7/14/2023 0 Comments Time warp definitionYe’s clock could detect an even smaller discrepancy between the two halves of the clock of one second amassed over roughly 4 trillion years. With that sensitivity, scientists could detect a difference between two clocks ticking at a rate so slightly different that they’d disagree by just one second after about 300 billion years. Shimon Kolkowitz of the University of Wisconsin–Madison and colleagues measured the relative ticking rates of two of the clocks, separated by about six millimeters, to a precision of 8.9 millionths of a trillionth of a percent, which itself would have been a new record had it not been beat by Ye’s group. “It’s very exciting what they did, as well,” Safronova says. In a related study, also submitted September 24 to, another team of researchers loaded strontium atoms into specific portions of a lattice to create six clocks in one. That makes it a record for the most precise frequency comparison ever performed. What’s more, after taking data for about 90 hours, comparing the ticking of upper and lower sections of the clock, the scientists determined their technique could measure the relative ticking rates to a precision of 0.76 millionths of a trillionth of a percent. This atomic clock, located at JILA, is similar to the one used in the new research by Jun Ye and colleagues, and uses laser light to hold strontium atoms in a lattice. Atomic clocks (one shown in a composite image) keep time by measuring the frequency of light that initiates a jump between energy levels in atoms. After correcting for non-gravitational effects that could shift the frequency, the clock’s frequency changed by about a hundredth of a quadrillionth of a percent over a millimeter, just the amount expected according to general relativity. Mapping out how the frequency changed over those heights revealed a shift. Those atoms were arranged in a lattice, meaning that the atoms sat at a series of different heights as if standing on the rungs of a ladder. In the new study, physicist Jun Ye of JILA in Boulder, Colo., and colleagues used a clock made up of roughly 100,000 ultracold strontium atoms. Previously, scientists have measured this frequency shift, known as gravitational redshift, across a height difference of 33 centimeters ( SN: 9/23/10). For atoms farther from the ground, time runs faster, so a greater frequency of light will be needed to make the energy jump. That frequency - the rate of wiggling of the light’s waves - serves the same purpose as a clock’s regularly ticking second hand. Atoms exist at different energy levels, and a specific frequency of light makes them jump from one level to another. “I thought it would take much longer to get to this point.” The extreme precision of the atomic clock’s measurement suggests the potential to use the sensitive timepieces to test other fundamental concepts in physics.Īn inherent property of atoms allows scientists to use them as timepieces. “This is fantastic,” says theoretical physicist Marianna Safronova of the University of Delaware in Newark, who was not involved with the research. Time moved slightly faster at the top of that sample than at the bottom, researchers report September 24 at. Now an incredibly sensitive atomic clock has spotted that speedup across a millimeter-sized sample of atoms, revealing the effect over a smaller height difference than ever before. Theoretically, that should hold true even for very small differences in the heights of clocks. But even a distance that small can alter the flow of time.Īccording to Einstein’s theory of gravity, general relativity, clocks tick faster the farther they are from Earth or another massive object ( SN: 10/4/15).
0 Comments
Leave a Reply. |