Education

Exploring Space: Don't Sell Robots Short [Uncertain Principles]

Science Blogs Physcial Sciences - 9 May, 2012 - 17:02

One final thought on the Big Science/ Space Chronicles stuff from last week. One of the things I found really frustrating about the book, and the whole argument that we ought to be sinking lots of money into manned space missions is that the terms of the argument are so nebulous. This is most obvious when Tyson or other space advocates talk about the need for "inspiring" people, but it shows up even in what ought to be relatively concrete discussions of actual science.

Take, for example, the argument over humans vs. robots. Given the success of the robotic missions to Mars and other bodies, many people ask why we should bother to send people to any of those places. Tyson himself estimates the cost of sending a human to be around fifty times the cost of sending a robot, and says that "if my only goal in space is to do science, and I'm thinking strictly in terms of the scientific return on my dollr, I can think of no justification for sending a person into space." But then, he turns around and tries to justify it on fairly standard grounds: that humans are more flexible, while a robot can only "look for what it has already been programmed to find." Having humans on the scene would enable faster and more "revolutionary" discoveries.

This is an argument that sounds fairly convincing on a surface level, but on closer inspection it breaks down in two ways: it's too generous to humans, and too hard on the robots.

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Categories: Education

Nano-Alchemy: Turning Nickel into Platinum [Brookhaven Bits & Bytes]

Science Blogs Physcial Sciences - 9 May, 2012 - 15:02

This post was written by Brookhaven Lab science writer Justin Eure.

With nanotechnology rapidly advancing, the sci-fi dream of a Star Trek replicator becomes increasingly less fantastic. But such radical technology would, in theory, require the kind of subatomic manipulation that far exceeds current capabilities. Scientists lack both the equipment and the fundamental knowledge of quantum mechanics (the Standard Model, for all its elegance, remains incomplete) to build items from the raw stuff of quarks, gluons, and electrons . . . but what about alchemy?

Midas TouchEven Isaac Newton, credited with the dawn of the Age of Reason, felt the mystical draw of alchemy, working in secret to transform one element into another. Centuries later we still can't conjure gold from lead, sure, but what if it was possible to combine a handful of elements to very closely mimic gold? What if scientists engineered a synthetic Midas Touch that tricked base metals into performing like gold, thereby conquering the hurdles of rarity and price?

Now forget the alchemist's dream of gold and consider the equally precious noble metal platinum - hovering right around $50,000 per kilogram - which may be the key to building a sustainable energy future. Now, using advanced technology and elements that cost 1000 times less, researchers at Brookhaven National Lab have created a high-performing pauper's platinum from nanoscale building blocks.

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Categories: Education

Exoplanet Bullies make Earth-like Planets Impossible [Starts With A Bang]

Science Blogs Physcial Sciences - 9 May, 2012 - 02:20

"There's nothing that cleanses your soul like getting the hell kicked out of you."
-Woody Hayes There's no doubt that we lucked out when it came to the formation of our Solar System.

figure_1.jpeg

(Image credit: Michael Pidwirny, retrieved from here.)

Our inner Solar System, where temperatures are ideal for liquid water and life-as-we-know-it, is full of rocky planets and devoid of any gas giants for many hundreds of millions of miles. But, as we know all too well from the last twenty years of finding exoplanets, this isn't the only way it could have turned out.

In fact, of the some 2,300 planets found around other stars so far, the vast majority of them are either very, very hot, very, very large, or both.

Thorp_and_Underkoffler.jpg

(Image credit: Jer Thorp and John Underkoffler.)

This could just be due to the fact that those types of planets are the easiest ones to find with the technology and techniques we have available to us right now, and we may wind up finding more solar systems like ours. What seems most important, at least as far as the search for extraterrestrial life (or possibly habitable exoplanets) goes, is looking for rocky planets where the temperature is right for liquid water.

And every star has a region around it where that's possible.

CompLifeZoneRGBwTxt_512px.jpeg

(Image credit: Kepler Mission / NASA, retrieved from here.)

But although we've found a small but important number of stars with rocky planets that live in their habitable zones, there's one type of exoplanet system that never has a rocky planet in their habitable zones.

Not only that, but they -- at least so far -- never have any other planets in their solar systems! What gives?

Hot-Jupiters-May-Prevent-Earth-Like-Worlds-From-Forming-2.jpeg

(Image credit: NASA / GSFC, retrieved from Softpedia.)

Over in our Solar System, we've got our rocky worlds interior to all of our gas giants, with an asteroid belt interior to the giant planets, and a kuiper belt exterior to our four Jovians. But in systems where there's a Hot Jupiter, or a gas giant very close to its parent star, we don't find any other planets anywhere near the star itself.

Why is that?

Study-Hot-Jupiters-found-to-be-loners.jpeg

(Image credit: European Southern Observatory/L. Calcada, retrieved here.)

When you bring a large-mass planet into close quarters with a much smaller one, something's got to give. Because of the way gravitation works, you're going to have a three-body gravitational interaction, which is one of the most difficult theoretical problems in all of physics.

But universally, what's going to happen is that there's going to be a transfer of momentum and angular momentum, and one of three things is going to happen. Either:

  1. The large planet will gravitationally capture the smaller one, turning it into a moon,
  2. The large planet will fling the small planet either violently into its Sun or violently out of the Solar System, or
  3. The large planet will collide with the small one, effectively eating it.

