The disappointing story of superconductivity in Strontium Ruthenate

In 1994 superconductivity was discovered in strontium ruthenate (Sr2RuO4). This attracted considerable interest because it had a perovskite crystal structure, just like the cuprates. Furthermore, it was a stoichiometric compound and so not plagued by impurities like the cuprates.

In 1998, things got more interesting when NMR Knight shift measurements were interpreted as evidence for triplet superconductivity.

Analogues were made with triplet Cooper pairing in superfluid 3He mediated by ferromagnetic spin fluctuations.

Triplet pairing is associated with odd-parity (spatial) and time-reversal symmetry breaking. Evidence for the latter was claimed from muon spin relaxation (muSR) and the polar Kerr effect.

There are subtle questions about whether a bulk sample of a triplet superconductor exhibits spontaneous magnetisation. Leggett discussed this in an Appendix of his textbook. It turns out the magnetisation probably only exists on the edges.

Aside. The metallic phase is of interest because (unlike the cuprates) it is a Fermi liquid. More recently, it has been argued to be a Hund's metal.

Fueled by hype about topological quantum computing, the past two decades have seen even greater interest in the material due to proposals that it may be a topological superconductor. See for example, this paper.

Now we come to the disappointment. It turns out that the original Knight shift measurements were flawed, probably due to a problem with thermometry.

Recent, careful Knight shift measurements suggest spin-singlet pairing. They were described in a Physics Today article by Alex Lopatka in 2021, An unconventional superconductor isn’t so odd after all. The article describes all the intricacies and challenges of these measurements. Stuart Brown is to be commended for persisting with this problem.

What about the Kerr effect and muSR measurements suggesting time-reversal symmetry breaking?

The polar Kerr effect involves rotation of the plane of polarisation of the electromagnetic radiation by an angle of 65 nanoradians! There is only one group in the world (at Stanford) that can detect these ultra-minute rotations.

muSR may also be problematic. It is not really known where the implanted muon sits in the crystal or what effect it has on the surrounding crystal structure. In particular, these perturbations may produce a small local magnetic field which is nothing to do with the claimed global field due to the magnetism associated with the triplet superconductivity. A recent preprint by Warren Pickett considers some of the challenges associated with interpreting these experiments as evidence for time-reversal symmetry breaking.

What is disappointing about this?

Obviously, it would be nice to have a triplet superconductor and even more a topological one.

However, for me, the big disappointment is that it took almost thirty years for the original NMR measurements to be checked and shown to be wrong. This may reflect several sociological problems.

Kauzmann's maxim: people will tend to believe what they want to believe rather than what the evidence before them might suggest.

The condensed matter community tends to be infatuated with exotica.

There is not enough application of Occam's razor. Luxury journals don't want simple explanations or authors to raise doubts or ambiguities.

As far as I am aware, the 1998 Nature paper on the NMR Knight shift has still not been retracted.

This post was stimulated by a helpful colloquium at UQ given recently by James Annett. He has worked on strontium ruthenate for many years and is a co-author of a relevant review article.

Update. 23 April. James Annett pointed out to me that the authors for the 1998 NMR published a paper in 2020 which acknowledges that their original paper was incorrect.

Reduction of the 17O Knight Shift in the Superconducting State and the Heat-up Effect by NMR Pulses on Sr2RuO4

A few things condensed matter physics has taught me about science (and life)

We all have a worldview, some way that we look at life and what we observe. There are certain assumptions we tend to operate from, often implicitly. Arguably, our worldview is shaped by our experiences: family, friendships, education, jobs, community organisations, and our cultural context (political, economic, and social).

A significant part of my life experience has been working in universities as a condensed matter physicist and being part of a broader scientific community. Writing a Condensed Matter Physics: A Very Short Introduction crystallised some of my thoughts about what CMP might mean in broader contexts. I am more aware of how my experience in CMP has had a significant influence on the way I view not just the scientific enterprise, but also broader philosophical and social issues. Here are a few concrete examples.

Complex systems. The objects studied in condensed matter physics have many interacting components (atoms). Further, there is an incredible diversity of systems (materials and phenomena) that are studied. Many different properties and parameters are needed to characterise a system and its possible states. There are many different ways of investigating each system. Similarly, almost everything else of interest in science and life is a complex system.

