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Top posts in the last 50 posts

Most comments: 27

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2016-02-06 16:57:41 (27 comments; 9 reshares; 26 +1s)Open 

"The interactions with Neptune or other objects in the Kuiper belt/Oort cloud are random and independent of anything else going on in our galaxy, but it’s possible that passing through a star-rich region — such as the galactic disk or one of our spiral arms — could enhance the odds of a comet storm, and the chance of a comet strike on Earth. The recent American Scientist paper that David asks about claims that there’s a roughly 26-30 million year “periodic” pattern in the extinctions on Earth, which correlates roughly with the 28-32 million year period of when the Solar System passes through the Milky Way’s galactic plane! Coincidence, or could this be the cause of the extinctions?"

Looking at the history of life on Earth, the fossil record shows something incontrovertible: in order for new forms of life to rise to dominance, it requires something to knock the prior formsfrom dominati... more »

Most reshares: 30

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2016-01-01 22:12:34 (9 comments; 30 reshares; 94 +1s)Open 

"1960s — After some 20 years of debate, the key observation that would decide the history of the Universe was uncovered: the discovery of the predicted leftover glow from the Big Bang, or the Cosmic Microwave Background. This uniform, 2.725 K radiation was discovered in 1965 by Arno Penzias and Bob Wilson, neither of whom realized what they had discovered at first. Yet over time, the full, blackbody spectrum of this radiation and even its fluctuations were measured, showing us that the Universe started with a “bang” after all."

Considering what we know about our Universe today, it’s hard to believe that just a century ago, Einstein’s General Relativity was very much untested and uncertain, and we hadn’t even realized that anything at all lie outside our own Milky Way. But over the past ten decades, ten great discoveries have taken place to give us the Universe we understandtoday.
more »

Most plusones: 94

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2016-01-01 22:12:34 (9 comments; 30 reshares; 94 +1s)Open 

"1960s — After some 20 years of debate, the key observation that would decide the history of the Universe was uncovered: the discovery of the predicted leftover glow from the Big Bang, or the Cosmic Microwave Background. This uniform, 2.725 K radiation was discovered in 1965 by Arno Penzias and Bob Wilson, neither of whom realized what they had discovered at first. Yet over time, the full, blackbody spectrum of this radiation and even its fluctuations were measured, showing us that the Universe started with a “bang” after all."

Considering what we know about our Universe today, it’s hard to believe that just a century ago, Einstein’s General Relativity was very much untested and uncertain, and we hadn’t even realized that anything at all lie outside our own Milky Way. But over the past ten decades, ten great discoveries have taken place to give us the Universe we understandtoday.
more »

Latest 50 posts

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2016-02-11 16:44:01 (22 comments; 17 reshares; 56 +1s)Open 

"And what we’ve seen, for the first time, is not just one of the greatest predictions of Einstein’s General Relativity, although we did just verify that. And it isn’t just that we took our first step into the world of gravitational wave astronomy, although LIGO will doubtlessly start seeing more of these signals over the coming years; this is as exciting for astronomy as Galileo’s invention of the telescope, as we’re seeing the Universe in a new way for the first time. But the biggest news of all is that we’ve just detected two merging black holes for the first time, tested their physics, found a tremendous agreement with Einstein, and seen evidence that this happens over a billion light years away across the Universe."

More than 100 years after Einstein’s relativity came out, one of its last great predictions — the existence of gravitational radiation — has beendirectly experime... more »

"And what we’ve seen, for the first time, is not just one of the greatest predictions of Einstein’s General Relativity, although we did just verify that. And it isn’t just that we took our first step into the world of gravitational wave astronomy, although LIGO will doubtlessly start seeing more of these signals over the coming years; this is as exciting for astronomy as Galileo’s invention of the telescope, as we’re seeing the Universe in a new way for the first time. But the biggest news of all is that we’ve just detected two merging black holes for the first time, tested their physics, found a tremendous agreement with Einstein, and seen evidence that this happens over a billion light years away across the Universe."

More than 100 years after Einstein’s relativity came out, one of its last great predictions — the existence of gravitational radiation — has been directly experimentally confirmed! The LIGO collaboration has observed two ~30 solar mass black holes merging together, producing a slightly less massive final black hole as three sun’s worth of mass was converted into energy via Einstein’s E = mc^2. This type of event, although quite serendipitous for the LIGO collaboration, is expected to occur between 2 and 4 times per year within the range of what LIGO can reach. Additionally, other types of mergers should be within the reach of what LIGO can see. Not only have we seen our first gravitational wave event, but we’re poised to truly begin the era of gravitational wave astronomy, as a new type of telescope is finally capable of seeing what’s happening in our Universe. ___

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2016-02-11 15:52:12 (0 comments; 7 reshares; 30 +1s)Open 

"The light from Vega was reduced by more than a factor of one billion, and many new stars that had never been seen before were discovered just by performing this simple test. By blocking the starlight using this new concept — the starshade — we were able to view objects closer to the star than ever before. The next step? Get one into orbit and empower it to work with a Hubble-class (or greater!) optical space telescope. We’ll be able to see the light directly from dozens of rocky planets, for the first time, including their spectra as the planet rotates and revolves in its own orbit."

25 years ago, there were no planets known around Sun-like stars other than our own. Just 5 years ago, there were no rocky planets known around Sun-like stars other than our own. And today, we don’t have any direct images of those rocky worlds potentially suitable for life. But in just another tento fift... more »

"The light from Vega was reduced by more than a factor of one billion, and many new stars that had never been seen before were discovered just by performing this simple test. By blocking the starlight using this new concept — the starshade — we were able to view objects closer to the star than ever before. The next step? Get one into orbit and empower it to work with a Hubble-class (or greater!) optical space telescope. We’ll be able to see the light directly from dozens of rocky planets, for the first time, including their spectra as the planet rotates and revolves in its own orbit."

25 years ago, there were no planets known around Sun-like stars other than our own. Just 5 years ago, there were no rocky planets known around Sun-like stars other than our own. And today, we don’t have any direct images of those rocky worlds potentially suitable for life. But in just another ten to fifteen years, that might not be true anymore. By blocking out the light in front of a star, you can potentially see the light from the faint planet instead. While conventional coronagraphs might reduce the amount of light transmitted by a factor of one million, a hypergaussian surface at the right distance — a starshade — can reduce the star’s light by a factor of over 10^10, making direct exoplanet imaging possible.___

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2016-02-09 17:14:39 (6 comments; 6 reshares; 34 +1s)Open 

"[I]f they find a gravitational wave, this is what it’ll teach us: that Einstein’s relativity is right, that gravitational radiation is real, and that merging black holes not only produce them, but that these waves can be detected. It’s a whole new type of astronomy — one that doesn’t use telescopes — and a whole new way to view black holes, neutron stars, and other objects that are otherwise mostly invisible. For the first time, we may be developing eyes for examining the Universe in a way that no living creature has ever examined it before."

When we look out into the Universe, we normally gain information about it by gathering light of various wavelengths. However, there are other possibilities for astronomy, including by looking for the neutrinos emitted by astrophysical sources — first detected in the supernova explosion of 1987 — and in the gravitational wavesemitted by acce... more »

"[I]f they find a gravitational wave, this is what it’ll teach us: that Einstein’s relativity is right, that gravitational radiation is real, and that merging black holes not only produce them, but that these waves can be detected. It’s a whole new type of astronomy — one that doesn’t use telescopes — and a whole new way to view black holes, neutron stars, and other objects that are otherwise mostly invisible. For the first time, we may be developing eyes for examining the Universe in a way that no living creature has ever examined it before."

When we look out into the Universe, we normally gain information about it by gathering light of various wavelengths. However, there are other possibilities for astronomy, including by looking for the neutrinos emitted by astrophysical sources — first detected in the supernova explosion of 1987 — and in the gravitational waves emitted by accelerating masses. These ripples in the fabric of space were theorized back in the early days of Einstein’s General Relativity, and experiments to detect them have been ongoing since the 1960s. However, in September of 2015, Advanced LIGO came online, and it was the first gravitational wave observatory that was expected to detect a real gravitational wave signal. The press conference on Thursday is where the collaboration will make their official announcement, and in the meantime, here’s an explainer of what gravitational waves are, what Advanced LIGO can teach us, and how.___

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2016-02-08 21:52:19 (4 comments; 7 reshares; 21 +1s)Open 

"You can build a refracting telescope, where the lens focuses the light, as large as you want, with no problem. But lenses are heavy, expensive, and limited in size by practical constraints. Reflecting allows you to go bigger, since large (or segmented) mirrors are easier to build than lenses, but the light must be focused in front of the primary mirror. That means you need a secondary mirror/apparatus, which otherwise interferes with the incoming light and produces unwanted image artifacts. "

When you look at the largest, most powerful optical telescopes in the world, they all have something in common: they all have holes in their central, primary mirrors. This is for a few reasons, including that they’re all reflectors, they all need to focus light somewhere in front of the mirror, and they all need to send that light somewhere to be recorded and analyzed. You can, in principle,f... more »

"You can build a refracting telescope, where the lens focuses the light, as large as you want, with no problem. But lenses are heavy, expensive, and limited in size by practical constraints. Reflecting allows you to go bigger, since large (or segmented) mirrors are easier to build than lenses, but the light must be focused in front of the primary mirror. That means you need a secondary mirror/apparatus, which otherwise interferes with the incoming light and produces unwanted image artifacts. "

When you look at the largest, most powerful optical telescopes in the world, they all have something in common: they all have holes in their central, primary mirrors. This is for a few reasons, including that they’re all reflectors, they all need to focus light somewhere in front of the mirror, and they all need to send that light somewhere to be recorded and analyzed. You can, in principle, focus the light somewhere off-axis, and many amateur telescopes do, but for the professionals, you lose more light that way than you would by simply having a hole in the center. In order to conserve the most light and maximize the image quality with the fewest artifacts, leaving a hole in the mirror is by far the best way to go.___

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2016-02-07 18:06:03 (0 comments; 5 reshares; 9 +1s)Open 

""In a typical application, a collection of relatively slow (low temperature) atoms are contained in a trap of electric and magnetic fields. The system is tuned in such a way that the fastest moving atoms can escape out of the trap (and stick to the walls), while the slow ones are turned around and kept in place by the field configuration.
Over time, you end up with a fewer atoms, but the collection is all together much colder (nanokelvins or below).”