Sci_phys_space_slingshot_speed.png

(Image credit: BoredofStudies.org.)

In other words, these Hot Jupiters are like the psychotic eldest child that murders its younger siblings! We see that there are no rocky planets among the gas giants in our Solar System for exactly this reason. But how does this work, and why does this prevent solar systems with Hot Jupiters from having habitable planets outside of them? This is not obvious, so let me first set up the situation for you to help you get a handle on it.

As far as we understand it, all solar systems start out the same way in the very early stages: there's a central region where a star forms, accompanied by a proto-planetary disk, which will coalesce and form into planets.

Star-and-water-nasa_large.jpeg

(Image credit: NASA, retrieved here.)

But over time, planets clear the space around them. They do this, believe it or not, in the same way that star clusters all eventually end up dissipating: simple gravity. Watch this simulation of a star cluster to see what I'm talking about, and pay particular attention to the first 25 seconds of the video.

(Video credit: Simon Portegies Zwart (U. of Amsterdam) and Frank Summers (STScI).)

Notice how an occasional star just sped off from the star cluster in a random direction, even early on in the simulation? That's what gravitational encounters between more than 2 bodies do, pretty much all of the time! The physical process is called violent relaxation, which is a wonderful term that (somehow) no enthusiast has created a wikipedia entry for!

Just as the structure of the star cluster changes because of these gravitational ejections, the structure of the young solar system changes because of its gravitational interactions. These large planets can migrate, depending on how they absorb or remove each tiny mass they encounter. Some encounters move them closer towards their parent star, others move them farther away. In the case of Jupiter and Saturn, they were once significantly closer to the asteroid belt than they are today; in the case of Hot Jupiters, they clear out at least the entire habitable zone!

566413main_p1122a1_946-710.jpeg

(Image credit: NASA, ESA, and G. Bacon (STScI).)

According to research led by Eric Ford, the reason we haven't found any of these habitable, rocky planets around stars with Hot Jupiters -- even though we've found 63 of them around other stars -- is because Hot Jupiters perturb the orbits of these planetesimals in the young solar systems sufficiently so as to completely clean them out, leaving no possible rocky worlds behind!

6-planetarydisc.jpeg

(Image credit: NASA / JPL-Caltech.)

In our Solar System, our four gas giants completely cleared out the regions between about 4 Astronomical Units and about 30 Astronomical Units, where one of them is the distance between the Earth and the Sun. But if you put a Jupiter-sized planet anywhere in the inner Solar System, then all of the rocky planets wouldn't be here!

And that's why systems with exoplanet bullies in them -- Hot Jupiters, to be specific -- have no Earth-like planets in them, or rocky worlds with the proper temperatures for water. That's just one more example of the power of gravity!

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Categories: Education

The Crappy Science of Comic-Book Movies [Uncertain Principles]

Science Blogs Physcial Sciences - 8 May, 2012 - 17:18

I go back and forth about the whole question of scientific accuracy in tv shows and movies. On the one hand, I think that complaining "Explosions don't make noise in space!" is one of the worst forms of humorless dorkitude, and I'm generally happy to let bad science slide by in the service of an enjoyable story. On the other hand, though, I am a professional physicist, and it's hard to turn that off completely.

Weirdly, one thing that tends to push me toward complaining about the science is when people start doing "The Science of ______" pieces, as both MSNBC and io9 did for The Avengers, and when movie people start patting themselves on the abck for having consulted with scientists. Because, you know, if you're going to talk up the fact that there's science behind the movie, you're asking to be held to a higher standard.

And, really, most of the recent spate of comic-book movies have had scenes of technobabble that are every bit as dumb as anything produced in the days before consulting scientists. One of the worst was an exchange in The Avengers, where the team's scientists, Bruce Banner and Tony Stark, are trying to help S.H.I.E.L.D. track down Loki and his stolen energy source:

BANNER: How many spectrometers do you have?

SHIELD GUY: We have the cooperation of every university in the country.

BANNER: Tell them to put the spectrometers on the roof, and set them to detect gamma radiation.

(That's paraphrased a bit from memory.) This is one of the stupidest science-type lines I've heard in any recent movie. To give you an idea of how stupid it is, here's an analogue in more everyday terms:

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Categories: Education

Ten Years Before the Blog: 2005-2006 (Part I) [Uncertain Principles]

Science Blogs Physcial Sciences - 8 May, 2012 - 15:58

Continuing the blog recap series, we come to the "split year" of 2005-2006. The blog was initially launched in late June, so that's when I'm starting the years for purposes of these recaps, but ScienceBlogs launched in January 2006, so this year was half Steelypips and half ScienceBlogs. This post will cover the Steelypips half, June-January; I'll do the ScienceBlogs stuff in a second post, once I figure out the best way to go through those posts (the ScienceBlogs archives aren't set up well for reading straight through).

In reading through this, I was amused to discover this pan of Seed's relaunch, in which I call the magazine "Maxim for science geeks." Not quite three months later, they were paying me to write a blog... I remembered writing that, but didn't remember how close it was to the launch of ScienceBlogs.

So, what was on the blog in the second half of 2005?

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Categories: Education

For Extra Credit, Estimate Your Chances of Winning: Ballparking Giveaway [Uncertain Principles]

Science Blogs Physcial Sciences - 7 May, 2012 - 19:37

Some time back, I reviewed a cool book about Fermi problems by Aaron Santos, then a post-doc at Michigan. In the interim, he's taken a faculty job at Oberlin, written a second book on sports-related Fermi problems, and started a blog, none of which I had noticed until he emailed me. Shame on me.

