Retarded distances and relativistic length

It is stressed that relativistic electrodynamics uses solely retarded distances. Therefore the relativistic length introduced earlier and which expressed as a half-sum of two retarded distances is connected organically with electrodynamics. At the same time instantaneous distance is an alie element to it. Considerations are produced that based on analogy with electromagnetic and gluon field the behaviour of longitudinal sizes of fast must be described by elongation formula, arising from the concept of the relativistic length. 6 refs.; 1 fig