Scientists Built a Radical Information Engine That Harnesses Molecular Energy
Scientists used a laser to trap a bead in water, making an information engine.
As the bead moves, the tweezers adjust and track its position, creating an information trail.
The smallest units of information are simple on and off “bits,” like electrical pulses.
In new research, scientists have reviewed a special type of abstract engine that works by holding a microbead in a drop of water using an optical trap. This construction uses the energy that runs through our universe on the nano level to make movements and convey information—partly as an illustration that such things are even possible, and partly as the continuation of a thought exercise that dates back a century or more. It sounds like we need more information about information engines.
Researchers from Simon Fraser University in British Columbia, Canada, collaborated on a paper that appears in the journal Advances in Physics: X. It’s a detailed breakdown of a complete machine. “Our engine, an optically trapped bead, converts energy from favorable fluctuations of a heat bath into directed motion, thereby storing gravitational potential energy,” the researchers wrote.
The bead is held in a heat bath by optical tweezers—a heat bath is a large body of water or other material that can hold a consistent temperature no matter how much of that heat is removed by something like an attached engine, while optical tweezers are really a laser that pins a microscopic object using the attraction or repulsion of laser light particles. So, energy from the heat bath causes the bead to move a certain limited amount within the range of the optical tweezers, and the heat bath itself is not diminished.
As the bead moves, the optical tweezers follow and retighten on the bead’s new position. What results is a kind of dowsing rod effect for a specific kind of information. The bead’s moving position demonstrates its speed and how much energy is being captured and used by the bead. This is the “information” of the information engine, and while this kind of engine is newly possible because of technologies like the optical tweezers, the idea is from more than a century ago.
If the term “information” feels foreign here, that’s understandable, but micro-level information like this is actually all around us. Our laptops and smartphones are highly constructed and abstracted to the point where the information in them is in binary 0s and 1s. But a computer chip is not pressing a button labeled “0” or “1” on some imagined keypad—the signals are electric pulses that last a millionth of a second.
Like Morse code, these pulses arrange themselves into user-friendly patterns—step by step, and with a lot of decoding. And that’s not all that different (on a basic level) from the information engine described in the Simon Fraser University research. When the energy in a particle causes it to move a certain distance and in a certain direction, that’s a piece of information in the same way an electrical impulse meaning “0” or “1” is a piece of information.
And all that information can eventually power an information engine, a concept that can be traced back to an idea first written down by Scottish physicist James Clerk Maxwell in 1867. He imagined a system where some controlling being could allow certain molecules in and keep certain molecules out, which would violate the second law of thermodynamics. This became known as Maxwell’s Demon—the demon is the one letting particles in and out of the hot and cool chambers.
Maxwell didn’t mean this as anything more than a thought exercise, and, of course, the Simon Fraser University team isn’t breaking any laws of the universe. But setups like Maxwell described are referred to as information engines, and they’ve become more and more plausible as scientists have invented new ways to manipulate molecules and other micro-scale matter. In this particular experimental setup, the parts aren’t that different from a quantum computer.
So, what does this all really mean? Well, information engines will continue to develop, because no scientist can say no to some optical tweezers and a heat bath now that we have them. But it could be that studying molecules in this type of setup can help us understand molecular processes in our bodies and the world around us. Inside our cells, chemical bonds break and reform, molecules are separated to release their energies, and our biological processes rely on these reactions.
It could even be that our bodies have evolved processes that take advantage of how physics naturally creates shorter paths, meaning less work and less calories and other outside energy required by out bodies. Who knows what surprising microscopic fact could finally illuminate exactly how we tick?
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