Hernán Alejandro Makse

Professor of Physics
Levich Institute and
Physics Department
City College of New York
Steinman Hall, T1M-12
140th Street and Convent Avenue
New York, NY 10031-9198
(212) 650-6847, (212) 650-6835 (fax)
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This is the lab of Hernán Makse at the Levich Institute and Department of Physics of City College of New York in New York City. Our group consists of graduate students Ping Wang, Kun Wang, Chris Briscoe, Yuliang Jin from the Physics Department, and postdocs Hernán Diego Rozenfeld, Diego Rybski and Lazaros Gallos.

Science-wise, we focus on the study of jammed matter, spanning from colloidal suspensions, dense emulsions to granular materials and glasses in search of unifying theoretical frameworks. We explore this variety of out of equilibrium systems in terms of their behavior as they experience structural arrest or jamming. The group focuses on the theoretical and computational approaches in parallel with the experiments, creating a productive research environment. We are also interested in the theoretical understanding of complexity. We are working towards the development of new arquitectural laws for complex networks, from biological systems, to the Internet, the web, to social networks.

For the latest research, see the presentations on jamming in granular matter, colloids and emulsions, random close packing (RCP), fractal complex networks, elasticity of granular matter, and urban economics. To download data and computer codes ranging from MD of granular matter, to fractal analysis of complex networks and cities, to experimental data on colloids and glasses, to generating sequences with long-range correlations visit SOFTWARE AND DATA.

We are currently hiring a postdoc in Complex Networks or Jammed Matter. Please send us your curriculum if interested.

Science Highlights

  • Best Connected Individuals May Not Be the Most Influential Spreaders in Social Networks

    . Who are the best spreaders of information in a social network? The answer may surprise you. See paper in pdf or the cond-mat version. Press releases: Technology review, Fast company, Science for SEO, Emedia.

    Not that it matters anyway, like Moorla would say in the NeverEnding Story.... Here is the excerpt:

    Atreju - Are you Moorla, the ancient one?
    Moorla - ~yawns~ Not that it matters. But yes.
    Atreju - Please help me Moorla. Do you recognize this?
    Moorla - Well, we haven't seen the Orion in a long time.
    Atreju - We? Is there someone else here too?
    Moorla - We haven't spoken to anyone else for thousands of years so we started talking to ourselves. Ah..ah...CHOO! ~sneezes~
    Atreju - Moorla! I bring terrible news. Did you know that the Empress is very ill?
    Moorla - Not that it matters, but yes. Actually we don't care.
    Atreju - If I don't save her she'll die! There's a terrible Nothing sweeping over the land. Don't you care about that?
    Moorla - We don't even care whether or not we care. Ah..ah...
    Atreju - Do you have a cold?
    Moorla - No. We're allergic to you. ACHOO!
    Atreju - You know how I can help the Empress, don't you?
    Moorla - Not that it matters but yes.
    Atreju - If you don't tell me and the Nothing keeps coming, you'll die too, both of you!
    Moorla - Die? That at least would be something. Ah...ah...oh....mmmmm.
    Atreju - Please help me. You said you knew the answer.
    Moorla - ACHOO! ~sneezes~ We're tired of sneezing, go away! Nothing matters
    Atreju - That's not true. If it didn't really matter to you, you could tell me.
    Moorla - Ha, ha, ha clever boy.
    Atreju - Tell me please!
    Moorla - We don't know but you can ask the Southern Oracle.
    Atreju - How can I get there?
    Moorla - You can't. It's 10,000 miles away.
    Atreju - But that's so far.
    Moorla - That's right. Forget it. Goodbye.

  • A first-order phase transition defines the random close packing of hard spheres. This is an attempt to define RCP using the thermodynamic framework of phase transitions. See paper.

  • We are learning how to make fractal babies: We investigate the network of human cell differentiation from the fertilized egg up to a crying baby. See paper which is appearing in PNAS soon.

  • Zipf's Law for once and for all.

