Kelly McSweeney

Nov 14th 2018

This Quantum Discovery Expands Our Concept of Time


The newest scientific discoveries behind quantum communication and quantum computing could alter our entire concept of time. A recent experiment uses a device called a quantum switch to jumble up a sequence of two events so that there is no “before” or “after,” because they take place in both orders simultaneously.

Which Came First, the Chicken or the Egg?

Oddly enough, in the world of quantum physics, the chicken and the egg can both come first, according to a press release about the quantum switch from the University of Queensland published in Science Daily.

Dr. Jacqui Romero explained, “The weirdness of quantum mechanics means that events can happen without a set order.”

The team of physicists demonstrated that quantum mechanics allows events to occur with no definite causal order — in other words, without the cause-and-effect sequence that we typically expect for multiple events over time.

The Light-Bending (and Mind-Bending) Experiment

ScienceNews explained that in the experiment, the researchers used a quantum switch to prove that the order of events — in this case, changing the shape of light one way or another — occurs simultaneously. They used a polarizing beam splitter to send particles of light (photons) through a series of two operations (labeled “A” and “B”). The photons can travel along two separate paths, which depends on polarization, a term that describes whether its electromagnetic waves wiggle horizontally or vertically.

Horizontal polarization makes operation “A” happen first, while vertical polarization means that “B” will happen first. However, a phenomenon called superposition allows a photon to be both horizontally and vertically polarized at the same time, which also means that the photon experiences “A” and “B” at the same time.

“‘This is just a first proof of principle, but on a larger scale indefinite causal order can have real practical applications, like making computers more efficient or improving communication,'” researcher Dr. Fabio Costa said in the press release.

Philosophical and Practical Applications

The new quantum switch could also eventually be used for two emerging technologies: quantum communication and quantum computing. According to ScienceNews, the quantum switch could someday be used to encode and decode information on a quantum network. Although the data would be appear to be scrambled, superposition would allow for some information to be extracted.

Superposition is also the reason people are so excited about quantum computing. According to Wired, even though quantum computing was first suggested in 1982, the concept has only recently started to become reality. Today’s computers represent bits of data as 1 or 0, but in a quantum computer, they can also be both at the same time.

Experiments like the new quantum switch, and studying quantum mechanics in general, can help redefine our concept of time. Theoretical physicist and philosopher Carlo Rovelli wrote a new book, “The Order of Time,” which explores this idea. Rovelli told Science, “Time is not a single notion; it is multifaceted, and to study it scientifically, we must disentangle it.”

According to Rovelli, our macroscopic perspective as humans blurs our view of the world. He added, “‘The distinction between past and future is tied to this blurring and would disappear if we were able to see the microscopic molecular activity of the world.'”

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