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A challenge for you [Greg Laden's Blog]

Science Blogs Physcial Sciences - 28 March, 2012 - 17:10

What are we looking at here? Your answer will depend on the angle with which you approach the problem.
Tilt.jpg

hat tip: Sarah Moglia.

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Categories: Education

The Hubble Treasure Hunt [Dynamics of Cats]

Science Blogs Physcial Sciences - 28 March, 2012 - 06:55


Many of the Hubble Space Telescope images have never been looked at.
You can now browse the archives and win valuable prizes for finding cool new pics.

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Categories: Education

Why is there something instead of nothing? [Starts With A Bang]

Science Blogs Physcial Sciences - 28 March, 2012 - 04:30

"Think binary. When matter meets antimatter, both vanish, into pure energy. But both existed; I mean, there was a condition we'll call 'existence.' Think of one and minus one. Together they add up to zero, nothing, nada, niente, right? Picture them together, then picture them separating--peeling apart. ... Now you have something, you have two somethings, where once you had nothing." -John Updike Looking out at our Universe, at the myriad of stars, galaxies, and, well, "stuff" in our Universe, it's hard not to ask yourself where it all came from.

201103_VirgoGCM_andreo.jpeg

(Image credit: Rogelio Bernal Andreo, retrieved from APOD.)

When we look out at the Universe, each point of light that's out there, whether a planet, star, galaxy, cluster of galaxies or something even bigger, contains the entire history of the Universe as part of its story.

There's a great cosmic spider-web of structure that's traced out by the galaxies in the Universe, with each pixel of light representing the location of a single galaxy.

2dFzcone_dots.gif

(Image credit: 2dF Galaxy Redshift Survey.)

When we consider our Universe, sure, it's full of dark matter and dark energy; that's how you make the structure we observe today. Even if we allowed ourselves to modify the laws of General Relativity, there's simply no other way to reproduce/recreate the Universe we have today.

Looking at the matchup between simulations and observations, the cosmic web of great clusters, filaments and empty voids fills the entire modern Universe.

(Video credit: V. Springel et al. (2005), Millenium Simulation.)

How did they get there? It took the billions of years the Universe has been around, the irresistible force of gravity, and the runaway growth of structure in the expanding Universe to bring it all together.

The beautiful simulation below, by Ralf Kähler, scales out the expansion of the Universe so that we can visualize just how matter -- both normal and dark -- collapses over time into galaxies, filaments and clusters.

(Visualization: Ralf Kähler and Tom Abel; Simulation: Oliver Hahn and Tom Abel (KIPAC).)

But it's the normal matter -- the protons, neutrons, and electrons -- that produce the visible light we pick up with our telescopes. The stars and galaxies that we see are all, as best as we can tell, made out of normal matter. And yet, this, itself, is a puzzle.

Because the laws of physics don't allow you to create or destroy matter without also creating or destroying an equal amount of antimatter!

pair_production_and_annihilation.jpeg

(Image credit: Addison-Wesley, retrieved from J. Imamura / U. of Oregon.)

At least, this is true experimentally and observationally. But it couldn't always have been true, otherwise the Universe would have an equal amount of antimatter in it to the matter that's present.

And it doesn't. In fact, if there were an equal amount of antimatter created to the amount of matter we presently have in the Universe, the Universe would be so sparsely populated that there'd only be about one subatomic particle per cubic kilometer.

It would be less than one-billionth as dense as the Universe we have today.

So let's go back to the very early stages of the Universe, when it was filled with a hot, dense plasma, with equal amounts of matter and antimatter, and see if we can't make the Universe we have today.

plasmas.032-001.jpg

(Image credit: me, background by Christoph Schaefer.)

Against the background of this hot, dense, fully ionized plasma, an equal quantity of particles and antiparticle flit back-and-forth. They collide with one another, annihilating, while other particles, like photons, interact with one another, producing equal amounts of matter and antimatter when they do.

If the Universe were of a constant size, a constant temperature, and all the particles and antiparticles in it were stable, it would be impossible to create more matter than antimatter, or vice versa. But in our Universe, none of those things are true!

Abrams35c.jpeg

(Image credit: Ben Moore, retrieved from N. Abrams and J. Primack.)

The Universe is expanding and cooling, and what this means is that -- when the temperature drops below a certain point -- you can no longer create matter/antimatter pairs as quickly as you destroy them! Why's that? Because E = mc2, and once the energy of your Universe drops below the mass necessary to create the particles/antiparticles you're looking to make, the ones that already exist simply go away.

How do they go away? They annihilate away, as only matter and antimatter can. But as they do, it gets more and more difficult for the matter and antimatter particles to find one another. Because the Universe is expanding, the density is dropping, and these particles/antiparticles are disappearing, you reach a point where they can no longer find one another. This "leftover" stuff you get, after all the annihilation the Universe can muster, is called freeze-out.

fig8.gif

(Image credit: Ned Wright's Cosmology Tutorial.)

