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Remove "fundamental", since this is used less for dimensionful constants. See this linked physical constant page for reasoning. |
m →Potential variation over time: wp:noted fix to an ordinary sentence. Tags: Mobile edit Mobile app edit Android app edit App section source |
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They proposed using this effect to measure the value of {{mvar|α}} during the epoch before the formation of the first stars. In principle, this technique provides enough information to measure a variation of 1 part in {{val|e=9}} (4 orders of magnitude better than the current quasar constraints). However, the constraint which can be placed on {{mvar|α}} is strongly dependent upon effective integration time, going as {{frac|{{sqrt|{{mvar|t}} }} }}. The European [[Low-Frequency Array (LOFAR)|LOFAR]] [[radio telescope]] would only be able to constrain {{sfrac| {{math|Δ}}{{mvar|α}} | {{mvar|α}} }} to about 0.3%.<ref name=Khatri/> The collecting area required to constrain {{sfrac| {{math|Δ}}{{mvar|α}} | {{mvar|α}} }} to the current level of quasar constraints is on the order of 100 square kilometers, which is economically impracticable at
=== Present rate of change ===
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|url=https://zenodo.org/record/1230892
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used the frequency ratio of {{chem2|Al+}} and {{chem2|Hg+}} in single-ion optical atomic clocks to place a very stringent constraint on the present-time temporal variation of {{mvar|α}}, namely {{sfrac| {{math|Δ}}{{mvar|α}} | {{mvar|α}} }} = {{val|-1.6|2.3|e=-17}} per year.
{{cite journal
|last1=Barrow |first1=John D.
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