’ve gotten (or are ever likely to get) are in the cases where we’ve dishonestly fooled ourselves about how large or small the uncertainties truly are."

Some things we know and others we don't, but the most important thing we can do is be honest about our confidence levels and open about our reasons for them. Why? So we can not only challenge them properly, but move forward by probing the limits beyond our current theories. Find out more about dark matter, large-scale structure and our solar system on this edition of comments of the week!___

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2015-07-11 15:45:01 (28 comments, 17 reshares, 64 +1s)Open 

"[T]here’s a whole class of worlds in between the size of Earth and Neptune, called either super-Earths or mini-Neptunes, where a rocky core is surrounded by a hydrogen-and-helium envelope of gas. This class not only exists, but it’s the most common type of planet in the Universe, to the best of our knowledge.

So why don’t we have even one in our Solar System?

Believe it or not, the chances are very good that we did. Once."

What happened to our Solar System that we don't anymore? Come and find out on my latest for Forbes!

"[T]here’s a whole class of worlds in between the size of Earth and Neptune, called either super-Earths or mini-Neptunes, where a rocky core is surrounded by a hydrogen-and-helium envelope of gas. This class not only exists, but it’s the most common type of planet in the Universe, to the best of our knowledge.

So why don’t we have even one in our Solar System?

Believe it or not, the chances are very good that we did. Once."

What happened to our Solar System that we don't anymore? Come and find out on my latest for Forbes!___

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2015-07-10 22:11:12 (23 comments, 15 reshares, 34 +1s)Open 

"The thing is, the Multiverse is not a scientific theory on its own. Rather, it’s a theoretical consequence of the laws of physics as they’re best understood today. It’s perhaps even an inevitable consequence of those laws: if you have an inflationary Universe governed by quantum physics, this is something you’re pretty much bound to wind up with.

But the Multiverse isn’t necessary to explain anything about the Universe we live in. It solves none of the outstanding problems that we presently have. (And if you say things like “landscape,” “vacuum energy,” “anthropic principle” and “cosmological constant,” you don’t understand what “solve” means.) And worst off, it makes no concrete predictions for something we can necessarily observe."

A scientific theory needs to meet three criteria: it needs to explain all the successes of the previous leadingtheory, it needs to explain any... more »

"The thing is, the Multiverse is not a scientific theory on its own. Rather, it’s a theoretical consequence of the laws of physics as they’re best understood today. It’s perhaps even an inevitable consequence of those laws: if you have an inflationary Universe governed by quantum physics, this is something you’re pretty much bound to wind up with.

But the Multiverse isn’t necessary to explain anything about the Universe we live in. It solves none of the outstanding problems that we presently have. (And if you say things like “landscape,” “vacuum energy,” “anthropic principle” and “cosmological constant,” you don’t understand what “solve” means.) And worst off, it makes no concrete predictions for something we can necessarily observe."

A scientific theory needs to meet three criteria: it needs to explain all the successes of the previous leading theory, it needs to explain any failures or shortcomings that its predecessor couldn't, and it needs to make new, testable predictions that can either be falsified or verified. If the Multiverse doesn't meet that third criterion, can it be considered science? A fascinating exploration leads us to conclude that no, perhaps it isn't science after all.___

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2015-07-10 02:30:51 (2 comments, 6 reshares, 37 +1s)Open 

"Quiz #1: You’re given eight images in random order, one each of a portion of each of the eight planets. The images are all in true color, where available, or altered to be as close to true color as I can make them. Let’s get right to it, and see if you can match all eight!

Quiz #2: Here are three candidate images for each of the eight worlds: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. In each case one image is of the planet in question; the other two are red herrings. Can you pick the right one?"

Naming the planets in order and recognizing what they look like from their famous images might seem like an easy task. But an unfamiliar view, a focus on a single feature or a comparison with two similar images from other worlds can prove an incredibly difficult task. Take these two planet identification quizzes and see for yourself; the Solar System maybe ... more »

"Quiz #1: You’re given eight images in random order, one each of a portion of each of the eight planets. The images are all in true color, where available, or altered to be as close to true color as I can make them. Let’s get right to it, and see if you can match all eight!

Quiz #2: Here are three candidate images for each of the eight worlds: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. In each case one image is of the planet in question; the other two are red herrings. Can you pick the right one?"

Naming the planets in order and recognizing what they look like from their famous images might seem like an easy task. But an unfamiliar view, a focus on a single feature or a comparison with two similar images from other worlds can prove an incredibly difficult task. Take these two planet identification quizzes and see for yourself; the Solar System may be incredibly diverse, but the eight planets are often awfully hard to tell apart!___

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2015-07-08 21:00:33 (2 comments, 15 reshares, 55 +1s)Open 

"What are the big white things in Titan’s lakes?

