At https://phys.org/news/2019-07-einstein-relativity-theory.html … we seem to have two camps on Einstein and Relativity. The bigger group of scientists actively do research in order to sustain the theory (as that was what they were taught in their youth). The second, and smaller group seem to be constantly telling us Einstein's theory is about to tumble. In this latest study we are told Einstein's theory of Relativity is fraying at the edges. It is an interesting idea as the basis of their argument revolves around black holes – and the assumption mainstream is right about them. The article has the title 'Relativistic redshift of the star So-2 orbiting the galactic centre supermassive black hole' (see for example https://arxiv.org/pdf/1907.10731.pdf ). We are informed that a comprehensive test of general relativity near the monstrous black hole at the heart of the Milky Way appears to uphold Einstein's theory of Relativity – for now. We are then told we can absolutely rule out Newton's law of gravity. Observations are consistent with Einstein but his theory is vulnerable. It cannot explain gravity inside a black hole and at some point we will need to move beyond Einstein to a more comprehensive theory of gravity. The assumption the authors make is that the mainstream explanation of black holes is above board and uncontroversial. Is Einstein fraying at the edges or are black holes not what they are made out to be?
According to the authors the law of gravity should be valid everywhere in the universe. The star So-2 makes a complete rotation in three dimensions around the supermassive black hole – the full orbit taking 16 years. That is 16 years of observation is it not. They add, the black hole is four million times stronger than our sun as far as gravity is concerned – a denser kind of gravity that sucks in anything coming close (including stars). The research involved the study of photons (particles of light) as they travelled from So-2 to the Earth. Einstein's theory is said to to predict photons (or the dispersal of light) has to work harder near a black hole and it all depends on how fast the star might be orbiting (which is where the redshift comes in) and how much energy is required to escape the black hole's powerful gravitational field. Near a black hole gravity is theoretically much more dense and nothing can escape the gravitational pull – not even light. This is why they are invisible. We are then informed the influence on nearby stars is visible.