When it comes to testing Scientific hypotheses, some disciplines have it easier than others. In a biology lab, for example, you might have living cells to poke and push, or in a chemistry lab, you might be able to clearly see the reactions of chemical compounds. But for physicists who study invisible phenomena like gravity And over time, proving scientific predictions can become a little more difficult.
In particular, physicists have a history of – literally – going to great lengths to test Albert Einstein’s theories about General relativity Through the incoherent chimes of highly accurate atomic clocks. atomic clock They are taken to the top of tall buildings, fly on planes, and even on spaceships in search of answers. Now, researchers from JILA Research Institute Give the most accurate measurement to date of this question on a 1 millimeter scale on a piece of paper published Wednesday in the magazine temper tantrums.
Toby Bothwell He is the first author on the paper and a graduate student at the University of Colorado, Boulder. Say backwards That this new measurement is made on the back of decades of current research.
In 2010 researchers at NIST [National Institute of Standards & Technology] Compare two aluminum clocks separated vertically by 30 cm, which is the smallest distance before this result,” said Bothwell. “We created a new experimental device using the latest results from decades of progress… a scale of about 200 microns, not much larger than a human hair – and a factor of 1,000 times smaller than the previous best results. “
Here is the background – From a human point of view, time is the only currency we cannot manipulate. We age at the same rate every day and time moves at the same rate for all living things – as the saying goes, we all have the same hours in a day as Beyoncé.
Except, according to Einstein’s 1915 prediction, this might actually be fundamentally wrong.
According to his general theory of relativity, Einstein postulated that gravity could actually affect the flow of time and that objects farther away from Earth’s gravity (for example, atomic clocks on airplanes) should “travel” through time travel in a short period of time. time but very different levels. The idea that time experience is not static is called “time dilation”.
For scientists like Bothwell, this time dilation effect can be measured using highly accurate atomic clocks and can help not only confirm Einstein’s theory but also reveal more about the relationship between quantum mechanics and gravity.
–
–
–
why it matters – Although it is a force that we experience every day, gravity is actually one of the fundamental forces that is less compatible with other forces in our universe, including electromagnetism and nuclear forces. It is well known that gravity and quantum mechanics do not mix and represent a huge gap between our understanding of the entire human world and the quantum-controlled world of particles.
john you He is a co-author of the paper and principal investigator for the JILA Research Group. He said future atomic experiments at this scale or smaller could be an important step towards understanding how gravity works at small scales.
“In the microscopic quantum world, atoms are sometimes represented by quantum waves [and] quantum wavelength[s] It can extend to several microns,” Ye . said backwards. “We wanted our clocks to gain sensitivity so that on this wavelength scale it could tell us that time evolved differently, all because of Mother Earth’s very microscopic body.”
In addition, Bothwell says that more accurate measurements of this expansion also have the practical purpose of correcting accumulated GPS errors caused by deviated clocks and even one day serving as an early warning system for volcanic eruptions by detecting small changes in Earth’s elevation. Crust.
–
What are they doing – To perform these measurements, the team looked at 100,000 ultra-cold strontium atoms in their lab trapped inside an optical lattice, which Yi described in the experimental video as a stack of pancakes.
The team then sliced up these stacks of “cake” atoms, separating them by 1 millimeter. They reported that the atoms were able to maintain their combined energy state for 37 seconds before the time-widening effect persisted and pushed the clock slightly out of alignment. With more than 90 hours of data, the team was able to measure this slight decoherence with 50 times greater accuracy than previous atomic clock comparisons.
Then, how – Going forward, Bothwell said the team is excited to work on shortening the distance between retinal clocks even further. Through this work, he hopes to get closer to understanding the nature of spacetime itself.
“We still have a long way to go before such clocks are sensitive to the curvature of space-time and raise questions about the relationship between gravity and quantum mechanics,” said Bothwell. “[But] With the improved laser, we can measure time dilation to below the 100 micron scale, and continue to drive sensitivity to the curvature of space-time.”
Summary – Einstein’s theory of general relativity states that clocks with different gravitational potentials tick at different rates relative to laboratory coordinates – an effect known as gravitational redshift. As basic probes of space and time, atomic clocks have long worked to test these predictions at distances ranging from 30 centimeters to thousands of kilometers. Ultimately, clocks will allow the study of the unification of general relativity and quantum mechanics once they become sensitive to wavefunctions to quantum objects oscillating in curved space-time. In the direction of this system, we measure a linear frequency gradient corresponding to the gravitational redshift in a single millimeter-scale ultra-cold strontium sample. Our results were made possible by increasing the uncertainty in the partial frequency measurements by more than 10 times, now reaching 7.6 × 10−21. This signals a new clock operating system that requires correction in the sample for gravitational perturbations.
–