So Titan’s lakes are mostly hydrocarbons: methane and ethane. We notice that these white spots in them appear to change with the seasons. Why? The leading suspicion is that they are either changes in the “water level” of the hydrocarbon lakes themselves, causing features to be revealed or submerged, or that these are floating-and-sinking iceberg features, where of course “water” and “ice” refers to methane, not H2O.

The first explanation is dubious, since the shoreline doesn’t appear to change much. So in addition to the ice features, they could be bubbles, surface waves, or other floating (or barely sub-surface) solids. We’d love to know more; this one really is still a mystery."

On Monday, xkcd asked 36 solar system questions, providing brief answers (and non-answers) to a few of them. But notonly do most of the... more »

"What are the big white things in Titan’s lakes?

So Titan’s lakes are mostly hydrocarbons: methane and ethane. We notice that these white spots in them appear to change with the seasons. Why? The leading suspicion is that they are either changes in the “water level” of the hydrocarbon lakes themselves, causing features to be revealed or submerged, or that these are floating-and-sinking iceberg features, where of course “water” and “ice” refers to methane, not H2O.

The first explanation is dubious, since the shoreline doesn’t appear to change much. So in addition to the ice features, they could be bubbles, surface waves, or other floating (or barely sub-surface) solids. We’d love to know more; this one really is still a mystery."

On Monday, xkcd asked 36 solar system questions, providing brief answers (and non-answers) to a few of them. But not only do most of them have actual, legitimate scientific answers, most of the ones that don't have had a lot of progress made on them. To the best of science's knowledge, here are the best answers to all 36 of them.___

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2015-07-07 23:16:48 (0 comments, 2 reshares, 23 +1s)Open 

"The only mode, therefore, in which, under such a state of affairs, we could comprehend the voids which our telescopes find in innumerable directions, would be by supposing the distance of the invisible background so immense that no ray from it has yet been able to reach us at all."

Back in the 1820s, Heinrich Olbers put forth his famous paradox: that if the night sky was filled uniformly and infinitely with stars, eventually the human eye should encounter one in any and all directions. Yet the darkness of the night sky clearly showed this was not the case! In modern times, the Big Bang provides a solution to this by showing that there is a finite age to the Universe, and hence a time before which there were no stars. There is a leftover glow, but it’s redshifted into the microwave region, visible as the CMB. And perhaps surprisingly, Poe — writing in 1848 — proposed a very BigBang-... more »

"The only mode, therefore, in which, under such a state of affairs, we could comprehend the voids which our telescopes find in innumerable directions, would be by supposing the distance of the invisible background so immense that no ray from it has yet been able to reach us at all."

Back in the 1820s, Heinrich Olbers put forth his famous paradox: that if the night sky was filled uniformly and infinitely with stars, eventually the human eye should encounter one in any and all directions. Yet the darkness of the night sky clearly showed this was not the case! In modern times, the Big Bang provides a solution to this by showing that there is a finite age to the Universe, and hence a time before which there were no stars. There is a leftover glow, but it’s redshifted into the microwave region, visible as the CMB. And perhaps surprisingly, Poe — writing in 1848 — proposed a very Big Bang-like solution to Olbers’ paradox!___

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2015-07-02 12:34:39 (25 comments, 23 reshares, 62 +1s)Open 

“[C]ould you ever see what we know about the universe being upended that we find a different explanation for the cmb or could something happen to make us think we were wrong and misunderstood the red shifts of galaxies or the Doppler effect and that we actually are in a steady state or static universe?”

If there's one thing you can be certain of when it comes to the fundamental, scientific truths of our Universe, it's this: someday, in the not too distant future, those truths will be superseded by more fundamental ones. And even those, quite likely, won't be the final truths, but just one step further along the line towards our understanding of reality. Does this mean that we've necessarily got it all wrong, and that we might just as well ignore the successes of our best theories so far? Does it mean that all we know about the Universe could easily be upended and replaced,lea... more »

“[C]ould you ever see what we know about the universe being upended that we find a different explanation for the cmb or could something happen to make us think we were wrong and misunderstood the red shifts of galaxies or the Doppler effect and that we actually are in a steady state or static universe?”