This is one of the most important techniques in getting that extra significant digit lower in our quest for absolute zero, to go from microK to nanoK to all the way down to (I believe) hundreds of picoK at the lowest. It’s absolutely a wonderful technique, and it’s the same principle as cooling your coffee: you remove the hottest particles in the distribution and you’re left with a smaller number of particles with a loweraverage... more »

""In a typical application, a collection of relatively slow (low temperature) atoms are contained in a trap of electric and magnetic fields. The system is tuned in such a way that the fastest moving atoms can escape out of the trap (and stick to the walls), while the slow ones are turned around and kept in place by the field configuration.
Over time, you end up with a fewer atoms, but the collection is all together much colder (nanokelvins or below).”

This is one of the most important techniques in getting that extra significant digit lower in our quest for absolute zero, to go from microK to nanoK to all the way down to (I believe) hundreds of picoK at the lowest. It’s absolutely a wonderful technique, and it’s the same principle as cooling your coffee: you remove the hottest particles in the distribution and you’re left with a smaller number of particles with a lower average temperature. In principle, you can keep this up and leave yourself with a tiny number of particles in an incredibly cold state, for any initial temperature configuration."

If we were entangled with an alternate-Universe version of ourselves, would we know? Could neutron stars spin faster than we actually see? Does blowing across your coffee cool it, and why? All this and more on our comments of the week!___

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2016-02-06 16:57:41 (27 comments; 9 reshares; 26 +1s)Open 

"The interactions with Neptune or other objects in the Kuiper belt/Oort cloud are random and independent of anything else going on in our galaxy, but it’s possible that passing through a star-rich region — such as the galactic disk or one of our spiral arms — could enhance the odds of a comet storm, and the chance of a comet strike on Earth. The recent American Scientist paper that David asks about claims that there’s a roughly 26-30 million year “periodic” pattern in the extinctions on Earth, which correlates roughly with the 28-32 million year period of when the Solar System passes through the Milky Way’s galactic plane! Coincidence, or could this be the cause of the extinctions?"

Looking at the history of life on Earth, the fossil record shows something incontrovertible: in order for new forms of life to rise to dominance, it requires something to knock the prior formsfrom dominati... more »

"The interactions with Neptune or other objects in the Kuiper belt/Oort cloud are random and independent of anything else going on in our galaxy, but it’s possible that passing through a star-rich region — such as the galactic disk or one of our spiral arms — could enhance the odds of a comet storm, and the chance of a comet strike on Earth. The recent American Scientist paper that David asks about claims that there’s a roughly 26-30 million year “periodic” pattern in the extinctions on Earth, which correlates roughly with the 28-32 million year period of when the Solar System passes through the Milky Way’s galactic plane! Coincidence, or could this be the cause of the extinctions?"

Looking at the history of life on Earth, the fossil record shows something incontrovertible: in order for new forms of life to rise to dominance, it requires something to knock the prior forms from dominating their ecological niche. This can come about in any number of ways, but the most striking changes come from catastrophic events that wipe a large percentage of species off the Earth at once: a mass extinction event. While the asteroid strike that wiped out the dinosaurs was perhaps the most famous one, there is bountiful evidence that there were many others over the past 500 million years, with perhaps some periodicity to these events. Recently, reports have emerged that our Sun’s passage through the galactic plane, with periods of 26-30 million years, might correlate with these events. Yet a look at the fossil record shows extinction events do not have the required periodicity to account for that, nor do Oort cloud strikes account for the majority of such events on Earth.___

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2016-02-06 00:26:40 (0 comments; 7 reshares; 43 +1s)Open 

"This is why we look, and this is what science at the frontiers is. The Giant Magellan Telescope will do all the things from the ground that space-based telescopes can’t do as well, and will do them better than any other telescope in existence. Unlike the other large ground-based telescopes planned, it’s completely privately funded, there are no political controversies over it, and construction on it has already begun. The future of any scientific endeavor — and perhaps astronomy in particular — requires you to be ambitious, and to invest in looking for the unknown. We’ll never learn what lies beyond our current frontiers of knowledge unless we search, and the GMT is one major step towards looking where no one has ever looked before."

If you want to see farther, deeper and at higher resolution than ever before into the Universe, you need four things: the largest aperturepossible,... more »

"This is why we look, and this is what science at the frontiers is. The Giant Magellan Telescope will do all the things from the ground that space-based telescopes can’t do as well, and will do them better than any other telescope in existence. Unlike the other large ground-based telescopes planned, it’s completely privately funded, there are no political controversies over it, and construction on it has already begun. The future of any scientific endeavor — and perhaps astronomy in particular — requires you to be ambitious, and to invest in looking for the unknown. We’ll never learn what lies beyond our current frontiers of knowledge unless we search, and the GMT is one major step towards looking where no one has ever looked before."

If you want to see farther, deeper and at higher resolution than ever before into the Universe, you need four things: the largest aperture possible, the best-quality optical systems and cameras/CCDs, the least interference from the atmosphere, and the analytical techniques and power to make the most of every photon. While the last three have improved tremendously over the past 25 years, telescope size hasn’t increased at all. That’s all about to change over the next decade, as three telescopes — the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope — are set to take us from 8-10 meter class astronomy to 25-40 meter class. While the latter two are fighting over funding, construction rights and other political concerns, the Giant Magellan Telescope is already under construction, and is poised to be the first in line to begin the future of ground-based astronomy.___

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2016-02-05 02:23:47 (6 comments; 22 reshares; 40 +1s)Open 

"But did the Big Bang happen? By the first definition, yes, absolutely: the Universe emerged from a hot, dense, uniform and rapidly expanding state, and has been cooling and getting less dense ever since. But if you’re using the second definition, you may really want to rethink using the term “the Big Bang.” You won’t be the only one using it that way, but your assumptions — and your conclusions — might be completely wrong."

It’s making headlines every time someone brings it up: a quantum calculation, a new theory or some mathematical evidence proves it once and for all: there was no Big Bang. Is that even possible? Honestly, it depends on which definition of the Big Bang you’re using. As it turns out, there are two of them, and there’s a good (historical) reason for that. But in the context of what we know today, one of them isn’t a good definition anymore, andhasn’t been for dec... more »

"But did the Big Bang happen? By the first definition, yes, absolutely: the Universe emerged from a hot, dense, uniform and rapidly expanding state, and has been cooling and getting less dense ever since. But if you’re using the second definition, you may really want to rethink using the term “the Big Bang.” You won’t be the only one using it that way, but your assumptions — and your conclusions — might be completely wrong."

It’s making headlines every time someone brings it up: a quantum calculation, a new theory or some mathematical evidence proves it once and for all: there was no Big Bang. Is that even possible? Honestly, it depends on which definition of the Big Bang you’re using. As it turns out, there are two of them, and there’s a good (historical) reason for that. But in the context of what we know today, one of them isn’t a good definition anymore, and hasn’t been for decades.___

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2016-02-03 23:50:08 (1 comments; 2 reshares; 27 +1s)Open 

The live-blog of Vicky Kaspi's talk on neutron stars begins now!

http://www.forbes.com/sites/startswithabang/2016/02/03/the-cosmic-gift-of-neutron-stars-a-live-blog-event/#5a83647c2884

Tweet your questions with the hashtag #piLIVE.

The live-blog of Vicky Kaspi's talk on neutron stars begins now!

http://www.forbes.com/sites/startswithabang/2016/02/03/the-cosmic-gift-of-neutron-stars-a-live-blog-event/#5a83647c2884

Tweet your questions with the hashtag #piLIVE.___

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2016-02-03 17:46:35 (9 comments; 9 reshares; 25 +1s)Open 

"These massive, collapsed entities are neutron stars, coming in at up to three times the mass of our Sun, yet are no bigger than a large city like Washington, D.C. They are some of the most extreme objects in our Universe, and they enable us to explore some amazing things..."

Neutron stars are some of the most extreme objects in the Universe: a ball of neutrons a few kilometers in diameter, but with more mass than the entire Sun in them. Their magnetic fields are around a trillion times as strong as our Sun’s, they rotate at around 2/3 the speed of light, and they arise from the catastrophic supernovae of some of the Universe’s most massive stars. Later today, Vicky Kaspi will give Perimeter Institute’s public lecture on neutron stars and the great cosmic gift that they are to us. I highly recommend following along on my live blog, a unique experience to see an informed,profe... more »

"These massive, collapsed entities are neutron stars, coming in at up to three times the mass of our Sun, yet are no bigger than a large city like Washington, D.C. They are some of the most extreme objects in our Universe, and they enable us to explore some amazing things..."

Neutron stars are some of the most extreme objects in the Universe: a ball of neutrons a few kilometers in diameter, but with more mass than the entire Sun in them. Their magnetic fields are around a trillion times as strong as our Sun’s, they rotate at around 2/3 the speed of light, and they arise from the catastrophic supernovae of some of the Universe’s most massive stars. Later today, Vicky Kaspi will give Perimeter Institute’s public lecture on neutron stars and the great cosmic gift that they are to us. I highly recommend following along on my live blog, a unique experience to see an informed, professional astrophysicist give commentary and extra detail to another’s professional talk!

Tune in at 7:00 PM ET / 4:00 PM PT and don't miss it!___

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2016-02-02 22:32:21 (9 comments; 3 reshares; 20 +1s)Open 

"Unfortunately, this is one of those cases where our mathematical intuition and what actual probabilities are don’t line up at all. If you have a fair (50/50) coin at play in each instance, it’s true you’re more likely to have three “wins” for each candidate than any other specific outcome. But it’s still not all that likely: there’s only a 31.25% chance that Clinton and Sanders would have walked away with three delegates apiece. Furthermore, the odds that Clinton would win four and Sanders would win two is only a little worse: 23.44%. But if you combine that with the odds that Sanders would’ve won four with Clinton winning two, you get that a 4:2 outcome has a 46.88% chance of happening. Meaning the “unlikely” outcomes of 5:1 or 6:0? They actually have a 21.88% chance of occurring, which is about the same as your odds of winning any prize at all (most likely, $4) if you buy sixrandom Powerball ti... more »

"Unfortunately, this is one of those cases where our mathematical intuition and what actual probabilities are don’t line up at all. If you have a fair (50/50) coin at play in each instance, it’s true you’re more likely to have three “wins” for each candidate than any other specific outcome. But it’s still not all that likely: there’s only a 31.25% chance that Clinton and Sanders would have walked away with three delegates apiece. Furthermore, the odds that Clinton would win four and Sanders would win two is only a little worse: 23.44%. But if you combine that with the odds that Sanders would’ve won four with Clinton winning two, you get that a 4:2 outcome has a 46.88% chance of happening. Meaning the “unlikely” outcomes of 5:1 or 6:0? They actually have a 21.88% chance of occurring, which is about the same as your odds of winning any prize at all (most likely, $4) if you buy six random Powerball tickets."

