Disturbance in the Force – A Spatially Varying Fine Structure Constant

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In order for astronomers to explore the outer reaches of our universe, they rely upon the assumption that the physical constants we observe in the lab on Earth are physically constant everywhere in the universe. This assumption seems to hold up extremely well. If the universe’s constants were grossly different, stars would fail to shine and galaxies would fail to coalesce. Yet as far we we look in our universe, the effects which rely on these physical constants being constant, still seem to happen. But new research has revealed that one of these constants, known as the fine structure constant, may vary ever so slightly in different portions of the universe.

Of all physical constants, the fine structure constant seems like an odd one to be probing with astronomy. It appears in many equations involving some of the smallest scales in the universe. In particular, it is used frequently in quantum physics and is part of the quantum derivation of the structure of the hydrogen atom. This quantum model determines the allowed energy levels of electrons in the atoms. Change this constant and the orbitals shift as well.

Since the allowed energy levels determine what wavelengths of light such an atom can emit, a careful analysis of the positioning of these spectral lines in distant galaxies would reveal variations in the constant that helped control them. Using the Very Large Telescope (VLT) and the Keck Observatory, a team from the University of New South Whales has analyzed the spectra of 300 galaxies and found the subtle changes that should exist if this constant was less than constant.

Since the two sets of telescopes used point in different directions (Keck in the Northern hemisphere and the VLT in the Southern), the researchers noticed that the variation seemed to have a preferred direction. As Julian King, one of the paper’s authors, explained, “Looking to the north with Keck we see, on average, a smaller alpha in distant galaxies, but when looking south with the VLT we see a larger alpha.”

However, “it varies by only a tiny amount — about one part in 100,000 — over most of the observable universe”. As such, although the result is very intriguing, it does not demolish our understanding of the universe or make hypotheses like that of a greatly variable speed of light plausible (an argument frequently tossed around by Creationists). But, “If our results are correct, clearly we shall need new physical theories to satisfactorily describe them.”

While this finding doesn’t challenge our knowledge of the observable universe, it may have implications for regions outside of the portion of the universe we can observe. Since our viewing distance is ultimately limited by how far we can look back, and that time is limited by when the universe became transparent, we cannot observe what the universe would be like beyond that visible horizon. The team speculates that beyond it, there may be even larger changes in this constant which would have large effects on physics in such portions. They conclude the results may, “suggest a violation of the Einstein Equivalence Principle, and could infer a very large or infinite universe, within which our `local’ Hubble volume represents a tiny fraction, with correspondingly small variations in the physical constants.”

This would mean that, outside of our portion of the universe, the physical laws may not be suitable for life making our little corner of the universe a sort of oasis. This could help solve the supposed “fine-tuning” problem without relying on explanations such as multiple universes.

Want some other articles on this subject? Here’s an article about there might be 10 dimensions.