Entangled States

Macroscopic Entanglement

The mystery of avian navigation has confounded biologists for generations. It's well accepted that birds can "sense" the Earth's magnetic fields and that they use this "sense" to navigate their way across the surface of the earth.

But no one has been able to locate the center of the "sense" or figure out a mechanism by which the birds made use of it.

That is until just recently. There's a group of scientists that theorize that the birds are actually making use of quantum entanglement at the macroscopic level.

In brief:

"The system Vedral and co have studied is a model that describes how birds navigate using the Earth's magnetic field. The most recent thinking is that birds have molecules at the back of their eyes that are sensitive to both photons and the orientation of the Earth's magnetic field. When one of these molecules absorbs a photon, an electron pair is split and one of these electrons is transferred to another part of the molecule to another. These electrons then form a 'radical pair' that are entangled.

In the absence of a magnetic field, this pair would recombine to form the original molecular state. But the Earth's magnetic field can flip the spin of one of these electrons allowing them to recombine in a different way and leaving the molecule in an alternative chemical state that the bird can sense. The result is that bird 'sees' the Earth's magnetic field as it flies.

This raises an interesting question: how long does this entangled state last?

Vedral and co have done the numbers and say it lasts for at least 100 microseconds. That's an extraordinary figure. The best humans have measured is 80 microseconds for so-called electron spin relaxation in C60 buckyballs."

Read the full article here.

Besides being way cool if true, this system would represent a macroscopic manifestation of entanglement. For those who are trying to find the effective limits of this uniquely quantum mechanical phenomenon, this is might likely call for some re-tuning of the models.

Yay for bird-brains!

US cities may have to be bulldozed in order to survive - Telegraph

There's been some talk over the past week of whether or not it makes sense to proactively shrink the size of American cities that are no longer economically sustainable.

There's an interesting article on the Telegraph's site that discusses the possibility of flattening a large part of Flint Michigan as a test case.

It features Dan Kildee who's been asked to come up with a plan for Flint that might be extended to at least another 50 cities in the US that are in the same situation.

Interesting point made in the article:

"But Mr Kildee, who has lived [in Flint] nearly all his life, said he had first to overcome a deeply ingrained American cultural mindset that 'big is good' and that cities should sprawl – Flint covers 34 square miles.

He said: 'The obsession with growth is sadly a very American thing. Across the US, there's an assumption that all development is good, that if communities are growing they are successful. If they're shrinking, they're failing.'

But some Flint dustcarts are collecting just one rubbish bag a week, roads are decaying, police are very understaffed and there were simply too few people to pay for services, he said.

If the city didn't downsize it will eventually go bankrupt, he added."

Read the full article here.

The issue isn't growth anymore, it's sustainability. Cities need to become sustainable in terms of economics, energy, supply chains, etc.

I write this only a few minutes away from large cities in Arizona that were created out of the desert for the sole reason that land was cheap there. There's no real economic reason they should exist.

And they're slowly falling down now too.

This is going to be a very difficult time for the outer-ring exurbs.

String theory and super-fluiditiy

Saw this today. If for no other reason, it's worth reading the highlighted portion below... because you'll wish you'd thought to say it.

"'Despite formidable odds, condensed matter physicists have made a breakthrough most thought impossible — finding a practical use for string theory. The initial breakthrough was made by physicist and cosmologist Juan Maldacena. His theory states that the known universe is only a 2D construct in anti-de-Sitter space, projected into 3 dimensions. This theory manages to model black holes and quantum theory congruently, a feat that has eluded scientists for decades; but it fails to correspond to the shape of space-time in the known universe. However, it does predict thermodynamic properties of black holes, including higher-dimensional viscosity — the equations for which elegantly and almost exactly calculate the behavior of quark-gluon plasma and other superfluids. According to Jan Zaanen at the University of Leiden, 'The theory is calculating precisely what we are seeing in experiments.' Unfortunately, the correspondence cannot prove or disprove string theory, although it is a positive step.'"

Read the full article here.

Of course, all that being said, there's no report about whether the developed theory was able to discriminate between to competing claims...

Where are they? Another solution to Fermi's paradox.

Fermi's paradox is the most frequent objection to the idea that there exists intelligent extra-terrestial life.

Now there's appears to be a new solution to the paradox - perhaps the implicit assumption that populations of sentient beings will grow continuously and exponentially is wrong.

