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The drag coefficient of Fresnel



The drag coefficient of Fresnel

When you are inter­ested in physics you must read “Unbe­liev­able”!

Bradley observed the stel­lar aber­ra­tion of the star y–Dra­co­nis in 1727. We demon­strated in the pre­vi­ous chap­ters that the con­clu­sion of sci­ence that there could not be dragged ether was pre­ma­ture. The pre­sump­tion of sci­ence that dragged ether could not exist had con­se­quences; the stel­lar aber­ra­tion observed occurs so there had to be an other explanation.

The light of a star in a tele­scope is bent to the focus point. Sci­ence assumed, to be able to explain stel­lar aber­ra­tion, that the light from the star kept mov­ing side­ways in the tele­scope. When the beams of light from the star hit the lens of the tele­scope right-​angled, then the image of the star would be side­ways of the cen­ter point because of the assumed con­tin­u­ing side­way move­ment of the light in the telescope.

The way sci­en­tists appar­ently assumed how stel­lar aber­ra­tion was achieved in the tele­scope is com­pa­ra­ble to a bul­let aimed at the heart. The vic­tim moves as quickly as pos­si­ble to the side to avoid the bul­let. The bul­let hits the heart away from where the shooter aimed because the vic­tim moved side­ways. Sci­ence argued there­fore that if the tele­scope is filled with water the observed aber­ra­tion would have to increase. Light trav­els slower in water than in a vac­uum or in air.

Because of the decrease of the speed of light in water one assumed that the light in the tele­scope, when filled with water, had more time to move side­ways and thus the aber­ra­tion would increase. The speed of light in water is c divided by the index n of water. The index of water is ca. n=1.33. The light of the star will stay longer in the tele­scope when it is filled with water. The light beam will have more time to move side­ways and there­fore sci­ence expected an increase of the stel­lar aber­ra­tion with a fac­tor 1.33.

To resume our anal­ogy with the vic­tim, the vic­tim is now shot with an arrow. The arrow is again aimed pre­cisely at the heart. The vic­tim runs side­ways as hard as he can and because the arrow takes longer to reach the heart, the spot where the heart is pen­e­trated must lie fur­ther side­ways. The vic­tim has more time to move side­ways before the arrow spears his heart.

In 1871 Sir Geofry Air con­ducted this exper­i­ment. He, how­ever, did not mea­sure any increase in aber­ra­tion. The aber­ra­tion of the star was the same with or with­out the tele­scope filled with water! This was not a really big sur­prise, because in 1818 Fres­nel had pos­tu­lated that there would be a “drag-​factor”.

Fres­nel came to this con­clu­sion after Arago had observed that the earth always seems to be “at rest” in the ether. But sci­ence had con­cluded ear­lier that the dragged ether did not exist. A drag fac­tor had to be intro­duced to “explain” the con­tra­dic­tion between “always at rest in ether” (Arago) and the pre­sumed “non-​existence” of the dragged ether.

Now sci­ence should have won­dered whether this was cor­rect. Appar­ently sci­ence was so fix­ated look­ing for absolute ether, that this obvi­ous sign was ignored. So to explain the lack of increase in stel­lar aber­ra­tion when the tele­scope was filled with water, a drag fac­tor had to be introduced!

The above is a very short his­tor­i­cal overview of the attempts of sci­en­tists to explain stel­lar aber­ra­tion. Find­ing any logic in the above is dif­fi­cult. Weird con­cepts were pro­posed by sci­en­tists to explain the phe­nom­ena, because the only log­i­cal expla­na­tion was denied.

The drag fac­tor of Fres­nel is:

f is the drag fac­tor of Fres­nel and n the refrac­tive index.

In gen­eral one can state that in the 19th cen­tury physi­cists were strongly con­vinced there was absolute ether in which light moves in all direc­tions with the same speed c. The ether was assumed to be absolute because exper­i­ments indi­cated that what­ever the cir­cum­stances the speed of light was always c. The absolute ether was by then the pre­sumed medium exist­ing in vac­uum by means of which light prop­a­gates. The absolute ether is con­sid­ered to be at rest while all the stars and plan­ets move in com­par­i­son to the absolute ether. When the ether can­not be influ­enced by any­thing than this ether is absolute. Only if the earth is at rest in the absolute ether then light will travel with equal speed in all direc­tions. When the earth is mov­ing in the absolute ether, the speed of light can­not be the same in all direc­tions because the light moves in the ether in all direc­tions with c. When the Earth moves rel­a­tive to the ether on Earth the speed of light can­not be c in all direc­tions because the light moves in the absolute ether in all direc­tions with c; you can­not have both at the same time.

