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A-Z of thought: Laws of physics

John Ling


The laws of physics reflect the nature of the environments. They may be said to note patterns and relationships between quantities such as distance and time. Laws seek to be true within the scope of their validity. Ohm's law seems a simple example. The relationship between voltage (V) and current (I) is described using the simple mathematical formula: V=IR (where R denotes electrical resistance).

This mathematical relationship is not, however, a law. Ohm's law is more precisely stated as: 'The voltage dropped across a metallic conductor is proportional to the current flowing through it at a constant temperature.'
Laws, like Ohm's law are empirically derived. They are based on observation and experiment. The mathematical relationship, in this case does not completely express the law, but laws may be described by mathematical relationships. Indeed the elegance and simplicity of some mathematical descriptions has led some to conjecture about the relationship between symmetry, patterns and the underlying structure of the physical world.

Laws are true wherever they are tested and hence do not have verifiable contradictory evidences. But this is not necessarily how laws are practically applied. An A-level physicist may be asked to demonstrate whether a resistor is Ohmic, independent of material chemistry; i.e. whether there is proportionality between the potential difference across the resistor and the current flowing through it. Another complication in working with laws is dealing with the nature of practical data. All experiments have uncertainties, due both to experimental design and to the precision of the instruments used. So assessment of compliance with empirically based laws may require a wider appreciation of experimental method.

What at first seems like a simple proposition can quickly raise the need for further refinement of direction. Problems about the correct association of a law to a particular situation are one of a number of issues to be addressed. To some readers these ideas may have a common resonance to other areas of life. It is not just the physicist who looks to the heart of the matter seeking for truth. Religious truth also may start with apparently simple statements of relationship. But the religious observer finds that deeper examination leads to a refinement of position without altering core aspects of the initial assessment. Is this coincidental or does it reveal that the search for truth, whether it be scientific or religious follows a similar pathway.

To a Christian physicist a solution might be apparent: the nature of truth reflects the nature of an underlying coherency.

John Ling