Vlatko Vedral and the demon machine

I've blogged about demons from time to time, and I've blogged about physicist Vlatko Vedral from time to time, too.

And now, two of my favorite topics are together at last, in an article about a demon-powered bead.

Masaki Sano, a physicist at the University of Tokyo, and his colleagues have demonstrated that a bead can be coaxed up a 'spiral staircase' without any energy being directly transferred to the bead to push it upwards. Instead, it is persuaded along its route by a series of judiciously timed decisions to change the height of the 'steps' around it, based on information about the bead's position. In this sense, "information is being converted to energy", says Sano....

Vlatko Vedral, a quantum physicist at the University of Oxford, UK, says that it will be interesting to see whether the technique can be used to drive nanomotors and artificial molecular machines. "I would also be excited to see whether something like this is already at work in nature," he says. "After all, you could say that all living systems are 'Maxwell's demons', trying to defy the tendency for order to turn back into randomness."

If you're a living system--and let's hope you are--as Cake would put it, Satan is your motor.

build your own time machine

Stephen Hawking says that time travel into the past is practically impossible. Fair enough. How about traveling into the future?

If we want to travel into the future, we just need to go fast. Really fast. And I think the only way we're ever likely to do that is by going into space. The fastest manned vehicle in history was Apollo 10. It reached 25,000mph. But to travel in time we'll have to go more than 2,000 times faster. And to do that we'd need a much bigger ship, a truly enormous machine. The ship would have to be big enough to carry a huge amount of fuel, enough to accelerate it to nearly the speed of light. Getting to just beneath the cosmic speed limit would require six whole years at full power...

After two years it would reach half-light speed and be far outside our solar system. Two years later it would be travelling at 90 per cent of the speed of light. Around 30 trillion miles away from Earth, and four years after launch, the ship would begin to travel in time. For every hour of time on the ship, two would pass on Earth. A similar situation to the spaceship that orbited the massive black hole.

After another two years of full thrust the ship would reach its top speed, 99 per cent of the speed of light. At this speed, a single day on board is a whole year of Earth time. Our ship would be truly flying into the future.

Hawking estimates that it'd take 80 years to reach the edge of the galaxy. But here's where this method of time travel loses out to a much more plausible (and probably much more affordable) option. Consider that during those 80 years, you'd age at a normal rate--unless, like in a lot of Sci-Fi-let's-travel-to-the-edge-of-the-universe flicks, you were somehow sleeping away the time in suspended animation.

And that's the key. After all, if your only goal is to wake up 150 years in the future without having aged, why travel anywhere? What we need is a Rip Van Winkle technology, not a monstrous spaceship, if we really want to travel in time. The trick isn't to go faster, but to slow down.

Vlatko Vedral decodes reality

According to Vlatko Vedral (who's been mentioned here before), the universe is a quantum computer.

Over the last two decades, a flourishing field of quantum information and computation has generated a wealth of experimental and theoretical tests of information processing at the quantum scale. Vedral is one of the luminaries in this field.

In Decoding Reality, Vedral argues that we should regard the entire universe as a gigantic quantum computer. Wacky as that may sound, it is backed up by hard science. The laws of physics show that it is not only possible for electrons to store and flip bits: it is mandatory. For more than a decade, quantum-information scientists have been working to determine just how the universe processes information at the most microscopic scale.

Combine this with Nick Bostrom's "simulation argument," and, like Hamlet, you start wondering which level you're on, and if there will be any continues when the game ends. (At least I think that's what Hamlet was on about.)

virtual reality gets really realistic

Nick Bostrom's "simulation argument" just got a little more plausible.

The computing power that is now available makes it feasible to simulate physical processes from the smallest scale upwards, rather than trying to approximate their overall effect.

For example, when computer scientist Jonathan Kaldor at Cornell University, Ithaca, New York, wanted to create virtual fabrics better those that had gone before he did something unthinkable just a few years ago. "We decided to start from the [individual] yarns. It sounds crazy but it actually works."