Coin flips are traditionally the way to settle disputes with two choices and equal probabilities. They're ubiquitous not only in sporting events, but in events as important as elections, with thirty five states having adopted a coin flip as their official tiebreaker method. Yesterday, in Iowa, the democratic election was so close that there were six county delegate seats that needed to be decided by coin flip. Hillary Clinton won all six, leading some to speculate that there must be some foul play at work. However, a closer look at the odds revealed what you might have suspected all along: that quite often, the probability of one of many unlikely outcomes can be just as high than the probability of one of the most likely outcomes. In other words, there's no reason to suspect foul play at all.___

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2016-02-02 17:10:32 (4 comments; 5 reshares; 18 +1s)Open 

"If you’ve ever observed steam rising off your hot beverage, that’s actually arising from the hottest, most energetic molecules inside entering the gaseous phase, condensing back into rising liquid droplets as the cool air above interacts with them. (Which is why, if you put your nose above a steaming cup of coffee, it comes out not just hot, but also wet!)"

Particularly in the dead of winter, most of us enjoy a hot drink, whether it’s coffee, tea, hot chocolate or soup. But if that drink is too hot, your options for cooling it down are unsatisfying: wait for the room to cool it, which takes forever, drop an ice cube in, which waters down your drink, or blow on it. While blowing on your drink may seem ineffective, as the breath inside your body is generally warmer than the ambient air, there’s an additional feature that makes blowing on it totally worth it: the circulation andexposur... more »

"If you’ve ever observed steam rising off your hot beverage, that’s actually arising from the hottest, most energetic molecules inside entering the gaseous phase, condensing back into rising liquid droplets as the cool air above interacts with them. (Which is why, if you put your nose above a steaming cup of coffee, it comes out not just hot, but also wet!)"

Particularly in the dead of winter, most of us enjoy a hot drink, whether it’s coffee, tea, hot chocolate or soup. But if that drink is too hot, your options for cooling it down are unsatisfying: wait for the room to cool it, which takes forever, drop an ice cube in, which waters down your drink, or blow on it. While blowing on your drink may seem ineffective, as the breath inside your body is generally warmer than the ambient air, there’s an additional feature that makes blowing on it totally worth it: the circulation and exposure-to-air of the hot fluid vastly increases the rate of evaporation, taking the highest-kinetic-energy molecules out of the equation and cooling your drink more quickly.___

2016-02-02 00:30:01 (0 comments; 2 reshares; 17 +1s)Open 

"In 1930, Clyde Tombaugh serendipitously discovered Pluto: the first object in our Solar System out past Neptune. For 48 years, it was the only object known out there, until Charon -- its giant moon -- was discovered. But the 1990s brought with it a slew of Kuiper Belt objects, and in 2006, Pluto was officially demoted to a "dwarf planet." But also in 2006, NASA's New Horizons mission was launched: the first dedicated mission to the outer Solar System. In 2015, it flew by both Pluto and Charon, discovering two vastly different worlds. Here's what we've learned."

The latest Starts With A Bang podcast is out: on Pluto, Charon, and why they're so different!

"In 1930, Clyde Tombaugh serendipitously discovered Pluto: the first object in our Solar System out past Neptune. For 48 years, it was the only object known out there, until Charon -- its giant moon -- was discovered. But the 1990s brought with it a slew of Kuiper Belt objects, and in 2006, Pluto was officially demoted to a "dwarf planet." But also in 2006, NASA's New Horizons mission was launched: the first dedicated mission to the outer Solar System. In 2015, it flew by both Pluto and Charon, discovering two vastly different worlds. Here's what we've learned."

The latest Starts With A Bang podcast is out: on Pluto, Charon, and why they're so different!___

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2016-02-01 15:51:45 (1 comments; 3 reshares; 17 +1s)Open 

"The gas gets compressed by the star’s motion so severely that molecular collisions cause dramatic gas heating. The gas then radiates that heat away, which it does in the infrared or even — at high enough energies — in visible light.

By getting a strong “kick” from an exploding star or a gravitationally bound cluster, these stars obtain large velocities relative to most others in the Milky Way."

Travel fast enough through the air, and you’ll exceed the speed of sound. The compressed air in front of you builds up, denser and denser, creating a shock wherever you’ve exceeded the sound barrier. In interstellar space, stars that move fast enough do the exact same thing.
There doesn’t need to be sound in space for runaway stars to compress gas, heating it and causing it to radiate. Our infrared space telescopes, like NASA’s Spitzer and WISE, are ideal foridentifying and i... more »

"The gas gets compressed by the star’s motion so severely that molecular collisions cause dramatic gas heating. The gas then radiates that heat away, which it does in the infrared or even — at high enough energies — in visible light.

By getting a strong “kick” from an exploding star or a gravitationally bound cluster, these stars obtain large velocities relative to most others in the Milky Way."

Travel fast enough through the air, and you’ll exceed the speed of sound. The compressed air in front of you builds up, denser and denser, creating a shock wherever you’ve exceeded the sound barrier. In interstellar space, stars that move fast enough do the exact same thing.
There doesn’t need to be sound in space for runaway stars to compress gas, heating it and causing it to radiate. Our infrared space telescopes, like NASA’s Spitzer and WISE, are ideal for identifying and imaging these stellar bow shocks. Hundreds have been identified so far, with thousands to millions likely in every galaxy overall.___

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2016-01-30 16:46:51 (7 comments; 0 reshares; 7 +1s)Open 

"Are you sure about the potential for refueling? I have been unable to get a definitive answer on that. Seemingly every time someone says the potential exists, someone else says the JWST doesn’t have refueling ports and the technology to pull off such a mission would be more expensive than simply putting a new and better telescope out there. Both stories sound plausible. Do you have details on which is the straight scoop?"

Some great comments, some thoughtful questions and some legitimately good thoughts to dig into here. It's the end-of-the-week recap on our comments of the week!

"Are you sure about the potential for refueling? I have been unable to get a definitive answer on that. Seemingly every time someone says the potential exists, someone else says the JWST doesn’t have refueling ports and the technology to pull off such a mission would be more expensive than simply putting a new and better telescope out there. Both stories sound plausible. Do you have details on which is the straight scoop?"

Some great comments, some thoughtful questions and some legitimately good thoughts to dig into here. It's the end-of-the-week recap on our comments of the week!___

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2016-01-30 15:19:05 (8 comments; 4 reshares; 20 +1s)Open 

“In what way, if at all, are the ideas of Everettian Quantum Mechanics and Eternal Inflation related? Can we distinguish between the multiverse as implied by each?”

When you think about the Multiverse, everyone thinks about the Universe beyond what’s accessible to us. But whether you think about more Universe like our own, multiple Universe that are disconnected from ours, an infinite number of parallel Universes, where possibly multiple copies of identical “yous” are entangled, or where the laws of physics are different from our own depends on what type of Multiverse you’re talking about. As it turns out, our standard picture of inflation, the Big Bang and quantum physics leads to some of these being quite likely, with others being grossly disfavored. Before you follow the speculations of a great many others down whatever rabbit-hole of thought they’d lead you, come learn aboutwhat’s known,... more »

“In what way, if at all, are the ideas of Everettian Quantum Mechanics and Eternal Inflation related? Can we distinguish between the multiverse as implied by each?”

When you think about the Multiverse, everyone thinks about the Universe beyond what’s accessible to us. But whether you think about more Universe like our own, multiple Universe that are disconnected from ours, an infinite number of parallel Universes, where possibly multiple copies of identical “yous” are entangled, or where the laws of physics are different from our own depends on what type of Multiverse you’re talking about. As it turns out, our standard picture of inflation, the Big Bang and quantum physics leads to some of these being quite likely, with others being grossly disfavored. Before you follow the speculations of a great many others down whatever rabbit-hole of thought they’d lead you, come learn about what’s known, what’s expected and what’s highly speculative (and unobservable) based on our current knowledge.___

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2016-01-29 00:39:54 (10 comments; 5 reshares; 37 +1s)Open 

"The gravitational interactions are particularly interesting, because whenever you have three bodies interacting, two often become more tightly bound while the third gets a “kick,” potentially ejecting it. This is how we use planets to assist spacecrafts in their journey towards the outer Solar System, and the same principle can allow gas clouds to be ejected from our own galaxy. In one very particular, peculiar case, however, a gas cloud in our own galaxy almost got kicked out, but not quite."

Give a planet a kick, and it goes into a more distant orbit around our star. Give it a hard enough kick, and it will reach escape velocity, leaving our Solar System forever. But if you gave it an almost hard enough kick, it would travel extremely far from the Sun, but it would eventually boomerang back towards the inner Solar System, with potentially disastrous, disruptive consequences. Thisapp... more »

"The gravitational interactions are particularly interesting, because whenever you have three bodies interacting, two often become more tightly bound while the third gets a “kick,” potentially ejecting it. This is how we use planets to assist spacecrafts in their journey towards the outer Solar System, and the same principle can allow gas clouds to be ejected from our own galaxy. In one very particular, peculiar case, however, a gas cloud in our own galaxy almost got kicked out, but not quite."

Give a planet a kick, and it goes into a more distant orbit around our star. Give it a hard enough kick, and it will reach escape velocity, leaving our Solar System forever. But if you gave it an almost hard enough kick, it would travel extremely far from the Sun, but it would eventually boomerang back towards the inner Solar System, with potentially disastrous, disruptive consequences. This applies to any system (not just the Solar System), including our own galaxy. In the Milky Way’s outskirts, there are high-velocity gas clouds, including one — the Smith Cloud — that’s moving towards us at a breakneck pace. Thanks to data from the Hubble Space Telescope, Andrew Fox and his team have just uncovered that this cloud came from our Milky Way, was almost ejected into intergalactic space, but is now on its way back, where in 30 million years it will collide with our galactic disk. The 11,000 light year-long cloud is expected to produce over 2 million new stars when it does.___

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2016-01-28 19:27:36 (3 comments; 6 reshares; 43 +1s)Open 

"If JWST works as expected, it’s carrying enough fuel on-board that it should operate from 2018 through 2028, and although it’s never been done, the potential exists for a robotic (or crewed, if the technology gets developed by then) re-fueling mission to L2, which could increase the telescope’s lifetime by another decade. Just as Hubble’s been in operation for 25 years and counting, JWST could give us a generation of revolutionary science if things work out as well as they could. It’s the future of astronomy, and after more than a decade of hard work, it’s almost time to come to fruition."

