THE EXPANSION OF THE UNIVERSE MAY BE AN ILLUSION CREATED BY COMPTON SCATTERING OF FREE ELECTRONS

The high-precision measurements of the Hubble parameter make the theory of cosmic expansion more and more confusing, which bolster the idea that new physics may be needed to explain the mismatch. The cosmological redshift may not only be related to distance but also to other factors. The expansion of the Universe may be just an illusion. The Compton effect of free electrons and low energy photons has been observed in the laboratory. This article proposes a theory: Free electron Compton scattering (FEC) produce the illusion of the Universe exponential expansion: FEC causes photons to redshift (FEC redshift), and the photon beam expands along the propagation direction, that is, the redshift factor is (1 + z ) ; the beam length stretch factor (time dilation of the supernova curve) is (1 + z ) ; the expansion factor of the beam volume is (1 + z ) 3 , and FEC will not be blurred Distant galaxy. The reason for rejecting the “tired light”does not hold in FEC..


INTRODUCTION
In 1927, the Belgian astronomer and cosmologist Georges Lemaître first proposed the Big Bang hypothesis. In 1929, the American astronomer Hubble proposed Hubble's law based on the redshift of galaxies being proportional to the distance, and deduced the theory of the expansion of the Universe that galaxies are far away from each other. In 1946, American physicist Gamow formally proposed the big bang theory. The explosion theory believes that the Universe was formed by a big explosion that occurred about 13.8 billion years ago. At the end of the last century, observations of the Ia supernova showed that the Universe was accelerating, and the energy for accelerating expansion came from dark energy. The Big Bang theory successfully predicted the microwave background radiation (CMBR) and cosmic abundance, which became an important support for the theory of cosmic expansion. The theory of Universe expansion has been widely recognized by the scientific community.
1. The relationship between the redshifts z and distance: z = exp (H 0 D/c) − 1, where H 0 is the Hubble parameter; D is the co-moving distance; c is the speed of light.
2. Time dilation of supernova light curves (time dilation). (Goldhaber et al. (2001); Blondin et al. (2008)) 3. The relationship between the spectrum of CMBR and its energy density. Wright (2008) 4. "The Tolman Surface Brightness Test for the Reality of the Expansion: the surface brightness of a set of standard (identical) objects will decrease by (1 + z) 4 . One factor of (1+z) comes from the decrease in the energy of each photon due to the redshift. The second factor comes from the decrease in the number-flux per unit time. Two additional factors of (1 + z) come from the apparent increase of area due to aberration." Lubin & Sandage (2001) These support the theory of cosmic expansion: the Universe expands exponentially. The redshift factor is (1 + z); the volume expansion factor is (1 + z) 3 . The Hubble parameter is the most important parameter in modern cosmology, which is the basis of age, size and evolution of the Universe. Measurements over the past century have shown that Hubble parameters are not a constant. Riess et al. (2019) based on observations of 70 long-period Cepheids in the Large Magellanic Cloud and give the latest value of 74±1.42 km s −1 Mpc −1 with an error margin of just 1.91%. The Hubble parameter indirectly arising from the CMBR is 67.8 km s −1 Mpc −1 . The two most precise gauges of the Universe's expansion rate have recently been in glaring disagreement (Garner (2019);Castelvecchi (2019); Freedman et al. (2019); Marra et al. (2013)). Freedman et al. (2019) give a value of 69.8±0.8(±1.1%stat)±1.7(±2.4%sys) km s −1 Mpc −1 based on a calibration of the tip of the red giant branch (TRGB) applied to Type Ia supernovae (SNE Ia) with a sample containing about 100 well-observed SNe Ia. The Hubble parameter measured by Chen et al. (2019) based on Quasar is the largest.
The high-precision measurements of the Hubble parameter make the theory of cosmic expansion more and more confusing (Castelvecchi (2019) (2019)).
From the measured values of these Hubble parameters above, we can find: There are systematic discrepancy in the Hubble parameter of different types of stars (types of light sources: Cepheids; CMBR; SNe Ia.; Quasar), which means that the Hubble parameter is not only related to the distance but also to the types of stars considered.
There are also many problems with the theory of expanding Universe, such as the Hubble constant (Hubble parameter) is not a constant; the dark energy is nowhere to be found.
Therefore, Hubble's law may be an approximation, the Universe expansion theory based on Hubble's law may be wrong, and the expansion of the Universe may be just an illusion. The new physics may be: The Compton scattering of free electrons creates the illusion of the Universe expansion. See Figure1. Whether the Universe really expands has been controversial. Zwicky (1929) made the first alternative proposal ("Tired Light"). He proposed that the redshift is not due to the expansion of the Universe, but the effect of the Intergalactic medium that causes the photon energy to decrease. Lubin & Sandage (2001) "Tired light"can explain the redshift, but can't explain items 2; 3; 4 in this section. Compton models are in the class of "Tired light"cosmic models. FEC has a clear physical mechanism, will it be the same as "Tired light"? No! Compton scattering usually refers to the interaction of high-energy photons and bound electrons, which may produce a large scattering angle. This leads no one to think that the redshift of cosmology is caused by Compton scattering. (Zwicky (1929);Wright (2008)) 2. METHODS