Knitting garments like socks and scarves from virtual wool modelled on real-world yarn gives results that stretch and deform realistically no matter how close up the view. The results could also be used with a haptic interface to provide the feel of fabric.

To add further realism, the team now plans to simulate the fuzz on the surface of each piece of yarn that adds friction between threads.

Click through and watch the video to see the improved physics in action.

I read it, but I don't get it

The title of this post is stolen from one of the best books any English teacher (or any secondary teacher, for that matter) can buy. I thought of Tovani's classic while attempting to read this paper [pdf], offered as "homework" by blog-neighbor Mark Olson. Here's a sample:

If either one of these functions, say θF/a , is influenced by some information that is free in the above sense (i.e., not a function of A’s choice of directions and events F-earlier than that choice),then there must be an an earliest (“infimum”) F-time t0 after which all such information is available to a. Since the non-free information is also available at t0, all these information bits, free and non-free, must have a value 0 or 1 to enter as arguments in the function θF/a . So we regard a’s response as having started at t0.

You can be the world's most competent reader--me--and still have no idea what you're reading, if you lack the requisite background knowledge.

symplectic camels and quantum uncertainty

I'll let the science writer explain a potential challenge to the Heisenberg Uncertainty Principle:

Maurice de Gosson at the University of Vienna in Austria thinks that the inability to pin a particle down is due to something called symplectic geometry, not quantum weirdness.

De Gosson realised that a theorem in symplectic geometry had parallels with the uncertainty principle. The concept is known as the symplectic camel after the biblical suggestion that it is easier for a camel to pass through the eye of a needle than for a rich man to get into heaven.

De Gosson imagined that a ball represents a cloud of possible positions for a quantum particle. He found that such a ball cannot be squeezed down to the size of one particle to fit through a hole in a plane, because its geometry resists this in some way. The inability to squeeze the ball is analogous to singling out one particle and measuring its position and momentum exactly. De Gosson reckons this geometrical resistance creates the uncertainty in measurement, not quantum fuzziness (Foundations of Physics, vol 39 p 194).

I just wanted to point out the word: symplectic. In my imagination, it is a super-adjective combining the meanings of sympathy and apoplexy.

Tolkien inspires true invisibility cloak?

The previous incarnation of an invisibility cloak--to stretch the term--worked only in the microwave spectrum. A new technology using gold rings in the visible spectrum, then, is big news:

The new cloak, which is just 10 micrometres in diameter, guides rays of light around an object inside and releases them on the other side. The light waves appear to have moved in a straight line, so the cloak – and any object inside – appear invisible.

The cloak was built by a team led by Igor Smolyaninov at the University of Maryland, and borrows some ideas from the first theoretical design for an invisibility cloak, published by Vladimir Shalaev from Purdue University, West Lafayette, Indiana, US, earlier this year.

Read the whole thing to see how it's done. Pretty limited, still, but it may mean that truly functional 3D invisiblizing could be mere decades away.

more habitable islands in the multiverse?

Cosmologists are trying to test the limits of the weak Anthropic Principle by tweaking some fundamental assumptions about physical laws, NewScientist reports:

It all comes down to numbers. Harnik argues that there will be countless more universes with myriad properties different from our own. By varying just one property, cosmologists have been too conservative. Harnik, Kribs and Perez decided to highlight this flaw in anthropic reasoning by taking a radical measure: they switched off the weak nuclear force, one of the four fundamental forces in nature. In practice, this means changing a multitude of parameters and constants simultaneously.

The weak force is responsible for the radioactive beta decay of atomic nuclei and is considered essential for a complex universe like ours. Take it away, and you might expect the "weakless" universe to be wildly different from our own.

Only Harnik, Kribs and Perez have discovered it isn't. They considered what would happen to crucial processes in the history of the universe - the forging of elements in the big bang, the powering of stars and supernovae explosions. By examining the equations that describe these processes, they made an astonishing discovery: the weakless universe is still capable of supporting observers....

