An interview with Professor Eli Barkai on the occasion of his winning the Bruno Prize
About five years ago, Prof. Eli Barkai, a physicist from Bar Ilan University, began to study the light emission of nano crystals (a crystal with a typical size of a billionth of a meter that behaves like a molecule). Understanding the nature of light emissions from such a small source stems not only from scientific curiosity, but also from possible applications in the field of nanotechnology.
The field of nanotechnology combines for the first time interdisciplinary studies between subjects that were previously quite separate - physics, chemistry and biology. Innumerable applications are planned for nanotechnology in different and varied fields, starting from countermeasures weapons, through lighter aircraft to medicine. In the field of medicine, the basic idea is to build machines of the size of a billionth of a meter, which will perform what machines on a visible scale do, for example for diagnosis, and therefore will be able to perform their duties in places that cannot be accessed in any other way, and moreover, they will be able to sail like a submarine inside the human body in order to attack cancer cells that have just begun to develop, or break down infections.
There are still many difficulties on the way to building nano-submarines that will tour the human body. One of them is that the designers of these systems need a kind of nanometer flashlights that will light the way for them within the target area of their product, in particular when it comes to a biological body, not to mention - the human body. For example, some wish to attach light-emitting markers to a biological system, such as a messenger RNA molecule. To see where the molecule or the "submarine" is going, they must be equipped with the nanometer equivalent of headlights.
But in order for the nanotechnologists to be able to develop their products, they must have a theoretical background, and this is provided by Barkai, among others. The theoretical background can outline new directions, or close the door on research directions where no technology can overcome a basic law of nature. The phenomenon Prof. Barkai is investigating is the flickering phenomenon of the nanometer crystals, which are actually the flashlights.
"At the level of the single molecule (single nano crystal) new physical and statistical phenomena were discovered. In the past, it was assumed that each molecule behaved as the average of the behavior of many molecules of its type, a fact that does not coincide with the modern experiment of the 21st century."
One of the phenomena discovered in nanocrystals is the flickering phenomenon. When we look at a city from space, we do not notice that the lights are flickering because the average light from the many sources in the city does not change to a great extent. On the other hand, when we look at a single flashlight, it may flicker, but we still see light most of the time. However, in the small dimensions, these are unstable systems. It's unthinkable that on a one-hour drive one night, the car's lights will turn on and off alternately so you can somehow see the road, while the next day the lights won't come on for the entire drive. In nanocrystals this happens a lot. The "lights" can turn off for a millisecond, turn on again and suddenly disappear for seconds, minutes or even hours.
Prof. Barkai and his colleagues developed theories that explain the behavior of nanocrystal systems, including the cause of flickering, the statistical properties of flickering and the difference between the prediction of quantum mechanics and these statistics and the actual situation. It turns out that a fundamental assumption known as the 'ergodic assumption' - according to which the average emission of a signal from a single system (for example an incandescent light bulb) will be the same across many identical systems (lamps of the same type) - does not hold.
One of the absurd consequences is that when a student is sent to measure the emissions from those nanocrystals, not only the random signal obtained is different from experiment to experiment, but also the average results differ from one series of experiments to the next, and this has nothing to do with the talent of that student, but with the lack of logic in the nanometric system. The theory developed by Barkai and his colleagues, and which was also tested by colleagues from the field of experimental physics at Bar-Ilan, makes it possible to predict the distribution of sample means and provides the formula for this.
Whether this is an obstacle that can be overcome, or whether it is a natural phenomenon that cannot be bypassed is the one that will forever distance the use of nanocrystals from the developers of nanometric systems, only time will tell. Prof. Barkai believes that the evidence is accumulating in this direction, but the flickering phenomenon must be continued to be studied in order to fully understand it in order to know this.
Where do you see yourself in five years?
"I really hope to learn new subjects and quickly. The award will allow me to collaborate with senior researchers abroad who will introduce me to new areas of research. I hope that even in five years I will continue to work with students and break into new directions, for example, to discover the behavior of individual molecules inside the cell."
How do you encourage the youth to pursue a scientific career?
"Contrary to what is written in the press, I come across students every day, some of whom are excellent, I have taught for many years at universities in the United States and our students for the most part do not fall short of the students at the best universities in the USA. The Israeli student has a natural curiosity. Sometimes he is a bit cheeky but the cheekiness sometimes indicates a tendency to ask questions all the time. Those who love science and come to make a scientific career will have a lasting experience and a priceless pleasure. Those who understand understand, and those who don't, better go learn other things."
Who has influenced your professional life the most?
My high school math and physics teacher Mr. Roth. He spent half his time in class telling jokes and then, with extreme clarity, explaining Newton's innovations. No one at school used so few words to explain profound ideas better than Mr. Roth.
Prof. Eli Barkai He began his academic career at Tel Aviv University, where he studied with Prof. Victor Floriov in the Department of Physics, and collaborated in research with Prof. Yossi Klifter from the Department of Chemistry. Later he stayed at important universities in the USA: MIT where he worked with Prof. Robert Silbey (SILBEY) and the University of Notre Dame. When he returned to Israel, he was accepted by Bar Ilan, he published many articles and in 2006 he even won the Krill Prize for Scientific Research, a prize awarded by the Wolf Foundation to young Israeli scientists.
