Noble prize in physics 2023

 

Some processes in physics happen in the blink of an eye, while others happen in the blink of a photon. This year’s Nobel Prize in Physics was awarded to Pierre Agostini of the Ohio State University, Ferenc Krausz of the Max Planck Institute of Quantum Optics in Garching, Germany, and Anne L’Huillier of Lund University in Sweden for developing the field of ultrafast laser pulses. L’Huillier is only the fifth woman to have ever won the Nobel Prize in Physics.

These pulses are on the scale of the attosecond—a billionth of a billionth of a second. This duration is so short that there are as many attoseconds in a single second as there have been seconds in the entire history of the universe. This year’s prize was awarded “for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter.”

“Attosecond science allows us to address fundamental questions,” said Eva Olsson, chair of the Nobel Committee for Physics, at a press conference today. At the atomic level, the motions of electrons and nuclei typically take place over the course of attoseconds. In the late 19th century early photographers made use of cameras to determine whether a horse took all of its hooves off the ground at a gallop—a process too fast for the human eye to discern. (Spoiler: horses do completely leave the ground.) Today’s researchers hope to do the equivalent at attosecond timescales by using ultrafast lasers to get clearer views of otherwise blurry atomic processes.

But generating light in extremely short pulses is not easy. For many years light pulses were stuck in the femtosecond regime (one femtosecond is 1,000 attoseconds). That’s good enough to resolve molecules in chemical reactions, a feat that won the 1999 Nobel Prize in Chemistry—but it’s insufficient to spot the zigging and zagging of speedier electrons.

L’Huillier broke down some of the first barriers in 1987, when she discovered that passing an infrared laser through a noble gas, such as argon, led to a pattern in the emitted light: a plateau in the frequency. This plateau would prove vital for work done in the early 2000s, when Agostini created multiple 250-attosecond-long pulses of light while Krausz, working independently, generated single 650-attosecond-long pulses.

With the newfound probes developed by Agostini, Krausz and L’Huillier, researchers can now generate laser pulses of merely a few dozen attoseconds. Further refinements of these techniques to generate ever shorter pulses promise to deepen scientists’ understanding of electron dynamics and could lead to breakthroughs in medical diagnostics, as well as the development of novel semiconductors.

As usual, the award came as a surprise to its recipients. When L’Huillier was notified, she was in the middle of giving a lecture and missed the first few calls from Stockholm. After stepping outside to take the call, she returned to the lecture where she continued teaching without telling her students anything. “Teaching is very, very important. For me, it’s very important,” she told Hans Ellegren, secretary-general of the Royal Swedish Academy of Sciences, over the phone during the prize’s announcement.

A brief history of electric current

 Have you ever wondered how electricity works? From the flick of a switch to the hum of a computer, electric current powers so much of our daily lives. But how did we figure out how to harness this mysterious force?

Believe it or not, the story of electric current begins all the way back in ancient Greece. The Greeks discovered that rubbing amber against fur could create a static charge, which was the first inkling that electricity existed.

Fast forward a few thousand years to the 17th century, when scientists like Benjamin Franklin started to study electricity in earnest. Franklin is best known for his experiment with a kite and a key, which showed that lightning was a form of electricity.

But it wasn't until the 19th century that things really started to heat up in the world of electricity. Enter Alessandro Volta, an Italian scientist who invented the first battery. This was a big deal, because it allowed scientists to create a continuous flow of electric current.

Next up was Hans Christian Oersted, a Danish physicist who discovered that an electric current could create a magnetic field. This discovery led to the development of the first electromagnet, which was a big step towards harnessing electricity for practical purposes.

And the hits just kept on coming. In 1831, Michael Faraday, an English scientist, discovered electromagnetic induction, which forms the basis of the modern generator. This allowed us to create large amounts of electricity and distribute it over long distances.

In the 1870s, James Clerk Maxwell, a Scottish physicist, formulated the equations of electromagnetism, which described the behavior of electric and magnetic fields. This was a huge breakthrough, because it allowed us to understand how electricity and magnetism are related.

Fast forward to the 20th century, and we get into some really mind-bending stuff. Scientists discovered the electron, which is a tiny particle that carries electric charge. And they developed quantum mechanics, which is a way of understanding the behavior of particles on a very small scale.

Today, electric current powers pretty much everything we do. From the lights in our homes to the devices in our pockets, we rely on electricity to get through the day. The story of electric current is a story of human ingenuity, curiosity, and a relentless drive to understand the world around us. So the next time you turn on a light or charge your phone, remember that you're participating in a centuries-long journey of discovery and innovation.

Quantum entanglement

In quantum physics, the entanglement of particles describes a relationship between their fundamental properties that can't have happened by chance. This could refer to states such as their momentum, position, or polarisation.

Knowing something about one of these characteristics for one particle tells you something about the same characteristic for the other.

Think of a pair of gloves. If you found a right glove alone in your drawer, you can be certain the missing glove would fit your left hand. The two gloves could be described as entangled, as knowing something about one would tell you something important about the other that isn't a random feature.

In fashion, this concept isn't all that strange. But the concept poses a problem for quantum mechanics.

Does quantum entanglement work with 'reality'?

The physicists Niels Bohr and Werner Heisenberg argued an object's state only truly existed once it became associated with a measurement, which meant somebody needed to observe it experimentally. Until then, its nature was merely a possibility.

To other physicists, such as the famous Albert Einstein and Erwin Schrödinger, this was as preposterous as saying a cat inside a box is neither alive nor dead until you look.

Finally two physicists Boris Podolsky and Nathan Rosen collaborated with Einstein to come up with a thought experiment, where two objects interact in some way.

By measuring one of them, we might be able to work out some of its partner details without needing to measure it directly, thanks to its 'entangled' history.

"Spooky action at a distance"

In response to this dilemma (now called the EPR or Einstein-Podolsky-Rosen paradox) Bohr suggested that the state of both objects simply became 'real' at the same time, as if they instantly swapped details on this experimental intrusion across a distance.

Einstein dismissed this idea as a 'spooky action', claiming on multiple occasions that "God does not play dice".

Decades later, Bohr's ideas still stand strong, and the strange nature of quantum entanglement is a solid part of modern physics. Physics really is fundamentally 'spooky' after all.