It is not the only evidence to suggest that we need to broaden our horizons when it comes to testing the anthropic principle. In 2001, Anthony Aguirre of the University of California, Santa Cruz, found another island in the multiverse....

The crucial parameter that determines whether the big bang is hot or cold is the number of photons per baryon. In our universe it is about a billion. Aguirre wondered what would happen if it was in the range 0.1 to 100 - much, much cooler.

Aguirre's universe started off quite unlike our own (Physical Review D, vol 64, p 083508). After our hot big bang, the universe took tens of millions of years to cool to the point where matter could clump into stars. "But in the cold big bang universe, stars can begin to form within 100 years of the big bang," says Aguirre.

He even modelled an extreme cold big bang universe where the cosmological constant was 1017 times what it is in our universe. By rights, this strong repulsive force ought to fling matter apart, preventing the formation of galaxies. However, in the cold big bang universe, stars form so quickly that they are in place before this cosmological repulsion takes hold. "The stars then rush away from each other," says Aguirre. "It's a pretty dull universe with each star isolated in a vast ocean of space. Nevertheless, there is nothing to prevent such stars having planets and observers."

As computing power increases, expect to see more viable simulations of alternate universe formations. Also, expect to be sucked in by the eerie logic of Nick Bostrom's Simulation Argument. As I've summarized it, "If we grant that a sufficiently advanced civilization could create a workable simulation of existence, we have every right to suspect we inhabit that simulation."

herbertsmithite and string-net liquids

The most intriguing green crystal in the universe can't stop Superman, but it could be as debilitating as kryptonite to modern physics.

"Wen and Levin's theory is really beautiful stuff," says Michael Freedman, 1986 winner of the Fields medal, the highest prize in mathematics, and a quantum computing specialist at Microsoft Station Q at the University of California, Santa Barbara. "I admire their approach, which is to be suspicious of anything - electrons, photons, Maxwell's equations - that everyone else accepts as fundamental."

Other theories that try to explain the same phenomena abound, of course; Wen and Levin realise that the burden of proof is on them. It may not be far off. Their model predicts specific arrangements of atoms in the new state of matter, which they dub the "string-net liquid", and Joel Helton's group at MIT might have found it.

Helton was aware of Wen's work and decided to look for such materials. Trawling through geology journals, his team spotted a candidate - a dark green crystal that geologists stumbled across in the mountains of Chile in 1972. "The geologists named it after a mineralogist they really admired, Herbert Smith, labelled it and put it to one side," says team member Young Lee. "They didn't realise the potential herbertsmithite would have for physicists years later."

Herbertsmithite (pictured) is unusual because its electrons are arranged in a triangular lattice. Normally, electrons prefer to line up so that their spins are in the opposite direction to that of their immediate neighbours, but in a triangle this is impossible - there will always be neighbouring electrons spinning in the same direction. Wen and Levin's model shows that such a system would be a string-net liquid.

Although herbertsmithite exists in nature, the mineral contains impurities that disrupt any string-net signatures, says Lee. So Helton's team made a pure sample in the lab. "It was painstaking," says Lee. "It took us a full year to prepare it and another year to analyse it."

They were quite surprised with the results. You'll have to click through to find out why.

"Paradigm shift" is too twentieth century. Ready for a phase change?

thank you, I'll be here all week

Is it or isn't it a quantum computer? Yes.

He said all the evidence the company has indicates that the device is performing quantum computations, but he acknowledged there is some uncertainty.

Get it? Get it?


(Don't get it? Schrödinger and Heisenberg. Never mind.)

yes and no

The problem with string theory, says Lee Smolin, is that it's not falsifiable.

Smolin argues from the outset that viable hypotheses must lead to observable consequences by which they can be tested and judged. That is, they have to be falsifiable. Newton's theory of gravitation, for example, could later account for the orbit of Halley's Comet – not just those of the Moon and planets for which it was originally formulated. But string theory by its very nature does not allow for such probing, according to Smolin, and therefore it must be considered as an unprovable conjecture.