Getting this "frozen out" stuff is a consequence of the Universe being out of thermal equilibrium. For example, for example, at some point, you're going to be left with a Universe that contains a bunch of muons and anti-muons. Like most particles we know how to make, these are unstable, and will decay. For most particles/antiparticles, like muons/antimuons, this isn't a big deal. Whatever the particle decays into, the antiparticle will decay into the anti-counterpart, giving you a net gain of nothing.

But some particles are fundamentally different from their antiparticles, and this difference can create more matter than antimatter in the Universe! Here's how.

qqbar.032-001.jpg

Let's imagine the Universe is filled with a new kind of unstable particle, the positively-charged Q+, and its antiparticle, the negatively-charged Q-. Because of certain conservation laws, they have to have the same mass, the opposite charge, and the same total lifetime.

But they don't have to be the same in every way. Let's say the Q+ can decay into either a proton and a neutrino, or into an anti-neutron and a positron. That means the Q- must be allowed to decay into an anti-proton and an anti-neutrino, or into a neutron and an electron.

decay.033-001.jpg

Although this looks weird, because you sometimes have matter decaying into antimatter and antimatter decaying into matter, there are three important things about this type of decay:

  • it allows you to violate the conservation of baryon number. (That is, the number of protons + neutrons combined.)
  • This is allowed by the standard model, so long as the number of baryons minus leptons is conserved, and
  • it can, if things work out correctly, create more matter than antimatter.
In addition to being out-of-equilibrium, there's one more thing that we need.

conserve2.jpg

If the percentage of the Q+'s that become protons and neutrinos is the same as the percentage of Q-'s that become anti-protons and anti-neutrinos, this won't help you at all. The protons and anti-protons will be equal in number, and you won't create any more matter than antimatter.

Same deal with the anti-neutrons/positrons and the neutrons/electrons. But although it's possible that these individual percentages are equal, it isn't mandatory. The other possibility is -- and this happens in nature -- that particles will prefer one type of decay, while antiparticles will prefer a different type!

violate.033-001.jpg

If this happens, then the Q+'s would make more protons and neutrinos than the Q-'s would make anti-protons and anti-neutrinos, while the Q-'s would make more neutrons and electrons than the Q+'s would make anti-neutrons and positrons.

Looking solely at the protons/neutrons/anti-protons/anti-neutrons that result from this decay, what would we wind up with?

leftover.034-001.jpg

More matter than anti-matter! In fact, so long as you fulfill these three famous criteria:

  1. Out-of-equilibrium conditions,
  2. Baryon-number-violating interactions, and
  3. C- and CP-violation (the differences in decays, above),
you not only can create more matter than antimatter (or vice versa), but an asymmetry is inevitable. And since something like this is required to create more matter than antimatter in the Universe, and that's the Universe we have, this is why there's something instead of nothing!

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Categories: Education

Quantum Musical Interlude [Uncertain Principles]

Science Blogs Physcial Sciences - 26 March, 2012 - 22:37

The title says it all: an animated video of Heisenberg singing about the Uncertainty Principle:

So, you know, there's that. It's pretty good, but he's no Feynman:

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Categories: Education

Treating Big Molecules Like Electrons: "Real-time single-molecule imaging of quantum interference" [Uncertain Principles]

Science Blogs Physcial Sciences - 26 March, 2012 - 17:05

ResearchBlogging.org Richard Feyman famously once said that the double-slit experiment done with electrons contains everything that's "'at the heart of quantum physics." It shows both particle and wave character very clearly: the individual electrons are detected one at a time, like particles, but the result of a huge number of detections clearly traces out an interference pattern, which is unambiguously a wave phenomenon. The experiment has been done lots of times, but a particularly nice realization of it comes from Hitachi's R&D department, where you can see both still images and video of their experiment, with arriving electrons making little dots on a fluorescent screen.

Of course, an interesting question in all this is just how big you can make some material object and still see interference. I've research-blogged before about experiments in Austria using big floppy organic molecules with up to 430 atoms. Those didn't have the "arrive one at a time" feature of the best electron interference experiment, though. But now, the same group in Austria has a new paper in Nature Nanotechnology doing just that. The paper is at least temporarily free to access, making it a good target for a new ResearchBlogging post.

