Planets and Dark Matter

6 Jul 2012

A paper published in Nature July 5th claims planets may form much faster than consensus theory currently allows - see http://phys.org/print260625944.html. This idea comes after they had witnessed a cloud of dust circling a young star disappear - just like that. Tommy Cooper would have been proud of the magic but the scientists were perturbed - and started thinking about what it might mean. It disappeared over a period of 3 years. This is very much a shorter period of time than expected. In fact, it is generally thought such gas and dust takes hundreds of thousands of years to disperse - and three years is just too short for the lifetime and demise of such a cloud. This stems from the belief that the dust is actually the raw material from which planets are made. So, what is wrong, the consensus - or do the planets form more quickly than expected.

At www.dailygalaxy.com/my_weblog/2012/07/dna-dark-matter-detector/ is about plans to build a dark matter detector using DNA (taken  from Technology Review and arXiv blog reports). Current experiments in the search for dark matter are looking for a signature. Dark matter is thought to leave behind tell-tale signs of its presence (see www.arxiv.org/abs/1206.6809). The same story pops up in the News at Cosmos - see www.cosmosmagazine.com/news/5765/scientists-shine-light-dark-matter/ where we are informed the 'cosmic web' of dark matter throughout the universe has finally been observed, confirming theories of how the universe was formed. This is out of the mouth of the lead author of a paper in Nature published on July 5th. Not only did we see a dark matter filament directly we also confirmed its total mass (dark matter and ordinary matter) and the amount of hot gas is in agreement with predictions. They used gravitational lensing to detect dark matter, where light from distant galaxies are deflected and bent by huge gravitational fields generated by other objects in space. The team devised a method to boost the lensing signal so that the dark matter filament between two clusters of galaxies could be observed through a ground based telescope. Gravitational lensing, he adds, is allowing us to see parts of the universe that were previously invisible. Research confirms that galaxy clusters form at the inter sections of vast filaments of dark matter.

In antoher story at the same web site, www.cosmosmagazine.com/features/online/5753/what-dark-matter - in the Features section (see menu on LH side of Home page)we have a title, 'What is dark matter?' It begins by saying it is one of the most perplexing puzzles in modern physics and was first mooted in the 1930s by Dutch astronomer Jan Oort and the Swiss astrophysicist Fritz Zwicky. Calculations seem to indicate there is a lot it out there - more abundant than ordinary matter. However, it does not emit, absorb or reflect light, the standard explanation of why it is invisible. Its existence is inferred from the gravitational forces it exerts on its surroundings. Hence, dark matter is a product of the consensus model - the assumption the universe is expanding. Stars and galaxies, in spite of this, don't move how they should move - they rotate faster than expected. This, and other oddities, are explained by the presence of large quantities of invisible mass. The extent to which light is bend and deflected around clusters of galaxies (gravitational lensing) provides further 'compelling' evidence for the presence of dark matter. However, not all scientists agree. Some physicists are dubious of the dark matter causing gravitational effectg and wonder aloud if science really understands how gravity actually works.