Or is it?

In 2006, string theorist Allan Adams of MIT in Cambridge, US, and others offered a more promising check. They showed that some particle collisions could reveal whether certain fundamental assumptions underlying string theory are wrong.

Now, another team has shown that the energies needed to reveal such effects are achievable at the LHC, which is being built in Geneva, Switzerland. The team was led by Jacques Distler of the University of Texas in Austin, US.

One of string theory's assumptions comes from Einstein's theory of relativity – that the speed of light is the same for all observers, a principle called Lorentz invariance.

This principle – and three others underlying string theory – determine how strongly particles called W bosons, which transmit the weak nuclear force, interact.

If these interactions are below the strength calculated by Distler's team, it would signal that one of the assumptions built into string theory is incorrect and that therefore string theory itself is wrong, the researchers say.

All we can do is wait and see.

negative refraction hits visible spectrum

The gee-whiz:

The race to build an exotic material with a negative refractive index for visible light has been won by a team of researchers in Germany. The demonstration could open the door to a new generation of optical devices such as superlenses able to see details finer then the wavelength of visible light.

The aw-shucks:

For now, Dolling is concentrating on studying the new effects rather than attempting to build devices such as superlenses. These applications are still a long way off, he told New Scientist.

NewScientist at 50: Roger Penrose describes reality

In his entry, Roger Penrose argues that a Platonic world of mathematical truths coexists with the world of molecules and molehills. Penrose's argument, in short [sub. req.]:

Our mathematical models of physical reality are far from complete, but they provide us with schemes that model reality with great precision - a precision enormously exceeding that of any description that is free of mathematics. There seems every reason to believe that these already remarkable schemes will be improved upon and that even more elegant and subtle pieces of mathematics will be found to mirror reality with even greater precision. Might mathematical entities inhabit their own world, the abstract Platonic world of mathematical forms? It is an idea that many mathematicians are comfortable with. In this scheme, the truths that mathematicians seek are, in a clear sense, already "there...." To a mathematical Platonist, it is not so absurd to seek an ultimate home for physical reality within Plato's world.

This is not acceptable to everyone. Many philosophers, and others, would argue that mathematics consists merely of idealised mental concepts, and, if the world of mathematics is to be regarded as arising ultimately from our minds, then we have reached a circularity: our minds arise from the functioning of our physical brains, and the very precise physical laws that underlie that functioning are grounded in the mathematics that requires our brains for its existence. My own position is to avoid this immediate paradox by allowing the Platonic mathematical world its own timeless and locationless existence, while allowing it to be accessible to us through mental activity. My viewpoint allows for three different kinds of reality: the physical, the mental and the Platonic-mathematical, with something (as yet) profoundly mysterious in the relations between the three.

What Penrose doesn't acknowledge is that some convergences are coincidences--and that mathematics can be entirely internally consistent, yet need not map onto any external reality, or are adaptable to entirely variable realities. (The gaping holes in the middle of math brought by Gödel go completely unmentioned.)

In other words, math would be an epiphenomenon: predictable, and predictive, but not on its own level of existence--like a literary character in the pages of a novel.

As a bonus, the article offers Nick Bostrom's simulation argument. If we grant that a sufficiently advanced civilization could create a workable simulation of existence, we have every right to suspect we inhabit that simulation.

so much for that

NewScientist's headline trumpets, "Working invisibility cloak created at last." The article, though, is a little more mundane:

To simplify the problem, Smith's cloak works in only two dimensions. It is about the size of a movie reel canister and consists of a series of concentric rings, each housing a set of simple electronic components that distort an electromagnetic field as it passes through....

"It's not perfect," says Leonhardt. "If you could see in the microwave region of the spectrum, the copper ring would not quite disappear. You'd see perhaps a shadow and some slight distortion where the copper ring ought to be."

