These guys look like they are getting their bong ready, but in truth, they are up to something else. Everybody knows that neutrinos are everywhere, yet, nearly impossible to detect. A group of scientists have managed to pull off over 100 detection events over the course of about a year and a half using an entirely new method. From the abstract of their paper:
The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross-section is the largest by far of all low-energy neutrino couplings. This mode of interaction provides new opportunities to study neutrino properties, and leads to a miniaturization of detector size, with potential technological applications. We observe this process at a 6.7-sigma confidence level, using a low-background, 14.6-kg CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the Standard Model for this process, are observed in high signal-to-background conditions. Improved constraints on non-standard neutrino interactions with quarks are derived from this initial dataset.
A summary of the story, which I think is not behind a paywall, is here. The science article is here.
Burratti is a planetary astronomer at NASA’s JPL, and is the head of the Comets, Asteroids and Satellites Group. She was a key player in the Voyager program, and in the research done with the Cassini-Huygens, and New Horizons space ships.
Worlds Fantastic, Worlds Familiar: A Guided Tour of the Solar System is a personal exploration of what it is like to personally (via robots) explore our solar system, and at the same time, a systematic accounting of the solar system. The story is told, I think, as a geologist might tell it, about land forms and surface features. In other words, it is a somewhat finer scale look at the very big scale picture of the solar system, which is something that could not possibly have been done prior to the exploration of that solar system with these various flying robots. Which, Bonnie Buratti herself flew, directed, or otherwise played around with.
What is the nature of space and time? How do we fit within the universe? How does the universe fit within us? There’s no better guide through these mind-expanding questions than acclaimed astrophysicist and best-selling author Neil deGrasse Tyson.
But today, few of us have time to contemplate the cosmos. So Tyson brings the universe down to Earth succinctly and clearly, with sparkling wit, in tasty chapters consumable anytime and anywhere in your busy day.
While you wait for your morning coffee to brew, for the bus, the train, or a plane to arrive, Astrophysics for People in a Hurry will reveal just what you need to be fluent and ready for the next cosmic headlines: from the Big Bang to black holes, from quarks to quantum mechanics, and from the search for planets to the search for life in the universe.
Give a listen to my interview with NdGT, from a few years back. Which, by the way, was a great interview, because I did two things to prepare. First, I checked out several other interviews done of him, and vowed to not ask any of those questions. Second, I read all his books and looked into his professional and academic background, and mostly asked him questions about his area of research. Do you know what his specific research area is? Most people don’t. Find out.
His new book is actually more about his research are than many of his other books are.
As more and more exoplanets (at first) and earth-like exoplanets (eventually) have been discovered, the way thy are described to us has become increasingly sophisticated. Below are embeds of diverse video descriptions that have been very quickly developed and distributed given the freshness of this latest scientific discovery. Note that the practice of very clearly stating that a particular depiction of something that no human has ever seen, or will ever see, as being an artist’s reconstruction has largely fallen by the wayside. Exoplanets are no longer physical features of the universe occassionally glimpsed by astronomers with very fancy Big Science Gear. They are now stories, where almost all the details and even implications are made up.
From the Telegraph:
From the Guardian:
From NASA via CNN:
Additional small exoplanet discovered in alleyway:
This is a concept that has always fascinated me, ever since reading some stuff about the Periodic Table of Elements. Check it out:
Over the last forty years, scientists have uncovered evidence that if the Universe had been forged with even slightly different properties, life as we know it – and life as we can imagine it – would be impossible. Join us on a journey through how we understand the Universe, from its most basic particles and forces, to planets, stars and galaxies, and back through cosmic history to the birth of the cosmos. Conflicting notions about our place in the Universe are defined, defended and critiqued from scientific, philosophical and religious viewpoints. The authors’ engaging and witty style addresses what fine-tuning might mean for the future of physics and the search for the ultimate laws of nature. Tackling difficult questions and providing thought-provoking answers, this volumes challenges us to consider our place in the cosmos, regardless of our initial convictions.
Understanding risk, and misunderstanding it, became a major topic of discussion, initially in economics, about the time that I was working in a major think tank where much of this discussion was happening. Risk perception had been there as a topic for a while (the head risk-thinker where I worked had already won a Nobel on the topic) but it became a popular topic when a couple of economists figured out how to get the message out to the general public.
