The Large and Small Magellanic Clouds, two of the Milky Way's better-known satellite galaxies.
Credit: Bessell and Sutherland, Mt Stromlo Observatory, Canberra.
BRISBANE: Newton's theory of gravitation may have to be modified to explain the behaviour of the Milky Way's satellite dwarf galaxies, claims a team of astronomers.
The number of companion dwarf galaxies, and the way they are distributed and moving cannot be explained by the laws of physics as they are currently understood, they argue in reports published in The Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society.
Foundations of cosmological theory
"Satellite galaxies hold important clues not only to the physical processes acting at early cosmological times, but also on the foundation of cosmological theory," said Helmut Jerjen, senior author of both papers and an astrophysicist at the Mt. Stromlo Observatory in Canberra, Australia.
Jerjen and his co-workers – at the University of Bonn in Germany and the University of Vienna in Austria – made the discovery by surveying the scientific literature on all the companion galaxies currently known.
Theory predicts that the satellite galaxies should be evenly distributed around the Milky Way, but, in fact, most of them lie in a kind of disc on the same plane, perpendicular to the spiral of the Milky Way, Jerjen said.
Furthermore, the galaxies are all moving in the same direction around the Milky Way, like planets around a star, which means they may have formed when a larger galaxy crashed into the Milky Way and disintegrated, Jerjen added.
Such a collision would have stripped the dark matter out of the shattered galaxy, before new dwarf galaxies condensed out the gaseous material left behind. The new galaxies would all continue to move in the same direction as the parent galaxy had been when it hit the Milky Way, but should contain very little dark matter.
Modifications to the theory
However, stars within the galaxies are moving faster than would be predicted from the amount of visible matter the galaxies contain, suggesting that they must also contain dark matter, which affects their gravity.
This finding could even hint that some of the fundamental principles of physics have been misunderstood, Jerjen said, and if that's that case, Newton's theory of gravitation might need to be modified for the fourth time in 100 years.
The theory has previously been modified by Einstein's special theory of relativity and later, general relativity, to explain discrepancies in gravity of objects at high velocities and in the presence of large masses. It was modified again with quantum mechanics to explain physics on sub-atomic scales.
The next step is to look for more satellite galaxies, Jerjen said, because the main source of information about nearby dwarf galaxies, the Sloan Digital Sky Survey, only covers the sky of the Northern Hemisphere.
Revise gravity
I think it is too early to conclude that the gravity law be revised at this time. We need more data from SDSS and SMSS and see what happen. As of now, it is inconclusive. Spherical dwarf galaxies do show strong evidence of dark matter.
Rewrite the law of gravity?
Newton made one forgivable error in his "law". He assumed, without proof, that gravity is an ATTRACTION. Merely replace that word by "LACK OF REPULSION" and we arrive at a system whereby the whole of Space is a source of electro-magnetic waves which produce a force of repulsion on all matter. Gravity results from one body being shielded from this repulsion by the presence of another!
Newton's Law follows from this arrangement so long as the two bodies are close enough to prevent much of the repulsive source intervening between them. But separate the bodies by a cosmic distance and his Law becomes: " F=Gm1m2/d(squared)-k.d " so that when "d", the distance, becomes large enough, "F" becomes negative and the expanding Universe has an explanation.
Such a source of repulsion is produced if we can assume that Space is populated by electrons, and they are energised by radiation from the many suns. They will generate electro-magnetic waves with a frequency so high that they penetrate all matter and act upon the nucleus of each atom that they encounter, so generating the repulsive force that we require.