how gravity and lasers are helping us learn more about the universe
The best way to understand the fabric of space and time might just involve a fifth state of matter and falling for a really long time...
We’re all familiar with the four states of matter. Smooth, creamy, chunky, and crunchy. No, wait, that’s pastry. What I meant to say was solid, liquid, gas, and plasma. But there is a fifth state of matter that occurs in very exotic conditions called a Bose-Einstein Condensate. The best way to describe it is as atoms at rest, and it happens only when matter is within a hair of absolute zero. Whether it’s found in nature is still an open question because places like the Boomerang Nebula should theoretically be cold enough to create it at a literally electron-stopping -272.15 °C, but we can make it in a lab for short amounts of time by using lasers and rubidium atoms.
The recipe for making your own BEC cloud is actually not that complicated. Step one, trap a decent amount of rubidium atoms into a electrically charged trap. If you didn’t create any rubidium atoms for this exact experiment, store bought is fine, and feel free to substitute for any other matter. Step two is what’s important. Use carefully timed laser pulses to stop the atoms from moving by strategically hitting them to take away their inertia. Step three is to keep doing that until all the atoms in the trap come as close to a complete stop as possible. If you did it right, the temperature will be just about -273.15 °C, also known as absolute zero.
In this environment, the atoms will begin to behave as one because they’re all in the same quantum state. And this is an extremely useful phase of matter for scientists because anything colliding with them, or any motion affecting their configuration is vastly amplified. It could be used to detect gravitational waves, map interference signals from bizarre particles, and shed light on other subatomic phenomena. The only problem is that the condensate is short lived. Atoms in this low energy state will fall in the trap as gravity will continue to act on it and you have milliseconds to carry out your experiments.
Now, German researchers created a way to radically extend the amount of time they can keep matter chilled enough for their experiments by creating the EBC cloud in a rocket, launching it into space, and letting freefall keep the cloud from hitting the bottom of the trap. In a six minute flight on a sounding rocket, they managed to perform over 100 tests to determine the ability of the condensate to detect external interference and how gravity affects its configuration. The results were so encouraging, they’re planning to launch further flights using potassium atoms, and mulling how to get their setup into a long term orbit.
Such a setup could help us understand more about things like cosmic rays, test theories about the fabric of space-time, and better understand the disconnect between gravity and quantum mechanics, hopefully pointing us towards the much needed Grand Unified Theory. Just like with falling antimatter, the goal here is to understand more about the universe at every scale and apply that knowledge to current and future problems. Considering that we’re using particle accelerators to help treat cancers and bolster our ability to exchange information and crunch through oceans to data, knowing more about the outer limits of physics might give us even more of an edge in building the world of tomorrow.