Anyway, his new book is just out, and he's running an estimation contest with a signed copy as the prize. So, if you're the sort of person who enjoys Fermi problems, read his post then grab a convenient envelope and start estimating on the back. You have until June 1.

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Categories: Education

Another Week of GW News, May 6, 2012 [A Few Things Ill Considered]

Science Blogs Physcial Sciences - 7 May, 2012 - 17:33

Logging the Onset of The Bottleneck Years
This weekly posting is brought to you courtesy of H. E. Taylor. Happy reading, I hope you enjoy this week's Global Warming news roundup

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Categories: Education

Another Week of GW News, May 5, 2012 [A Few Things Ill Considered]

Science Blogs Physcial Sciences - 7 May, 2012 - 17:33

Logging the Onset of The Bottleneck Years
This weekly posting is brought to you courtesy of H. E. Taylor. Happy reading, I hope you enjoy this week's Global Warming news roundup

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Categories: Education

A Feast for your Naked Eyes: Supermoon, Solar Eclipse and Venus Transit! [Starts With A Bang]

Science Blogs Physcial Sciences - 6 May, 2012 - 02:22

"Without a wish, without a will,
I stood upon that silent hill
And stared into the sky until
My eyes were blind with stars and still
I stared into the sky." -Ralph Hodgson The next month -- from May 5th to June 5th -- brings three of the most spectacular astronomy sights possible on Earth back-to-back-to-back for skywatchers of all types, without telescopes, binoculars, or any special equipment. Tonight, May 5th, marks what's come to be known as a Supermoon, or the largest, brightest full Moon of the year.

6a0105371bb32c970b0133ed83b3bf970b-750wi.jpeg

(Image credit: Chris Kotsiopoulos at Earth Science Picture of the Day.)

Not that you'll notice, mind you, unless you've got both an incredible eye and an incredible memory. The full Moon is, by far, the brightest thing in the night sky, outshining the brightest star in the sky by a factor of around 40,000.

A supermoon, on the other hand, is only about 30% brighter than a normal full Moon.

orbit.jpeg

(Image credit: science @ NASA, retrieved from Tara Hastings at WDTN.)

The Moon, of course, orbits the Earth in an ellipse, rather than in a perfect circle. When the Moon is farther away from Earth in its orbit -- or closer to apogee -- it appears smaller in the sky, while when it's closer to Earth -- near perigee -- it appears larger. The supermoon is the one full Moon out of the year that occurs when the Moon is at its minimum distance from the Earth, and hence appears the brightest.

planetary_moon_comet_orbits.png

(Image credit: Essay Web's astronomy site.)

These differences, however, are relatively small. The full Moon at apogee is only 20% smaller than the full Moon at perigee, a difference completely un-noticeable to even a trained observer, unless you put these two images right next to one another.

287(2).jpeg

(Image credit: Marco Langbroek, the Netherlands, retrieved here.)

Having the closest, brightest full Moon of the year is a great excuse to go out and look at it, attempt to photograph it, or if you're far away enough from streetlights, enjoy the shadows cast by the moonlight.

There's nothing you can't do with a supermoon that you couldn't do with any, ordinary full Moon, but it is fun to think about why this happens.

moon.jpeg

(Image credit: Ryan, footnote #3 on Carrie Fitzgerald's site.)

The Moon makes an ellipse around the Earth, which in turn makes an ellipse around the Sun. Right now, the Moon's perigee is in the opposite direction of the Earth from the Sun, so full Moons appear as large as they're ever going to. New Moons and crescents, on the other hand, will appear somewhat smaller, as they occur closer to apogee.

But six months from now, the Earth (and Moon) will be on the other side of the Sun, so the Moon's apogee will occur close to the full phase, resulting in somewhat smaller full Moons, while new Moons and crescents will be larger. You can see NASA's apogee and perigee calculator for more information, but I think the diagram below illustrates things pretty clearly.

Fig4-2a.png

(Image credit: NASA, Fred Espenak and Jean Meeus.)

Right now, we're extremely close to position "C" in the diagram above, where the Moon's apogee (farthest from Earth) occurs close to the Sun, and the Moon's perigee (closest to Earth) occurs away from the Sun. This gives us the supermoon that you can see tonight, but fifteen days from now, it's going to give us something far more rare and special.

The Moon's apogee occurs on May 19th, and the very next day, at nearly its most distant from Earth, the Moon, Earth, and Sun will all line up, producing the spectacular and rare sight of an annular Solar Eclipse!

Ec51094.jpeg

(Image credit: Kopernik Observatory and Science Center.)

On the evening of May 20th in North America, close to Sunset, the Moon will pass in front of the Sun. But because the Moon is so close to apogee, it will actually appear ever so slightly smaller than the Sun in the sky, and thus will not be sufficiently large to block it completely!

Astute skywatchers who plan their trip right and are blessed with clear skies will get to observe the elusive "Ring of Fire" shown above. I've already written my eclipse guide for those of you preparing to join me in watching this, but there is one cheap piece of equipment I'll recommend that everyone pick up for looking at the Sun: a pair of Welder's Goggles.

weldersgoggles.jpg

For around $10 (tops), you can get a piece of equipment that will allow you to look at the Sun, whenever you want, for short periods of time. Make sure the density of the goggles is 14 or greater, and never use a telescope or binoculars with them, just your naked eye. But this is an inexpensive, easy way to allow yourself to view partial or annular eclipses (or perhaps even sunspots) whenever it strikes your fancy. (I've got my pair already.)