Emergence. This is central to CMP. The whole is greater than the sum of the parts. The whole is qualitatively different from the parts. Related features include robustness, universality, surprises, and the difficulty of making predictions. An emergent perspective can provide insights into other complex systems: from biology to psychology to politics.

Differentiation and integration. A key aspect of describing and understanding a complex system is conceptually breaking it into smaller parts (differentiation), determining how those parts interact with one another, and determining how those interacting parts combine to produce properties of the whole system (integration).

Diversity: The value of multiple perspectives and methods. Due to the complexity of condensed matter systems, multiple methods are needed to characterise their different properties. Due to emergence, there are various scales and hierarchies present. Investigating and describing the system at these different scales provides different perspectives on the system. What does the scientist do with all these different perspectives? Interpretation and synthesis are needed. That is not an easy or clearcut enterprise.

 Navigating the middle ground. The most interesting CMP occurs in an intermediate interaction regime that is challenging theoretically. Insight can be gained by considering two extremes that are more amenable to analysis: weak interaction and strong interaction. I had fun using conservative-liberal political tensions as a metaphor for divisions in the strongly correlated electron community.

The Art of Interpretation. Everything requires interpretation: a phone text message, a newspaper article, a novel, a political event, data from a science experiment, and any scientific theory. With interpretation, we assign meaning and significance to something. How we do this is complex and draws on our worldview, both explicitly and implicitly. Regardless of our best intentions, interpretation always has subjective elements.

Synthesis. Given the diversity of data, perspectives, and interpretation, it is a challenge to synthesise them into some coherent and meaningful whole. All the pieces are rarely consistent with one another. Some will be ignored, some discarded, some considered peripheral, and others central. This synthesis is also an act of interpretation.

All models are wrong but some are useful. One way to understand complex systems is in terms of "simple" models that aim to capture the essential features of certain phenomena. In CMP significant progress (and many Nobel Prizes) has resulted from the proposal and study of such models. There is a zoo of them. Many are named after their main inventor or proponent: Ising, Anderson, Hubbard, Heisenberg, Landau, BCS,... All theories in CMP are also models since they involve some level of approximation, at least in their implementation. These models are all wrong, in the sense that they fail to describe all features and phenomena of the system. But, the best models are useful. Their simplicity makes them amenable to understanding, mathematical analysis, or computer simulation. Furthermore, the models can give insight into the essential physics underlying phenomena, predict trends, or be used to analyse experimental data. 

The autonomy of academic disciplines. Reality is stratified. At each level of the hierarchy, one has unique phenomena, methods, concepts, and theories. Most of these are independent of the details of what happens at lower levels of the hierarchy. Given the richness at each level, I do not preference one discipline as more fundamental or important than the others.

Pragmatic limits to knowledge. We know so much.  We know so little. On the one hand, it is amazing to me how successful CMP has been. We have achieved an excellent understanding, at least qualitatively of many emergent phenomena in systems that are chemically and structurally complex (e.g., liquid crystals and superconductivity in crystals involving many chemical elements). On the other hand, there are systems such as glasses and cuprate superconductors that have been incredibly resistant to understanding. Good research is very hard, even for the brilliant. Gains are often incremental and small. This experience leads me to have sober expectations about what is possible, particularly as one moves from CMP to more complex systems such as human societies, national economies, and brains.

Science is a human endeavour. Humans can be clever, creative, insightful, rational, objective, cooperative, fiercely independent and capable of great things. The achievements of science are a great testimony to the human spirit. Humans can also be stubborn, egotistical, greedy, petty, irrational, ruthlessly competitive, and prone to fads, mistakes and social pressures. Science always happens in a context: social, political, cultural, and economic. Context does not determine scientific outcomes but due to human nature, it can corrupt how science is done.

The humanity of scientists leads to a lack of objectivity captured in Walter Kauzmann's maxim: people will tend to believe what they want to believe rather than what the evidence before them suggests that they should believe. My decades of experience working as a scientist leads me to scepticism about extravagant claims that some scientists make, particularly hype about the potential significance (scientific, technological, or philosophical) of their latest discovery or their field of research. Too often such claims do not stand the test of time.

Humility. This brings together practically everything above. The world is complex, people are complex, and human-world interactions are complex. It is easy to be wrong. We often have a pretty limited perspective of what is going on. 

What were the intellectual highlights of your undergraduate education?