If there's one thing you can be certain of when it comes to the fundamental, scientific truths of our Universe, it's this: someday, in the not too distant future, those truths will be superseded by more fundamental ones. And even those, quite likely, won't be the final truths, but just one step further along the line towards our understanding of reality. Does this mean that we've necessarily got it all wrong, and that we might just as well ignore the successes of our best theories so far? Does it mean that all we know about the Universe could easily be upended and replaced, leading to vastly different conclusions to questions like where everything came from? These are exceedingly unlikely, for a myriad of reasons. Instead, this is what the next major scientific revolution will probably look like.___

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2015-07-02 12:13:36 (0 comments, 4 reshares, 12 +1s)Open 

“[T]he simplest explanation is that different elements and compounds have different characteristic emission lines. For example, if you take some sodium and heat it up, it emits a characteristic yellow glow, because of its two very narrow emission lines at 588 and 589 nanometers. (You’re probably familiar with them from sodium street lamps.)

We have a great variety of elements and compounds that emit a great variety of colors! Different compounds of Barium, Sodium, Copper and Strontium can produce colors covering a huge range of the visible spectrum, and the different compounds inserted in the fireworks’ stars are responsible for everything we see.”

There are few things as closely associated with American independence as our willingness and eagerness to celebrate with fiery explosions. I refer, of course, to the unique spectacle of fireworks, first developed nearly a millenniumago hal... more »

“[T]he simplest explanation is that different elements and compounds have different characteristic emission lines. For example, if you take some sodium and heat it up, it emits a characteristic yellow glow, because of its two very narrow emission lines at 588 and 589 nanometers. (You’re probably familiar with them from sodium street lamps.)

We have a great variety of elements and compounds that emit a great variety of colors! Different compounds of Barium, Sodium, Copper and Strontium can produce colors covering a huge range of the visible spectrum, and the different compounds inserted in the fireworks’ stars are responsible for everything we see.”

There are few things as closely associated with American independence as our willingness and eagerness to celebrate with fiery explosions. I refer, of course, to the unique spectacle of fireworks, first developed nearly a millennium ago halfway across the world. But these displays don’t happen by themselves; there’s an intricate art and science required to deliver the shows we all expect. So what’s the science behind fireworks? Here's the physics (and a little chemistry) behind their height, size, shape, color and sound, just in time for July 4th!___

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2015-07-01 14:36:12 (33 comments, 17 reshares, 58 +1s)Open 

"[T]he Universe starts off with hydrogen and helium, all stars produce helium, and then stars over a certain mass threshold produce carbon, nitrogen, oxygen and lots of heavier elements. But carbon was already element #6; what about lithium, beryllium and boron (elements #3, #4 and #5)?"

From helium up through uranium continuously, every element in the periodic table can be found, created by natural processes, somewhere in the Universe. (With many trans-uranic nuclides found as well.) Yet out of all of those, only three of them aren't created in stars: lithium, beryllium and boron. Boron in particular is necessary for life as we know it, as without it, there would be no such things as plants. Here's the cosmic story of the only three heavy elements to exist that aren't made in stars.

"[T]he Universe starts off with hydrogen and helium, all stars produce helium, and then stars over a certain mass threshold produce carbon, nitrogen, oxygen and lots of heavier elements. But carbon was already element #6; what about lithium, beryllium and boron (elements #3, #4 and #5)?"

From helium up through uranium continuously, every element in the periodic table can be found, created by natural processes, somewhere in the Universe. (With many trans-uranic nuclides found as well.) Yet out of all of those, only three of them aren't created in stars: lithium, beryllium and boron. Boron in particular is necessary for life as we know it, as without it, there would be no such things as plants. Here's the cosmic story of the only three heavy elements to exist that aren't made in stars.___

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2015-07-01 12:56:33 (1 comments, 4 reshares, 23 +1s)Open 

“Venus’ upper atmosphere may well turn out to be the most Earth-like environment in the Solar System beyond our own world. In fact, there are speculations that Venus’ upper atmosphere — at these altitudes — may in fact harbor life right now!

If we could bring our own sources of sustainable food, engineer solar panels to harvest the (considerably more intense than on Earth) energy from the Sun while protecting them from the sulfuric acid conditions, we would have everything we need to build our own floating civilization above the surface of Venus.”

When we talk about humans existing on worlds other than Earth, the first choice of a planet to do so on is usually Mars, a world that may have been extremely Earth-like for the first billion years of our Solar System or so. Perhaps, with enough ingenuity and resources, we could terraform it to be more like Earth is today.But the most Earth-... more »

“Venus’ upper atmosphere may well turn out to be the most Earth-like environment in the Solar System beyond our own world. In fact, there are speculations that Venus’ upper atmosphere — at these altitudes — may in fact harbor life right now!

If we could bring our own sources of sustainable food, engineer solar panels to harvest the (considerably more intense than on Earth) energy from the Sun while protecting them from the sulfuric acid conditions, we would have everything we need to build our own floating civilization above the surface of Venus.”