In exper­i­ments it was observed that the speed of light was always c in all direc­tions. The dragged ether was denied and there­fore the only pos­si­ble form of ether left was the absolute ether. Because the Earth in her path around the Sun can­not always be at rest with the absolute ether there must be a phys­i­cal process explain­ing why the Earth appears to be at rest with the absolute ether. The drag fac­tor of Fres­nel was a pos­si­ble explanation.

Next chap­ter: The exper­i­ment of Fizeau

When you are interested in physics you must read “Unbelievable“!

Bradley observed the stellar aberration of the star y-Draconis in 1727. We demonstrated in the previous chapters that the conclusion of science that there could not be dragged ether was premature. The presumption of science that dragged ether could not exist had consequences; the stellar aberration observed occurs so there had to be an other explanation.

The light of a star in a telescope is bent to the focus point. Science assumed, to be able to explain stellar aberration, that the light from the star kept moving sideways in the telescope. When the beams of light from the star hit the lens of the telescope right-angled, then the image of the star would be sideways of the center point because of the assumed continuing sideway movement of the light in the telescope.

The way scientists apparently assumed how stellar aberration was achieved in the telescope is comparable to a bullet aimed at the heart. The victim moves as quickly as possible to the side to avoid the bullet. The bullet hits the heart away from where the shooter aimed because the victim moved sideways. Science argued therefore that if the telescope is filled with water the observed aberration would have to increase. Light travels slower in water than in a vacuum or in air.

Because of the decrease of the speed of light in water one assumed that the light in the telescope, when filled with water, had more time to move sideways and thus the aberration would increase. The speed of light in water is c divided by the index of water. The index of water is ca. n=1.33. The light of the star will stay longer in the telescope when it is filled with water. The light beam will have more time to move sideways and therefore science expected an increase of the stellar aberration with a factor 1.33.

To resume our analogy with the victim, the victim is now shot with an arrow. The arrow is again aimed precisely at the heart. The victim runs sideways as hard as he can and because the arrow takes longer to reach the heart, the spot where the heart is penetrated must lie further sideways. The victim has more time to move sideways before the arrow spears his heart.

In 1871 Sir Geofry Air conducted this experiment. He, however, did not measure any increase in aberration. The aberration of the star was the same with or without the telescope filled with water! This was not a really big surprise, because in 1818 Fresnel had postulated that there would be a “drag-factor”.

Fresnel came to this conclusion after Arago had observed that the earth always seems to be “at rest” in the ether. But science had concluded earlier that the dragged ether did not exist. A drag factor had to be introduced to “explain” the contradiction between “always at rest in ether” (Arago) and the presumed “non-existence” of the dragged ether.

Now science should have wondered whether this was correct. Apparently science was so fixated looking for absolute ether, that this obvious sign was ignored. So to explain the lack of increase in stellar aberration when the telescope was filled with water, a drag factor had to be introduced!

The above is a very short historical overview of the attempts of scientists to explain stellar aberration. Finding any logic in the above is difficult. Weird concepts were proposed by scientists to explain the phenomena, because the only logical explanation was denied.

The drag factor of Fresnel is:

f  is the drag factor of Fresnel and n the refractive index.

In general one can state that in the 19th century physicists were strongly convinced there was absolute ether in which light moves in all directions with the same speed c. The ether was assumed to be absolute because experiments indicated that whatever the circumstances the speed of light was always c. The absolute ether was by then the presumed medium existing in vacuum by means of which light propagates. The absolute ether is considered to be at rest while all the stars and planets move in comparison to the absolute ether. When the ether cannot be influenced by anything than this ether is absolute. Only if the earth is at rest in the absolute ether then light will travel with equal speed in all directions. When the earth is moving in the absolute ether, the speed of light cannot be the same in all directions because the light moves in the ether in all directions with c. When the Earth moves relative to the ether on Earth the speed of light cannot be c in all directions because the light moves in the absolute ether in all directions with c; you cannot have both at the same time.

In experiments it was observed that the speed of light was always c in all directions. The dragged ether was denied and therefore the only possible form of ether left was the absolute ether. Because the Earth in her path around the Sun cannot always be at rest with the absolute ether there must be a physical process explaining why the Earth appears to be at rest with the absolute ether. The drag factor of Fresnel was a possible explanation.

Next chapter: The experiment of Fizeau

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