But there's another reason to get welder's goggles that's even more rare and spectacular than the upcoming solar eclipse. Those of you who've had clear skies in the west for the past month or two may have noticed an extremely bright object there just after sunset.

venus0505.png

(Image made with stellarium.)

This is what the night sky will look like at 9 PM at 45 degrees latitude (where I live) tonight. That bright object, fifteen times brighter than Sirius, is the planet Venus, which just achieved its greatest apparent brightness in the sky. (And appears as a gorgeous crescent with binoculars if you can focus properly!)

Venus, being an interior planet to Earth, appears brightest not when it is closest to us, nor when it's in its full phase, but rather when it's a crescent, where the combination of proximity to us and the amount it's illuminated is maximized.

venus-phase1.gif

(Image credit: Torquay Boy's Grammar School's Observatory.)

Over the coming month, Venus will descend in the sky, with progressively less and less of the planet becoming illuminated to our eyes, percentage-wise. However, Venus' angular size will increase, as the apparent diameter of the planet will increase in the sky due to it physically getting closer and closer to us.

fig1_2.gif

(Image credit: Shamefully retrieved from this website.)

Eight years ago, Venus didn't just pass interior to Earth, missing the Sun by just a degree or two; in 2004, Venus actually transited across the disc of the Sun, blocking a small fraction of the Sun's light. These transits are incredibly rare; you and I will get two in our lifetimes.

The last Venus transit before the 2004 one took place in 1882, and the next one won't be until 2117. Unless, that is, you're ready on June 5th of this year.

4815venus-transit-composite-08-06-2004-med.jpeg

(Image credit: Tonk at CloudyNights.)

It is perfectly safe to look directly at the Sun for brief periods of time with a good pair of Welder's goggles, and I've already got mine.

Where should you be to see it? That depends on where you live.

TOV2012-Fig01.png

(Image credit: Fred Espenak / NASA, retrieved here.)

Where I am in North America, the Venus transit will start at about 3:00 PM on June 5th and will continue through sunset. The entire transit won't be visible in North America, as it takes many hours to complete, but this is your one chance to witness an event like this with your own eyes.

In Europe, parts of Africa, and most of Asia, of course, you'll be able to see the transit in the morning of June 6th instead. But those of you living in Iceland get the most special treat of all: a transit that spans both sunset and sunrise!

(Video credit: user transitvenus on YouTube.)

Three major astronomical events -- the supermoon, tonight, the annular solar eclipse, on May 20th/21st, and the transit of Venus, on June 5th/6th -- all occurring within a month of one another! There's never been a better time to purchase a pair of welder's goggles, that's for sure!

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Categories: Education

Entangled In the Past: "Experimental delayed-choice entanglement swapping" [Uncertain Principles]

Science Blogs Physcial Sciences - 4 May, 2012 - 16:24

ResearchBlogging.orgEnough slagging of beloved popularizers-- how about some hard-core physics. The second of three extremely cool papers published last week is this Nature Physics paper from the Zeilinger group in Vienna, producers of many awesome papers about quantum mechanics. Ordinarily, this would be a hard paper to write up, becase Nature Physics are utter bastards, but happily, it's freely available on the arxiv, and all comments and figures are based on that version.

You're just obsessed with Zeilinger, aren't you? All right, what have they done this time? The title is "Experimental delayed-choice entanglement swapping," and it's pretty much what it sounds like. They've demonstrated the ability to "swap" entanglement so as to create quantum correlations between two photons that have never been close to one another. And they've done this in a "delayed-choice" fashion, where the decision about whether to entangle them or not is made well after the two photons they're entangling have been detected.

Oh, OK, that sounds-- Wait, what? They entangled them after detecting them? Yep. The basic scheme is illustrated by this quasi-spacetime-diagram from the supplementary material:

entanglement_swapping_diagram.jpg

The vertical axis represents time, moving into the future as you go up. They start with two pairs of entangled photons, which are sent into optical fibers. Two of these (one from each pair) go directly to detectors that record their polarizations roughly 35 ns after they were produced. The other two go into very long fibers, and are sent to a detector that either records the two original polarzations, or makes a joint measurement of the two together. If they measure the individual polarizations, the original pairs remain independent of one another, but if they make a joint measurement of the two, that entangles their states, meaning that the polarizations of the other two photons are now entangled with each other, and should be correlated.

Since these photons went into much longer fibers (104m vs. 7m), though, the entangling measurement is made after the two photons whose states are being entangled have had their polarizations measured-- about 520 ns after they were produced.

In keeping with the silly jargon of the field, the two photons that are detected immediately (Photons 1 and 4) go to detectors that are imagined to be held by people named "Alice" and "Bob." The two that are measured together to determine the entanglement (Photons 2 and 3) go to a third imaginary person named "Victor," and it's Victor's measurement that determines everything.

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Categories: Education

Space Chronicles by Neil deGrasse Tyson [Uncertain Principles]

Science Blogs Physcial Sciences - 3 May, 2012 - 16:35

I was tremendously disappointed and frustrated by this book.

