Life in Super-Resolution: Light Microscopy Beyond the Diffraction Limit

In 1979, South African Allan M. Cormack won the Nobel Prize in Physiology or Medicine for his development of X-ray computed assisted tomography (CT), which allows physicians to see internal bodily structures without cutting. A quarter of a century later, Sir Peter Mansfield of the United Kingdom was given the same award in 2003 for advances in magnetic resonance imaging (MRI) that led to scans taking seconds rather than hours.

Today, these two imaging techniques serve as essential diagnostic and investigative tools for both medicine and the life sciences. But one unique fact about Cormack and Mansfield stands out: Despite winning the most prestigious award in medicine, neither Laureate went to medical school nor had a background in biology — rather, they were both true-blue physicists.

Cormack spent most of his research career focusing on nuclear and particle physics, while his CT efforts remained an intermittent side project for almost two decades. For Mansfield, his postdoctoral work on nuclear magnetic resonance spectroscopy in doped metals gradually transitioned into scanning his first live human subject with the newly invented MRI technique.

The tradition of physicists driving advances in biomedical imaging continues, as made evident by the lectures of Steven Chu and Stefan Hell at the 66th Lindau Nobel Laureate Meeting. Both showed visually stunning examples of their research using super-resolution microscopy, a method that transcends the diffraction limit of conventional light microscopes to probe on a nanoscopic scale.

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Stefan Hell in discussion with young scientists at #LiNo16. Photo: Ch. Flemming/Lindau Nobel Laureate Meetings

“We learn in school that the resolution of a light microscope is fundamentally limited by diffraction to about half the wavelength of light,” said Hell, who gave his lecture on Thursday morning. “And if you want to see smaller things, you have to resort of course to electron microscopy.”

Hell, a physicist who currently serves as a director of the Max Planck Institute for Biophysical Chemistry in Germany, accomplished what was long thought to be the impossible. Using light microscopy and fluorescent labeling of molecules, he invented a super-resolution technique called stimulated emission depletion (STED) microscopy — the work that won him the 2014 Nobel Prize in Chemistry.

“The development of STED microscopy showed that there is physics in this world that allows you to overcome this diffraction barrier,” he said. “If you play out that physics in a clever way, you can see features that are much finer and details that are beyond the diffraction barrier.”

A conventional microscope cannot distinguish objects — say, molecules — that are packed within a space of about 200 nanometers because they all become flooded with light at the same time. Subsequently, a detector will simply record the scattering as a blurry blob of light without being able to image any individual molecules.

Hell got the idea of highlighting one molecule at a time by using fluorescent labeling, while also keeping other molecules in a dark state through stimulated emission. With a phase modulator, he could then force molecules in a doughnut-shaped area to stay dark and in the ground state while those in the center would produce light.

With this discovery, biomedical researchers could now image objects as tiny as proteins on the outside of a virus. For instance, STED microscopy was used to observe a major difference in envelope protein distribution that can be used to distinguish mature HIV that can infect cells versus those immature viruses that cannot.

“The misconception was that people thought that microscopy resolution was just about waves, but it’s not — microscopy resolution is about waves and states,” Hell emphasized. “And if you see it through the eyes of the opportunities of the states, the light microscope becomes very, very powerful.”

Steven Chu referenced Hell’s groundbreaking research during his lecture on Wednesday morning, which focused on his recent efforts in optical microscopy — quite a departure from his previous work in energy during a decade-long sabbatical.

“I sat down fresh out of government with no lab, no students, no postdocs, no money,” said Chu, who served as U.S. Secretary of Energy from 2009 to 2013. “The only thing that I could do was think, and that turns out to be liberating.”

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Steven Chu during his lecture. Photo: Ch. Flemming/Lindau Nobel Laureate Meetings

A venerable jack-of-all-trades, Chu received the 1997 Nobel Prize in Physics in yet another field — atomic physics — for his development of laser cooling and trapping techniques. His latest interest in microscopy grew out of a fascination with cell signaling and how dysfunctions in the process can lead to cancer.

“If you’re a cell embedded in an organism’s tissue, you don’t willy-nilly divide — that’s considered very antisocial behavior. You divide when the surrounding tissue says it’s okay to divide,” he described. “But if you willy-nilly divide and say ‘me-me-me,’ that is called cancer.”

Using imaging techniques, the cell signaling pathway can be investigated in detail to target areas that could prevent cancer from developing. Taking Hell’s work in super-resolution microscopy a step further, Chu discussed his use of rare earths embedded in nanocrystals to replace fluorescent organic dyes. A nanocrystal can be doped with 5,000 to 10,000 impurities so it emits a certain color in the near-infrared with a very narrow spectral peak. If each class of nanoparticle is synthesized to produce a different ratio of colors, this creates a spectral barcoding of probes.

The next step is to use nanoparticle probes to image molecules through tissue in a living organism without cutting. Adaptive optics — a technique that originated in astronomy — has been employed in order to take light scattering into account, enabling high-resolution microscopy of mouse brain tissue through an intact skull.

“The question is if you go deeper into the infrared, can you look not through 500 microns but maybe 5 millimeters?” said Chu. “This is an open question we’re working on this. We’ve gotten down to a millimeter but we’ll see.”