When we talk about humans existing on worlds other than Earth, the first choice of a planet to do so on is usually Mars, a world that may have been extremely Earth-like for the first billion years of our Solar System or so. Perhaps, with enough ingenuity and resources, we could terraform it to be more like Earth is today. But the most Earth-like conditions in the Solar System don't occur on the surface of Mars, but rather in the high altitudes of Venus' atmosphere, some 50-65 km up. Despite its harsh conditions, this may be the best location for the first human colonies, for a myriad of good, scientific reasons.___

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2015-06-30 15:40:01 (14 comments, 17 reshares, 65 +1s)Open 

"Information doesn’t always travel at the speed of light, though — depending on the environment that the information is traveling through, and the form of that information (which is not always light), the speed of information can proceed at speeds that are much slower than the speed of light. The speed of light in a vacuum seems to be a hard upper limit that nothing can surpass, but if your information is in the form of a compression wave, like sound, then the information travels at the speed of sound in that medium."

There’s something puzzling about black holes, if you stop to consider it. On the one hand, they’re objects so massive and dense — compacted into such a small region of space — that nothing can escape from it, not even light. That’s the definition of a black hole, and why “black” is in the name. But gravity also moves at the speed of light, and yet thegravitational influen... more »

"Information doesn’t always travel at the speed of light, though — depending on the environment that the information is traveling through, and the form of that information (which is not always light), the speed of information can proceed at speeds that are much slower than the speed of light. The speed of light in a vacuum seems to be a hard upper limit that nothing can surpass, but if your information is in the form of a compression wave, like sound, then the information travels at the speed of sound in that medium."

There’s something puzzling about black holes, if you stop to consider it. On the one hand, they’re objects so massive and dense — compacted into such a small region of space — that nothing can escape from it, not even light. That’s the definition of a black hole, and why “black” is in the name. But gravity also moves at the speed of light, and yet the gravitational influence of a black hole has absolutely no problem extending not only beyond the event horizon, but infinite distances out into the abyss of space. Jillian Scudder has the answer to this puzzling conundrum!___

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2015-06-29 18:42:27 (1 comments, 0 reshares, 10 +1s)Open 

"But whereas Earth’s thin atmosphere and distance from the Sun allows for liquid water on our planet’s surface, Venus’ carbon dioxide and sulfuric acid atmosphere, 90 times as thick as Earth’s and covered in constant layers of clouds, has become a cosmic oven."

Of all the worlds in our Solar System, Venus is perhaps the most like Earth. It’s the closest to us in size, in mass, in orbit, and in elemental content. The biggest difference, of course, is Venus’ atmosphere. Over 90 times as thick as Earth’s and composed of carbon dioxide and thick sulfuric acid clouds, the surface of Venus is at a constant 465C (870 F), making it the hottest planet in the Solar System. Yet we’ve both landed on the surface and imaged the entire world through its clouds, finding out exactly what the Venusian surface looks like. Come learn what you're looking at in advance of Tuesdayevening's b... more »

"But whereas Earth’s thin atmosphere and distance from the Sun allows for liquid water on our planet’s surface, Venus’ carbon dioxide and sulfuric acid atmosphere, 90 times as thick as Earth’s and covered in constant layers of clouds, has become a cosmic oven."

Of all the worlds in our Solar System, Venus is perhaps the most like Earth. It’s the closest to us in size, in mass, in orbit, and in elemental content. The biggest difference, of course, is Venus’ atmosphere. Over 90 times as thick as Earth’s and composed of carbon dioxide and thick sulfuric acid clouds, the surface of Venus is at a constant 465C (870 F), making it the hottest planet in the Solar System. Yet we’ve both landed on the surface and imaged the entire world through its clouds, finding out exactly what the Venusian surface looks like. Come learn what you're looking at in advance of Tuesday evening's big conjunction!___

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2015-06-27 13:25:02 (1 comments, 4 reshares, 22 +1s)Open 

“Ever since I was a child I have had this instinctive urge for expansion and growth. To me, the function and duty of a quality human being is the sincere and honest development of one’s potential.” -Bruce Lee

Stop-motion karate dueling is the most epic thing you've seen since you first discovered Mortal Kombat's fatalities!

“Ever since I was a child I have had this instinctive urge for expansion and growth. To me, the function and duty of a quality human being is the sincere and honest development of one’s potential.” -Bruce Lee

Stop-motion karate dueling is the most epic thing you've seen since you first discovered Mortal Kombat's fatalities!___

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2015-06-27 13:10:58 (7 comments, 6 reshares, 45 +1s)Open 

"It always fascinates me that the Milky Way is one of the least understood galaxies around, because our very presence within it prevents us from mapping it well. Just like you could never know your own eye color if it weren’t for reflective surfaces, photographs or other people telling you what it was, the fact that we’re inside the Milky Way itself works against us in tremendous ways."