In my view, the modern analsyis of risk perception is deeply flawed in certain ways, but very valuable in other ways. This book is very relevant, and very current, and is the go to place to assess health related risk issues, and I think it is very good. I do not agree with everything in it, but smart people reading a smart book … that’s OK, right?
Do cell phones cause brain cancer? Does BPA threaten our health? How safe are certain dietary supplements, especially those containing exotic herbs or small amounts of toxic substances? Is the HPV vaccine safe? We depend on science and medicine as never before, yet there is widespread misinformation and confusion, amplified by the media, regarding what influences our health. In Getting Risk Right, Geoffrey C. Kabat shows how science works?and sometimes doesn’t?and what separates these two very different outcomes.
Kabat seeks to help us distinguish between claims that are supported by solid science and those that are the result of poorly designed or misinterpreted studies. By exploring different examples, he explains why certain risks are worth worrying about, while others are not. He emphasizes the variable quality of research in contested areas of health risks, as well as the professional, political, and methodological factors that can distort the research process. Drawing on recent systematic critiques of biomedical research and on insights from behavioral psychology, Getting Risk Right examines factors both internal and external to the science that can influence what results get attention and how questionable results can be used to support a particular narrative concerning an alleged public health threat. In this book, Kabat provides a much-needed antidote to what has been called “an epidemic of false claims.”
In the not too distant past, it was understood that we, the humans, were going to run out of food within a certain defined time range. This actually happened several times, this estaimte, followed by the drop-dead date coming and going, and the species continued. Kind of embarassing.
Historically, that estimate of when we would run out of food has been wrong for one, two, or all of three reasons. First, the rate of population increase can be misestimated. We now know a lot more about how that works, and still probably can’t get it right, but in the past, this has been difficult to guess. Second, it hasn’t always been about food production, but rather, distribution or other aspects of the food supply. Right now, the two big factors that need to be addressed in the future are probably commitment to meat and waste. Third, and this is the one factor that people usually think of first, is how much food is produced given the current agricultural technology. That third factor has changed, in the past, several times, usually increasing but sometimes decreasing, depending on the region or crop. Sadly, this is probably also the factor that will change least (in a positive direction) in the future, even given the supposed promise of GMOs, which have so far had almost no effect.
Anyway, this book is about this topic:
The astounding success of agricultural research has enabled farmers to produce increasingly more—and more kinds—of food throughout the world. But with a projected 9 billion people to feed by 2050, veteran researcher Gale Buchanan fears that human confidence in this ample supply, especially in the US, has created unrealistic expectations for the future. Without a working knowledge of what types and amounts of research produced the bounty we enjoy today, we will not be prepared to support the research necessary to face the challenges ahead, including population growth, climate change, and water and energy scarcity.
In this book, Buchanan describes the historical commitment to research and the phenomenal changes it brought to our ability to feed ourselves. He also prescribes a path for the future, pointing the way toward an adequately funded, more creative agricultural research system that involves scientists, administrators, educators, farmers, politicians, and consumers; resides in one “stand alone” agency; enjoys a consistent funding stream; and operates internationally.
Gene editing and manipulation has come a long way. We may actually be coming to the point where methods have started to catch up with desire, and applications may start taking up more of the news cycle. We’ll see. Anyway:
Would you change your genes if you could? As we confront the ‘industrial revolution of the genome’, the recent discoveries of Crispr-Cas9 technologies are offering, for the first time, cheap and effective methods for editing the human genome. This opens up startling new opportunities as well as significant ethical uncertainty. Tracing events across a fifty-year period, from the first gene splicing techniques to the present day, this is the story of gene editing – the science, the impact and the potential. Kozubek weaves together the fascinating stories of many of the scientists involved in the development of gene editing technology. Along the way, he demystifies how the technology really works and provides vivid and thought-provoking reflections on the continuing ethical debate. Ultimately, Kozubek places the debate in its historical and scientific context to consider both what drives scientific discovery and the implications of the ‘commodification’ of life.