This is largely my own fault, because I went into it expecting it to be something it's not. Had I read the description more carefully, I might not have had such a strong negative reaction (which was exacerbated by some outside stress when I first started reading it, so I put it aside for a few weeks, until I was less mad in general, and more likely to give it a fair reading). I'm actually somewhat hesitant to write this up at all, for a number of reasons, but after thinking it over a bit, I think I have sensible reasons for being disappointed in the book, and it's probably worth airing them.

As mentioned in yesterday's post about "Big Science", this is a book whose central message is that we ought to be spending more money than we are on space exploration in order to boost science as a whole. And when I saw Tyson promoting this on either the Daily Show or the Colbert Report, I was excited by the idea. As anybody who's been reading the blog for any length of time knows, I'm all in favor of bringing science to a broader audience (which is why I write books where I discuss physics with my dog). While I'm skeptical the space is the most effective tool for getting the job done, I'm prepared to hear a good argument for that, and Tyson seemed like just the guy to do that: to provide a clear and coherent vision of what space exploration ought to be in order to serve as a driver of science in general.

But this is not that book. Instead, it's a collection of... stuff. Some essays, some speeches, some interview transcripts, a whole bunch of Twitter posts. Collectively, they're all about space exploration as a general matter, and many of the individual pieces are as good as you would expect. But it's not a sustained and coherent argument. And that's a missed opportunity.

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Categories: Education

Dog Physics: Obsessive Update [Uncertain Principles]

Science Blogs Physcial Sciences - 3 May, 2012 - 15:51

A few more links that have turned up of people talking about either How to Teach Physics to Your Dog and How to Teach Relativity to Your Dog:

  • Andrew Johnston has a review of the UK edition, praising it because "it's bang up to date, and goes beyond the basic quantum concepts into more complex areas like decoherence, entanglement and quantum teleportation," which I like to see because that's one of the things I especially wanted to do.
  • Natasha Zaleski, a grad student, has a review of How to Teach Relativity to Your Dog, which is good but not great, because it hit the usual failure mode: the talking-to-the-dog thing wore thin for her. Which is, of course, the danger of the whole talking-to-the-dog conceit.
  • The Polish edition is out-- I got my author copies, which are very nice. This has led to a review in a pop-culture magazine, between Steig Larsson and Terry Pratchett. Google Translate makes hash of it, in part because it does a literal translation of my surname, leading to sentences like "Even so, Eagle shows the world a lot of physics accessible, than does the bulk of textbooks for physics."
  • The vanity search also turned up a mention of the books in the Raised Indoors podcast-- one of the hosts bought both from Amazon in Canada (thanks!), but hasn't yet read them. Hope you like them. The podcast itself is a general-interest pop-culture thing, and the Clive Cussler rant is pretty amusing.

And that's the latest from the vanity search.

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Categories: Education

Black Holes don't eat as much as they accrete! [Starts With A Bang]

Science Blogs Physcial Sciences - 3 May, 2012 - 03:56

"This is the way I wanna die. Torn apart by angry fans who want me to play a different song." -Regina Spektor You're familiar with the classic picture of a black hole: a dark, dense region at the center from which no light can escape, surrounded by an accretion disk of matter that constantly feeds it, shooting off relativistic jets in either direction.

accretion-big.jpeg

(Image credit: University of Warwick, retrieved from here.)

This is a pretty accurate picture of active black holes. But most black holes aren't active, and of the ones that are, they aren't active most of the time!

Most people think of black holes as marauders, gobbling up whatever poor stars happen to get in their way. You very likely have a picture of a black hole as though it behaves like a great cosmic vacuum cleaner, sucking up anything that dares get too close to it.

(Video credit: NASA / GSFC, via YouTube.)

I can't fault you for thinking that; this is a genuine NASA video, and the picture that some very smart people have been painting for you for a long time. But that isn't quite how the Universe works.

So, how does it work? When any object falls in close to a black hole, it experiences different forces on different parts of the object. We call these forces tidal forces, because they're the same types of gravitational forces that cause the tides we experience here on Earth!

Field_tidal.png

(Image credit: Barger and Olsson.)

Only, in the vicinity of a black hole, the tidal forces are much stronger than we experience on Earth. They are, in fact, much stronger than Jupiter's innermost moon, Io, experiences, and those forces are powerful enough to constantly tear Io apart, making it the only volcanically active moon in the Solar System!

No, when you get close to a black hole, you get stretched at either end so severely, and compressed in the middle so thinly, we call the process spaghettification, one of the greatest astrophysics words ever invented!

tidal_forces.gif

(Image credit: John Norton at Pittsburgh.)

But "falling in" to a black hole, like illustrated above, practically never happens! Space is simply too big, and even for supermassive black holes -- like the multi-million-solar-mass behemoth at the Milky Way's center -- the event horizon is too small. Most stars and objects that pass nearby to a black hole simply do what all other objects in the Universe do.

Gravitate! (Ha ha ha ha haaaaa!)

2011orbits_animfull.gif

(Animation credit: UCLA Galactic Center Group / Andrea Ghez.)

Remember that space is huge, and that getting within a paltry 0.001 light years of our galaxy's supermassive black hole won't even disrupt the passing star, much less "vacuum it up," as you might have thought.

"But what if the star does get close enough," you ask, "then what happens?"

Well, they've actually gone and run the simulation properly, and I've got the results, here, to show you!

(Video credit: NASA, S. Gezari (Johns Hopkins), and J. Guillochon (UCSC).)