Also: finding signs of life on exoplanets, how static electricity works, finding the first stars in the Universe and... who would win a battle royale among Disney princesses? My vote is for Merida, but I wouldn't put it past Mulan or Belle (!) to pull it off!

"It always fascinates me that the Milky Way is one of the least understood galaxies around, because our very presence within it prevents us from mapping it well. Just like you could never know your own eye color if it weren’t for reflective surfaces, photographs or other people telling you what it was, the fact that we’re inside the Milky Way itself works against us in tremendous ways."

Also: finding signs of life on exoplanets, how static electricity works, finding the first stars in the Universe and... who would win a battle royale among Disney princesses? My vote is for Merida, but I wouldn't put it past Mulan or Belle (!) to pull it off!___

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2015-06-26 16:55:48 (37 comments, 12 reshares, 48 +1s)Open 

"[T]he latest issue of Discover magazine has a long article on the “radical” theory of MOND and how its predictive power is excellent whereas anyone has yet to find even a trace of Dark Matter. My question is this: What is MOND? Is it a legitimate theory? If it is so successful, why do we only hear of Dark Matter and not MOND?"

When we look out at the galaxies in the Universe, watching how they rotate, we find that the starlight we see is woefully insufficient to explain why the galaxies move as they do. In fact, even if we add in the gas, dust, and all the known matter, it doesn’t add up. Normally, we talk about dark matter as the only viable solution, but it turns out that MOND, or MOdified Newtonian Dynamics, is actually superior at explaining galactic rotation to dark matter. Could it be the solution to the “missing mass” (or “missing light”) problem? A look at thefull suite of... more »

"[T]he latest issue of Discover magazine has a long article on the “radical” theory of MOND and how its predictive power is excellent whereas anyone has yet to find even a trace of Dark Matter. My question is this: What is MOND? Is it a legitimate theory? If it is so successful, why do we only hear of Dark Matter and not MOND?"

When we look out at the galaxies in the Universe, watching how they rotate, we find that the starlight we see is woefully insufficient to explain why the galaxies move as they do. In fact, even if we add in the gas, dust, and all the known matter, it doesn’t add up. Normally, we talk about dark matter as the only viable solution, but it turns out that MOND, or MOdified Newtonian Dynamics, is actually superior at explaining galactic rotation to dark matter. Could it be the solution to the “missing mass” (or “missing light”) problem? A look at the full suite of cosmological evidence reveals the answer, and sets out definitive challenges for MOND to overcome.___

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2015-06-25 23:56:38 (2 comments, 7 reshares, 31 +1s)Open 

"For centuries, it has been assumed that such contact charging derives from the spatially homogeneous material properties (along the material’s surface) and that within a given pair of materials, one charges uniformly positively and the other negatively. We demonstrate that this picture of contact charging is incorrect."

As one of the oldest known physical phenomena, static electricity was thought to be super simple: rub two objects together, one becomes positive and the other negative, and off you go! Only, that's not how it works at all, and we only discovered the truth in 2011. Happy Throwback Thursday, everyone.

"For centuries, it has been assumed that such contact charging derives from the spatially homogeneous material properties (along the material’s surface) and that within a given pair of materials, one charges uniformly positively and the other negatively. We demonstrate that this picture of contact charging is incorrect."

As one of the oldest known physical phenomena, static electricity was thought to be super simple: rub two objects together, one becomes positive and the other negative, and off you go! Only, that's not how it works at all, and we only discovered the truth in 2011. Happy Throwback Thursday, everyone.___

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2015-06-24 16:31:50 (0 comments, 0 reshares, 20 +1s)Open 

"Eventually, if this neutral gas gets dense enough, it should form the most elusive of all classes of stars: Population III stars, which to date, have only been theorized. Unlike super metal-rich stars like our Sun (Population I), which have seen many, many generations of stars form before, or metal-poor (Population II) stars, found in the halos of galaxies and in very young galaxies, where only a few generations of stars have lived-and-died before, these stars should be formed out of the gas left over from the Big Bang and nothing else."

When we look out into the Universe, farther back to greater distances, we’re also looking back in time, farther and farther into the past. If we could look back far enough, close enough to the Big Bang, we’d be able to see the very first stars ever formed in the Universe: stars formed from the Big Bang’s leftover material itself. We’d neverbeen ab... more »

"Eventually, if this neutral gas gets dense enough, it should form the most elusive of all classes of stars: Population III stars, which to date, have only been theorized. Unlike super metal-rich stars like our Sun (Population I), which have seen many, many generations of stars form before, or metal-poor (Population II) stars, found in the halos of galaxies and in very young galaxies, where only a few generations of stars have lived-and-died before, these stars should be formed out of the gas left over from the Big Bang and nothing else."