In 1990, the Hubble Space Telescope was launched and deployed, becoming the first space-based observatory. In the years since, many others have followed, covering the entire electromagnetic spectrum, but with nothing superseding Hubble over the wavelengths it covers. That will all changewith the Ja... more »

"If JWST works as expected, it’s carrying enough fuel on-board that it should operate from 2018 through 2028, and although it’s never been done, the potential exists for a robotic (or crewed, if the technology gets developed by then) re-fueling mission to L2, which could increase the telescope’s lifetime by another decade. Just as Hubble’s been in operation for 25 years and counting, JWST could give us a generation of revolutionary science if things work out as well as they could. It’s the future of astronomy, and after more than a decade of hard work, it’s almost time to come to fruition."

In 1990, the Hubble Space Telescope was launched and deployed, becoming the first space-based observatory. In the years since, many others have followed, covering the entire electromagnetic spectrum, but with nothing superseding Hubble over the wavelengths it covers. That will all change with the James Webb Space Telescope, currently on schedule and almost ready for its October 2018 launch date. The science instruments are all complete, the final mirrors are being inserted into the optical assembly, the sunshield (a new, innovative component) is almost complete, and then it just needs assembly and launch. When it’s all said and done, JWST will be orders of magnitude greater than all the other observatories that came before, and will finally allow us to truly see the first stars, galaxies and quasars in the Universe, not limited by the obscuring neutral gas that currently blocks our view with other observatories.___

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2016-01-27 17:03:41 (2 comments; 4 reshares; 19 +1s)Open 

"You sort of have to put that out of your mind. There’s always a possibility that you can have a catastrophic failure, of course; this can happen on any flight; it can happen on the last one as well as the first one. So, you just plan as best you can to take care of all these eventualities, and you get a well-trained crew and you go fly."

On January 27, 1967, the Apollo 1 crew was performing a “plugs-out” test of the Command/Service Module, an essential simulation of how the three-person capsule would perform under in-space conditions under its own power. At 6:30 PM, a voltage spike occurred, leading to a disaster. In 26 seconds, everything changed. The Apollo 1 fire and the tragic death of all three astronauts wasn’t due to just a single point-of-failure, but rather due to five independent confounding factors that if any one of them had been different, the astronauts Grissom,White a... more »

"You sort of have to put that out of your mind. There’s always a possibility that you can have a catastrophic failure, of course; this can happen on any flight; it can happen on the last one as well as the first one. So, you just plan as best you can to take care of all these eventualities, and you get a well-trained crew and you go fly."

On January 27, 1967, the Apollo 1 crew was performing a “plugs-out” test of the Command/Service Module, an essential simulation of how the three-person capsule would perform under in-space conditions under its own power. At 6:30 PM, a voltage spike occurred, leading to a disaster. In 26 seconds, everything changed. The Apollo 1 fire and the tragic death of all three astronauts wasn’t due to just a single point-of-failure, but rather due to five independent confounding factors that if any one of them had been different, the astronauts Grissom, White and Chaffee might have survived. As it stands, all the crewed Apollo missions were scrapped for 20 months while NASA changed how they did business. The changes worked remarkably well, and 2.5 years later, humans walked on the Moon.___

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2016-01-25 15:29:59 (4 comments; 4 reshares; 45 +1s)Open 

“Until the gas is completely ionized, visible light can be reflected or absorbed, depending on the orientation of the stars and gas with respect to us. The only way to see through neutral gas is by looking in the infrared, which is sensitive to other features. Once the gas is 100% ionized, it’s 100% transparent, and the entire Universe is revealed.”

The distant nebulae might appear to illuminate the night sky, but this neutral gas is mostly only good for reflecting or absorbing starlight, which obscures the view of all the stars and galaxies lying in the background. But this light-blocking effect is only temporary, as over time, this neutral gas will give way to transparency. All it takes is the energy of the hot, blue stars forming inside, whose ultraviolet radiation will eventually ionize all of the material within it. The last gasps of the neutral gas will appear as Evaporating GasGlobu... more »

“Until the gas is completely ionized, visible light can be reflected or absorbed, depending on the orientation of the stars and gas with respect to us. The only way to see through neutral gas is by looking in the infrared, which is sensitive to other features. Once the gas is 100% ionized, it’s 100% transparent, and the entire Universe is revealed.”

The distant nebulae might appear to illuminate the night sky, but this neutral gas is mostly only good for reflecting or absorbing starlight, which obscures the view of all the stars and galaxies lying in the background. But this light-blocking effect is only temporary, as over time, this neutral gas will give way to transparency. All it takes is the energy of the hot, blue stars forming inside, whose ultraviolet radiation will eventually ionize all of the material within it. The last gasps of the neutral gas will appear as Evaporating Gas Globules (EGGs), and when they’re all completely ionized, the starlight from everything beyond will be free to stream towards our eyes unimpeded.

Go get the full story in pictures, video and no more than 200 words on today’s Mostly Mute Monday!___

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2016-01-23 16:45:53 (0 comments; 1 reshares; 9 +1s)Open 

"To someone who’s never done experimental or observational work, this might seem like the ultimate example of fooling yourself. But there’s a good reason for it: there are two types of errors, statistical (where you can improve on your errors by taking more data/doing more experiments), and systematic, where you need to calibrate/account for a variety of effects having to do with your equipment, sources, objects, and experimental setup. Sometimes you get results that aren’t what you expect, and that’s often because of systematic errors. In fact, that’s often how systematic errors get caught. Unfortunately, we (scientists) suffer from the bias that when we’ve identified all the systematic errors we can and we get a result that’s in alignment with our expectations, we stop looking for new systematics. And that’s how this problem — at least in my experience — often self-perpetuates.Erring on the other... more »

"To someone who’s never done experimental or observational work, this might seem like the ultimate example of fooling yourself. But there’s a good reason for it: there are two types of errors, statistical (where you can improve on your errors by taking more data/doing more experiments), and systematic, where you need to calibrate/account for a variety of effects having to do with your equipment, sources, objects, and experimental setup. Sometimes you get results that aren’t what you expect, and that’s often because of systematic errors. In fact, that’s often how systematic errors get caught. Unfortunately, we (scientists) suffer from the bias that when we’ve identified all the systematic errors we can and we get a result that’s in alignment with our expectations, we stop looking for new systematics. And that’s how this problem — at least in my experience — often self-perpetuates. Erring on the other side, by the way, is what leads to the OPERA faster-than-light neutrinos, where you fail to get all your systematics before publishing!"

One blog, eight posts this past week, and some dozen internet comments called out for... well, you'll just have to read and find out!___

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2016-01-23 16:19:27 (21 comments; 8 reshares; 24 +1s)Open 

"Are we all just brain cells in a larger creature, on a planetary scale, that has yet to become self-aware? How would we know? How could we test this?"

The analogies between small-scale, living things and large-scale, cosmic entities are abundant: between a neuron and the Universe’s large-scale structure; between an atom and a solar system; between the stars in a galaxy and the atoms in a cell; between the cells in a living being and the galaxies in the Universe. It makes you wonder if, on a cosmic scale, some portion (or the whole) of the Universe could actually be alive and self-aware?
While we don’t yet know how to test for that, what we can calculate is the amount of information that a self-aware being does exchange, and compare that to the amount of information that could conceivably be mutually exchanged by cosmic entities on various scales. The conclusion is that whilethe... more »

"Are we all just brain cells in a larger creature, on a planetary scale, that has yet to become self-aware? How would we know? How could we test this?"

The analogies between small-scale, living things and large-scale, cosmic entities are abundant: between a neuron and the Universe’s large-scale structure; between an atom and a solar system; between the stars in a galaxy and the atoms in a cell; between the cells in a living being and the galaxies in the Universe. It makes you wonder if, on a cosmic scale, some portion (or the whole) of the Universe could actually be alive and self-aware?
While we don’t yet know how to test for that, what we can calculate is the amount of information that a self-aware being does exchange, and compare that to the amount of information that could conceivably be mutually exchanged by cosmic entities on various scales. The conclusion is that while the entire Universe can’t do it, on timescales much longer than the present age of the Universe, individual bound galaxies, groups and clusters perhaps could.___

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2016-01-22 16:48:37 (17 comments; 5 reshares; 26 +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 — much like String Theory — it has some big problems: it doesn’t predict anything we either have observed and can’t explain without it, and it doesn’t predict anything definitive we can go and look for."

When people use the word theory colloquially, they use it to mean an “idea” or a “possibility” that could conceivably be at play. But a scientific theory has a much more stringent set of things it must accomplish: it must encompass all the successes of the previously leading theory, it must make successfulpredictions for phenomena... 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 — much like String Theory — it has some big problems: it doesn’t predict anything we either have observed and can’t explain without it, and it doesn’t predict anything definitive we can go and look for."

When people use the word theory colloquially, they use it to mean an “idea” or a “possibility” that could conceivably be at play. But a scientific theory has a much more stringent set of things it must accomplish: it must encompass all the successes of the previously leading theory, it must make successful predictions for phenomena that the leading theory cannot make, and it must predict additional, novel phenomena that can be either validated or refuted. So, is the Multiverse a scientific theory? It arises as a consequence of a scientific theory, but it fails on the grounds of making successful and novel predictions. While it might someday rise to the status of a scientific theory, it isn’t there today.___

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2016-01-21 17:11:54 (6 comments; 2 reshares; 17 +1s)Open 

"Don’t be fooled into thinking that this galaxy is either the farthest one in existence or the farthest one we’ll ever see. We’re seeing the easiest galaxies at this distance that our equipment and the Unvierse allows us to see: the ones that have the least neutral, light-blocking gas, the ones that are the biggest and brightest, and the ones that our instruments are sensitive to."

