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Huzzah! Long unavailable (or at least not widely available), Errol Morris’ documentary film on Stephen Hawking and his work, A Brief History of Time, is now available for rent or purchase on iTunes. Or if you can wait a little bit, there’s a Criterion Blu-ray edition coming out in mid-March. Bonus: score by Philip Glass!
What would happen if a tiny black hole the size of a marble were placed at the center of the Earth? Rest assured, the Earth won’t completely be swallowed up by the black hole but that’s really the only good news to offer.
First of all, not all of the Earth would simply be sucked into the black hole. When the matter near the black hole begins to fall into the black hole, it will be compressed to a very high density that will cause it to be heated to very high temperatures. These high temperatures will cause gamma rays, X-rays, and other radiation to heat up the other matter falling in to the black hole. The net effect will be that there will be a strong outward pressure on the outer layers of the Earth that will first slow down their fall and will eventually ionize and push the outer layers away from the black hole. So some inner portion of the core will fall into the black hole, but the outer layers, including the crust and all of us, would be vaporized to a high temperature plasma and blown into space.
This would be a gigantic explosion — a significant fraction of the rest of the mass of the Earth matter that actually fell into the black hole will be converted into energy.
FYI, that marble-sized black hole would have about the same mass as the Earth. Not that they exist, mind you. Maybe, maybe not. Blackish holes? Dark grey holes? Anyway, really heavy.
In 1976, legendary cosmologist and astronomer Carl Sagan tried to recruit a 17-year-old Neil deGrasse Tyson to Cornell University. In April of that year, Tyson wrote Sagan a letter informing him of his intention to enroll at Harvard instead:
The Viking Missions referred to in the letter were the two probes sent to Mars in the mid-1970s.
Tyson occupies a role in today’s society similar to Sagan’s in the 1980s as an unofficial public spokesman of the wonderous world of science. Tyson is even hosting an updated version of Sagan’s seminal Cosmos series for Fox, which debuts on March 9th. Here’s a trailer:
Letter courtesy of The Seth Macfarlane Collection of the Carl Sagan and Ann Druyan Archive at the Library of Congress, which is chock full of great Sagan stuff. And yeah, that’s Seth Macfarlane, creator of Family Guy and much-maligned host of the Oscars. Macfarlane was a big fan of the original Cosmos series and was instrumental in getting the new series made. (via @john_overholt)
In a short video from The Atlantic, science writer Philip Ball explains why Isaac Newton picked ROYGBIV (red, orange, yellow, green, blue, indigo, and violet) for the colors of the spectrum and not 3 or 6 or even 16 other possible colors.
Newton was the first to demonstrate through his famous prism experiments that color is intrinsic to light. As part of those experiments, he also divvied up the spectrum in his own idiosyncratic way, giving us ROYGBIV. Why indigo? Why violet? We don’t really know why Newton decided there were two distinct types of purple, but we do know he thought there should be seven fundamental colors.
Ball is the author of Bright Earth: Art and the Invention of Color, which looks pretty interesting. His mention in the video of the changing perception of color throughout history reminds me of my favorite segment of Radiolab, which covers that very topic.
In a thread about the newly visible supernova in the M82 galaxy, MetaFilter user Ivan Fyodorovich offered up this plain-English explanation of what happens when a star dies and goes supernova. It’s a great read.
It will take it just 6 months to burn up its oxygen. Again, when there’s not enough oxygen being fused to generate energy to balance the pressure of gravitational contraction, the star begins to shrink, almost doubling the temperature, tripling the density, and causing the silicon (which was produced by the oxygen fusion) to begin fusing, in its own complicated sequence involving the alpha process, with the end result of nickel-56 (which radioactively decays into cobalt-56 and iron-56). This, as before, balances against the gravitational pressure and returns the star to equilibrium.
And now it will take merely 1 day to burn up its silicon. Finally, when there’s not enough silicon being fused to generate energy to balance the pressure of gravitational contraction, the star begins to shrink.