Did you ever notice that Pluto doesn’t have much of a tail? No, not that Pluto! This Pluto:
This has been known for a while. NASA noted this last year:
New Horizons has discovered a region of cold, dense ionized gas tens of thousands of miles beyond Pluto — the planet’s atmosphere being stripped away by the solar wind and lost to space. Beginning an hour and half after closest approach, the Solar Wind Around Pluto (SWAP) instrument observed a cavity in the solar wind — the outflow of electrically charged particles from the Sun — between 48,000 miles (77,000 km) and 68,000 miles (109,000 km) downstream of Pluto. SWAP data revealed this cavity to be populated with nitrogen ions forming a “plasma tail” of undetermined structure and length extending behind the planet.
Not long ago it was not known that Pluto had an atmosphere. But it does, and it is probably made from solid ice that makes up a good portion of the planet. When Pluto is nearer the Sun, this atmosphere burns off and forms an unimpressive tail. (Existentially impressive, but not fireworks impressive.) If Pluto were to come really close to the sun, like a typical comet, it would … well, it would essentially be a a comet. A pretty big one, at first. But then after several passes…
Anyway, more recently, it has been discovered that Pluto also puts out X-rays, and if confirmed, this is interesting. The total number of X-rays that have been detected is very small. The existence of these X-rays is likely linked to the atmosphere. From NASA:
Scientists using NASA’s Chandra X-ray Observatory have made the first detections of X-rays from Pluto. These observations offer new insight into the space environment surrounding the largest and best-known object in the solar system’s outermost regions.
While NASA’s New Horizons spacecraft was speeding toward and beyond Pluto, Chandra was aimed several times on the dwarf planet and its moons, gathering data on Pluto that the missions could compare after the flyby. Each time Chandra pointed at Pluto – four times in all, from February 2014 through August 2015 – it detected low-energy X-rays from the small planet.
Pluto is the largest object in the Kuiper Belt, a ring or belt containing a vast population of small bodies orbiting the Sun beyond Neptune. The Kuiper belt extends from the orbit of Neptune, at 30 times the distance of Earth from the Sun, to about 50 times the Earth-Sun distance. Pluto’s orbit ranges over the same span as the overall Kupier Belt.
“We’ve just detected, for the first time, X-rays coming from an object in our Kuiper Belt, and learned that Pluto is interacting with the solar wind in an unexpected and energetic fashion,” said Carey Lisse, an astrophysicist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, who led the Chandra observation team with APL colleague and New Horizons Co-Investigator Ralph McNutt. “We can expect other large Kuiper Belt objects to be doing the same.”
The team recently published its findings online in the journal Icarus. The report details what Lisse says was a somewhat surprising detection given that Pluto – being cold, rocky and without a magnetic field – has no natural mechanism for emitting X-rays. But Lisse, having also led the team that made the first X-ray detections from a comet two decades ago, knew the interaction between the gases surrounding such planetary bodies and the solar wind – the constant streams of charged particles from the sun that speed throughout the solar system – can create X-rays.
New Horizons scientists were particularly interested in learning more about the interaction between the gases in Pluto’s atmosphere and the solar wind. The spacecraft itself carries an instrument designed to measure that activity up-close – the aptly named Solar Wind Around Pluto (SWAP) – and scientists are using that data to craft a picture of Pluto that contains a very mild, close-in bowshock, where the solar wind first “meets” Pluto (similar to a shock wave that forms ahead of a supersonic aircraft) and a small wake or tail behind the planet.
The immediate mystery is that Chandra’s readings on the brightness of the X-rays are much higher than expected from the solar wind interacting with Pluto’s atmosphere.
“Before our observations, scientists thought it was highly unlikely that we’d detect X-rays from Pluto, causing a strong debate as to whether Chandra should observe it at all,” said co-author Scott Wolk, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “Prior to Pluto, the most distant solar system body with detected X-ray emission was Saturn’s rings and disk.”
The Chandra detection is especially surprising since New Horizons discovered Pluto’s atmosphere was much more stable than the rapidly escaping, “comet-like” atmosphere that many scientists expected before the spacecraft flew past in July 2015. In fact, New Horizons found that Pluto’s interaction with the solar wind is much more like the interaction of the solar wind with Mars, than with a comet. However, although Pluto is releasing enough gas from its atmosphere to make the observed X-rays, in simple models for the intensity of the solar wind at the distance of Pluto, there isn’t enough solar wind flowing directly at Pluto to make them.