The farther away we look in the Universe, the farther back in time we look as well, since light has a finite speed. But if a galaxy’s light takes a million years to reach you, that galaxy is going to be farther away than a million light years by time that light arrives, because the fabric of the Universe itself is expanding. This leads to a puzzling fact of nature: even though the Universe is 13.8 billion years old (since the Big Bang), the most distant galaxies are upwards of 30 billion light yearsaway, w... more »

"Don’t be fooled into thinking that this galaxy is either the farthest one in existence or the farthest one we’ll ever see. We’re seeing the easiest galaxies at this distance that our equipment and the Unvierse allows us to see: the ones that have the least neutral, light-blocking gas, the ones that are the biggest and brightest, and the ones that our instruments are sensitive to."

The farther away we look in the Universe, the farther back in time we look as well, since light has a finite speed. But if a galaxy’s light takes a million years to reach you, that galaxy is going to be farther away than a million light years by time that light arrives, because the fabric of the Universe itself is expanding. This leads to a puzzling fact of nature: even though the Universe is 13.8 billion years old (since the Big Bang), the most distant galaxies are upwards of 30 billion light years away, with the current record sure to be broken in the coming years.___

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2016-01-20 20:36:00 (7 comments; 9 reshares; 55 +1s)Open 

"It’s amazing that these objects — small worlds — of the outer Solar System are found aligned so particularly. It’s even more amazing that a single explanation, a massive, larger-than-Earth planet out beyond any other world ever detected, could explain them all. But it’s a big minus that two other classes of objects should exist in this scenario that have either no or unconvincing evidence, and that the theoretical cause of these objects, the ninth planet, hasn’t been spotted at all."

Earlier today, the team of Pluto-killer Mike Brown and Konstantin Batygin announced that they had found evidence of a ninth planet in our Solar System beyond the orbit of Pluto, larger and more massive than even Earth. However, a closer inspection of the work shows that they predict a few things that haven’t been observed, including a population of Kuiper belt objects with large inclinationsand retrograd... more »

"It’s amazing that these objects — small worlds — of the outer Solar System are found aligned so particularly. It’s even more amazing that a single explanation, a massive, larger-than-Earth planet out beyond any other world ever detected, could explain them all. But it’s a big minus that two other classes of objects should exist in this scenario that have either no or unconvincing evidence, and that the theoretical cause of these objects, the ninth planet, hasn’t been spotted at all."

Earlier today, the team of Pluto-killer Mike Brown and Konstantin Batygin announced that they had found evidence of a ninth planet in our Solar System beyond the orbit of Pluto, larger and more massive than even Earth. However, a closer inspection of the work shows that they predict a few things that haven’t been observed, including a population of Kuiper belt objects with large inclinations and retrograde orbits, long-period Kuiper belt objects with opposite ecliptic latitudes and longitudes, and infrared data showing the emission from such an outer world. There are many good reasons to be skeptical, and not conclude that there’s a ninth planet without more (and better) evidence.___

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2016-01-20 17:02:26 (2 comments; 1 reshares; 23 +1s)Open 

"Since their result is close to the expected value, they assume they must have done things correctly. This confirmation bias is something we all have, and can happen with the most experienced researchers. Historically this has been seen with things like the charge of an electron or the speed of light, where the initial experimental results were a bit off, and subsequent values tended to agree with earlier results more than the current values."

The history of science is rife with stories of cases where a person or team, usually with a lot of clout, reached a conclusion that seemed incontrovertible. When that occurs, we often find that subsequent measurements agree with that conclusion, even if that conclusion later turns out to be wrong. This was the case for measurements of the speed of light and for the various masses of fundamental and composite particles during most of the 20th... more »

"Since their result is close to the expected value, they assume they must have done things correctly. This confirmation bias is something we all have, and can happen with the most experienced researchers. Historically this has been seen with things like the charge of an electron or the speed of light, where the initial experimental results were a bit off, and subsequent values tended to agree with earlier results more than the current values."

The history of science is rife with stories of cases where a person or team, usually with a lot of clout, reached a conclusion that seemed incontrovertible. When that occurs, we often find that subsequent measurements agree with that conclusion, even if that conclusion later turns out to be wrong. This was the case for measurements of the speed of light and for the various masses of fundamental and composite particles during most of the 20th century. Could that also be the case for cosmology, and in particular for cosmological parameters like dark matter, dark energy and the expansion rate of the Universe? No, and Brian Koberlein has the answer as to why.___

2016-01-19 18:07:06 (0 comments; 0 reshares; 12 +1s)Open 

A new review of my book, "Beyond The Galaxy," is in, this time from professor Pauline Barmby. Here's the clincher of a quote:

"Beyond the Galaxy is up-to-date, engaging, and written by someone who clearly has a lot of experience explaining cosmological topics to the non-specialist. I’d recommend it for the interested member of the public who wants to go beyond the one-hour public lecture by a scientist or a 30-second news story: this book delivers on its promise to give the whole story of modern cosmology."

Go read the whole thing, and thanks, Pauline! 

A new review of my book, "Beyond The Galaxy," is in, this time from professor Pauline Barmby. Here's the clincher of a quote:

"Beyond the Galaxy is up-to-date, engaging, and written by someone who clearly has a lot of experience explaining cosmological topics to the non-specialist. I’d recommend it for the interested member of the public who wants to go beyond the one-hour public lecture by a scientist or a 30-second news story: this book delivers on its promise to give the whole story of modern cosmology."

Go read the whole thing, and thanks, Pauline! ___

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2016-01-18 22:40:02 (0 comments; 5 reshares; 16 +1s)Open 

"The Chamaeleon and Corona Australis molecular clouds are closest at ~500 light years, while just under 600 light years distant, the Lupus clouds lie in the constellation of the wolf. In visible light, these clouds appear predominantly as dark patches, obscuring and reddening the light of background stars. In the infrared, though, the gas glows brilliantly as it forms new stars inside."

If you ask the average person where you can find new stars in our galaxy, they might (correctly) identify the Orion Nebula, a hotbed of star formation where thousands of new stars are presently being born. But at ~1,500 light years away, it’s not the closest place where new stars are forming, not by a long shot. Instead, the southern hemisphere holds a number of smaller “dark nebulae,” which are actually gas clouds. Many of them are in the process of forming brilliant new stars, including Lupus 3,which... more »

"The Chamaeleon and Corona Australis molecular clouds are closest at ~500 light years, while just under 600 light years distant, the Lupus clouds lie in the constellation of the wolf. In visible light, these clouds appear predominantly as dark patches, obscuring and reddening the light of background stars. In the infrared, though, the gas glows brilliantly as it forms new stars inside."

If you ask the average person where you can find new stars in our galaxy, they might (correctly) identify the Orion Nebula, a hotbed of star formation where thousands of new stars are presently being born. But at ~1,500 light years away, it’s not the closest place where new stars are forming, not by a long shot. Instead, the southern hemisphere holds a number of smaller “dark nebulae,” which are actually gas clouds. Many of them are in the process of forming brilliant new stars, including Lupus 3, which is giving birth to stars ranging from much less than the mass of our Sun all the way up to many times it mass and brightness.___

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2016-01-18 16:23:19 (4 comments; 7 reshares; 40 +1s)Open 

"We’ve often found that — when it comes to unexpected astronomical signals — our imaginations run away with us, leading us to immediately jump to conclusions about our greatest hopes and/or fears, like the existence of sentient aliens accessible to us. But the real Universe, every time thus far, has shown itself to be more diverse, complex, and rich in phenomena than we had previously realized, including the existence of quasars, pulsars, exoplanets and more. We haven’t yet ruled out the possibility of alien megastructures, but what we’re most likely seeing is a new type of natural phenomena whose origin is yet unknown. Follow-up observations, particularly those scheduled for 2017, when another major “transit” event is scheduled to occur, should teach us a whole lot more."

Last year, Penn State astronomer Jason Wright made headlines by claiming that one of the stars beingobserved by N... more »

"We’ve often found that — when it comes to unexpected astronomical signals — our imaginations run away with us, leading us to immediately jump to conclusions about our greatest hopes and/or fears, like the existence of sentient aliens accessible to us. But the real Universe, every time thus far, has shown itself to be more diverse, complex, and rich in phenomena than we had previously realized, including the existence of quasars, pulsars, exoplanets and more. We haven’t yet ruled out the possibility of alien megastructures, but what we’re most likely seeing is a new type of natural phenomena whose origin is yet unknown. Follow-up observations, particularly those scheduled for 2017, when another major “transit” event is scheduled to occur, should teach us a whole lot more."

Last year, Penn State astronomer Jason Wright made headlines by claiming that one of the stars being observed by NASA’s Kepler mission might contain alien megastructures around it. The large dips in its light curve didn’t make sense in the context of planets, and the star KIC 8462852 became the target of a great many follow-ups. A binary companion was found, along with no signs of excess infrared emission or artificial radio signatures. However, archival data recently found that the star dimmed by about 20% over the past century. While the alien megastructures possibility cannot be ruled out, a great many other astrophysical possibilities still survive.___

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2016-01-17 16:54:56 (6 comments; 5 reshares; 30 +1s)Open 

"What we’re left with is an observable Universe that’s huge: 46 billion light years in radius, containing some 10^12 galaxies, 10^24 stars, 10^80 atoms and nearly 10^90 photons. But those numbers, while astronomical, are finite, and don’t give us any information about what happened in the Universe prior to the last tiny-fraction-of-a-second of inflation. We can do theoretical calculations to attempt to gain some insight, but they’re all model dependent. With the exception of a few specific models that would leave observable traces in our Universe (most don’t), we have no way of knowing how — or even if — the Universe got its start."

As we peel back the layers of information deeper and deeper into the Universe’s history, we uncover progressively more knowledge about how everything we know today came to be. The discovery of distant galaxies and their redshifts led toexpanding Unive... more »

"What we’re left with is an observable Universe that’s huge: 46 billion light years in radius, containing some 10^12 galaxies, 10^24 stars, 10^80 atoms and nearly 10^90 photons. But those numbers, while astronomical, are finite, and don’t give us any information about what happened in the Universe prior to the last tiny-fraction-of-a-second of inflation. We can do theoretical calculations to attempt to gain some insight, but they’re all model dependent. With the exception of a few specific models that would leave observable traces in our Universe (most don’t), we have no way of knowing how — or even if — the Universe got its start."

