With the help of a little alcohol, scientists have discovered supposedly impossible chemical reactions in the cold reaches of space. Organic molecules like methanol are being created and destroyed in clouds of interstellar gas, thanks to a spooky process called quantum tunneling.
The findings, published in Nature Chemistry, reveal a mind-boggling phenomenon that seems to be "cheating" the classical laws of physics.
Scientists have long wondered how space chemistry occurs at such cold temperatures. That’s because when molecules come together, they need a little energy to break and form new bonds. But much of outer space is cold, lacking the energy to fuel these chemical reactions and overcome this energy barrier, study coauthor Dwayne Heard, a physical chemist at the University of Leeds in England, said in an interview.
"At these low temperatures, there's just simply not enough energy to get over the top of the barrier," Heard said.
And yet, such reactions must be taking place: Researchers have found a complex molecule called methoxy, one of the products of a reaction involving methanol. Methanol, a type of alcohol found in fuel and antifreeze, has a reputation for giving bootleg liquor its poisonous edge.
To find out how such chemical reactions were happening in cold, dark space, Heard and his colleagues created the same sort of environment in a lab -- bringing the thermostat down to around the same temperature seen in some interstellar gas clouds.
They found that at a freezing minus-346 degrees Fahrenheit, the reactions in the gas were actually happening faster in the cold, not slower – about 50 times faster than at room temperature.
"We were pretty surprised," Heard said.
How could this be? The scientists believe it's possible to shortcut the barrier to chemical reactions -- and the laws of classical physics -- with a phenomenon called quantum tunneling.
This little cheat code is made possible by the uncertainty principle in quantum physics. Think of an atom's position as a set of probabilities. Given that it can be very difficult to know a particle's exact position in front of a barrier, there's a low -- very low, but very real -- probability that the particle is actually on the other side of the barrier.
Obviously, objects -- your coffee, the car that rear-ended you this morning -- don't wink out of one place and reappear in another. But quantum physics works on tiny scales -- say, at the scale where atoms are whacking into one another, as they would be in these interstellar clouds of gas and dust.
It seems that the deep freeze, ironically, may actually be aiding the reactions in space, rather than impeding them. The cold slows down the molecules, which stay near each other for longer rather than quickly bouncing off of one another. Slowing them down widens the window of opportunity for quantum tunneling by a thousand times or even more, Heard said.
"We're talking about nanoseconds or something," Heard said, "but that is still a long time scale compared to a normal collision."