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[19.03] Where is the Planck time?

R. Lieu, H. Hillman (Physics Dept., Univ. Alabama at Huntsville)

It is widely believed that the Universe was created in a violent (kT ~h/t_P \approx 10²⁹ eV) explosion lasting t_P \approx 5.4 \times 10^-44 s, where t_P = (\hbar G/c⁵)^\frac{1}{2}, the Planck time, is an interval during which even time is a fuzzy concept. We present a method of directly testing whether time has its usual (i.e. classical) meaning on scales of \leq t_P. If indeed time and space cannot be known more precisely than t_P and c t_P, the same must apply to the period and wavelength of light, so that even the most monochromatic plane wave must in reality be a superposition of waves with independently varying \omega and k, each having a different phase velcocity \omega/k. For the entire accessible range of the electromagnetic spectrum this effect is extremely small, but can cumulatively lead to a complete loss of phase information if the emitted radiation propagated a sufficiently large distance. Since, at optical frequencies, the phase coherence of light from a distant point source is a necessary condition for the presence of diffraction patterns when the source is viewed through a telescope, such observations offer by far the most sensitive and uncontroversial test. We show that the HST detection of Airy rings from the active galaxy PKS1413+135, located at a distance of 1.2 Gpc, secures the exclusion of all first order Planck scale space-time fluctuations. This result may be used to deduce that the speed of light in vacuo is exact to a few parts in 10³².

If you would like more information about this abstract, please follow the link to http://arXiv.org/abs/astro-ph/0301184. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: lieur@cspar.uah.edu

Bulletin of the American Astronomical Society, 35#2
© 2003. The American Astronomical Soceity.