Science

Skin Deep

I’m always impressed with the ingenuity scientists display when coming up with names for natural phenomena.  When introduced to the public, abstract mathematical concepts are presented with extremely evocative, almost emotional names that manage to cut to the heart of the math: black hole, big bang, the special theory of relativity.

Okay, so not always.  But enough of the time that it’s impressive — a way to directly connect science to intuition.  One of my favorite examples is a phenomena in electromagnetism called the skin effect, which describes how alternating current is carried in wires.  The skin effect is particularly interesting to me because it’s also a pretty direct analogy for a lot of the interactions I have with casual acquaintances.  I don’t think it’s often that the fields of social science and, well, science science intersect so perfectly — not only on a nomenclature and imagery level, but in the behaviors they describe.  I’ll start, as always, with physics.

The skin effect occurs all around us.  (It is notably distinct from the article in this month’s Cosmo with the same title.)  When electric wires carry alternating current — i.e. the stuff that comes out of the wall and/or one half of a legendary Australian rock band — most of the current never actually penetrates all the way through to the center of the wire, instead skirting along on the surface, creating a kind of electric sheath or skin along the wire.  This is a big break from the orthodoxy of how electromagnetism is usually taught in school, where it’s a common analogy to think of electricity racing along wires like water flowing though pipes.  While true for direct current (DC), this breaks down with AC — you’ll never see a water pipe with a hollow center and water rushing along the edges.

The difference mostly comes from the key distinction between AC and DC current, and is what makes AC so devilish to work with without an assload of math behind it.  Alternating current is called “alternating” because it switches back and forth, constantly, from positive voltages to negative voltages.  It rolls in and out of your wall like the tides at the beach, pushing electrons in and then dragging them back out to sea.  This inexorable changing of the electronic tides creates magnetic fields that similarly expand and collapse as the voltage changes, but these magnetic fields are always strongest in the center of the wire.  If you want to go back to the water analogy, magnetism here acts like a rock in the stream, pushing the flow of electrons around it and forcing the electricity to hug the banks of the stream, so that the vast majority of the current is carried along the outer skin of the wire.

I’ve always thought that the beauty of electricity and magnetism are their complexity: changing currents cause changing magnetic fields, changing magnetic fields cause changing currents, and the process constantly ebbs and flows in harmony, a symphony of the invisible as fields burst into life then dissipate into void, over and over and over again.

But that has nothing to do with friendship — and, in fact, I think if you start spouting that stuff at parties you may find yourself with a lot fewer friends by the end of the night.  So back to the main point here: the AC current carried in a wire — whether a transmission cable along the side of the road or the extension cord in your garage — only penetrates a fraction of the way into the wire.  This is called skin depth, designated δ.  Formally, skin depth is the depth into a conductor where the current carried falls to 1/e, or about 37%, of its value at the surface.  For AC frequencies in the realm of everyday experience — think the 60Hz that goes into your iPhone charger — skin depth is a function only of the material the wire is made from and the frequency of the current:

skin depth

Here ρ is the resistivity of the wire, f is the frequency of the current flowing through it, and the μs are something called magnetic permeability, which is a measure of how susceptible a material is to magnetic fields.  Something like iron, which can be made into a magnet, has a very high permeability; the permeability for wood or glass is very low.

For a current coming out of the wall and into copper wire, the skin depth is:

Screen Shot 2016-03-13 at 3.01.15 PM

For your phone charger, this means nothing — the wire is way smaller than 17mm in diameter.  But imagine the transmission lines used to send electricity from the power plant to your house: those cables that hang from wooden poles along the side of the road are much bigger, and that means when it comes to electricity they’re essentially hollow.  All of the power is running along the skin, never reaching the heart of the cable.

As the frequency of the current, f, gets bigger and bigger, the skin depth shrinks — as the electricity switches back and forth from positive to negative voltages faster and faster, the current penetrates into the wire less and less.  AC current switching at 150,000Hz penetrates into copper wire just 170 microns, or about the diameter of a human hair.  It will never see the copper’s core.