FEC
FEC refers to Compton scattering of free electrons and low-energy (low-frequency) photons. The characteristic spectral lines mainly exist in low-frequency band. The electron is free, not bound. The Compton effect of low-energy photons and free electrons is very weak and neglected.
When a photon interacts with a large number of electrons, each scattering angle θ i is very small. The random scattering angles cancel each other, it spreads approximately in a straight line along the original propagation direction. The final angle of each photon entering the observer is ( ∑ θ i ) j (Subscript j marks different photons), the probability distribution of ( ∑ θ i ) j is Gaussian distribution, the axis (µ = 0) is the line connecting the light source and the observer. Therefore, the FEC effect will not cause the images of distant galaxies to become blurred. As the redshift z increases, the aberration also increases.
When the interaction is between relatively cold CMBR photons and hot free electrons, it is known as the thermal Sunyaev-Zel'dovich effect (Inverse Compton effect), the cold CMBR photons are blueshifted (Carlstrom et al. (2002); Malu et al. (2017)). When the interaction is between relatively hot photons and cold free electrons, will relatively hot photons be redshifted by cold free electrons?
Nonlinear Compton scattering has been observed when several photons from a high-intensity low-frequency (lowenergy photons) laser beam are scattered by a free electron to produce a photon of different energy, this process has been calculated theoretically and successfully measured (Brown & Kibble (1964); Moore (1995); Babzien et al. (2006); Loetstedt & Jentschura (2009)). These show that low-energy photons have not only wave properties but also particle properties,This means that both high-energy photons and low-energy photons interacting with free electrons will undergo Compton scattering.
figure.2.The interaction between free electrons and photons: the electrons are affected by the force ⃗ F of electromagnetic radiation, can be regarded as the current or displacement current generated by the movement of electrons. When the initial velocity of electron is neglected, the electron is always affected by the electric field force ⃗ F E and moves perpendicular to the ⃗ K-direction, so the electron always suffers recoil in the ⃗ K-direction by ⃗ F B , and Photon recoil is opposite to the ⃗ K-direction. When the photon is low-energy, ⃗ F B ≪ ⃗ F E , ⃗ F B is ignored, the electron recoil and the photon recoil are ignored because they are too small, the process is called Thomson scattering. Otherwise, it is called Compton scattering. When the free electron is in the high-intensity low-frequency laser field, the frequency of the radiation field is high enough to make the electron velocity relativistic, ⃗ F B cannot be ignored, the electron recoil is obvious (Brown & Kibble (1964); Moore (1995); Babzien et al. (2006); Loetstedt & Jentschura (2009)). So when the free electron is in the lowintensity low-frequency field,although ⃗ F B ≪ ⃗ F E and ⃗ F B can be ignored, but ⃗ F B exists, Compton scattering exists, but it is too small to be observed and is ignored,the wavelength of scattered photon is almost the same, and the energy loss of the photon can be ignored. When photons interact with a large number of free electrons,FEC effect appears:Photons are redshifted and the photon beam is expanded by FEC along the propagation direction.
where h is Planck constant; m e is the electronic mass; c is the speed of light; θ is the scattering angle; the initial velocity of the electron is ignored, the electron is completely free. δλ and θ are independent of the wavelength of the photon, δλ is only related to θ. Compton shift is inversely proportional to the mass of charged particles, so the Compton shift is mainly caused by the electrons. When a photon collides with a large number of electrons repeatedly, FEC redshift: Where z i is the FEC redshift caused by the i-th collision, N is the total number of collisions; ⟨1 − cos θ i ⟩ is the average of (1−cos θ i ). Eq. (1) is established under the condition that the wavelength change caused by the collision is negligible. Since photon is plane electromagnetic wave (Brown & Kibble (1964); Moore (1995); Babzien et al. (2006)), N is proportional to the wavelength λ and optical path D and electron density n e , let K ∝ h/m e c × ⟨1 − cos θ i ⟩ we get: That is to say, cosmological redshift and Hubble parameters are not only related to distance, but also related to corresponding electron density. Where K (unit: m 2 ) is a coefficient, when the electron density increases, the coupling force between electrons and other charged particles increases, and K decreases; when the electron temperature T e increases, the temperature of photon relative to electron decreases, and the K value decreases. Eq.(3) is still unknown.
Since θ is independent of the wavelength of the photon, so K and Z FEC are independent of the wavelength of the photon as well, similarly as for the Doppler effect, it is sometimes difficult to distinguish them.
The condition for Eq.
(2) to be satisfied is Z FEC ≪ 1, moving to high redshifts: Due to the existence of the scattering angle and the difference in size, the paths of different photons are different, and the beam is expanded, See figure 1). Set l as the one-dimensional scale parameter of the beam. Similar to equation (4), then: therefore, the factor of one-dimensional length expansion of the beam is (1 + Z FEC ) ; the factor of two-dimensional plane is (1 + Z FEC ) 2 ; the factor of three-dimensional volume is (1 + Z FEC ) 3 .  2016)). The gravitational redshift of the Sun is known to be less than 1 km s −1 Joyce et al. (2018). When solar flares occur, their spectral profile has a redshift asymmetry that is difficult to explain with the Doppler effect. The redshift asymmetry rules out the Stark effect because Stark-induced shift occurs in dense plasma (plasma with electron concentration about and above Halenka et al. (2015)). The electron density of solar flares is generally in the range of 10 12 -10 14 cm −3 (Kerr et al. (2018), Reep et al. (2019)). When solar flares occur, the temperature of the solar atmosphere increases and ionization increases. A typical characteristic is that the spectral profile of the solar flare is significantly broadened and simultaneously redshifted. In flare AR 12205 Akiko et al. (2018), there is a clear evidence of the relationship between the spectral broadening, the redshift, and FEC redshift. It excludes the Doppler effect.

