Weber bar

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title: "Weber bar" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["gravitational-wave-telescopes", "astronomy-in-the-united-states"] description: "Device used in gravitational wave observatories" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Weber_bar" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Device used in gravitational wave observatories ::

A Weber bar is a type of resonant mass gravitational wave detector designed to detect gravitational waves, devised and constructed by physicist Joseph Weber at the University of Maryland. Multiple of these devices were made, both of consisting of aluminium cylinders and stated to be 1.5 (5ft) meters in length, 0.6m (2ft) and 0.2m (8") in diameter, antennae for detecting gravitational waves. There is a third with a 1220 hertz resonance without stated length parameters.{{ cite journal |last1=Weber |first1=Joesph |title=Gravitational-Wave-Detector Events |journal=Physical Review Letters |date=3 June 1968 |volume=20 |issue=32 |pages=1307-1308 |doi=10.1103/PhysRevLett.20.1307 |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.20.1307 | access-date= 13 July 2025}}

A resonant mass gravitational wave detector in the style of the Weber bar is on display at Glasgow University. ::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/05/Resonant-bar-glasgow.jpg" caption="The Detector used in the "Search for Short Bursts of Gravitational Radiation" at [[Glasgow University]]." alt="Weber Bar type detector that was active in [[Glasgow University]]"] ::

Mechanism

These massive aluminium cylinders vibrated at a resonance frequency of 1660 or 1220 hertz and were designed to be set in motion by gravitational waves predicted by Weber. Because gravitational waves were predicted to be very weak, the size of the bars and were designed to be large to compensate since these waves cause a percentage change in length. These tiny displacements are then read out by piezoelectric sensors which had to be very sensitive, capable of detecting a change in the cylinders' lengths by about 10−16 meters. |url = https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.17.1228 |doi=10.1103/physrevlett.22.1320 |access-date= 13 July 2025}}

These bars were situated in a vacuum chamber, hung on acoustic filters which appear to be made up of masses on springs, with further isolation via rubber pads situated between steel blocks.

History

Around 1968, Weber collected what he concluded to be "good evidence" However, his experiments were duplicated many times, always with a null result.

Such experiments conducted by Joseph Weber were very controversial, and his positive results with the apparatus, in particular his claim to have detected gravitational waves from SN1987A in 1987, were widely discredited. Criticisms of the study have focused on Weber's data analysis and his incomplete definitions of what strength vibration would signify a passing gravitational wave.

Weber's first "Gravitational Wave Antenna" was on display in the Smithsonian Institution as part of "Einstein: a Centenary Exhibit" from March 1979 to March 1980. A second is on display at the LIGO Hanford Observatory. ::figure[src="https://upload.wikimedia.org/wikipedia/commons/3/3a/Weber_Memorial_Garden.jpg" caption="University of Maryland]]." alt="Eight large aluminum bars organized in an arch around a sign that says "Weber Memorial Garden" with a picture of Weber working on the detectors. The Garden can be found at the University of Maryland."] ::

Weber Memorial Garden was dedicated 2019 at the University of Maryland, where Weber was a faculty member. The garden contains eight of the cores of Weber's bar detectors.

References

References

1. Lindley, David. (22 December 2005). "A Fleeting Detection of Gravitational Waves". Physics.
2. (27 March 1967). "Gravitational Radiation". Physical Review Letters.
3. (May 1971). "The Detection of Gravitational Waves". Scientific American.
4. Einstein: A Centenary Exhibition. Edited by the National Museum of History and Technology. Washington, D.C.: Smithsonian Institution Press, 1979.
5. "Resonant Bar Detector Dedicated at Hanford". The LIGO web newsletter.
6. "Weber Garden Dedication Held March 12 - UMD Physics".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::