The device has another important limitation – it works only at a single specific frequency of microwave. "How it might be possible to make a device that works over a range of frequencies is an open problem," says Leonhardt. But Smith now hopes to build a 3D structure that could hide an object completely from view.

So far, the technology works only in the microwave region of the spectrum. The problem with visible light is that it has a much smaller wavelength, meaning an optical metamaterial would have to be built on the nanoscale, which is beyond the limits of current nanotechnology. It, too, would only work at a specific frequency.

Boo-urns, NewScientist, for shattering our hopes and dashing our dreams.

Lee Smolin on the temporality of physical laws

The non-inciting part of the Pope's speech--the part that got less radio play--involved faith and reason in conflict and combination. Quoth Benedict, as noted by my brother:

Modern scientific reason quite simply has to accept the rational structure of matter and the correspondence between our spirit and the prevailing rational structures of nature as a given, on which its methodology has to be based.

Compare that with Lee Smolin, in the latest NewScientist [subs. req.]:

In science we aim for a picture of nature as it really is, unencumbered by any philosophical or theological prejudice. Some see the search for scientific truth as a search for an unchanging reality behind the ever-changing spectacle we observe with our senses. The ultimate prize in that search would be to grasp a law of nature - a part of a transcendent reality that governs all change, but itself never changes.

The idea of eternally true laws of nature is a beautiful vision, but is it really an escape from philosophy and theology? For, as philosophers have argued, we can test the predictions of a law of nature and see if they are verified or contradicted, but we can never prove a law must always be true. So if we believe a law of nature is eternally true, we are believing in something that logic and evidence cannot establish.

Of course, laws of nature are very useful, and we have in fact been able to discover good candidates for them. But to believe a law is useful and reliable is not the same thing as to believe it is eternally true. We could just as easily believe there is nothing but an infinite succession of approximate laws. Or that laws are generalisations about nature that are not unchanging, but change so slowly that until now we have imagined them as eternal.

These are disturbing thoughts for a theoretical physicist like myself. I chose to go into science because the search for eternal, transcendent laws of nature seemed a lofty goal. However, the possibility that laws evolve in time is one that recent developments in theoretical and experimental physics have forced me, and others, to consider....

Here is the question that keeps me awake these days: is there a way to represent the laws of physics mathematically that retains the notions of the present moment and the continual unfolding of time? And would this allow us - or even require us - to formulate laws that also evolve in time?...

It is not impossible to achieve time-bound laws in physics. There are logicians who have proposed alternative systems of logic that incorporate a notion of time unfolding. In these logics, what is true and false is assigned for a particular moment, not for all time. For a given moment some propositions are true, others false, but there remains an infinite list of propositions that are yet to become either true or false. Once a proposition is true or false, it remains so, but at each moment new propositions become decided. These are called intuitionalist logics and they underlie a branch of mathematics called topos theory.

Some of my colleagues have studied these logics as a model for physics. Fotini Markopoulou of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, has shown that aspects of space-time geometry can be described in terms of these logics. Chris Isham of Imperial College London and others propose to reformulate physics completely in terms of them.

Looking at biology, it seems there are advantages to what are, essentially, time-bound laws. Evolving laws might make computer systems similarly robust and less likely to do what the laws of natural selection, it seems, never do: crash. The universe, too, seems to function rather well, operating without glitches and fatal errors. Perhaps that's because natural selection is hard at work in the laws of nature.

I'd love to republish the whole thing, because it's hidden behind a subscriber-only firewall, but I'm too respectful of copyright. I'll poke around and see if anyone else has written about it, and link to their (more learned) opinions.

Added: Luboš Motl, for one, isn't very happy.

Lee Smolin promotes his cosmological natural selection. Just during the last month, five independent people have mentioned this issue in discussions with me or in their own articles; the list included famous names like L.S. or A.V. All of them are convinced that it is trivial to falsify Smolin's hypothesis and it has, in fact, been done immediately when Smolin proposed it.