Lisse and his colleagues – who also include SWAP co-investigators David McComas from Princeton University and Heather Elliott from Southwest Research Institute – suggest several possibilities for the enhanced X-ray emission from Pluto. These include a much wider and longer tail of gases trailing Pluto than New Horizons detected using its SWAP instrument. Other possibilities are that interplanetary magnetic fields are focusing more particles than expected from the solar wind into the region around Pluto, or the low density of the solar wind in the outer solar system at the distance of Pluto could allow for the formation of a doughnut, or torus, of neutral gas centered around Pluto’s orbit.
That the Chandra measurements don’t quite match up with New Horizons up-close observations is the benefit – and beauty – of an opportunity like the New Horizons flyby. “When you have a chance at a once in a lifetime flyby like New Horizons at Pluto, you want to point every piece of glass – every telescope on and around Earth – at the target,” McNutt says. “The measurements come together and give you a much more complete picture you couldn’t get at any other time, from anywhere else.”
New Horizons has an opportunity to test these findings and shed even more light on this distant region – billions of miles from Earth – as part of its recently approved extended mission to survey the Kuiper Belt and encounter another smaller Kuiper Belt object, 2014 MU69, on Jan. 1, 2019. It is unlikely to be feasible to detect X-rays from MU69, but Chandra might detect X-rays from other larger and closer objects that New Horizons will observe as it flies through the Kuiper Belt towards MU69.
The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft and manages the mission for NASA’s Science Mission Directorate. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.
In linguistic communication, a pattern generally emerges whereby the speaker or the listener (but not both) work extra hard to make the communication happens. This work (or lack thereof) consists of enunciation, use of contractions, various other things. You know about this because you make such adjustments all the time. When speaking to a child, or when speaking about your area of expertise but to a non-expert, etc., you not only use an adjusted vocabulary but also speak more clearly and maybe even more loudly; you end up doing more of the work than you would usually do.
Entire cultural entities, back in the old days when lingusists were still anthropologists, could be classified (probably too arbitrarily) in this way, where in one setting speakers did little of the work and the listeners had to work harder, but in other settings, the opposite was true.
When we humans speak on radios, I get the impression that everyone is working extra hard because of the interference. Also, if there is a dispatcher or central voice of some kind, I think the dispatcher or equivalent works harder and those out on the periphery don’t work very hard at all. To see for yourself, listen to a police band radio for a while.
Dispatcher: “Unit 41, code 11 at Main and Fourth.”
Unit 41: “KSshhhhs blorp bleep. Ain orth.”
That sort of thing.
Some of this has to do with the quality of the radio signal coming from some places. So, when human astronauts are out visiting other planets, you can get this effect as well.
Houston: Thirteen, we’ve got one more item for you, when you get a chance. We’d like you to stir up your cyro tanks. In addition, I have a shaft and trunnion –
Apollo 13: Ksshsh Kay
Houston: ..for looking at the Comet Bennett, if you need it.
Apollo 13: Bleep blorp k standby
Apollo 13: Kssh k ooson i elieve we’ve had a problem herksshh.
Houston: This is Houston. Say again, please.
Apollo 13: Oh ksssh Houston we’ve had a problem blorp. Ba bee bee a boblrt undervolt.
Houston: Roger. Main B undervolt. OK stand by 13, we’re looking at it.
(Oddly, from this point on in that historic transmission between Earth and Outer Space, the words from the Apollo 13 astonauts start to become clearer than the words from Houston. As though Houston had it’s hands over the mouthpiece for a while.)
Which brings us to Neil Armstrong’s moonlanding quote. What did he say exactly?
Well, being a human, I am quite certain that I know what he said and what he meant. This is what he said:
“That’s one small step for man, one diant leap for mankind.”
But this is probably a better transcription of what he said:
“That’s one small step for a man, one giant leap for mankind.”
What he meant by that:
“So one guy can hop off the foot pad of a Lunar Landing module, no biggie, but in this case, this is a huge leap forward in the history of our species since we are now walking around on another planet. Albeit one circling our own, not like we just landed on Jupiter or something.”
So it is likely that what we actually heard was:
“One small step for BLORP man, one DORPiant leap for mankind”
Where I have substituted nonsense for the missing or messed parts.
To deal with this apparent ambiguity, NASA has generally written the quote as following, provisionally adding the indefinite article and converting “diant” to “giant.”
