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The '''Hammar experiment''' was an experiment designed and conducted by [[Gustaf Wilhelm Hammar]] (1935) to test the [[aether drag hypothesis]]. Its negative result refuted some specific aether drag models, and confirmed [[special relativity]]. | |||
==Overview== | |||
Experiments such as the [[Michelson–Morley experiment]] of 1887 (and later other experiments such as the [[Trouton-Noble experiment]] in 1903 or the [[Trouton-Rankine experiment]] in 1908), presented evidence against the theory of a medium for light propagation known as the [[Luminiferous aether]]; a theory that had been an established part of science for nearly one hundred years at the time. These results cast doubts on what was then a very central assumption of modern science, and later led to the development of [[special relativity]]. In an attempt to explain the results of the Michelson-Morley experiment in the context of the assumed medium, aether, many new hypotheses were examined. One of the proposals was that instead of passing through a static and unmoving aether, massive objects at the Earth's surface may drag some of the aether along with them, making it impossible to detect a "wind". [[Oliver Lodge]] (1893-1897) was one of the first to perform a test of this theory by using rotating and massive lead blocks in an experiment that attempted to cause an asymmetrical aether wind. His tests yielded no appreciable results differing from previous tests for the aether wind.<ref>{{Cite journal|author=Lodge, Oliver J.|title=Aberration Problems|journal=[[Philosophical Transactions of the Royal Society A]]|volume=184|year=1893|pages=727–804|doi=10.1098/rsta.1893.0015|url=http://gallica.bnf.fr/ark:/12148/bpt6k559898/f781|bibcode = 1893RSPTA.184..727L }}</ref><ref>{{Cite journal|author=Lodge, Oliver J.|title=[[s:en:Experiments on the Absence of Mechanical Connexion between Ether and Matter|Experiments on the Absence of Mechanical Connexion between Ether and Matter]]|journal=[[Philosophical Transactions of the Royal Society A]]|volume=189|year=1897|pages=149–166|bibcode = 1897RSPTA.189..149L |doi = 10.1098/rsta.1897.0006 }}</ref> | |||
In the 1920s, [[Dayton Miller]] conducted repetitions of the Michelson–Morley experiments, which allegedly gave a positive result. However, several experiments conducted afterwards by others gave negative results. Miller claimed that this is due to entrainment of the aether, because the other experiments used heavily enclosed equipment. To test Miller's assertion, Hammar conducted the following experiment using a [[common path interferometer]] in 1935.<ref name=ham>{{cite journal | |||
| author= G. W. Hammar | |||
| year= 1935 | |||
| title= The Velocity of Light Within a Massive Enclosure | |||
| journal= [[Physical Review]] | |||
| volume= 48 | |||
| issue= 5 | |||
| pages= 462–463 | |||
| doi= 10.1103/PhysRev.48.462.2 | |||
|bibcode = 1935PhRv...48..462H }}</ref><ref name=rob>{{cite book | |||
| author= H. P. Robertson and Thomas W. Noonan | |||
| year= 1968 | |||
| title= Relativity and Cosmology | |||
| contribution=Hammar's experiment | |||
| publisher= Saunders | |||
| location= Philadelphia | |||
| pages= 36–38}}</ref> | |||
==The experiment== | |||
[[File:Hammar experiment.svg|center]] | |||
Using a half-silvered mirror A, he divided a ray of white light into two half-rays. One half-ray was sent in the transverse direction into a heavy walled steel pipe terminated with lead plugs. In this pipe, the ray was reflected by mirror D and sent into the longitudinal direction to another mirror C at the other end of the pipe. There it was reflected and sent in the transverse direction to a mirror B outside of the pipe. From B it traveled back to A in the longitudinal direction. The other half-ray traversed the same path in the opposite direction. | |||
