My explanation of gravitational lensing (not in relativistic view):

The electromagnetic field of a light photon in transit interacts with the gravitation filed of a massive celestial body between its transit paths, they exchange energy through their fields’ interactions depending upon their masses, as a result such a light photon gains energy in an arch like order as it passes said gravitational body. It is so obvious in the minds of any reasonable scientific persons.

Since the light photon, in transit, cannot increase its natural speed so it bounds to increase its energetic frequency, correspondingly it not only decreases it wavelength rather it increases its momentum too, as per relevant behaviour of photons (𝑝 = ℎ/𝜆).

However, the light photon doesn’t store the energy that it’s gaining temporarily, rather it releases the energy gaining by way of converting it into its momentum, this makes the photon’s path of interaction an arc like, therefore the light photon again continues its journey in a straight path, as soon as it releases temporarily gained energy. This is how gravitation lens work.

#GravitationLens

Brief explanations in expansion, acceleration, dark energy, antigravity etc

Reasonably, a natural thing can physically expand or change in distance, but none can physically expand, say, an idea of addition or deduction or multiplication etc. similarly, not space or time, since space is an infinite three-dimensional extent, where objects and events contain relative position and direction. And dimension is an extension of the abstract concept of mathematics. For example, a line is one-dimensional, a plane is two-dimensional and space is three-dimensional. Therefore, space is not an entity but an abstract concept.

Since space is a concept in extension of height, width and depth, accordingly it is described in the earlier post that space itself cannot expand, but what expanding is the distances among relevant galaxies.

The reason for acceleration is mentioned in the post, "antigravity is stronger than gravity," where dark energy or antigravity cause by dark energy practically has no influence within a galaxy up to the zero gravity sphere around a galaxy. Dark energy rules beyond zero gravity sphere and so antigravity is effective not only beyond a galaxy but also beyond the galaxy's zero gravity sphere around it.

However, what in the background is that the effective mass of dark energy is <0 and so it causes antigravity and the strength of antigravity is stronger than gravity as one approaches towards the edge of the visible universe.

The anti-gravitational field interacts with the gravitational fields of gravitationally bound galaxies - in tug of wars. But there is no effect of dark energy within a gravitationally bound galaxy.

Since effective mass of antigravity is much stronger than the effective matter mass of gravity in the universe, including the dark matter, expansions in the distances among galaxies accelerate as they recede towards the edge of the visible universe, and it is inevitable.

Reference Original Post

#antigravity #expansion #darkenergy #darkmatter

Why the speed of light is constant?

Einstein considered the theoretical aspects. It can be derived from Maxwell's equations that the speed at which electromagnetic waves travel is: 

c = (ϵ0μ0)^(−1/2) = 1/√ϵ0μ0.

Since light is an electromagnetic wave, that means that the speed of light is equal to the speed of the electromagnetic waves. 

ϵ0 and μ0 are properties of the vacuum and are constants, so c will also be a constant.

According to Maxwell equations, an electromagnetic wave moving with velocity 

v = 1/√ϵ0μ0. 

Since light is an electromagnetic wave, that means that light is also propagating at this speed in vacuum. 

And since both ϵ0 and μ0 are constant, that means 1/√ϵ0μ0 is also a constant. Hence light moves at a constant speed in vacuum. 

#Maxwell 

Expansion of space is rather expansion of distance.

Space is an infinite three-dimensional extent, where objects and events contain relative position and direction. Dimension is an extension of the abstract concept of mathematics. For example, a line is one-dimensional, a plane is two-dimensional and space is three-dimensional. Therefore, space is not an entity but an abstract concept.

Expansion of space is rather expansion of distance among distant gravitationally bound objects within dimensions of space:

More specifically, spatial expansion is the increment in the distance between two distant points in the dimensions of space, at least in intergalactic scale. This is increment in distance in metric scale, where space itself does not expand. Space is rather the metric scale. 

Dark energy appears to act like antigravity, so antigravitational field interacts with gravity of gravitationally bound objects within dimensions of space, where antigravity is stronger than gravity, and so the galaxies recede from one another, and that increases distance between two distant points within the dimensions of space.

Reference Explanation

#Intergalactscale #distanceincrement #expansion #antigravity #antigravitationalfield

How redshifts Occur?

[Author ORCID: 0000-0003-1871-7803]

The infinitesimal losses in wave energy (ΔE) due to various effects like gravitational, spatial expansion or Doppler, correspond to phase shifts of the wave in degree (°) resulting time shifts (Δt) and corresponding enlargement in the wavelength (Δλ) of the wave, this is how redshift occurs in general.

The value of a redshift is denoted by the letter z, corresponding to the fractional change in wavelength, positive for redshifts, negative for blueshifts, and by the wavelength ratio 1 + z, which is >1 for redshifts, <1 for blueshifts. And so, red-shift (z,>1) is the displacement of spectral lines towards longer wavelengths (Δλ+λ)>λ i.e. the red end of the electromagnetic spectrum.

The wavelength λ of a wave is directly proportional to the time period T of the wave (λ ∝ T), and energy of the wave (E) is directly proportional to the frequency of the wave (E ∝ f).

The time interval for 1° of phase is inversely proportional to the frequency (f). If the frequency of a signal is given by f, then the time t (deg), in seconds, corresponding to 1° of phase is t (deg) = 1/(360f) = t/360. Therefore, a 1° phase shift on a 5 MHz signal corresponds to a time shift of 555 picoseconds (ps).