“That’s one small step for (a) man, one giant leap for mankind.”
And now, a team of linguists writing in PLoS ONE report that even though we couldn’t hear it, Armstrong probably did say “a” before “man.” From the abstract of the paper:
Neil Armstrong insisted that his quote upon landing on the moon was misheard, and that he had said one small step for a man, instead of one small step for man. What he said is unclear in part because function words like a can be reduced and spectrally indistinguishable from the preceding context. Therefore, their presence can be ambiguous, and they may disappear perceptually depending on the rate of surrounding speech. Two experiments are presented examining production and perception of reduced tokens of for and for a in spontaneous speech. Experiment 1 investigates the distributions of several acoustic features of for and for a. The results suggest that the distributions of for and for a overlap substantially, both in terms of temporal and spectral characteristics. Experiment 2 examines perception of these same tokens when the context speaking rate differs. The perceptibility of the function word a varies as a function of this context speaking rate. These results demonstrate that substantial ambiguity exists in the original quote from Armstrong, and that this ambiguity may be understood through context speaking rate.
Now, there is yet another interpretation. Here’s audio of the actual event.
Here is my interpretation of what actually happened. The words Armstrong said are in bold. The words that were only in his head are in italics.
And I’ll step off the LEM now.
Holy fuck. The moon.
That’s one small step for BLORP man.
Crap, did I just leave out the “a.” Not sure. Should I say it again? No, that would be worse. Maybe I just said it real fast. Whatever. Everybody will get what I mean. This will not be a controversy.
One giant leap for mankind.
Holy fuck. The moon.
So, that controversy, if it ever was a controversy, has been dealt a mighty blow.
Sometimes I think there are not abundant intelligent life forms wafting about the universe. We would see things in our careful, highly accurate, detailed looking at a sampling of the universe. But, I suppose we’ve only been scanning with super amazing instruments for a few years, and only scanning a small fraction of the universe. But certainly, in a decade or two we’ll be able to say that radio-communicative or emitting intelligent life is either out there somewhere, or not likely to be. Absence of evidence will evolve into evidence for pessimism, at the very least.
Meanwhile we get these little quirks. And, the latest is a burst of radio-info that the experts on this all seem to be saying is not a thing, looks like lots of other things that are also not things, but one guy somewhere put out a press release so now everybody thinks it is a thing.
The star that is nearest our own has a planet that could be habitable by Earthlings.
This is very important news.
The news comes to us from this research paper in Nature: A terrestrial planet candidate in a temperate orbit around Proxima Centauri by Guillem Anglada-Escudé, Pedro J. Amado, John Barnes, Zaira M. Berdiñas, R. Paul Butler, Gavin A. L. Coleman, Ignacio de la Cueva, Stefan Dreizler, Michael Endl, Benjamin Giesers, Sandra V. Jeffers, James S. Jenkins, Hugh R. A. Jones, Marcin Kiraga, Martin Kürster, Mar?a J. López-González, Christopher J. Marvin, Nicolás Morales, Julien Morin, Richard P. Nelson, José L. Ortiz, Aviv Ofir, Sijme-Jan Paardekooper, Ansgar Reiners, Eloy Rodríguez, Cristina Rodr?guez-López, Luis F. Sarmiento, John P. Strachan, Yiannis Tsapras, Mikko Tuomi & Mathias Zechmeister.
At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (? Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun’s closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface.
Here’s why this is important. We knew that some stars that are like ours had Earth-like planets. How did we know that? Because we live on one. But how many Sun-like stars have Earth-like planets?
Trivially, we knew that all the known Sun-like stars had Earth-like planets. But that was with a sample size of one. We needed a larger sample size to estimate the actual percentage of Sun-like stars that had Earth-like planets.
Given that, consider the following question. We have a second Sun-like star. If it has no Earth-like planets, what do you think of the overall proportion of stars that have such planets? Perhaps you would guess 50-50, but the sample size is too small. Safer to simply guess, “maybe not many, because the first time we got to increment our sample size, we got nada.” Now, if it does have an Earth-like planet, what do you think of the overall proportion of stars that have such planets? Perhaps you would guess 100%, but again, the sample size is too small. But, you would safely say something like, “Well, hell, maybe a lot of them, because of the two where we have enough information to say … both have them!”
