The concept of an expanding universe originated as an explanation for the observed red shift of light from distant galaxies. When Edwin Hubble found that the wavelength of light from certain galaxies is a linear function of their distance from the earth he related this to the velocity of expansion.  Hubble's law states that the velocity of expansion increases linearly with the distance from the earth to a galaxy.         

 

This law has been accepted for more than a century but in recent years it has become more and more difficult to justify. As more astronomical data is accumulated, more problems arise and more explanations are offered, including the proposition that expansion is powered by a mysterious "dark energy". At the present time many other aspects of theoretical physics are under attack.

 

Isaac Newton was concerned that he could not explain the existence of gravitational force in the vacuum of space, but today we know that the space between stars is not empty (Ref.1). Quantum theory tells us that space throughout the universe is filled with vacuum energy from which particles are generated. Albert Einstein defined space as a flexible entity which reacts with mass and accounts for the force of gravity.

 

A much simpler approach to the nature of space and mass can be found by combining some elements of the above theories. If space is assumed to be a universal ideal elastic medium in which mass is related to strain energy and light travels as a transverse stress wave, then both protons and stars can be defined as spherical stress patterns (Ref.2).

 

The red shift of light emitted by a star is then a characteristic of the stress pattern of the star and is not related to the motion of the star. In addition, both gravitational and electrostatic forces can be accounted for by the superposition of stresses. Also, stress patterns are not of finite size, which  may explain entanglement.

   

The work described in Ref.2 used only applied mechanics and Einstein's law of equivalence to establish the characteristics of the stress patterns of both protons and stars, thus avoiding the lack of connection between quantum theory and general relativity.   

 

Ref.1     https://www.space.com/is-the-vacuum-of-space-truly-empty

 

Ref.2   A NON-EXPANDING UNIVERSE- Available from Amazon books.