## Physics lessons using simple homemade marble tracks

Bruce Yeany teaches physical science to 8th graders in Annville, PA and he is very enthusiastic about it. On his popular Homemade Science YouTube channel, Yeany highlights all sorts of physics experiments and demonstrations without using any special equipment. In one of his latest videos, he shares a bunch of marble tracks that he’s built to demonstrate motion and momentum.

The “identical track race” starting at 1:43 might blow your noodle a little bit unless you’re familiar with Galileo’s pendulum research. (via digg)

## How to make an Extremely Large Telescope

The Giant Magellan Telescope, currently under construction at the University of Arizona’s Mirror Lab, will be one of the first of a new class of telescopes called Extremely Large Telescopes. The process involved in fashioning the telescope’s seven massive mirrors is fascinating. This is one of those articles littered with mind-boggling statements at every turn. Such as:

“We want the telescope to be limited by fundamental physics — the wavelength of light and the diameter of the mirror — not the irregularities on the mirror’s surface,” says optical scientist Buddy Martin, who oversees the lab’s grinding and polishing operations. By “irregularities,” he’s talking about defects bigger than 20 nanometers — about the size of a small virus. But when the mirror comes out of the mold, its imperfections can measure a millimeter or more.

Precision of 20 nanometers on something more than 27 feet in diameter and weighing 17 tons? That’s almost unbelievable. In this video, Dr. Wendy Freedman, former chair of the board of directors for the GMT project, puts it this way:

The surface of this mirror is so smooth that if we took this 27-foot mirror and then spread it out, from coast-to-coast in the United States, east to west coast, the height of the tallest mountain on that mirror would be about 1/2 an inch. That’s how smooth this mirror is.

You need that level of smoothness if you’re going to achieve better vision than the Hubble:

With a resolving power 10 times that of the Hubble Space Telescope, the GMT is designed to capture and focus photons emanating from galaxies and black holes at the fringes of the universe, study the formation of stars and the worlds that orbit them, and search for traces of life in the atmospheres of habitable-zone planets.

The telescope has a price tag of \$1 billion and should be operational within the the next five years in Chile.

## A scientific simulation of Seveneves’ Moon disaster

In the first line of Seveneves, Neal Stephenson lays out the event that the entire book’s action revolves around:

The moon blew up without warning and for no apparent reason.

Mild spoilers, but fairly quickly, scientists in the book figure out that this is a very bad thing that will cause humanity to become extinct unless drastic action is taken.

In the novel, one day the moon breaks up into 7 roughly equal-sized pieces. These pieces continue peacefully orbiting the Earth for a while, and eventually two pieces collide. This collision causes a piece to fragment, making future collisions more likely. The process repeats, at what Stephenson says is an exponential rate, until the Earth is under near-constant bombardment from meteorites, wiping out (nearly) all life on Earth.

Jason Cole wondered how plausible that scenario is and created a simulation to model it. Turns out Stephenson had his figures right.

## If you blow air through sand, it behaves like a liquid

If you take a bin full of sand and blow air up through the bottom of it, the sand behaves like a liquid. The bubbles were freaky enough when I watched this for the first time, but when the guy reached in to submerge the ball and it buoyantly popped right to the surface, my brain broke a little bit. This video from The Royal Institution explains what’s going on:

Note that this is a different effect than non-Newtonian liquids (which are also very cool).

Update: Mark Rober made a hot tub-sized fluidized air bed:

## Black holes could delete the Universe

In their latest video, Kurzgesagt takes a look at black holes, specifically how they deal with information. According to the currently accepted theories, one of the fundamental laws of the Universe is that information can never be lost, but black holes destroy information. This is the information paradox…so one or both of our theories must be wrong.

The paradox arose after Hawking showed, in 1974-1975, that black holes surrounded by quantum fields actually will radiate particles (“Hawking radiation”) and shrink in size (Figure 4), eventually evaporating completely. Compare with Figure 2, where the information about the two shells gets stuck inside the black hole. In Figure 4, the black hole is gone. Where did the information go? If it disappeared along with the black hole, that violates quantum theory.

Maybe the information came back out with the Hawking radiation? The problem is that the information in the black hole can’t get out. So the only way it can be in the Hawking radiation (naively) is if what is inside is copied. Having two copies of the information, one inside, one outside, also violates quantum theory.

So maybe black holes holographically encode their information on the surface?

## How to predict total solar eclipses

The Exploratorium in San Francisco has produced a great explainer video about the science of predicting total solar eclipses. Each eclipse belongs to a repeating series of eclipses called a Saros cycle that repeats every 18 years 11 days and 8 hours.