One of his ideas involves inserting nanoparticles into cancer cells and watch them over time in order to track which cells metastasize, with the ultimate goal of developing future therapies.

Carl Wieman: Teaching Science More Effectively

In the late 1980s when Carl Wieman was conducting his research at an atomic physics lab in Boulder, Colorado, he had many graduate students working in his lab. And repeatedly he would make the same observation: they came with excellent grades, had passed many physics courses and tests – but when given a research problem to work on, they were clueless how to proceed. They couldn’t think like scientists, i.e. they couldn’t break problems down, weren’t able to evaluate data, couldn’t question their own assumptions, etc. But “after just a few years of working in my research lab, interacting with me and the other students, they were transformed. I’d suddenly realize they were now expert physicists, genuine colleagues,” Wieman writes in his own blog on teaching science.

A passionate researcher by nature, Wieman was so puzzled by this persistent phenomenon that he approached it like any other research problem. One preliminary explanation he and his colleagues came up with was the ‘butterfly model’: Maybe the brains of all graduate students had to pass through a 17-year caterpillar phase before it could spread its butterfly wings and fly. But this explanation neither satisfied Wieman’s inquisitive mind nor was is very scientific. That’s when he started to approach this phenomenon with scientific methods: teaching several groups of undergraduate students with different methods and testing the outcome with a standardized test.

 

Wieman during his 2016 lecture at the 66th Lindau Nobel Laurate Meeting in Lindau. He's just explainin how taking notes actually distracts students from following the lecture. Photo: LNLM

Wieman during his 2016 lecture at the 66th Lindau Nobel Laurate Meeting in Lindau. He’s just explaining how taking notes actually distracts students from following a lecture. He received the 2001 Nobel Prize in Physics together with Eric Cornell for the first Bose-Einstein condensate. Photo: Ch. Flemming/Lindau Nonel Laureate Meetings

Last week at the 66. Lindau Nobel Laureate Meeting in Lindau, Carl Wieman outlined some of his findings in his lecture. According to his studies, students have the best test results if they learn a subject at home for one hour with good material from their professor; the second best if they listen to a lecture but don’t take notes. Interestingly students who revert to the classical learning method of attending lectures plus taking notes have the worst test results. What first seems surprising gets clearer when we think about this for a moment: note taking means you have to concentrate on at least two things at the same time: on the production of the notes (and their content will always lag behind the lecture) plus trying to follow the lecture that is proceeding regardless of the note-takers’ pace. Wieman calls this situation ‘cognitive overload’: if you try to memorize too many things simultaneously, in the end you will remeber very little.

Knowing this, it’s not surprising that Prof. Wieman and colleagues regularily encountered 50 percent drop-out rates from introductory science lectures, and over 10 percent failing rates of those who persisted. Furthermore, many students – among them many future teachers! – left college believing that physics and math were “uninteresting, irrelevant and unnecessarily hard to learn”, as Wieman writes in the New York Times. He continues: “After they take the typical undergraduate basic-science courses, they have more negative feelings toward the subjects than they did before.”

Wieman set out to change this: he donated his Nobel Prize money to his PhET initiative. In fact he had started to study ‘learning physics and how to improve it’ long before his Nobel prize, “it’s just that people didn’t pay attention to me until then,” he writes in Nature. From 2010-2012 he even served as associate director for science at the White House Office of Science and Technology Policy. He currently holds a joint appointment as Professor of Physics and of the Graduate School of Education at Stanford University.

 

 

After studying not only his own test results, but projects and tests from other researchers in the field of education psychology, Wieman designed a novel method to teach science: If students have to solve scientific problems in groups, discuss the tasks with each other and get frequent feedback from an instructor – they will start to think like scientists, they won’t drop out, and they will do much better in tests. “A key element involves instructors designing tasks where students witness real-world examples of how science works.” In his 2016 Lindau lecture Wieman explains that for building this kind of competence, “the brain needs to work really hard” to build up the relevant synapses – just reading notes isn’t enough for that. It’s like “building up a muscle”.

Teaching science in a way that basic concepts and approaches are understood and can be applied in various contexts isn’t only crucial for having better researchers in the future. “We need a more scientifically literate populace,” Wieman writes in a 2007 article, “to address the global challenges that humanity now faces and that only science can explain and possibly mitigate, such as global warming, as well as to make wise decisions, informed by scientific understanding, about issues such as genetic modification.” So teaching better science to a broader, more diverse population is also an inherently democratic approach to promote informed decision making, in contrast to political decision making that is mostly based on traditions or emotions.

The last event at the 2016 Lindau Meeting was the panel discussion ‘The Future of Education in Sciences’: Carl Wieman discussed his favourite subject with Nobel Laureates Dan Shechtman and Brian Schmidt on the beautiful Mainau island in Lake Constance, where Countess Bettina Bernadotte, Council President for the Lindau Nobel Laureate Meetings, grew up with her father, Count Lennart Bernadotte, one of the founders of the Lindau Meetings and also founder of the botanical gardens on the Mainau island.

 

 

#LiNo16 Daily Recap – Friday, 1 July 2016

On Friday, 1 July the 66th Lindau Nobel Laureate Meeting concluded with the traditional boat trip to Mainau Island, home of the Bernadotte family.

Video of the day

All lectures available now!

Head over to the mediatheque and relive all of the wonderful lectures held by Nobel Laureates.

