It is considered, that light puts pressure upon surfaces of subjects. Attempts of working out of flying machines for flight in Space under the influence of pressure of a sunlight therefore become. Thus there is a necessity of major expenditures on working out and designing of a solar sail. But may it be all for nothing?

  Dreams of a solar sail

Paradoxes of pressure of light. The phenomenon of the light pressure, known in modern physics, is inconsistent. So there are following paradoxes:

1) How can light to press on surface, if it is the harmonious oscillations of 2 directions, instead of a single half-period wave?

2) How can light to press, if the light oscillations on O.Frenel are the cross concerning the direction of the light propagation, so they are the longitudinal concerning the surface on which there is the pressure? *

J. Maxwell gives formula of pressure of the electromagnetic waves in "Treatise" without any deduction [26].     

Therefore physicists are forced to add to one "essence" of light (the undular) the second "essence" – the photon, in which the flux of light particles – the quantums strike the unilateral blows on a surface. However the presence of two substances at one object contradicts to bottoms of science. Hence the essence of light in the up-to-date physics is not erected until now.

The known indirect proofs of existence of the light pressure are not convincing also. It is P.N.Lebedev's experience [38]. The  resonators have been used in the proofs.  It is revealed the two-digit influence of waves on the resonator – both: the pushing away of the resonator from a wave, and the attraction (fig. 25, 26).

Fig. 25. Plan of the experience of P.N.Lebedev on detection of pressure of the electromagnetic waves.

B – the vibrator, Г – the generator, Р – the resonator.

 Fig. 26. Plan of the experience of P.N.Lebedev on detection of pressure of waves in fluid

on the solid surface.

B – the actuator of waves, Р – the resonator, Д – the drive, A – the lever gear.

Explanations are not present to it. There is no explanation to the anomaly – the disappearance of an attraction  of the acustic resonator at its removal from the radiant of the oscillations. However this anomaly undertakes as the bottom and is transferred on the electromagnetic oscillations with the referring to the unfounded statement of J. Маxwell.

Besides P.N. Lebedev created the very complicated devices for the proof of existence of light pressure. Therefore these  devicaes respond at a set of by-effects.  It means – the experiments were not pure. 

According to the essence of the electromagnetic waves the pressure of light can not arise**.  Accordingly the flight in Space it is physically impracticable on the basis of the existing concept of pressure of light. Flights between the proximate planets and outside of Solar system are possible further only at mastering by secrets of Gravitation. These secrets are uncovered in Unified Theory of Nature (Essence of Gravitation see and other). The bottoms of engineering possibilities of guidance of Gravity and flights in Space will be featured further (Antigravitational kettles see) . 

* The cross (superficial) oscillations of  fluid  can render the side pressure on the  hindrance on trajectory of the distribution of these transverse waves (for example, on a sea mooring).  But this side pressure is caused by the versatile motion of particles of the fluid – molecules (atoms) that not present in the light wave (according to the up-to-date representations about the light wave). This featured the side pressure is not necessary to immix with one more the pressure of the superficial waves. So at the inhibiting of the lower part of a sinusoidal superficial water wave (for example, on a shoal of water area) the undular motion is transmuted  into the mass motion. It is appears the flow in the upper part of the upseting wave. The flow acts essentially differently, than the undular fluctuation of water  level at the mooring wall.  

** As to the tail of a comet ([38] see above) it can provoked  not the pressure of sunlight, but the convective flow of gas from the warmed field of a comet in the cold. Furthermore, as the comet tail has the shape not the direct, but the incurvated in form of the peacock tail. This  confirms  Unified Theory of Nature, as indicates to the  motion of the arched jets of the solar mesovortex of ether about a comet and through it (Formation of stars see).