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RE: Fundamental Constant Mu
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A new research has determined that the laws of nature are the same in the distant Universe as they are here on Earth.
The research was conducted by an international team of astronomers, including Christian Henkel from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn.
It shows that one of the most important numbers in physics theory, the proton-electron mass ratio, is almost exactly the same in a galaxy 6 billion light years away as it is in Earths laboratories - approximately 1836.15.

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Fundamental constants
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The fundamental constants such as gravity and time are changing, according to 14th Astronomer Royal, Sir Arnold Wolfendale, who spoke at the Aline Wilmot Skaggs Biology Building Auditorium last week.
Citing such sources as physicist Paul Dirac, Wolfendale said there are striking similarities to the ratios of scientific constants and how big the universe is. In an example, Wolfendale showed that the decay length of a neutron is equal to the size of the universe. Why this matters to the public, according to Wolfendale, is that if the universe is expanding, scientific constants, such as time and gravity, might also be changing.

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Title: Variation of fundamental constants
Authors: V.V. Flambaum

We present a review of recent works devoted to the variation of the fine structure constant alpha, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra, Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a "nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude!
Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feschbach resonance.

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Molecular Hydrogen in Distant Galaxy
Credit ESO


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With ESO's VLT, Astronomers Find Molecular Hydrogen at Edge of Universe

Using a quasar located 12.3 billion light-years away as a beacon, a team of astronomers detected the presence of molecular hydrogen in the farthest system ever, an otherwise invisible galaxy that we observe when the Universe was less than 1.5 billion years old, that is, about 10% of its present age. The astronomers find that there is about one hydrogen molecule for 250 hydrogen atoms. A similar set of observations for two other quasars, together with the most precise laboratory measurements, allows scientists to infer that the ratio of the proton to electron masses may have changed with time. If confirmed, this would have important consequences on our understanding of physics.

"Detecting molecular hydrogen and measuring its properties in the most remote parts of the Universe is important to understand the gas environment and determine the rate of star formation in the early Universe" - Cédric Ledoux, lead-author of the paper presenting the results.

Although molecular hydrogen is the most abundant molecule in the Universe, it is very difficult to detect directly. For the time being, the only way to detect it directly in the far Universe is to search for its telltale signatures in the spectra of quasars or gamma-ray burst afterglows. This requires high spectral resolution and large telescopes to reach the necessary precision.

A team of astronomers, comprised of Cédric Ledoux (ESO), Patrick Petitjean (IAP, Paris, France) and Raghunathan Srianand (IUCAA, Pune, India), is conducting a survey for molecular hydrogen at high redshift using the Ultraviolet and Visible Echelle Spectrograph (UVES) at ESO's Very Large Telescope. Out of the 75 systems observed up to now, 14 have firm detection of molecular hydrogen. Among these, one is found having a redshift of 4.224.

While using the 12.3 billion light-years distant quasar PSS J 1443+2724 as a beacon, the astronomers detected several features belonging to an unseen galaxy having a redshift of 4.224. In particular, many lines from molecular hydrogen were found, breaking the record for the detection of this element in the farthest object in the Universe. This also implies that the gas in this galaxy must be rather cold, about -90 to -180 degrees Celsius.
In addition, several lines from 'metals' are also seen, allowing the researchers to deduce the amount of various chemical elements.

"From the abundance of Nitrogen observed, we argue that it had to be produced in the late stage of the life of 4 to 8 solar mass stars. Thus, star-formation activity must have formed at least 200 to 500 million years before we are observing the galaxy, that is, when the Universe was about one billion years old" - Patrick Petitjean.

If the galaxy went through a phase of intense star-formation activity, it is now, at the time of the observations, in a rather quiescent state.

"These observations demonstrate the possibility to perform these studies at the highest redshift with ESO's VLT. In particular, the possibility to observe the interstellar medium of distant galaxies revealed by using gamma-ray bursts as beacons will boost this field in the near future" - Raghunathan Srianand.