OK, so what's interesting about this again? If people already did interference with large molecules, and already did interference with electrons, how is this in a Nature journal? Well, the previous interference experiments using molecules used slow detectors that had to collect signal for a long time. They couldn't see an individual molecule showing up at a particular spot at a particular time. This leaves open the possibility that what they see is some collective effect of lots of molecules going through their apparatus at the same time. What they did here detects the individual molecules, one at a time, closing that notional loophole, and making this experiment essentially equivalent to the double-slit experiments with electrons. You can see the buildup of the pattern in this image:

single_molecule_interference.jpg

(Figure 3 in the paper, also used in their press release)

Each individual dot in the figure represents a single molecule detected at the end of their apparatus. Images a)-d) show the slow buildup of the pattern from many individual detections, and part e) is the end result. You can compare this to the corresponding figure from Hitachi's electron experiment:

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Categories: Education

Another Week of GW News, March 25, 2012 [A Few Things Ill Considered]

Science Blogs Physcial Sciences - 26 March, 2012 - 16:25

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

Fact or Friction: Slow Earthquakes [The Weizmann Wave]

Science Blogs Physcial Sciences - 26 March, 2012 - 10:05

Earthquakes are once again in the news, this time in Mexico. Although it is only the biggest quakes that make international headlines, we might take a minute to contemplate other quakes - the ones you'll never feel. So-called "slow" or "silent" earthquakes slip so softly they don't even show up on regular seismographic equipment.

As the name implies, slow quakes release the energy built up along the fault over hours or even days, as opposed to mere seconds for a fast, shaking quake. So why should we care about what happens in earthquakes that even scientists have barely noticed? For one thing, says the Institute's Dr. Eran Bouchbinder, slow quakes are likely to be a part of the larger seismic picture, possibly releasing stresses from one part of a fault by adding to the stress on another. There is some evidence that certain slow earthquakes might precede the big, fast ones.

Are slow earthquakes really different from fast ones? Bouchbinder thinks that the answer may possibly be: yes. He and his team have developed a new model for sliding friction - friction between two moving plates, for instance - that suggests an explanation for the physics of slow quakes.

lossy-page1-536px-Hayward_fault_california.tif.jpg
Composite satellite image reveals a slow earthquake on the Hayward fault in California (Image: NASA)

Here it is in a tiny nutshell: Earthquakes - of any type - occur when the shear forces pushing the tectonic plates past each other surmount the force of friction that is holding them in place. In a big quake, the frictional interface fails very quickly, releasing huge amounts of energy in a short period of time. The speed of failure is limited by the speed of sound - the very same speed at which waves propagate through the earth's crust, shaking everything above. But the slow quakes seem to be different - the speed of sound may not influence them, says Bouchbinder. The model he and his team propose for movement at frictional interfaces might explain the underlying mechanics without sound wave physics. Instead, it implies that friction and sliding speed have a more complex relationship than previously thought, so that friction might increase at speeds where it was thought to decrease. For more on the model, go to our online article or check out the paper in Geophysical Research Letters.

The new model, by the way, might also help explain the dynamics of other frictional interfaces, e.g. between car tires and roads, or lend insight into nano-mechanics, among other things.

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Categories: Education

Science Fantastic, Sales by SteelyKid [Uncertain Principles]

Science Blogs Physcial Sciences - 25 March, 2012 - 14:39

I had a signing yesterday at the Barnes & Noble in Vestal, NY, which drew a smallish crowd mostly of friends and family. SteelyKid came, of course, and while she spent most of her time bopping about other parts of the store, she came over to the signing area while I was signing books for people after reading a bit. They had a big stack of copies of How to Teach Relativity to Your Dog, and she started picking them up and handing them to me.

"No, honey," I said, "Those are for other people. Give them to somebody else." So she happily ran one over to my mother. And then to one of my aunts. And then I stopped paying attention.

Until my mother came over to return a copy to the pile, and told me that SteelyKid had been running up to total strangers and trying to give them copies of my book.... Which was really a brilliant marketing strategy, on reflection. I should've tried that earlier...

Also yesterday, I was on the Science Fantastic radio show with Michio Kaku. The interview was taped this past Monday, and appears in the second hour of the three-hour show (the first hour had Ian Stewart talking about his new book, the third hour was questions from callers). If you didn't hear it, but would like to, there are a whole bunch of stations carrying it that run it today, many of them offering audio streams over the Internet (which is how I listened to it, and recorded my bit...). I think it went pretty well, but I'd be happy to hear from somebody else.

And that's your How to Teach Relativity to Your Dog publicity update for today.

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Categories: Education

Scientific Commuting: Some Answers to "How Much Faster?" [Uncertain Principles]

Science Blogs Physcial Sciences - 23 March, 2012 - 19:50

So, the previous post poses a physics question based on some previous fooling around with modeling my commute:

A car starts from rest at the beginning of a straight 1km course, accelerates up to some speed, cruises at constant speed for a while, then decelerates to a stop at the end of the course. A second, identical car does the same course, but decelerates to a stop at the halfway point. It then immediately accelerates back to its cruising speed, and then decelerates to a stop at the end of the course.