A decade ago, Smolin had conjectured that the laws of our universe are optimized for black hole production because every new black hole is a new baby whose properties are similar to the parent universe but it is not quite identical because there is also a cosmological mutation going on. The most prolific universes - those who create many black holes - are going to dominate the ensemble of the universes. Lee Smolin has written a whole book whose content is isomorphic to this paragraph.

It is easy to see that if you change some parameters in our universe, for example if you reduce the hierarchy between the electroweak scale and the Planck scale, many more black holes will be created. The theory is dead. Trivially dead. Period. Why does Smolin revive this nonsense all the time, without having any new arguments or mechanisms? Does a lie become the truth when it is repeated 100 times?

superconducting magnesium diboride, phonons, and extra added bonus energy

Peter links to a website making preposterous, nearly impossible claims. I say "nearly impossible" because the accepted model of physics simply can't allow energy for nothing--but hope springs eternal.

On a more realistic front, room-temperature superconductivity, one of physics' Holy Grails, might be within reach in a decade or two. (Sorry, have to be a subscriber to read it all.) Magnesium diboride is the key.

Last year, [Warren] Pickett decided to go back to basics and re-examine the theory, inspired by an astonishing discovery reported in 2001 by Jun Akimitsu's team at Aoyama Gakuin University in Tokyo. Akimitsu and his colleagues were playing around with mixtures of titanium, magnesium and boron in an attempt to find a new superconductor. To their surprise, they stumbled across hints of superconductivity at 40 K....

The finding was scientific dynamite. Within two months of Akimitsu's announcement, 50 papers were published online as researchers rushed to study magnesium diboride for themselves....

Pickett realised that if he could identify what made magnesium diboride so special, other metal alloys might be found with even higher critical temperatures. To do this, he studied what affected the critical temperature in Bardeen, Cooper and Schrieffer's studies and then compared these factors to the properties of magnesium diboride.

According to their theory, the critical temperature depends on three things: the number of electrons available, the frequency at which the phonons vibrate, and the strength of the interaction or "coupling" between the phonons and electrons. Magnesium diboride's high transition temperature is due mostly to strong coupling, which is down to its chemical structure. It consists of layers of boron just one atom thick sandwiched between layers of magnesium atoms.... Each magnesium atom feeds two electrons into the boron layers, which means that there are abundant electrons in the structure.... [T]he electrons flow in the same layer as the boron atoms and set up large disturbances, which enhance the coupling between phonons and electrons as they sweep through the material. The upshot is that the electron-pairing still takes place at higher temperatures than expected.

Despite the strong interaction between phonons and electrons... only 3 per cent of phonons interact at all. "Impressive as it is, magnesium diboride is doing a poor job of making use of the available phonons," says Pickett. "If we could use most of the phonons, the critical temperature would increase all the way past room temperature...."

[H]e proposes involving more phonons by trying different combinations of elements. What's more, his blueprint gives researchers clues as to which elements would work best, rather than resorting to trial and error as they have done in the past. By doing this, his calculations show that it should be possible to find a material that superconducts at a searing 430 K...."

430 K is over 314 degrees Fahrenheit, an incredible temperature, hundreds of degrees (on any scale) hotter than present technology. Pickett, to his credit, hasn't made any unverifiable promises or formed a startup company to lure investors with dreams of glory. We'll just have to wait for the revolution.

violin subharmonics

Mix a musician with freaky talent and physicists with too much free time, and what do you get?

“Kimura makes a violin string vibrate in a totally new way. In physics we call this a driven and damped non-linear system, which we are particularly preoccupied with in our research,” Hanssen said. Driven and damped systems are, respectively, ones in which an outside force either stimulates or quashes a vibration. Nonlinear systems are ones in which there is no simple relation between a disturbance and the response to it.

Kimura said that if Hanssen’s team comes up with any answers, these may be useful to her, by suggesting yet new avenues to manipulate tones. “As an artist you are always searching for ways to expand the sound,” she said.