As we peel back the layers of information deeper and deeper into the Universe’s history, we uncover progressively more knowledge about how everything we know today came to be. The discovery of distant galaxies and their redshifts led to expanding Universe, which led to the Big Bang and the discovery of very early phases like the cosmic microwave background and big bang nucleosynthesis. But before that, there was a period of cosmic inflation that left its mark on the Universe. What came before inflation, then? Did it always exist? Did it have a beginning? Or did it mark the rebirth of a cosmic cycle? Maddeningly, this information may forever be inaccessible to us, as the nature of inflation wipes all this information clean from our visible Universe.___

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2016-01-16 15:55:38 (3 comments; 2 reshares; 15 +1s)Open 

"We evolved to be killers, meat-eaters and rapists, among other things. We evolved to survive and reproduce. But that is not the world we’ve built as a society, and in a great many ways, we no longer engage in the basest of our biological urges when they’re harmful to society. That’s why we have laws and a society in the first place.

Your evolutionary nature is no excuse for your behavior; your behavior is defined by your choices, which is influenced by your urges and your nature, but not determined by them."

From nuclear bomb testing (it wasn't an H-bomb) to the science of should you play Powerball to harassment in astronomy and much, much more, it was an incredibly busy week here at Starts With A Bang. Don't miss the best of it and catch up on all the follow-ups on this edition of our Comments of the Week!

"We evolved to be killers, meat-eaters and rapists, among other things. We evolved to survive and reproduce. But that is not the world we’ve built as a society, and in a great many ways, we no longer engage in the basest of our biological urges when they’re harmful to society. That’s why we have laws and a society in the first place.

Your evolutionary nature is no excuse for your behavior; your behavior is defined by your choices, which is influenced by your urges and your nature, but not determined by them."

From nuclear bomb testing (it wasn't an H-bomb) to the science of should you play Powerball to harassment in astronomy and much, much more, it was an incredibly busy week here at Starts With A Bang. Don't miss the best of it and catch up on all the follow-ups on this edition of our Comments of the Week!___

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2016-01-16 15:44:57 (0 comments; 5 reshares; 31 +1s)Open 

"A gravitational ripple must also travel through the expanding Universe, will also travel at the speed of light through space (whether that space is expanding, contracting or static), and will have its wavelength stretched the exact same way photons have theirs stretched. Gravitational waves “ride” the fabric of space the same way water waves “ride” the surface of the water; if you have a rock fall into a river, the ripples don’t just move radially outward; they move outward and get carried by the current downstream."

When Einstein’s theory was first proposed as an alternative to Newtonian gravity, there were a number of subtle but important theoretical differences noted between the two. Einstein’s theory predicted gravitational redshift, time delays, bending of light and more. But what was perhaps most remarkable is that unlike Newton’s gravity, Einstein’s generalrelativity predic... more »

"A gravitational ripple must also travel through the expanding Universe, will also travel at the speed of light through space (whether that space is expanding, contracting or static), and will have its wavelength stretched the exact same way photons have theirs stretched. Gravitational waves “ride” the fabric of space the same way water waves “ride” the surface of the water; if you have a rock fall into a river, the ripples don’t just move radially outward; they move outward and get carried by the current downstream."

When Einstein’s theory was first proposed as an alternative to Newtonian gravity, there were a number of subtle but important theoretical differences noted between the two. Einstein’s theory predicted gravitational redshift, time delays, bending of light and more. But what was perhaps most remarkable is that unlike Newton’s gravity, Einstein’s general relativity predicted an entirely new phenomenon: gravitational radiation. Much like how charged particles moving in a magnetic field accelerate and emit radiation in the form of photons, masses moving in a gravitational field accelerate and emit radiation in the form of gravitational waves, or ripples in the fabric of space itself. Even though these waves move at c, the speed of light in a vacuum, the expanding Universe carries them even farther, as these ripples ride atop the fabric of our expanding spacetime.___

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2016-01-15 16:15:32 (6 comments; 2 reshares; 24 +1s)Open 

"The real story — the one you’re only seeing the beginning of — is that for the first time, these actions are getting the attention they deserve for what they truly are: unacceptable. A senior scientist’s right to control the fate, behavior, personal space and even the bodies of junior scientists is no longer going to fly. Creating a work environment that’s comfortable for some and less accessible to others based on gender, race, sexual orientation or identity has been the norm for a very long time, but all of that is changing."

Geoff Marcy. Tim Slater. Christian Ott. And a great many more who are just waiting to be publicly exposed for what they’ve done (and in many cases, are still doing). Does it mean that astronomy has a harassment problem? Of course it does, but that’s not the real story. The real story is that, for the first time, an entire academic field isrecognizing a... more »

"The real story — the one you’re only seeing the beginning of — is that for the first time, these actions are getting the attention they deserve for what they truly are: unacceptable. A senior scientist’s right to control the fate, behavior, personal space and even the bodies of junior scientists is no longer going to fly. Creating a work environment that’s comfortable for some and less accessible to others based on gender, race, sexual orientation or identity has been the norm for a very long time, but all of that is changing."

Geoff Marcy. Tim Slater. Christian Ott. And a great many more who are just waiting to be publicly exposed for what they’ve done (and in many cases, are still doing). Does it mean that astronomy has a harassment problem? Of course it does, but that’s not the real story. The real story is that, for the first time, an entire academic field is recognizing a widespread problem, taking steps to change its policies, and is beginning to support the victims, rather than the senior, more famous, more prestigious perpetrators. Astronomy is the just start; hopefully physics, computer science, engineering, philosophy and economics are next.___

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2016-01-14 22:04:31 (14 comments; 4 reshares; 19 +1s)Open 

"The most exciting aspect of 21cm astronomy is that it does not only give us a snapshot at one particular moment – like the CMB – but allows us to continuously map different epochs during the dark ages. By measuring the red-shifted photons at different wavelengths, we can scan through the entire time period. This would give us many new insights about the history of our universe."

From the time that neutral atoms first formed in the Universe (the creation of the CMB) until the first stars formed, perhaps 100 million years passed. Yet these “dark ages” weren’t truly devoid of light; the very faint signal of hydrogen atoms flipping their spin and emitting 21cm radiation filled the Universe. That radiation, if we build sensitive enough detectors, ought to be visible to us today at incredibly long wavelengths. With the potential to map out reionization, neutral gas, dark matter andeven netw... more »

"The most exciting aspect of 21cm astronomy is that it does not only give us a snapshot at one particular moment – like the CMB – but allows us to continuously map different epochs during the dark ages. By measuring the red-shifted photons at different wavelengths, we can scan through the entire time period. This would give us many new insights about the history of our universe."

From the time that neutral atoms first formed in the Universe (the creation of the CMB) until the first stars formed, perhaps 100 million years passed. Yet these “dark ages” weren’t truly devoid of light; the very faint signal of hydrogen atoms flipping their spin and emitting 21cm radiation filled the Universe. That radiation, if we build sensitive enough detectors, ought to be visible to us today at incredibly long wavelengths. With the potential to map out reionization, neutral gas, dark matter and even networks of cosmic strings, 21cm astronomy has the potential to fill in the greatest missing gap in our understanding of the Universe. By +Sabine Hossenfelder.___

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2016-01-14 18:57:16 (0 comments; 0 reshares; 15 +1s)Open 

Did you catch your favorite theoretical astrophysicist on Portland's news last night, talking about the biggest discoveries of 2016 so far, the highlights of the annual American Astronomical Society meeting, North Korea's nuclear test and the great hope for a new type of astronomy later this year?

Catch it now, and welcome to the start of 2016 in the Universe!

Did you catch your favorite theoretical astrophysicist on Portland's news last night, talking about the biggest discoveries of 2016 so far, the highlights of the annual American Astronomical Society meeting, North Korea's nuclear test and the great hope for a new type of astronomy later this year?

Catch it now, and welcome to the start of 2016 in the Universe!___

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2016-01-13 23:51:16 (1 comments; 2 reshares; 8 +1s)Open 

So, I heard you didn't just want my book, but that you wanted a copy autographed and shipped anywhere in the world, immediately, for your own consumption? (Or, perhaps, as a gift for the right person in your life?)

Here's how!

So, I heard you didn't just want my book, but that you wanted a copy autographed and shipped anywhere in the world, immediately, for your own consumption? (Or, perhaps, as a gift for the right person in your life?)

Here's how!___

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2016-01-13 15:09:28 (9 comments; 3 reshares; 19 +1s)Open 

"What’s crazy — and unintuitive — is that as the Jackpot rises higher and higher, because more and more tickets get sold, the less valuable each ticket becomes! A ticket sold for a $1,500 million (or $1.5 billion) Jackpot, in fact, would only be worth about half as much as a ticket sold for a $500 million Jackpot, because you’d most likely have to split the Jackpot, even if you won, with between three and seven other people. And that’s probably what’s going to happen tonight."

Later today, the richest lottery drawing in history — the $1.5 billion Powerball jackpot — will take place. While many outlets are encouraging people to purchase as many tickets as possible, it’s important to run through the mathematics and find out what your expected value is for each ticket. While a naive analysis shows that a jackpot in excess of about $245 million would lead to abreak-even-or-better resu... more »

"What’s crazy — and unintuitive — is that as the Jackpot rises higher and higher, because more and more tickets get sold, the less valuable each ticket becomes! A ticket sold for a $1,500 million (or $1.5 billion) Jackpot, in fact, would only be worth about half as much as a ticket sold for a $500 million Jackpot, because you’d most likely have to split the Jackpot, even if you won, with between three and seven other people. And that’s probably what’s going to happen tonight."

Later today, the richest lottery drawing in history — the $1.5 billion Powerball jackpot — will take place. While many outlets are encouraging people to purchase as many tickets as possible, it’s important to run through the mathematics and find out what your expected value is for each ticket. While a naive analysis shows that a jackpot in excess of about $245 million would lead to a break-even-or-better result, when you factor in taxes and split jackpots, you find that even for the $1.5 billion jackpot, your $2 ticket is only worth about $0.85.___

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2016-01-11 17:50:50 (4 comments; 6 reshares; 20 +1s)Open 

"Discovered by Spitzer, it was rediscovered in archival Chandra data, and then reimaged for 28 hours. Also captured by Hubble, this cluster may, by today, be the most massive one in the visible Universe."