How much faster does the second car have to go in order to complete the course in the same time as the first car?

This is deliberately somewhat vague, because I want to leave room for some discussion of what are reasonable values for cruising speed and acceleration, and so on. For the purposes of attempting to answer this, I used values that were moderately realistic and also mathematically convenient: A cruising speed for the first car of 16 m/s, and an acceleration (both speeding up and slowing down) of 4 m/s/s.

So, how do you work this out mathematically? Well, if you look back at the first post I did modeling this, you find that the time required to make the trip in N stages is:

commute5.png

Here you see the reason why I didn't end up doing anything with this last fall: this is an equation that's a little tricky for intro physics students, whose level of math preparation isn't always what we would like it to be. To get an algebraic solution, you would need to take this equation with N=1 and set it equal to the equation for N=2 but a different final speed, and solve for that final speed. That's more math than I really want to wrestle with, and I guarantee it would be a disaster for most of our intro students.

However, this is an easy enough equation to plug into a computer and generate solutions, which you can plot as nice graphs. So here are a few graphs giving the answer for the situations I looked at:

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Categories: Education

Scientific Commuting: How Much Faster? [Uncertain Principles]

Science Blogs Physcial Sciences - 23 March, 2012 - 16:17

Back in the summer, I did a post mathematically comparing two routes to campus, one with a small number of traffic lights, the other with a larger number of stop signs, and looked at which would be faster. Later on, I did the experiment, too.) Having spent a bunch of time on this, I was thinking about whether I could use this as a problem for the intro physics class. I decided against it last fall, but something else reminded me of this, and I started poking at it again.

So, I played around a bit with some numbers, and came up with the following possible framing for a question. I'll throw this out here, to see what people think, then I'll post some solutions in a few hours.

A car starts from rest at the beginning of a straight 1km course, accelerates up to some speed, cruises at constant speed for a while, then decelerates to a stop at the end of the course. A second, identical car does the same course, but decelerates to a stop at the halfway point. It then immediately accelerates back to its cruising speed, and then decelerates to a stop at the end of the course.

How much faster does the second car have to go in order to complete the course in the same time as the first car?

Obviously, this requires some assumptions about the speed and acceleration of the car, which might make for some useful discussion. You can find the necessary math at the first link above, if you want to work it out. For a class using a clicker-type response system, I'd turn it into a poll question like so:

How much larger must the cruising speed of the second car be to finish in the same time as the first car?

So, we'll leave this up for a while, and then this afternoon, I'll post some analysis. Feel free to share your thoughts about appropriate assumptions, etc. in the comments. Or to suggest ways to re-cast the problem that might be more useful. This is classical physics, though, so you don't get to choose more than one option.

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Categories: Education

How to Teach Relativity to Your Dog On the Radio and in Vestal, NY [Uncertain Principles]

Science Blogs Physcial Sciences - 23 March, 2012 - 15:55

sidebar_relativity_cover.jpgThe quick publicity items for this weekend:

1) I will be on the Science Fantastic radio show either Saturday or Sunday, depending on when your local affiliate runs it (or when you choose to livestream it over the Internet). The interview has already been recorded, which leaves me free for:

2) I will be signing and possibly reading from the new book at the Barnes and Noble store in Vestal, NY at 2pm on Saturday. If you're fortunate enough to live in the Southern Tier, stop by and say hi.

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Categories: Education

How to Have My Dog Teach You Physics [Uncertain Principles]

Science Blogs Physcial Sciences - 22 March, 2012 - 16:52

"Hey, dude," the dog says, looking concerned. "We need to talk."

sm_talking_in_lab.jpg

"Yeah? What's up?"

"Look, it's great that you're transcribing the human puppy's stories into Twitter and all, but I'm feeling left out. I've got my own Twitter account and all, but you hardly ever type any of my tweets any more. I have to do it myself, and it's hard to be witty when you have to type with your nose."

"I'm sorry. Is there something specific you'd like to tweet about?"

"Well, yeah," she says, in a tone like I've said something stupid. "I mean, obviously, we have a new book about relativity. And look at this picture-- we're in a cool physics lab! I want to tweet about physics!"

"OK, we can do that. Anything specific you have in mind?"

"Ummmm... no. But I bet somebody else could come up with physics things for me to talk about, if you asked them..."

------

Which is how we got to here. So, here's the deal: If you're on Twitter, ask a physics question of Emmy using either her Twitter name (@queen_emmy) or the hashtag #dogphysics, and she'll answer. Ever wondered how a dog would explain general relativity? The second law of thermodynamics? Why cats land on their feet, even when you chase them off a high place really fast? Ask your question, and I'll give you her response.