This is where my social circle enters the equation.  I have — and I assume you have, too — a lot of what I call skin effect friends.  (Though admittedly, I’m probably the only one of us who calls them that.)  These are the people that I’ve met casually and who circle the nucleus of my close friends in fast but erratic orbits.  They show up across the room at parties; I see them walking down the street in San Francisco.  Maybe I remember their names, maybe I don’t.  I usually don’t have their phone numbers or know their email addresses.  But every time we see each other, these skin effect friends and me, we say hello, because the world is a big and scary and sometimes lonely place, and finding a familiar face in an unexpected setting is a beautiful thing.

Yet when I talk to these people, I never actually have a conversation with them.  We only ever hit the topics that are skin-deep: how are you, where’re you living, how’s work these days.  And it seems that the more frequently I see them, the shallower the topics become, just like current skirting around the outside of a wire.  We never get to the heart of anything.

This isn’t a critique or a complaint — I can’t be best friends with everyone, and I’m misanthropic enough to not want to try.  I enjoy having a wide circle of acquaintances, and I enjoy these skin-deep conversations because they show me the surface of worlds I don’t inhabit.  I wish I could dive into those worlds, wish I could be deeply connected to everyone I’ve ever met, but just like a wire, there’s only so much current I can carry before I catch on fire / have a total psychotic breakdown.  So if you’re reading this and thinking to yourself wait a minute that bastard is talking about me, it’s not a bad thing.  Next time we run into each other, let’s grab a beer.  We’ll talk about sports.

And even though I like all these skin effect friends, they also make me acknowledge that those friends I have where our conversations do penetrate — those friends where, even if we don’t see each other very frequently, we can pick up right where we left off, or those friends who I feel like I really connect with — are something remarkable, almost physics-defying.  It’s DC friendship.

There’s a lot of discussion about a possible unified field theory in physics, but I’m happy stopping at a unified theory of physics and friendship.  Einstein, eat your heart out.

Advertisements

Compressing

There’s something magical, in the Arthur C. Clarke sense of the word, about compression algorithms — take something that’s too big for a box, and squeeze it into that box regardless.

But, of course, not everything can simply be squeezed smaller.  Some coworkers and I were talking this week about needing to extract the information in an image from a range of wavelengths about a nanometer wide, and how that wouldn’t really just work by filtering an optical image repeatedly (the range of light visible to humans is about 300 nm).  Encoding enough information in the original image so that filtering it down is actually useful — and so that the original image doesn’t take up a server farm worth of digital storage — would probably take a huge amount of compression, ratios of 1000 or 10,000 to 1.  To put that in a little bit of perspective, an uncompressed song file would be maybe 50 MB, while an .mp3 of the same song could be as little as 3.5 MB — a 14:1 ratio.  So thousands-to-one is a lot.

This is when one of the PhDs who started this conversation compared this task to trying to represent The Iliad as a limerick.

Well, challenge accepted.

It varies by translation, but The Iliad is about 150,000 words long.  A limerick, in its classic form, is two lines of two anapests (those are the ones that go “da-da-DUM”) sandwiched between three lines of three anapests for a total of 39 syllables.  It was surprisingly hard to find a good answer for the average number of syllables in an English word, but 1.3 seems to be a good guess.  (If you’re interested, you can look at this paper or use this online calculator, which I dropped some public domain works into: The Time Machine, Huckleberry Finn, and The Picture of Dorian Gray.  You can also look at this Wikipedia list, which is mostly unrelated but fantastic.)  That means 39 syllables is approximately 30 words, and turning Homer’s epic poem into a form more widely know for New Englander autofellatio jokes is about a 5000:1 compression — an impressively accurate off-the-cuff analogy for what we were talking about.

