# QuestionWhy is snells law not considered in space

#### Clearmist

When I was in the navy we used sound underwater a lot, so much in fact that we had equations capable of mapping out a sound rays path.
Now, when it came down to mapping out the paths of sound the equations came from snells law. Snells law applies to ray paths in general. So both sound and light it applies to both. Now if you read up on Snell's law you may think it only applies to boundary lines. However from experience it applies to changes in density which happened to be boundary lines. However when you apply this to water the density changes throughout based on temperature pressure and salinity. Which eventually ends up applying Snell's law several times throughout the water curving the ray paths.

Now here comes my question how do we determine space density all throughout space to know whether or not light is or isn't bending by clear gas pockets? Why do we assume the density in space is uniformly the same? With no clear gas pockets for light to pass through and bend? It could be this phenomena that causes all light to bend in space and not gravity itself. Even the tiniest bend over light years away would throw off where we think stars are at by a considerable distance. Yet I haven't heard of anything to account for Snell's law in space.

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#### Helio

I don't want to suggest I fully understand this topic, but perhaps this will help get the ball rolling....

Snell's law, though I was once told it should be Snel's law, when applied to dense objects like glass and water addresses refraction due to wavelengths of sound or light. When molecules aren't essentially touching one another, then scattering effects better describe the pathways that result when light and sound are the propagating waves.

In space, as with our atmosphere, if the particles are smaller than than the wavelength being considered, then Rayleigh scattering is an accurate model to determine scattering propagation. If the particles are larger, usually significantly, then Mie scattering may be the best model.

In the case of Rayleigh scattering, the scattering effect is a 4th power rule, thus the 400nm (violet) wavelength photons will scatter about 16x more often than a 800nm (far red) photon. This is why we have a blue sky since those blue photons (the Sun is weak with violet and our eyes have trouble seeing violet) scatter in the atmosphere over our heads far more than the other wavelengths.

Mie scattering isn't very wavelength dependent though the pattern of the scattering favors forward and backward scattering more than side scattering, somewhat, IIRC. Clouds are a great example of this and another reason to argue the Sun is not a yellow star.

Sound underwater, given the huge number of molecules encountered, and the variations in density due to not only depth but temperature and, sometimes, salinity will refract. Sound in the upper atmosphere, with very little atmosphere, I assume, would make sonar all but useless.

Sound, surprisingly, can propagate through space because once molecules are combined to move in a given direction, then they will impact other molecules that allow the propagation to continue. I recall a Bb note (4 octaves below normal, IIRC) observed in another galaxy.

#### Geomartian

Snell’s Law and Space Time

Annual stellar aberration causes the apparent position of a star to change over a year. This is falsely attributed to some effect related to relativity. I believe Snell’s law might apply.

A static mass produces a gravitational field which can be mapped by clocks. Therefore, the temporal gradient in space produces a force on a mass. The temporal gradient is the cause, the force of gravity is the effect. This reverses the present dogma.

Inertia is a physical property of (real) space time.

When a fixed mass is subjected to a force, the gravitational field produced by that mass is distorted. This distortion creates a force on the mass to keep it in motion (falling into its own field?). For a small mass this temporal distortion cannot be practically measured.

For a mass the size and velocity of the Earth the temporal distortion caused by the inertial field is strong enough to distort both light rays and clocks.

The greatest stellar and temporal aberration occurs at the leading mass on the axis of motion. This is somewhere near the ecliptic pole.

Snell’s law is based on the speed of light in a medium. The speed of light is also directly affected by the speed of time in the space it is traversing (this is not related to relativity). If a light ray hits a temporal gradient at anything less than 90 degrees it will be deflected slightly. This is analogous to the angle of the air/lens interface.

Snell’s law (or a modified form) applied to stellar aberration should show the shape of the temporal distortion (spacetime lens) which is producing the aberration. In the case of annual stellar aberration, I believe the distortion may be caused by the Sun’s inertial field. Since the Earth is off to the side of the sun by about 150 million kilometers. We are looking through the edge of the Sun’s inertial “lens”.

As the Earth orbits the Sun the apparent position of the star near the ecliptic also shifts tracing a spherical or elliptical path over the year.

Snell’s Law still applies to spacetime.

#### Clearmist

Snell’s Law and Space Time

Annual stellar aberration causes the apparent position of a star to change over a year. This is falsely attributed to some effect related to relativity. I believe Snell’s law might apply.

A static mass produces a gravitational field which can be mapped by clocks. Therefore, the temporal gradient in space produces a force on a mass. The temporal gradient is the cause, the force of gravity is the effect. This reverses the present dogma.

Inertia is a physical property of (real) space time.