Picture of the day

Nobel Laureate Bill Phillips with young scientists during the picnic on Mainau Island. Picture/Credit: Christian Flemming/Lindau Nobel Laureate Meeting

Nobel Laureate Bill Phillips with young scientists during the picnic on Mainau Island. Picture/Credit: Christian Flemming/Lindau Nobel Laureate Meeting

 

Blog post of the day

To search for dark matter with the help of antimatter sounds like something from a science fiction movie. But that’s what the Alpha Magnetic Spectrometer AMS was designed to do – the unique instrument is the brainchild of Nobel Laureate Samuel Ting.

Read article: How Positrons Can Help Explain the Universe

Tweets of the day

#LiNo16 Daily Recap: Thursday, 30 June

Please find below some of the highlights of Thursday, 30 June at the 66th Lindau Nobel Laureate Meeting.

Video of the day:

Browse through our mediatheque for more videos of #LiNo16.

 

Blog post of the day:

“Scientists as modern nomads in a globalised scientific world” – The question facing individual countries is: brain drain or brain gain?

 

Picture of the day:

Nobel Laureate Carl Wieman has dedicated himself to improving the way natural sciences are taught. Here interacts with one of the young scientists participants from #LiNo16.

Ch. Flemming/Lindau Nobel Laureate Meetings

Ch. Flemming/Lindau Nobel Laureate Meetings

For more pictures from the Lindau Nobel Laureate Meetings, past and present, take a look at our Flickr-account.

 

Tweets of the day:

#LiNo16 Daily Recap, Wednesday, 29 June 2016

Please find below some of the highlights of Wednesday, 29 June at the 66th Lindau Nobel Laureate Meeting.

 

Video of the day:

Browse through our mediatheque for more videos of #LiNo16!

 

Blog post of the day:

Large-scale quantum computing will change our lives as much as the internet revolution and cell phone revolution – when it materializes.

Read the article: “Quantum Computing: How, What, and Why”

 

Picture of the day:

Frankfurter Allgemeine Zeitung, one of Germany’s premier broadsheet papers hosted a very interesting press talk on artificial intelligence.

 

66th Lindau Nobel Laureate Meeting, 29.06.2016, Lindau, Germany,  Picture/Credit: Christian Flemming/Lindau Nobel Laureate Meetings

Participants of the press talk on artifical intelligence, from left to right: Yuan-sen Ting and Arrykrishna Mootoovaloo (young scientists), Turing-Award winner Vinton Cerf, Joachim Müller-Jung, head of the FAZ’s science/nature division, Prof. Rainer Blatt, 1 of 2 scientific chairmen of #LiNo16 and Mario Krenn from the Vienna Center for Quantum Science and Technology.

For more pictures from #LiNo16 take a look at our Flickr-account.

 

Tweets of the day:

 

Smartphones, Energy-Efficient Lamps, and GPS: How Nobel Laureates’ Work Impacts Today’s Technology

Particle physics and cosmology make up the big topics of interest for many young scientists at the 66th Lindau Nobel Laureate Meeting, with lectures by the pioneering researchers who won Nobel Prizes for their work in the cosmic microwave background radiation, neutrino mass, and the accelerating expansion of the universe. These fields embody the inquisitive and fundamental nature of physics as a discipline driven purely by a curiosity about what makes the world tick.

However, let’s not forget about the importance of more applied topics in physics, such as research in semiconductors, optics, medical physics, and nanotechnology. Physicists in these fields have contributed to groundbreaking developments in technology that impact not only society as a whole, but often affect our individual lives on a day-to-day basis.

Their work often teeters on the fuzzy border between science and engineering — a place Nobel Laureate Hiroshi Amano remains very familiar with. As one of the inventors of the once-elusive blue LED, Amano had a direct hand in the realization of full-color displays that grace our beloved smartphones, as well as the energy-efficient LED lighting quickly replacing incandescent and fluorescent bulbs.

“First of all, I’d like to mention that I’m not a physicist — I belong to the engineering department. So today, I’d like to emphasize the importance of not only the science but also the engineering,” said Amano, who kicked off the meeting’s Nobel Laureate lectures on Monday morning. “Maybe my field is not the major in this meeting, so I’d like to mention the importance of the minority.”

 

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Hiroshi Amano during his lecture. Photo: J. Nimke/Lindau Nobel Laureate Meeting

Amano began his lecture by describing his poor academic performance from primary school to high school. Since it seemed to him that the only reason to study hard in Japan was to get into a good high school or university, he lacked sufficient motivation. A former professor changed this mindset by describing the purpose of engineering as a discipline that connects and supports the people. From that moment on, Amano had no trouble finding the inner drive to study hard.

Despite his title as a Professor in the Department of Engineering and Computer Science at Nagoya University in Japan, Amano won the 2014 Nobel Prize in Physics along with Isamu Akasaki and Shuji Nakamura for the invention of high-brightness blue light-emitting diodes (LEDs). For three decades, the creation of a commercially viable blue LED remained a slow-going and difficult endeavor for researchers despite the previous success of red and green LEDs.

“Unfortunately, all the efforts in the 1970s failed,” said Amano, citing issues with growing crystals in the material of choice for blue LEDs, gallium nitride, as well as creating p-type layers. “So many, many researchers abandoned this material and started the new material research such as zinc selenide. Only one person could not abandon this material: my supervisor, Isamu Akasaki.”