The topology of the light path was that of a [[Common path interferometer#Sagnac|Sagnac]] interferometer with an odd number of reflections. Sagnac interfometers offer excellent contrast and fringe stability,<ref name=Optics471ASagnac>{{cite web |title=The Sagnac Interferometer |url=http://www.optics.arizona.edu/opti471a/Sagnac/The%20Sagnac%20Interferometer.pdf |publisher=University of Arizona College of Optical Sciences |accessdate=30 March 2012}}{{dead link|date=October 2013}}</ref> and the configuration with an odd number of reflections is only slightly less stable than the configuration with an even number of reflections. (With an odd number of reflections, the oppositely traveling beams are laterally inverted with respect to each other over most of the light path, so that the topology deviates slightly from strict common path.<ref name=Hariharan2007>{{cite book |last=Hariharan |first=P |title=Basics of Interferometry, 2nd edition |year=2007 |publisher=Elsevier |isbn=0-12-373589-0 |page=19}}</ref>) The relative immunity of his apparatus to vibration, mechanical stress and temperature effects, allowed Hammar to detect fringe displacements as little as 1/10 of a fringe, despite using the interferometer outdoors in an open environment with no temperature control. | |||
Similar to Lodge's experiment, Hammar's apparatus should have caused an asymmetry in any proposed aether wind. Hammar's expectation of the results was that: With the apparatus aligned perpendicular to the aether wind, both long arms would be equally affected by aether [[entrainment (hydrodynamics)|entrainment]]. With the apparatus aligned parallel to the aether wind, one arm would be more affected by aether entrainment than the other. The following expected propagation times for the counter-propagating rays were given by [[Howard Percy Robertson|Robertson]]/Noonan:<ref name=rob /> | |||
:<math>t_{1}=\frac{AB}{c+v}+\frac{BC+DA}{\sqrt{c^{2}-v^{2}}}+\frac{CD}{c-v+\Delta v} </math> | |||
:<math>t_{2}=\frac{AB}{c-v}+\frac{BC+DA}{\sqrt{c^{2}-v^{2}}}+\frac{CD}{c+v-\Delta v}</math> | |||
where <math>\Delta v</math> is the velocity of the entrained aether. This gives an expected time difference: | |||
:<math>\Delta t\simeq\frac{2l\Delta v}{c^{2}} </math> | |||
On September 1, 1934, Hammar set up the apparatus on top of a high hill two miles south of Moscow, Idaho, and made many observations with the apparatus turned in all directions of the azimuth during the daylight hours of September 1, 2, and 3. He saw no shift of the interference fringes, corresponding to an upper limit of <math>\Delta v<0.074</math> km/s.<ref name=ham/> These results are considered a proof against the aether drag hypothesis as it was proposed by Miller.<ref name=rob/> | |||
==Consequences for Aether drag hypothesis== | |||
{{Main|Aether drag hypothesis}} | |||
Because differing ideas of "aether drag" existed, the interpretation of all aether drag experiments can be done in the context of each version of the hypothesis. | |||
# None or partial entrainment by any object with mass. This was discussed by scientists such as [[Augustin-Jean Fresnel]] and [[François Arago]]. It was refuted by the [[Michelson–Morley experiment]]. | |||
# Complete entrainment within or in the vicinity of ''all'' masses. It was refuted by the [[Aberration of light]], [[Sagnac effect]], [[Oliver Lodge]]'s experiments, and Hammar's experiment. | |||
# Complete entrainment within or in the vicinity of only ''very large'' masses such as Earth. It was refuted by the [[Aberration of light]], [[Michelson–Gale–Pearson experiment]]. | |||
==References== | |||
<references /> | |||
{{Tests of special relativity}} | |||
{{DEFAULTSORT:Hammar Experiment}} | |||
[[Category:Physics experiments]] | |||
[[Category:Aether theories]] | |||
Latest revision as of 17:12, 6 September 2013
The Hammar experiment was an experiment designed and conducted by Gustaf Wilhelm Hammar (1935) to test the aether drag hypothesis. Its negative result refuted some specific aether drag models, and confirmed special relativity.