This time, however, the core of the star is mostly nickel and iron, and they cannot ordinarily be fused into heavier elements, so as the star shrinks and the temperature and density increase, there is no nuclear fusion ignition of the nickel and iron to counteract the contraction. Here the limit of pressure and density is the electron degeneracy pressure, which is the resistance of electrons being forced to occupy the same energy states, which they can’t.
(via @mathowie)
In an “only Nixon can go to China” moment in physics, Stephen Hawking now says “there are no black holes”.
Most physicists foolhardy enough to write a paper claiming that “there are no black holes” — at least not in the sense we usually imagine — would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.
In its stead, Hawking’s radical proposal is a much more benign “apparent horizon”, which only temporarily holds matter and energy prisoner before eventually releasing them, albeit in a more garbled form.
A supernova erupted recently1 in galaxy M82, a mere 11.4 million light years away from Earth, which means that it was close enough to be discovered by someone using an ordinary telescope in London and may be visible with binoculars sometime in the next two weeks.
M82’s proximity means that there are many existing images of it, pre-explosion, including some from the Hubble Space Telescope. Cao and others will comb through those images, looking for what lay in the region before. It will not be easy: M82 is filled with dust. But the light the supernova shines on the dust could teach astronomers something about the host galaxy, too. One team is already looking for radioactive elements, such as nickel, that theories predict form in such supernova, says Shri Kulkarni, an astronomer at California Institute of Technology. “Dust has its own charms.”
Ok, it didn’t erupt recently. M82 is 11.4 million light years away, so the supernova happened 11.4 million years ago and the light is just now reaching us here on Earth.↩
First of all, how cute are these foxes jumping up and diving down into the snow after mice?
So. Cute. Here’s Robert Krulwich on what they’re up to:
Think about this … an ordinary fox can stalk a mole, mouse, vole or shrew from a distance of 25 feet, which means its food is making a barely audible rustling sound, hiding almost two car lengths away. And yet our fox hurls itself into the air — in an arc determined by the fox, the speed and trajectory of the scurrying mouse, any breezes, the thickness of the ground cover, the depth of the snow — and somehow (how? how?), it can land straight on top of the mouse, pinning it with its forepaws or grabbing the mouse’s head with its teeth.
Look at those ears and how the fox moves his head around to zero in on the mouse’s location…reminds me of the pre-radar acoustic location devices (sometimes called war tubas) used in the early 20th century to detect approaching aircraft:
Let slip the tubas of war! Aaaaanyway, as the acoustic location device gave way to the more effective radar, so too is the fox more successful at hunting when he is pointed northeast — a kind of magnetic radar, if you will. Fascinating.
A pair of scientists recently searched the internet for evidence of time travel.
Here, three implementations of Internet searches for time travelers are described, all seeking a prescient mention of information not previously available. The first search covered prescient content placed on the Internet, highlighted by a comprehensive search for specific terms in tweets on Twitter. The second search examined prescient inquiries submitted to a search engine, highlighted by a comprehensive search for specific search terms submitted to a popular astronomy web site. The third search involved a request for a direct Internet communication, either by email or tweet, pre-dating to the time of the inquiry. Given practical verifiability concerns, only time travelers from the future were investigated.
Spoiler: they didn’t find any. (via @CharlesCMann)
Inspired by the escalating blade count of the razor industry, Nabisco has developed a new snack called the Quadriscuit.
“At the moment, this hyperwafer can only exist for six milliseconds in a precisely calibrated field of magnetic energy, positrons, roasted garlic, and beta particles,” lab chief Dr. Paul Ellison told reporters at a press conference outside Nabisco’s $200 million seven-whole-grain accelerator.
The last line of the piece made me LOL for real. (thx, meg)
Using a large piece of spandex (representing spacetime) and some balls and marbles (representing masses), a high school science teacher explains how gravity works.