I think one of the greatest moments of being a teacher or student is when the student understands or learns something that they find exciting, satisfying, or stimulating. In this "Ah hah!" or Wow! moment they will say "That is really cool!" or "That is beautiful!" or something similar.
These moments can be so significant that the student can years later even remember the exact time, location, or circumstance in which the event happened.

Did you have any such experiences when you were an undergraduate?

I reflected on my own experience. Even though it is almost 40 years ago I can remember what I learnt and sometimes the place, the book, the person, ...
Here is some of the things that immediately came to mind. They are listed in random order. It is interesting that many involve learning how one result follows from a more fundamental result with a simple mathematical proof. Often it meant there was a deeper reason for something we had previously been told was "just the way it is".
Most of these beautiful moments were in theoretical physics and pure mathematics. None were in chemistry. I think this was partly because of my own interests and orientation and partly because of the quality (or lack thereof) or approach to teaching of different subjects.

Ehrenfest's theorem
The equations of motion of classical mechanics are the average of the equations of motion for position and momentum operators.

Heisenberg's uncertainty relation follows from commutation relations.

The energy eigenvalues for the harmonic oscillator can be derived from the commutation relations of creation and annihilation operators.
No differential equations or Hermite polynomials were required!

Experimental test of time dilation from measurement of the lifetime of cosmic-ray mesons
I read about this in the textbook on Special Relativity by French. The experiments are described here.

van der Waals interaction from the Schrodinger equation
I learnt this derivation from reading my father's copy of Quantum Chemistry (1957) by Walter Kauzmann.

Electromagnetic radiation and the speed of light from Maxwell's equations

The ideal gas equation of state from the partition function

The logical structure of the laws of thermodynamics
I learnt this axiomatic approach from Hans Buchdahl, both from his book and his lectures.

Functional analysis and the equivalence of matrix and wave mechanics
This was in a pure mathematics class. It is really just an isomorphism of Hilbert spaces.

Evaluation of infinite series from residues in complex analysis
Cauchy's residue theorem can be used.

Dimensional analysis in fluid mechanics
It was amazing the physical insights one could gain simply from dimensional analysis.

Newtonian gravity from Einstein's gravitational field equations

What were some examples from your own undergraduate education?
How do we create such moments for students?

A basic but important research skill, 6: skepticism

Feynman said "The first principle is that you must not fool yourself and you are the easiest person to fool."

Walter Kauzmann emphasised that people will often believe what they want to believe rather than what the evidence before them suggests they should believe.

Students need to learn skepticism. Furthermore, it needs to be modelled to them by their advisors.
In particular, students should not just believe something because

- their advisor/supervisor believes it or tells them it is true
- it has been published, especially if it is in a luxury journal
- someone famous [or a group of famous people] claims it is true
- it is an exciting idea.

Basic but important questions to ask are:

What is the evidence? How reliable is the evidence?
Is there an alternative explanation, particularly a simpler one?

Maybe I am just becoming a grumpy old man, but I think I do increasingly encounter students and young researchers who lack this basic skill.
I fear that this is because of the seductive power of "sexy" explanations and topics. Furthermore, some of the students mentors and role models don't model or practise skepticism, particularly if their career success and funding [or hope thereof] depends on the exotica favoured by the luxury journals.

Good science is just plain hard work and not as exciting or clear cut as we might wish.

The challenge of writing books on water

Biman Bagchi has just published a new book,
Water in Biological and Chemical Processes: From Structure and Dynamics to Function 

Cambridge University Press sent me a complimentary copy to review. I am slowly working through it and will write a detailed review when I am done.

I think this is a very challenging subject to write a book on for at least three reasons. First, the scope of the topic is immense. Furthermore, it is multi-disciplinary spanning physics, chemistry, and biology, with a strong interaction between experiment, theory, and simulation. Second, although there have been some significant advances in the last few decades there is real state of flux, with a fair share of controversies, advances, and fashions. Finally, which audience do you write for? Experimental biochemists or theoretical physicists or somewhere in between.

