The naturalness of altruism

September 19, 2016

screenshot-from-2016-09-19-110456

Our culture tends to assume that selfishness is natural, while altrusim requires an explanation. But why?

This question sprang to my mind the other day, while I was reading John Brashaw’s “In Defense of Dogs” (a book I am enjoying greatly – but that’s a different topic). I noticed a statement, made in passing, that whereas biologists do not feel the need to explain altruism in animals when it is directed towards members of the individual’s family, when this is not the case it always calls for an explanation. I get the impression that this is quite a well-established and reasonable view: when an individual helps a member of its family to survive, it is aiding the propagation of some of its genes – half when we help our offspring, one quarter when we help a sibling, one eighth when we help a first cousin, and so on. In contrast, helping a completely unrelated individual does not help the helper’s genes to propagate.

But then I thought: what if the other individual is of the same species? It does not help any of your genes, but that individual shares the same genome – the genome of your species – so you are helping your genome, and therefore your species, to survive. It would be reasonable to expect that species may have evolved whose evolutionary strategy includes altruism towards individuals of the same species, which would have given that species a competitive advantage against other species. This seems to me quite reasonable. But if we start to think that way, then we have to ask: what about helping individuals of other species? All species on Earth share the use of DNA as the gene-encoding substrate, so species that ehlp other species are contributing to the survival of DNA-based life. In fact, when you think of it, it is evident that all life on Earth is cooperating on a global scale, e.g. the plants capture CO2 and release oxygen that we breathe. While DNA-based lifeforms are not in direct competition with other forms of life, they may have been in the past, and in any case the DNA-based living Earth is always competing with the alternative, dead Earth. So again, if different species had not helped each other out perhaps there would be no life on Earth. 

So I think a more reasonable approach is to consider that there is a hierarchy of levels of organisation, and at every level cooperation is essential to make the whole possible (see figure). There are even some intermediate levels, for example oxygen-breathing lifeforms helped each other in competition with sulfur-based ones, for example. So although when you look at the nitty-gritty of individual interactions between individuals there seems to be a lot of competition going round, I think the big story of life on Earth is one of cooperation.

I think this part of a more general theme: in life, in society, and even at the microscopic level in the interactions between myriads of atoms or electrons inside materials, cooperation leads to behaviours that can reinforce themselves and survive, while pure competition leads to and “averaging out to zero”. So what is natural is coopertation and leads to what we observe -be it life on Earth or the magnetic field of a nedymium magnet. 

It is also, incidentally, a nicer way to look at the world than the victorian cut-throat tinge with which natural evolution is often described.

 


Curiosity

May 29, 2016

note290516_01.jpgWe are curious because curiosity gave our ancestors an evolutionary advantage: curious people knew where there were dangers, where to find food, where to find shelter. A curious person held a branch on fire rather than running away from it – not because she or he guessed it could come useful for cooking, for heating, or as a weapon or a source of energy –  but because they were intensely curious about it. It’s our most useful instinct.

Curiosity-led scientific research is the collective embodiment of human curiosity. It is helping us to survive and develop as a species. The moment we stop doing it will be the beginning of the end for our species.

We must fight to enshrine social support for curiosity-driven research. That’s research we do because we want to know, not because we want to achieve something. That’s the type of research that will save our civilisation from global warming, from hurtling meteorites, from dangerous microbes – from everything that, without our curiosity, we would never even have known about.


Superconductivity in the Hubbard model: an exact solution

June 15, 2010

If you read our article on strong correlations, you may remember that we still do not have an exact solution the Hubbard model in more than one dimension.You might also recall how important it was to learn something definite about superconductivity in this model. Now Raghu, Kivelson and Scalapino have published a paper proposing a way to obtain the superconducting phase diagram of this model in the weak-coupling limit:

S. Raghu, S. A. Kivelson, and D. J. Scalapino,
“Superconductivity in the repulsive Hubbard model: An asymptotically exact weak-coupling solution”,
Phys. Rev. B 81, 224505 (2010)
DOI: 10.1103/PhysRevB.81.224505

Follow the link for a synopsis of the above article in Physics.

Superconductivity in the repulsive Hubbard model: An asymptotically exact weak-coupling solution

Superconductivity in the repulsive Hubbard model: An asymptotically exact weak-coupling solution


Are high-energy physicists about to give us yet another probe?

October 17, 2009

In some recent posts I have highlighted the fact that some of the cutting-edge research in high-energy physics (HEP) is providing us with novel form of condensed matter – in particular, the quark-gluon plasma. This type of interaction between (or merging of) condensed matter and high-energy physics is new, since in the past HEP looked at process involving a few particles at a time, i.e. it was not concerned with collective states of matter or with phase diagrams.

On the other hand, there is a different short of interaction between HEP and condensed matter physics that goes a long way back, namely we owe to high-energy physicists some of the most powerful probes available of condensed matter systems. For example, the most advanced X-ray and neutron sources are based on particle accelerators (e.g. the electron and proton synchrotrons employed by Diamond and ISIS, respectively, here on the Harwell campus). Such machines ride on the back of advances in technology that were spurred by research at the frontier of particle physics some decades ago.

Now Andreas Ipp and Christoph Keitel propose that a new probe of matter may be provided by the quark-gluon itself:

Ipp, A., Keitel, C.H. & Evers, J., 2009. Yoctosecond Photon Pulses from Quark-Gluon Plasmas. Physical Review Letters, 103(15), 152301-4.

For a short summary see

Physics – The shortest known photon pulses.