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Categories: Education

This is what your Universe looks like! [Starts With A Bang]

Science Blogs Physcial Sciences - 21 March, 2012 - 22:31

"Deep into that darkness peering,
long I stood there, wondering, fearing,
doubting, dreaming dreams no mortal
ever dared to dream before." -Edgar Allen Poe When you look out into the darkness of a moonless, unpolluted night sky, you'll of course notice that it's full of stars, planets, and the occasional extended object.

MilkyWay_June8_08-1024x682.jpeg

(Image credit: Bob King at AstroBob.)

But you'll also notice that there are plenty of regions that -- other than a few stars -- don't really have very much going on. One such region, visible in the southern skies pretty much year-round, is the constellation of Sextans.

sextans.jpegsextans-t.jpeg

(Images credit: Jim Kaler.)

A region of space where there isn't very much going on -- no bright stars, no planets, no close, extended galaxies or nebulae -- is ideal for looking out, deeply, into the Universe.

You may remember, very famously, that the Hubble Space Telescope has done that a number of times, producing images such as the magnificent Hubble Ultra-Deep Field, an image which contains around 10,000 galaxies!

hudf.jpeg

(Image credit: NASA / ESA / S. Beckwith (STScI) and the HUDF team.)

And that, well, that's a lot. But is that the record?

If it was, it certainly isn't anymore! Because that region of space I showed you, above, in the constellation of Sextans? The European Southern Observatory has -- with their VISTA telescope -- created the deepest wide-field image of all-time, containing over 200,000 galaxies!

eso1213a.jpg

(Image credit: ESO/UltraVISTA team. Acknowledgement: TERAPIX/CNRS/INSU/CASU.)

The ESO has released a couple of videos, where you can see exactly where on the sky this region is, and zoom in a bit on some of these 200,000+ galaxies. In the video below, the full region of the survey -- known as UltraVISTA, of the COSMOS field -- is visible at about 0:31 into the clip.

(Video credit: ESO/A. Fujii/Digitized Sky Survey 2/UltraVISTA teamESO; music by John Dyson.)

Zooming even deeper into the field and panning around, the video below showcases some of the highlights of this survey.

(Video credit: ESO/A. Fujii/Digitized Sky Survey 2/UltraVISTA teamESO; music by John Dyson.)

Of course, they've also created an interactive, zoomable version of this survey. I've taken the liberty of creating for you a sample of what it's like to zoom in, by a factor of 4, on a given region of the original, full wide-field survey.

To remind you, here's the original image.

eso1213a.jpg

Now, let's zoom in to the upper-left quarter of this field.

eso1213a_4th.jpg

Now, let's take another quarter (lower right) of that, for 1/16th of the original image.

eso1213a_16th.jpg

And another quarter (lower right) of that, giving us just 1/64th of the original field-of-view...

eso1213a_64th.jpg

And another quarter, bringing us to 1/256th the original...

eso1213a_256th.jpg

And finally, down to the maximum resolution, just 1/1,024th of the original image!

eso1213a_1024th.jpg

Remember, as we did this, that the only remarkable thing about this patch of space is how unremarkable it was! With the exception of two or three faint stars, every dot of light in this image is a galaxy, containing hundreds of billions (or more) of stars! And by doing this to the entire image, we can determine that there are more than 200,000 galaxies in this space.

And that's what your Universe looks like! I'll be away at MidSouthCon until next week; hope you have a great one until then!

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Categories: Education

Shedding Light on Quantum Gravity: "Probing Planck-scale physics with quantum optics" [Uncertain Principles]

Science Blogs Physcial Sciences - 21 March, 2012 - 17:05

ResearchBlogging.orgIt's been a while since I did any ResearchBlogging posts, because it turns out that having an infant and a toddler really cuts into your blogging time. Who knew? I keep meaning to get back to it, though, and there was a flurry of excitement the other day about a Nature Physics paper proposing a way to search for quantum gravity not with a billion-dollar accelerator, but with a tabletop experiment. There's a write-up at Ars Technica, but that comes at it mostly from the quantum gravity side, which leaves room for a little Q&A from the quantum optics side.

Wait a minute, you said this is in Nature Physics? I don't have access to that. You're in fine company, because neither do I. Thanks to the arxiv, though, you can read a preprint for free, and that's what I'll be working from.

OK, so what's the deal with this quantum gravity stuff? Are you telling me they can make a black hole with lasers, now? No, there aren't any black holes involved, even though black holes are the canonical example of a system where you need quantum gravity to understand what's going on. Black holes are rather difficult to work with, though, so people who want to look for a quantum theory of gravity try to find other ways to see its effects.