Although this is an incredibly important and challenging topic few authors have taken up the challenge. One who has is Arieh Ben-Naim

Molecular Theory of Water and Aqueous Solutions, Part I: Understanding Water (2009)

Molecular Theory of Water and Aqueous Solutions Part II: The Role of Water in Protein Folding, Self-Assembly and Molecular Recognition (2011)

This was a topic of great interest to my late father. He wrote two comprehensive reviews with John Edsall, published in Advances in Biophysics

Water and proteins. I. The significance and structure of water; its interaction with electrolytes and non-electrolytes (1977) [does not seem to be available online]

Water and proteins. II. The location and dynamics of water in protein systems and its relation to their stability and properties (1983)

Classic earlier books include:

The Structure and Properties of Water
 by David Eisenberg and Walter Kauzmann
(1969, reissued in 2002 by Oxford UP in their Classic Texts in the Physical Sciences)

A seven volume series, Water: A comprehensive treatise, edited by Felix Franks

At the popular level there is
Life's Matrix: A Biography of Water 
(2001) by Philip Ball

A key concept in glasses: the entropy crisis

The figure below introduces the idea of an "entropy crisis" and the Kauzmann temperature in glasses. It also leads to profound and controversial questions about the intimate connection between thermodynamics and kinetics in glasses.

Each solid curve shows the temperature dependence of the entropy of a supercooled liquid, relative to that of the crystal, above T_g, the glass transition temperature. T_m is the melting temperature of the crystal. The dashed curves are entropy in the glassy state.

The figure is taken from a very helpful review and adapted from Walter Kauzmann's classic 1948 paper.

What is going on?
The entropy of a liquid is greater than a solid [think latent heat of melting] so Delta S is positive. But, the specific heat capacity of a liquid is also greater than that of a solid [the vibrational, translational, and rotational degrees of freedom are all "softer" and less constrained]. Hence, the slope of Delta S vs. T must be positive.
Now, suppose that the liquid is supercooled so incredibly slowly that the glass does not form and you keep lowering the temperature, then at some temperature Delta S becomes negative. This extrapolated temperature [see the light blue straight line] is known as the Kauzmann temperature.

Why does this matter?
By the third law of thermodynamics, the entropy of the crystal goes to zero as the temperature goes to zero. Thus the supercooled liquid, could have negative entropy, which is physically nonsense.
Formation of the glass prevents this possibility. But, formation of the glass involves kinetics. So is there some deep connection between thermodynamics and kinetics? The review  discusses some possible connections. The extent of that connection is one of the controversial questions in glasses.

How 5 years of blogging has changed me

Last month marked the 5 year anniversary of this blog. My first post was a tribute to Walter Kauzmann. In hindsight, after almost 1500 posts, I think that was a fitting beginning. Kauzmann represented many of the themes of the blog: careful and thorough scholarship, theory closely connected to experiment, simple understanding before computation, hydrogen bonding, fruitful interaction between chemistry and physics, ….

Reflecting on this anniversary I realised that writing the blog has had a significant influence on me. Writing posts forces one to be more reflective. I think I have a greater appreciation of

• good science: solid and reproducible, influential, ...
• how important it is to good science, rather than just publishing papers
• how hard it is to do good science
• today, the practise of science is increasingly broken
• the bleak long-term job prospects on most young people in science
• the danger and limitations of metrics for measuring research productivity and impact
• the importance of simple models and physical pictures
• diabatic states as a powerful conceptual, model building, and computational tool in chemistry
• the importance of Dynamical Mean-Field Theory (DMFT)
• bad metals as a unifying concept for strongly correlated metals

I thank all my readers, and particularly those who write comments.
I greatly value the feedback.
I do want to see more comments and discussion!

New horizons in hydrogen bonding

If it's tuesday, this must be Belgium. Somehow I can't get that out of my head, partly because I have been travelling a lot. I first saw the movie in 1969, strangely in Princeton, while on an 3 month overseas trip with my parents. My father was visiting Walter Kauzmann, who knew all about hydrogen bonding. I think we thought the movie was pretty funny. I was only 8 years old. But I watched it again a few years ago and did not think it was that funny anymore. But, I digress...

This week I am in Antwerp, Belgium attending the 20th International Conference on Hydrogen Bond Research. Why am I here? It is part of the process of trying to break into a new field.

The program and attendees are diverse ranging from theoretical physicists like me to quantum chemists to experimental physical chemists to biochemists. The challenge for me will be filtering through all the chemical detail to figure out what is really important and what is not. I am looking forward to learning more about halogen bonding, a hot topic lately. How is it similar and different from hydrogen bonding? In the abstract book I also found some interesting talks and posters, including the figure below, that looks pretty exciting to me.