The article argues that ultra-short pulses of light are emitted by the quark-gluon plasma formed in heavy-ion collisions and propose it as a probe of ultra-fast processes, such as those taking place inside the nucleus. The pulses are ~ 1 Yoctosecond = 1E-24 seconds in duration (look it up on Wikipedia). This corresponds to approximately 4 GeV. The question I ask is: what about condensed matter? Could this be useful there, too?

While all condensed matter processes are much less energetic than that, the energy of the probe need not be the energy of the excitation being probed – the energy of the probe just limits the resolution (the energy of the excitation being probed is the energy change of the photons in the pulse as they go through the sample). In that sense these ultra-short, high-energy pulses could be useful to probe excitations at much lower energies (e.g. ~ 10 meV, which is relevant for example for magnetic excitations in superconductors) but with potentially much more resolution than can be currently achieved.

The question is: are our current probes limited by their resolution? After all, what could we possibly learn that would be relevant to understand, say, a superconductor, that happens on the yoctosecond timescale? I’d love to know what people think about this.

One final though: the Yoctosecond pulses are obtained because a ys is the typical lifetime of a quark-gluon plasma (QGP). This raises the following difficulty, from the point of view of regarding the QGP itself as a condensed system and an object of study: if it only lasts for a ys, we are going to need even faster pulses to study its dynamics. In other words, if we regard the QGP as a condensed matter system, it is going to be really hard to invent the equivalents of neutron and X-ray scattering for this system. Perhaps we could use photons created in one QGP to probe another one…?


Are robots the next condensed matter?

September 23, 2009
Modular robots on the march... Is this the next condensed matter?

Modular robots on the march... Is this the next condensed matter?

Because condensed matter deals with concepts as fundamental as as scale invariance and broken symmetry, it is sometimes hard to predict where the next big condensed matter physics problem will turn up. For example (continuing from my latest post) who would have guessed twenty years ago that atomic physicists and high-energy physicists would today be furnishing some of the most interesting examples of strongly correlated matter? So it is interesting to be wild and speculate where the next big realm of condensed matter physics may lay. (After all, wild speculation is one of the things a blog may be useful for.)

In this spirit, I dare suggesting a look at modular reconfigurable robotics: robots made up of many individual, but interacting, identical elements. There are a number of groups around the world working on it. At the time of writing, there is a fairly detailed overview of the field on Wikipedia.

The Wikipedia article list a number of challenges for the future. It starts with the following (I quote):

Demonstration of a system with >1000 units. Physical demonstration of such a system will inevitably require rethinking key hardware and algorithmic issues, as well as handling noise and error.

A way to phrase this problem is to say that we want a large assembly of robots to behave like a condensed matter system, where a very large collection of individual, interacting elements (e.g. all the individual atoms in a magnetic material) conspire to produce a collective behaviour (e.g. ferromagnetism) in spit of the presence of errors and imperfections (e.g. impurities, missing atoms at indivudal lattice sites, and so on). So in some sense this problem of modular reconfigurable robotics has already been solved by Nature in condensed matter systems. Thus some important problems in modular reconfigurable robotics might be solved by looking to condensed matter for inspiration (e.g. find the conditions to achieve in the robots the equivalent of generalised rigidity).

Indeed researchers in that field are already having to draw on some elementary condensed matter concepts. See, for example, the PARC Modular Robotics website: the section on the Proteo project even has a good old-fashioned discussion of close packing structures.

Conversely, and perhaps even more interestingly (at least from a condensed matter theorist’s point of view) the robots could be used to realize new states of classical condensed matter – just as novel forms of quantum condensed matter are currently being created through chemical synthesis and in ultra-cold atom labs. Interestingly, the individual building blocks in the case of robots can be a lot more complex than in any form of condensed matter we currently know of e.g. the rules governing element-element interactions may be very complicated – for example, the interactions could be time-dependent or depend on the history of previous interactions for each individual particle (i.e. each individual robot module). It will be interesting to see whether such complexity of the individual particles will find a manifestation at the collective (macro) level or rather we will find that the beahviour of the whole always obeys simpler, emergent organisational principles. The latter is the case of, for example, a human crowd – though the interactions between individual components of a human crowd are in fact simple, while in the case of robots we might engineer them to be very complex.


John Hubbard’s challenge 45 years on

September 22, 2009

A very brief Highlight feature we wrote some time ago on the complementarity between condensed matter and cold-atom experiments has now appeared on the ISIS website:

* J Quintanilla, C Hooley, ST Carr, JJ Betouras, VL Campo Jr and K Capelle, “John Hubbard’s challenge 45 years on”.


Strong correlations in ultra-cold atom gases and at the RHIC – the string connection

September 17, 2009

You may remember a brief mention of Brookhaven’s Relativistic Heavy Ion Collider (RHIC) in our article on strong correlations of a couple of months ago. This month Physics World carries another article, by Barbara Jacak, that discusses that type of strongly-correlated quantum matter in a lot more detail. The new article explains how string theory can be used to connect the experiments at RHIC to others carried out on another type of strongly-correlated system: ultra-cold atomic gases. Well worth reading:
http://physicsworld.com/cws/article/indepth/40224

PS: there was also a much more technical article on strongly interacting matter (as the quark-gluon soup is now known) in Rev. Mods. Phys. a few months ago:

Colloquium: Phase diagram of strongly interacting matter
P. Braun-Munzinger and J. Wambach, Rev. Mod. Phys. 81, 1031 (2009)
http://dx.doi.org/10.1103/RevModPhys.81.1031