There are now 40 active Saros cycles and the August 2017 eclipse belongs to Saros 145, which produced its first total eclipse in June 1909 and will produce its last total eclipse in September 2648.

## A tour of our solar system’s eclipses

In a meditative video for the NY Times, Dennis Overbye takes us on a tour of eclipses that happen in our solar system and beyond.

On the 21st day of August, 2017, the moon will slide between the Earth and the sun, painting a swath of darkness across North America. The Great American Solar Eclipse. An exercise in cosmic geometry. A reminder that we live on one sphere among many, all moving to the laws of Kepler, Newton and Einstein.

Humans have many more vantage points from which to observe solar eclipses than when the last solar eclipse occurred in the US in 1979. I had no idea that the Mars rovers had caught partial solar eclipses on Mars…so cool. (via @jossfong)

## A visual explanation of quantum mechanics

From the ViaScience YouTube channel comes this 31-part video explainer of quantum mechanics. As the introduction video notes, there is a fair bit of math in these videos presented at a quick pace, but if you took calculus in high school or college and remember the notation, that (and the pause button) should get you through this pretty well. (via @jsonpaul, who calls the series “fantastic”)

## Quantum entanglement effects observed over 100s of miles

A group of Chinese scientists say they have demonstrated the effects of quantum entanglement over a distance of 1200 km (745 miles).

Entanglement involves putting objects in the peculiar limbo of quantum superposition, in which an object’s quantum properties occupy multiple states at once: like Schrodinger’s cat, dead and alive at the same time. Then those quantum states are shared among multiple objects. Physicists have entangled particles such as electrons and photons, as well as larger objects such as superconducting electric circuits.

Theoretically, even if entangled objects are separated, their precarious quantum states should remain linked until one of them is measured or disturbed. That measurement instantly determines the state of the other object, no matter how far away. The idea is so counterintuitive that Albert Einstein mocked it as “spooky action at a distance.”

What’s weird to me is that all the articles I read about this touted that this happened in space, that an ultra-secure communications network was possible, or that we could build a quantum computer in space. Instantaneous communication over a distance of hundreds of miles is barely mentioned. Right now, it takes about 42 minutes for a round-trip communication between the Earth and Mars (and ~84 minutes for Jupiter). What if, when humans decide to settle on Mars, we could send a trillion trillion quantum entangled particles along with the homesteaders that could then be used to communicate in real time with people on Earth? I mean, how amazing would that be?

Update: Well, the simple reason why these articles don’t mention instantaneous communication at distance is that you can’t do it, even with quantum entanglement.

This is one of the most confusing things about quantum physics: entanglement can be used to gain information about a component of a system when you know the full state and make a measurement of the other component(s), but not to create-and-send information from one part of an entangled system to the other. As clever of an idea as this is, Olivier, there’s still no faster-than-light communication.

(thx, everyone)

## If you can’t explain something in simple terms, you don’t understand it

In the early 1960s, Richard Feynman gave a series of undergraduate lectures that were collected into a book called the Feynman Lectures on Physics. Absent from the book was a lecture Feynman gave on planetary motion, but a later finding of the notes enabled David Goodstein, a colleague of Feynman’s, to write a book about it: Feynman’s Lost Lecture. From an excerpt of the book published in a 1996 issue of Caltech’s Engineering & Science magazine:

Feynman was a truly great teacher. He prided himself on being able to devise ways to explain even the most profound ideas to beginning students. Once, I said to him, “Dick, explain to me, so that I can understand it, why spin one-half particles obey Fermi-Dirac statistics.” Sizing up his audience perfectly, Feynman said, “I’ll prepare a freshman lecture on it.” But he came back a few days later to say, “I couldn’t do it. I couldn’t reduce it to the freshman level. That means we don’t really understand it.”

John Gruber writes the simple explanations are the goal at Apple as well:

Engineers are expected to be able to explain a complex technology or product in simple, easily-understood terms not because the executive needs it explained simply to understand it, but as proof that the engineer understands it completely.

Feynman was well known for simple explanations of scientific concepts that result a in deeper understanding of the subject matter: e.g. see Feynman explaining how fire is stored sunshine, rubber bands, how trains go around curves, and magnets. Critically, he’s also not shy about admitting when he doesn’t understand something…or, alternately, when scientists as a group don’t understand something. There’s the spin anecdote above and of his explanation of magnets, he says:

I really can’t do a good job, any job, of explaining magnetic force in terms of something else you’re more familiar with, because I don’t understand it in terms of anything else you’re more familiar with.

Feynman was also quoted as saying:

I think I can safely say that nobody understands quantum mechanics.

Pretty interesting thing to hear from a guy who won a Nobel Prize for explaining quantum mechanics better than anyone ever had before. Even when he died in 1988 at the end of a long and fruitful careeer, a note at the top of his blackboard read:

What I cannot create, I do not understand.

