The assumption of Newton's emission theory of light that the speed of light (as measured by the observer) varies with the speed of the emitter, c'=c+v, explains the Michelson-Morley experiment "without recourse to contracting lengths". The assumption of both the ether theory and special relativity that the speed of light is independent of the speed of the emitter, c'=c, is unable to explain the Michelson-Morley experiment "without recourse to contracting lengths":

http://books.google.com/books?id=JokgnS1JtmMC
"Relativity and Its Roots" By Banesh Hoffmann, p.92: "Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether."

Any explanation that depends crucially on "contracting lengths" is invalid because "contracting lengths" are absurd - they imply that arbitrarily long objects can be trapped inside arbitrarily short containers, both with and without compression:

http://math.ucr.edu/home/baez/physic...barn_pole.html
"These are the props. You own a barn, 40m long, with automatic doors at either end, that can be opened and closed simultaneously by a switch. You also have a pole, 80m long, which of course won't fit in the barn. (...) If it does not explode under the strain and it is sufficiently elastic it will come to rest and start to spring back to its natural shape but since it is too big for the barn the other end is now going to crash into the back door and the rod will be trapped IN A COMPRESSED STATE inside the barn."

http://www.quebecscience.qc.ca/Revolutions
Stéphane Durand: "Ainsi, une fusée de 100 m passant à toute vitesse dans un tunnel de 60 m pourrait être entièrement contenue dans ce tunnel pendant une fraction de seconde, durant laquelle il serait possible de fermer des portes aux deux bouts! La fusée est donc réellement plus courte. Pourtant, il n'y a PAS DE COMPRESSION matérielle ou physique de l'engin."

http://alcor.concordia.ca/~scol/semi...ts/Durand.html
Stéphane Durand: "La contraction une longueur est un phénomène à la fois réel mais sans déformation structurelle. C'est un phénomène réel (et non pas une illusion) car, par exemple, une perche dont la longueur au repos est plus grande que la longueur au repos d'une grange peut réellement être contenue dans cette dernière si elle se déplace assez rapidement. Par contre, il ne peut y avoir de contraction structurelle de la perche, i.e de déformation matérielle de l'objet, car la contraction de sa longueur aurait aussi lieu si c'était plutôt l'observateur qui se mettait en mouvement sans changer l'état de mouvement de la perche. Autrement dit, sans changer l'état de la perche, en se mettant soi-même en mouvement, on change sa longueur: ce n'est donc clairement pas une contraction matérielle (l'état de la perche est le même dans les deux cas). De plus, si deux observateurs se mettent en mouvement à des vitesses différentes par rapport à la perche, ces deux observateurs vont mesurer une longueur différente de la même perche. Une situation inexplicable en termes de contraction matérielle de la perche."

http://www.parabola.unsw.edu.au/vol3...ol35_no1_2.pdf
"Suppose you want to fit a 20m pole into a 10m barn. (...) Hence in both frames of reference, the pole fits inside the barn (and will presumably shatter when the doors are closed)."

Pentcho Valev