In this case, they make use of the fact that most theories of quantum gravity involve a minimum length scale. That is, there's a minimum length below which you can't talk about distances in any sensible way.

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Categories: Education

Max Kurzweil Describes the Science Behind the Potato Chips [USA Science and Engineering Festival: The Blog]

Science Blogs Physcial Sciences - 21 March, 2012 - 16:00

By Max Kurzweil

allen kurzweil.jpgWhen we're at a baseball game or on a picnic we call 'em chips. But when we're cooking up experiments at the Chip Science Institute we maintain in our basement, or at the USA Science and Engineering Festival in Washington D.C., we call the world's most beloved munchie "research material."

For the last five years my dad and I have been using potato chips as a portal into the world of biology, chemistry, earth science, and physics. Who knew thin-sliced, deep-fried tubers could teach us about buoyancy, electrostatics, surface tension, acoustics, forensics, Bernoulli's principle, and more. When we tell you that investigating the material properties of the potato chip can be a BLAST, we mean it. (We'll be giving away a few dozen potato propulsion pipes to prove the point!) So for folks who like snacking on science high in saturated facts, you can't go wrong analyzing the material properties of chips, bags, lids, spuds, and tubes. Hope to see in D.C. -Max Kurzweil, co-inventor of Potato Chip Science (the bright blue bag of experimental swag).

You can meet Max Kurzweil and Featured Author Allen Kurzweil at the Festival Sunday, April 29th at 12:45 PM on the Family/Hands On Science Stage.

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Categories: Education

There has been a large earthquake in Mexico [Greg Laden's Blog]

Science Blogs Physcial Sciences - 20 March, 2012 - 20:46

The 7.6 7.4 magnitude earthquake struck 120 miles east of Acapulco. There are no details yet.

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UPDATE: With a bit of time passing, it is starting to look like a lot of stuff got shook-up, but there was not a lot of significant damage anywhere.

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Categories: Education

A Martian Supernova for Skywatchers Everywhere! [Starts With A Bang]

Science Blogs Physcial Sciences - 20 March, 2012 - 19:20

"When I had satisfied myself that no star of that kind had ever shone before, I was led into such perplexity by the unbelievability of the thing that I began to doubt the faith of my own eyes." -Tycho Brahe When stars reach the end of their lives, there are many possible fates that they can have. Among the most spectacular, however, are stars that end their lives by going supernova, where a single star can outshine even an entire galaxy for a brief moment in time.

sn2006gy_3panel.jpeg

(Image credit: SN 2006gy, X-ray by NASA / CXC, Nathan Smith, Weidong Li et al., IR by PAIRITEL / Lick / U.C. Berkeley / J.Bloom, and C.Hansen.)

Last year, we experienced the closest supernova in a generation, when a star died a spectacular death in a relatively nearby galaxy.

Although it isn't nearly as spectacular as what we'd get to see if we experienced another supernova within our own galaxy, a phenomenon not experienced on Earth since 1604!

sn1604wiki.jpeg

(Image credit: Stellarium.)

When they occur within our own galaxy, supernovae are so bright that they outshine all the other stars, all the planets, and can often even be seen during the day. They're very rare, though, occurring less than once per century, on average, in our own galaxy.

But there are other galaxies that have better luck than we do.

hs-2007-15-a-xlarge_web.jpeg

(Image credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA).)

Many galaxies, unlike our own, are actively forming large quantities of stars! In many spiral galaxies, like NGC 1672, above, pink regions can line the arms of galaxies, surefire evidence of recent, intense star formation. Recent mergers, including the gobbling up of small, satellite galaxies, as well as simply the density waves of spiral arms can often trigger this type of star formation all on their own.

But when galaxies gravitationally interact with one another -- even when separated by millions of light years -- they can intensify this ongoing star formation.

With this in mind, let me introduce you to one of the nearer galaxies in our night sky: Messier 95 (M95).

M95_281202.jpeg

(Image credit: Paul and Liz Downing.)

Messier 95 is a spiral galaxy, with strong inner arms and faint outer arms, located 38 million light years away. It's also very close to Messier 96, and Messier 105; together, with a few other galaxies, they form a group! The image below, created by me with Stellarium, shows the entire group, all contained within just a single degree in the night sky.

Mars_M95_SN.jpg

You'll also notice, in the upper right of the image, lies the planet Mars.

Shining brightly in the night sky, Mars, in many locations, is the brightest object visible in the sky during much of the night. It doesn't look like it, in the image above, because I've artificially reduced its brightness by a factor of many thousands. Normally, astronomical observers look for the following traits when they go to take their observations:

  • clear, dark skies,
  • far away from any sources of light pollution,
  • a moonless night, and for the most hardcore,
  • high altitudes (to limit atmospheric interference).
But if you want to take a look at Messier 95, you'll want to make sure to leave Mars out of your field of view, otherwise you'll never see the galaxy! Why's that?