## The absurd precision involved in detecting gravitational waves

Back in September 2015, the LIGO experiment detected gravitational waves formed 1.3 billion years ago when two black holes merged into one. The physics is pretty straightforward but to get the measurement, scientists had to build one of the most sensitive machines ever built. How sensitive? To get an accurate result, they needed to measure a distance of 4km with an accuracy of 1/10000th the width of a proton. This video from Veritasium looks at how the scientists and engineers accomplished such an amazing feat.

## What will the night sky look like in 5 million years?

Based on the motions of the 2 million stars observed by ESA’s Gaia mission over the past two years, scientists created this simulated animation of how the view of the Milky Way in the night sky will evolve over the next 5 million years.

The shape of the Orion constellation can be spotted towards the right edge of the frame, just below the Galactic Plane, at the beginning of the video. As the sequence proceeds, the familiar shape of this constellation (and others) evolves into a new pattern. Two stellar clusters — groups of stars that were born together and consequently move together — can be seen towards the left edge of the frame: these are the alpha Persei (Per OB3) and Pleiades open clusters.

Stars seem to move with a wide range of velocities in this video, with stars in the Galactic Plane moving quite slow and faster ones appearing over the entire frame. This is a perspective effect: most of the stars we see in the plane are much farther from us, and thus seem to be moving slower than the nearby stars, which are visible across the entire sky.

Well, how’s that for some perspective? (via blastr)

## The Orion Nebula, our friendly neighborhood star factory

Rolf Olsen recently took this amazing photo of the Orion Nebula using a home-built telescope.

The Orion Nebula is one of the most studied objects in the sky and also has a significant place in the history of astrophotography. In 1880 it was the first ever nebula to be photographed; Henry Draper used the newly invented dry plate process to acquire a 51-minute exposure of the nebula with an 11 inch telescope. Subsequently, in 1883, amateur astronomer Andrew Ainslie Common recorded several exposures up to 60 minutes long with a much larger 36-inch telescope, and showed for the first time that photography could reveal stars and details fainter than those visible to the human eye.

Thanks to Phil Plait for the link…he’s got much more to say about the image and the nebula here.

Also called M42 (the 42nd object in a catalog kept by comet hunter Charles Messier in the late 18th century), it is a sprawling star factory, a gas cloud where stars are born. It’s a couple of dozen light-years across, and sits well over a thousand light-years from Earth. That’s 10,000 trillion kilometers, and you can see it with your naked eye! It’s so bright because of a handful of extremely massive hot stars sit in its center. They blast out ultraviolet light that energizes the gas in the nebula, causing it to glow.

It’s actually a small section of a much larger dark cloud, what’s called a molecular cloud, that we cannot see directly. Stars were born near the edge of that cloud, not too deeply inside it, and when they switched on their fierce light and stellar winds blew a hole in the cloud, popping it like a bubble. The Orion Nebula is a cavity in the side of that cloud, carved by the newborn stars.

## A full rotation of the Moon

All but a few humans have seen no more than half of the Moon with their own eyes. For the rest of us stuck on Earth, we only get to see the side that always faces the Earth because the Earth & Moon are tidally locked; the Moon’s rotation about its axis and its orbit around the Earth take the same amount of time. But NASA’s LRO probe has taken high-resolution photos of all but 2% of the Moon’s surface, which have been stitched together into this video of the Moon’s full 360-degree rotation.

## Recreating the Asteroids arcade game with a laser

Watch as digital artist Seb Lee-Delisle recreates the old school video game Asteroids with a laser. But why use a laser? There’s actually a good explanation for this. In the olden days of arcade video games, the screens on most games were like Pac-Man or Donkey Kong…a typical CRT refreshed the entire screen line-by-line many times a second to form a pixelized scene. But with vector games like Tempest, Star Wars, and Asteroids, the electron beam was manipulated magnetically to draw the ships and rocks and enemies directly…and you get all these cool effects like phosphor trails and brighter objects where the beam lingers. When you play Asteroids on a contemporary computer or gaming system, all those artifacts are lost. But with a laser, you can emulate the original feel of the game much more closely.

You’re not going to want to because it’s 17 minutes long, but you should watch the whole video…it’s super nerdy and the explanations of how the various technologies work is worth your while (unless you’re already a laser expert). I loved the bit near the end where they slowed down the rate of the laser so you could see it drawing the game and then slowly sped it back up again, passing through the transition from seeing the individual movements of the laser to observing an entire seamless scene that our mind has stitched together. In his recent book Wonderland, Steven Johnson talks about this remarkable trick of the mind:

On some basic level, this property of the human eye is a defect. When we watch movies, our eyes are empirically failing to give an accurate report of what is happening in front of them. They are seeing something that isn’t there. Many technological innovations exploit the strengths that evolution has granted us: tools and utensils harness our manual dexterity and opposable thumbs; graphic interfaces draw on our powerful visual memory to navigate information space. But moving pictures take the opposite approach: they succeed precisely because our eyes fail.