In 1985, Akasaki and Amano successfully created their own crystal growth system by using a buffer layer of low-temperature-deposited aluminum nitride that sat between the gallium nitride and sapphire substrate. After a few more tweaks involving the p-type layer, the two presented the world’s first high-brightness blue LED in 1992.

The flashy new blue LEDs could now be combined with their classic red and green counterparts to produce full-color displays for smartphones, computer screens, and televisions. Energy-efficient and long-lasting lightbulbs that emit white light use blue LEDs along with yellow phosphor, and have already started to replace incandescent and fluorescent lighting around the world. By year 2020, the total electricity consumption in Japan could drop about 7% by swapping existing lamp systems to LEDs — a savings of 1 trillion Japanese yen.

Outside of cosmology and particle physics, another fundamental field of physics lies in studying the strange and often paradoxical quantum world. Many quantum phenomena were thought to exist only in a theorist’s mind, since direct experimental observation would destroy the individual quantum systems.

However, the work of Nobel Laureate David Wineland proved otherwise. In 2012, Wineland and Serge Haroche shared the Nobel Prize in Physics for their independent discovery of experimental methods that enable the measurement and manipulation of individual particles without destroying their quantum-mechanical nature. His research has enabled the creation of extremely precise atomic clocks, with more than 100-fold greater precision than the cesium-based clocks in standard use.

 

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David Wineland

“Certainly one of the applications of precise clocks over many centuries has been in navigation, and that’s still true today,” said Wineland during his lecture on Tuesday morning. “One system we take for granted is the [Global Positioning System (GPS)].”

Signals from satellites orbiting the Earth transmit their position and current time, which are then picked up by a GPS receiver. Given that the signals travel at the speed of light, the calculated time delays between the clocks of multiple satellites and those on the ground can be used to pinpoint the GPS receiver’s location on the surface of the Earth.

“There can be errors in the clocks, so for example if the clocks are synchronized to the nanosecond, then that gives an uncertainty of about 30 centimeters,” he said.

The standard atomic clocks in satellites today use an electronic transition frequency in the microwave range as a periodic event generator or frequency reference. Earlier examples of periodic event generators include the rotation of the Earth and the swing of a pendulum.

As Group Leader of the Ion Storage Group at the National Institute of Standards and Technology (NIST) in the U.S., Wineland began working on building a better clock in 1979 when he started to do experiments with atomic ions. The group trapped beryllium ions by surrounding them with electric fields and used tuned laser pulses to put the ions in a superposition state, or a simultaneous existence of two different energy states. A single ion trapped in this way could also be used to create an optical clock, based on optical rather than microwave transitions.

An optical clock’s precision can be better than one part in 10^17 — meaning that if you started the clock at the time of the Big Bang 14 billion years ago, it would only be off by about 5 seconds.

At the end of his lecture, Wineland described using his clocks for navigation at a scale of less than one centimeter. Not only would GPS calculations become much more accurate, but such clocks could even measure the dynamics of relative locations on Earth for earthquake prediction.

#LiNo16 Daily Recap, Monday, 27 June 2016

Yesterday, the scientific programme of the 66th Lindau Nobel Laureate Meeting commenced. It was a fantastic day full of science and exchange – this short recap can only give you a glimpse of everything that happened. You should definitely have a look at our mediatheque to see all the fascinating lectures!

 

Video of the Day:

This is not the only video from Monday! Browse through our mediatheque for more.

 

Blog Post of the Day:

A Beautiful Quest – The Search for a Unified Theory

The search for a single overarching theory of nature that describes all the fundamental physical forces and particles has been the major thrust of modern physics. Are we about to reach this elusive goal, or is it turning into a quixotic quest that needs to be abandoned?

Click here to read the essay.

 

Picture of the Day:

Nobel Laureates Chu, Gross, Kajita and Rubbia gathered for a panel discussion on physics yeond the Standard Model. Photo: Ch. Flemming/Lindau Nobel Laureate Meeting

Nobel Laureates Chu, Gross, Kajita and Rubbia gathered for a panel discussion on physics beyond the Standard Model. Fabiola Gianotti from CERN joined live via video. Photo: Ch. Flemming/Lindau Nobel Laureate Meetings

 

For more pictures from #LiNo16 take a look at our Flickr-account.

 

Tweets of the day:

We want to thank all of you who engage with us on Twitter – You’re great! Here are our tweets of the day:

 

Expectations: The 66th Lindau Meeting, Africa & Space

The 66th Lindau Nobel Laureate Meeting is dedicated to physics and it will provide an opportunity for young African scientists to exchange scientific expertise and inspire cross-cultural and inter-generational encounters with other scientists. 30 Nobel Laureates and about 400 highly-talented young scientists from all over the world (almost 80 countries) will participate in the meeting that will be held in Lindau, Germany, from 26 June to 1 July 2016.

The Lindau Nobel Laureate Meetings cooperate with over 200 of the most renowned science and research institutions from over 65 countries worldwide who nominate the most qualified scientists who are then vetted by the Council for the Lindau Nobel Laureate Meetings to identify successful participants.