All she needs now is an amp that goes up to eleven.

'scuse me while I kiss the sky

To the literal-minded reader of Genesis 11, humanity's baffling mix of myriad languages arose out of hubris, as God punished ancient architects by sowing linguistic confusion. It worked for a time.

But God had better act again, and soon. In the ultimate act of mad science, physicists are working on a way to create a mini-universe [subs. req.].

Sakai and his team realised that a seemingly stable monopole in our universe is always teetering on the brink of expansion - needing just a nudge to start it inflating. Hurling mass onto the monopole - increasing its energy density - will push it over the edge, leading to runaway inflation (www.arxiv.org/gr-qc/0602084). "Our calculations show that, given enough energy, the monopole will inflate eternally," Sakai says.

This process could be triggered naturally. According to Sakai, if a monopole floating through space collided with another massive object it would gain the mass needed to trigger inflation. One candidate is a cosmic string - a kind of high-energy rip in space-time. Though we have yet to see one, cosmic strings may have been created as a by-product of the big bang.

But since we have no cosmic strings - and we'd like to remain in control of the project - Sakai suggests we might be able to trigger inflation by hurling particles onto a monopole in an accelerator. This would add mass, and thus energy, to the monopole, and make it blow up into an entirely new universe.

It would be an extraordinary achievement, of course, but what happens then? It's one thing to create a universe, but quite another to know where to keep it. After all, an eternally inflating universe might be expected to take up quite a bit of space - the cupboard under the stairs simply won't do.

Actually this wouldn't be a problem, Sakai says. For a start, the process warps space-time enormously, so that it is no longer the Euclidean space we are familiar with. This highly distorted space doesn't have the same geometry as normal space, so it's not as if the universe would blow up and engulf us....

The question is, would it be worth all the effort? Linde thinks so. "I sat down and really thought about why we should even care about creating a universe in the laboratory," Linde says. "We put energy into the baby universe to create it, but we can't get any energy out of it - we can't mine its resources." Once it's formed, he adds, its space and time - though growing - is entirely divorced from our own. "We can't jump into this tiny thing and visit it," says Linde. "We don't seem to be able to communicate with it at all."

In the end, Linde realised he had overlooked the obvious motivation: good old-fashioned megalomania. "Just imagine if it's true and there's even a small chance it really could work," he says. "In this perspective, each of us can become a god."

Woe unto us all.

the thrill of a quill

To be precise, a quill printer.

So the Palo Alto Research Centre in California (PARC), run by Xerox, has developed a new type of printer with tiny cantilever arms that flip between an ink reservoir and the paper, picking up and depositing a speck of ink powder or drop of liquid ink.

The cantilever arm is around 2 millimetres long and is flipped using electrostatic forces. The main stem of the arm is coated with Teflon, with a bare metal tip that is slit like a fountain-pen nib so that it picks up and deposits a few pico-litres of ink every time it flips.

(This is for you, bro.)

a loose thread in the fabric of the cosmos

Just when you think Brian Greene may be on to something, along come a couple of California researchers who think that maybe black holes aren't real, after all.

The audacious idea comes from George Chapline, a physicist at Lawrence Livermore National Laboratory in California, and Nobel laureate Robert Laughlin of Stanford University and their colleagues. Last week at the 22nd Pacific Coast Gravity Meeting in Santa Barbara, California, Chapline suggested that the objects that till now have been thought of as black holes could in fact be dead stars that form as a result of an obscure quantum phenomenon. These stars could explain both dark energy and dark matter....

Black hole expert Marek Abramowicz at Gothenburg University in Sweden agrees that the idea of dark energy stars is worth pursuing. "We really don't have proof that black holes exist," he says. "This is a very interesting alternative...."

Abramowicz says we know too little about dark energy and dark matter to judge Chapline and Laughlin's idea, but he is not dismissing it out of hand. "At the very least we can say the idea isn't impossible."

I wonder what Stephen Hawking thinks.