Here’s my shot at The Iliad in limerick form:

With abduction of Helen the source,
Menelaus responded with force
So the Greeks sailed for Troy
Set to burn and destroy
But just eked out a win with a horse

And why stop there?

How about the Old Testament in haiku, or taking 600,000 words down to 17 syllables (13 words-ish)?

Birth of light, then man
Wandered until given rules:
Be nice, no bacon

I’m open to suggestions for future compression here.  Will update this post as I have more ideas.

NASAing of Teeth

Buckle up, boys and girls, because it’s three weeks into 2015 and I am already fucking livid.

I know that I’ve gone off before on science in politics — or, agonizingly predictably, lack thereof — but I have to do it one more time.  I have to, really, because we just put Ted Cruz in charge of NASA.

Okay, so not exactly in charge.  To be precise, the midterm election turnover in the Senate means Cruz now chairs the Subcommittee on Space, Science, and Competitiveness (Oxford comma officially omitted, but added here out of compunction), which oversees NASA, the NIST, the NSF, the OSTP, and apparently about 30% of all acronyms.

Why is this bad news?  By all accounts, Ted Cruz is a smart dude.  He was his high school valedictorian, went to Princeton and Harvard Law.  He should be the best of the best of what America can offer up, the upper crust of elite erudition that decides to apply itself to solving the country’s problems and propelling it into the next generation stronger, smarter, better than it was before.

Instead, Ted Cruz says shit like this:

My view of climate science is the same as that of many climate scientists.  We need a much better understanding of the climate before making policy choices that would impose substantial economic costs on our Nation.

Hi, Ted?  I have NASA on the line here.  You know, that science agency you’re about to be responsible for.  Lots of glasses and calculators and pocket protectors and weird-looking mohawks.  Anyway, they just wanted to make sure you’re aware that NINETY-FUCKING-SEVEN PERCENT OF ALL CLIMATE SCIENTISTS believe they have a handle on what’s going on, and that we need to do something about it.

Oh, but “[the] data are not supporting what the advocates are arguing”?  For a guy who knows how to use “data” correctly in a sentence, that’s not a very smart thing to say.  Here’s this thing we scientists like to call a “graph”:

I JUST.  CAN’T.  EVEN.

So the truculent Ted Cruz, who is either so brilliant he knows something the rest of us don’t or so willfully ignorant he refuses to acknowledge something the rest of us see as self-evident, is going to watch over our nation’s science policy.  I feel about as comfortable with that as I do leaving my future children at Mikey Jackson’s Daycare Center and Used Needle Emporium.

I realize that it’s maybe unfair of me to extend Cruz’s views on climate change to the rest of his scientific thinking.  But I have to.  I have to, really, because you don’t trust heart surgery to someone who believes in the healing power of leeching.  You don’t trust bridge building to someone who doesn’t know a truss from a trull.  You don’t trust polymer science to someone who believes in alchemy.

So why — why — are we trusting the future of scientific research to someone who doesn’t believe in scientific research about the future?

And I know these are criticisms that have been leveled against Cruz before; I’m not unique in my fulmination.  But I have to fulminate.  I have to, really, because 2014 was, unsurprisingly, the hottest year we’ve ever experienced — and that’s not a reference to any Kardashianic attempts to break the internet.  Just our species’ repeated attempts to break the planet.

Yet the people with guiding hands in our scientific policies choose to ignore that.  I’m not just talking about Cruz, though he makes an exceptional example.  His colleague Marco Rubio, who once said of climate change “I don’t think there’s the scientific evidence to justify it”, will be taking over leadership of the Senate Subcommittee on Oceans, Atmosphere, Fisheries, and the Coast Guard.

OCEANS.

ATMOSPHERE.

FISHERIES.

AND THE GODDAMN COAST GUARD.

Rubio, who refuses to acknowledge that climate change, anthropogenic or not, could have catastrophic effects on the oceans and atmosphere (ironically threatening the Rubio’s hand-battered fish taco especial) is now presiding over the agencies responsible for the oceans and atmosphere.  How is this supposed to give me faith in the government’s ability to safeguard our country’s natural resources?  Our planet’s?