A similar set of accurate measurements of molecular hydrogen lines was made by the astronomers with UVES on the VLT towards two others quasars, Q 0405-443 and Q 0347-383.

This set of data allowed the scientists to compare the ratio of the mass of a proton to that of an electron in molecular hydrogen as it is now and how it was about 12 billion years ago. To this aim, they performed extremely accurate measurements of spectral lines of hydrogen molecules in the laboratory and compared the results with the same lines observed in the spectra of these quasars.
These measurements show that the mass ratio of the proton and the electron may have changed, becoming 0.002% smaller in the past twelve billion years. Albeit such a change may look tiny, it would have important consequences on our understanding of physics. The scientists stress however that their result is just an 'indication', not yet a 'proof' and that it should be confirmed by further measurements, both astronomical and in the laboratory.

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An experiment suggests that a fundamental constant of nature, called mu, the mass ratio of two fundamental subatomic particles has decreased over the last 12 billion years.

The startling finding comes from a team of scientists from the Free University in Amsterdam in the Netherlands and the European Southern Observatory in Chile, who have calculated exactly how much heavier a proton is than an electron. For most purposes, it is about 1,836 times heavier. But the researchers claim that this value has changed over time.
The constant governs the strong nuclear force, which holds protons and neutrons together in atomic nuclei, and is also responsible for binding the quarks – the building blocks which make up protons – neutrons and most other fundamental particles.

The researchers admit that they are only about 99.7% sure of their result, which physicists reckon is a little better than 'evidence for' but not nearly an 'observation of' the effect. If confirmed, however, the discovery could rewrite our understanding of the forces that make our Universe tick.

This is not the first time physicists have suspected physical constants of inconstancy.
In 1937, the physicist Paul Dirac famously suggested that the strength of gravity could change over time. And arguments about the fine-structure constant, alpha (α), have raged for years. The fine-structure constant measures the strength of the electromagnetic force that keeps electrons in place inside atoms and molecules.
Some physicists have argued that the equations describing our Universe allow for variance in the relative masses of a proton and electron. In fact, they have said, this value could theoretically vary more than alpha does, and so might be easier to pin down.

To look for such variation, Wim Ubachs, a physicist from the Free University in Amsterdam, the Netherlands, and his colleagues studied how a cool gas of hydrogen molecules in their lab absorbed ultraviolet laser light. The exact frequencies of light that are absorbed by each hydrogen molecule (H2), which is made of two protons and two electrons, depend on the relative masses of these constituent particles.
Then they compared this result with observations of two clouds of hydrogen molecules about 12 billion light years away, which are illuminated from behind by distant quasars. Although the light changes frequency on its long journey through space, researchers at the European Southern Observatory in Chile were able to unpick what the original frequencies absorbed by the hydrogen were.
The spectrum depends on the relative masses of protons and electrons in the molecule.

We concluded that the proton-electron mass ratio may have decreased by 0.002% in the past 12 billion years” - Wim Ubachs, team member .

Ubachs' comparison suggests that over this vast timescale, which is most of the lifetime of the Universe, the proton-to-electron mass ratio has decreased by 0.002%. The scientists report their research in Physical Review Letters.
The researchers laser measurements are hundreds of times more accurate than previous laboratory data. This improves their detection of the mass ratio effect by a factor of two to three.
Any change in mu, would support theories that posit extra dimensions. As these dimensions evolve, in a manner similar to our expanding 3D universe, the so-called constants would vary over both space and time. Or it may be that we still do not fully understand the proton: it may itself evolve through the universe’s lifetime, leading to the observed variation.

So what could be causing the ratio to change? It is unlikely that protons are losing weight. Instead, some theories suggest that extra dimensions occupied by the particle might be changing shape.

Or perhaps it's a consequence of the speed of light slowing down, or general relativity behaving in odd ways.
The observations could be improved or confirmed by looking at hydrogen clouds in the lab over a time period of, say, five years, but with a billion times greater precision. This would remove the difficulty of working out the precise wavelength of very dim light after it has passed through billions of light years of space.
But it could also remove the effect altogether.

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