Evidence of FEC redshift in Flare redshift
In flare AR 12205 Akiko et al. (2018). The formation temperature of Si IV 1403Å, C II 1335Å, Mg II h 2803Å, H α 6563, CA II K 3934Å, CA II 8542Åin logT [k] is 4.8, 4.3, 4.0, 4.0, 4.0 and 4.0, from the highest to the lowest. The distance between the spectral line forming region and the core of the flare increases and the influence of the flare decreases. These are consistent with the spectral line width Akiko et al. (2018).
The flare energy comes from the interior of the photosphere:1. The flare erupts in the lower part of the chromosphere;2. The fermi 29-31,50-102 keV erupts earlier than 17 GHz (fast radio burst) for about 10 s at the highest pointAkiko et al. (2018), which indicates that the energy comes from fermi 29-31,50-102 keV. If the energy comes from the external high-energy electron beam, the electron beam will inevitably collide with the chromosphere particles during transportation to produce bremsstrahlung and heat the surrounding material, the 17 GHz and 1-8Åsignals are earlier than for fermi 29-31, 50-102 keV and the trajectory of the electron beam should be observed before the flare eruption, but the electron trajectory has not been obtained Akiko et al. (2018).
The radiation at 1-8Åis caused by the free thermal electronsAkiko et al. (2018). When the first burst of feimi 29-31 keV (T = 150-200 s) occurred, there were no significant corresponding bursts at 1-8Å, due to the lack of free electrons in the chromosphere at the beginning of the flare. The radiation at 1-8Ågradually increases when the thermal expansion, the number of free electrons, and the temperature of the electrons increase. When the second burst of fermi 29-31 keV (T = 240-360 s) occurred, 1-8Åfollowed fermi 29-31keV, the spectrum lines Si IV 1403Å,C II 1335Å, Mg II h 2803Å, Ha 6563Åbegan to broaden and redshift at the same time (See theAkiko et al. (2018)). The onset and the duration of the apparent broadening and redshift of these lines are consistent with the 1-8Åradiation. This indicates that: 1. The apparent broadening and the redshift of these lines fully correlates with the increase number of free electrons. 2. The apparent broadening and redshift of these spectral lines is not caused by the Doppler effect from particle motion, but by FEC because the change in particle velocity caused by the thermal expansion takes time and the radiant ionization makes the free electrons increase immediately.
A possible explanation for the red asymmetry is proposed. After the flare occurs, the thermal expansion (the Balmer and Ca II H lines showed blue asymmetry Doppler effect Akiko et al. (2018)), and the number of free electrons gradually increases. The FEC effect also gradually increases, and the spectral linewidth gradually broadens (Akiko et al. (2018); Kerr et al. (2015)). When the FEC effect is larger than the Doppler effect, the blue asymmetry changes to a red asymmetry. The redshift occurs at the position where the intensity is highest and tracks the outer edge of the ribbon, which visually illustrates this phenomenon Kerr et al. (2015). Similar phenomena include the high redshift of gamma-ray bursts (Choudhury & Srianand (2002); Campana et al. (2011)).
The FEC redshift and the Doppler effects were used to simulate the spectral line velocity in flare AR 12205. The electron density of the flare was in the range of 10 12 -10 14 cm −3 , log T e [k]= 4 -4.5 (Kerr et al. (2018); Reep et al. (2019)), the value of K was roughly estimated around.