I am giving a talk on tuesday about my simple model for hydrogen bonding and the role of quantum zero point motion.

When a Dean fakes data

The Sunday New York Times magazine has a fascinating and disturbing article The Mind of a Con Man about Diederik Stapel, former Dean of Behavioural and Social Sciences, at Tilburg University in the Netherlands. He had a stellar academic career which was based on fabricating experimental data.

The article is rather long but worth reading. Here are a few of the extracts I found particularly pertinent:

Stapel did not deny that his deceit was driven by ambition. But it was more complicated than that, he told me. He insisted that he loved social psychology but had been frustrated by the messiness of experimental data, which rarely led to clear conclusions. His lifelong obsession with elegance and order, he said, led him to concoct sexy results that journals found attractive. 

In his early years of research — when he supposedly collected real experimental data — Stapel wrote papers laying out complicated and messy relationships between multiple variables. He soon realized that journal editors preferred simplicity. 

What the public didn’t realize, he said, was that academic science, too, was becoming a business. “There are scarce resources, you need grants, you need money, there is competition,” he said. “Normal people go to the edge to get that money. Science is of course about discovery, about digging to discover the truth. But it is also communication, persuasion, marketing. I am a salesman. I am on the road. People are on the road with their talk. With the same talk. It’s like a circus.”  

Stapel’s atypical practice of collecting data for his graduate students wasn’t questioned,  [How many Deans do that ?] 

[The official report from the University stated] The field of psychology was indicted, too, with a finding that Stapel’s fraud went undetected for so long because of “a general culture of careless, selective and uncritical handling of research and data.” If Stapel was solely to blame for making stuff up, the report stated, his peers, journal editors and reviewers of the field’s top journals were to blame for letting him get away with it. The committees identified several practices as “sloppy science” — misuse of statistics, ignoring of data that do not conform to a desired hypothesis and the pursuit of a compelling story no matter how scientifically unsupported it may be.

It may be tempting for physicists and chemists to look down our noses at the social scientists, but I think these issues are just as pertinent for us. Don't forget Hendrik Schon!

As Kauzmann said: we tend to believe what we want rather than what the data tells us we should believe. Often the data is messy and inconclusive.

Our tendency to scientific fantasy not reality

More great quotes from Bob Laughlin, A Different Universe: Reinventing Physics from the Bottom Down

“The great power of science is its ability, through brutal objectivity, to reveal to us truth we did not anticipate.”
(p. xvi)

``mythologies are immensely powerful things, and sometimes we humans go to enormous lengths to see the world as we think it should be, even when the evidence says we are mistaken.’’
(p. 114)

“ideologies preclude discovery. All of us see the world as we wish it were rather than as it actually is.”
(p. 116).

There are similarities to the cautions of Walter Kauzmann, in his Reminiscences of a Life in Protein Chemistry.

The easiest person to fool is yourself

Key moderating principles I try to keep in mind as I struggle to understand complex molecular materials

-correlation does not imply causality

-extraordinary claims require extraordinary evidence

-Kauzmann's maxim: people will tend to believe what they want to believe rather than believing what the evidence before them suggests they should believe

-use the method of multiple alternative hypothesis

-be mindful of the dangers of curve fitting

-in systems with many degrees of freedom it is very hard to find control variables, because most variables are not independent of one another

-Feynman's warning: the easiest person to fool is yourself

Quantum decoherence in water

Water is an amazing substance which has many unique properties. Some of these properties are essential for the functionality of biomolecules.
Previously, I mentioned how it plays a key role in determining the spectral density which describes how electronic excitations in biomolecules decohere.
If one takes the simplest possible Onsager type continuum dielectric model where an electric dipole is placed inside a spherical cavity then the spectral density can be related to the frequency dependent dielectric function, epsilon(omega)For more on this see this review article.

The figure below [from a nice paper by Hsu, Song, and Marcus] shows a plot of -J(omega)/omega using the measured epsilon(omega) for liquid water at room temperature.

What is the origin of the large shoulder around 800 cm-1 (corresponding to a time scale of about 40 fsec)?

It is due to the "librational" motion of the water molecules. This is a rotational motion of an individual water molecule which is restricted by hydrogen bondint to four surrounding water molecules. A nice animation of the librational motion of water is here.