When we look out into the Universe, farther back to greater distances, we’re also looking back in time, farther and farther into the past. If we could look back far enough, close enough to the Big Bang, we’d be able to see the very first stars ever formed in the Universe: stars formed from the Big Bang’s leftover material itself. We’d never been able to find these before, but by looking at a starburst galaxy at extremely high redshifts, and measuring its signature spectroscopically, we were able to find strong evidence of hydrogen and helium, but none of carbon, oxygen, or any of the other “first-processed” elements we’d expect had we formed stars before. Here's why we think we've finally found the first true sample of Population III stars, with an actual exclusive interview with the lead scientist who made the discovery.___

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2015-06-23 21:05:04 (0 comments, 1 reshares, 11 +1s)Open 

Exoplanets and the seartch for habitable sowlrds. Live-blog and talk complete! #piCONVERGE

Exoplanets and the seartch for habitable sowlrds. Live-blog and talk complete! #piCONVERGE___

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2015-06-23 19:38:31 (2 comments, 0 reshares, 7 +1s)Open 

Almost time for Sara Seager's live talk / my live blog. Tune in at 4:10 ET/1:10 PT today! 

Almost time for Sara Seager's live talk / my live blog. Tune in at 4:10 ET/1:10 PT today! ___

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2015-06-22 18:28:12 (9 comments, 6 reshares, 26 +1s)Open 

“So the planets are there, the rocky planets are there, the rocky planets at the right distances from their stars for liquid water are there… and everything seems possible. If our best estimates for these planets are correct, there are literally billions of potentially habitable worlds in the Milky Way galaxy alone, right now.”

But how do we take that next great leap? How do we go from "potentially habitable" to worlds that are actually inhabited? How do we find them?

The secret lies in directly observing these worlds -- and their atmospheres -- something that NASA's proposed Starshade mission is capable of doing with present technology. And the PI of Starshade, Sara Seager, is speaking this Tuesday at 4:10 PM ET / 1:10 PM PT at Perimeter Institute's conference, Convergence, with an exclusive live-stream and live-blog by me!

“So the planets are there, the rocky planets are there, the rocky planets at the right distances from their stars for liquid water are there… and everything seems possible. If our best estimates for these planets are correct, there are literally billions of potentially habitable worlds in the Milky Way galaxy alone, right now.”

But how do we take that next great leap? How do we go from "potentially habitable" to worlds that are actually inhabited? How do we find them?

The secret lies in directly observing these worlds -- and their atmospheres -- something that NASA's proposed Starshade mission is capable of doing with present technology. And the PI of Starshade, Sara Seager, is speaking this Tuesday at 4:10 PM ET / 1:10 PM PT at Perimeter Institute's conference, Convergence, with an exclusive live-stream and live-blog by me!___

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2015-06-22 14:08:52 (8 comments, 36 reshares, 70 +1s)Open 

"So even though most particles in the Sun don’t have enough energy to get us there, it would only take a tiny percentage fusing together to power the Sun as we see it. So we do our calculations, we calculate how the protons in the Sun’s core have their energy distributed, and we come up with a number for these proton-proton collisions with sufficient energy to undergo nuclear fusion.

That number is exactly zero."

The Sun consists of some 10^57 particles, nearly 10% of which are in the core, which ranges from 4-15 million K, hot enough for nuclear fusion to occur. A whopping 4 × 10^38 protons fuse into helium-4 every second, and due to the temperatures and densities inside, the raw protons undergo billions of collisions during that time. Yet none of those collisions have a sufficient energy to overcome the Coulomb barrier; it's only through the power of quantummech... more »

"So even though most particles in the Sun don’t have enough energy to get us there, it would only take a tiny percentage fusing together to power the Sun as we see it. So we do our calculations, we calculate how the protons in the Sun’s core have their energy distributed, and we come up with a number for these proton-proton collisions with sufficient energy to undergo nuclear fusion.

That number is exactly zero."

The Sun consists of some 10^57 particles, nearly 10% of which are in the core, which ranges from 4-15 million K, hot enough for nuclear fusion to occur. A whopping 4 × 10^38 protons fuse into helium-4 every second, and due to the temperatures and densities inside, the raw protons undergo billions of collisions during that time. Yet none of those collisions have a sufficient energy to overcome the Coulomb barrier; it's only through the power of quantum mechanics that any fusion occurs. Without this inherent indeterminism, the Sun and practically every star in the night sky would be eternally dark.___

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2015-06-22 13:07:52 (4 comments, 18 reshares, 128 +1s)Open 

“But in order to form these new stars, and to drive the density waves that give galaxies their spiral shapes, galaxies require a “skeleton” of neutral, light-blocking atoms and molecules to underlie it all.”