I can only point out the absurdity of the whole situation — no, I have to point out the absurdity of the whole situation.  I have to.  Really.  Because our country’s scientists deserve better than overseers who deny basic science.

The United States of America was arguably in the vanguard of every major technical innovation of the twentieth century.  We built, we flew, we coded.  We cracked the atom, conquered the moon, colonized the internet.  And we did these things with the help of our government, with the help of federal research money and the aid of the United States Congress.

What path do we have forward in the twenty-first century if scientific progress is held hostage by non-believers?

The Eagle Has Landed

This weekend marked the 45th anniversary of the Apollo 11 moon landing, the first mission that successfully landed human beings on a thing that wasn’t the thing on which every human being ever in the entire history of humanity has lived.

That we as a species pulled this off is still staggering to me.

We put three living humans into a small metal tube perched on six million pounds of concentrated liquid explosion, shot them straight up into the air until they reached a point where they are so high up there is literally no more air, then guided the metal tube to a piece of space rock hurtling through the void almost 240,000 miles away from the Kennedy Space Center, and did it with less computing power than I carry around in my pocket today.

(I use that computing power, by the way, to look at cat videos. To reiterate, NASA used it to send three men — three normal, terrestrial people who cannot fly and who must breath air — to THE GODDAMN MOON.)

The sheer audacity of the US space program’s goal — to send living, breathing people to the moon and then bring them back still living and breathing — is incredible. Beyond the technical challenges this had to pose to 1960s-era scientists and engineers who were still marveling at the hand calculator, beyond the funding that had to be found by politicians who had chilly wars to fight, beyond the undoubtedly bowel-loosening terror that had to be faced by the men in the Apollo capsule as they careened wildly through the firmament towards a tiny chunk of rock floating in an endless sea of nothing, one simple fact remains: the moon is really, really, really far away.

A case study: Apollo 11 launched from the Kennedy Space Center in Orlando. The closest Taco Bell to Kennedy is 13.2 miles away. The astronauts that left Kennedy to go to the moon could have traveled round-trip to that Taco Bell more than nine thousand times and not covered the same amount of distance. That’s beefy five-layer burritos for breakfast, lunch, and dinner for more than eight fucking years.

Or they could have driven from the launch site to Washington, D.C. and back 140 times, a trip that would take 146 days of non-stop driving. Or to San Francisco and back 50 times. To Fairbanks, Alaska and back 25 times. They could have gotten in a plane and circumnavigated the globe almost ten times (no great circles here — I’m talking circumference) before reaching the moon.

My point being the moon is really, really, REALLY far away, guys. It’s cold and it’s alien and it’s distant and we’ve been there. Forty-five years later, the moon landing remains one of the most impressive things accomplished by mankind. It is, of course, a testament to what we can do when we put our minds to it, work together, follow through on some third sports movie cliché, and decide there’s no way those goddamn red-loving commie bastards are getting there first.

In thinking about how to close this post, I was tempted to point to the moon landing as proof that government-sponsored science works, that it’s important, that’s it needs to continue. I believe that’s all true, but I don’t want to use this anniversary to harp on that message too much. Because when it comes down to it, forty-five years ago mankind — essentially a troop of slightly-evolved and overly-opinionated monkeys — shoved three of its own in a can, blasted them into outer space, and took that first small step into the giant universe beyond our world.

And that’s just really, really cool.

Cosmopolitan

I watched the first episode of Fox’s new edition of “Cosmos” this week.  I was surprised, though maybe I shouldn’t have been — surprised to see such an unapologetic paean to science on primetime American television.  It captured beautifully the power and wonder of the scientific method, of humanity’s quest to explain its place in the universe.  It waxed elegantly about data-driven decision making and hypothesis testing, about critical reasoning and status-quo questioning.  And having Neil deGrasse Tyson at the helm didn’t hurt.