There really is no reasonable statistical way to treat this problem, but this sort of seat of the pants conjecture isn’t bad for now. But, if we were to have, say, five or six Sun-like stars to look at, we could start making real guesses.
There is a second reason. Now that we have an Earth like planet in our sights, perhaps there will be impetus for both funding and effort to squint really really hard at it and see if any life is there. Using fancy science, not actual squinting, of course.
Let us be clear. This planet is not Earth-like in that it has an atmosphere, water, or any sign of life. The planet might be locked in its orbit around its star in such a way that one side always faces that star. That would be bad for an atmosphere and for life. We don’t know if it has an atmosphere, or water. What we do know is that if water is on the surface, it might be liquid, and if an atmosphere ever formed there, maybe (though this is highly debatable) it did not necessarily get blown away into space or otherwise destroyed.
We talk about the history of understanding the universe, why you should believe in Dark Matter even though it is obviously fake, why exploring uranus can lead to the discovery of amazing things, and more.
There is little that is cooler than robots on mars doing science. Human space agencies have been sending probes to the surface of various planets (and the Moon) for years now, with the full range of failure and success. But the last decade or so has seen space robots such as Mars Curiosity Rover sciencing the shit, as they say, out of the planet Mars.
Emily Lakdawala, of the Planetary Society, is a planetary geologist and science communicator who knows a lot about driving rovers. It turns out that this is all very complicated, and when science gets big, expensive, high stakes, and complicated, it isn’t uncommon to find a diminishing number of individuals with a sufficient handle on all its aspects that they can explain most things to most people most of the time.
Emily’s framework for science communication is not that different from my own. I’m a scientist who likes to talk to non scientists at a level or two above the press release, and that’s what Emily does on her blog.
So, for all these reasons, Mike Haubrich and I were very happy to have the opportunity to interview Emily on Ikonokast.
I find it interesting that some people are expressing difficulty in understanding what a gravitational wave is, as though everybody (who is not a physicist) has a perfectly good understanding of what any kind of wave is. We don’t need to go too deeply beneath the surface, as it were, to understand this well enough to be amazed at the discovery, but not well enough to get a job being a Gravitational Waveologist.
Imagine a perfectly flat pond. Imagine throwing a stone out into the middle of the pond. Now imagine ripples, tiny waves, spreading out from the point where the rock hit the pond.
Now imagine the smallest possible stone that could produce a visible wave on the water. It would be pretty small. The ripples would be pretty small.
Gravitational waves are just like that, but even smaller, so you can’t see them. Not that you would “see” them with your eyes, but rather, you can’t detect them, in any normal way.
They won’t make the moon wobble, or a bird fall out of the sky. You know about super sensitive satellites that orbit the earth detecting variations in gravity such as the decrease in the pull of a glacier on the nearby ocean when the glacier melts by way less than one percent, and that sort of thing. Gravitational waves are presumably passing through that satellite all the time, but it can’t detect them.
Since they had not been detected for a long time, it had not been 100% certain that they exist. However, evidence for their existence has been mounting, and they have, in a sense, been indirectly observed.
Gravitational waves were first postulated by Einstein as early as 100 years ago as part of his application of his General Theory of Relativity, though he later temporarily retracted the idea (but then put it back).
Russian scientists advanced ways of detecting them in the 1960s, and one scientist thought he had found them a bit later in time. Further methods were developed to try to see them. In 1974 one group detected the slowing down of a pulsar orbiting a neutron star in such a way that implicated “gravitational radiation,” and this work stood (and earned a Nobel Prize). That was probably the first actual “detection” of the waves, in a sense.
In the late 1970s, the LIGO project was started to build a gravitational wave detecting antenna. In 1996, the VIRGO project was started in Italy. The Germans had just built GTO600, and partnered with LIGO soon after.
Over the last five years, the LIGO wave detector was upgraded, and after a period of time being turned off, was started up again in September. And bingo, there was a gravitational wave. Detected. Probably.
Long ago, deep in space, two massive black holes—the ultrastrong gravitational fields left behind by gigantic stars that collapsed to infinitesimal points—slowly drew together. The stellar ghosts spiraled ever closer, until, about 1.3 billion years ago, they whirled about each other at half the speed of light and finally merged. The collision sent a shudder through the universe: ripples in the fabric of space and time called gravitational waves. Five months ago, they washed past Earth. And, for the first time, physicists detected the waves, fulfilling a 4-decade quest and opening new eyes on the heavens.