As an academic partner to the Lindau Nobel Laureate Meetings, the African Commission nominated 10 candidates among them the recipients of the African Union Kwame Nkrumah Young Scientist awards (laureates) and three were successful; an outcome that is expected to stimulate urge for focused scientific research and development and hence foster excellence on the continent.

The 66th meeting is happening in the wake of rising scientific activities Africa. A continental approach on harnessing the scientific strengths in the continent was developed and captured in the Science, Technology and Innovation Strategy for Africa (STISA-2024) that outlines the priorities and pillars that must be given precedence for the continent to realize the full potentials of STI’s interventions. The meeting will provide room for interactions to learn from the best practices of other regions in order to get to know specific areas of adjustments in our approach. 

 

Partaking in international space programmes could certainly change the perspective of how the West sees Africa. Image: NASA

Partaking in international space programmes could certainly change the perspective of how the West sees Africa. Image: NASA

Africa has just adopted a Space Policy and a Strategy meant to play a coordination role and in future implement various continental space programmes. Considering that most economies in the continent are in a transitional phase, miniaturized technologies that can either improve or achieve the same goals as most conventional practices, will be of much use to the continent. Small satellite technology is one of such practices on the continent. Considering that the cost of placing objects in space is determined by the weight and altitude of designated orbits, small satellites have proved to be more economical in the case of developing countries.

There are other global developments that are expected to stimulate increase in activities in space. China has just formalized its intention to develop and open its future space station to spacecraft, scientific experiments and astronauts from other countries around the world in an agreement signed with global governing body, the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS) during its annual session in Vienna on 14th June 2016. This new dimension will definitely and not only boost international cooperation in space, but also intensify on-orbit research activities from developing countries after its expected launch in 2018. Discussions of such emerging issues will benefit from the panel discussion titled “Is Quantum Technology the Future of the 21st Century?” and we expect outcomes to reflect on the African scenario.

The African Commission also runs the Pan-African University, a continental flagship programme aimed at revitalizing higher education and research in Africa and it is designed as a network of high quality African universities offering Master and Doctoral programmes to youths comprising of five thematic institutes in the five geographic regions of Africa, each concentrating on specific academic domains:

  1. 1.  Water and Energy Sciences
  2. 2.  Basic Sciences, Technology and Innovation
  3. 3.  Earth and Life Sciences
  4. 4.  Governance, Humanities and Social Sciences
  5. 5.  Space sciences

Outcomes of the panel discussion on “Future of Education in Natural Sciences” will give insight to the future orientation of education and research in natural sciences that may inform future adjustments of the programme.

Discussions will also benefit and inform future inclination of yet another flagship programme of the Commission called the AU Kwame Nkrumah Scientific Awards Programme that rewards outstanding African researchers in Earth and life Sciences and Basic Science, Technology and Innovation, and is implemented through a tripartite partnership with a view to coordinate and boost science and technology at national, regional and continental levels.

A Beautiful Quest: The Search for a Unified Theory

The search for a single overarching theory of nature that describes all the fundamental physical forces and particles has been the major thrust of modern physics. Are we about to reach this elusive goal, or is it turning into a quixotic quest that needs to be abandoned?

 

Correspondence to:

Jalees Rehman, MD

Department of Medicine and Department of Pharmacology

University of Illinois at Chicago

Email: jalees.rehman[at]gmail[dot]com

 

I shall let the little I have learnt come to light in order that someone better than I may guess the truth, and his work may demonstrate my error. At this I shall rejoice, and also because I was nevertheless a cause whereby such a truth came to light.

Albrecht Dürer (1471-1528) – Schriftlicher Nachlaß

 

How will the 20th century be remembered by the historians in the year 2525 – if man is still alive? Will the annals of history label it as the century of human suffering, in light of the millions of lives that were prematurely claimed by two world wars, countless cases of large-scale atrocities, ethnic cleansing and genocide? Or perhaps as the century in which hygiene, vaccinations and antibiotics helped save millions of lives, subjugated colonies gained independence from their oppressors and in which the majority of countries finally recognized women as full citizens, granting them the right to vote and reproductive control over their own bodies?

Considering that the 20th century ended less than two decades ago, any attempt to ascertain what will be deemed significant in the coming centuries would be pure speculation. Nevertheless, when we reflect on what we believe most important about centuries past, it becomes rather obvious what aspects of history leave a long-lasting imprint on the collective consciousness of subsequent generations: expressions of human ingenuity. In school, we may have memorized the dates of when wars started and ended, but we are enthralled by the beauty and insights emanating from the great works of art, music, literature, philosophy and science of centuries past. Testaments to human ingenuity, tenacity and the pursuit of beauty and justice include the development of vaccines and antibiotics, abandoning colonialism and granting equality to women. But there is another, far less known front-runner for the most important intellectual accomplishment in the 20th century: The Standard Model. It is also a shoo-in for the “Most Understated-Name-Ever Award.” What is the Standard Model, and why is it a pinnacle of human achievement?

The Standard Model is to date the most comprehensive and experimentally validated theory of the fundamental physical forces and elementary particles in nature. It unifies three core physical forces, the electromagnetic force, the strong force and the weak force, and describes fermions – elementary “substance” particles, such as quarks, electrons and neutrinos – as well as bosons – elementary “force” particles, such as photons, gluons and the Higgs boson. As such, the Standard Model allows us to understand the very nature of energy and matter and provides a framework for understanding the universe. The Standard Model was finalized in the 1970s, but it is built on some of the conceptual revolutions in physics at the beginning of the 20th century, such as quantum mechanics and the theory of special relativity which challenged traditional views of determinism, time and space.

