Quark stars, black holes, and invisible light. (How gravity stretches light)

How gravity stretches light? 

Can some red dwarfs be quark stars? Quark star's gravity, or virtual (gravitational) Doppler effect stretches light so much, that it can turn to look like red. 

"A quark star is a hypothetical type of compact, exotic star, where extremely high core temperature and pressure have forced nuclear particles to form quark matter, a continuous state of matter consisting of free quarks." (Wikipedia, Quark Star) 

"The Doppler effect (also Doppler shift ) or Redshift is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The Doppler effect is named after the physicist Christian Doppler, who described the phenomenon in 1842. (Wikipedia, Doppler effect)

A common example of Doppler shift is the change of pitch heard when a vehicle sounding a horn approaches and recedes from an observer. Compared to the emitted frequency, the received frequency is higher during the approach, identical at the instant of passing by, and lower during the recession. " (Wikipedia, Doppler effect)

What if something stretches radiation as much as its wavelength turns straight? Black holes can make that thing near their event horizon. That is one of the most important things in the black holes' gravitational effects. The massive or extremely strong gravitational field stretches light so much that we cannot see even the event horizon. 

An animation illustrating how the Doppler effect causes a car engine or siren to sound higher in pitch when it is approaching than when it is receding. The red circles represent sound waves. (Wikipedia, Doppler effect) 

There is no limit to how much the redshift can stretch light or wavelength. There is a possibility that strong gravity fields along fast movement away from the observer can stretch the light straight to radio waves. But can this kind of extreme Doppler effect be possible? 

Strong gravity fields can cause the Doppler effect that visible light spectrum goes to the electromagnetic spectrum's red side. When the Doppler effect stretches radiation it makes the same thing as the strong gravity field. A strong gravity field can transfer all visible radiation that comes from an object into the IR area and that can cause interesting theory. 

"Absorption lines in the visible spectrum of a supercluster of distant galaxies (right), as compared to absorption lines in the visible spectrum of the Sun (left). Arrows indicate redshift. Wavelength increases up towards the red and beyond (frequency decreases)." (Wikipedia, Redshift)

"In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift, or negative redshift. The terms derive from the colours red and blue which form the extremes of the visible light spectrum. " (Wikipedia, Redshift)

"The main causes of electromagnetic redshift in astronomy and cosmology are the relative motions of radiation sources, which give rise to the relativistic Doppler effect, and gravitational potentials, which gravitationally redshift escaping radiation. All sufficiently distant light sources show cosmological redshift corresponding to recession speeds proportional to their distances from Earth, a fact known as Hubble's law that implies the universe is expanding." (Wikipedia, Redshift)

"Illustration of the interior of a neutron star and a strange quark star" (Wikipedia, Strange star)

"A strange star, also called a strange quark star,  is a hypothetical compact astronomical object, a quark star made of strange quark matter." (Wikipedia, Strange star)

"Strange stars might exist without regard to the Bodmer–Witten assumption of stability at near-zero temperatures and pressures, as strange quark matter might form and remain stable at the core of neutron stars, in the same way as ordinary quark matter could. Such strange stars will naturally have a crust layer of neutron matter. The depth of the crust layer will depend on the physical conditions and circumstances of the entire star and on the properties of strange quark matter in general. Stars partially made up of quark matter (including strange quark matter) are also referred to as hybrid stars." (Wikipedia, Strange star)

The collapse of the crust layer of strange stars is one of the proposed causes of fast radio bursts." (Wikipedia, Strange star)

Electromagnetic Spectrum 

It's possible. That hypothetical quark stars look like red dwarfs. That makes them so-called red false dwarfs. Or maybe it can stretch radiation so much that the visible light's wavelength moves to IR or even radio wave areas in the electromagnetic spectrum. We know that strong gravity fields cause a virtual Doppler effect that makes the wavelength stretch. 

Can some red dwarfs be those hypothetical quark stars? If a quark star's gravity is strong enough it can turn the object red. So how can we prove that thing? Red dwarfs are small and light stars. So to confirm that the object that we think of as a red dwarf is the quark star we need to find a binary star where white dwarfs or neutron stars orbit the red dwarf. 

Normally neutron star or white dwarf is the mass center. The mass center is the gravity center. That means normally red dwarfs orbit white dwarfs or neutron stars. But if that happens oppositely. That red dwarf is the mass center which means its gravity can be so strong that it stretches light into red. 

But same way one, very heavy but hypothetical object called a quark star can stretch light. Can it be possible that the hypothetical quark stars have so strong gravity field, that they can stretch or turn even UV radiation into radio waves? 

In some models, the quark star can be invisible. The idea is that the quarks form the quark star's shell. Quark stars would be the only places in the universe where quarks are free. In other places. Those particles are tied inside hadrons. The reflection that comes out from the quark stars comes from quarks. In regular material. That reflection comes from hadron quantum fields. It's possible that radiation that hadrons send just slides over the quark star. 

Or the particle that causes reflection is so small that we cannot see that thing in a quark star. If energy reflection comes straight from a quark it travels straight through Hadron. There is the possibility. That also other fields. Except gravity slides over those quarks. That form structure. That seems like it's covered by small half-balls. When energy travels or slides over the structure it denies reflections in wavelength that we can see it. 

There is a model that quark stars are mediums between neutron stars and black holes. The thing is that those hypothetical quark stars can stretch radiation as much as their wavelength turns so long that we cannot see it. 

Or we cannot detect that radion because some other things cover it. In some models, photons can travel through those free quarks. The gravity field around those hypothetical quark stars would be powerful. But that gravity field stretches radiation and it can make it possible for the quark star can be invisible to the human eye. 

https://www.helsinki.fi/en/news/mathematics-and-science/finnish-researchers-have-discovered-new-type-matter-inside-neutron-stars

https://sciencesprings.wordpress.com/2024/01/04/from-the-university-of-helsinki-helsingin-yliopisto-fi-via-phys-org-further-evidence-for-quark-matter-cores-in-massive-neutron-stars/

https://en.wikipedia.org/wiki/Doppler_effect

https://en.wikipedia.org/wiki/Electromagnetic_spectrum

https://en.wikipedia.org/wiki/Quark_star

https://en.wikipedia.org/wiki/Redshift

https://en.wikipedia.org/wiki/Strangelet

https://en.wikipedia.org/wiki/Strange_star