Accordingly, the corresponding increments in degree (°) phase shifts on a given signal frequency, there is increment in time shifts (Δt).

Therefore, the redshifts occur through the phase shift in wave frequency due to infinitesimal loss in wave energy (ΔE) and corresponding enlargement in the wavelength (Δλ) of the wave. 

Various Redshifts

The electromagnetic radiation, like light, from distant galaxies and celestial objects, interpreted as a Doppler shift that is proportional to the velocity of recession and thus to distance of the galaxy.

Moreover, the universe is expanding, and that expansion stretches the wavelength of light traveling through space in a phenomenon known as cosmological redshift.

Furthermore, there is gravitational redshift, also known as Einstein shift; it is the phenomenon that electromagnetic waves or photons traveling out of a gravitational well lose energy, this corresponds to longer wavelengths (λ)

Ther three known types of redshifts are, Doppler redshift, Gravitational redshift and Cosmological redshift.

1. Doppler redshift, a phenomenon observed in the context of the Doppler effect. The Doppler effect describes the change in the frequency or wavelength of a wave as a result of the relative motion between the wave source and the observer.

• Z = {λ(obs)-λ(rest)}/λ(rest); where,

Z denotes the redshift factor which represents the fractional change in wavelength;
λ(obs) represents the observed wavelength of light;
λ(rest) represents the rest wavelength of light;

In the context of light, Doppler redshift refers to the observed increase in wavelength (or decrease in frequency) of light from a source moving away from the observer. The formula given above calculates the redshift factor, denoted "Z", which represents the fractional change in wavelength.

In the formula, λ(obs) represents the observed wavelength of light, while λ(rest) represents the remaining wavelength of light, which is the wavelength that would be measured if the source were stationary relative to the observer.

By comparing the observed wavelength with the rest wavelength, the Doppler redshift can be determined, which indicates the relative motion between the source and the observer. A positive value of Z indicates that the source is moving away, causing the observed wavelength to become longer (red-shifted), whereas a negative value of Z indicates motion toward the observer (blue-shifted).

Doppler redshift has important applications in many fields of science, including astronomy, where it is used to study the motion and expansion of celestial objects such as galaxies and large-scale structures in the universe. It provides valuable information about the velocity and distance of these objects based on observed changes in their spectral lines.

2. Gravitational redshift, denoted Z, is a phenomenon predicted by the theory of general relativity. This refers to the change in wavelength (or equivalently, frequency) of light as it travels through a gravitational field, such as near a massive object.

•  Z = Δλ/λ₀; where,

Z denotes the redshift factor which represents the fractional change in wavelength;

Δλ is the change in wavelength of light as observed;

λ₀ is the wavelength at the source.

As light travels through a gravitational field, it loses energy in the light, causing it to shift to longer wavelengths (or lower frequencies). The formula given above calculates the redshift factor, denoted "Z", which represents the fractional change in wavelength.

The magnitude of the gravitational redshift depends on the strength of the gravitational field experienced by the light and the proximity of the massive object. The closer the light source is to a massive object, or the stronger the gravitational field it crosses, the greater the redshift observed.

Gravitational redshift has been observed and measured in a variety of contexts, such as in experiments conducted on Earth and through astronomical observations. This provided evidence for the gravitational nature of light and confirmed predictions of gravitational fields.

3. Cosmic redshift (Z) is a phenomenon observed in astronomy in which light emitted from distant celestial objects such as galaxies or quasars is shifted to longer wavelengths (lower frequencies) as it travels through expanding distance. This is the result of the expansion of distance among the objects in the universe. 

• Z = Δλ/λ₀; where,

Z denotes the redshift factor which represents the fractional change in wavelength;

Δλ is the change in wavelength of light as observed;

λ₀ is the wavelength at the source.

According to the conventional cosmological model, the Big Bang theory, the universe is constantly expanding. As space expands, it carries light waves with it, causing them to expand and resulting in a red shift. The formula given above calculates the redshift factor, denoted "Z", which represents the fractional change in wavelength.

The magnitude of the cosmic redshift is directly related to the distance between the observer and the light source. The farther away an object is, the more space it has traveled during its journey and the greater the observed cosmic redshift.

Cosmic redshifts have been observed and measured in countless astronomical observations, providing strong evidence for the expansion of the distance within the universe. The redshift of distant galaxies was first observed by Edwin Hubble in the 1920s, leading to the discovery of the expanding distance within the universe and the formulation of Hubble's law, which describes the relationship between the redshift of galaxies and their distance from us.

Cosmological redshift is an essential tool in studying the large-scale structure and evolution of the universe. It allows astronomers to estimate the distances to remote objects, determine the expansion rate of the universe (Hubble constant), and investigate the nature of dark energy, which is believed to be driving the accelerated expansion of the distance within the universe.

Spectroscopy (Additional)

The spectroscopy is used as a tool for studying the structures of atoms and molecules. The large number of wavelengths emitted by these systems makes it possible to investigate their structures in detail, including the electron configurations of ground and various excited states. From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving.

#Redshift #gravitationalredshift #spatialexpansionalredshift #dopplerredshift #wave #WaveEnergy #LossOfWaveEnergy