This flaw was not inevitable. Human eyesight might have just as easily evolved to perceive a succession of still images as exactly that: the world’s fastest slide show. Or the eye might have just perceived them as a confusing blur. There is no evolutionary reason why the eye should create the illusion of movement at twelve frames per second; the ancestral environment where our visual systems evolved had no film projectors or LCD screens or thaumatropes. Persistence of vision is what Stephen Jay Gould famously called a spandrel — an accidental property that emerged as a consequence of other more direct adaptations. It is interesting to contemplate how the past two centuries would have played out had the human eye not possessed this strange defect. We might be living in a world with jet airplanes, atomic bombs, radio, satellites, and cell phones — but without television and movies. (Computers and computer networks would likely exist, but without some of the animated subtleties of modern graphical interfaces.) Imagine the twentieth century without propaganda films, Hollywood, sitcoms, the televised Nixon-Kennedy debate, the footage of civil rights protesters being fire-hosed, Citizen Kane, the Macintosh, James Dean, Happy Days, and The Sopranos. All those defining experiences exist, in part, because natural selection didn’t find it necessary to perceive still images accurately at rates above twelve frames a second — and because hundreds of inventors, tinkering with the prototypes of cinema over the centuries, were smart enough to take that imperfection and turn it into art.

## A fictional flight above real Mars

Using real images of Mars taken by the HiRISE camera on the Mars Reconnaissance Orbiter, Jan Fröjdman created a 3D-rendered flyover of several areas of the planet’s surface.

In this film I have chosen some locations and processed the images into panning video clips. There is a feeling that you are flying above Mars looking down watching interesting locations on the planet. And there are really great places on Mars! I would love to see images taken by a landscape photographer on Mars, especially from the polar regions. But I’m afraid I won’t see that kind of images during my lifetime.

It has really been time-consuming making these panning clips. In my 3D-process I have manually hand-picked reference points on the anaglyph image pairs. For this film I have chosen more than 33.000 reference points! It took me 3 months of calendar time working with the project every now and then.

Watch this in the highest def you can muster…gorgeous.

## The time crystals concept is now reality

In 2012, physicist Frank Wilczek speculated that it would be possible to make a crystal whose lattice repeats in four dimensions, not just three.

Wilczek thought it might be possible to create a similar crystal-like structure in time, which is treated as a fourth dimension under relativity. Instead of regularly repeating rows of atoms, a time crystal would exhibit regularly repeating motion.

Many physicists were sceptical, arguing that a time crystal whose atoms could loop forever, with no need for extra energy, would be tantamount to a perpetual motion machine — forbidden by the laws of physics.

Now, a team at Berkeley have succeeded in making time crystals, publishing a method that two other teams have already successfully followed.

For Yao’s time crystal, an external force — like the pulse of a laser — flips the magnetic spin of one ion in a crystal, which then flips the spin of the next, and so forth, setting the system into a repeating pattern of periodic motion.

There are two critical factors. First, after the initial driver, it must be a closed system, unable to interact with and lose energy to the environment. Second, interactions between quantum particles are the driving force behind the time crystal’s stability. “It’s an emergent phenomenon,” says Yao. “It requires many particles and many spins to talk to each other and collectively synchronise.”

## The leisurely pace of light speed

In a 45-minute video called Riding Light, Alphonse Swinehart animates the journey outward from the Sun to Jupiter from the perspective of a photon of light. The video underscores just how slow light is in comparison to the vast distances it has to cover, even within our own solar system. Light takes 8.5 minutes to travel from the Sun to the Earth, almost 45 minutes to Jupiter, more than 4 years to the nearest star, 100,000 years to the center of our galaxy, 2.5 million years to the nearest large galaxy (Andromeda), and 32 billion years to reach the most remote galaxy ever observed.1 The music is by Steve Reich (Music for 18 Musicians), whose music can also seem sort of endless.

If you’re impatient, you can watch this 3-minute version, sped up by 15 times:

1. This isn’t strictly true. As I understand it, a photon that just left the Sun will never reach that most remote galaxy.

## LIGO’s gravitational wave data may contradict relativity

Earlier this year, the LIGO experiment detected evidence of gravitational waves. Now the evidence shows that those waves may have echoes, which would contradict one of the tentpoles of modern physics, the general theory of relativity.