I’m always struck by two thoughts, always in the same order, whenever something like “Cosmos” gets me thinking about the universe.  The first is how incalculably small and insignificant I am — how incalculably small and insignificant we all are, here on this warm ball of rock in the cold void of space.  There are galaxies beyond galaxies pressing on the feeble curtain of Earth’s atmosphere, infinities of nothing on our doorstep that swallow the planets and the moons and the stars.  I will never see the Virgo supercluster, let alone the Milky Way.  I’ll see Mars in images and X-ray diffraction patterns.  I won’t even see all of Earth.  The billions of planets in our corner of the universe are still too few, too far between, too spread and scattered through a field of black interstellar velvet, impossible to traverse.  What can anything I hope to do matter, when something like only four percent of the universe is matter?  If I was to conquer the Earth and carve my likeness in every mountain and write my name in every desert and blaze my way into every book and song and poem mankind could concoct — it would still be fleeting and immeasurable when compared to the humming of the planets and the singing of the stars.  There’s just so much space out in space, a kind of cold, insufferable beauty that makes me marvel at the grandness of creation and shrink into my own inconsequence at the same time.  I don’t know if I’ve managed to capture in words here the enormity — the primordiality — of this feeling.  I feel like I’m both adrift and confined, floating unmoored and yet suffocated by the sea.  I feel as if the sheer amounts of nothing surrounding the earth are bearing down on me like a weight, impossibly heavy, and crushing me with the realization that I will die with the mysteries of the universe unknown and gnawing at my soul.  That I will die, and the universe will continue.  That I will die, and in the entirety of my life I will have experienced the smallest fraction of a fraction of what the cosmos have to offer — and I could live a thousand lifetimes more, on a thousand different planets, around a thousand different stars, and the same thought would still be true.

Then, slowly, the second thought boils up from deep within the first.  It starts, usually, by thinking about life instead of death.  About how there must be life out there — somewhere — and how statistics can’t be so wrong that more than a billion billion planets wouldn’t manage to pull off what Earth has done.  I think this, but the thought is usually quashed by Fermi’s paradox, which brings me back out into the unquenchable abyss, into that endless maw of loneliness, spiraling along the spirals of our galaxy until I’ve spun all the way back out into nothing.  And it is here, always here, right at the event horizon before I fall alone into that endless astral gulf, when the second thought blossoms into being:

We live in an infinity of nothings, and yet a universe of everything.

Everything is out there, waiting for us to discover it.  That’s why talking about the scientific method is so important: the joy of discovery.  It’s a primal emotion that has driven mankind onto two legs, across oceans, up to the moon.  We’re not crushed by the realization that there’s too much in the cosmos to comprehend.  We’re driven to comprehend as much of it as possible while we’re around.  “Cosmos” (and, really, anything in the same vein) hit on that joy of discovery in me, and hopefully in millions of other children and young adults throughout the country and the world.  The world needs — and deserves — more thinkers and fewer dogmatists.

But the thought goes deeper than that.  Tyson used a line in that first episode of “Cosmos” that I really liked: that we are made of “star stuff”.  Our bodies’ iron, carbon, calcium — our blood, our flesh, our bones — were formed, unfathomable ages ago, in the heart of a star.  We have the heavens within us, written not in our DNA but in our very molecules and atoms, and we carry this celestial signature about every extraordinary (and every mundane) minute of our lives.  We are the universe.  The universe is us.

If you’ll allow me a tangent that will eventually reconnect with this thought, let me to take you on a journey through time and space, albeit a bit shorter in both dimensions than Tyson’s.  The year is 2007, the place is William S. Hart High School, and I am reading (or am being forced to read, who knows) James Joyce’s A Portrait of the Artist as a Young Man.  I wish I could tell you I remembered what the book was about at its core, but I really only remember it in slivers and images.  One of those slivers is from the very end of the book, a diary entry where the main character (Stephen Dedalus, the titular Artist as a Young Man) talks about his drive to be great writer/poet/artist/whatever it’s been awhile since I read this.  I apologize for quoting James Joyce for what I promise is the first, last, and only time in this blog:

I go to encounter for the millionth time the reality of experience and to forge in the smithy of my soul the uncreated conscience of my race.