    The City Clustering Algorithm, CCA, allows for a test of Zipf's law for cities of all sizes. We find (ta,tan,ta,tan..) that Zipf's law is surprisingly valid upto small cities of a few hundred inhabitants. This work is in collaboration with Xavier Gabaix from the Stern School in NYU and opens new avenues for theoretical work. See our recent paper on Zipf's law for all cities. Submitted to American Economic Review. Below is an image of all the population clusters identified by the CCA in the USA.

  • Recent work on statistical patterns in human communication and growth of cities.

    We find scaling laws in human communication patterns. See PNAS paper .
    Another recent PNAS paper presents a new way to define cities based on clustering algorithms from percolation theory. We find that the growth rate of cities and its standard deviation follow (surprise, surprise..) power-laws with the city size, in contradiction to Gibrat's law.

  • Renormalization Group analysis in fractal complex networks

    The small world-fractal transition and information flow. See recent paper in Phys. Rev. Lett.

  • Work on random close packings.

    Paper in the Nature issue of May 29, 2008, and Supplementary Materials. News & Views editorial by Zamponi. Press release. Nature Physics: Research Highlights, p435. Physics World. Science Daily. Physorg.com. Genetic Engineering & Biotechnology News.

    The following follow up papers are in cond-mat: Jamming I: A Hamiltonian for jammed matter. Jamming II: A phase diagram for jammed matter. Jamming III: Characterizing Randomness via the Entropy of Jammed Matter. Jamming IV: A distribution of volumes and coordination number in jammed matter: mesoscopic approximation. Jamming V: Jamming in two dimensions.

  • Hernan Makse is honored by the Mayor of New York City with the Mayor's Award for Excellence in Science and Technology to Young Investigator for playing with sand [press release of the New York Academy of Science, newspaper, pdf].

  • We are studying Dynamics of Social Networks and Urban Dynamics in collaboration with Dr. Lazaros Gallos (University of Thessaloniki), Prof. Shlomo Havlin (Bar-Ilan University), Prof. Fredrik Liljeros (Stockholm University), and Prof. Michael Batty (University College London).

  • How to calculate the fractal dimension of a complex network: the box covering algorithm. Can you improve the box-covering of a network? Download the algorithms and Databases of complex networks used in our studies to calculate the fractal dimension of a complex network. Including our PNAS paper on Scaling Theory of Transport in Complex Biological Networks in the May 2007 issue (pdf, supplementary information)

  • Colloids aging at equilibrium. From the August 2006 issue of Nature Physics.

  • Origin of fractality in complex networks: Be fractal and be robust From the April 2006 issue of Nature Physics

  • Complex networks: What is the relation between these Romanesque broccolis and the protein-protein interaction network of E.coli? From the January 2005 issue of Nature.

    Romanesque networks: News and Views Editorial in the January 27th, 2005 issue of Nature.

  • Research on thermodynamics of jamming: Simulations and experiments are being performed to investigate the statistical mechanics of jammed particulate matter.

  • Measuring the temperature of sand.

  • Statistical Mechanics of Jammed Matter: Jamming is even cooler than you thought. A review article by H. A. Makse, J. Brujic and S. F. Edwards.

  • Jamming in a box: See a recent News Feature in the October 19th, 2003 issue of Nature.

  • Taking the temperature: A News and Views Nature Editorial by Bob Behringer.

Specials

In a broader context, we try to follow the precepts of the Chinese Tao-te Ching (in Sanskrit according to Joseph Campbell): "He who thinks he knows, does not know. He who knows that he does not know, knows. For in this context, to know is not to know. And not to know is to know," since "one thing only we know, and that is that we know nothing," paraphrasing Socrates. In a more poetic way, we remember the great Don Atahualpa Yupanqui--- commemorating “El Año Yupanquiano&rdquo, 100 years of his natalicio--- saying: ... cuando se abandona el pago, y se empieza a repechar, tira el caballo adelante, y el alma tira pa' tras...

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