13.8 billion years ago, the Universe as we know it was born with no stars, no clusters and no galaxies. But over time, gravitation has built up all sorts of complex structures, with the largest galaxy cluster today, El Gordo, weighing in at 3 quadrillion Suns. But back when the Universe was just a quarter of its present age, the cluster IDCS J1426.5+3508 already has a mass of 500 trillion Suns, a mass that’s been measured by three different methods. By time we fast-forward to today, this cluster is probably the most massive one contained within our visible Universe.

"Discovered by Spitzer, it was rediscovered in archival Chandra data, and then reimaged for 28 hours. Also captured by Hubble, this cluster may, by today, be the most massive one in the visible Universe."

13.8 billion years ago, the Universe as we know it was born with no stars, no clusters and no galaxies. But over time, gravitation has built up all sorts of complex structures, with the largest galaxy cluster today, El Gordo, weighing in at 3 quadrillion Suns. But back when the Universe was just a quarter of its present age, the cluster IDCS J1426.5+3508 already has a mass of 500 trillion Suns, a mass that’s been measured by three different methods. By time we fast-forward to today, this cluster is probably the most massive one contained within our visible Universe.___

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2016-01-11 03:42:02 (0 comments; 1 reshares; 24 +1s)Open 

"[J]ust because you have a magnetic field outside of your spacecraft doesn’t mean you need to have one inside. One of the great properties of electromagnetism is that it has two types of charges: positive and negative, and so unlike with gravitation, it’s possible to shield yourself (with the right electromagnetic configuration) from both electric and magnetic fields. As long as you create a more efficient path for the magnetic field lines to travel through the hull of your spacecraft (rather than through the inhabited interior) you won’t have any problems to the humans inside. I am well aware than not all of the problems associated with interstellar travel are easy to solve, but I’m pleased to inform you that this one is!"

Go to AAS for a week: check.
Write about a ton of new science: check.
Check what people have to say about it: KABOOM!

Come see whathappene... more »

"[J]ust because you have a magnetic field outside of your spacecraft doesn’t mean you need to have one inside. One of the great properties of electromagnetism is that it has two types of charges: positive and negative, and so unlike with gravitation, it’s possible to shield yourself (with the right electromagnetic configuration) from both electric and magnetic fields. As long as you create a more efficient path for the magnetic field lines to travel through the hull of your spacecraft (rather than through the inhabited interior) you won’t have any problems to the humans inside. I am well aware than not all of the problems associated with interstellar travel are easy to solve, but I’m pleased to inform you that this one is!"

Go to AAS for a week: check.
Write about a ton of new science: check.
Check what people have to say about it: KABOOM!

Come see what happened this week while I was uncovering the latest news about the Universe!___

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2016-01-09 19:56:55 (8 comments; 3 reshares; 21 +1s)Open 

"In terms of energy yield, there’s just no way the North Korean quake was caused by a fusion bomb. If it were, it would be by far the lowest energy, most efficient fusion reaction ever created on the planet, and done so in a way that even theorists are uncertain how it could occur.
[...]
In other words, all the data we have is pointing to one conclusion: the result of this nuclear test is that we have a fission reaction taking place, with no hint of a fusion reaction. My hunch is that this was intended to be a fusion reaction; perhaps there was a second-or-third stage intended to this bomb that would have resulted in the fusion of hydrogen into helium, but that part of the bomb was a dud."

The news has been aflame with reports that North Korea detonated a hydrogen bomb on January 6th, greatly expanding its nuclear capabilities with their fourth nuclear test and the potentialt... more »

"In terms of energy yield, there’s just no way the North Korean quake was caused by a fusion bomb. If it were, it would be by far the lowest energy, most efficient fusion reaction ever created on the planet, and done so in a way that even theorists are uncertain how it could occur.
[...]
In other words, all the data we have is pointing to one conclusion: the result of this nuclear test is that we have a fission reaction taking place, with no hint of a fusion reaction. My hunch is that this was intended to be a fusion reaction; perhaps there was a second-or-third stage intended to this bomb that would have resulted in the fusion of hydrogen into helium, but that part of the bomb was a dud."

The news has been aflame with reports that North Korea detonated a hydrogen bomb on January 6th, greatly expanding its nuclear capabilities with their fourth nuclear test and the potential to carry out a devastating strike against either South Korea or, if they’re more ambitious, the United States. The physics of what a nuclear explosion actually does and how that signal propagates through the air, oceans and ground, however, can tell us whether this was truly a nuclear detonation at all, and if so, whether it was fusion or fission. From all the data we’ve collected, this appears to be nothing new: just a run-of-the-mill fission bomb, with the rest being a sensationalized claim.___

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2016-01-08 22:35:30 (0 comments; 4 reshares; 27 +1s)Open 

"We’ve done a great job mapping the galactic plane, which was a tremendous achievement given that you can’t see through the interstellar dust in the optical. But you can in the infrared, and we’ve done that not only with WISE, but with the much higher-resolution (and higher-energy) Spitzer Space Telescope, which has mapped the entire Milky Way galaxy. Yet of all the sources we’ve discovered, here’s a fun find in the new Fermi data: an unknown source of gamma rays!"

With the launch of the Fermi satellite in the late 2000s, we began observing the highest energy photons in the Universe — gamma rays — all over the sky, to unprecedented precision. Produced from cosmic ray showers in space when high energy protons run into other, stationary protons, these gamma rays locate point sources from supermassive black holes to supernova remnants to pulsars. There is, additionally, agreat correla... more »

"We’ve done a great job mapping the galactic plane, which was a tremendous achievement given that you can’t see through the interstellar dust in the optical. But you can in the infrared, and we’ve done that not only with WISE, but with the much higher-resolution (and higher-energy) Spitzer Space Telescope, which has mapped the entire Milky Way galaxy. Yet of all the sources we’ve discovered, here’s a fun find in the new Fermi data: an unknown source of gamma rays!"

With the launch of the Fermi satellite in the late 2000s, we began observing the highest energy photons in the Universe — gamma rays — all over the sky, to unprecedented precision. Produced from cosmic ray showers in space when high energy protons run into other, stationary protons, these gamma rays locate point sources from supermassive black holes to supernova remnants to pulsars. There is, additionally, a great correlation between the infrared sky and the gamma ray sky, since the great high-energy background scatters off of the diffuse infrared gas, producing gamma rays there as well. But while a great many sources can be correlated with known structures, Fermi reveals at least one unknown, intense behemoth that emits spectacularly in gamma rays.___

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2016-01-07 17:46:02 (5 comments; 2 reshares; 20 +1s)Open 

"[I]f the measured value for n_s stays what it’s thought to be right now, and after a decade we’ve constrained r < 10-3, then the simplest models for inflation are all wrong. It doesn’t mean inflation is wrong, but it means inflation is something more complicated than we first thought, and perhaps not even a scalar field at all.

If nature is unkind to us, the last great prediction of cosmic inflation — the existence of primordial gravitational waves — will be elusive to us for many decades to come, and will continue to go unconfirmed."

Cosmic inflation, our earliest theory of the Universe and the phenomenon that sets up the Big Bang, didn’t just explain a number of puzzles, but made a slew of new predictions for the Universe. In the subsequent 35 years, five of the six have been confirmed, with only primordial gravitational waves left to go. Inflation predictsthat they c... more »

"[I]f the measured value for n_s stays what it’s thought to be right now, and after a decade we’ve constrained r < 10-3, then the simplest models for inflation are all wrong. It doesn’t mean inflation is wrong, but it means inflation is something more complicated than we first thought, and perhaps not even a scalar field at all.

If nature is unkind to us, the last great prediction of cosmic inflation — the existence of primordial gravitational waves — will be elusive to us for many decades to come, and will continue to go unconfirmed."

Cosmic inflation, our earliest theory of the Universe and the phenomenon that sets up the Big Bang, didn’t just explain a number of puzzles, but made a slew of new predictions for the Universe. In the subsequent 35 years, five of the six have been confirmed, with only primordial gravitational waves left to go. Inflation predicts that they could be large or small, but based on the simplest classes of models and the measured value of the density fluctuations, the gravitational waves must, according to cosmologist Mark Kamionkowski, be within the range of telescopes during the next decade. If we find them, either one of the two simplest models could be correct, but if we don’t, then the two simplest classes of inflationary models are all wrong, and gravitational waves from inflation may be invisible to us for the foreseeable future.___

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2016-01-06 21:03:43 (0 comments; 8 reshares; 28 +1s)Open 

"As first released this week at the American Astronomical Society’s annual meeting, Kepler-56 appears to have a third planet orbiting it — about six times the mass of Jupiter with a period of around three Earth-years — thanks to the work of Justin Otor, Benjamin Montet and John A. Johnson."

When a planet passes in front of its star from our point of view, that transiting phenomenon can be detected as a dip in starlight. By surveying some 150,000 stars, the Kepler mission has detected close to 10,000 planetary candidates, many of which have been identified by the stellar wobble technique. But this “wobbling” also sometimes contain rising or falling trend lines, which can indicate a more massive, outer world orbiting the central star. Even though Kepler could normally never detect some of these planets, since their baseline time is so long and their likelihood of transits arelower, th... more »

"As first released this week at the American Astronomical Society’s annual meeting, Kepler-56 appears to have a third planet orbiting it — about six times the mass of Jupiter with a period of around three Earth-years — thanks to the work of Justin Otor, Benjamin Montet and John A. Johnson."

When a planet passes in front of its star from our point of view, that transiting phenomenon can be detected as a dip in starlight. By surveying some 150,000 stars, the Kepler mission has detected close to 10,000 planetary candidates, many of which have been identified by the stellar wobble technique. But this “wobbling” also sometimes contain rising or falling trend lines, which can indicate a more massive, outer world orbiting the central star. Even though Kepler could normally never detect some of these planets, since their baseline time is so long and their likelihood of transits are lower, the inner worlds that Kepler can find, when we subject them to verification, can sometimes reveal the presence of an outer, massive world. A new record for the longest-period planet ever found as the result of Kepler was just set: 1000 days, with a mass of around six Jupiter masses.___

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2016-01-05 12:33:28 (5 comments; 8 reshares; 74 +1s)Open 

"The “wobble” meant that the star moved back-and-forth by an extra speed of just 0.0005 km/s every 3.24 days. And it was measured over a long enough baseline that other explanations — internal magnetic properties of the star, instrumental noise, or the tug of other companion stars — couldn’t be the cause. It seemed they had truly discovered a planet."

