In Brief To connect classical physics and quantum physics, physicists used two rubidium atoms to see if the effects of gravity are affected by the atoms’ quantum spins.
Physicists have just found more compelling evidence implying that gravity, which determines how massive objects impact the fabric of spacetime, just doesn’t honor the laws of quantum physics, which governs the world of the very, very small.
To break this down, the biggest challenge in modern physics is finding some form of agreement between classical physics and quantum physics.
By using two rubidium atoms with opposite quantum spins, the scientists were hoping to find evidence that, at molecular sizes, the laws of quantum physics would somehow affect gravity and therefore form a connection between quantum physics and classical physics.
The experiment showed that gravity paid no heed to the atoms’ opposite quantum spins and gave them the same treatment as all other objects: The equivalence principle still prevailed.
The atoms fell at pretty much identical rates, meaning that even at quantum scales, the laws of classical physics for gravity still apply.
This is a problem in that there is still no way to connect the two aspects of physics to each other, making the attempt to arrive at a unified theory a vain one.