The bits about how the planets all orbit in the same direction and the demo of the Earth/Moon orbit are really neat. And you can stop watching around the 7-minute mark…the demos end around then.
Update: Here’s another video of a similar system with some slightly different demos.
Hans Bethe was a giant in the field of nuclear physics. He rubbed shoulders with Einstein, Bohr, and Pauli, was head of the Theoretical Division of the US atomic bomb project, and was awarded a Nobel Prize. In 1999, at the age of 93, Bethe gave a series of three lectures to the residents of his retirement community near Cornell University, where he had taught since 1935. Video of the lectures is available on the Cornell website.
In the first lecture, Bethe covers the development of the “old quantum theory”, covering the work of Max Planck and Niels Bohr. In the second and third lectures, he relates how modern quantum mechanics was developed, with a healthy amount of personal recollection along the way:
Professor Bethe offers personal anecdotes about many of the famous names commonly associated with quantum physics, including Bohr, Heisenberg, Born, Pauli, de Broglie, Schrödinger, and Dirac.
Without a doubt, this is the most high-power presentation ever made at a retirement home. (via @stevenstrogatz)
Google and NASA recently bought a D-Wave quantum computer. But according to a piece by Sophie Bushwick published on the Physics Buzz Blog, there isn’t scientific consensus on whether the computer is actually using quantum effects to calculate.
In theory, quantum computers can perform calculations far faster than their classical counterparts to solve incredibly complex problems. They do this by storing information in quantum bits, or qubits.
At any given moment, each of a classical computer’s bits can only be in an “on” or an “off” state. They exist inside conventional electronic circuits, which follow the 19th-century rules of classical physics. A qubit, on the other hand, can be created with an electron, or inside a superconducting loop. Obeying the counterintuitive logic of quantum mechanics, a qubit can act as if it’s “on” and “off” simultaneously. It can also become tightly linked to the state of its fellow qubits, a situation called entanglement. These are two of the unusual properties that enable quantum computers to test multiple solutions at the same time.
But in practice, a physical quantum computer is incredibly difficult to run. Entanglement is delicate, and very easily disrupted by outside influences. Add more qubits to increase the device’s calculating power, and it becomes more difficult to maintain entanglement.
(via fine structure)
Not to get all Malcolm Gladwell here, but it’s counterintuitive that hot water freezes faster than cold water. The phenomenon is called the Mpemba effect and until recently, no one could explain how it works. A group of researchers in Singapore think they’ve cracked the puzzle.
Now Xi and co say hydrogen bonds also explain the Mpemba effect. Their key idea is that hydrogen bonds bring water molecules into close contact and when this happens the natural repulsion between the molecules causes the covalent O-H bonds to stretch and store energy.
But as the liquid warms up, it forces the hydrogen bonds to stretch and the water molecules sit further apart. This allows the covalent molecules to shrink again and give up their energy. The important point is that this process in which the covalent bonds give up energy is equivalent to cooling.
In fact, the effect is additional to the conventional process of cooling. So warm water ought to cool faster than cold water, they say. And that’s exactly what is observed in the Mpemba effect.
(via ★djacobs)
This video dicusses three simple ways to travel through time (all of which you can do right now at home) and three not-so-simple time travel methods.
For more on time-travel, here are some works by physicist and time-lord Sean Carroll:
Rules for time-travellers - http://blogs.discovermagazine.com/cos…
Learn more about time and time-machines in his book From Eternity to Here - http://preposterousuniverse.com/etern…
Visualizations of the spinning universe - http://iopscience.iop.org/1367-2630/1…
An engaging talk on the Paradoxes of Time Travel - https://vimeo.com/11917849
(via digg)
NASA’s Solar Dynamics Observatory is getting some really amazing shots of the Sun, including this 200,000 mile-long solar eruption that left a huge canyon on the surface of the Sun:
Different wavelengths help capture different aspect of events in the corona. The red images shown in the movie help highlight plasma at temperatures of 90,000° F and are good for observing filaments as they form and erupt. The yellow images, showing temperatures at 1,000,000° F, are useful for observing material coursing along the sun’s magnetic field lines, seen in the movie as an arcade of loops across the area of the eruption. The browner images at the beginning of the movie show material at temperatures of 1,800,000° F, and it is here where the canyon of fire imagery is most obvious.