Note how, first, the star gets completely ripped apart by these intense tidal forces! But rather than acting like a vacuum cleaner and sucking it all up, most of the mass from this star doesn't get devoured at all; quite to the contrary, most of it gets ejected back out into the space around the black hole! It's only a small fraction of the original that gets swallowed, but that's totally sufficient to take a quiet, supermassive black hole, and bring it back to life!

And we know this, because we just observed a super distant galaxy -- more than 2 billion light years distant -- just become ultra bright thanks to its supermassive black hole sneaking a bite out of an unlucky passerby! Let's take a before-and-after look.

Galex_Pan-STARRS.jpg

(Image credit: NASA, S. Gezari, A. Rest, and R. Chornock, as are the next two.)

The above images, from GALEX (in the Ultraviolet) and Pan-STARRS (in the visible/IR), show this distant galaxy shortly before it started snacking on its newly accreted material. The images are low-resolution because GALEX and Pan-STARRS focus on grabbing very wide fields-of-view; when you're looking for very rare occurrences like this, you need to grab as much of the deep sky as possible!

So, that was 2009. But the next year...

but_the_next_year.jpg

The galaxy has brightened by a factor of around 350 in the Ultraviolet, and the visible/IR image has turned much bluer, an indication of the extraordinarily high energies being belched out by this suddenly noisy galaxy!

Taking a look at the before-and-after images together, you can really see the difference.

hs-2012-18-b-print.jpeg

But don't be fooled by the vacuum cleaner description; it's not eating the entire thing that ran into it! This is, in fact, something that we may see happening for much smaller black holes that are much closer to us; the nearby galaxy Messier 83 just had a very similar outburst from a much smaller black hole!

m83_4panel.jpeg

(Image credit: Optical: ESO/VLT; Close-up - X-ray: NASA/CXC/Curtin University/R.Soria et al., Optical: NASA/STScI/Middlebury College/F.Winkler et al.)

Black holes aren't giant leviathans, devouring anything that comes nearby, but nor are they dainty, steady nibblers on objects that orbit. Rather, black holes are wild, violent and inevitable, tearing anything that dares approach too closely into shreds, but coming away with a snack-sized meal whose first bite makes quite an impression!

Now, if you'll excuse me, all this black hole talk has made me hungry! Where did I put the spaghetti...

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Categories: Education

Trickle Down Science [Uncertain Principles]

Science Blogs Physcial Sciences - 2 May, 2012 - 20:53

A week or so ago, lots of people were linking to this New York Review of Books article by Steven Weinberg on "The Crisis of Big Science," looking back over the last few decades of, well, big science. It's somewhat dejected survey of whopping huge experiments, and the increasing difficulty of getting them funded, including a good deal of bitterness over the cancellation of the Superconducting Supercollider almost twenty years ago. This isn't particularly new for Weinberg-- back at the APS's Centennial Meeting in Atlanta in 1999, he gave a big lecture where he spent a bunch of time fulminating about what idiots politicians were for cancelling the project. If anything, the last decade and a bit has mellowed him somewhat.

Sort of in parallel with this, I've also been reading Neil deGrasse Tyson's latest book, Space Chronicles (I say "sort of" because I actually stopped reading it for a couple of weeks, because I found it maddening for reasons that I may go into in another post). This is a collection of things from other sources that collectively sort of advances the argument that we need to spend flipping great wodges of cash on space exploration, for the good of science and society as a whole.

While these aren't directly related to each other-- and, indeed, are somewhat in conflict, as Weinberg has no use for manned space flight-- they're both making a similar argument: that we should be spending money on Big Science projects, because they're important for science as a whole. Which is fine, to a point-- I'm all in favor of increasing the amount of money we spend on scientific research-- but I can't help thinking that it's awfully easy to make this argument when the Big Science projects just happen to fall very close to your area of interest.

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Categories: Education

Clock Synchronization Done Right: "A 920-Kilometer Optical Fiber Link for Frequency Metrology at the 19th Decimal Place" [Uncertain Principles]

Science Blogs Physcial Sciences - 2 May, 2012 - 17:05

I've been busily working on something new, but I'm beginning to think I've been letting the perfect be the enemy of the good-enough-for-this-stage, so I'm setting it aside for a bit, and trying to get caught up with some of the huge number of things that have been slipping. Which includes getting the oil changed in my car, hence, I'm sitting in B&N killing time, which is a good excuse to do some ResearchBlogging.

ResearchBlogging.orgLast week was a banner week for my corner of physics, with three really cool experiments published. Two of those are on the arxiv, which means I can use images from the paper (but those take longer to write). The third was in Science and isn't available in preprint form, and since the AAAS are bastards about permissions, and I'm not paying them $30 for the sake of a blog post, we'll do that one first.

The paper in question has the incredibly sexy title "A 920-Kilometer Optical Fiber Link for Frequency Metrology at the 19th Decimal Place", and got a pretty good write-up in Physics World, but there's still room for some Q&A:

Seriously? Optical fibers and frequency metrology? What do those even mean? Seriously. This is a significant advance for people who care about precision measurement of time. The authors took two ultra-precise atomic clocks in labs at opposite ends of Germany, and were able to compare their frequencies at the level of a few parts in 1019. That's 0.0000000000000000004 times the original frequency, or, since they started with an optical frequency, 0.00008Hz out of 194,000,000,000,000.