Two scientists at Penn State University suggest that:

"The problem is that this kind of growth may not be possible and they look at Earth as an example. For any expansion to be sustainable, the growth in resource consumption cannot exceed the growth in resource production. And since Earth's resources are finite, it has a finite mass and receives solar radiation at a constant rate, human civilization cannot sustain an indefinite, exponential growth.

So we'll have trouble colonising the galaxy, if we ever decide that's necessary. At the very least, the spread of our civilisation will not be exponential, if it is possible at all.

Haqq-Misra and Baum say that this argument means that any extraterrestrial civilisation must be similarly constrained."

Read the full article here.

Interesting idea. Certainly we can see how difficult it is to create sustainability in social organizations. Church congregations for instance seem to have at least four inherent population plateaus - at least in the Episcopal Church - according to research Arlen Rothage did back in the 70's. It's possible to overcome the plateau limit, but it takes a great deal of work.

Perhaps this same phenomenon is at work in the galaxy. Planetary civilizations might be limited in the degree that they can expand by technology and/or lifespan issues. Perhaps there are plateaus at the planetary, the planetary system level and at the interstellar level. Which would make sense - each scale involves multiple order of magnitudes scale changes.

Hmmm.

I wonder if there's a ubiquity or fractal distribution law at work? I've wondered that for some time about whether that exists for congregation sizes. We know that it exists for city sizes. Seems like the same basic resource and scaling plateaus that exist here on earth would exist in the galaxy as well.

Room Temperature Entanglement...

Entanglement, the physical phenomenon which can only be explained quantum mechanically at this point, is mostly observed in very simple systems, at relatively low energies and over small distances.

But there's news today that we may have found evidence of entanglement occurring in much more complicated system - and even in photo-synthesis processes.

From the Physics ArXiv blog:

"[A] new, more robust face of entanglement is beginning to emerge from other types of experiment. For example, physicists have recently found the signature of entanglement in the thermal states of bulk materials at low temperatures. This has huge implications for biological systems: if entanglement is more robust than we thought, what role might it play in living things?

Now we're beginning to find out. In the first rigorous quantification of entanglement in a biological system, an answer is beginning to emerge. Researchers from various institutions in Berkeley California have show that molecules taking part in photosynthesis can remain entangled even at ordinary atmospheric temperatures.

The evidence comes from detailed study of light sensitive molecules called chromophore that harvest light in photosynthesis. "

Read the full article here.

How cool is that? Normal plant life, if this is right, is only able to harvest the energy of the Sun via this fundamentally non-deterministic process.

It may exist over short distances, but like quantum tunneling which makes solid state electronics possible, it has huge implications at the human scale.

Neat!

The Milky Way rising

Such a great video from a Texas star party:

Galactic Center of Milky Way Rises over Texas Star Party from William Castleman on Vimeo.

Don't you wish you had the patience to do something like this?

Standard Candle upgrade

Almost every measurement in cosmology ultimately depends on using a "standard candle" to determine distance, which in turn is used to determine every other observable quantity - age, mass, speed, etc.

A standard candle is just what it sounds like. A light source with a known brilliance. A cosmological standard candle is, ideally, a luminous object that can be seen over great distances, is somewhat common, and is, well, standard. In other words each object either has the same brilliance at a given distance, or there exists an algorithm for figuring out it out as a function of mass or size or something else.

For a long time astronomers searched for such an object that would be bright enough close up that it could be seen all the way across the universe. (Which is not all trivial - galaxies aren't generally that bright...) A couple of decades ago scientists finally realized that a specific sort of super nova (Type Ia) were all created by the same mechanism - the explosion of a white dwarf that has exceeded the Chandrasekhar limit of 1.4 solar masses. (No degenerate object can grow larger than that mass - the electroweak forces can't sustain the pressures beyond that.) Which means we can calculate exactly how much energy is present in the explosive event. Which means we know how bright it is...

Which means determining distance is merely then a matter of measuring how bright the explosion is when it's observed from Earth and then using the inverse square law to figure out how far away it is.

Voila! Standard Candle distance! Just what we need! And because the object is a super-nova, it's so intrinsically brilliant that it can be seen across the Universe.

That's why this news is a big deal:

"The new brightness-ratio correction appears to hold no matter what the supernova's age or metallicity (mix of elements), its type of host galaxy, or how much it has been dimmed by intervening dust.

Using classic methods, which are based on a supernova's color and the shape of its light curve - the time it takes to reach maximum brightness and then fade away - the distance to Type Ia supernovae can be measured with a typical uncertainty of 8 to 10 percent. But obtaining a light curve takes up to two months of high-precision observations. The new method provides better correction with a single night's full spectrum, which can be scheduled based on a much less precise light curve."