It was hailed as an elegant confirmation of Einstein’s general theory of relativity — but ironically the discovery of gravitational waves earlier this year could herald the first evidence that the theory breaks down at the edge of black holes. Physicists have analysed the publicly released data from the Laser Interferometer Gravitational-Wave Observatory (LIGO), and claim to have found “echoes” of the waves that seem to contradict general relativity’s predictions.

The echoes could yet disappear with more data. If they persist, the finding would be extraordinary. Physicists have predicted that Einstein’s hugely successful theory could break down in extreme scenarios, such as at the centre of black holes. The echoes would indicate the even more dramatic possibility that relativity fails at the black hole’s edge, far from its core.

If the echoes go away, then general relativity will have withstood a test of its power — previously, it wasn’t clear that physicists would be able to test their non-standard predictions.

## Carl Sagan explains the fourth dimension

From his seminal TV program Cosmos, Carl Sagan attempts to explain the fourth dimension of spacetime. The story starts with Edwin Abbott’s Flatland, but Sagan being Sagan, his explanation is especially lucid.

## The Map of Physics

In this video, physicist Dominic Walliman explains how all of the various disciplines of physics are related to each other by arranging them on a giant map. He starts with the three main areas — classical physics, quantum mechanics, and relativity — and then gets into the more specific subjects like optics, electromagnetism, and particle physics before venturing across The Chasm of Ignorance (dun dun DUN!) where things like string theory and dark matter dwell.

## NASA’s analysis of seemingly impossible engine: it works

NASA has published their highly anticipated and peer-reviewed analysis of the EM Drive and they’ve concluded the engine works despite appearing to violate Newton’s third law of motion.

In case you’ve missed the hype, the EM Drive, or Electromagnetic Drive, is a propulsion system first proposed by British inventor Roger Shawyer back in 1999.

Instead of using heavy, inefficient rocket fuel, it bounces microwaves back and forth inside a cone-shaped metal cavity to generate thrust.

According to Shawyer’s calculations, the EM Drive could be so efficient that it could power us to Mars in just 70 days.

But, there’s a not-small problem with the system. It defies Newton’s third law, which states that everything must have an equal and opposite reaction.

According to the law, for a system to produce thrust, it has to push something out the other way. The EM Drive doesn’t do this.

Yet in test after test it continues to work. Last year, NASA’s Eagleworks Laboratory team got their hands on an EM Drive to try to figure out once and for all what was going on.

There’s a lot of skepticism around this project, but NASA’s review is definitely a boost to the EM Drive’s credibility.

Update: Just to reiterate, even with this latest paper, there is still skepticism about the EM Drive.

In the end, we can’t conclude that this is a null result, nor can we excitedly say that it works. The sad truth is that this paper is not much better than the researchers’ last one, and it doesn’t actually have enough detail to let us fully evaluate the data. Nor does the paper have enough data to allow a conclusion in the absence of a model. And despite mention of a model in the paper, any model that exists is very well hidden.

Also a clue that the science isn’t quite there on this one yet: very few mainstream science outlets covered this. When the NY Times picks this up and gets prominent physicists on the record about the thruster’s promise, that’s when you’ll know something’s up. Until then, remain skeptical. (via @paudo)

## The Most Efficient Way to Destroy the Universe

Kurzgesagt shares a speculative bit of physics called vacuum decay that could very efficiently erase the entire Universe.

To understand vacuum decay, you need to consider the Higgs field that permeates our Universe. Like an electric field, the Higgs field varies in strength, based on its potential. Think of the potential as a track on which a ball is rolling. The higher it is on the track, the more energy the ball has.

The Higgs potential determines whether the Universe is in one of two states: a true vacuum, or a false vacuum. A true vacuum is the stable, lowest-energy state, like sitting still on a valley floor. A false vacuum is like being nestled in a divot in the valley wall — a little push could easily send you tumbling. A universe in a false vacuum state is called “metastable”, because it’s not actively decaying (rolling), but it’s not exactly stable either.

There are two problems with living in a metastable universe. One is that if you create a high enough energy event, you can, in theory, push a tiny region of the universe from the false vacuum into the true vacuum, creating a bubble of true vacuum that will then expand in all directions at the speed of light. Such a bubble would be lethal.

Such a process could already be underway, but don’t worry:

But even if one or multiple spheres of death have already started expanding, the Universe is so big they might not reach us for billions of years.

## Scientists accidentally discover a process to turn CO2 into fuel

Scientists at Oak Ridge National Laboratory have stumbled upon a process that uses “nanospikes” to turn carbon dioxide into ethanol, a common fuel.

This process has several advantages when compared to other methods of converting CO2 into fuel. The reaction uses common materials like copper and carbon, and it converts the CO2 into ethanol, which is already widely used as a fuel.