The discovery marks a triumph for the 1000 physicists with the Laser Interferometer Gravitational-Wave Observatory (LIGO), a pair of gigantic instruments in Hanford, Washington, and Livingston, Louisiana. Rumors of the detection had circulated for months. Today, at a press conference in Washington, D.C., the LIGO team made it official. “We did it!” says David Reitze, a physicist and LIGO executive director at the California Institute of Technology (Caltech) in Pasadena. “All the rumors swirling around out there got most of it right.”
The way you detect a gravitational wave is to place two objects some distance from a laser source. You hit both objects with the laser and measure the return time, which should be exactlyvthe same for each object. If either object moves, that might have been because of a gravitational wave.
Obviously objects are going to move. Temperature changes, vibrations in the earth, all those things, can cause the objects to vibrate or move in some way. So you figure all that out and make all those things impossible. Also, the objects have to be really far out in order to get a signal. In the case of LIGO, the objects are four kilometers out from the laser source.
Yes, there is a reason that LITO was first funded in 1979 and only now has a result!
Now, here’s the part I don’t like. I don’t like the fact that the device was turned off and upgraded, then, very soon after being turned on, found a gravitational wave, and apparently hasn’t found another since then. I’m worried that this is similar to when CERN detected faster than light neutrinos. Everybody knew there were no faster than light neutrinos, but the instruments detected them anyway. Eventually, it was discovered that something was going on with the way the instruments were wired up that made the detector wrong.
“I think it’s very convincing. The reason they’ve waited months from the actual detection to report the event was so that they could check every possible source of artifact that might be something other than a real signal. So at this point, it’s well over 99% likely that the detection is real. Remember that the detection was made by both LIGO sites — Louisiana and Washington — and the delay between the two signals agrees with the light travel time. As to the “coincidence” — it depends on how rare or common these events are. Currently, no one has a good prediction for how often 2 black holes should collide and merge somewhere in the universe. If such events are very rare — e.g., one every 10 years or one every century — then it would indeed be a surprising coincidence. But if these events happen, say, once a year or more, then we’d expect to get a signal within a few months of starting a machine like this. The real test, then, will be whether other similar signals are detected over the next few years. I suspect they will be, and so it will turn out that these events are relatively common…”
Is there something wrong with the LIGO detector?
See the link to Science Magazine above for discussion of how hard the team worked to eliminate alternative explanations. Quite a bit, and quite convincing. But the gravity of this situation, this new discover, is so great that it may be good to retain a small amount of healthy skepticism.
By the way, don’t confuse “gravitational waves” with “gravity waves.” Going back to the pond, the ripples or waves on the water. Those are technically called gravity waves, as are some of the patterns we see in clouds. This is simply wave energy within a gravitational field. Gravitational waves are a totally different thing.
This month is the twentieth anniversary of the discovery of exoplanets, which are really just planets that are not in our solar system. (Frankly, I dislike the term exoplanet. It is so solarcentric.)
When you think about it, the discovery of planets outside our solar system (we need a word for that) is a special thing. On a graph of how expected and mundane a scientific discovery is vs. how exciting a scientific discovery is, these planets are distant outliers.
For years astronomers and cosmologists and others assumed that stars would generally have planets around them, or at least, this would often be the case. This is all part of the famous Drake Equation, best stated by Carl Sagan using the word “Billions” (with two b’s) over and over again. Like this.
OK, he didn’t really use “Billions” a bunch of times. But he might have.
Anyway, Nature.com has a nice set of infographics on the topic, one of which I’ve posted above. The rest are here.
Skylab came up in conversation the other day. And then I ran into Amy Shira Teitel’s video. So, naturally, a quick blog post.
Skylab was brought down, ultimately, by interaction with the upper reaches of the atmosphere, which was in turn made more likely by solar activity. But, both the nature and extent of solar activity of this type, and its effects on the atmosphere, were not understood when Skylab was being designed and deployed. Indeed, understanding this set of phenomena was a contribution made by Skylab science. Had Skylab been launched after, rather than before, this was better understood, it may have been put into higher orbit, or it may have been equipped with boosters (like the International Space Station is) to periodically raise the orbit.