I read this as Dedalus’ desire to bring his own individual perspective into the greater fabric of humanity’s story — how to be great, the artist must be able to turn his or her individual perspective into something universal and beyond oneself, something that speaks to what it means to be human, not what it means to be Stephen Dedalus… though you can’t lose the Stephen Dedalus in the process.

“Cosmos” and Tyson, an innovator (Daedalus?) in his own right, are saying something similar: that we are forged in the smithy of the stars, and this is the conscience of our race.  We are a part of the universe, and it is our nature to question and explore it, but only through our own minds and thoughts and deeds does this cold sea of galactic whorls and stellar eddies have a meaning, a warmth, a light, and a life.  The universe is grand and impressive and will outlast us all, and our goal as a species should be to understand the universe as a whole, not just ourselves.  But all of that tremendous amount of nothing is just that — nothing — without our everything within it.

So keep learning, keep thinking, keep questioning.  It illuminates the darkness, one neuron — one nebula — at a time.

die Sonne

An observation, which comes from a vacation I just took to Germany:

When you happen to find yourself on a train traveling from Munich, Germany to Salzburg, Austria, you have a lot of idyllic landscape to inhale.  But the stunning thing is that as you travel from one perfectly bucolic farm to the next, each rustically charming farmhouse (German: Farmhaus) you pass has one thing in common with its predecessors: a solar panel array on the most south-facing part of the roof.

Germany is a paragon of renewable power, to say the least.  It’s amazing what the right tax credits and incentives can do.  But the kicker lies in these two maps.

Pvgis_Europe-solar_opt_publication

NREL_USA_PV_map_hi-res_2008

These are equivalent maps — both show the total incident solar energy on a square meter solar panel tilted optimally towards the sun — but unfortunately, the colors don’t quite match up.  The map of Europe is in kWh/m²/year and the U.S. is in kWh/m²/day (hey, but at least it’s not hp/ft²/day, right?).  Multiplying the U.S.’s scale by 365.25 means the darkest red should be about 2447 kWh/m²/year — more than the darkest red of the Europe map.  The part of Germany I was traveling through on train is pretty solidly mindaro-colored, equivalent to about 1350 kWh/m²/year.  That works out to 3.70 kWh/m²/day, or a nice shade of emerald.

You know, emerald.  The same color as SEATTLE.

Pictured: our solar-powered future.

Atom and Evening

Ramble starting: Like probably every poem I write (there are not many of these, and even fewer good passable ones), this started out as some sort of melancholic, nostalgic reminiscence about an ex.  It is, um, no longer about that.  Which is good.  I think the title should probably be “Trinity” but the “Atom and Evening” pun was too good so I had to keep it somewhere.  Ramble over.

\ \ \ Trinity \ \ \

In the morning the atoms all sparkled and flared
A new sun in the desert, a garden of glass
When the dust of the ground formed a cloud in the air.

With a crash heard for miles, the soil was bared
And Earth knew it was nude but knew not what had passed
In the morning the atoms all sparkled and flared.

Then the heat and the light—they swelled up like a prayer,
Conflagrations to preach supercritical mass
When the dust of the ground formed a cloud in the air.

Congregations were watching, as close as they dared
For orations of fire and moral morass
In the morning the atoms all sparkled and flared.

With the sermon uncertain, men gave to their heirs
Broken bonds, a charred sky, and a bright ghostly blast
When the dust of the ground formed a cloud in the air.

The horns heralded progress, a new age declared—
While by evening the future already was past,
In the morning the atoms all sparkled and flared
When the dust of the ground formed a cloud in the air.