Explore further More information: Is a tabletop search for Planck scale signals feasible, arXiv:1211.3816 [gr-qc] arxiv.org/abs/1211.3816AbstractQuantum gravity theory is untested experimentally. Could it be tested with tabletop experiments? While the common feeling is pessimistic, a detailed inquiry shows it possible to sidestep the onerous requirement of localization of a probe on Planck length scale. I suggest a tabletop experiment which, given state of the art ultrahigh vacuum and cryogenic technology, could already be sensitive enough to detect Planck scale signals. The experiment combines a single photon’s degree of freedom with one of a macroscopic probe to test Wheeler’s conception of “spacetime foam”, the assertion that on length scales of the order Planck’s, spacetime is no longer a smooth manifold. The scheme makes few assumptions beyond energy and momentum conservations, and is not based on a specific quantum gravity scheme. Set up of suspended blocks showing (dotted) the alternative paths for the photon. E is the single-photon emitter, D and D’ are the single-photon detectors. BS denotes the beamsplitter and M the mirror. DL is the fiber optics delay line, and EB are the electronics that trigger D and D’ through cable C. The optical elements to widen the beam before and focus it after each block are left out for clarity. In the real experiment the blocks would hang side by side. Credit: arXiv:1211.3816 [gr-qc] Citation: Physicist proposes simple experiment to detect foam-like structure of the universe (2012, November 23) retrieved 18 August 2019 from https://phys.org/news/2012-11-physicist-simple-foam-like-universe.html Journal information: arXiv (Phys.org)—Prominent physicist Jacob D. Bekenstein, of the Hebrew University of Jerusalem, has proposed a simple experiment in a paper he’s uploaded to the preprint server arXiv, that he says could be used to measure quantum foam. Instead of looking to ever faster particle accelerators, he proposes using an ordinary block of glass, a laser and a detector.