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.

    Look to many of history's cultural symbols, and there you'll find an ancestor of Frosty, the snowman in the movie Frozen. It appeared on some of the first postcards, starred in some of the earliest silent movies, and was the subject of a couple of the earliest photos, dating all the way back to the 1800s. I discovered even more about one of humanity's earliest forms of life art during several years of research around the world.

    For example, snowmen were a phenomenon in the Middle Ages, built with great skill and thought. At a time of limited means of expression, snow was like free art supplies dropped from the sky. It was a popular activity for couples to leisurely walk through town to view the temporary works of chilly art. Some were created by famous artists, including a 19-year-old Michelangelo, who in 1494 was appointed by the ruler of Florence, Italy, to build a snowman in his mansion's courtyard.

    The Miracle of 1511 took place during six freezing works called the Winter of Death. The city of Brussels was covered in snowmen—an impressive scene that told stories on every street corner. Some were political in nature, criticizing the church and government. Some were a reflection of people's imagination. For the people of Brussels, this was a defining moment of defining freedom. At least until spring arrived, by which time they were dealing with damaging floods.

    If you fear the heyday of the snowman has passed, don't worry: I've learned that some explosive snowman history is still being made today. Every year since 1818, the people of Zurich, Switzerland, celebrate the beginning of spring by blowing up a snowman. On the third Monday of April, the holiday Sechselauten is kicked off when a cotton snowman called the Boogg is stuffed with explosive and paraded through town by bakers and other tradesmen who throw bread to the crowds. The parade ends with the Boogg being placed on a 40-foot pile of firewood. After the bells of the Church of St. Peter have rung six times, representing the passing of winter, the pile is lit. When the snowman explodes, winter is considered officially over—the quicker it is burnt down, the longer summer is said to be.

Sometime in the early 1960s, a significant thing happened in Sydney, Australia. The city discovered its harbor. Then, one after another, Sydney discovered tots of things that were just sort of there-broad parks, superb beaches, and a culturally diverse population. But it is the harbor that makes the city.

Andrew Reynolds, a cheerful fellow in his early 30s, pilots Sydney ferryboats for a living. I spent the whole morning shuttling back and forth across the harbor. After our third run Andrew shut down the engine, and we went our separate ways-he for a lunch break, I to explore the city.

"I'll miss these old boats," he said as we parted.

"How do you mean?" I asked.

"Oh, they're replacing them with catamarans. Catamarans are faster, but they're not so elegant, and they're not fun to pilot. Hut that's progress, I guess."

Everywhere in Sydney these days, change and progress are the watchwords（口号）, and traditions are increasingly rare. Shirley Fitzgerald, the city's official historian, told me that in its rush to modernity in the 1970s, Sydney swept aside much of its past, including many of its finest buildings. "Sydney is confused about itself," she said. "We can't seem to make up our minds whether we want a modern city or a traditional one. It's a conflict that we aren't getting any better at resolving（解决）.”

On the other hand, being young and old at the same time has its attractions. I considered this when I met a thoughtful young businessman named Anthony. "Many people say that we lack culture in this country," he told me. "What people forget is that the Italians, when they came to Australia, brought 2000 years of their culture, the Greeks some 3000 years, and the Chinese more still. We've got a foundation built on ancient cultures but with a drive and dynamism of a young country. It's a pretty hard combination to beat."

He is right, but I can't help wishing they would keep those old ferries.