RESULTS
FEC causes photon redshift and photon beam expansion: 1. FEC will not blur the imaging of distant galaxies.
2. The FEC redshift is not only related to the distance but also to the corresponding electron density, this can explain why the Hubble parameter is not a constant.
If CMBR was not formed by the Big Bang, how was CMBR formed? CMBR is almost perfect 2.725K blackbody radiation Fixsen et al. (1996). The big bang theory successfully predicts CMBR and the relationship of the local CMBR temperature T 0 and the CMBR temperature T z (where the redshift is z), T z = T 0 × (1 + z) (Noterdaeme et al. (2009);Noterdaeme et al. (2011)).
The assumption of this paper is:The local CMBR (T 0 ) is mainly created by large-scale interstellar medium (Mainly Interstellar neutral atoms, molecules, dust) radiation ( T z ), due to the FEC effect, the photon density of CMBR ( T z ) is diluted by (1 + z) 3 times and the temperature T z is reduced by (1 + z) times. The temperature T z of the interstellar medium is about 10-100K. The interstellar medium in the Universe is almost uniform and isothermal, and local is transparent, when the distance is greater than z = 4.7, the interstellar medium gradually formed a fog and progressively made the Universe opaque, forming a blackbody with a temperature of T z . In this way, CMBR comes from the distant Universe(z > 4.7) Wright (2008).
Most of the energy of starlight is absorbed by the intergalactic and the interstellar medium, and a small part of it becomes microwave background radiation. The intergalactic medium and the interstellar medium absorb the radiation energy and emission radiation. CMBR is formed indirectly by starlight, which is diluted and redshifted by the FEC effect.
It can be derived from the FEC cosmic model that the emissivity of CMBR is greater than 1. The emissivity of the Universe expansion theory will be less than 1 due to space expansion. The best fit emissivity is 1.09 Wright (1997). The number of faint radio sources of the FEC model will increase, and of cosmic expansion mode will decrease and dilute. The number of faint radiation sources can distinguish FEC model and the Universe mode. For more details, see: Wright (2015) 4.

DISCUSSION
The FEC redshift depends on the free electron fraction, is it constant in the Universe? On a large scale, CMB has a perfect blackbody radiation and an almost perfect isotropy Ben-Dayan et al. (2014), indicating that the intergalactic medium has an almost uniform temperature and that the density of intergalactic electrons is almost uniform and isotropy as well. Dispersion measurements (DM) of fast radio bursts (FRB) also indicate that the density of intergalactic electrons is almost uniform on a large scale, and may be related to the redshift (Katz & J. (2016); Yao et al. (2017);Ashmore (2016))If the Hubble parameter not only depend on the distance fraction but free electron fraction then FEC redshift can perfectly explain why the Hubble parameter is isotropy but not perfect isotropy. Stars, red giants, Cepheid variable stars, supernovas, and quasars have a different atmospheric electron density, which leads to deviations in the Hubble parameter for different samples. A higher star mass results in a higher temperature and a larger the redshift. This is why the Hubble parameter measured based on CMB and the red giants and Cepheid variable stars are different. This is also why quasars are abnormally redshifted (Dai et al. (2012); Chu (1981)) and why the Hubble parameter measured over a century is not "constant". Because Eq. (3) is unknown. Hypothesis: the K of the intergalactic electrons is the same as the K = 2 × 10 −28 m 2 of the flare electrons, the average electron densityn e (H 0 ) (obtained by this theory that produces H 0 67.8 km s −1 Mpc −1 ) is around 4 × 10 −5 cm −3 . The interstellar electron density is within 1-10 −3 cm −3 (Katz & J. (2016); Yao et al. (2017)), therefore the average intergalactic electron densityn IGe (H 0 ) is less than 4 × 10 −5 cm −3 . This value is much greater than the present value of the critical density, but if the Universe is infinite, then the critical density is meaningless. The intergalactic electron densityn IGe (DM ) obtained from the DM of fast radio bursts is about 10 −7 cm −3 (Katz & J. (2016); Yao et al. (2017)). The reason for the radiation broadening of DM is that the scattering is caused by a thin slab of fluctuating electron density (Katz & J. (2016); Williamson & Scheuer (1973)), therefore the value of 10 −7 cm −3 is not the true intergalactic electron density, is greater than10 −7 cm −3 . Son IGe (H 0 ) < 4 × 10 −5 cm −3 is also reasonable.

CONCLUSION
The Compton effect of free electron and low-energy photons has been observed in the laboratory. As long as there is a reasonable density of free electrons in the Universe, the FEC effect will exist. FEC redshift and FEC cosmic model may work.
The author is grateful to Mark Krumholz for guidance, Edward L. Wright and A. Tei, et al. for sharing their knowledge and analyzing their observations.