OK, I admit, that's a lot of zeroes. But why does that matter? Isn't the whole point of ultra-precise atomic clocks that they all work exactly the same way? Why do you need to compare them? All atomic clocks using a given type of atom have the same basic frequency, but not all clocks are equally well made. The only way to determine the performance of a new one is to compare it to one you know works, but they're also not very portable, so you need to be able to do the comparison remotely.

There's also the fact that the local conditions for different clocks will be different, which can lead to some small shifts in the frequency due to things like general relativity, which means you can study some interesting physics using a distributed network of clocks. You can also check to see if the constants of nature are changing by comparing clocks based on different atoms, and again, these are not easy to make or move around, so being able to reliably do the comparison over long distances is a bug deal.

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Categories: Education

You're not from around here, are you? [Starts With A Bang]

Science Blogs Physcial Sciences - 2 May, 2012 - 02:35

"A journey is a person in itself; no two are alike. And all plans, safeguards, policing, and coercion are fruitless. We find that after years of struggle that we do not take a trip; a trip takes us." -John Steinbeck Here on Earth, we all get to enjoy the delight of being located in an extremely fortuitous place in our Solar System. Not just today, mind you, but billions of years ago, when the Solar System's planets were first forming!

6-planetarydisc.jpeg

(Image credit: NASA / JPL-Caltech, retrieved from Jodrell Bank CfA.)

Located close enough to our Sun, when the Earth first formed, like our neighbors Mercury, Venus and Mars, we were chock full of heavy elements. Not just the carbons, nitrogens and oxygens that abound on all the known worlds, but important ones much higher up on the periodic table, including silicon, sulphur, iron, nickel, tin, lead, and even the radioactive uranium!

This might not sound so special to you, but our world would be a lot more boring if we had formed farther from the Sun. See for yourself:

Model%20Solar%20System.gif

(Image credit: Russ Meyer, using data from NASA.)

Jupiter and Saturn aren't simply less dense than Earth is because they retained all that excess hydrogen that our wimpy gravitational field couldn't hold. Although that's true, they're also made out of elements that are intrinsically less dense!

We can identify where an object found anywhere in the Solar System -- including meteorites that fall to Earth -- simply by examining what they're made out of.

full-moon-horizon-125606main-iss010e18583-ga.jpg

(Image credit: NASA, retrieved from National Geographic.)

One of the most spectacular applications of this knowledge came when we first journeyed to the Moon. For the first time, we'd be able to analyze rocks from the Moon and their chemical composition! What we found was simultaneously profound and the most boring thing imaginable.

hasselblad.jpeg

(Image credit: NASA / Apollo 11, retrieved from here.)

Because the Moon is made out of the same stuff that the Earth is!

Before you start saying, "Duhhhhh," as some of you are wont to do, let's remember that it didn't have to be this way. We need only look at our nearest moon-ed neighbor.

marsmoons_schedler_220803labeled.jpeg

(Image credit: Johannes Schedler / Panther Observatory, retrieved here.)

Because Mars' two moons, Phobos and Deimos, are not made out of the same stuff Mars is! They formed significantly farther out in the Solar System, originating in the asteroid belt. Only a chance encounter with another body (probably Jupiter) flung them in to the inner Solar System, where they were gravitationally captured by the red planet!

If it happens for Mars from the asteroid belt, you may be wondering about that other, even bigger belt in our Solar System, and what the possibilities might be from there.

image0032.jpeg

(Image credit: Don Dixon / Cosmographica.)

I refer, of course, to the Kuiper Belt, the band of leftover proto-planetesimals from the formation of our Solar System. These small, icy objects are only about a third the density of Earth, but are more dense than the gas giants that lie interior to them.

If the asteroids could be flung towards the inner, rocky worlds due to the gravitational influence from Jupiter, it stands to reason that these Kuiper Belt objects could similarly be flung inwards thanks to Neptune.

Wherefrom.jpeg

(Image credit: source unknown, retrieved from clowder.net.)

There are some dead giveaways that your object isn't from the same part of the Solar System as its initial planet is. There's the elemental composition / density argument, of course, but simply via random chance, 50% of these objects that get captured will wind up revolving around their planet the wrong way. One obvious guy like this is Neptune's largest moon, Triton.

triton.jpeg

(Image credit: Voyager Spacecraft, S. Albers / NOAA / GSD.)

Triton is maybe the easiest one; he's so large that if he were still in the Kuiper belt, he'd be the largest object there, dwarfing (burn!) both Pluto and Eris!

But there are others, elsewhere, that don't quite look like they belong. And a Saturnian mystery may, in fact, be on the cusp of being solved thanks to this idea.

iapetus-bright.jpeg

(Image credit: Cassini / NASA / JPL-Caltech.)

This is Iapetus, one of Saturn's moons, looking like it always does: like it came out on the wrong side of a trip through the mud. Iapetus does all the moon-like things correctly: it revolves the right way around Saturn, it's got the right density for its spot in the Solar System, its surface is even made of the same elements -- as far as we can tell -- as it ought to be.

Except for that muddy mess that discolors one of its face. What's going on here? It turns out Iapetus isn't alone.

nfi_18934_034673400_1254915677.jpeg

(Illustration credit: AP / NASA, retrieved from here.)

A giant, diffuse outer ring, well beyond the Saturnian rings you're used to, pollutes Iapetus' orbit. As the tidally-locked moon speeds around Saturn, these grains from the ring smack into Iapetus, discoloring it like billions of bugs on a windshield.

The question, of course, is where did this ring come from? Because it isn't Saturn. The answer is much more fun than that!

