Time Marches On...But How?
(From the May/June 2003 issue of StarDate magazine)
Recent findings may challenge a popular theory of modern physics: Time (like light, and even gravity) breaks down into small but measurable pieces, called quanta. (The quantum, or particle, of light is the photon.) The existence of the quantum of time — or lack thereof — should have consequences for whether the Big Bang theory is correct, and whether relativity and quantum physics (the two theories that explain the universe on the largest and smallest scales, respectively) can ever be reconciled. Richard Lieu and Lloyd Hillman of The University of Alabama in Huntsville looked at Hubble Space Telescope images of galaxies at least four billion light-years from Earth. They searched for patterns in the images that should not be present if prevailing notions of the time quantum are correct. “I fully anticipated that the pattern wouldn’t show,” Lieu said. Instead, he and Hillman found the tell-tale interference pattern — a ring around the galaxies.
They used this to calculate that the speed of this light did not fluctuate by more than a few parts in many trillions (specifically, 10-32) in its four-billion-year voyage to Hubble’s detector. They say that this measurement is much more accurate than should be possible if time indeed is a quantum phenomenon.
The reasoning has to do with uncertainties. Scientists say that distances and times smaller than Planck scales (trillionths of a centimeter, and how long it takes light to travel that far, respectively) are “fuzzy.” That is, they can’t be measured. That means there are limits on how accurately scientists can measure the speed of light. So, Lieu says, there could be fluctuations in the speed of light at distances smaller than the Planck scale.
These tiny fluctuations would become apparent only in light that has traveled a great distance. After traveling so long, the faster parts of the light waves would be far enough ahead and the slower parts far enough behind that the light would be distorted (or blurred) enough for a telescope to measure it. But Lieu and Hillman didn’t find this distortion in the images. Lieu says this means that time is not a quantum function. — Rebecca Johnson
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