While there have been many important scientific developments in the past century, the Standard Model stands out as a prime example of how theoretical science and experimental science work like intercalating cogwheels, propelling each other forward. The theoretical framework was formulated in the 1970s based on prior experimental data, but it made definitive predictions regarding the existence of particles that had never been observed. And each subsequent decade, experiments undertaken to test its validity confirmed its predictions, such as the discovery of the top quark in 1995, the tau neutrino in 2000 and the Higgs boson in 2012/2013. This unprecedented pace of experimental testing and theoretical formulation of the Standard Model could only be achieved by the collaborative efforts of thousands of physicists, transcending boundaries of nationality, gender and ideology and united by their common goal of uncovering the fundamental laws of nature.

The Standard Model is part of a grander quest in physics to develop unified theories with the ultimate goal to have one final Unified Theory, which is sometimes referred to as the “Theory of Everything” – quite a baptismal contrast to the humility exuded by the name “Standard Model.”

 

Photo: iStock.com/Courtney Keating

Quixotic or not, mankind’s quest to find a unified theory governing all the innermost principles of nature certainly yielded a greater understanding of the beauty of our world along the way. Photo: iStock.com/Courtney Keating

George Smoot is Professor of Physics at the University of California, Berkeley, the Founding Director of the Berkeley Center for Cosmological Physics and received the Nobel Prize for Physics in 2006 for his work on cosmic microwave background radiation. Smoot suggests that the unification of forces and concepts has been the major thrust of modern physics. This applies to the conceptual combining of mechanical classical physics and statistics to produce statistical mechanics, which formed the foundations of thermodynamics. The Standard Model also arose from a tradition of stepwise unifications, such as the classic unification of electricity and magnetism into electromagnetism by Maxwell in the 19th century. That was followed by the development of a theory that unified weak and electromagnetic forces in the second half of the 20th century and the Standard Model, which also included the strong force.

“There has long been a goal to include Gravity and make a more unified theory, which is sometimes referred to the Theory of Everything even though we now know that there must be or likely are some additional forces such as dark energy,” says Smoot.

Despite its successes, the Standard Model also has its limitations, and among its most important limitations is that it does not include gravity – the fourth of the fundamental physical forces – and that it also does not account for dark matter and dark energy, hypothesized forms of energy and matter that are thought to form the bulk of mass and energy in the universe and that explain key cosmological phenomena, such as the expansion of the universe.

 

George during his 2010 lecture at Lindau. Photo: Ch. Flemming/Lindau Nobel Laureate Meeting

George during his 2010 lecture at Lindau. Photo: Ch. Flemming/Lindau Nobel Laureate Meeting

Gravity is currently best described by the Theory of General Relativity, developed by Albert Einstein in the first half of the 20th century, which replaced Newton’s theory of gravity. Like the Standard Model, the Theory of General Relativity has been repeatedly tested and confirmed by experimental observations. It is also one of the most beautiful theories in physics. Steven Weinberg, who received the 1979 Nobel Prize in Physics together with Abdus Salaam and Sheldon Lee Glashow for their pioneering work in the development of the Standard Model, has described the beauty of General Relativity in his book Dreams of a Final Theory. Weinberg admits that one cannot precisely define what constitutes “beauty” in physics, but one key characteristic of a beautiful scientific theory is the simplicity of the underlying concepts. Despite the appearance of greater mathematical complexity in Einstein’s theory, Weinberg considers it more beautiful than Newton’s theory because the Einsteinian approach rests on one elegant and simple principle – the equivalence of gravitation and inertia. A second characteristic for beautiful scientific theories is inevitability. Every major aspect of a beautiful theory appears so perfect that it cannot be tweaked or improved on. Any attempt to significantly modify Einstein’s Theory of General Relativity would undermine its fundamental concepts, just like any attempts to move around parts of Raphael’s Holy Family would weaken the whole painting.

According to Weinberg, the final unified theory would not only comprise all fundamental physical forces but it would also embody beauty. This quest for unity and beauty may seem like an anachronism, perhaps even quixotic, considering that even after decades of tireless efforts by the world’s most brilliant physicists, it has not yet been possible to combine General Relativity and the Standard Model into a beautiful Unified Theory. Does this mean that it is time to abandon this quest and just accept the fact that there may be multiple distinct theories, such as General Relativity and the Standard Model that are all independently valid? Not according to many of the world’s leading physicists.

Smoot explains, “There are deep underlying reasons and symmetries that make us think that the unification of the forces is not only a beautiful and powerful construct but also necessary to the completeness of Physics.”