When a fixed mass is subjected to a force, the gravitational field produced by that mass is distorted. This distortion creates a force on the mass to keep it in motion (falling into its own field?). For a small mass this temporal distortion cannot be practically measured.

For a mass the size and velocity of the Earth the temporal distortion caused by the inertial field is strong enough to distort both light rays and clocks.

The greatest stellar and temporal aberration occurs at the leading mass on the axis of motion. This is somewhere near the ecliptic pole.

Snell’s law is based on the speed of light in a medium. The speed of light is also directly affected by the speed of time in the space it is traversing (this is not related to relativity). If a light ray hits a temporal gradient at anything less than 90 degrees it will be deflected slightly. This is analogous to the angle of the air/lens interface.

Snell’s law (or a modified form) applied to stellar aberration should show the shape of the temporal distortion (spacetime lens) which is producing the aberration. In the case of annual stellar aberration, I believe the distortion may be caused by the Sun’s inertial field. Since the Earth is off to the side of the sun by about 150 million kilometers. We are looking through the edge of the Sun’s inertial “lens”.

As the Earth orbits the Sun the apparent position of the star near the ecliptic also shifts tracing a spherical or elliptical path over the year.

Snell’s Law still applies to spacetime.

So your saying we can see all the locations that refract the light?
What I am saying that it is possible for the light of any particular star to be refracted thousand of times before it even reaches us. Every time the light goes through a small cloud of debris. Even if the light refracts just once or twice it would be possible to throw off a stars location in the sky by a considerable amount. Like when you see a fish in water it's location isn't where it appears and if that effect happens thousands of times how do you determine the fishs real location when we don't try to determine how many boundaries the light may be refacting off of.

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#### Helio

So your saying we can see all the locations that refract the light?
What I am saying that it is possible for the light of any particular star to be refracted thousand of times before it even reaches us. Every time the light goes through a small cloud of debris. Even if the light refracts just once or twice it would be possible to throw off a stars location in the sky by a considerable amount. Like when you see a fish in water it's location isn't where it appears and if that effect happens thousands of times how do you determine the fishs real location when we don't try to determine how many boundaries the light may be refacting off of.
Those are good points. There are a couple of things worth considering, I think. The number of photons that come our way are incomprehensible. The greatest flux density we have is looking, unwisely, directly at the Sun. Something like a million trillion photons enter the eye in one second so it would take a lot of particles to significantly effect what we see. This happens and there happens to be a nice article on this in this month's Sky and Telescope. [I haven't read much of it yet, admittedly.]

But I don't think refraction is the proper term else stellar disks -- we can observe a few -- would have weird colors I think. Scattering is likely what is happening. If the majority of the scattering is inelastic (not altering the path). Elastic scattering, IIRC, requires that the particles be smaller than the wavelengths in order to react with the photon directly enough to alter its direction. This happens for perhaps all reflection nebulae. They appear blue due to Rayleigh scattering (elastic).

#### serhiy1635

When I was in the navy we used sound underwater a lot, so much in fact that we had equations capable of mapping out a sound rays path.
Now, when it came down to mapping out the paths of sound the equations came from snells law. Snells law applies to ray paths in general. So both sound and light it applies to both. Now if you read up on Snell's law you may think it only applies to boundary lines. However from experience it applies to changes in density which happened to be boundary lines. However when you apply this to water the density changes throughout based on temperature pressure and salinity. Which eventually ends up applying Snell's law several times throughout the water curving the ray paths.

Now here comes my question how do we determine space density all throughout space to know whether or not light is or isn't bending by clear gas pockets? Why do we assume the density in space is uniformly the same? With no clear gas pockets for light to pass through and bend? It could be this phenomena that causes all light to bend in space and not gravity itself. Even the tiniest bend over light years away would throw off where we think stars are at by a considerable distance. Yet I haven't heard of anything to account for Snell's law in space.
The luminosity function or space density of galaxies, φ(L) is the number of galaxies in a given luminosity range per unit volume. This function is usually calculated from magnituded limited samples of galaxies with distance information. Distances to all but the nearest galaxies are determined from their radial velocities and the Hubble constant. (Note that in the Local Supercluster where the velocity field is disturbed by the gravity of large mass concentrations it is necessary to apply additional corrections to distances measured this way).Figure 10 is the differential luminosity function for field galaxies derived from a recent large survey of galaxy redshifts. The luminosity function is nearly flat at faint magnitudes and falls exponentially at the bright end.

#### newtons_laws

I don't want to suggest I fully understand this topic, but perhaps this will help get the ball rolling....

