Physical constants

Many physics calculations rely on the assumption that the ‘physical constants’ e.g. light-speed, gravity, etc etc are, in fact, constant. Extremely accurate experimental procedures strongly suggest that they (mostly) are. But the experiments can only be carried out on a ‘local’ scale, and in a very short timeframe (cosmologically speaking). Thus the possibility exists that some constants may vary at extreme distances and/or timescales. If so, current explanations of many cosmological phenomena may have to be completely re-evaluated.

Further reading: The Variability of Fundamental Constants [archived] (by Dr Rupert Sheldrake )

In 2007, the MAGIC telescope array at La Palma, Canary Islands (Spain) found that high energy photons arriving from distant gamma ray burstsplugin-autotooltip__plain plugin-autotooltip_bigGamma-ray bursts

Gamma-Ray Bursts (GRBs) were first discovered by satellites originally intended to scan for nuclear weapon detonations.They range from bursts of ten milliseconds to several hours, and also have differing energy levels. They are generally unexplained. arrived at different times - the delay (max. of several minutes) being determined by the photon's wavelength (i.e. energy).

See 'Gamma Ray Delay May Be Sign of 'New Physics'' (UC Davis).

As the physical constants have been measured with increasing accuracy, many scientists and philosophers have asked why the constants have the values which they do. Although no-one has been able to answer the question, it's been pointed out that if (many of) the constants had even slightly differing values, then the Universe could not exist in its present form.

This is the so-called Anthropic Principle - which (broadly) states that constants must have the values which they do, or we would not be here to analyse them.

Further details : University of Oregon, US

Also see : The Gravitational constantplugin-autotooltip__plain plugin-autotooltip_bigThe Gravitational constant

The gravitational attraction between two objects is dependent on the mass of the objects, the distance between them, and the gravitational constant (G).

The masses and distance can vary, but the constant, as the name implies, is always a fixed number. and The Fine Structure Constantplugin-autotooltip__plain plugin-autotooltip_bigThe Fine Structure Constant

The Fine Structure Constant, identified by the Greek letter α is a fundamental number used in quantum physics calculations. The current estimate is that it's around 0.00729735256 - or roughly 1/137.

It has been called the "coupling constant" - or the measure of the strength of the electromagnetic force which governs how electrically-charged elementary particles (e.g., electron, muon) and light (photons) interact. It was introduced in 1916 by physicist Arnold …

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