Anyway, eventually, the orbiting research lab came down, and you may (or may not) remember all the press, the jokes, the anxiety, the fun…
Anyway, Amy has this piece on what NASA did and didn’t do about Skylab’s demise.
Short answer: Pluto has only two of the three necessary characteristics to be called a planet. Pluto has not cleared its neighborhood, or orbit. But, of course, there are additional details.
The simplest reason that Pluto is not a planet is that planet experts say so, and this is their job. But you may be looking for a more detailed explanation.
Let’s look at what defines a planet. This could be a very long and tedious discussion, because “planet” is an ancient concept used long before scientists knew very much about them. Also, frankly, in many areas of science the definition of a thing, perhaps counter-intuitively to non-scientists, is often pretty irrelevant to its study. Definitions that change over time that are never quite in line with the phenomenon being observed, etc. may seem like an impediment to science, but they often are not. The definition of a “gene” has changed dramatically as we’ve learned more about them, but this shifting description has not hampered genetic research. To some extent this may be the same with planets. A “planetologist” who studied Pluto back when it was still counted as a planet would not have to find a new job when our solar system went from 9 to 8.
The International Astronomical Union has settled on a set of definitions of solar system bodies, which includes planets, dwarf planets (which are mostly minor planets), small solar system bodies, trans-Neptunian objects which also might be called plutoids (those are also minor planets) and some small solar system bodies (including some comets) and satellites, and satellites are, of course, things that go around things that are not the Sun. Confused? Probably, but that is not a big problem because while these various identified flying objects have complex overlapping categorical status, one type of object does not. Planets are planets and they are not anything other than planets.
To be a planet, you have to be in orbit around the Sun. This would rule out the Moon, which, if it was in orbit around the Sun instead of the Earth, could well be a planet.
To be a planet the object has to have sufficient mass to have been shaped by gravity to be (mostly) a globe. This depends on various things so at the low end of the mass spectrum there will be different masses and different sizes of things that don’t quite make it to globular status.
To be a planet the object has to have cleared its orbit. In other words, as an object orbits around the sun, it is likely to bump into other objects. Over a period of time, the object has finished bumping into everything it is likely to bump into, and thereafter has only a low probability of bumping into something. That does not rule out something bumping into the object, of course.
A globe shaped object that goes around the sun but that has not cleared its orbit is classified as a “dwarf planet.” This is of course historically contingent. In the early days of a solar system, perhaps there would be large star-circleing round things that have not yet cleared their orbit. This speaks to the strangeness of definitions alluded to above. The definition we use today to classify our solar system’s objects applies to a solar system developed to the extent ours is developed. The IAU nomenclature would probably need revisions if applied to all planetary-star systems in the Universe.
This scheme is not without its critics and there is indeed debate. Some of that debate is a bit nitpicky but still interesting. For example, Alan Stern, with NASA, notes that many planets have not really cleared their orbit, noting in relation to the Pluto controversy, “If Neptune had cleared its zone, Pluto wouldn’t be there.” Yes, apparently heavenly bodies have irony.
Anyway, as implied, Pluto is not classed as a planet because it has not cleared its orbit. Therefore it is a Dwarf Planet. Since it is far away (farther than Neptune) it also gets classed as a Trans-Neptunian Object. Furthermore, it is a Plutoid. That is simply a newer term applied to Trans-Neptuina dwarf planets.
The term Plutoid, then, refers to a dwarf planet, which for various reasons is apparently always specifically an ice dwarf, which is a trans-Neptunian body (orbiting most of the time beyond Neptune) that is sufficiently massive to be shaped like a globe. This term, plutoid, is officially adopted A plutoid or ice dwarf is a trans-Neptunian dwarf planet, i.e. a body orbiting beyond Neptune that is large enough to be rounded in shape. The term plutoid was adopted by the International Astronomical Union’s Committee on Small Bodies Nomenclature, but not by the working group on Planetary System Nomenclature. So you can use Plutoid or Dwarf Planet, or Ice Dwarf, depending on whom you wish to annoy.
Pluto, Eris, Haumea, and Makemake are the only known Plutoids. They are small enough and far enough away that more could be discovered.