148216main_image_feature_565_ys_4.jpeg

(Image credit: Cassini / NASA / JPL-Caltech.)

Say hello to Phoebe, Saturn's very suspicious moon, located in the same vicinity as both this outermost ring and Iapetus. Phoebe is full of craters, a different color and elemental composition than the other moons, and -- this is a big and -- it revolves around Saturn the wrong way!

In other words, this outsider came all the way from the Kuiper Belt to become a moon of Saturn! And the journey was no picnic for Phoebe, either.

7189_17162_1-4f9ac73-intro-thumb-640xauto-33446.jpeg

(Image credit: NASA / Cassini / Caroline Porco / CICLOPS.)

Those craters on its surface are from a lifetime of bombardment! The once-spherical Phoebe has lost a lot of its mass, and that's almost certainly where the material that makes up both the outermost ring and the diffuse discoloring of Iapetus comes from!

Let this be a lesson to all of you: if you want to be adopted by another planet, make sure you orbit the same direction as everything else! In the meantime, know that objects from the asteroid belt or Kuiper Belt could come in at any time, and could even become our planet's next additional moon!

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Categories: Education

Ten Years Before the Blog: 2004-2005 [Uncertain Principles]

Science Blogs Physcial Sciences - 1 May, 2012 - 20:33

Delayed again by the need to do actual, you know, work, here's a look back at the third year of this blog's existence. You can also read posts covering year one and year two.

2004-2005 was the last complete year before the move to ScienceBlogs in January of 2006, after which the making of these posts will become more complicated, because my posting rate went way up. For this year, though, I was still sticking to one post a day, and the blog had settled into a pretty decent groove.

The year did feature a brief foray into silly physics-related fiction, which might possibly be called a precursor to the books, and a local tv appearance related to the election of 2004 (which I had otherwise tried to blot from memory. Ye gods, that was depressing to relive). This was back before YouTube became really big, so I didn't include a clip in the post, but I added it a few years later, so you can see me talking about lying with statistics for a few seconds.

Specific posts of interest, by tagline category:

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Categories: Education

Thank You from the USA Science and Engineering Festival! [USA Science and Engineering Festival: The Blog]

Science Blogs Physcial Sciences - 1 May, 2012 - 18:54

The 2012 USA Science and Engineering Festival was a huge success this past weekend! More than 150,000 attendees battled the rain, traffic and crowds to celebrate science at the Convention Center!

Start of Festival.jpg

The Festival would not have been possible without the hard work of our amazing volunteers! Over 750 volunteers dedicated their valuable time and showed incredible patience and enthusiasm during their shifts at the Festival. We are so grateful to ALL of you! We received wonderful feedback about our exhibitors and the amazing hands-on activities. Exhibitors made each person feel welcome and thoroughly explained their activities to attendees of all ages. And finally, we are so thankful for the extraordinary generosity of our sponsors and Festival Host Lockheed Martin.

Volunteer

With over 3,000 exhibits and 150 stage shows, there are so many wonderful Festival moments to highlight. Our Festival Host Lockheed Martin surprised us all with a few last minute additions including presentations by US Olympic Speed Skaters and cast members of NCIS Los Angeles. R2D2 made a special appearance along with our science celebrities including astronauts, Bill Nye, the Mythbusters, Mayim Bialik and NAO the robot! It was quite apparent that kids of all ages explored their "inner scientist" and had an amazing time at the Festival!

einstein.jpg

Bill Nye the Science Guy delighted crowds all weekend long! Watch this clip courtesy of The Epoch Times:


We received quite a number of comments and suggestions via email, twitter and Facebook. Twitter followers were tweeting and posting pictures all weekend long! We greatly appreciate all of the feedback and will definitely take it all into consideration for the next celebration!

Here are some of our favorite comments:

C.N. writes: "I can't say enough good things about this event! It was wonderful to see so many children so engaged with science, and clearly having fun at the same time! This was probably the best children's festival I have ever attended. Please bring it back to DC next year!"

C.J. writes: "What a FABULOUS Festival! You guys outdid yourselves. The exhibits and volunteers were wonderful. Loved all the cool giveaways, especially Lockheed Martin's blue lighty necklace. Wish we could have seen more... I too am home resting my feet! Thank you!"

NAEYC writes: "It was wonderful to see so many families at the Festival, and teachers who came from a distance to get ideas for their program."

Exhibitor SEM Link writes: "Thank you USA Science & Engineering Festival for allowing SEM Link to be a Partner and Exhibitor for the 2nd US Science and Engineering Festival Grand Finale and Expo. We had a blast and look forward to participating in next year's festival."

J.B. writes: "Whoever came up with the idea of the Science Festival should be congratulated. It made science fun for my children to learn about."

And one of the best comments we received in response to the enormous crowds that attended the Festival was from L.Y. "How nice to see people excited about science and engineering! Nice switch from what people usually complain about.....lines, crowds at concerts, sporting events, etc! Maybe we are making progress!"

Festival Fun.jpg

Once again, we appreciate all of the feedback and please continue to share your favorite Festival moments on our Facebook page! Stay connected with the Festival and thank you all again your support and enthusiasm! We hope that the Festival inspired you to see that with hard work, dedication and of course the desire to dream big the possibilities are endless!

Enjoy this wonderful recap of Day 1 of the Expo by Festival Sponsor ENGINEERING.com:

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Categories: Education

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