While other galaxies tended to have high-density dust – infrared dark clouds – tracing out the backbones of their spiral arms, none had ever been discovered in the Milky Way. Until, that is, one of these “skeletal” features was discovered using the Spitzer Space Telescope in 2010. Recently, that “bone” was discovered to be even longer than suspected, and may be the central feature of the Scutum-Centaurus arm, the closest major spiral arm to the Sun.

“But in order to form these new stars, and to drive the density waves that give galaxies their spiral shapes, galaxies require a “skeleton” of neutral, light-blocking atoms and molecules to underlie it all.”

While other galaxies tended to have high-density dust – infrared dark clouds – tracing out the backbones of their spiral arms, none had ever been discovered in the Milky Way. Until, that is, one of these “skeletal” features was discovered using the Spitzer Space Telescope in 2010. Recently, that “bone” was discovered to be even longer than suspected, and may be the central feature of the Scutum-Centaurus arm, the closest major spiral arm to the Sun.___

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2015-06-22 01:14:06 (0 comments, 0 reshares, 11 +1s)Open 

Hey Portland, OR people! Don't forget, tomorrow evening, from 7-9 PM, to head over to the Hollywood theatre for my big event!

The Curiosity Club has, as part of their motto: “We admit that it is impossible to know everything about anything and thus we remain perpetually curious and perpetually novice.”

Want to find out when I was wrong about a very, very important scientific matter, and was confronted with mounting evidence showing I was wrong? Did I change my mind, and if so, what did it take? Come see me talk about my "successful failure," along with many others!

Hey Portland, OR people! Don't forget, tomorrow evening, from 7-9 PM, to head over to the Hollywood theatre for my big event!

The Curiosity Club has, as part of their motto: “We admit that it is impossible to know everything about anything and thus we remain perpetually curious and perpetually novice.”

Want to find out when I was wrong about a very, very important scientific matter, and was confronted with mounting evidence showing I was wrong? Did I change my mind, and if so, what did it take? Come see me talk about my "successful failure," along with many others!___

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2015-06-21 19:31:02 (1 comments, 1 reshares, 15 +1s)Open 

"[F]or some of us, it’s combining our past experiences with our own creativity that enables us to put out something new into the world, something that’s never been seen before.

In the case of Laura Cooper, comic creator and artist, that resulted in the combination of Disney princesses with velociraptors to create velociprincesses!"

Disney princesses reimagined as velociraptors: it's the most important thing you'll see all day, guaranteed!

"[F]or some of us, it’s combining our past experiences with our own creativity that enables us to put out something new into the world, something that’s never been seen before.

In the case of Laura Cooper, comic creator and artist, that resulted in the combination of Disney princesses with velociraptors to create velociprincesses!"

Disney princesses reimagined as velociraptors: it's the most important thing you'll see all day, guaranteed!___

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2015-06-20 14:46:04 (4 comments, 1 reshares, 20 +1s)Open 

"It's an interesting thought, and I see where it comes from:

* singularities at the centers of black holes are supposed to be regions of infinite density,
* with all the mass of a black hole concentrated into an infinitesimal volume of space,
* and therefore they should have infinite energy densities,
* yet you just said, Ethan, if the energy density exceeds a certain finite amount, we’d restore the inflationary state and destroy the Universe."

So why don't black holes restore the inflationary state and destroy the Universe? This and many other interesting follow up questions on our comments of the week!

"It's an interesting thought, and I see where it comes from:

* singularities at the centers of black holes are supposed to be regions of infinite density,
* with all the mass of a black hole concentrated into an infinitesimal volume of space,
* and therefore they should have infinite energy densities,
* yet you just said, Ethan, if the energy density exceeds a certain finite amount, we’d restore the inflationary state and destroy the Universe."

So why don't black holes restore the inflationary state and destroy the Universe? This and many other interesting follow up questions on our comments of the week!___

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2015-06-20 00:34:35 (1 comments, 12 reshares, 48 +1s)Open 

"This question has bothered me since I was a kid. If all the random molecular heat motion in an apple picked the same direction, how far would the apple go? And then what?"

Take a common, macroscopic object and imagine what’s going on inside at the level of individual particles. At a small, fundamental scale, they’re just bouncing off of one another, rapidly in motion due to the nature of kinetic theory. Each particle has a certain amount of energy, collides with other particles, and on average moves at a specific speed. If you aligned all these motions — somehow — how fast could you get that object to go? Pretty fast, it turns out: some 147 m/s, but there are two big physical reasons why that will never happen, one being momentum conservation and the other being that objects are solids. Find out the full story on this week's Ask Ethan!

