The majority of cosmologists appear to have opted for dark matter as a way of explaining the odd behaviour of distant galaxies. However, there has been another option on the table for the last nearly 40 years. It has now been revived and given a dusting down. Stacey McGaugh and team [an international group of scientists] have come up with modified gravity – see https://phys.org/news/2020-12-unique-gravity-dark-theory.html … where the rival idea is said to explain why distant galaxies so not appear to conform with Newtonian gravity. There is, apparently, greater gravitational pull in space than current theory dictates. This led to the hypothesis of dark matter, an unseen substance making a contribution to the pull of gravity. Cosmologists, in recent years, have become wed to the idea of dark matter, a material that does not interact with light, an invisible and undetectable substance. This mikght be one way round the problem although the electric universe people have another theory.
Paul also sent in another story from The Times, back in November of 2020, which concerned Isaac Newton and his book, Philosophus Naturalis Principia Mathematica, which concerns the subject of gravity in space. At the time it was said to have baffled a lot of people, especially on the continent. The mathematics gave them a headache – or that has been the story for a long time. It seems they may have been somewhat obtuse as a new study has found a lot of first edition Principia books have survived which indicates the book was widely read and valued. Some 200 forgotten first edition copies of Principia have been found in libraries across the world, even in the Americas. The original manuscript is kept in the library of the Royal Society but a well kept copy recently sold in 2016 for the sum of 3.7 million dollars. The new study has actually come up with 386 copies in 27 countries – out of around 750 printed at the time. The findings are published in Annals of Science [2020].
The same copy of The Times also had a story on whales taking out Great White sharks. The whales in this instance are not whales as such but Orcas [known as killer whales]. This has been in the news on several occasions over the last few years. Apparently, Orcas in the ocean off South Africa have developed a taste for the liver of Great Whites. Subsequently, this had led to the disappearance of Great Whites in that part of the ocean. It coincides with the arrival in the region of a pair of Orcas that have been given names as they are sighted on a regular basis. Great Whites were commonly sighted at around 200 + a year as recently as 2016. Sightings have since dwindled to virtually nothing, escpecially in the last couple of years. Great Whites appear to be avoiding the seas off South Africa, and for good reason it would seem.