In 2012, astronomers announced that the nearest star system to us, the Alpha Centauri system, possessed at least one exoplanet around it. A periodic signal that recurred just every 3.24 days was consistent with an Earth-sized exoplanet orbiting and gravitationally tugging on the second largest member of the star system: Alpha Centauri B. That planet, named Alpha Centauri Bb, turns out not to actually be there. A reanalysis of the data shows that a combination of stellar properties and the times at which the observations were madeconspired... more »

"The “wobble” meant that the star moved back-and-forth by an extra speed of just 0.0005 km/s every 3.24 days. And it was measured over a long enough baseline that other explanations — internal magnetic properties of the star, instrumental noise, or the tug of other companion stars — couldn’t be the cause. It seemed they had truly discovered a planet."

In 2012, astronomers announced that the nearest star system to us, the Alpha Centauri system, possessed at least one exoplanet around it. A periodic signal that recurred just every 3.24 days was consistent with an Earth-sized exoplanet orbiting and gravitationally tugging on the second largest member of the star system: Alpha Centauri B. That planet, named Alpha Centauri Bb, turns out not to actually be there. A reanalysis of the data shows that a combination of stellar properties and the times at which the observations were made conspired to produce this spurious signal: a signal that goes away if the data is handled correctly. Accounting for everything correctly reveals something else of interest, a periodic 20-day signal, which may turn out — with better observations — to be Alpha Centauri’s first exoplanet after all.___

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2016-01-04 13:39:40 (3 comments; 1 reshares; 16 +1s)Open 

“But a careful analysis of the data showed that while the outer arcs are indeed lensed background galaxies, the brightest blue lights, interconnecting the two giant ellipticals at the cluster's center, come from the merger of the galaxies and the surrounding gas themselves. What we're looking at is a combination of the stars and galaxies of the foregrounds cluster, some 4,000 times as massive as the Milky Way, a transient burst of star formation, and only a few background objects.”

One of the most spectacular predictions of Einstein's General Relativity was the existence of gravitational lensing, whereby a large foreground mass could act as a lens, magnifying and distorting the background light source behind it. Although this was first observed for quasars, large galaxy clusters act as the most powerful lenses. Which is why it was such a surprise that the brightest feature in therec... more »

“But a careful analysis of the data showed that while the outer arcs are indeed lensed background galaxies, the brightest blue lights, interconnecting the two giant ellipticals at the cluster's center, come from the merger of the galaxies and the surrounding gas themselves. What we're looking at is a combination of the stars and galaxies of the foregrounds cluster, some 4,000 times as massive as the Milky Way, a transient burst of star formation, and only a few background objects.”

One of the most spectacular predictions of Einstein's General Relativity was the existence of gravitational lensing, whereby a large foreground mass could act as a lens, magnifying and distorting the background light source behind it. Although this was first observed for quasars, large galaxy clusters act as the most powerful lenses. Which is why it was such a surprise that the brightest feature in the recently observed galaxy cluster SDSS J1531+3414 wasn't from gravitational lensing, as originally thought, but was simply a gas bridge of star formation connecting two giant elliptical galaxies. It took redshift data for the individual components to arrive at that conclusion, showing once again that even the best experience and intuition is no substitute for good data.___

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2016-01-03 00:34:43 (9 comments; 2 reshares; 28 +1s)Open 

"[I]f there were antimatter galaxies out there, then there should be some interface between the matter and antimatter ones. Either there would be a discontinuity (like a domain wall) separating the two regions, there would be an interface where gamma rays of a specific frequency originated, or there would be a great 2D void where it’s all already annihilated away.

And our Universe contains none of these things. The absence of them in all directions and in all locations tells us that if there are antimatter galaxies out there, they’re far beyond the observable part of our Universe. Instead, every interacting pair we see shows evidence that they’re all made of matter. Beautiful, beautiful matter."

There's no better way to start 2016 than... with a bang! Come check out our first comments of the week of the new year.

"[I]f there were antimatter galaxies out there, then there should be some interface between the matter and antimatter ones. Either there would be a discontinuity (like a domain wall) separating the two regions, there would be an interface where gamma rays of a specific frequency originated, or there would be a great 2D void where it’s all already annihilated away.

And our Universe contains none of these things. The absence of them in all directions and in all locations tells us that if there are antimatter galaxies out there, they’re far beyond the observable part of our Universe. Instead, every interacting pair we see shows evidence that they’re all made of matter. Beautiful, beautiful matter."

There's no better way to start 2016 than... with a bang! Come check out our first comments of the week of the new year.___

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2016-01-02 16:40:23 (13 comments; 3 reshares; 29 +1s)Open 

"Do you think interstellar travel is possible (by any civilization). It seems to me that all possible solutions are one way trips."

The stars call to us through the ages, with each and every one holding the promise of a future for humanity beyond Earth. For generations, this was a mere dream, as our technology allowed us to neither know what worlds might lie beyond our own Solar System or to reach beyond our planet. But time and development has changed both of those things significantly. Now, when we look to the stars, we know that potentially habitable worlds lurk throughout our galaxy, and our spaceflight capabilities can bring us there. But so far, it would only be a very long, lonely, one-way trip. This isn’t necessarily going to be the case forever, though, as physically feasible technology could get humans to another star within a single lifetime, and potentially groundbreakingt... more »

"Do you think interstellar travel is possible (by any civilization). It seems to me that all possible solutions are one way trips."

The stars call to us through the ages, with each and every one holding the promise of a future for humanity beyond Earth. For generations, this was a mere dream, as our technology allowed us to neither know what worlds might lie beyond our own Solar System or to reach beyond our planet. But time and development has changed both of those things significantly. Now, when we look to the stars, we know that potentially habitable worlds lurk throughout our galaxy, and our spaceflight capabilities can bring us there. But so far, it would only be a very long, lonely, one-way trip. This isn’t necessarily going to be the case forever, though, as physically feasible technology could get humans to another star within a single lifetime, and potentially groundbreaking technology might make the journey almost instantaneous.___

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2016-01-01 22:12:34 (9 comments; 30 reshares; 94 +1s)Open 

"1960s — After some 20 years of debate, the key observation that would decide the history of the Universe was uncovered: the discovery of the predicted leftover glow from the Big Bang, or the Cosmic Microwave Background. This uniform, 2.725 K radiation was discovered in 1965 by Arno Penzias and Bob Wilson, neither of whom realized what they had discovered at first. Yet over time, the full, blackbody spectrum of this radiation and even its fluctuations were measured, showing us that the Universe started with a “bang” after all."

Considering what we know about our Universe today, it’s hard to believe that just a century ago, Einstein’s General Relativity was very much untested and uncertain, and we hadn’t even realized that anything at all lie outside our own Milky Way. But over the past ten decades, ten great discoveries have taken place to give us the Universe we understandtoday.
more »

"1960s — After some 20 years of debate, the key observation that would decide the history of the Universe was uncovered: the discovery of the predicted leftover glow from the Big Bang, or the Cosmic Microwave Background. This uniform, 2.725 K radiation was discovered in 1965 by Arno Penzias and Bob Wilson, neither of whom realized what they had discovered at first. Yet over time, the full, blackbody spectrum of this radiation and even its fluctuations were measured, showing us that the Universe started with a “bang” after all."

Considering what we know about our Universe today, it’s hard to believe that just a century ago, Einstein’s General Relativity was very much untested and uncertain, and we hadn’t even realized that anything at all lie outside our own Milky Way. But over the past ten decades, ten great discoveries have taken place to give us the Universe we understand today.

Complete with the Big Bang, dark matter, dark energy, cosmic inflation and so much more, one can’t help but wonder what the current decade — or even the coming decades — might hold to open up our understanding of the Universe even further.___

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2015-12-31 21:04:47 (6 comments; 8 reshares; 41 +1s)Open 

"This is right at the frontiers of what is known, and is my bet for the next of the greatest unsolved problems in theoretical physics to fall. With any luck, we’ll finally be able to explain why there’s more matter than antimatter in our Universe very soon."

Everywhere we look in the Universe, we find that planets, stars, galaxies, and even the gas between them are all made of matter and not antimatter. Yet as far as we know, the laws of nature are symmetric between matter and antimatter: you can’t create or destroy one without the other. This question — why the Universe is full of matter and not antimatter — is one of the greatest unsolved problems in theoretical physics. Yet it’s also, conceivably, the one most likely to fall in the coming year! There are four compelling scenarios that might solve this question, that of baryogenesis, that theoretical physics has uncovered,and there’s... more »

"This is right at the frontiers of what is known, and is my bet for the next of the greatest unsolved problems in theoretical physics to fall. With any luck, we’ll finally be able to explain why there’s more matter than antimatter in our Universe very soon."

Everywhere we look in the Universe, we find that planets, stars, galaxies, and even the gas between them are all made of matter and not antimatter. Yet as far as we know, the laws of nature are symmetric between matter and antimatter: you can’t create or destroy one without the other. This question — why the Universe is full of matter and not antimatter — is one of the greatest unsolved problems in theoretical physics. Yet it’s also, conceivably, the one most likely to fall in the coming year! There are four compelling scenarios that might solve this question, that of baryogenesis, that theoretical physics has uncovered, and there’s a good chance that the LHC’s run II will be sensitive to two of them.

Also, don't forget to check out my new podcast on this subject, at the end of the post or (directly) here: https://soundcloud.com/ethan-siegel-172073460/starts-with-a-bang-3-why-is-there-more-matter-than-antimatter___

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2015-12-31 17:26:10 (3 comments; 0 reshares; 17 +1s)Open 

"In short, Ethan’s book is the missing link between cosmology textbooks and popular science articles. It will ease your transition if you are attempting one, or, if that is not your intention, it will serve to tie together the patchy knowledge that news articles often leave us with. It is the ideal starting point if you want to get serious about digging into cosmology, or if you are just dissatisfied by the vagueness of much contemporary science writing."

When this comes from Backreaction and +Sabine Hossenfelder -- who never 100% likes any book without a ton of caveats -- this is definitely high praise!

"In short, Ethan’s book is the missing link between cosmology textbooks and popular science articles. It will ease your transition if you are attempting one, or, if that is not your intention, it will serve to tie together the patchy knowledge that news articles often leave us with. It is the ideal starting point if you want to get serious about digging into cosmology, or if you are just dissatisfied by the vagueness of much contemporary science writing."

When this comes from Backreaction and +Sabine Hossenfelder -- who never 100% likes any book without a ton of caveats -- this is definitely high praise!___

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