In heavy water, D2O, the librational frequency is decreased by a factor of about two.

The librational motion makes an important contribution to the heat capacity of water and ice, as described in the classic book of Eisenberg and Kauzmann.

Putting quantum conciousness to sleep

A video and book that has received a lot of attention in popular culture over the past few years is What the bleep do we know?

The protagonist, Amanda, played by Marlee Matlin, finds herself in a fantastic Alice in Wonderland experience when her daily, uninspired life literally begins to unravel, revealing the uncertain world of the quantum field hidden behind what we consider to be our normal, waking reality.

The video contains a strange mix of quantum physics, pop psychology, and new Age mysticism. A main thesis of the video is that there is a connection between quantum physics and how we think. Indeed, by thinking quantum thoughts we can create our own quantum reality and control our destiny. Since I am interested in science and theology several people had recommended it to me. A teacher at my daughter's school was enthralled with it, and encouraged students to watch it. When I finally watched the video I was alarmed. It completely mis-understands and mis-represents quantum physics. None of the scientists interviewed in the movie is actually a bona fide quantum physicist (i.e., someone who regularly publishes research papers in international refereed journals).

So what do we know? There are many things we don't understand. Quantum physics and consciousness are both strange and poorly understood. However, that does not mean they are related. There is a reality which is independent of what I think about it. How I think can have a significant effect on my perception of that reality, but it won't change that reality. This is psychology, but has nothing to do with quantum physics.


Stuart Hameroff, a Professor of Anesthesiology at the University of Arizona is featured in the video. He is a vocal proponent of "quantum consciousness" and has co-authored papers on the subject with Sir Roger Penrose FRS, a distinguished mathematical physicist.

Recently, Jeff Reimers, Laura McKemmish, Noel Hush, Alan Mark, and I published a detailed scientific critique of key ideas of Hameroff and Penrose in the Proceedings of the National Academy of Sciences (USA). You can read Hameroff's response here. The paper also stimulated some debate on the Nature network. I will leave you to draw your own conclusions about whether Hameroff's reponse is convincing.

My experience with this enterprise confirms Kauzmann's warnings.

Quantum dynamics of excited states of biomolecular chromophores

I am giving the Chemistry seminar at UQ this week. Here are the slides

Walter Kauzmann (1916 -2009): the master of thermodynamics

Walter Kauzmann was a pioneer in understanding condensed phases of matter. Two of his most important contributions to science (the hydrophobic interaction and a paradox concerning glasses) were made using his profound understanding of thermodynamics. He first introduced the notion of a hydrophobic interaction. Before any structures of proteins were known he deduced solely from thermodynamic data on the solvation of small organic molecules that a protein must fold so that the non-polar amino acids are predominantly in the centre of the protein. I discuss this in a lecture I often give to undergraduates at the University of Queensland in the course PHYS2020: Thermodynamics and Condensed Matter Physics.

Kauzmann wrote a beautiful article, Reminiscences of a life in protein physical chemistry, that I warmly recommend. One point he makes repeatedly in the article is that in science (and life) people will often believe what they want to believe rather than what the evidence before them suggests they should believe. The article recounts some of the "silly" things (from the perspective of our knowledge today) people believed about proteins in the 1950's, and how reluctant the advocates of these theories were to give up on them. Those of us trying to understand complex materials today, and especially biomolecular function, should be sobered and chastened by this lesson from history.

Kauzmann co-authored with David Eisenberg the definitive monograph on water and a beautiful "ancient" text, Quantum Chemistry (1957) which I found extremely helpful as an undergraduate and today.

Bruce Alberts testifies to Kauzmann's personal legacy in this fascinating article where he describes how Kauzmann mentored him. Alberts is currently the Editor in chief of the journal Science, a former past president of the National Academy of Sciences in the USA, and a co-author of the definitive text, The Molecular Biology of the Cell.

More about Kauzmann's life is available here. I was privileged to have some personal interaction with him, while a graduate student (in physics not chemistry) at Princeton, because he was a long-time friend of my late father. However, I did not realize what a great scientist he was and how much I could have learnt from him. Back then I was a some-what narrow-minded physicist who had not developed a fascination with problems at the interface of chemistry and physics. Youth is wasted on the young!