The level of detail shown is incredible. (via @DavidGrann)
For the New York Review of Books, theoretical physicist and Nobel laureate Steven Weinberg gives us an update on what we know and don’t know about physics.
It turns out that particles already known to us are not enough to account for the mass of the hot matter in which the sound waves must have propagated. Fully five sixths of the matter of the universe would have to be some kind of “dark matter,” which does not emit or absorb light. The existence of this much dark matter in the present universe had already been inferred from the fact that clusters of galaxies hold together gravitationally, despite the high random speeds of the galaxies in the clusters. So this is a great puzzle: What is the dark matter? Theories abound, and attempts are underway to catch ambient dark matter particles or remnants of their annihilation in detectors on Earth or to create dark matter in accelerators. But so far dark matter has not been found, and no one knows what it is.
Google’s got themselves a quantum computer (they’re sharing it with NASA) and they made a little video about it:
I’m sure that Hartmut is a smart guy and all, but he’s got a promising career as an Arnold Schwarzenegger impersonator hanging out there if the whole Google thing doesn’t work out.
Light (aka electromagnetic radiation) is responsible for most of what we know about the universe. By measuring photons of various frequencies in different ways — “the careful collection of ancient light” — we’ve painted a picture of our endless living space. But light isn’t perfect. It can bend, scatter, and be blocked. Changes in gravity are more difficult to detect, but new instruments may allow scientists to construct a different map of the universe and its beginnings.
LIGO works by shooting laser beams down two perpendicular arms and measuring the difference in length between them-a strategy known as laser interferometry. If a sufficiently large gravitational wave comes by, it will change the relative length of the arms, pushing and pulling them back and forth. In essence, LIGO is a celestial earpiece, a giant microphone that listens for the faint symphony of the hidden cosmos.
Like many exotic physical phenomena, gravitational waves originated as theoretical concepts, the products of equations, not sensory experience. Albert Einstein was the first to realize that his general theory of relativity predicted the existence of gravitational waves. He understood that some objects are so massive and so fast moving that they wrench the fabric of spacetime itself, sending tiny swells across it.
How tiny? So tiny that Einstein thought they would never be observed. But in 1974 two astronomers, Russell Hulse and Joseph Taylor, inferred their existence with an ingenious experiment, a close study of an astronomical object called a binary pulsar [see “Gravitational Waves from an Orbiting Pulsar,” by J. M. Weisberg et al.; Scientific American, October 1981]. Pulsars are the spinning, flashing cores of long-exploded stars. They spin and flash with astonishing regularity, a quality that endears them to astronomers, who use them as cosmic clocks. In a binary pulsar system, a pulsar and another object (in this case, an ultradense neutron star) orbit each other. Hulse and Taylor realized that if Einstein had relativity right, the spiraling pair would produce gravitational waves that would drain orbital energy from the system, tightening the orbit and speeding it up. The two astronomers plotted out the pulsar’s probable path and then watched it for years to see if the tightening orbit showed up in the data. The tightening not only showed up, it matched Hulse and Taylor’s predictions perfectly, falling so cleanly on the graph and vindicating Einstein so utterly that in 1993 the two were awarded the Nobel Prize in Physics.
Friday morning is as good a time as any to revisit what I consider one of the quintessential Kottke.org post(s), The case of the plane and conveyor belt. Essentially, will an airplane take off on a treadmill. Prompted by a question on The Straight Dope, the post, now over 7 years old, has everything you need for a Kottke.org post: airplanes, physics, a waffle, and careful consideration of the facts. The question was addressed again a few days later to definitively and succinctly put the argument to rest.