 

Steven Weinberg (right) with students at the Lindau Meeting in 1982. Photo: Archive Böcher/Lindau Nobel Laureate Meetings

Steven Weinberg (right) with students at the Lindau Meeting in 1982. Photo: Archive Böcher/Lindau Nobel Laureate Meetings

sixnamesofbeauty

Source: Crispin Sartwell “Six Names of Beauty”

How does the concept of beauty in physics relate to other forms of beauty that we experience around us? Beauty in art, music, or literature often manifests itself as a desire of the audience to keep looking, listening, or reading. This form of beauty evokes a desire or longing in its audience. The philosopher Crispin Sartwell explored words for “beauty” used in six different languages, thus illuminating various aspects of beauty across cultures and languages. In his book Six Names of Beauty, Sartwell offers us the following words used to describe beauty and their approximate translations into English:

None of these words is necessarily the exclusive word used for beauty in any given language but it suggests that certain languages can emphasize distinct facets of beauty. A multi-lingual perspective may also help us discover our own deeper concepts of beauty as we find parallel concepts in other languages that may not be readily apparent. A native English speaker, for example, can easily relate “beauty” to light, harmony, wholeness and nobility but a deeper meditation may reveal that humility and imperfection are also aspects of beauty.

A concept of beauty which encompasses beauty, yapha, sundara, to kalon, wabi-sabi, hozho and the thousands of additional words used in other languages make it easier to understand that beauty in physics and beauty in art may be quite similar. The Unified Theory will represent a form of wholeness or completeness of the fundamental laws of physics, it will describe the harmony and balance between particles and forces, it will be expressed in the simplest possible terms, it is an ideal that scientists are striving towards and they hope that it will illuminate the fundamental mysteries of physics.

Frank Wilczek is the Herman Feshbach Professor of Physics at the Massachusetts Institute of Technology and received the 2004 Nobel Prize in Physics together with David Gross and David Politzer for their seminal work on the nature of the strong force. In addition to his work as one of the world’s leading theoretical physicists, Wilczek is actively engaged in communicating the core concepts of physics to a non-specialist audience via his website and several books. His most recent book, A Beautiful Question, is a profound exploration of the physics, aesthetics and philosophy surrounding the search for the Unified Theory. He also replaces the title Standard Model with the more appropriate term Core Theory. He avoids the hyperbolic and misleading expression “Theory of Everything” and instead points out that the Core Theory is a perpetual work in progress, continuously striving for greater beauty and unity. He is optimistic that in the near-future, the Core Theory will be able to accommodate the electromagnetic, weak, strong and gravitational forces as well as describe dark energy and dark matter.

One of the routes that Wilczek maps out for the evolution of the Core Theory is supersymmetry, the idea that when “force” particles (bosons) move into quantum dimensions, they become “substance” particles (fermions) and vice versa. This expanded (“super”) symmetry between bosons and fermions posits the existence of novel superpartner particles. Quarks and leptons, for example, would have squarks and sleptons as their hypothetical boson superpartners. Gauginos, on the other hand, would be hypothetical fermion superpartners of gauge bosons. The elegance and beauty of this model is that it would offer the possibility of including gravity in a possible unified Core Theory that includes hypothetical gravitons and their equally hypothetical superpartner gravitinos. One of the challenges of uniting all four forces is that gravity is by far the weakest of all the physical forces. But supersymmetry and the presence of the hypothesized superpartners, suggests that there exist certain high energy levels at which the different forces begin to approximate each other. Wilczek states that this would still not represent the complete unification of the forces, but it could be a major first step. However, Wilczek also clearly explains that the experimental evidence for supersymmetry and the hypothesized superpartner particles is lacking. The Large Hadron Collider (LHC) at CERN in Geneva that experimentally validated the Higgs boson in 2012/2013 may need to significantly ramp up its energy to generate these particles.

 

The search Supersymmetry is still going on at CERN. Photo: D. Dominguez/CERN

The search Supersymmetry is still going on at CERN. Photo: D. Dominguez/CERN

Another path toward a Unified Theory that is being actively pursued by theoretical physicists is string theory, also referred to as superstring theory and M-theory in its later iterations. A brief introduction to the concepts of string theory can be found in The Grand Design by Stephen Hawking and Leonard Mlodinow, and a far more comprehensive one is in The Fabric of the Cosmos by Brian Greene. Through string theory, these physicists are also able to achieve some degree of a unification of the fundamental forces on a theoretical level, but they invoke the presence of nine spatial dimensions (string theory) or even ten spatial dimensions (M-theory) in addition to one time dimension. Proponents of string theory view it as a major conceptual revolution of our concept of time and space, likening it to the paradigm shifts in our concepts of space, time and causality that were triggered by the theories of relativity and quantum mechanics one century ago.

However, there is one key difference that sets apart string theory from the theories of relativity and quantum mechanics. Even though the latter changed our view of the world, they did not fundamentally alter how we pursue science. Successful science always combines theories with empirically-testable hypotheses and predictions. Quantum mechanics, the special theory of relativity, the general theory of relativity and the Standard Model have all been validated by experiments. Supersymmetry has not yet been experimentally validated, but it makes claims that could be eventually be tested and confirmed if the proposed superpartner particles are found at the LHC. However, it is difficult to even conceive of experiments that could prove the existence of nine or ten spatial dimensions. A string of critical books has recently been published that attack string theory on its lack of clearly defined hypotheses and predictions that would allow for its experimental validations. Farewell to Reality by Jim Baggott, Not Even Wrong by Peter Woit and The Trouble with Physics by Lee Smolin question whether a theory without experimental validation can even be considered scientific or whether it has begun taking on the feature of a religious dogma.