Snell's law, though I was once told it should be Snel's law,

Unless you happen to be French, then they call it Descartes' Law

#### newtons_laws

The interstellar environment is comprised of a low-density plasma of free electrons, known as the interstellar medium (ISM). The ISM affects pulsar observations by varying the observed pulse shape and flux of pulsars. One effect of the interstellar medium is that radio waves passing through it experience frequency dispersion, i.e high frequency radio waves travel through the interstellar medium along their path to Earth at close to the speed of light c, but the lower the frequency the slower their propagation speed (correctly speaking their group velocity which carries energy and information) is compared to c. The group velocity vg= c x n where n, the refractive index, is less than 1 (unlike the usual case when dealing with Snell's law in optical materials). The result of this frequency dispersion is that although a wide band of radio frequencies are emitted by a pulsar at the same time the higher frequency components reach the Earth before the lower frequency components arrive. http://ipta.phys.wvu.edu/files/student-week-2018/ism_lecture.pdf

#### vincenzosassone

Excuse me if I wrong, I'm passionate of astronomy but I'm not very good in this field, if the Snell's law is applied only in the places in which there is the matter, maybe seen that in the space there isn't matter, we can't speak about Snell's law. I have read some comments, but I have not understood a lot, and I made this idea.

#### Geomartian

Snell’s law is based on the refractive index of a lens. The refractive index is c/ refractive index. The speed of light slows down and that determines the angle that a ray of light will be bent at the air/glass interface.

A moving mass like the Sun produces a distortion in the space-time around it. That distorted space time is the origin of inertia. That distorted space time is equivalent to space having different rates of time. Even without matter, Snell’s law can be applied to the time rate differences in space-time to predict how much a light beam will be bent or refracted when it passes through this space.

You could apply Snell’s law to space-time with a calculator. If you try using General Relativity you might have a grossly incorrect answer in about a month.

Snell’s law describes space-time better than General Relativity.

You can also apply Snell’s law to the motion of a mass through space-time. Though I do not know how it applies to orbits since the values of inertia and kinetic energy might have different values depending on the properties of space in different parts of the orbit. It would still be simpler than GR.

#### vincenzosassone

Snell’s law is based on the refractive index of a lens. The refractive index is c/ refractive index. The speed of light slows down and that determines the angle that a ray of light will be bent at the air/glass interface.

A moving mass like the Sun produces a distortion in the space-time around it. That distorted space time is the origin of inertia. That distorted space time is equivalent to space having different rates of time. Even without matter, Snell’s law can be applied to the time rate differences in space-time to predict how much a light beam will be bent or refracted when it passes through this space.

You could apply Snell’s law to space-time with a calculator. If you try using General Relativity you might have a grossly incorrect answer in about a month.

Snell’s law describes space-time better than General Relativity.

You can also apply Snell’s law to the motion of a mass through space-time. Though I do not know how it applies to orbits since the values of inertia and kinetic energy might have different values depending on the properties of space in different parts of the orbit. It would still be simpler than GR.
Thank you so much, now this law is clearer and I understood a lot. But I have another doubt about the differences between GR and Snell's law. If these two laws are both corrected, why I would have problems using the GR instead of Snell's law? If both of them bring us in the correct way, why I wouldn't find the solution using one of them?

#### vincenzosassone

Snell's law is correct GR is meaningless.
Perfect, thank you so much for helping me, I'm a beginner...

#### Clearmist

Snell’s law is based on the refractive index of a lens. The refractive index is c/ refractive index. The speed of light slows down and that determines the angle that a ray of light will be bent at the air/glass interface.

A moving mass like the Sun produces a distortion in the space-time around it. That distorted space time is the origin of inertia. That distorted space time is equivalent to space having different rates of time. Even without matter, Snell’s law can be applied to the time rate differences in space-time to predict how much a light beam will be bent or refracted when it passes through this space.

You could apply Snell’s law to space-time with a calculator. If you try using General Relativity you might have a grossly incorrect answer in about a month.

Snell’s law describes space-time better than General Relativity.

You can also apply Snell’s law to the motion of a mass through space-time. Though I do not know how it applies to orbits since the values of inertia and kinetic energy might have different values depending on the properties of space in different parts of the orbit. It would still be simpler than GR.

We found out from the voyager probe that the vacuum of space isn't uniform. The density changes although it is a small change it means we can't verify density over light-years of distance. Anything clear, with a change in density, would refract light due to Snell’s law. Small pockets of clear gas etc. We have no way of verifying the density of space with clear gas, voyager probe shows this and this effect would dramatically change the star's real locations. We could be in a giant vacuum bubble for all I know and most of the universe is not in a vacuum. This would be a good explanation for dark matter for it could just be a lot more density in space throughout regions making more matter throughout regions of space causing higher gravity levels.

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