Read the full article here.

So, we can much more efficiently grab the data, and ultimately get much more accurate numbers out of it.

It was the data from these super-novas that led to the discovery that the Universe's expansion was, to everyone's massive surprise, accelerating rather than slowing down. Which we guess is being caused by the mysterious Dark Energy. Which we don't understand really at all. But which has to be there because of the observations based on these standard candle measurements.

Which is why this could be so important. Maybe we'll get a few more important clues about the explosive acceleration that goes against everything we thought we knew about gravity. Which means maybe we'll understand gravity better. Which means we'll be able to do some new cool things eventually.

Which should lead to new discoveries as exciting as this one.

Which is why science is such a blast!

(Pun sort of intended...)

Locality vs Non-Locality; a way to test?

The point of quantum entanglement as a paradigm breaking experiment is that the phenomenon indicates that reality is, in a fundamental way, not properly described in classical terms. Entanglement is a way of creating correlated states of being in simple systems that allow (in principle) instant communication. You change one part of the system, the other part instantly responds. The key-word is "instantly". Classical physics (which includes relativity) says that instant communication is disallowed because no information can travel faster than the speed of light. (I'm simplifying here, but hopefully you get the basic idea.)

It turns out from some work done a couple of decades or two ago that there is a limit to which the size of the correlations that underlie entanglement can grow. These were called "local" correlations because they couldn't grow larger.

And now then some work done showed there did exist some special sorts of correlations which might grow larger than that limit, but only in special circumstances. Such correlations were called non-local and even post-quantum by the people who wrote out the theory behind them.

There's news today of a way to possibly test these theories:

"To demonstrate that post-quantum correlations cannot exist in nature, Brunner and Skrzypczyk developed a protocol for deterministically distilling nonlocality in post-quantum states. That is, the technique refines weakly nonlocal states into states with greater nonlocality. In this context, ‘distillation’ can also be thought of as ‘purifying,’ ‘amplifying,’ or ‘maximizing’ the nonlocality of post-quantum correlations. Since nonlocal correlations are more useful if they are stronger, maximizing nonlocality has significant implications for quantum information protocols. The physicists’ protocol works specifically with ‘correlated nonlocal boxes,’ which are a particular class of post-quantum boxes.

Brunner and Skrzypczyk’s distillation protocol builds on a recent breakthrough by another team (Forster et al.), who presented the first nonlocality distillation protocol just a few months ago. However, the Forster protocol can distill correlated nonlocal boxes only up to a certain point, violating a Bell inequality called the Clauser-Horne-Shimony-Holt (CHSH) inequality only up to CHSH = 3. While this value is greater than Tsirelson’s bound of 2.82, it does not reach the bound of 3.26, which marks the point at which communication complexity becomes trivial.

Taking a step forward, Brunner and Skrzypczyk’s protocol can distill nonlocality all the way up to the maximum nonlocality of the Popescu-Rohrlich box, which is 4. In passing the 3.26 bound of triviality, they show that these post-quantum correlated nonlocal boxes do indeed collapse communication complexity."

Read the full article here.

The article will explain more efficiently than I could about what the implications of non-locality of 3-4 would indicate.

The upshot is that this would give us a robust handle on the scales in which quantum phenomenon dominate (and why) and where classical physics dominates. It doesn't unify the two, but giving a limit would actually lead to a deeper insight on just what the problem is that occurs when we try to do that. It's also of critical importance in the area of quantum computing but I'm not nearly as interested in that so I'll leave that as an exercise for the reader.. grin.

So read the article and enjoy.

(I was discussing something of this nature in a recent talk I gave. I've got to get around to posting the audio.)

Terry Eagleton: Reason, Faith and Revolution

Stanley Fish, writing on his blog "God Talk" over on the New York Times website has a lovely essay discussing a new book by Terry Eagleton. The book deals with the dual roles of Faith and Science in contemporary society, and apparently takes on critics of religious thought like Christopher Hitchens directly.

"[T]he fact that religion and theology cannot provide a technology for explaining how the material world works should not be held against them, either, for that is not what they do. When Christopher Hitchens declares that given the emergence of ‘the telescope and the microscope’ religion ‘no longer offers an explanation of anything important,’ Eagleton replies, ‘But Christianity was never meant to be an explanation of anything in the first place. It’s rather like saying that thanks to the electric toaster we can forget about Chekhov.’