"This question has bothered me since I was a kid. If all the random molecular heat motion in an apple picked the same direction, how far would the apple go? And then what?"

Take a common, macroscopic object and imagine what’s going on inside at the level of individual particles. At a small, fundamental scale, they’re just bouncing off of one another, rapidly in motion due to the nature of kinetic theory. Each particle has a certain amount of energy, collides with other particles, and on average moves at a specific speed. If you aligned all these motions — somehow — how fast could you get that object to go? Pretty fast, it turns out: some 147 m/s, but there are two big physical reasons why that will never happen, one being momentum conservation and the other being that objects are solids. Find out the full story on this week's Ask Ethan!___

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2015-06-18 22:53:28 (2 comments, 7 reshares, 33 +1s)Open 

"If someone tells you “the poles have shifted,” as some conspiracy theory sites may tell you periodically, this is a simple, straightforward and easy experiment you can perform to test it for yourself!

That’s one of the coolest things you can measure on the Solstice, and you don’t even need any astronomical equipment to do it. You could even do this, by following these same steps, on any planet."

Don't believe the conspiracy about the Earth's axial tilt changing. In fact, do one better and measure it for yourself, which you can do on Sunday, thanks to the solstice!

"If someone tells you “the poles have shifted,” as some conspiracy theory sites may tell you periodically, this is a simple, straightforward and easy experiment you can perform to test it for yourself!

That’s one of the coolest things you can measure on the Solstice, and you don’t even need any astronomical equipment to do it. You could even do this, by following these same steps, on any planet."

Don't believe the conspiracy about the Earth's axial tilt changing. In fact, do one better and measure it for yourself, which you can do on Sunday, thanks to the solstice!___

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2015-06-18 00:01:58 (10 comments, 17 reshares, 54 +1s)Open 

"[Y]our space would expand exponentially, be stretched flat, have the same properties everywhere, and when inflation came to an end, you’d get back a Universe that very much resembled our own. In addition, you’d also get five extra, new predictions out, things that all had not yet been observed at the time."

Inflation has five unique predictions that it made intrinsic to all (reasonable) models back in the 1980s, before any of them were known:

1.) A Flat Universe,
2.) A Universe with fluctuations on scales larger than light could’ve traveled across.
3.) A Universe whose fluctuations were adiabatic, or of equal entropy everywhere.
4.) A Universe where the spectrum of fluctuations were just slightly less than having a scale invariant (n_s
5.) And finally, a Universe with a particular spectrum of gravitational wave fluctuations.

How'd itdo? F... more »

"[Y]our space would expand exponentially, be stretched flat, have the same properties everywhere, and when inflation came to an end, you’d get back a Universe that very much resembled our own. In addition, you’d also get five extra, new predictions out, things that all had not yet been observed at the time."

Inflation has five unique predictions that it made intrinsic to all (reasonable) models back in the 1980s, before any of them were known:

1.) A Flat Universe,
2.) A Universe with fluctuations on scales larger than light could’ve traveled across.
3.) A Universe whose fluctuations were adiabatic, or of equal entropy everywhere.
4.) A Universe where the spectrum of fluctuations were just slightly less than having a scale invariant (n_s
5.) And finally, a Universe with a particular spectrum of gravitational wave fluctuations.

How'd it do? Find out!___

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2015-06-15 14:18:36 (14 comments, 10 reshares, 46 +1s)Open 

"Isn’t it time we did the best science that our technology had to offer? As great a success as Philae waking up is, and as much as we’ll learn over the coming months before it gets too hot and fries as it approaches the Sun, we’ll never know just how much more we would have learned if we didn’t lose those seven months, and whether or not those instrument failures would never have occurred if we simply used the technology we could have had to keep the equipment warm."

This past weekend, the Philae lander reawakened after seven dormant months, the best outcome that mission scientists could've hoped for with the way the mission unfolded. But the first probe to softly land on a comet ever would never have needed to hibernate at all if we had simply built it with the nuclear power capabilities it should've had. The seven months of lost data were completely unnecessary, andresulte... more »

"Isn’t it time we did the best science that our technology had to offer? As great a success as Philae waking up is, and as much as we’ll learn over the coming months before it gets too hot and fries as it approaches the Sun, we’ll never know just how much more we would have learned if we didn’t lose those seven months, and whether or not those instrument failures would never have occurred if we simply used the technology we could have had to keep the equipment warm."

This past weekend, the Philae lander reawakened after seven dormant months, the best outcome that mission scientists could've hoped for with the way the mission unfolded. But the first probe to softly land on a comet ever would never have needed to hibernate at all if we had simply built it with the nuclear power capabilities it should've had. The seven months of lost data were completely unnecessary, and resulted solely from the world's nuclear fears.___

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