To a certain extent, similar criticisms can also be brought forward against supersymmetry since there is no definitive experimental proof to back it up, just circumstantial evidence as described by Wilczek in A Beautiful Question. One response to critics of supersymmetry is that the proposed superpartner particles are so rare and require such high energy to generate that we may not yet have the necessary technology to even test the theory. The Higgs particle, for example, was predicted by the Standard Model several decades before the LHC was able to confirm its existence. It is therefore quite possible that the LHC will find evidence for supersymmetry in the next years as the energy levels are ramped up. But at what point does one abandon a scientific idea or theory as not validated by experiments, and how long does one continue to test it? And at what point does clinging to ideas that have not or cannot be experimentally validated become non-scientific? The search for the Unified Theory has raised profound questions not only about the nature of matter and energy but also the definition of science and the scientific methodology.

I recently asked Frank Wilczek whether he felt that supersymmetry is still a prime candidate for a Unified Core Theory:

I’m still optimistic about ‘low-energy,’ i.e. accessible, supersymmetry, since the circumstantial case for it is very strong. The Large Hadron Collider (LHC) will have a good shot at it in the next few years. So far they haven’t seen any direct positive evidence, however, which has been disappointing for many people. For a long time, I’ve been worried that the LHC might not have quite enough energy for the job.

Wilczek believes that the current energy levels at the LHC may be able to generate gauginos, the superpartners of gauge bosons, but that the generation of squarks and sleptons may require higher levels of energy. Wilczek agrees that the testability and experimental validation of supersymmetry is essential for it to become part of a Unified Core Theory. For Wilczek, experimental testability is an essential part of a theory’s beauty. A Unified Theory also needs to address other important issues that are not yet resolved by General Relativity and the Standard Model, such as the question of dark matter and dark energy.

Unified Theories’ that do not address these questions in a satisfying way don’t deserve the name. String theory, in particular, falls short. (Frank Wilzek)

Does one need string theory or M-theory to develop a Unified Theory?

Wilczek is convinced we can make important progress at present without string theory or M-theory but cannot rule out that they may prove crucial in the long run. “They have a lot of potential, but they haven’t yet proved themselves to be essential parts of the description of Nature. It’s not clear, at least to me, what problems they’ll solve, or even what they are exactly.”

Wilczek also points out that there are several other exciting questions in physics that will attract the next generation of physicists, some of which he recently outlined in an article “Physics in 100 years.” The search for a Unified Theory, the validation of supersymmetry and understanding dark matter or dark energy will be complemented by great discoveries in gravitational wave astronomy, quantum computation and many other areas of research.

This also relates to an important point made by the Nobel Laureate Robert Laughlin in his book A Different Universe. An excessive focus on identifying the elementary forces and particles brings about a culture of extreme reductionism, assuming that the whole universe can be explained by knowing the building blocks. Taking apart a Lego sculpture and then laying out all the colored Lego bricks in front of us does not really tell us much about the beauty and splendor of the sculpture. Laughlin hopes and predicts that the Age of Reductionism will soon be replaced by an Age of Emergence in which the focus gradually shifts toward understanding how complex structures arise from the fundamental particles and atoms identified during the Age of Reductionism. Just like the simplicity of reductionism, the complexity of emergence also embodies beauty. Instead of heralding the end of physics (as is implied in expressions such as “Theory of Everything”), Unified Theories are just a starting point for the more complex questions in physics.

 

Our ancestors left us awe-inspiring monuments whose grandeur never has been replicated so far. Our own legacy to future generations however, may consist of something more sublte yet fundamental: A profound understanding of the universe's inner workings. Photo: iStock.com/DKart

Our ancestors left us awe-inspiring monuments of never replicated grandeur. Our own legacy to future generations however, may consist of something more subtle yet substantially fundamental: A profound understanding of the universe’s inner workings. Photo: iStock.com/DKart

The evolving Core Theories of physics exemplify the human intellect and spirit and have challenged our perceptions of reality. We often marvel at the splendor of palaces and monuments, but the enduring legacy of any civilization can be found in its ideas. While all the seven wonders of the ancient world have crumbled except for the pyramids of Giza, many of the ideas of ancient scholars have survived, and their magnificence continues to inspire us even after millennia. Even though the great discoveries in physics were often spearheaded by few scientists, they ultimately represent a collaborative effort of several thousands of scientists who worked together to experimentally validate theories and, to a larger extent, also a conjoined effort of all humankind who directly or indirectly contribute to these efforts, perhaps even by allowing public funding to support the heroic struggles.

If we want to establish a legacy of our civilization that truly matters to our future descendants, it will not be achieved by erecting huge monuments but by expanding efforts to find simple and complex beauty in our universe. The past century of basic research in physics has been among the most fruitful periods in the history of any science, but it has also reminded us that we need to invest resources and provide continuing support for it to thrive. The universality of natural laws and the spirit of scientific collaboration across cultural and political boundaries may ultimately serve as a model for a more peaceful human co-existence. In a world that is too often polarized by political and religious ideologies, the search for a unified theory of the fundamental physical forces encapsulates the greater human quest for beauty. We may not always agree on what constitutes beauty but humans in all cultures are united in their longing for beauty. The arduous pursuit of beauty itself embodies beauty and is an opportunity for all humankind to share in the joy of this journey.