Now that I’ve closed the comments on the question of the airplane and the conveyor belt, I’m still getting emails calling me an idiot for thinking that the plane will take off. Having believed that after first hearing the question and formulating several reasons reinforcing my belief, I can sympathize with that POV, but that doesn’t change the fact that I was initially wrong and that if you believe the plane won’t take off, you’re wrong too.
A 2008 liveblog of an episode of Mythbusters, further cemented the following notion:
For what it’s worth commenters almost everywhere continue to disagree. For more opinions, see here, here, here, here.
I had no idea that’s how rubber bands worked. Once again, Feynman takes something that seems pretty simple and makes it both simpler and vividly complex.
(via @stevenstrogatz)
Volume 1 of The Feynman Lectures on Physics is now available in HTML form. What a fantastic resource.
Nearly fifty years have passed since Richard Feynman taught the introductory physics course at Caltech that gave rise to these three volumes, The Feynman Lectures on Physics. In those fifty years our understanding of the physical world has changed greatly, but The Feynman Lectures on Physics has endured. Feynman’s lectures are as powerful today as when first published, thanks to Feynman’s unique physics insights and pedagogy. They have been studied worldwide by novices and mature physicists alike; they have been translated into at least a dozen languages with more than 1.5 millions copies printed in the English language alone. Perhaps no other set of physics books has had such wide impact, for so long.
I took a Greek and Roman literature class in college. Among the texts we studied was Lucretius’ On The Nature of Things. Shamefully, about the only thing I remembered from it was that the poem was an early articulation of the concept of atoms (see also Democritus). Impressive, chatting about atoms in 50 BCE. But reading Stephen Greenblatt’s The Swerve has reminded me what an impressive and prescient document it is, quite apart from its beauty as a poem. In chapter eight of his book, Greenblatt summarizes the main points of Lucretius’ poem:
Everything is made of invisible particles.
The elementary particles of matter — “the seeds of things” — are eternal.
The elementary particles are infinite in number but limited in shape and size.
All particles are in motion in an infinite void.
The universe has no creator or designer.
Everything comes into being as a result of a swerve.
[Ok, the swerve deserves a bit of explanation. Here’s Greenblatt:
If all the individual particles, in their infinite numbers, fell through the void in straight lines, pulled down by their own weight like raindrops, nothing would ever exist. But the particles do no move lockstep in a preordained single direction. Instead, “at absolutely unpredictable time and places they deflect slightly from their straight course, to a degree that could be described as no more than a shift of movement.” The position of the elementary particles is thus indeterminate.
I can’t help but think of quantum mechanics here. Anyway, back to the list.]
The swerve is the source of free will.
Nature ceaselessly experiments.
The universe was not created for or about humans.
Humans are not unique.
Human society began not in a Golden Age of tranquility and plenty, but in a primitive battle for survival.
The soul dies.
There is no afterlife.
Death is nothing to us.
All organized religions are superstitious delusions.
Religions are invariably cruel.
There are no angels, demons, or ghosts.
The highest goal of human life is the enhancement of pleasure and the reduction of pain.
The greatest obstacle to pleasure is not pain; it is delusion.
Understanding the nature of things generates deep wonder.
The seeds of atomic theory, quantum mechanics, evolution, agnosticism, atheism…they’re all right there, in a poem written by a man who died more than 2000 years ago.
If you’re at all interested in the Pioneer Anomaly (and you really should be, it’s fascinating), The Pioneer Detectives ebook by Konstantin Kakaes looks interesting.
Explore one of the greatest scientific mysteries of our time, the Pioneer Anomaly: in the 1980s, NASA scientists detected an unknown force acting on the spacecraft Pioneer 10, the first man-made object to journey through the asteroid belt and study Jupiter, eventually leaving the solar system. No one seemed able to agree on a cause. (Dark matter? Tensor-vector-scalar gravity? Collisions with gravitons?) What did seem clear to those who became obsessed with it was that the Pioneer Anomaly had the potential to upend Einstein and Newton — to change everything we know about the universe.