M95-wide1-1024x822.jpeg

(Image credit: Jim Misti / Map created with Stellarium, retrieved from Astro Bob.)

Messier 95 is located less than half-a-degree away from Mars in the night sky, but appears to be about 100,000 times less bright than the red planet right now. On the magnitude scale (smaller is brighter), M95 is magnitude 9.7, while Mars is of magnitude negative one.

But you'll want to see Messier 95 now, because in a region of that galaxy that contained absolutely nothing, a very bright object suddenly appeared just four days ago, and is increasing in brightness; it's got to be a supernova! Zooming in on the earlier image of M95, I want to show you exactly where you should look if you want to see it; anyone with an 8" telescope or bigger (and the proper magnification -- 100x for an 8") should be able to find it! (But no smaller than a 6" under the best of circumstances for now; you'll waste your time looking for it.)

m95_paulandliz_add.jpg

(Image credit: Paul and Liz Downing, marked by me.)

At this point, we haven't officially determined whether it's a type Ia supernova (formed by an exploding ancient white dwarf) or a type II supernova (formed from a very massive, young star that's finished burning its nuclear fuel), but look at the location: it's right on one of the outer spiral arms! That's one of the key places where young, massive stars form, and so just by looking at that, I can tell you that it's almost definitely a type II supernova.

Want to know what it looks like through a telescope? Take a look, below.

New_SN_and_Mars.jpg

(Image credit: Nik Szymanek.)

As you can see, marked by the lines, there's a fairly distinct object that looks like a star within our own galaxy. But that's not a Milky Way star, a few hundred or a few thousand light years away, but a supernova in Messier 95, located 38 million light years distant! Over the coming weeks, the supernova will continue to brighten, and will be more clearly visible and more easily seen. But one thing that won't change all that much is that ruinous light pollution, captured by Nik Szymanek, above.

Know what's causing it? That's Mars!

Mars_SN_deepsky.jpg

(Image credit: Nik Szymanek from Deep Sky Videos / Brady Haran.)

If you want to see more, and you can't wait for the information to unfold, there are two things I recommend you check out. First, David Bishop has some early photos on his site, where you can find before-and-after photos of Messier 95.

And if you need more right now, Deep Sky Videos has put together a wonderful presentation -- released just yesterday -- on this supernova so far.

So if you can find Mars, and you have a good enough telescope and good enough skies, you can be among the first to see the latest supernova in our night sky!

Update: The supernova has been confirmed! It's a Type IIp supernova, and its name is SN 2012aw! It will brighten, and continue to be visible probably into June, when Mars will have (finally) moved a considerable distance away. Keep watching!

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Categories: Education

The Quantum Universe by Brian Cox and Jeff Forshaw [Uncertain Principles]

Science Blogs Physcial Sciences - 20 March, 2012 - 15:59

So, this is the new book from the authors of Why Does E=mc2?, covering quantum mechanics in a roughly similar manner. This book, or, rather, Brian Cox talking about some material from this book, created a bit of controversy recently, as previously discussed. But other than that, Mrs. Lincoln, how did you like the play?

The big hook here is that they set out to discuss quantum mechanics for a popular audience using a Feynman-type picture from the very beginning. This is an intriguing idea, and sort of appealing in the same basic way that Sakurai's famous graduate text in quantum mechanics and Townsend's undergraduate version appealing. Those books are interesting because they come at the subject from a different angle, formulating everything first in terms of spin-1/2 particles, rather than wave mechanics. This makes certain types of problems much easier to deal with, and lets students see the subject in a very different light.

So, the general idea of a book on quantum physics that starts with Feynman's path integral formulation of the theory-- other than, you know, Feynman's own book on QED-- is an interesting idea. The Feynman approach is the starting point for a lot of modern approaches to the theory, and looks very different than the Schrödinger wave mechanics most popular treatments (my own included) take. I got some useful stuff out of their book on relativity, so I was hoping for some useful insights from this one.

Like its predecessor, though, I want to like this book more than I do.

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Categories: Education

How to Teach Relativity to Your Dog Publicity Update [Uncertain Principles]

Science Blogs Physcial Sciences - 20 March, 2012 - 14:51

A couple of cool items in the promotion of How to Teach Relativity to Your Dog:

-- A little while back, I spoke to Alan Boyle, who writes the Cosmic Log blog for MSNBC, who posted a very nice story about the book last night. Mainstream media, baby!

It also uses this very cool picture of Emmy and me in my lab:

emmy_in_lab.jpg

(Many thanks to Matt Milless for taking that and a bunch of others.)