On the same topic on the science website:
14 תגובות
To Eyal
The use of "lit" nanoparticles makes it possible to significantly improve the technology of photodynamic therapy.
More places and technologies that are too short to detail here will see this as fruit.
Yoav
What will be the statistics of turning off and on the "lights" as you call them?
In equilibrium of the crystal with the radiation this is determined by the temperature of the crystal and the Boltzmann distribution.
Prof. Barkai's research shows that this is not the case. As you know there is no good theory that describes the behavior of systems out of thermodynamic equilibrium, on the other hand Prof. Barkai found a way to describe the behavior of the system,
This is if I understood the article correctly.
Any system containing many oscillators with a similar but not identical wavelength will look like (in analogy to car headlights)
Car headlights that turn on and off chaotically and at the frequency of the frequency difference.
If there were only two close frequencies the lights would flash steadily at the frequency of the frequency difference.
If there are 10 crystals and each one has a slightly different frequency you will get chaotic lighting.
It is not clear what the new physics is here and why does it jump the forum?
to Yoav L
It is advisable to read the article carefully before responding. The "strange behavior" as she called it is not the reason for the flickering but why different models give a different distribution of dark light over time.
The question the researchers sought to answer is: "Not only does the random signal obtained differ from experiment to experiment, but also the averages of the results differ from one series of experiments to another." If the model is macroscopic then the average of the readings should have been the same assuming that the system is in thermodynamic equilibrium. breaking
of the ergodic principle (equivalence of averaging over time to averaging over energy) allows different models to give different distributions of light and darkness over long periods of time.
The question is not to find the physical mechanism for blinking in a specific nanocrystal!
Yoav to:
You overdo it!
If you didn't understand - get back to me in this forum.
sympathetic:
There is no doubt that funding plays a part in this but I think it is important to emphasize the difference between basic science and technology and nanotechnology, in my opinion, deserves its own name for the reason I mentioned.
Technology is inherently multidisciplinary because its purpose is to produce a solution to a particular problem regardless of a specific basic science.
Microscale systems may include applications of several fields of knowledge, but their development will be carried out by a team whose leaders at least know the results of several types of basic science and understand the common denominators of systems of this size.
Michael
It is possible that the physical laws on the scale of individual atoms are indeed different and indeed were
In physics there is a field called mesoscopy (part of the field of solid state) from here
Until the unification of biology and chemistry on this scale the road is still far.
The union of the above areas is forced and created for funding purposes.
Dear Eli Barkai
The reason for the apparent "strange" behavior is the interference of two close frequencies within the crystal and resulting from the fact that the crystal is not perfect.
I will give you an example if there are parallel faces that are not actually 100% parallel, possibly as a result of contamination or as a result of the properties of the material. In this case the crystal will be able to enter into resonance at two or more frequencies that are close to each other and vary slowly and interfere in a variable way as a result of temperature changes. small
From the outside it will look as if the crystal is behaving chaotically.
If you don't understand, get back to me in this forum.
sympathetic:
In my opinion, we usually talk about nanotechnology and not about nanoscience.
I think this makes sense because it is likely that several solutions from this field will find their place in the same system.
Beyond that - there really are physical laws that are manifested only in these orders of magnitude and not in higher orders of magnitude, and as a result the design of a nano system is different from the design of a larger system.
It is not clear to me what the nano world or nano science is.
The term "nano" is a market concept and not a scientific one. It was like we called the scientific field "the science of the meter"
When in meter science they include all the physical phenomena that occur in meter scales,
All biology that takes place on a meter scale, etc., etc.
There is almost no connection between the different fields that study the nano and if a connection is found between them it is often forced
to win grants. I therefore propose to change the name of "nano science" to "small science".
Eyal:
Indeed, flashlights are not the only solution, but that's what the guy is researching right now.
We should also remember that our goal in medicine is not to do what nature does anyway, but rather things that nature has failed to do. After all, there is no need to heal a person whose natural mechanisms have already healed him.
To Eyal
Your question/comment shows that one should be optimistic and nature has apparently found a solution to the flickering problem!
Maybe the answer is the need to send a quantity of nano machines?
I would investigate if a single white cell knows how to do the job alone or if it fakes when alone.
Good luck to Professor Eli Barkai in the future.
Shabbat Shalom
Sabdarmish Yehuda
I didn't understand the part with the headlights, can someone explain to me? Why do the nano-submarines that will patrol inside our bodies (in the bloodstream I imagine) need flashlights? Are these submarines supposed to include a camera that will transmit images to a computer that will analyze them? After all, even our white blood cells are actually a type of nano-submarines created by nature, how are they able to locate and eliminate viruses and bacteria without the need for flashlights? Why can't the nano submarines we built work in a similar way?
I wonder if the island of ergody is related to interweaving.
My feeling says yes.