Kakaes was a science writer for The Economist and studied physics at Harvard, so this topic seems right up his alley. Available for $2.99 for the Kindle and for iBooks on iOS.
On January 15, 1919 in Boston’s North End, a storage container holding around 2.3 million gallons of molasses ruptured, sending a 8-15 ft. wave of molasses shooting out into the streets at 35 mph. Twenty-one people died, many more were injured, and the property damage was severe. In an article in Scientific American, Ferris Jabr explains the science of the molasses flood, including why it was so deadly and destructive.
A wave of molasses does not behave like a wave of water. Molasses is a non-Newtonian fluid, which means that its viscosity depends on the forces applied to it, as measured by shear rate. Consider non-Newtonian fluids such as toothpaste, ketchup and whipped cream. In a stationary bottle, these fluids are thick and goopy and do not shift much if you tilt the container this way and that. When you squeeze or smack the bottle, however, applying stress and increasing the shear rate, the fluids suddenly flow. Because of this physical property, a wave of molasses is even more devastating than a typical tsunami. In 1919 the dense wall of syrup surging from its collapsed tank initially moved fast enough to sweep people up and demolish buildings, only to settle into a more gelatinous state that kept people trapped.
This could just be a Boston urban legend, but it’s said that on hot days in the North End, the sweet smell of molasses can be detected wafting through the air.
After running since 1944, the pitch drop experiment at Trinity College Dublin has finally yielded results: a drop has been caught falling on camera.
Pitch is an extremely viscous substance, about 2 million times more viscous than honey. Drops take 7-13 years to form and less than a second to fall. A similar experiment has been running at University of Queensland in Brisbane, Australia since 1927…their next drop is expected to fall sometime later this year.
Turning the Sun into a giant radio telescope through gravitational lensing will take some work, but it is possible.
An Italian space scientist, Claudio Maccone, believes that gravitational lensing could be used for something even more extraordinary: searching for radio signals from alien civilizations. Maccone wants to use the sun as a gravitational lens to make an extraordinarily sensitive radio telescope. He did not invent the idea, which he calls FOCAL, but he has studied it more deeply than anyone else. A radio telescope at a gravitational focal point of the sun would be incredibly sensitive. (Unlike an optical lens, a gravitational lens actually has many focal points that lie along a straight line, called a focal line; imagine a line running through an observer, the center of the lens, and the target.) For one particular frequency that has been proposed as a channel for interstellar communication, a telescope would amplify the signal by a factor of 1.3 quadrillion.
The Sun is so dense at its core that the average photon created by the fusion process takes more than 40,000 years to escape to the surface. !!!
The center of the Sun is extremely dense, and a photon can only travel a tiny distance before running into another hydrogen nucleus. It gets absorbed by that nucleus and the re-emitted in a random direction. If that direction is back towards the center of the Sun, the photon has lost ground! It will get re-absorbed, and then re-emitted, over and over, trillions of times.
This is from 1997, so that figure might have been revised a bit (anyone have updated numbers?) but still, that’s incredible. (via hacker news)
Some countries, the cool ones, put physicists and other scientists on their money. Here’s Niels Bohr on the Danish 500 kroner note:
Even the US sneaks onto the cool list with Ben Franklin on the $100.
Damn! Watch this railroad tanker car instantly implode:
I couldn’t find too much information on the source of this clip, but it appears to be part of a safety training video on the perils of improperly steam cleaning tanker cars. In the clip, the tanker car is filled with steam and the safety valves are disabled. The steam cools, then condenses, the pressure inside drops, and the pressure difference is big enough to crumple that huge railcar like a napkin.
Update: See also “sun kink”, when railroad tracks buckle in intense heat:
An explanation of the effect can be found here. (thx, will)
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