-- This weekend (either Saturday or Sunday, depending on where you are), I'll be on the Science Fantastic radio show, talking about relativity with Michio Kaku. There's a lsit of stations that carry it linked from that page, or you can listen online (this site purports to let you stream it, but I haven't tried yet.

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Categories: Education

Neutrinos and the Search for Extraterrestrial Intelligence [Starts With A Bang]

Science Blogs Physcial Sciences - 20 March, 2012 - 02:35

"To use Newton's words, our efforts up till this moment have but turned over a pebble or shell here and there on the beach, with only a forlorn hope that under one of them was the gem we were seeking. Now we have the sieve, the minds, the hands, the time, and, particularly, the dedication to find those gems--no matter in which favorite hiding place the children of distant worlds have placed them."
-Frank Drake and Dava Sobel Looking up at the canopy of stars in the night sky, and realizing that each point of light is a star system not so unlike our own, one can't help but wonder about those extraterrestrial worlds that we know exist around a tremendous fraction of them.

W3.jpeg

(Image credit: Tom's Eye on the Sky.)

With hundreds of billions of stars and (possibly) upwards of a trillion planets, it's been known for a very long time that there's a definite, real chance that other intelligent life exists right now in our own galaxy.

For decades, we've broadcast radio messages out into space, and built giant arrays of radio telescopes, searching for those same types of signals originating from other sources in the night sky.

vla_soorr.jpeg

(Image credit: VLA in Socorro, New Mexico, retrieved from here.)

Of course, this is a tremendously ambitious task. Even a very intense radio signal will lose its power the farther away from it you are. The problem, of course, is that each time you double the distance away from a radio transmitter, you pick up only one-quarter of the intensity you would have received at a closer distance.

radio%20transmitter.gif

(Image credit: Arthur's Clip Art.)

Even special setups that collimate the beam -- assuming, for example, that an alien species had the idea to point their beam directly at us -- still suffer from this. Even the best setups for beam collimation of light still wind up having the signal spread out over a substantial angle, and still suffers from the problem that the farther away you are, the less intensity you receive squared: a radio transmitter ten times as far away needs to be a hundred times as powerful for you to pick up the signal.

StdFresCollimator.gif

(Image credit: Chris Long.)

It's difficult to imagine that a civilization-generated signal located thousands of light-years away, across the galaxy, would be able to outshine the cosmos by time it reached us.

But we do have one sterling example of a beam we can collimate to an outstanding precision: beams of extremely high-energy particles!

0911188_01-A4-at-144-dpi.jpeg

(Image credit: Maximilien Brice, 2009.)

A pulse of high-energy particles, such as the kinds we create at the Large Hadron Collider, above, achieves speeds around 99.9999% the speed of light, more closely collimated than even the beam from a laser. Now, we sometimes receive high-energy particles -- originating from space -- here on Earth. When we do, how do we identify them?

cosmic_ray_spallation_big.jpeg

(Image credit: Randy Russell using a photo via UCAR / Nicole Gordon.)

They strike the Earth's upper atmosphere, producing a shower of particles. Neutrinos and muons make it to the ground, where -- if we're lucky and prepared -- we can identify them. Launched from Earth, however, the charged particles would certainly hit the atmosphere on the way out. And since muons are unstable, by time they arrived at their destination, the only recognizable signal would be the neutrinos!

In other words, if we wanted to send a signal to an alien world, alerting them to our presence, our best bet would be to send them collimated, patterned pulses of neutrinos!

cs02p06graphic1l.gif

(Image credit: Jerry Ehman, republished from Smithsonian Magazine.)

What's remarkable about this -- even though it wasn't the experiment's intention -- is that we just demonstrated the ability to detect exactly this type of signal!

How's that?

pictures.jpeg

(Image credit: MINERvA team / University of Rochester.)

Last week, scientists announced -- for the first time -- that they sent a neutrino signal through the solid rock of the Earth, in binary morse code, and received it at a neutrino detector over a kilometer away!

completed-TP3-big.jpeg

(Image credit: MINERvA Collaboration.)

Despite the fact that only one out of every ten billion neutrinos can be detected in an apparatus like the MINERvA detector, above, and that the effective transmission rate was only one bit every ten seconds, by repeating the message many times, the detector was able to build up the binary pattern of zeroes and ones, eventually decoding the binary message!

minervadetector.png

(Image credit: D.D. Stancil et al.)

What was the message? Why, the name of the particle itself: N-E-U-T-R-I-N-O.

If someone, thousands of light years away, is sending a repeating neutrino signal towards us, we've just demonstrated the capability of detecting and identifying exactly that type of communication.

The signals of intelligent life could already be there. We just need to listen in the right way, and neutrinos might be the answer!

(Also, a big thanks to Randall for the elegant new blog banner; hope you like it!)

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Categories: Education

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