Perhaps most importantly, it works at room temperature, which means that it can be started and stopped easily and with little energy cost. This means that this conversion process could be used as temporary energy storage during a lull in renewable energy generation, smoothing out fluctuations in a renewable energy grid.

This sounds like a big deal…is it now possible to limit the effects of climate change by sinking carbon while also placing less dependence on fossil fuels? Here’s the Oak Ridge press release. That this news is almost a week old already and we haven’t heard more about it makes me a bit skeptical as to the true importance of it. (Of course, CRISPR is potentially a massive deal and we don’t hear about it nearly enough so…)

Update: A relevant series of tweets from Eric Hittinger on “why creating ethanol from CO2 cannot solve our energy or climate problems”. Wasn’t fully awake when I posted this apparently because, yeah, duh. (via @leejlh)

## A well-designed reissue of Newton’s Principia

Small Spanish publisher Kronecker Wallis is doing a Kickstarter campaign to print a well-designed version of Isaac Newton’s Principia, one of the most important texts in science.

We have spent several months working on a desire. The desire to have a new edition of Isaac Newton’s Principia in our hands that is on a par with the importance of the text and of modern editorial design. To put it back on our shelves so that we can leaf through it from time to time and feel the pages beneath our fingers.

An opportunity has now arisen. Taking advantage of the fact that the original publication is to celebrate its 330th anniversary in 2017, we wish to republish it with an editorial design that pays attention to every last detail.

I am enjoying this trend of reviving old classics through the lens of modern design and packaging; see also the NYCTA Graphics Standards Manual, the NASA Graphics Standards Manual, and the Voyager Golden Record.

## Richard Feynman’s Tiny Machines

In 1959, physicist Richard Feynman, who had already done work that would win him the Nobel Prize a few years later, gave a talk at Caltech that didn’t have much to do with his main areas of study. The talk was called There’s Plenty of Room at the Bottom and it was a scientist at the peak of his formidable powers asking a question of the scientific community: What about nanotechnology?

I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle. This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, “What are the strange particles?”) but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations. Furthermore, a point that is most important is that it would have an enormous number of technical applications.

Even though he made no formal contribution to the field, Feynman’s talk has been credited with jumpstarting interest in the study of nanotechnology. No recording exists of the original talk, but in 1984, Feynman gave a talk he called Tiny Machines, in which he recalled his original talk and spoke of the progress that had been made over the past 25 years. (via @ptak)

## How German physicists reacted to the Hiroshima bomb

During World War II, a group of scientists led by Werner Heisenberg worked on designing a nuclear weapon for Nazi Germany. They were, thankfully, unsuccessful. After the war, the Allies detained ten German scientists in England for six months. Hoping to learn about the German bomb program, they secretly taped the scientists’ conversations. In August 1945, the scientists were told about the US dropping a nuclear bomb on Japan. Here’s a transcript of the resulting reaction and conversation.

Shortly before dinner on the 6th August I informed Professor HAHN that an announcement had been made by the B.B.C. that an atomic bomb had been dropped. HAHN was completely shattered by the news and said that he felt personally responsible for the deaths of hundreds of thousands of people, as it was his original discovery which had made the bomb possible. He told me that he had originally contemplated suicide when he realized the terrible potentialities of his discovery and he felt that now these had been realized and he was to blame. With the help of considerable alcoholic stimulant he was calmed down and we went down to dinner where he announced the news to the assembled guests.

“Professor HAHN” is Otto Hahn, who co-discovered nuclear fission in Germany right before the war and won the 1944 Nobel Prize in Chemistry for it. The rest of the world may have gotten there eventually, but think of how different the war (and resulting Cold War period) would have been if Germany had sequestered their scientific progress a couple years earlier or if Hahn and Lise Meitner had made the discovery a year or two later.

WEIZSÄCKER: I think it’s dreadful of the Americans to have done it. I think it is madness on their part.

HEISENBERG: One can’t say that. One could equally well say “That’s the quickest way of ending the war.”

HAHN: That’s what consoles me.

HAHN: I was consoled when, I believe it was WEIZSÄCKER said that there was now this uranium - I found that in my institute too, this absorbing body which made the thing impossible consoled me because when they said at one time one could make bombs, I was shattered.

WEIZSÄCKER: I would say that, at the rate we were going, we would not have succeeded during this war.

HAHN: Yes.

WEIZSÄCKER: It is very cold comfort to think that one is personally in a position to do what other people would be able to do one day.

I particularly like Heisenberg’s distinction between between theoretical and applied science:

There is a great difference between discoveries and inventions. With discoveries one can always be skeptical and many surprises can take place. In the case of inventions, surprises can really only occur for people who have not had anything to do with it. It’s a bit odd after we have been working on it for five years.