Overview
Experiments such as the Michelson–Morley experiment of 1887 (and later other experiments such as the Trouton-Noble experiment in 1903 or the Trouton-Rankine experiment in 1908), presented evidence against the theory of a medium for light propagation known as the Luminiferous aether; a theory that had been an established part of science for nearly one hundred years at the time. These results cast doubts on what was then a very central assumption of modern science, and later led to the development of special relativity. In an attempt to explain the results of the Michelson-Morley experiment in the context of the assumed medium, aether, many new hypotheses were examined. One of the proposals was that instead of passing through a static and unmoving aether, massive objects at the Earth's surface may drag some of the aether along with them, making it impossible to detect a "wind". Oliver Lodge (1893-1897) was one of the first to perform a test of this theory by using rotating and massive lead blocks in an experiment that attempted to cause an asymmetrical aether wind. His tests yielded no appreciable results differing from previous tests for the aether wind.[1][2]
In the 1920s, Dayton Miller conducted repetitions of the Michelson–Morley experiments, which allegedly gave a positive result. However, several experiments conducted afterwards by others gave negative results. Miller claimed that this is due to entrainment of the aether, because the other experiments used heavily enclosed equipment. To test Miller's assertion, Hammar conducted the following experiment using a common path interferometer in 1935.[3][4]
The experiment
Using a half-silvered mirror A, he divided a ray of white light into two half-rays. One half-ray was sent in the transverse direction into a heavy walled steel pipe terminated with lead plugs. In this pipe, the ray was reflected by mirror D and sent into the longitudinal direction to another mirror C at the other end of the pipe. There it was reflected and sent in the transverse direction to a mirror B outside of the pipe. From B it traveled back to A in the longitudinal direction. The other half-ray traversed the same path in the opposite direction.
The topology of the light path was that of a Sagnac interferometer with an odd number of reflections. Sagnac interfometers offer excellent contrast and fringe stability,[5] and the configuration with an odd number of reflections is only slightly less stable than the configuration with an even number of reflections. (With an odd number of reflections, the oppositely traveling beams are laterally inverted with respect to each other over most of the light path, so that the topology deviates slightly from strict common path.[6]) The relative immunity of his apparatus to vibration, mechanical stress and temperature effects, allowed Hammar to detect fringe displacements as little as 1/10 of a fringe, despite using the interferometer outdoors in an open environment with no temperature control.
Similar to Lodge's experiment, Hammar's apparatus should have caused an asymmetry in any proposed aether wind. Hammar's expectation of the results was that: With the apparatus aligned perpendicular to the aether wind, both long arms would be equally affected by aether entrainment. With the apparatus aligned parallel to the aether wind, one arm would be more affected by aether entrainment than the other. The following expected propagation times for the counter-propagating rays were given by Robertson/Noonan:[4]
where is the velocity of the entrained aether. This gives an expected time difference:
On September 1, 1934, Hammar set up the apparatus on top of a high hill two miles south of Moscow, Idaho, and made many observations with the apparatus turned in all directions of the azimuth during the daylight hours of September 1, 2, and 3. He saw no shift of the interference fringes, corresponding to an upper limit of km/s.[3] These results are considered a proof against the aether drag hypothesis as it was proposed by Miller.[4]
Consequences for Aether drag hypothesis
Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. Because differing ideas of "aether drag" existed, the interpretation of all aether drag experiments can be done in the context of each version of the hypothesis.
- None or partial entrainment by any object with mass. This was discussed by scientists such as Augustin-Jean Fresnel and François Arago. It was refuted by the Michelson–Morley experiment.
- Complete entrainment within or in the vicinity of all masses. It was refuted by the Aberration of light, Sagnac effect, Oliver Lodge's experiments, and Hammar's experiment.
- Complete entrainment within or in the vicinity of only very large masses such as Earth. It was refuted by the Aberration of light, Michelson–Gale–Pearson experiment.
References
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The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
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In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang - ↑ 3.0 3.1 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting
In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang - ↑ 4.0 4.1 4.2 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - ↑ Template:Cite webTemplate:Dead link
- ↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534