Current status of statistical mechanics in Armenia

Armen Allahverdyan(Yerevan Physics Institute)

-- Introduction: subject of statistical mechanics

-- Stat mech/thermodynamics of (small) engines

-- Interdisciplinary stat mech: evolution theory

-- Biological stat mech: presentation by E. Mamasakhlisov

Statistical mechanics: Explain macroscopic (many-body) regularities from microscopic conceptsPredict new macroscopic effects

Tools: classical or quantum mechanics + probability theory and statistics

Statistical physics in Yerevan Physics Institute : 4 groups

Method of presentation: focus on 1 important scientific questions for each subject

Drawbacks: no focus on answers; activities are not fully covered

Experiments: engineering thermodynamics, cond-mat, biophysics

1. Statistical mechanics of (small) heat engines

A. Allahverdyan (YerPhi),

K. Hovhannisyan (former PhD in YerPhi, now postdoc in Barcelona)

W. Deng (PhD student, France)

Support:

Volkswagenstiftung (2007-2010), NSF-USA (2008-2012) DARPA (2012-…)RRS-(Pays de la Loire, France) (2011-2013)PCR (China) Academy of Sciences (2011-2013) (to W. Deng)

SC-Armenia (2011) (to K. Hovhannisyan)

Frequent structure of theoretical physics working group in Armenia : 1 researcher + PhD student(s) + western-eastern collaborators

Cyclic engine

Work-source

1T 2T

Hot bath Cold bath

1 2 0W Q Q Work: Power:

1/W Q Efficiency:

/ cycleW

output / input

1Q2Q

W

Principal scheme of a (external combustion) heat engine

First law: 1/ 1W Q

Second law: 2

1

1T

T Carnot (maximal) efficiency

Efficiency-power dilemma: power goes to zero whenever2

1

1T

T

Question: how to make engines both powerful and efficient

Laws of thermodynamics

Gasoline car: 25--30 % , Diesel: 35 -- 40%

Allahverdyan et al, 2005—2013 Physical Review E, APhysical Review Letters, Physics Reports

Answer: study engines from within stat mech; microscopic origins of the power-efficiency dilemma (weak law)

Experimentally motivated activity with YerPhi biophysics group by S. GevorkianExplaining micromechanical/thermal experiments on bio-engines (haemoglobin)

Gevorkian, Allahverdyan et al, Physical Review Letters 2009, Europhysics Letters 2009, 2011

2. Statistical mechanics of evolution theory

D. Saakian (YerPhi),

Z. Kirakossyan (PhD in YerPhi)

CRDF (2007-2010), NSF-Taiwan (2008-….) DARPA (2011-…)

Statistical mechanics explaining virus evolution theory

Specific points of virus evolution

High mutation rates the unit of evolution is a group of connected genes

Asexual reproduction, but with horizontal gene transfer: connected population, many-body problem statistical mechanics is necessary

Accurate experimental realizations

Question: microscopic theory of virus evolution for a finite population of viruses

Answer : extract dynamical behaviour from the existing models (quasi-species model).

Construct new models.

Saakian et al, 2005—2012 PNAS (USA), Physical Review E

Conclusion

Reviewed activity of 2 groups doing theoretical statistical mechanics at Yerevan Physics Institute

Third group doing statistical mechanics at YerPhi is led by Prof. N. Ananikian.

Biologically motivated statistical physics talk by Prof. Mamasakhlisov

More stat-phys, talk by Vadim Ohanyan tomorrow