Quantum (量子) computers have been on my mind a lot lately. A friend has been sending me articles on how quantum computers might help solve some of the biggest challenges we face as humans. I've also had exchanges with two quantum-computing experts. One is computer scientist Chris Johnson who I see as someone who helps keep the field honest. The other is physicist Philip Taylor.

For decades, quantum computing has been little more than a laboratory curiosity. Now, big tech companies have invested in quantum computing, as have many smaller ones. According to Business Weekly, quantum machines could help us "cure cancer, and even take steps to turn climate change in the opposite direction." This is the sort of hype (炒作) that annoys Johnson. He worries that researchers are making promises they can't keep. "What's new," Johnson wrote, "is that millions of dollars are now potentially available to quantum computing researchers.

As quantum computing attracts more attention and funding, researchers may mislead investors, journalists, the public and, worst of all, themselves about their work's potential. If researchers can't keep their promises, excitement might give way to doubt, disappointment and anger, Johnson warns. Lots of other technologies have gone through stages of excitement. But something about quantum computing makes it especially prone to hype, Johnson suggests, perhaps because ""quantum' stands for something cool you shouldn't be able to understand." And that brings me back to Taylor, who suggested that I read his book Q for Quantum.

After I read the book, Taylor patiently answered my questions about it. He also answered my questions about PyQuantum, the firm he co-founded in 2016. Taylor shares Johnson's concerns about hype, but he says those concerns do not apply to PyQuantum.

The company, he says, is closer than any other firm "by a very large margin (幅度)" to building a "useful quantum computer, one that "solves an impactful problem that we would not have been able to solve otherwise." He adds, "People will naturally discount my opinions, but I have spent a lot of time quantitatively comparing what we are doing with others"

Could PyQuantum really be leading all the competition "by a wide margin", as Taylor claims? I don't know. I'm certainly not going to advise my friend or anyone else to invest in quantum computers. But I trust Taylor, just as I trust Johnson.

"What would the world be if there were no hunger?" It's a question that Professor Crystal would ask her students. They found it hard to answer, she wrote later, because imagining something that isn't part of real life—and learning how to make it real—is a rare skill. It is taught to artists and engineers, but much less often to scientists. Crystal set out to change that, and helped to create a global movement. The result一an approach known as systems thinking—is now seen as essential in meeting global challenges.

Systems thinking is crucial to achieving targets such as zero hunger and better nutrition because it requires considering the way in which food is produced, processed, delivered and consumed, and looking at how those things intersect (交叉) with human health, the environment, economics and society. According to systems thinking, changing the food system—or any other network- requires three things to happen. First, researchers need to identify all the players in that system, second, they must work out how they relate to each other, and third, they need to understand and quantify the impact of those relationships on each other and on those outside the system.

Take nutrition. In the latest UN report on global food security, the number of undernourished (营养不良) people in the world has been rising, despite great advances in nutrition science. Tracking of 150 biochemicals in food has been important in revealing the relationships between calories, sugar, fat and the occurrence of common diseases. But using machine learning and artificial intelligence, some scientists propose that human diets consist of at least 26,000 biochemicals—and that the vast majority are not known. This shows that we have some way to travel before achieving the first objective of systems t hinking - which,in this example, is to identify more constituent parts of the nutrition system.

A systems approach to creating change is also built on the assumption that everyone in the system has equal power. But as some researchers find, the food system is not an equal one. A good way to redress (修正) such power imbalance is for more universities to do what Crystal did and teach students how to think using a systems approach.

More researchers, policymakers and representatives from the food industry must learn to look beyond their direct lines of responsibility and adopt a systems approach. Crystal knew that visions alone don't produce results, but concluded that "we'll never produce results that we can't envision".

My name is Alice. Early last year, I was troubled by an anxiety that crippled (削弱) my ability to do anything. I felt like a storm cloud hung over me. For almost a year I struggled on, constantly staring at this wall that faced me. My perfectionist tendencies were the main root of this: I wanted to be perfect at whatever I did, which obviously in life is not possible, but it consumed me.

One day, I attended a presentation by wildlife conservationist Grant Brown at my high school. His presentation not only awed and inspired me, but also helped emerge an inner desire to make a difference in the world. I joined a pre-presentation dinner with him and that smaller setting allowed me to slowly build up my courage to speak one-on-one with him- an idea that had seemed completely impossible. This first contact was where my story began.

A month later, Brown invited me to attend the World Youth Wildlife Conference. Looking back, I now see that this would be the first in a series of timely opportunities that my old self would have let pass, but that this new and more confident Alice enthusiastically seized. Shortly after I received his invitation, applications to join the Youth for Nature and the Youth for Planet groups were sent around through my high school. I decided to commit to completing the applications, and soon I was a part of a growing global team of young people working to protect nature. Each of these new steps continued to grow my confidence.

I am writing this just six months since my journey began and I've realised that my biggest obstacle (障碍) this whole time was myself. It was that voice in the back of my head telling me that one phrase that has stopped so many people from reaching their potential: I can't. They say good things come to those who wait, I say: grab every opportunity with everything you have and be impatient. After all, nature does not require our patience, but our action.