If this stuff interests you at all, I’d highly recommend reading Richard Rhodes’ The Making of the Atomic Bomb. (via real future)

Update: The complete transcripts of the secret recordings were collected into a book called Hitler’s Uranium Club. The story of the Allied sabotage of a key element in producing a German bomb is told in Neal Bascomb’s The Winter Fortress. Alex Wellerstein writes that the Nazis didn’t know very much about the Manhattan Project. (via @CarnegieDeputy, @hellbox, @AtomicHeritage)

## Meet the nano sapiens

In a 1959 talk at Caltech titled There’s Plenty of Room at the Bottom, Richard Feynman outlined a new field of study in physics: nanotechnology. He argued there was much to be explored in the realm of the very small — information storage, more powerful microscopes, biological research, computing — and that that exploration would be enormously useful.

I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle. This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, “What are the strange particles?”) but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations. Furthermore, a point that is most important is that it would have an enormous number of technical applications.

In a reaction to Elon Musk’s plan to colonize Mars, David Galbraith suggests there might be plenty of room at the bottom for human civilization as well. Don’t colonize Mars, miniaturize humanity. Create nano sapiens.

If we think of this as a design problem, there is a much better solution. Instead of expanding our environment to another planet at massive cost, why wouldn’t we miniaturise ourselves so we can expand without increasing our habitat or energy requirements, but still maintain our ability to create culture and knowledge, via information exchange.

The history of information technology and the preservation of Moore’s law has been driven by exactly this phenomenon of miniaturization. So why shouldn’t the same apply to the post technological evolution of humankind as it approaches the hypothetical ‘singularity’ and the potential ability for us to be physically embodied in silicon rather than carbon form.

When humans get smaller, the world and its resources get bigger. We’d live in smaller houses, drive smaller cars that use less gas, eat less food, etc. It wouldn’t even take much to realize gains from a Honey, I Shrunk Humanity scheme: because of scaling laws, a height/weight proportional human maxing out at 3 feet tall would not use half the resources of a 6-foot human but would use somewhere between 1/4 and 1/8 of the resources, depending on whether the resource varied with volume or surface area. Six-inch-tall humans would potentially use 1728 times fewer resources.1

Galbraith also speculates about nano aliens as a possible explanation for the Fermi paradox:

Interestingly, the same rules of energy use and distance between planets and stars would apply to any extraterrestrial aliens, so one possible explanation for the Fermi paradox is that we all get smaller and less visible as we get more technologically advanced. Rather than favoring interstellar colonization with its mind boggling distances which are impossible to communicate across within the lifetimes of individuals (and therefore impossible to hold together in any meaningful way as a civilization) perhaps advanced civilizations stick to their home planets but just get more efficient to be sustainable.

Humans are explorers. Curiosity about new worlds and ideas is one of humanity’s defining traits. One of the most striking things about the Eames’ Powers of Ten video is how similar outer space and inner space look — vast distances punctuated occasionally by matter. What if, instead of using more and more energy exploring planets, stars, and galaxies across larger and larger distances (the first half of the Eames’ video), we went the other way and focused on using less energy to explore cells, molecules, and atoms across smaller and smaller distances. It wouldn’t be so much giving up human space exploration as it would be exchanging it for a very similar and more accessible exploration of the molecular and atomic realm. There is, after all, plenty of room down there.

Update: I knew the responses to this would be good. Galbraith’s idea has a name: the transcension hypothesis, formulated by the aptly named John Smart. Jason Silva explains in this video:

The transcension hypothesis proposes that a universal process of evolutionary development guides all sufficiently advanced civilizations into what may be called “inner space,” a computationally optimal domain of increasingly dense, productive, miniaturized, and efficient scales of space, time, energy, and matter, and eventually, to a black-hole-like destination. Transcension as a developmental destiny might also contribute to the solution to the Fermi paradox, the question of why we have not seen evidence of or received beacons from intelligent civilizations.

Before we get there, however, there are a few challenges we need to overcome, as Joe Hanson explains in The Small Problem With Shrinking Ourselves:

As it often seems in such matters, science follows science fiction here. In Kurt Vonnegut’s Slapstick (Amazon), the Chinese miniaturize themselves in response to the Earth’s decreasing resources.

In the meantime, Western civilization is nearing collapse as oil runs out, and the Chinese are making vast leaps forward by miniaturizing themselves and training groups of hundreds to think as one. Eventually, the miniaturization proceeds to the point that they become so small that they cause a plague among those who accidentally inhale them, ultimately destroying Western civilization beyond repair.

