A thousandfold magnification of a smudge, and suddenly it does not seem to play by the same rules anymore. For example, the outline does not look good most of the time and resembles a diffuse, sprawling cloud. This is the bizarre field of quantum mechanics. "Some books say that a particle is in different places at the same time," says physicist Markus Arndt from the University of Vienna in Austria. "Whether that really happens is a matter of interpretation."
Another way of saying it: Quantum particles sometimes seem like waves spreading in space. They can back into each other and even to themselves. However, when you encounter this wavy object with certain instruments, or when the object interacts with neighboring particles in a certain way, it loses its wavy properties and behaves like a discrete point ̵
From which size are quantum effects no longer valid? How big can something be and still behave like a particle and a wave? The physicists had difficulty answering this question because the experiments were hard to design.
Now, Arndt and his team have bypassed these challenges and observed quantum-wave-like properties on the largest objects to date – molecules of 2,000 atoms. the size of some proteins. The size of these molecules exceeds the previous record by two and a half times. To see this, they injected the molecules into a 5-meter-long tube. When the particles hit a target at the end, they do not just end up as randomly scattered dots. Instead, they formed an interference pattern, a stripe pattern of dark and light stripes, suggesting that waves collide and connect. They published the work today in Natural Physics .
"It's surprising that this works at all," says Timothy Kovachy of Northwestern University, who was not involved in the experiment. It's an extremely difficult experiment, he says, because quantum objects are sensitive and suddenly change from a wavelike to a particulate state through interactions with their environment. The larger the object, the more likely it is to hit something, heat up, or even break apart, causing these transitions. In order to keep the molecules in a wave-like state, the team grants them a narrow path through the tube, as if the police were blocking a parade. They hold the tube in a vacuum and prevent the smallest wobble of the entire instrument through a system of springs and brakes. The physicists then had to carefully control the speed of the molecules so they would not overheat. "It's really impressive," says Kovachy.