Eagleton likes this turn of speech, and he has recourse to it often when making the same point: ‘[B]elieving that religion is a botched attempt to explain the world . . . is like seeing ballet as a botched attempt to run for a bus.’ Running for a bus is a focused empirical act and the steps you take are instrumental to its end. The positions one assumes in ballet have no such end; they are after something else, and that something doesn’t yield to the usual forms of measurement. Religion, Eagleton is saying, is like ballet (and Chekhov); it’s after something else.

After what? Eagleton, of course, does not tell us, except in the most general terms: ‘The coming kingdom of God, a condition of justice, fellowship, and self-fulfillment far beyond anything that might normally be considered possible or even desirable in the more well-heeled quarters of Oxford and Washington.’ Such a condition would not be desirable in Oxford and Washington because, according to Eagleton, the inhabitants of those places are complacently in bondage to the false idols of wealth, power and progress. That is, they feel little of the tragedy and pain of the human condition, but instead ‘adopt some bright-eyed superstition such as the dream of untrammeled human progress’ and put their baseless ‘trust in the efficacy of a spot of social engineering here and a dose of liberal enlightenment there.’"

Read the full article here.

Not having read the book, but intuiting from Fish, it appears that Eagleton's criticism of scientism is that it has an inadequate anthropology. (To borrow a turn of phrase from Paul Zahl.)

The end of Fish's essay though warns that Eagleton's rhetoric becomes increasingly angrier as the book progresses. Fish thinks it's because of Eagleton's frustration with the simplistic thinking of those arguing for scientism.

But, either way, the book might well be worth the read.d I'm putting it on my to-read list. Hopefully I can get to it some time this summer.

Thanks to Prof. Hsieh for the pointer.

Tweaking General Relativity to explain dark matter

The observation that the Standard Model of particle physics works really well in explaining most of what we see in our present experience, and yet is incapable as yet of explaining, much less predicting the experimental evidence of large scale deviations from gravitational predictions of the modern universe is hardly unremarked upon. The anomalous gravitational effects seen in galactic rotation curves and in the unexplained apparent change in gravity at great look-back distance is today explained by invoking Dark Matter and/or Dark Energy. Modern models that include dark matter and energy generally calculate that the normal matter that you and I are made of represents less than 10 percent, perhaps only 1 percent of the total gravitational matter in the Universe.

It's pretty disconcerting that the model which does so well in explaining what we can "see" does so badly for the vast majority of everything else. Either we've just gotten lucky, or there's something wrong with the model, or with the observations.

Lots of folks have played around with the Standard Model trying to make it more sophisticated. That's primarily what String Theory is all about. But there are some who want to leave the Standard Model as is, and who would rather look again at the anomalous gravitational observations with the idea that perhaps we'd be better off messing around with gravity theory instead.

That might not be such a terrible thing. Einstein's theory is already known to fail in certain high-energy regimes, and it has never yet been successfully made to interact with quantum theory.

What if we tried to tune the gravitational model by introducing some variable parameters which could then be tweaked to make gravitation predict what we observe without having to invent dark matter and dark energy?

Jose Cembranos is trying to do just that. An article on Physics.org reports on what Cembranos is calling the R2 model of gravitation:

"The model that Cembranos developed also allows you to tune the parameters of the system in order to explain dark matter. ‘I wanted to focus on the dark matter issue,’ he says, ‘because dark matter seems a little more straightforward. All you need to do is introduce more stuff into the model. We can do this with R2 gravity.’

Cembranos points out that while R2 gravity is an interesting approach to the problem, it doesn’t hold all the answers. ‘Many people have used different modifications of gravity in order to explain dark matter and even dark energy,’ he says. ‘However, usually these explanations end up being worse than Einstein gravity. Einstein gravity clearly has problems, but nearly all the other explanations are worse.’

What makes the model studied by Cembranos more promising, he insists, is that using the R2 term isn’t worse than Einstein’s gravity theory. ‘It’s not any better, but it’s also not any worse. It’s more or less the same, but a little more complicated.’"

Read the full article here.

What I find so interesting about this attempt is that it is very similar to what Plank did back in the 19th century to find a solution to the UV disaster in the black-body radiation curve. Plank introduced a tunable parameter that he called "h" (now called the Plank constant), and worked out its magnitude by fitting the black-body radiation curve to the spectrum that would be created by a simple harmonic oscillator limited with an "h" sized granularity.

That worked well so well that we now have an entire regime of physics based on Plank's work (as explained interestingly enough by Einstein in his work on the Photo-electric effect).

Perhaps here's another go that will have the same sorts of payoff?