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Ethan Siegel
Works at NASA's The Space Place
Attended University of Florida College of Liberal Arts and Sciences
Lived in Bronx, New York
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Ethan Siegel

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"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. 
Nearly 100 years after they were predicted, gravitational waves have been directly observed for the first time. Welcome to the era of gravitational wave astronomy!
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+LBBstore Isn't this exactly what science is? These guys claim a discovery and now others need to independently confirm or dispute it. What's your problem?
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"[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.
Einstein's General Relativity predicted a whole slew of unexpected phenomena, including a new type of radiation: gravitational waves. LIGO may be about to discover them for the first time.
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Dark matter will no longer be dark. 
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""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!
“Where there is an observatory and a telescope, we expect that any eyes will see new worlds at once.” -Henry David Thoreau With more stories of the Universe having been told this past week at Starts With A Bang, it’s always a thrill to look back, see what we’ve covered and see what thoughts and ideas they’ve…
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"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.
The largest, most powerful telescopes in the world today are between 8 and 10 meters in diameter. This proposed behemoth will change astronomy forever.
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Ethan Siegel

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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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Doesn't matter. What we are is tightly linked to the past and very loosely linked to the future. I simply can't stand salesmanship in the sciences.  Shoes an almost complete disregard for (ignorance of) the only thing that makes science unique... filtering the noise of observation, of vantage. You want to popularize science? Tell the real story. Geeky excitement is no less noisy than any other form of subjective motive.
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Ethan Siegel

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"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.
In last night's Iowa caucuses, six delegates came down to coin flips. Clinton won all six. What are the odds of that?
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It's now coming out that apparently the "Hillary winning six coin toss" story was an example of bad reporting by the media causing confusion. Apparently there were more than just six coin tosses and Sanders won some of them.
http://www.npr.org/2016/02/02/465268206/coin-toss-fact-check-no-coin-flips-did-not-win-iowa-for-hillary-clinton
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Ethan Siegel

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"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.
We've found rocky planets around stars, capable of supporting life. Next up: time to look for biosignatures. Here's how.
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"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.
If you want to gather the greatest amount of light possible, why have a hole in the center of your largest telescope mirrors?
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+James Carlson Yup, have a CPC1100 in my observatory. It's been a workhorse.
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"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.
65 million years ago, a catastrophic strike from space decimated life on Earth. Are these events regular, and are we due?
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Yep. We humans seem especially susceptible to existential escape delusions... probably the single biggest source of the noise that science must filter.
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"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.
When scientists say “the Big Bang,” they mean two possible things. But only one of them is still correct.
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Thanks.
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"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!
The densest form of matter in the Universe holds many keys to understanding some of the greatest cosmic mysteries.
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In fact, I'd say that one of the most common popular misunderstandings involves the difference between the entropic dynamics at stellar scales, as apposed to the dynamics we live with at pedestrian scales. Language is often the culprit.
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"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.
From coffee to hot chocolate to soup, hot beverages are a staple of winter. But no one wants it scalding! Blowing on your hot drink cools it down, but not the way you think.
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Unrelated perhaps, but when I have a very hot meal, I don't wait for it to cool down. I just spread it over the entire plate, or cut it up so that almost every part is exposed to open air. I'm sure many other people do the same thing.
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Work
Occupation
Theoretical Astrophysicist / Writer / Educator
Employment
  • NASA's The Space Place
    Columnist, 2013 - present
  • Trap!t
    Head Editor: Science/Health, 2011 - present
  • Starts With A Bang!
    Science Writer, 2008 - present
  • Lewis & Clark College
    Visiting Assistant Professor of Physics, 2009 - 2011
  • University of Portland
    Professor/Lab Coordinator, 2008 - 2009
  • Steward Observatory/University of Arizona
    Postdoctoral Research Associate, 2007 - 2008
  • University of Wisconsin
    Faculty Assistant, 2006 - 2007
  • University of Florida
    Teaching/Research Assistant, Fellow, 2001 - 2006
  • King/Drew Medical Magnet High School
    Teacher, 2000 - 2001
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Bronx, New York - Yonkers, New York - Evanston, Illinois - Torrance, California - Gainesville, Florida - Madison, Wisconsin - Tucson, Arizona - Portland, Oregon - Houston, Texas - Rome, Italy
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Science writer, professor and theoretical astrophysicist
Introduction
Theoretical Astrophysicist, Science Writer and Communicator, expert in (some aspects of) dark matter and dark energy, physical cosmology, and sometimes professor, teacher and educator.

Creator and writer of Starts With A Bang!, the 2010 Physics Blog of the Year! Author of over 1,000 articles, featured in Esquire, the St. Petersburg Times, ESPN.com's Page 2, and many others.

Competitive beardsman and amateur acrobat / halloween-costumer extraordinaire.
Education
  • University of Florida College of Liberal Arts and Sciences
    Physics, 2001 - 2006
  • Northwestern University
    Physics, Classics, Integrated Science Program, 1996 - 2000
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