Blood Music by Greg Bear (Amazon) has a nano-civilization theme:

Through infection, conversion and assimilation of humans and other organisms the cells eventually aggregate most of the biosphere of North America into a region seven thousand kilometres wide. This civilization, which incorporates both the evolved noocytes and recently assimilated conventional humans, is eventually forced to abandon the normal plane of existence in favor of one in which thought does not require a physical substrate.

James Blish’s short story Surface Tension tells the tale of microscopic human colonists. (via @harryh, @mariosaldana, @EndlessForms, @vanjacosic, @chumunculus)

Update: For some years, director Alexander Payne has been working on a film called Downsizing:

“Downsizing,” after all, starts off in Norway and takes place in a not-too-distant future where humans are now able to shrink themselves to 1/8 their size as a means to battle over-consumption and the rapid depletion of earth’s natural resources, thanks to enlightened hippie-like Scandinavian scientists. “Smalls” get small, then become members of small cities (the main characters moves to a city called Leisureland) protected by large nets (keeps the bugs out) and built like Disney’s Celebration Town (all planned, all pre-fabricated). Small people cash-in their savings and retire small; 1 big dollar equals 500 small dollars. Smalls live on less food, less land, and produce less trash. As the story progresses, Americans are free to get small, but in Europe, where resources are beginning to truly run out, legislation arises suggesting 40% of the population get shrunk (whether they like it or not). For the big, the world grows smaller and scarier; for the small, the world grows bigger and scarier.

Word is that Matt Damon will play the lead role. Mr. Payne, consider a title change to “Nano Sapiens”? (via @stephenosberg)

Photo by Poy.

1. This is not a straightforward matter however. The 6-inch human wouldn’t eat 1728 times less food…that would mean you could live on a Big Mac for a year. Small animals often eat a significant percentage of their body weights each day, which normal-sized humans never approach. For example, according to this chart a grey squirrel weighs about 21 oz and eats about 1.6 oz of food, the equivalent of a 180-pound human eating about 14 pounds of food a day.

## A year-long time lapse of the Earth rotating in space

NASA recently released a time lapse video of the Earth constructed from over 3000 still photographs taken over the course of a year. The photos were taken by a camera mounted on the NOAA’s DSCOVR satellite, which is perched above the Earth at Lagrange point 1.

Wait, have we talked about Lagrange points yet? Lagrange points are positions in space where the gravity of the Sun and the Earth (or between any two large things) cancel each other out. The Sun and the Earth pull equally on objects at these five points.

L1 is about a million miles from Earth directly between the Sun and Earth and anything that is placed there will hover there relative to the Earth forever (course adjustments for complicated reasons aside). It is the perfect spot for a weather satellite with a cool camera to hang out, taking photos of a never-dark Earth. In addition to DSCOVR, at least five other spacecraft have been positioned at L1.

L2 is about a million miles from the Earth directly opposite L1. The Earth always looks dark from there and it’s mostly shielded from solar radiation. Five spacecraft have lived at L2 and several more are planned, including the sequel to the Hubble Space Telescope. Turns out that the shadow of the Earth is a good place to put a telescope.

L3 is opposite the Earth from the Sun, the 6 o’clock to the Earth’s high noon. This point is less stable than the other points because the Earth’s gravitational influence is very small and other bodies (like Venus) periodically pass near enough to yank whatever’s there out, like George Clooney strolling through a country club dining room during date night.

And quoting Wikipedia, “the L4 and L5 points lie at the third corners of the two equilateral triangles in the plane of orbit whose common base is the line between the centers of the [Earth and Sun]”. No spacecraft have ever visited these points, but they are home to some interplanetary dust and asteroid 2010 TK7, which orbits around L4. Cool! (via slate)

## On the Origins of Life, Meaning, and the Universe Itself

After an unbelievably stressful and busy winter/spring, I am hoping to find some time to read this summer. One of the books on my short list is Sean Carroll’s The Big Picture, one of those “everything is connected” things I love. From a post by Carroll on what the book’s about:

This book is a culmination of things I’ve been thinking about for a long time. I’ve loved physics from a young age, but I’ve also been interested in all sorts of “big” questions, from philosophy to evolution and neuroscience. And what these separate fields have in common is that they all aim to capture certain aspects of the same underlying universe. Therefore, while they are indisputably separate fields of endeavor — you don’t need to understand particle physics to be a world-class biologist — they must nevertheless be compatible with each other — if your theory of biology relies on forces that are not part of the Standard Model, it’s probably a non-starter. That’s more of a constraint than you might imagine. For example, it implies that there is no such thing as life after death. Your memories and other pieces of mental information are encoded in the arrangement of atoms in your brain, and there’s no way for that information to escape your body when you die.

Yeah, that sounds right up my alley.